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ISSN #0071-0733 J O U 4 N A L
of the ‘fi
ENTOMOLOGICAL __
BRITISH COLUMBIA~
Vol. 86 Issued Sepember 30, 1989
ECONOMIC
E.N. Punnett & M.L. Winston ~ A comparison of honey bee (Apis mellifera L.)
colonies established from packages or nuclei in two areas of
PemU@oluna Dias, CANADA oo es 6s b.e os ab via Wes a0, cca 0 Gia eieiel suerelee wisie'e le wieie sie 1
D.F. Mayer, C.A. Johansen, C.H. Shanks, Jr. & A.L. Antonelli ~ Methomyl
insecticide and domesticated pollinators
GENERAL
R.A. Cannings ~ The robber flies (Diptera: Asilidae) of a Festuca grassland in
the Okanagan Valley, British Columbia
J.D. Wells & W.W. Cone ~ Biology of Erythroneura elegantula and E. ziczac
(Homoptera:Cicadellidae) on Vitis vinifera in Southcentral Washington
L.C. Stuart, B.A. Butt & R.L. Bell ~ Effect of host phenology on ovipositional
preference of winter form pear psylla (Homoptera:Psyllidae)
T.G. Gray & K.N. Slessor ~ Morphology, life history & identification of sex
pheromone components of an undescribed species of Choristoneura
(Lepidoptera:Tortricidae) on Scots pine in British Columbia
R.I. Alfaro ~ Probability of damage to Sitka spruce by the Sitka spruce weevil,
Pissodes strobi
S.M. Fitzpatrick ~ A potential collection method for Agapeta zoegana
(Lepidoptera:Cochylidae), a knapweed-root-feeding moth
L. Coop, A. Knight & G. Fisher ~ Parasitism of orange tortrix on caneberry,
Rubus spp. in western Oregon & Washington
TAXONOMIC
R.D. Kathman & D.R. Nelson ~ Pseudodiphascon arrowsmithi, a new species
of tardigrade from British Columbia, Canada (Macrobiotidae:Eutardigrada:
F. Kozar, L.M. Humble, R.G. Foottit and I.S. Otvos ~ New and little known
scale insects (Homoptera:Coccoidea) from British Columbia
S.G. Cannings ~ New records of slender winter stoneflies (Plecoptera:Capniidae)
in British Columbia
J.A. Santiago-Blay ~ Chalcidoids (Hymenoptera) reared from Artemisia tridentata
(Asteraceae) galls from British Columbia, Canada
A.R. Forbes & C.K. Chan ~ The aphids (Homoptera: Aphididae) of British
Columbia 19. Further additions
R.A. Cannings & C.S. Guppy ~ Glover’s Silkmoth Hyalophora gloveri (Strecker)
(Lepidoptera:Saturniidae), new to British Columbia
R.A. Cannings ~ An Asian hornet, Vespa simillima xanthoptera (Hymenoptera:
Vespidae) in North America
ERRATUM
ISSN #0071-0733 J O U it N AL
of the
ENTOMOLOGICAL
SOCIETY of
BRITISH COLUMBIA
Vol. 86 Issued Sepember 30, 1989
ECONOMIC
E.N. Punnett & M.L. Winston ~ A comparison of honey bee (Apis mellifera L.)
colonies established from packages or nuclei in two areas of
Iritishy Colma C ange) gec.c ow crowns Sea Se eo Oe whe Nes ORE eee eee Sees 1
D.F. Mayer, C.A. Johansen, C.H. Shanks, Jr. & A.L. Antonelli ~ Methomyl
insecticide and domesticated pollinators ............cc cee ce cece cs ececees 7
GENERAL
R.A. Cannings ~ The robber flies (Diptera: Asilidae) of a Festuca grassland in
the Okanagan Valley, British Columbia ............ cece ececcccccsccceecs 14
J.D. Wells & W.W. Cone ~ Biology of Erythroneura elegantula and E. ziczac
(Homoptera:Cicadellidae) on Vitis vinifera in Southcentral Washington ........ 26
L.C. Stuart, B.A. Butt & R.L. Bell ~ Effect of host phenology on ovipositional
preference of winter form pear psylla (Homoptera:Psyllidae) ................ 34
T.G. Gray & K.N. Slessor ~ Morphology, life history & identification of sex
pheromone components of an undescribed species of Choristoneura
(Lepidoptera:Tortricidae) on Scots pine in British Columbia ................ 39
R.I. Alfaro ~ Probability of damage to Sitka spruce by the Sitka spruce weevil,
PASS OMESUSEVOON SEE Aie tS gp USE ae aed tee lots BS Salas OE ARES 48
S.M. Fitzpatrick ~ A potential collection method for Agapeta zoegana
(Lepidoptera:Cochylidae), a knapweed-root-feeding moth ...............005. 25
L. Coop, A. Knight & G. Fisher ~ Parasitism of orange tortrix on caneberry,
Rubus spp. in western Oregon & Washington ............cececeececeececs 63
TAXONOMIC
R.D. Kathman & D.R. Nelson ~ Pseudodiphascon arrowsmithi, a new species
of tardigrade from British Columbia, Canada (Macrobiotidae:Eutardigrada:
ari gr ada) tices ne CO tre Ie ete eweie aves Rate ene ohne Oe: 66
F,. Kozar, L.M. Humble, R.G. Foottit and I.S. Otvos ~ New and little known
scale insects (Homoptera:Coccoidea) from British Columbia ................ 70
S.G. Cannings ~ New records of slender winter stoneflies (Plecoptera:Capniidae)
HAP HIESNEC OLUMOIAY = ara eesveeiiniaes Sueaine oe cio natemecu ania ta aad oe ee eeRiCk 77
J.A. Santiago-Blay ~ Chalcidoids (Hymenoptera) reared from Artemisia tridentata
(Asteraceae) galls from British Columbia, Canada ...............0cceeeeeee 80
A.R. Forbes & C.K. Chan ~ The aphids (Homoptera: Aphididae) of British
Columbia 19. Further additions ¥ ¢4:a/26-4 1s awe swash see esle dw evens « eee ed be Mee 82
R.A. Cannings & C.S. Guppy ~ Glover’s Silkmoth Hyalophora gloveri (Strecker)
(Lepidoptera:Saturniidae), new to British Columbia .................0.0000- 89
R.A. Cannings ~ An Asian hornet, Vespa simillima xanthoptera (Hymenoptera:
NESpiGac) I. NOKMeA MeLICe, ...c.) sain seyi sae wstols niu a ayes cha dese aetna eee as 91
ERRATUM ree nas teen oc Pee eee ea Pane eee ne Lae 33
DIRECTORS OF THE ENTOMOLOGICAL SOCIETY
OF BRITISH COLUMBIA FOR 1988-1989
President
Chris Guppy
Royal B.C. Museum, Victoria
President-Elect
David Raworth
Agriculture Canada, Vancouver
Past President
Murray Isman
University of British Columbia, Vancouver
Secretary-Treasurer
Kathy Millar
R.R. 3, McLay Rd., Duncan, B.C. V9L 2X1
Editorial Committee (Journal)
H.R. MacCarthy R. Ring D. Raworth
Editor (Boreus)
R. Cannings
Directors
K. Millar (2nd) R. Vernon (2nd)
G. Salloum (Ist) B. Petersen (1st) R. Smith (1st) |
Hon. Auditor
Chris Guppy
Regional Director of National Society
Imre Otvos
Pacific Forestry Centre, Victoria
J. Enromo. Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 1
A COMPARISON OF HONEY BEE (Apis mellifera L.) COLONIES
ESTABLISHED FROM PACKAGES OR NUCLEI IN TWO AREAS OF BRITISH
COLUMBIA, CANADA
ELIZABETH NEILSON PUNNETT
Mark L. WINSTON
DEPARTMENT OF BIOLOGICAL SCIENCES
SIMON FRASER UNIVERSITY
BURNABY, B.C. CANADA V5A 186
SUMMARY
A comparison of the biological performance and economic returns from honey bee
colonies established in April from either 0.9 kg packages or four-frame nuclei was made
in both the Lower Fraser Valley and Peace River areas of British Columbia. In the
Lower Fraser Valley, nuclei were superior to packages both biologically and economi-
cally, while in the Peace River, no biological differences were found between the two,
and packages provided higher economic returns. Either packages or nuclei would be
viable in commercial beekeeping operations, depending on individual circumstances.
INTRODUCTION
A new honey bee (Apis mellifera L.) colony may be established in the spring from either a
package or a nucleus. A package consists of 0.9-1.8 kg of bees (7,500-17,000 bees) plus a
queen. The bees are transported in a wooden box covered on each side with wire screen to
provide ventilation, with a metal can containing sugar syrup hung inside the box to feed the
bees during transit. A nucleus consists of three to five frames of bees, brood, honey and pollen
plus a queen, and is commonly transported in a cardboard box with a screened lid to allow for
ventilation. Before the First World War, nuclei were widely used in the U.S. and Canada for
establishing colonies. Fear of disease transmission reduced the demand, however, and the
package bee business developed, so that packages purchased from shippers in the southern
states replaced the nuclei used earlier (Johansson and Johansson 1970). Recently, a renewed
interest in nuclei has been shown by beekeepers (Winston 1983). However, research on the
comparative biological performance and economic returns to the purchaser from use of
packages and nuclei is needed if nuclei are to be accepted commercially.
Nuclei are more expensive to purchase than packages; $35.00 for a four-frame nucleus
versus $29.70 for a 0.9 kg package (McCutcheon 1984). In addition, nuclei must be inspected
to ensure they are disease free, and standards for nuclei are not as precise as for packages. The
bee population and brood, honey or pollen areas may vary greatly among producers of nuclei.
However, nuclei have one principal advantage over packages. A nucleus contains drawn
comb, stored honey and pollen, and, most importantly, brood, all of which should enhance
early population growth. This may be a critical factor in regions with short growing seasons, as
in most of Canada.
The objective of this research was to compare the biological performance and economic
returns from 0.9 kg packages and four-frame nuclei established in April in both the Lower
Fraser Valley and Peace River areas of B.C.
MATERIALS AND METHODS
A. Lower Fraser Valley
This study was conducted from April to August 1984 at a single apiary site in Langley, in the
Lower Fraser Valley area of southwestern British Columbia. A total of 20 colonies were
established on 17 April, each in a single super (drawn comb) of standard Langstroth equipment
(497 mm x 420 mm x 241 mm deep). Ten colonies were established from 0.9 kg packages and
10 colonies from four-frame nuclei. All colonies were headed by Italian (Apis mellifera
ligustica L.) queens imported from Florida.
Colonies were managed throughout the season for honey production using standard
techniques. A second brood super and either one or two honey supers were added as required
(standard Langstroth equipment). Sixteen and a half liters of sugar syrup were fed to all
2 J. ENTOMOL Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
colonies between 17 April and 26 May to facilitate colony growth. Oxytetracycline hydro-
chloride mixed in icing sugar also was fed to all colonies from 22 April to 12 July for brood
disease prevention.
Five colony characteristics (sealed brood, honey and pollen areas, colony weight, and
frames of bees) were measured approximately every 21 days from 10 May to 1 August. Sealed
brood, honey and pollen areas were measured using a plexiglass grid to estimate the area on
each frame. All colonies were weighed with a tripod scale. Colony weight was determined by
subtracting the weight of empty equipment from the tripod scale reading. The number of
frames of adult workers was estimated by looking through the super from above and below to
determine how many frames were covered by workers. Extracted honey was determined in
August by weighing supers before and after frames of honey were extracted. All colonies were
left with six full frames of honey after the honey removal in August. For economic analyses,
honey was valued at $1.12 per kg, the average sale price of bulk honey in B.C. in 1984
(McCutcheon 1984). The purchase prices of 0.9 kg packages and four-frame nuclei were
valued at $29.70 and $35.00 respectively (McCutcheon 1984).
Student’s t-test was used to test for significant differences between experimental treatments
(P<0.05).
B. Peace River
On 17 April, 1984 ten 0.9 kg packages and ten four-frame nuclei were transported by truck
to a 1500-colony commercial beekeeping operation in the Peace River region of British
Columbia, and maintained throughout the season by the cooperating beekeeper, Dale Hansen.
The packages and nuclei were established in a single super (drawn comb) of standard
Langstroth equipment and managed throughout the season for honey production using
standard techniques. All colonies were headed by Italian queens imported from Florida.
Colonies were weighed twice during the season; 5 June and 3 July. Extracted honey was
determined in August by weighing supers before and after frames of honey were extracted.
The same figures listed in part A were used for economic analyses.
Student’s t-test was used to test for significant differences between experimental treatments
(P<0.05).
RESULTS
A. Lower Fraser Valley
By 1 August the biological characteristics did not differ significantly between packages and
nuclei (P>0.05) except for colony weight, where the nuclei weighed significantly more than
the packages (P=0.02) (Fig. 1). Significant differences in biological characteristics occurred
on various earlier measurement dates, with nuclei always recording higher measurements than
packages. The nuclei produced significantly more honey than did the packages (P=0.03) (Fig.
1). Both nuclei and packages recorded deficits of $12.94 (Canadian) and $18.28 (Canadian)
respectively (Table I).
B. Peace River
Colony weight on both measurement dates and extracted honey did not differ significantly
between packages and nuclei (P>0.05) (Fig. 2 and 3). Packages provided higher incomes than
nuclei, $57.77 (Canadian) and $52.36 (Canadian) respectively (Table I).
DISCUSSION
The results of this study suggest that both packages and nuclei are commercially viable in
B.C., and which is used will depend on area and compatability with an individual’s beekeeping
operation. By 1 August the packages and nuclei in the Lower Fraser Valley differed
significantly only in colony weight and extracted honey (Fig. 1). The packages produced
significantly less extracted honey than the nuclei, possibly due to a smaller fotaging force
during the nectar flow. In the Langley area the major nectar flow is in July (McCutcheon
1982); on 20 June (approximately one week before the beginning of the nectar flow) and 12
July (during the nectar flow) the packages had a significantly smaller worker population than
J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
Oy ‘ASNOH G3LOVYLX3S
Oy “LHOISM
AQ WW Qk \™Wrrs
Mmm PACKAGES
NUCLEI
KZ
0001 XWO'OS ‘GOOus G31V3s
I. WX
000 I XWO'OS ‘ASNOH
[e) (eo) (e)
WN =
$338 40 SAWVYS
0001 XWO'OS ‘N3110d
P<0.005).
PS0i01, ***
PSOI05, = *
0.9 kg packages and four-frame nuclei in the Lower Fraser Valley. Standard errors are represented by
bars above each histogram. (*
Figure 1: Biological (sealed brood, honey and pollen areas, frames of bees and colony weight) and
economic (extracted honey) characteristics on five measurement dates for colonies established from
J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
TABLE I
Incomes from colonies established from 0.9 kg packages and four-frame
Treatment
Package
Nucleus
40
30
©
Ne
=
6 20
LL
=
10
nuclei in the Fraser Valley.
Purchase Extracted Honey Total
Price Honey Income Income
($) (kg) ($) ($)
29.70 10.2 11.42 -18.28
35.00 19.7 22.06 -12.94
Figure 2: Colony weight on two measurement dates for colonies established from 0.9 kg packages and
four-frame nuclei in the Peace River. (P>0.05 on both dates).
the nuclei, but both treatments were maintaining equivalent brood areas (Fig. 1). This meant
that the packages had a greater proportion of their worker population involved in brood
caring, resulting in a smaller foraging force. Previous research has reported the tendency of
small colonies to allocate a high proportion of available resources to brood rearing, resulting in
low honey production (Farrar 1968). The worker population in colonies started from packages
peaked after the nectar flow (1 August) (Fig. 1), resulting in a significantly lower honey yield
than the nuclei.
J. Enromot Soc. Brrr. COLUMBIA 86 (1989), SEPT. 30, 1989 5
80
60
40
20
EXTRACTED HONEY, KG
PACKAGE NUCLEI
Figure 3: Extracted honey for colonies established from 0.9 kg packages and four-frame nuclei in the Peace
River. (P>0.05).
TABLE II
Incomes from colonies established from 0.9 kg packages and four-frame
nuclei in the Peace River.
Purchase Extracted Honey Total
Treatment Price Honey Income Income
($) (kg) ($) ($)
Package 29.70 78.1 87.47 a1)
Nucleus 35.00 78.0 87.36 52.36
The packages and nuclei in the Peace River were not monitored as closely as those in the
Lower Fraser Valley. The colonies in the Peace River had only colony weight measured on two
dates, and extracted honey determined at the end of the season. Packages and nuclei in the
Peace River produced equivalent amounts of extracted honey (Fig. 3), whereas in the Lower
Fraser Valley, nuclei produced significantly more extracted honey than packages (Fig. 1). This
difference was probably due to the later honey flow in the Peace River, which begins in mid-
July, two weeks later than in the Lower Fraser Valley. This allows packages to “catch up”’ to
nuclei before the honey flow, thereby producing equivalent amounts of extracted honey. In the
6 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
Lower Fraser Valley, the honey flow began before the packages were as populous as the nuclei,
and they did not produce as much extracted honey. The suitability of packages and nuclei for
honey production would appear to be at least partially dependent on the timing of the
honeyflow in an area. Had 1983 been a severe spring rather than mild in the Peace River, the
nuclei may have performed better than the packages due to their initial advantage of brood and
a slightly larger worker population (D. Hansen, personal communication).
Economically, the results from the Lower Fraser Valley and the Peace River also differed. In
the Lower Fraser Valley, neither nuclei or packages provided an income (Table I), whereas
both packages and nuclei provided incomes in the Peace River (Table IT). In the Lower Fraser
Valley in 1984, a relatively poor year, nuclei and packages produced deficits of $12.94 and
$18.28 respectively. In seasons with both a good nectar flow and good weather, both nuclei and
packages may provide an income in the Lower Fraser Valley. Under such conditions nuclei
would likely provide the greater income, since they have a larger foraging force available
during the early honeyflow characteristic of the Lower Fraser Valley. In the Peace River, both
packages and nuclei yielded incomes, but packages provided a higher income ($57.77) than
nuclei ($52.36) due to their lower purchase price (Table ID.
The beekeeping operation in the Peace River to which the packages and nuclei were sent has
traditionally been based on spring package management. The cooperating beekeeper found the
nuclei more labor-intensive from the standpoint of transportation and installation (D. Hansen,
personal communication), partly because his operation was set up to accommodate packages,
not nuclei. In the Lower Fraser Valley study no difference was noted in ease of transportation
of packages and nuclei, and the nuclei were considered to be easier to install than the packages.
Numerous researchers have made biological and economic comparisons between packages
of different sizes established on different dates (reviewed in Nelson and Jay 1972). However,
comparisons between packages and nuclei have been lacking. To our knowledge, this
experiment represents the only comparison made between packages and nuclei. If Canadian
beekeepers are to become self-sufficient, both packages and nuclei will have to be incorpo-
rated into beekeeping operations. This preliminary research indicates that either packages or
nuclei would be viable in commercial beekeeping operations, depending on individual
circumstances. In the Lower Fraser Valley nuclei are superior to packages both biologically
and economically, while in the Peace River, no biological differences were found between the
two, and packages provided greater economic returns than nuclei. However, research for more
than one season and in various beekeeping areas of the province is needed to establish the
suitability of packages versus nuclei for honey production.
ACKNOWLEDGEMENTS
We are grateful to Linda Fergusson and Stephen Mitchell for field assistance; and to Dale
Hansen for his cooperation and assistance in this project. Financial support was provided by
British Columbia Science Council and Natural Sciences and Engineering Research Council
grants (M.L. Winston, principal investigator) and a Natural Sciences and Engineering
Research Council Postgraduate Scholarship (to E.N. Punnett).
REFERENCES
Farrar, C.L. (1968) Productive management of honey-bee colonies. Am. Bee J. 108: Nos. 3-10
Hansen, D. (1985) Personal communication
Johansson, T.S.K. and M.P. Johansson (1970) Establishing and using nuclei. Bee World 51:23-25
McCutcheon, D.M. (1982) Charting nectar flows and their use in bee management. British Columbia Ministry of
Agriculture and Food, Bee Notes
McCutcheon, D.M. (1984) Annual report 1984 apiculture program. British Columbia Ministry of Agriculture and
Food. Clearbrook, B.C.
Nelson, D.L. and S.C. Jay (1972) Population growth and honey yield studies of package bee colonies in Manitoba.
11. Colonies initiated with four package sizes on one date. Manitoba Entomologist 6:17-22
Winston, M.L. (1983) Research Review. British Columbia Honey Producers Association Newsletter, 4th Quarter,
p.7
J. ENToMo_ Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 7
METHOMYL INSECTICIDE AND DOMESTICATED POLLINATORS!
D.F. Mayer, C.A. JOHANSEN2, C.H. SHANKS, JR.3, AND A.L. ANTONELLI*
DEPARTMENT OF ENTOMOLOGY
WASHINGTON STATE UNIVERSITY
IRRIGATED AGRICULTURE RESEARCH & EXTENSION CENTER
PROSSER, WASHINGTON 99350
ABSTRACT
Susceptibility to methomy]l sprays was greatest for the alfalfa leafcutting bee, Mega-
chile rotundata (F.); least for the honey bee, Apis mellifera L.; and intermediate for the
alkali bee, Nomia melanderi Cockerell. Methomy! at 1.12 kg (Al)/ha had low residual
hazard to honey bees, and at 0.6 kg (AI)/ha it had low residual hazard to leafcutting and
aklaki bees after one day. Field tests of methomy] on pollen-shedding corn, blooming
red raspberry, and blooming blueberry resulted in reduced bee visitation and low adult
bee mortality.
Insecta, Bees, Pollinators, methomyl
INTRODUCTION
Methomyl is a carbamate insecticide available in wettable powder, dust, and liquid
formulations. It kills as a contact or stomach poison and is registered for insect control on a
large number of agricultural crops.
Bee poisoning or the killing of beneficial bees from pesticides is a serious problem for
beekeepers in most parts of the world (Johansen and Mayer, 1989). For 35 years we have
evaluated pesticides for their effects on bees and developed information to reduce bee
poisoning (Mayer and Johansen, 1988).
This paper reports the results of research concerning the effects of methomy] on the honey
bee, Apis mellifera L., alkali bee, Nomia melanderia Cockerell, and alfalfa leafcutting bee,
Megachile rotundata (F.). Also reported are the insecticide’s effects on honey bees when
applied to pollen-shedding corn, blooming red raspberry, and blooming blueberry.
MATERIALS AND METHODS
Small-scale Bioassays. Tests were conducted with different formulations and rates of
methomyl on honey bees, alkali bees, and alfalfa leafcutting bees, from 1968 through 1987.
Methomy] was applied to 0.004-ha plots of alfalfa with a Solo® backpack boom sprayer, using
1758 g/cm? pressure and 234 liters of water/ha. Treatments of field-weathered methomy]
residues were replicated four times with four foliage samples per treatment and time interval.
Samples consisting of about 500 cm? of foliage taken from the upper 15-cm portions of plants
were placed in each plastic petri dish (15 cm diameter) whose tops and bottoms were separated
by a wire screen (6.7 meshes/ cm) insert (45 cm long and 5 cm wide). The same procedure was
used in the following tests: residual toxicity of methomyl combined with the stickers Adhere®
and Plyac (both United Agr. Products, P. O. Box 1286, Greeley, CO 80632).
The residual toxicity of methomyl combined with the formamidine insecticide chlor-
dimeform also was tested. Residual toxicity of repeated applications (4 times) of methomyl
also was evaluated as was the effect of methomy] on alfalfa leafcutting bees of different ages.
In one test, treated foliage was held in the lab in the dark at 18 or 29°C, or outdoors in 18-35°C
variable day-night temperatures and daily sunlight. In still another test, 50 honey bees were
placed in each of 4 cages as described above and methomy] was applied directly onto the bees.
FOOTNOTES
1 Washington State University, College of Agriculture and Home Economics Research Center.
Work done under Projects 0742 and 1957.
2 1135 Oak Court, Coeur d’Alene, ID 83814.
3 Wash. State Univ., Southwestern Wash. Research Unit, 1919 N.E. 78th St., Vancouver, WA
98665.
4 Wash. State Univ., Western Wash. Research and Extension Center, Puyallup, WA 98371.
8 J. ENromot Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
Worker honey bees were obtained from colonies and anesthetized with CO,. Prepupae of
leafcutting bees and alkali bees, in leaf piece cells and soil cores, respectively, were incubated
at 29-31°C and 60% RH. Emergent adults were trapped in canisters fitted with screen funnels
and chilled to facilitate handling. Residue test exposures were replicated four times by caging
60 - 75 worker honey bees, 25 - 40 leafcutting bees, or 15 - 20 alkali bees with each of four
foliage samples per treatment and time interval. Bees were maintained in cages at 29°C, 60%,
RH and fed 50% sucrose solution (1:1) in a cotton wad (5 by 5 cm). Bee mortality was
determined after 24 h. Abbott’s formula (Abbott 1925) was used to correct for mortality
occurring in the untreated check. Data were analyzed using analysis of variance (ANOVA)
techniques with mean separation by Duncan’s Multiple Range Test (Duncan, 1951).
Field Tests -- Corn. In 1973 methomy] was tested for bee toxicity on pollen-shedding
‘Jubilee’ sweet corn in a 4.5-ha field and in 1983 in a 55-ha field near Prosser, WA. In 1973,
methomy] 90% soluble powder (SP) was applied by airplane before 0700 h on 3 Sept, using
0.5 kg (AD/ha in 45 liters of water. A 9-ha field 1 km away served as the untreated check. In
1983, methomyl 90% wettable powder (WP) was applied by helicopter before 0700 h on
2, 6, 10 and 14 Sept, using 0.5 kg (AI)/ha in 20 liters of water. A 55-ha field 1 km away served
as the untreated check.
Honey bee colonies with Todd dead bee traps (2 in 1973; 6 in 1983) were located adjacent to
the fields 3 days before the first application. In 1973 and 1983, the number of dead honey bees
was recorded daily before and after the applications. In 1983, 25 dead bees from each colony
were examined during each sample for tongues fully extended, and the data were recorded.
Also in 1983, data on the number of corn pollen collectors per 25 foragers per colony for a total
of 150 bees per sample were recorded. Colony conditions were evaluated before and after each
application and at the conclusion of each test.
Field Tests -- Raspberries. In 1983, methomy] was tested for bee toxicity on blooming red
raspberry near Vancouver, WA. Methomyl] 90 SP was applied at 0.5 kg (AI)/ha and at 1.0 kg
(AD/ha to separate 0.02-ha plots of ‘Meeker’ red raspberry, and a separate 0.02-ha plot was left
untreated. Applications were made on 26 July at 2000 h by ground equipment with a hooded-
boom sprayer. Two weeks before the application, four honey bee colonies were placed near the
center of the field. Bee numbers and foraging behavior were assessed in the plots during mid-
afternoon of the first day after application and on days 2, 3, and 6 following application. The
number of honey bees foraging on 14 meters (5 replications) of row were counted in each plot
on each date.
On 27 July, at 0600 h, 200 blooms in each plot were covered with white paper bags, to
exclude bees so that nectar samples could be taken. Three kinds of samples were taken from
each plot: (1) 200 flowers that were rinsed in 200 ml of distilled water, (2) the’ rinse water
drained from the flowers, and (3) 20 1 of floral nectar collected from each of 20 flowers.
Samples were taken at 0800 h and 1200 h, frozen, and sent to E. I. DuPont de Nemours and
Company chemists for analysis of methomy] residues. We consistently obtained 15-20 |1liters
of nectar per flower (av. 17) with 50% sugar content. Data were analyzed using ANOVA
techniques with mean separation by Duncan’s Multiple Range Test (Duncan, 1951).
Field Tests -- Blueberry. Methomy] 1.8 soluble liquid (LS) (1.0 kg (AT/ha) was applied in
936 liters of mixed spray per ha at 1000 h on 16 April 1987. Biofilm wetting agent at the rate of
473 ml per 379 liters was added. The plots consisted of 9 x 8 m of ‘Berkeley’ blueberry in full
bloom adjacent to six honey bee colonies. The weather was cool and overcast at 13°C with a
light northwest wind at 11-13 kph. A few bumble bees were working in the blueberries, but no
honey bees. Twenty white paper bags were placed on blooming tips in the treated plots and on
tips in the check plots (33 m west and 33 m east) at 1230 h. The temperature increased to 14°C
by 1600 h, but light rains started at 1630 h.
April 17 was cool and rainy and no honey bees were working. Nectar samples were
extracted from the bagged blooms using a micropipet. There was an average of 10.2 liters of
nectar per flower with an average 24% sugar content. On 18 April the weather was still cloudy
with occasional light rains, but was suitable at times to observe honey bee activity. The number
of honey bees foraging on 15 meters of row was determined for each plot.
J. ENromMot Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 9
RESULTS
Small-scale Bioassays. Table 1 presents the means of bioassay tests done from 1968
through 1973. The mortality sequence for the three species was typical in that alfalfa
leafcutting bees were most susceptible, alkali bees were intermediate in susceptibility, and
honey bees least susceptible to methomyl. Bee susceptibility to an insecticide is a function of
size or surface/volume ratio which is related to chance adherence of residues to the body of a
forager (Johansen et al., 1983). The mortality of bees in 24 h continuous contact with treated
foliage samples decreased as the age of residues increased. The 2% dust formulation was more
hazardous than other formulations, causing 46 - 98% mortality one day after application. For
the other formulations, the rates of 0.6 kg(AI/ha or lower caused less than 25% mortality of
honey bees 3 h after application. The rate of 1.12 kg(AI)/ha caused 27% or lower mortality
after 8 h. Methomyl 1.8 LS (0.3 kg/ha) and methomyl 90 WP (0.6 and 1.12 kg/ha) applied
directly to honey bees caused 100% mortality.
Adding the sticker Adhere® significantly reduced mortality for all three bee species.
Adding Plyac® did not always reduce bee mortality. Mayer et al. (1987) showed that adding
the sticker Bond® to methomy] and Johansen (1972) showed that adding Evanol to methomyl
resulted in reduced bee mortality.
Repeated applications of methomyl] at 5-day intervals caused increasing mortality with
successive treatments (Table 3). For example, with honey bees, mortality for each application
was 19, 28, 41, and 63%.
Adding chlordimeform 97% soluble powder (SP), a material essentially non-hazardous to
bees (Mayer & Johansen, 1988), at 0.3 kg/ha to methomy] 1.8 LS at 0.3 kg/ha, resulted in a
synergistic effect that increased honey bee mortality from 2 h residues by 72%.
Methomy] 1.8 LS (0.3 kg/ha) caused 51% mortality in 4-wk-old leafcutting bees but only
8% in 1-2-day-old bees. In general, older leafcutting bees that have been nesting for 3 or more
weeks have increased susceptibility to poisoning by most insecticides (Mayer & Johansen,
1988).
Table 1.
Mortality of alkali bees (AB), alfalfa leafcutting bees (LB), and honey bees (HB), exposed to
different age residues of methomyl applied to field plots of alfalfa. Pullman, WA, 1968-1973.
Rate 24-h mortality (%) of bees caged with
Methomy! (kg(AI) treated foliage at indicated
Treatment? /ha) age of residues
AB LB HB
3h 8h 24h 72h 3h 8h 24h 72h 3h 8h 24h
18LS 03 3 0 - - 13 5 0 - 2 O 0
18LS 06 24 £0 - - 23 6 Z - 235 0 0
18LS 1.12 61 38 19 - 86 59 65 . 43 10 3
25 WP 0.6 - - - - - - - - 20. Yo l
90 WP 0.6 47 8 - - 48 13 4 - 18 § ps)
90 WP 1.12 96 64 #40 16 83 73 #860 = 13 92 27 1
90SP 03 Oe 2 - - 11 3 a - 4 3 0
90SP 05 - - - - - - - - 26 #O 0
90SP 0.6 - - - - - - - - 1S as 0
90 SP 12h ne - - - - - - - 44 21 0
2% dust 0.6 - - - - 100 100 100 - 100 75 46
2% dust 1.12 100 90 84 - 100 100 88 - 100 98 98
aLS, liquid; WP, wettable powder; SP, soluble powder
10 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
Table 2.
Mortality of alkali bees (AB), alfalfa leafcutting bees (LB), and honey bees (HB), exposed to
different age residues of methomy] applied to field plots of alfalfa. Prosser, WA, 1987.
24-h mortality (%) of bees caged with
Rate treated foliage at indicated
Treatment (kg (Al)/ha) time after treatment
AB LB HB
2h 68h 2h SHO HB
Methomyl 90 WP_ 1.0 83a 78a 86a 50a 69a - 36a
Methomy! 90 WP + 1.0 + 118 ml 34b «©26b )«=660b-)S 31b~—Ss:18b - 13b
Adhere
Methomy! 90 WP + 1.0 + 118 ml 43b 39b 60b 63a = 21b - 3la
Plyac
Means within a column and year followed by the same letter are not significantly different (P =
0.05; Duncan’s [1951] multiple range test).
Table 3.
Mortality of alkali bees (AB), alfalfa leafcutting bees (LB), and honey bees (HB),
exposed to residues of methomyl 1.8 LS (0.5 kg (AID/ha) from successive
applications to plots of alfalfa. Pullman, WA, 1976.
24-h mortality (%) of bees caged
with treated foliage at indicated
Treatment?/ time after treatment
AB LB HB
2h 2h 2h 8h
Ist application 9a 36a 19a 4a
2nd application 22 b 52 b 28 a 11 b
3rd application 42¢ 54 b 41 b 16 b
4th application 89 d 55 b 62 Cc 62 c
Means within a column and followed by the same letter are not significantly
different (P = 0.05; Duncan’s [1951] multiple range test).
a/ Application dates: 12, 17, 22, 27 June.
The effects of temperature and sunlight on methomy] activity against honey bees are shown
in Table 4. Two- and 8-h residues held at 18°C and 29°C in constant dark caused significantly
less mortality than the residues held in variable day-night temperatures and exposed to
sunlight. This is the reverse of expected results (Johansen et al., 1983). Perhaps sunlight and
heat caused the methomy! to break down to a more toxic product.
Field Tests -- Corn. In 1973, the Todd trap catches for the first 24 h after application
averaged 13 bees next to the treated field and 20 in check colonies 1 km distant. Methomy]
applied to pollen-shedding corn in 1983 resulted in no abnormal loss or perhaps a low kill
(Table 5). Use of Todd dead bee traps on honey bee colonies has shown that up to 100 dead
bees per day is anormal die-off, 200-400 is a low kill, 500-900 is a moderate kill, and 1000 or
more is a high kill (Mayer & Johansen, 1983). Bees dying with tongues extended is often a sign
J. ENToMoL Soc. Brir. COLUMBIA 86 (1989), SEpr. 30, 1989 11
Table 4.
Mortality of honey bees exposed to different age residues of methomyl 90 SP
applied to field plots of alfalfa at the rate of 1.0 kg (AD/ha. Residues were held
under different environmental conditions before bee exposure.
Prosser, WA, 1987.
24-h mortality (%) of bees caged
with treated foliage collected at
Treatment indicated times after treatment
2h 8h 24 h
18°C - constant dark 28a 9a Oa
29°C - constant dark 49a 6a la
18-35°C - outdoors, 77b 36b la
daily sunlight
Means within a column and followed by the same letter are not significantly
different (P = 0.05; Duncan’s [1951] multiple range test).
Table 5.
Effect of methomy]l applied to sweet corn at 0.5 kg (AI)/ha on honey bee foragers
returning to the hive with corn pollen and on honey bee mortality, based on Todd
dead bee traps, in colonies placed adjacent to treated sweet corn fields.
Prosser, WA, 1983.
Mean No. dead bees/colony/day % bees bringing in
Date (% with tongues fully extended) com pollen**
Aug. 29 25 (41) 73
30 12 (44) 74
31 28 (42) 71
Sept. l 10 (43) 65
Ze 74 ~=(65) 22
3 170 (61) BY
4 137 (64) 50
5 100 (62) 79
6* 104 (54) 36
7 66 (55) 51
8 260 (52) --
9 77 (44) 55
10* 38 (42) 40
11 250 = (50) 41
1 109 (57) 32
13 53 (38) 51
14* 83 (36) 45
15 214 (42) 31
16 27 25
Ig) 42 2
* Applied by aircraft at 0600 h on these dates.
**Sample size-150 bees on each date.
of bee poisoning, especially with organophosphates (Johansen, 1984), but with methomyl
there was no difference in the number of dead bees with tongues extended. Bees collecting
com pollen were reduced by about 30% for one day after application. There were no
reductions in bee populations or brood in the colonies at the end of the test.
Field Tests -- Raspberry. As soon as bees began foraging raspberry blooms the day after
application their behavior changed. They removed nectar, backed away, and soon were
avoiding treated blooms. Sometimes they would move onto a leaf to groom themselves.
12 J. ENTOMOL Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
Table 6.
Effect of methomyl applied on 26 July at 2000 h on honey bees foraging in
blooming red raspberries. Vancouver, WA, 1983.
Mean Number foraging bees/14 m of row
Kg (AlD)/ha 27 July 28 July 29 July 1 August
0.5 Q * 6 * 21 * 64 ns
1.0 4 * 1 * 15 * 78 ns
Untreated check 56 61 69 68 ns
*Values are Significantly different (P = 0.05) from untreated check value in
respective column. Pooled t test.
Within a short time, most bees drifted along the rows to the check block. Methomyl was
strongly repellent to the bees for 2 days but less so on the third day. Bees resumed normal
activity by the 6th day (Table 6).
Most methomyl residues detected from flower surfaces (water wash), flower interiors
(homogenized flowers), and nectar showed some degradation between the 0800 h and 1200 h
samplings. However, only surface residues were reduced greatly during the 4-h period. The
minimal amounts of residue detect-ed in the untreated check plot samples were a true
reflection of the spray application. The hooded boom sprayer was driven through all three
adjacent plot rows during each pass because of space limitations. No doubt there was a
minimal contamination of the check plot during this process (Table 7).
Table 7.
Residues of methomyl detected in red raspberry flower and nectar samples 27
July. Vancouver, WA, 1983.
Methomy] residues (ppm)
0800 h 1200 h
Flower Homogenized Flower Homogenized
Kg (AD/ha surface flowers Nectar surface flowers Nectar
0.5 2.0 a 8.la 3.4 a 0.27 a 2.la 2.8 a
1.0 2.6 a 9.0 a 6.9 b 0.91 b 9.3 b 5.3 b
Untreated check 0.05b 0.29b <0.02c 0.04 c 0.28c <0.02c
Means within a column and followed by the same letter are-not significantly different
(P = 0.05; Duncan’s [1951] multiple range test).
Field Tests -- Blueberry. Honey bees started to enter the blueberry field by 0930 h, but
there were too few to make useful counts in the plots. After 2 days of inactivity, bees started
foraging in fair numbers by 1100 h, even though the temperature was only 12°C. The same
kind of response, which was first observed with methomy] in red raspberry investigations in
Table 8.
Effect of methomy] applied at 2000 h on 16 April (1.0 kg[AI]/ha) on honey bee
behavior in blooming blueberries. Cornelius, OR, 1987.
Mean number foraging
Time Temp bees/15 m of row on 18 Apmil
1100 122 treated 0(8)2/
check 20(0)
1200 10°C treated 0(1)
check 17(0)
1400 ila ee @ treated 0(2)
check 18(0)
“/Figures in parentheses are counts of bees that alighted on flowers or probed
around the bases, but never inserted their heads into the flower cups.
J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 13
1983, was again recorded (Table 8). In this case, the honey bees probed around the base of the
flowers externally and then flew off to untreated portions of the field without again landing on
a treated bloom. Apparently they were able to detect the chemical and avoid it after the initial
approach. In contrast, bees foraging the untreated check blooms inserted their heads into the
flower cups in normal foraging fashion.
DISCUSSION
It is evident from these studies that methomy] is toxic in varying degrees to the bee species
studied, and that methomyl applications affect bee -behavior. In laboratory tests of direct
toxicity, both 0.01 and 1% concentrations of methomy] caused 100% mortality of honey bees
(Harris and Svec, 1969). The topical LD, for honey bees is reported as 1.29 wg per bee (10.1
ppm) (Atkins ef al., 1981) or 0.068 tg per bee (Mansour & Al-Jalili, 1985).
Anderson & Wojtas (1986) found methomy] residues, along with other insecticides, in dead
bees obtained from beekeepers but were not able to determine if it was methomy] that killed
the bees. Flaherty et al. (1977) observed that early morning and night applications of
methomy] to citrus bloom caused little harm to honey bees. Atkins et al. (1981) reported that
methomyl] was highly toxic to honey bees present in the field during applications, though the
field hazard was low with evening applications. In our studies, the residual degradation time
(RT) in hours required to bring bee mortality down to 25% (RT 25) in cage test exposures to
field-weathered spray deposits applied at 0.3 kg (ATD/ha was < 2h. At 0.5 kg (AD) ha the RT 25
was 2 h, and at 1.0 kg (AD/ha it was 6 h. However, with the dust formulation the RT 25 was > 1
day. Materials with an RT 25 of 8 h or less are useful in terms of bee safety if applied during the
late evening or at night.
ACKNOWLEDGMENT
We thank the Washington Alfalfa Seed Commission for partial funding. The help of Lora
Rathbone and Jeff Lunden is acknowledged. Ruth Johansen assisted with the red raspberry and
blueberry investigations. We thank E. I. DuPont de Nemours and Company for analyzing
flower and nectar residues.
REFERENCES CITED
Abbott, W. S. 1925. A method of computing the effectiveness of an insecticide. J. Econ. Entomol. 18: 265-267.
Anderson, J. F. and M. A. Wojtas. 1986. Honey bees (Hymenoptera: Apidae)contaminated with pesticides and
polychlorinated biphenyls. J. Econ. Entomol. 79: 1200-1205.
Atkins, E. L., D. Kellum & K. W. Atkins. 1981. Reducing pesticidehazards to honey bees: Mortality prediction
techniques and integrated management strategies. Univ. Calif. Leaflet 1883. 23 pp.
Duncan, D. B. 1951. A significant test for differences between marked treatments in an analysis of variance. VA J.
Sci. 2: 171-189.
Flaherty, D. L., J. B. Gilley, H. K. Prieto, J. Romani & J. Soares. 1977. Pesticide honey bee kill survey during citrus
bloom in Tulare County. Am. Bee J.: 220-221, 230, 258.
Harris, C. R. & H. J. Svec. 1969. Laboratory studies on the contact toxicity of some insecticides to honeybees.
Entomol. Soc. Ontario. 100: 165-167.
Johansen, C. 1972. Spray additives for insecticidal selectivity to injurious vs. beneficial insects. Environ.
Entomol. 1: 51-54.
Johansen, C. A. 1984. Behavior of pollinators following insecticide exposure. Am. Bee J. 124: 225-227.
Johansen, C.A. and D.F. Mayer. 1989. Pollinator protection: A bee and pesticide handbook. Wicwas Press,
Connecticut. 150 pp.
Johansen, C. A., D. F. Mayer, J. D. Eves & C. W. Kious. 1983. Pesticides and bees. Environ. Entomol. 12:
1513-1518.
Mansour, S. A. & M. K. Al-Jalili. 1985. Determination of residues of some insecticides in clover flowers: A
bioassay method using honeybee adults. J. Apic. Res. 24: 195-198.
Mayer, D. F. & C. A. Johansen. 1983. Occurrence of honey bee (Hymenoptera: Apidae) poisoning in eastern
Washington. Environ. Entomol. 12: 317-320.
Mayer, D. F & C. A. Johansen. 1988. How to reduce bee poisoning from pesticides. Coop. Ext. Washington St.
Univ. WREP 15. 12 pp.
ses o a cf Johansen, J. D. Lunden & L. Rathbone. 1987. Chemical stickers and bee mortality. Am. Bee J.
: -495.
14 J. ENromot Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
THE ROBBER FLIES (DIPTERA: ASILIDAE) OF A FESTUCA GRASSLAND IN
THE OKANAGAN VALLEY, BRITISH COLUMBIA!
ROBERT A. CANNINGS
ROYAL BRITISH COLUMBIA MUSEUM
675 BELLEVILLE STREET, VICTORIA, B.C. V8V 1X4
ABSTRACT
The robber flies of a small area of grassland at Penticton, B.C. were studied;
information on 21 species in 17 genera was gathered during ten years of sporadic
collecting. The habitat, dominated by the bunchgrass, Festuca scabrella and the shrub,
Chrysothamnus nauseosus, is briefly described. Flight periods, data on prey, and
zoogeographic notes are included.
INTRODUCTION
Except for a few scattered locality records in the literature, no information on the robber
flies (Diptera: Asilidae) of British Columbia has been published. Because these flies are a
significant component of the predatory insect fauna of the province’s grasslands, I undertook a
simple study of the species present in a small area adjacent to my parents’ property near
Penticton. I was interested in examining the temporal distribution of the species, in addition to
documenting their occurrence. Such basic natural history studies are important, because
robber fly assemblages in B.C. grasslands vary considerably depending on habitat details, and
these habitats are rapidly disappearing in the Okanagan Valley.
THE STUDY SITE
Robber flies were collected in a small area of native grassland at 430 m elevation on the
Penticton Indian Reserve at the southern boundary of the West Bench Irrigation District (49°
29.5’ Nx 119° 37.5’ W) (Figs. 1, 2). The area is approximately 200 m x 300 m, bordered on the
north by irrigated gardens and orchards, and with a dirt track running east and west near the
southern edge of the rectangle.
The site is an undulating, kettle-holed terrace overlooking Penticton to the east. Penticton
has a mean July temperature of 20.1° C., a mean January temperature of -2.9° C, and 235 frost-
free days. The mean annual precipitation is 290 mm and the mean annual snowfall is 0.56 m
(Cannings et al. 1987). The soil is characterized as Osoyoos Sandy Loam (Kelley and
Spilsbury 1949); it is brown, fine to medium-textured soil with 3% gravel and 1.8% organics
by volume. It has good moisture holding capacity, and three samples gave a mean pH of 6.7
and a salinity of 0.28 dS/m (B. Maxwell in litt.).
The vegetation is dominated by Festuca scabrella (Rough Fescue) and Chrysothamnus
nauseosus (Rabbit-brush). The shrub layer is scattered and sparse, composed of Chrys-
othamnus nauseosus (Pall.) Britt. and a few individuals of Artemisia tridentata Nutt. The herb
layer is dominated by Festuca scabrella Torr., with secondary grasses such as Festuca
octoflora Walt., Bromus tectorum L., Sporobolus cryptandrus (Torr.) Gray, and Poa sandbergii
Vasey. Other herbs include Phlox longifolia Nutt., Lewisia rediviva Pursh, Fritillaria pudica
(Pursh) Spreng., Calochortus macrocarpus Dougl., Zygadenus venenosus Wats., Geum
triflorum Pursh, Arabis holboelli Hornem., and Ranunculus glaberrimus Hook. The intro-
duced pest Centaurea diffusa Lam. (Diffuse Knapweed) is abundant in disturbed areas. The
bryophyte and lichen layer, however, is well developed in much of the site, and consists
primarily of Cladonia, Peltigera, and Pohlia species.
1 This study is a contribution to the work of the Biological Survey of Canada (Terrestrial
Arthropods) and its Grasslands Subcommittee.
J. ENromov Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 15
Okanagan
River
PENTICTON
Penticton
Airport
x
®
D
=
O
&
re,)
=
iS
Y)
Figure 1. Location of the study area. The inset shows the position of Penticton at the south end of Okanagan Lake
in southern British Columbia.
16 J. ENTomMot Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
Figure 2. The study area: View south across the Rough Fescue grasslands of Penticton Indian Reserve, West
Bench, Penticton.
METHODS
From 1980 to 1988, and in early 1989, robber flies were collected sporadically during the
months that they were active (March-October) at the site. The flies were mostly caught
individually in aerial nets, but beginning in 1986 a Malaise trap was also used. This was
placed, with the collecting head facing south, along the fenceline at the northern edge of the
site. In 1988 a second trap was located at the bottom of a hollow adjacent to a dense stand of
Rosa woodsii Lindl.
The nomenclature used here follows Stone et al. (1965) for the most part; exceptions are the
splitting of Stenopogon and Scleropogon, and the use of the names Dicropaltum mesae
(Tucker) and Neomochtherus willistoni (Hine). These are changes included in a draft chapter
(Asilidae) by Fisher and Wilcox for the updated Nearctic Diptera catalogue (E.M. Fisher, in
litt.). In Stone et al. (1965) D. mesae and N. willistoni are placed in Asilus.
Described ranges are compiled from my own records and published statements in Stone et
al. (1965), Adisoemarto (1967), and Adisoemarto and Wood (1975).
17
J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
LOO
das
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yows YOTYM JOAO saiep Jo o8uwl ay JUasadal siBq [RIUOZUO]] ‘sol[J 19qQQoI YDUI isa JO ASopouayg ‘¢ aun317
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18 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
RESULTS AND DISCUSSION
Annotated List
Twenty-one species in 17 genera were collected. Collection dates and the duration of the
flight periods of each species are illustrated in Fig. 3. Collection data are listed below.
Collectors and repositories for specimens are as follows:
CNC — - Specimens donated to the Canadian National Collection, Agriculture
Canada, Ottawa, Ontario.
LV - Lynn Vasington (all specimens in UBC).
MBC_ - M. Brent Cooke (all specimens in RBCM unless otherwise designated).
RAC - Robert A. Cannings (all specimens in RBCM unless otherwise
designated).
RBCM - Royal British Columbia Museum, Victoria, B.C.
RJC - Richard J. Cannings (all specimens in UBC unless otherwise
designated).
RJH - Richard J. Hebda (all specimens in RBCM).
SGC - Sydney G. Cannings (all specimens in UBC unless otherwise
designated).
UBC - Spencer Entomological Museum, University of B.C., Vancouver, B.C.
Subfamily Dasypogoninae
Tribe Stenopogonini
Eucyrtopogon nebulo (Osten Sacken). 19.iv.1988, 1f (RAC); 20.iv.1988, 2f (RAC);
21.iv.1988, 1m (RAC); 30.iv.1989, 1m (RAC); 1.v.1989, 1f (RAC); 3.v.1989, 1m (RAC).
The genus Eucyrtopogon needs revision because there appear to be a number of
undescribed species in western North America. The identity of the West Bench specimens
is uncertain, but they resemble E. nebulo more than any other described species. This fly
lives mainly in open, dry woods from the Yukon south to California. The few West Bench
specimens were caught perched on grass as well as in the fenceline Malaise trap from 19
April to 3 May. In B.C. the species has been captured as late as 1 September (1960,
Langford [CNC]).
Holopogon stellatus Martin. 25.v.1987, 1m (RAC); 14.vi.1983, 1f (RJC); 24.vi.1988, 3m2f
(SGC); 25.vi.1988, 2m (SGC); 10.vii.1988, 3m3f (RAC); 11.vii.1986, 3m (RAC);
15.vii.1988, 3m 2f (RAC); 16.vii.1988, 3m5f (RAC); 19.vii.1986, 1m (RAC);
11.viii.1988, 2m1f (SGC).
A tiny black asilid of open woods and grasslands from southern B.C. south to California
and Nevada, H. stellatus hunts mainly from the branch tips of shrubs, as do many
members of the genus (Dennis and Lavigne 1975). This habitat preference is reflected in
the fact that all specimens were captured in the two Malaise traps set at the shrub-
grassland boundary. Specimens were recorded from 25 May to 11 August.
Scleropogon neglectus (Bromley). 10.v.1982, 1m (RAC); 12.vi.1982, Im1f (RAC);
13.vi1.1983, 3m1f (RJC); 13.vi.1987, 1m (SGC); 22.vi.1983, 1f (RIC); 30.vi.1982, Im1f
(RAC); 15.vii.1986. 1m2f (RAC); 17.vii.1988, 2m3f [1m with Formica subpolita Mayr
(Hymenoptera:Formicidae) as prey] (RAC); 1.viii.1987, 1m (RAC,RJH).
This is a large, elongate, mainly grey species occurring in grasslands from southern B.C.
and Alberta south to California and New Mexico. It tolerates a wide range of different
conditions, and in southern B.C. reaches its greatest densities in the Artemisia tridentata
stands in the hot, dry lowlands around Chopaka in the Similkameen Valley. It prefers to
forage from bare ground; on the study site most were captured along the dirt track. An ant,
a male Formica subpolita, is the only prey recorded.
Stenopogon inquinatus Loew. 10.vi.1982, 1f (RAC); 13.vi.1983, 1f (RJC); 13.vi.1987, 1f
(SGC)[RBCM]; 21.vi.1983, 1f (RJC); 22.vi.1983, 1f (RJC); 30.vi.1982, 2f (RAC);
5.ix.1983, 2f (RAC).
J. ENromMo. Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 19
Along with Machimus occidentalis, S. inquinatus is perhaps the most common and
widespread of the large robber flies in the dry forests and grasslands of southern B.C. This
heavy-bodied, reddish species ranges from northeastern B.C. south to California and east
to Manitoba and New Mexico. It is much less common on the West Bench grasslands than
in the adjacent open woods of Pinus ponderosa Doug]. (Ponderosa Pine) and Pseudotsuga
menziesii (Mirbel) Franco (Douglas-fir). The few specimens recorded were all females;
dates range from 10 June to 5 September, with all but the latter in June. One was seen
attacking the asilid Machimus occidentalis on 9 June 1982, but was not collected.
Tribe Dasypogonini
Comantella pacifica Curran. 26.11.1988, 2m (SGC); 28.111.1987, 1f (SGC); 28.111.1987, 1f
(SGC)[RBCM]; 2.iv.1984, 6m2f (RAC); 19.iv.1988, 4m7f [1f with Platycheirus coer-
ulescens (Will.) (Diptera: Syrphidae) as prey] (RAC); 20.iv.1988, 9m (RAC); 21.iv.1988,
4m1f (RAC); 22 iv.1988, Im1f (RAC); 28.iv.1989, 1m (RAC); 29.iv.1989, 1m (RAC);
30.iv.1989, 2m1f (RAC); 1.v.1989, 1m (RAC); 3.v.1989, 1m (RAC); 8.x.1984, 2f (SGC);
8.x.1984, 1f (SGC) [RBCM]; 13.x.1986, 2f (SGC), 1f (SGC)[RBCM]; 22.x.1983, 2m
(SGC), 6m3f (RAC).
Known in Canada only from the Okanagan Valley, C. pacifica ranges south into the
grasslands of Washington. Penticton is the type locality (4 April 1919, E.R. Buckell
[CNC]). The species perches both vertically on grass and horizontally on the ground
while hunting. The known flight period on the West Bench is divided into an early
segment (26 March to 3 May) and a later one (8 to 22 October). The only prey recorded is
the hover fly Platycheirus coerulescens, which is common along the dirt track in April.
Cophura brevicornis (Williston). 30.vi.1982, 1f (RAC)
This species ranges from the Chilcotin region of central B.C. south to California,
Colorado, and Nebraska. In B.C., C. brevicornis is predominantly a denizen of open, dry
woods; it is probably a wanderer to the study area. The single specimen was collected on
30 June 1982. It is rather common in the Ponderosa Pine and Douglas-fir woods on the
surrounding hills in July; the latest B.C. date is 24 August (1964, Princeton [CNC]).
Lestomyia sabulona (Osten Sacken). 11.v.1983, 1m1f in copula (SGC); 17.v.1985, 3m (RJC);
20.v.1984, 4m (RAC); 21.v.1984, 3m2f (RAC); 22.v.1987, 1f (RAC); 29.v.1984, 2m1f
(RJC), Imlf (RJC)[RBCM]; 30.v.1984, 1m (RJC); 3.vi.1986, 1m (RJC).
L. sabulona is a small, pale robber fly ranging from the grasslands of Alberta and the
southern Okanagan Valley of B.C. south to California and Wyoming. The recorded flight
period is early and short, from 11 May to 3 June; a single mating was noted on 11 May.
Tribe Dioctrini
Dioctria pusio Osten Sacken. 10.vii.1988, 1f (RAC).
In B.C. Dioctria pusio is generally found in dry woodlands; it ranges from the southern
fringes of the province south to California and Colorado. The single specimen was caught
on 10 June 1988 in the fenceline Malaise trap. At Robson, in the Kootenay district, where
the largest series of the species in B.C. was captured, records range from 13 June to 23
August [CNC].
Dicolonus nigricentrus Adisoemarto and Wood. 18.v.1987, 1f (SGC).
A rather rare grassland species known in B.C. from the Chilcotin region south into the
Okanagan and Similkameen valleys, D. nigricentrus ranges into Washington and northern
Idaho. The single specimen is from the fenceline Malaise trap on 18 May 1987; other B.C.
records range from 3 May (1987, Osoyoos, C.S. Guppy [RBCM]}) to 29 June (1923,
Keremeos, C.B. Garrett [CNC]).
Eudioctria sackeni (Williston). 14.vi.1987, 2f (SGC); 24.vi.1988, 1m2f (SGC); 10.vii.1988,
Im (RAC); 11.vii.1986, 2m (RAC); 14.vii.1986, 2m2f (RAC); 19.vii.1986, 2m (RAC).
This is acommon species of forests and open areas in the lowlands of southern B.C. from
Vancouver Island to the Rocky Mountains; it ranges south through Idaho and western
Montana to California. All specimens are from Malaise traps between 14 June and 19
20 J. EnTomo_ Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
July. Two colour morphs are represented, designated sackeni and rivalis by Adisoemarto
and Wood (1975). The character differences are most pronounced in males. The sackeni
morph has a yellow-white face, yellow facial bristles, extensive orange markings on the
legs, and in the male, the wings are orange basally, and grey apically. The rivalis morph
has a silver face in the male, brassy in the female. The facial bristles are black, the wings
are grey, and the legs are black with only the bases of the tibiae and apices of femora
yellow. Sackeni is the more common morph, outnumbering rivalis 2 to 1 in the West
Bench collections.
Myelaphus lobicornis (Osten Sacken). 4.vi.1983, 4m (SGC), 2m1f (RAC); 7.vii.1983, 1f
(RAC); 10.vi.1982, 2m (SGC), 2m (SGC)[RBCM], 1f (SGC)[CNC], 1m2f [1 pr in
copula] (RAC), 1m (RAC)[CNC] 3m1f (MBC), 1m (MBC)[CNC]; 12.vi.1982, 1m
(RAC); 13.vi.1987, 1f (SGC); 14.vi.1983, 1m (RJC); 17.vi.1987, 1m (SGC); 22.vi.1983,
Im (RJC); 25.vi.1984, 5m (RAC).
All Canadian specimens but one (Dutch Creek, Columbia Lake, 16 July 1967 [RBCM])
are from Penticton. The species ranges south to California, Nevada and Utah. Records in
the study area are from 4 to 25 June; since the periods before and after these dates were
well-collected in several years, the flight period is likely restricted to June. M. lobicornis
was collected only in open stands of rabbit-brush, where it looks and behaves much like
an ichneumonid wasp. It lacks extensive bristles or body hairs, has a black head and
thorax, and has unusually long antennae. The wings are blackish, the abdomen red, and
the legs yellow. It flies slowly, with the abdomen and long legs dangling.
Subfamily Laphriinae
Tribe Laphriini
Laphria sadales Walker. 16.vii.1988, 1f (RAC)
Laphria species are characteristic of forests, and L. sadales is no exception. It shows a
typical Boreal distribution across the northern forests of North America, with a southerly
extension along the western mountains as far as California and Wyoming. The single
specimen captured in the fenceline Malaise trap on 16 July 1988 was undoubtedly a
wanderer from the Ponderosa Pine woodlands 1 km to the west.
Subfamily Asilinae
Tribe Apocleini
Efferia albibarbis (Macquart). 4.viii.1986, 1m (RAC)
This species is one of the most widespread of North American asilids, ranging across the
continent and south to Guatemala. In Canada, however, it occurs only in the southern
Okanagan Valley and on the beach dunes along Lake Erie in southern Ontario. The lone
specimen caught (4 August 1986) was clearly out of the species’ usual Okanagan habitat,
which is the sandy benchlands around Oliver and Osoyoos. There is suitable habitat near
the study area, however, that has yet to be investigated; it may support a small population.
Records from the southern Okanagan Valley range from 9 June (1958, Osoyoos, H.& A.
Howden [CNC] to 27 July (1953, Osoyoos, J.R. McGillis [CNC)).
Efferia benedicti (Bromley). 4.vi.1983, 2f (SGC); 9.vi.1982, 1m [with Formica subpolita
Mayr (Hymenoptera: Formicidae) as prey] (RAC); 10.vi.1982, 3f (RAC); 12.vi.1982, 1m
Lf (RAC); 16.vi.1983, 1m (RJC); 30.vi.1982, 1m [with Astata bakeri Parker (Hymenop-
tera:Astatidae) as prey] (RAC); 9.vii.1988, 1m (RAC); 17.vii.1988, 1m 1f (RAC);
3.viii.1986, 1f (RAC); 17.viil.1988, 1f (RAC).
Ranging from southern B.C. south to California and Arizona, E. benedicti is one of the
most abundant robber flies of the cordilleran grasslands. In the study area it has been
collected from 4 June to 17 August. Two prey species, both Hymenoptera, are recorded
from these collections - the sphecoid wasp Astata bakeri, and a queen of the common
grassland ant Formica subpolita. Mating was recorded on 13 May.
J. ENromMot Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 ZI
Efferia coulei Wilcox. 11.v.1983, 2f (SGC); 13.v.1983, 4m6f [1 pr in copula] (SGC);
16.v.1984, 1m (SGC); 17.v.1985, 2m (RJC); 21.v.1984, 2m (RAC); 22.v.1987, 3m3f
(RAC); 26.v.1987, 1f (RAC): 28.v.1984, 1m (RJC); 3.vi.1986, 3m1f (RJC); 4.vi.1983,
3m6f (RAC); Im1f (RAC)[CNC], 1m1f [1f with Serica sp. (Coleoptera: Scarabaeidae) as
prey] (SGC); 5.vi.1983, 1m (SGC); 9.vi.1982, 1m2f [1f with Salda buenoi (McD.)
(Hemiptera: Saldidae) as prey] (RAC); 10.vi.1982, Im6f (RAC), 3f (RAC)[CNC];
12.vi.1982, 2m3f (RAC); 13.vi.1983, 1m (RJC); 13.vi.1987, 1f (SGC); 24.vi.1984, 5f
(RAC): 25.vi.1984, 2m (RAC), 2f (MBC).
E. coulei is one of the more common species of the northern mesic intermontane
grasslands, ranging from the Chilcotin region of central B.C. south to central Washington.
It is strictly a spring species; records on the West Bench are from 11 May to 25 June.
Recorded prey species are the shore bug Salda buenoi and a species of the scarab beetle
genus Serica.
Efferia harveyi (Hine). 1.viii.1987, 2m3f (RAC, RJH); 13.viii.1986, 3m3f (SGC), 2m
(SGC)[RBCM]; 22.viii.1987, 6m1f (RAC); 23.viii.1987, 3m2f (RAC); 24.viii.1983,
4m2f (RAC), 1f (RAC)[UBC]; 30.viii.1983, 9m4f [1f with Lasius pallitarsus
(Provancher) (Hymenoptera: Formicidae) as prey] (RAC), 3m (RAC)[CNC];
31.viii.1983, 4m1f (RAC), 1m (RAC)[UBC]; 1.1x.1983, 2m4f (RAC); 2.1x.1983, 4m1f
(RAC); 3.ix.1983, 2m4f (RAC), 2m2f (RAC)[UBC]; 5.ix.1983, 12m2f [1m with Villa sp.
(Diptera: Bombyliidae) as prey, 1m with Platymyia confusionis (Sellers) (Diptera:
Tachinidae) as prey] (RAC); 2m (RAC)[CNC], 2m (RAC)[UBC]; 6.ix.1983, 3f
(RAC)[CNC]; 6.ix.1980, 1f (SGC); 26.1x.1987, 1f (RAC).
A common late summer and autumn species, E. harveyi ranges from the Chilcotin
grasslands south through the Nicola and Okanagan valleys to California. It is at home in a
variety of habitats - lowland sandy habitats dominated by Purshia tridentata and Aristida
longiseta, Agropyron spicatum grasslands with Artemisia tridentata, and mesic Festuca
grasslands.
Efferia staminea (Williston). 30.vi.1982, 1m (RAC)
This species is more or less restricted to the cooler, more mesic grassland sites in southern
B.C. and is nowhere common. It ranges south to Colorado, and also occurs in southern
Alberta, but is rare there. A single specimen was captured on the West Bench on 30 June
1982. Records from other parts of the valley range from 12 June (1919, Vaseux Lake, E.R.
Buckell [CNC]) to 4 August (1915, Okanagan [RBCM]). Lavigne and Holland (1969)
state that although the species is euryphagic, it has a preference for dipterous prey.
Proctacanthus milbertii Macquart. 1.viii.1987, Im1f (RAC, RJH); 3.viii.1986, 2m1f (RAC);
4.viii.1986, 1f [with Paratiphia nevadensis Cam. or claripennis Cam. (Hymenoptera:
Tiphiidae) as prey] (RAC); 10.viii.1982, 2m (SGC); 13.viii.1986, 2m [1m with Vespula
arenaria (Fab.) (Hymenoptera: Vespidae) as prey] (SGC); 17.viii.1988, 1m (RAC);
18.vili.1986, 1m (SGC); 22.vili.1987, 2m (RAC); 24.viii.1983, 1m (RAC); 30.viii.1983,
Im, 2f (RAC); 31.viii.1983, 1m [with Melissodes sp. (Hymenoptera: Anthophoridae) as
prey] (RAC); 1.1x.1983, Im2f (RAC); 2.ix.1983, 1m (RAC); 3.ix.1983, lmlf (RAC);
5.1x.1983, 2m1f (RAC).
A very large, grey asilid with.a wide geographical range, P. milbertii occurs from coast to
coast in the U.S.; in Canada it is restricted to the southern limits of B.C., Ontario, and
Quebec. In B.C. it is strictly a grassland species. In the study area it flies mainly in August
(1 August - 5 September). Identified prey here are a yellow jacket wasp (Vespula
arenaria), an anthophorid bee, (Melissodes sp.), and a tiphiid wasp, (either Paratiphia
nevadensis or P. claripennis).
22 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
Tribe Asilini
Dicropaltum mesae (Tucker). 21.v.1987, 1f (RAC); 22.v.1987, 1m (RAC); 26.v.1987, 2f
(RAC); 3.vi.1986, 1f (RIC); 4.vi.1983, 1f (RAC); 9.vi.1982, 1m1f [in copula] (RAC);
10.vi.1982, Im2f (RAC); 12.vi.1982, 1m2f (RAC); 13.vi.1987, 1f (SGC); 14.vi.1987,
Im1f (SGC); 26.vi.1981, 1f (SGC); 1.vii.1980, 1m (SGC), 11.vii.1986, Im1f (RAC);
15.vii.1986, 2m2f (RAC); 16.vii.1988, 1m (RAC); 17.vii.1988, 1f (RAC); 19.vii.1986, 1f
(RAC).
A common little golden species inhabiting B.C. grasslands from the Chilcotin region
southward to the Okanagan Valley, D. mesae also ranges east into Alberta and south to
Utah and Kansas. The recorded flight dates in the study area are from 21 May to 19 July,
which is probably a good estimate of the extremes of the flight period in the study area.
Mating was recorded on 9 June.
Machimus occidentalis (Hine). 22.v.1987, 1m (RAC); 4.vi.1983, 7m3f (RAC), 2f (SGC);
6.vi.1981, 1m (SGC); 9.vi.1982, Im (RAC); 10.vi.1982, 4m2f (RAC); 12.vi.1982, 1f
(RAC); 14.vi.1987, 1m (SGC); 16.vi.1983, 2m (RJC); 25.vi.1984, 3ml1f (RAC);
25.v1.1988, 1f (SGC); 30.vi.1982, 1m (RAC); 3.vii.1981, 1f (SGC).
This is one of the most common robber flies of open, dry forest and associated grassland
in the western cordillera. In B.C. it is common throughout the south from the Rocky
Mountains to southern Vancouver Island at low and middle elevations. It ranges south to
California and Nevada. It is a spring and early summer species; the majority of West
Bench records are from June (22 May - 3 July).
Neomochtherus willistoni (Hine). 16.vii.1988, 1m (RAC); 17.vii.1988, 1m (RAC);
18.vii.1986, 3m (RAC); 19.vii.1986, Imlf (RAC); 1.viii.1987, 2m1f (RAC, RJH);
2.viii.1987, 2m1f (SGC); 3.viii.1987, 3m (SGC); 16.viii.1988, 1f (RAC); 17.viii.1988,
lm (SGC); 22.viii.1987, 4m2f (RAC); 23.viii.1987, 1f (RAC), 1f (SGC); 24.viii.1987,
Imlf (RAC); 27.viii.1980, 1m (RJC); 31.viii.1983, 1m1f (RAC); 3.ix.1983, 1f (RAC);
6.ix. 1982, 1f (LV).
Similar in general appearance and behaviour to Machimus occidentalis, N. willistoni has
an almost identical distribution in B.C. However, it occurs only as far south as Washing-
ton. Unlike M. occidentalis, it is a late summer species; records on the West Bench range
from 16 July to 6 September.
Zoogeography
1. Faunal Elements
Grouping the twenty-one robber fly species into faunal elements based on their geographi-
cal distribution patterns produces a generalized picture of the assemblage’s geographic origins.
These faunal elements are derived from range patterns observed in this study, but follow
similar treatments in Cannings and Cannings (1987) and Cannings et al. (1987). The species
composition of the assemblage reflects a distinct western origin of the fauna (Fig. 4).
Cordilleran (28.5%). Species of mountain forests of western North America. Six of the 21
species inhabit open forests in the valleys and plateaus of the western mountains, typically
from B.C. south to California. These species also occur in adjacent grasslands to some
extent, some more abundantly than others. Included here are Dioctria pusio, Eucyr-
topogon nebulo, Eudioctria sackeni, Holopogon stellatus, Machimus occidentalis, and
Neomochtherus willistoni.
Intermontane (28.5%). Species of plateau and valley grasslands in the western mountains. Six
species, Comantella pacifica, Dicolonus nigricentrus, Efferia benedicti, E. coulei, E.
harveyi, and Myelaphus lobicornis are restricted to these grasslands. C. pacifica, D.
nigricentrus, and E. coulei have rather restricted distributions in the northern grasslands
of the Cordillera, from Washington north into the Chilcotin region of B.C. This Northern
Intermontane element can be considered a subset of the Intermontane element, because it
is distinct in its northern character. It is not treated separately in Fig. 4.
J. ENTomMoL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 23
Western (28.5%). Species of the western mountains, associated lowlands and, to varying
degrees, adjacent areas of the Great Plains. Cophura brevicornis, Dicropaltum mesae,
Efferia staminea, Lestomyia sabulona, Scleropogon neglectus, and Stenopogon inqui-
natus are western species whose ranges extend east of the Rocky Mountains. Some reach
only the western parts of the Great Plains, but others, such as C. brevicornis (Nebraska),
D. mesae (Kansas), and §. inguinatus (Minnesota) range further east. Were it not for an
extensive Great Plains component in their ranges, these species would be considered part
of the Cordilleran or Intermontane elements. Only C. brevicornis and S. inquinatus are
predominantly open forest species in the west.
Southern (9.5%). Species ranging transcontinentally south of the Boreal Forest, at least in the
U.S.; in Canada only in extreme southern areas. Proctacanthus milbertii and Efferia
albibarbis, in B.C. at least, are strictly grassland species. Both enter Canada only in
southern B.C. and Ontario.
Boreal (5%). Species ranging transcontinentally in the Boreal Forest and southward in the
Percentage of species collected
western mountains to varying degrees. Laphria sadales is the sole Boreal species
recorded; it ranges in the northern forests from B.C. east to Quebec . The presence of L.
sadales in the study area is probably accidental; it is undoubtedly a visitor from nearby
woodland. The Boreal faunal element cannot be expected to contribute to the origin of the
western grassland fauna.
Boreal Cordilleran Western Intermontane Southern
Figure 4. Origins of the fauna: percentage of species from different faunal elements, based on distribution pattems.
The bars representing each element are further divided to show the general habitat preferences of the species
included.
(stippled = g-assland and woodland; clear = grassland only)
24 J. ENToMot Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
2. Habitat
If Laphria sadales is eliminated from the list (its presence likely is accidental), 18 of the 20
remaining species are restricted to the grasslands and open, dry forests of western North
America. The other two, Proctacanthus milbertii and Efferia albibarbis, are Southemn
elements and, in B.C. at least, are inhabitants of grasslands only. In the East and South,
however, they may be found in regions where true grasslands do not exist, especially in open,
sandy areas.
Forty-three per cent (9 species) of the assemblage lives in both open woodland and
grassland (Fig. 4). Indeed, these species may be more common in the former habitat than in the
latter; Stenopogon inquinatus, Cophura brevicornis, and Eudioctria sackeni are examples.
Microhabitat clearly plays an important role in the local distribution of many robber flies.
Local differences in climate, soil type, and vegetation determine the presence of species in any
small area of grassland. For example, the moister, darker soils associated with the cooler
climatic regimes of grasslands above about 500 m in the southern B.C. Interior often are
characterized by forbs such as Balsamorhiza sagittata (Pursh) Nutt. (Balsamroot) and Lupinus
sericeus Pursh (Silky Lupine) and support several abundant species of asilids not found on the
West Bench. Cyrtopogon willistoni Curran and Stenopogon rufibarbis Bromley are good
examples. Several other species, common elsewhere, are absent from the study area. Procta-
canthus occidentalis Hine is the dominant member of the genus in the grasslands of the Oliver-
Osoyoos area; the soil there is usually coarse and sandy, and plants predominating include
Purshia tridentata (Pursh) DC. (Antelope-brush) and Aristida longiseta Steud. (Red Three-
awn Grass). P. milbertii, the West Bench species, occurs there as well, but in much lower
numbers. The two species are more or less temporally separate, with P. occidentalis active in
June and July and P. milbertii in August and September. No Leptogaster species have been
recorded from the West Bench, although at least one species (near L. fornicata Martin) is
present in the grasslands growing on the coarser, better drained soils further south. Leptogaster
is a genus of small, elongate, rather fragile asilids (Asilidae: Leptogastrinae) that, in British
Columbia, at least, perch on, and hunt from, grasses. Efferia albibarbis prefers sandy soils, and
is common around Osoyoos Lake; the single specimen from the study area was not in its
typical habitat. An undescribed species of Efferia common in the drier soils of Vaseux Lake to
the south and Kalamalka Lake to the north is not present on the West Bench site. This species
evidently is closely related to E. coulei, and like E. coulei is a spring species; its requirement
for a different microhabitat is likely one of the barriers that separates them. Efferia staminea 1s
rare in the study area; it is more common in the drier habitats dominated by Agropyron and
Stipa grasses where the undescribed Efferia is found. E. benedicti is more common on the West
Bench than its close relative E. staminea, but not as abundant as E. coulei. The preferred
habitat of E. benedicti in the southern Okanagan is the dry, silty soil favoured by Artemisia
tridentata. E. harveyi is common in both types of habitat.
Within the study area a few species show particular preferences for certain sites. Myelaphus
lobicornis is restricted to the large clusters of Chrysothamnus nauseosus on. the northeastern
border of the area. It uses these shrubs as perching sites, but also lands.on grass stems. Its
particular relationship to the shrub is unclear, but the only other known locality for the species
in B.C. and Canada is Dutch Creek near Columbia Lake where Rabbit-brush is also the
dominant grassland shrub. Eudioctria sackeni, an example of aspecies mainly associated with
shrubs and trees in open woodland (where it uses these larger plants for perching sites), was
captured only in the two Malaise traps, both set adjacent to the shrub/grassland interface.
3. Phenology |
Figure 3 illustrates that although June and July are the months with most species present,
some flies have flight periods temporally separate from those of other species. Particularly
striking is the observation that several closely related species, or species of similar size and
habits (and thus perhaps potential competitors), fly at different times during the season. Thus,
J. ENromMo. Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 25
Machimus occidentalis is active mainly in June and the related Neomochtherus willistoni flies
mostly in August; their flight periods do not overlap. The two appear to fill very similar niches.
Likewise, the three most common species of Efferia - E. coulei, E. benedicti, and E. harveyi -
follow each other from spring to autumn, evidently doing similar things in the same place. All
three species hunt from the ground, or from very low on grass stems. Presumably the
separation of their flight periods allows the three species to live in the same habitat without
much competition. Other behavioural differences may also be important. Lavigne and Dennis
(1985) studied three sympatric Efferia species in Mexico and found that each foraged at
different heights in the vegetation, predominantly at different times of day, and that the type of
prey taken by each species exhibited very little overlap. They speculated that these factors
allowed the three species to coexist. On the West Bench, prey selection was not observed often
enough to be of use in this context. Comantella pacifica hunts in a similar manner to these
Efferia species, and takes prey of a similar size to at least that of E. coulei. Comantella’s flight
period is very early and very late, bracketting all species of Efferia. The spring specimens
appear fresh, suggesting to some students that Comantella species emerge in both the late fall
and early spring. In Colorado, James (1937) felt that there was a partial emergence of C. fallei
Back in the fall, with a continuation of the emergence the following spring. Déhnis and
Lavigne (1975), however, state that in Wyoming adults have been collected from beneath
rocks in early March, indicating that they may overwinter in that stage. Whatever the
mechanism, the very early and late flight periods enable C. pacifica to be active when no other
robber flies can compete with them. Lestomyia sabulona and Dicropaltum mesae, although not
closely related, are similar in size and hunting behaviour. The former is almost completely
restricted to a May flight period; the latter, although first seen in May, is predominantly active
in June and July.
As in many insects, there is a tendency in some species for males to emerge earlier in the
season than females, although the data is too spotty to make significant analyses of this
phenomenon. It is most noticeable in Neomochtherus willistoni, Myelaphus lobicornis and
Lestomyia sabulona, and to a lesser degree in Proctacanthus milbertii and Holopogon
stellatus. Females appear more common early in the flight period in Dicropaltum mesae and
Efferia benedicti. Females seem to fly later in the season than males in some species; this is
especially evident in the genus Efferia. Most species do not show major peaks in flight times,
but L. sabulona evidently is most abundant at the end of the third week of May, M. lobicornis
in the second week of June, E. coulei in the first two weeks of June, Efferia harveyi in the last
week of August and the first week of September, and Machimus occidentalis in the first two
weeks of June.
ACKNOWLEDGEMENTS
I thank S.G. and R.J. Cannings (Dept. Zoology, University of British Columbia, Vancouver)
for collecting many of the specimens used in this study and for help in preparing the figures.
S.G. Cannings (Vancouver), C.S. Guppy (Royal B.C. Museum, Victoria), and E.M. Fisher
(California Dept. Food and Agriculture, Sacramento) criticized the manuscript. R.T. Ogilvie
and L. Pavlick (Royal B.C. Museum) identified some of the plants noted, and B. Maxwell
(B.C. Ministry of Environment) examined the soil samples. Prey specimens were identified by
A.T. Finnamore (Provincial Museum of Alberta, Edmonton), B. Cooper and R. Vockeroth
(Biosystematics Research Centre, Ottawa), C. Guppy (Royal B.C. Museum, Victoria), A.
Francoeur (Université du Quebéc, Chicoutimi), and J. Lattin (Oregon State University,
Corvallis).
REFERENCES
Adisoemarto, A. 1967. The Asilidae (Diptera) of Alberta. Quaestiones Entomologicae 3:3-90.
Adisoemarto, A. and D.M. Wood. 1975. The Nearctic species of Dioctria and six related genera (Diptera:
Asilidae). Quaestiones Entomologicae 11:505-576.
Cannings, R.A. and S.G. Cannings. 1987. The Odonata of some saline lakes in British Columbia, Canada:
ecological distribution and zoogeography. Adv. Odonatol. 3:7-21.
Cannings, R.A., R.J. Cannings, and S.G. Cannings. 1987. The birds of the Okanagan Valley, British Columbia.
Royal B.C. Museum, Victoria. 420 pp.
26 J. ENTOMOL Soc. BRrrT. COLUMBIA 86 (1989), SEPT. 30, 1989
Dennis, D.S. and R.T. Lavigne. 1975. Comparative behavior of Wyoming robber flies II (Diptera: Asilidae). Univ.
Wyoming Agric. Exp. Sta. Sci. Monogr. 30:1-68.
James, M.T. 1937. The genus Comantella Curran (Diptera: Asilidae) Pan-Pacific Entomol. 13:61-63.
Kelley, C.C. and R.H. Spilsbury. 1949. Soil survey of the Okanagan and Similkameen valleys, British Columbia.
Report No. 3 of the British Columbia survey. B.C. Dept. Agriculture and Dominion Dept. Agriculture,
Ottawa. 88 pp.
Lavigne, R.J. and FR. Holland. 1969. Comparative behavior of eleven species of Wyoming robber flies (Diptera:
Asilidae). Univ. Wyoming Agric. Exp. Sta. Sci. Monogr. 18:1-61.
Lavigne, R.J. and D.S. Dennis. 1985. Ethology of three coexisting species of Efferia (Diptera: Asilidae) in
Mexico. Proc. Entomol. Soc. Wash. 87(1):146-160.
Stone, A., C.W. Sabrosky, W.W. Wirth, R.H. Foote, and J.R. Coulson. 1965. A catalogue of the Diptera of America
north of Mexico. U.S. Dept. Agriculture, Agriculture Handbook No. 276. Washington, D.C. 1696 pp.
BIOLOGY OF Erythroneura elegantula AND E. ziczac (HOMOPTERA:
CICADELLIDAE) ON Vitis vinifera INSOUTHCENTRAL WASHINGTON
J. D. WELLS! AND W. W. CONE
IRRIGATED AGRICULTURE RESEARCH AND EXTENSION CENTER
WASHINGTON STATE UNIVERSITY
PRossER WA 99350
ABSTRACT
The western grape leafhopper, Erythroneura elegantula Osbom, and the Virginia
creeper leafhopper, Erythroneura ziczac Walsh, were the only species of leafhoppers
found colonizing grapevines, Vitis vinifera (L.), in southcentral Washington. Other
Cicadellids collected did not colonize. Where the mymarid parasitoid, Anagrus epos,
was found, the predominant leafhopper was E. elegantula. In the absence of A. epos, E.
ziczac seemed to be the more abundant. E. ziczac quickly dominated a mixed population
of both species in a greenhouse. On heavily damaged grape leaves, E. ziczac eggs
remained surrounded by green tissue whereas E. elegantula eggs were not. This
suggests the presence of a repellent or anti-feedant with E. ziczac eggs. Development
time for E. elegantula averaged 402.6 D° which is much shorter than previously
published times, and for E. ziczac averaged 390.5 D°.
Keywords: Erythroneura elegantula, Erythroneura ziczac, Vitis vinifera, wine grapes,
leafhopper biology
INTRODUCTION
Doutt and Nakata (1973) believed that Erythroneura elegantula, the western grape leafhop-
per (WGLH) infested Vitis californica Bentham in California before the cultivation of V.
vinifera. It was probably introduced into the Pacific Northwest on cultivated grapevines.
Wolfe (1955) described WGLH as the leading insect pest of grape in Washington; it has the
same distinction in California (Jensen and Flaherty, 1981).
Erythroneura ziczac, the Virginia creeper leafhopper (VCLH) was described by Walsh from
a single specimen collected in Illinois (Beamer, 1936). It was recognized early as a minor pest
of grape (Wirtner, 1904) and apple (DeLong, 1931), and as a principal insect pest of Virginia
creeper and Boston ivy (Fairbairn, 1928; Pepper and Mills, 1936). VCLH occurs throughout
the U.S. and southern Canada (Metcalf, 1968) but like WGLH is probably new to the Pacific
Northwest,which has no native Vitaceae (Hitchcock and Cronquist, 1973). VCLH was
recognized as the worst pest of V. vinifera grapes in British Columbia by McKenzie and Beirne
in 1972.
1Current address: Dept. of Biological Sciences, Univ. of Illinois at Chicago, Chicago, IL 60680.
J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 PH
MATERIALS AND METHODS
Collection and identification.
Erythroneura adults and nymphs were collected in June and July of 1983 on V. vinifera in
vineyards at the Irrigated Agriculture Research and Extension Center, Prosser, and also at
Paterson, Grandview, and Cold Creek (Fig. 1). Fifty leaves were collected, placed in plastic
bags, and examined in the laboratory. Sweep net samples, taken from at least 200 m along one
side of vineyard rows during each of four visits to each site, were also placed in bags and
examined in the laboratory. Identification was based on 150 males chosen randomly from
about 10,000 Erythroneura adults taken, plus 83 males reared from nymphs. These were
dissected for identification, using the method of Oman (1949) and the keys of Beamer (1936).
* = E. elegantula
O = E. elegantula and E. ziczac
+ = E. elegantula and A. epos
+
Hl
It
. elegantula, E. ziczac and A. epos
¢3 Paterson
WASHINGTON *7
Cole OREGON
Figure 1.Known distribution of E. elegantula, E. ziczac and A. epos on southcentral
Washington V. vinifera.
28 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
Temporary Food Plants.
Overwintering Erythroneura adults were collected in Tulgren funnel samples of vineyard
debris, about 20 kg each, from Prosser, Grandview and Cold Creek on 28 Feb., 1983.
Erythroneura spp. were not found in similar samples taken on 15 Apr., a date preceding V.
vinifera bud break. At that time vegetation within and up to 200 m from the edges of vineyards
plus a vineyard at Paterson, was sampled with a sweep net. Plants yielding Erythroneura spp.
were identified using the keys of Hitchcock and Cronquist (1973).
Survey for Erythroneura spp., arthropod predators and parasitoids.
At least 50 m of each vineyard margin was sampled with a sweep net and 200 leaves taken
during Sep. and early Oct. 1984 at 12 vineyards. The sites are shown in Fig. 1. Leaf and sweep
net samples were also collected during the growing seasons of 1983 and 1984 at Prosser and
Cold Creek. Vine leaves were examined for the presence of Erythroneura immatures and
evidence of A. epos. Cicadellid species were determined using the keys of Oman (1949),
Beirne (1956), and Beamer (1936). Other Arthropoda were sent to appropriate authorities for
identification. Voucher specimens have been placed in the insect collection at Washington
State University, Pullman.
Development and Mortality of Immature Erythroneura spp.
The development rate and mortality of immature WGLH and VCLH in the absence of
natural predators and parasitoids were compared on vines at Prosser in Jul., 1985. Air
temperature was recorded at a height of 1.5 m. The hourly values used were averages of field
data measured every 10 sec. Using the developmental threshold of 10.3°C (50.5°F) determined
for WGLH in California (Cate, 1975), physiologic time was calculated as the area under a
temperature curve using a Fortran computer program.
Eggs of known age were obtained by confining 15-20 individuals of each species in leaf
cages for 24 h. Mature, exposed leaves were selected free from Erythroneura spp. damage to
avoid previously laid eggs. Upon selecting a mature leaf with no indication of leafhopper
feeding injury, the shoot was cut leaving that leaf terminal. A single leaf cage similar to that
used by Pickett et al. (1987) was tied on the shoot and leafhoppers added. Cage effect on leaf
temperature was examined using an Omnidata® model DP212 2-channel temperature
recorder (+0.2°C) to measure air temperature beneath a caged leaf and a neighboring leaf.
Temperatures were recorded simultaneously every 0.5 h for 160 h.
Nymphs were counted when they reached instar V. Some were then placed individually on
the underside of a leaf in a clip-on cage of 2.5 cm inner diam. modified from DeBach and
Huffaker (1971). Data from leaf cages found later to contain arthropod predators were not
used. The number of eggs deposited was determined by counting the unhatched eggs and
empty chorions with a dissecting microscope (20X). The nymphs in the clip-on cages were
examined daily. The date of death or imaginal molt, and the sex of emerged adults were
recorded.
RESULTS AND DISCUSSION
The western grape leafhopper (WGLH), and the Virginia creeper leafhopper (VCLH), were
the only Erythroneura pests of Vitis vinifera found. No immature cicadellids of other species
were found on grapevines and 11 other species of adult leafhoppers identified, caused no
noticeable damage. The characters distinguishing WGLH and VCLH in the field are shown in
Fig. 2,
E. comes and E. elegans, both reported from Vitis spp. in Washington (Frick, 1952; Wolfe,
1955; Capizzi et al., 1985) were not found. Some species of Erythroneura are difficult to
distinguish from E. comes, and certain early workers considered them to be variations of that
leafhopper (Robinson, 1926). We believe that difficulty in identifying Erythroneura spp. has
J. ENtomov Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 29
Figure 2.Characters for distinguishing Erythroneura spp. found in southcentral
Washington vineyards are: E. ziczac adults (A) have dark lateral pronotal spots;
nymphs III-V (B) have red spots on dorsum. E. elegantula adults (B) and nymphs
(D) have no dark pigmentation on the dorsum.
resulted in incorrect reports of E. comes from west of the Rocky Mountains. E. comes has been
reported from throughout the western U.S. and Canada (Gillette, 1898; Essig, 1926; Knowl-
ton, 1933; Wolfe, 1955), but those authors did not describe distinguishing characters.
Moreover, current workers in Washington, Oregon, and California have not seen E. comes
(P.W. Oman and R. L. Doutt, 1985, pers. comm.), and no specimen labeled E. comes collected
in the West was found in the collections of Washington State University or Oregon State
University. The University of California at Berkeley, had a single specimen labeled E. comes,
collected there in 1914 (J. Chemsak, 1985, pers. comm.). That specimen was found to be
female and so could not be identified to species.
Temporary Food Plants.
In areas with cold winters, Erythroneura spp. overwinter as adults in plant debris, most
often in the leaves of the host plant. Overwintering forms may become active during any brief
warm period and move to temporary food plants. They are often found on temporary food
plants just before and after their host plants growing season.
30 J. ENromot Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
Cate (1975) conducted a spring survey and found that Rubus spp., Prunus dulcis, sagebrush
and storksbill served as temporary food plants for WGLH. Adults were found on dandelion,
pear, Medicago spp., willows, hops and in greatest density on balsam-root, Balsamorhiza
sagittata. Immature forms were not found on these plants. WGLH’s apparent preference for
balsam-root as a temporary food plant suggests that it might serve as a trap crop. Clean culture
in vineyards could increase WGLH movement to balsam-root in early spring.
VCLH was collected on dandelion only, which was also found to be a preferred temporary
food plant by McKenzie and Beirne (1972). Since it occurred on V. vinifera in rather barren
areas, it probably had other temporary food plants. VCLH adults that had escaped from colony
Cages were observed feeding on hops in a greenhouse. After WGLH was found in large
numbers on balsam-root, an effort was made to sample balsam-root near vineyards with
VCLH. However, no balsam-root was found within one km of vineyards containing VCLH.
Both leafhopper species had other host plants near Prosser. WGLH bred on Concord grapes,
Vitis labrusca and VCLH on Virginia creeper, Parthenocissus quinquefolia.
Survey for Erythroneura spp. and the parasitoid, Anagrus epos.
The known distribution of Erythroneura spp. and A. epos on Washington grapevines in 1984
is shown in Fig. 1. WGLH is ubiquitous on grapevines in southcentral Washington. VCLH was
not found on Vitis spp. in the Yakima Valley proper, although it was reported from a vineyard at
Sunnyside, (Wolfe, 1955). A. epos was abundant on grapevines in the lower Yakima Valley and
a single parasitized egg was found at Paterson, near the Columbia River. Most vineyards
peripheral to the Yakima Valley are on recently reclaimed desert. The absence of A. epos from
these still relatively barren areas may be explained by the lack of winter hosts.
Mortality.
The percent mortality of immature WGLH and VCLH is given in Table 1; 547 WGLH eggs
produced 152 fifth instars, of which 71 produced 69 adults; 683 VCLH eggs produced 152
fifth instars, of which 84 produced 69 adults. The various factors responsible for mortality
were not evaluated. Some eggs failed to develop and were considered by Cate (1975) to be
infertile. He found that they darkened as they became infected with Aerobacter sp. and Monila
sp. Our observations indicated that most nymphal mortality was associated with molting.
Table 1.
Percent mortality of immature WGLH and VCLH on V. vinifera var.
Grenache at Prosser, Washington, 1985.
Species Egg-instar IV Instar V Total
WGLH 53.2 6.1 56.1
VCLH 778 17.6 81.3
Developmental Rates of E. elegantula and E. ziczac.
Cate (1975) found that WGLH had two and a partial third, or three generations/year at
various locations in California. He reported that development was completed in 844 D° during
the proper limits of daylength (see below) while Jensen and Flaherty (1981) reported 980 D®.
The generations became increasingly asynchronous during the growing season. Females caged
at 21°C (70°F) deposited an average of 1.31 eggs/day for a mean total of 28.2.
WGLH adults entered reproductive diapause when exposed to daylength less than 13.6 h in
late summer. Diapausing females were unmated, and the gonads of both sexes were unde-
veloped. Gonad development resumed when daylength increased to 11.6 h but was very slow
until grape foliage became available. Laboratory studies showed a preoviposition period of
192 D®° at 27°C (80°F) and 246 D®° at 21°C (70°F).
J. ENTOMOL Soc. Brrr. COLUMBIA 86 (1989), SEPT. 30, 1989 31
A WGLH nymph destroyed a mean total of 43.6 mm? leaf surface to maturity at 21°C
(70°F). At this temperature the adult consumed an average of 6.72 mm2/day.
Pepper and Mills (1936) found that VCLH completed one and a partial second generation/
year on Virginia creeper, P. quinquefolia (L.), in Bozeman, Montana. McKenzie and Beirne
(1972) found that non-diapausing adult males were short-lived; two peaks in male density
indicated that the species was bivoltine in British Columbia. Fairbairn (1928) believed at least
three, probably four generations per year occurred on Virginia creeper in Kansas. He observed
the developmental rates of VCLH but made no reference to temperature; the preoviposition
period averaged 5.15 days, the egg stage averaged 8.1 days and nymphal stadia were 3 or 4
days.
MeKenzie and Beirne (1972) found that a VCLH nymph destroyed about one cm? total leaf
surface. Oviposition rates were lower on American varieties of Vitis labrusca than on V.
vinifera and its hybrids. Younger nymphs were seen to be entangled in the leaf hairs of
American grapes.
The mean physiological time between oviposition and imaginal molt for WGLH and VCLH
is given in Table 2. Males of both species became adults before females (pooled ¢ test, P <
0.05), a characteristic common in Cicadellidae (DeLong, 1971).
VCLH developed in less time that WGLH (pooled ¢ test, P < 0.05). The occurrence of
VCLH at higher latitudes than WGLH (Metcalf, 1968; McKenzie and Beirne, 1972) may
partly reflect this.
’
Table 2.
Developmental time, in day-degrees above 10.3°C, of Erythroneura spp.
on V. vinifera var. Grenache at Prosser, Washington, 1985.
n mean D° S
WGLH males 31 398.2 15.0
WGLH females 36 406.3 14.5
WGLH total 67 402.6 15.2
VCLH males 33 386.2 12.6
VCLH females 36 394.4 10.2
VCLH total 69 390.5 11.8
WGLH developmental time was less than half of that reported by Cate (1975) who recorded
development at constant temperatures. Development of an insect may take less physiological
time under fluctuating temperatures (Siddiqui and Barlow, 1973), such as were used here.
Shortened developmental time, perhaps resulting from a lowered developmental threshold,
could be an adaptation to a shorter growing season, but such an extreme difference was
unexpected. Precautions were taken so that cage interiors were not warmer than the surround-
ing air temperature. The average temperatures within the cage and beneath the adjacent leaf
were 11.6 and 11.8°C. The difference was considered insignificant (paired f test, t= 0.15, P<
0.1, 319 df). A repetition of this experiment using WGLH from California and Washington
might eliminate uncertainty in comparing populations.
Competition between Erythroneura spp.
Because WGLH and VCLH feed on V. vinifera in an apparently identical manner, and are
seen on the vine at the same time of year, they may compete for grapevines in southcentral
Washington. If this is the case, the distribution of Erythroneura spp. on grapevines (Fig. 1)
indicates that WGLH is the more successful competitor. Although no experiments were
conducted placing WGLH and VCLH in direct competition, certain observations suggest a
mechanism for WGLH success.
32 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), Sept. 30, 1989
VCLH occurs in vineyards where A. epos is rare or absent. The relative density of arthropod
predator species was not measured but all predators collected on V. vinifera at Prosser, where
only WGLH was found, were also collected at Cold Creek, where both leafhoppers were
found. VCLH was not seen among the tens of thousands of WGLH collected on grapevines at
Prosser, but was easily found on Virginia creeper nearby.
During this study, WGLH and VCLH were raised on caged V. vinifera in a greenhouse.
Cultures were begun by introducing adults from the mixed population of WGLH and VCLH at
Cold Creek. Each inoculum was first sorted in an effort to introduce only one species, but often
included a small percentage of the other species. Eleven cages originally containing a large
majority of WGLH, after several months with no additional input, contained a large majority
of VCLH. The reverse never occurred.
Adults of both Erythroneura spp. escaped occasionally when the cages were opened, and
flew to uncaged V. vinifera in the same greenhouse. These escaped leafhoppers multiplied until
the uncaged vines were heavily damaged. At that time, the leafhoppers on the uncaged vines
were almost exclusively VCLH. No evidence of A. epos was found in the greenhouse.
Competition between WGLH and VCLH in the greenhouse was not carefully controlled,
but the outcome was so striking that we considered VCLH to have held a competitive
advantage. When these observations are considered along with the known distributions of
WGLH, VCLH and A. epos in the field, we concluded that VCLH is kept from grapevines in
most of southcentral Washington by the wasp. Oviposition behavior varies between WGLH
and VCLH. VCLH may lay eggs singly or in clusters, WCLH lays eggs only singly. A cluster
of VCLH eggs may provide a more powerful chemical stimulus than a single egg for a
searching A. epos female.
An Egg-associated Antifeedant.
When grape leaves supporting VCLH became chlorotic from feeding injury, the egg clusters
were found to be surrounded by an undamaged area of leaf tissue. We suspected that the egg
cluster exerted an antifeedant effect. The antifeedant theory was further investigated by
confining nymphs and adults of both leafhoppers, separated by stage and species, on grape
leaves with eggs of either spp. using the clip-on cages described earlier. After each caged leaf
area had turned white with feeding damage it was examined under a dissecting microscope
(20X) for undamaged tissue surrounding any eggs. Nymphs and adults of both spp. did not
feed near the eggs of VCLH, but did feed near the eggs of WGLH. This antifeedant effect,
perhaps chemical in nature, may disperse VCLH nymphs from crowded oviposition sites. If
feeding by Erythroneura spp. can cause egg mortality by desiccation, then VCLH may have a
reduced egg mortality when leafhopper density is high.
No efforts were made to isolate or characterize the anti-feedant, but the possibility exists for
the development of a selective leafhopper control, based on repellency or other characteristics
of an antifeedant.
ACKNOWLEDGMENT
Scientific Paper No. 7848. Project No. 1765. College of Agriculture and Home Economics,
Washington State University, Pullman, WA 99164. This research was supported in part by a
grant from the Washington Wine Advisory Council and is part of a dissertation submitted by J.
D. Wells in partial fulfillment of the M.S. requirement by the Department of Entomology and
the Graduate School of Washington State University. We thank Dr. Paul W. Oman for
confirming the Cicadellid identifications; Drs. K. S. Pike, E. Burts, and W. J. Turner, for
critically reviewing the manuscript; Guy Reisenauer for writing the Fortran computer program
to analyze physiological development time; and to Chateau Ste. Michelle winery employees,
Donna Hirschfelt, Alice Gittings, Joan Johnson and Richard Wheeler.
J. Enromot Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 33
REFERENCES CITED
Beamer, R. H. 1936. Species of Erythroneura of the comes group. Univ. Kans. Sci. Bull. 24:261-307
Beime, B. P. 1956. Leafhoppers (Homoptera: Cicadellidae) of Canada and Alaska. Can. Entomol. Suppl. 2. 180 p.
Cate, J. R. 1975. Ecology of Erythroneura elegantula Osbom in grape ecosystems in California. Unpubl. Ph.D.
Thesis, Univ. Calif. Berkeley. 349 p.
Capizzi, J., G. Fisher, H. Homan, C. Baird, A. Antonelli, and D. Mayer. 1985. Pacific Northwest Insect Control
Handbook. Cooperative Extension of Oregon, Idaho, and Washington. 316 p.
DeBach, P. and C. B. Huffaker. 1971. Experimental techniques for evaluation of the effectiveness of natural
enemies. pp. 113-142 Jn C. B. Huffaker (ed.). Biological Control. Plenum, New York. 511 p.
DeLong, D. M. 1931. The more important species of leafhopper affecting the apple. J. Econ. Entomol.
24:1214-1222.
Doutt, R. L. and J. Nakata. 1973. The Rubus leafhopper and its egg parasitoid: an endemic biotic systsm useful in
grape pest management. Environ. Entomol. 2:381-386.
Essig, E. O. 1926. Insects of Western North America. MacMillan, New York. 1035 p.
Fairbairn, V. M. 1928. The life history of Erythroneura ziczac Walsh (Homoptera, Cicadellidae). J. Kans.
Entomol. Soc. 1:79-84.
Frick, K. E. 1952. The value of some organic phosphate insecticides in control of grape mealybug. J. Econ.
Entomol. 45:340-341.
Gillette, C. P. 1898. American leafhoppers of the subfamily Typhlocybinae. U.S. Nat. Mus. Proc. 20:709-773.
Hitchcock, C. L. and A. Cronquist. 1973. Flora of the Pacific Northwest. Univ. Wash. Press, Seattle. 730 p.
Jensen, F. L. and D. L. Flaherty. 1981. Grape leafhopper, pp. 98-110. Jn D. L. Flaherty, F. L. Jensen, A. N.
Kasimatis, H. Kido, and W. J. Moller (eds.). Grape Pest Management. Div. Agric. Sci. Univ. Calif. Pub.
4105. 312 p.
Knowlton, G. F. 1933. Notes on injurious Utah insects - 1932. Utah Acad. Sci., Arts and Letters Proc. 10:159-162.
Metcalf, Z. P. 1968. General catalogue of the Homoptera. Fasc. 6. Cicadelloidea. Part 17. Cicadellidae. USDA,
ARS. 1513 p.
McKenzie, L. M. and B. P. Beime. 1972. A grape leafhopper, Erythroneura ziczac (Homoptera: Cicadellidae), and
its mymarid (Hymenoptera) egg-parasite in the Okanagan valley, British Columbia. Can. Entomol.
104:1229-1233.
Oman, P. W. 1949. The nearctic leafhoppers (Homoptera: Cicadellidae), a generic classification and checklist.
Entomol. Soc. Wash. Mem. 3. 253 p.
Pepper, J. H. and H. B. Mills. 1936. The Virginia creeper leafhopper. Mont. Agric. Exp. Stn. Bull. 314. 5 p.
Pickett, C. H., L. T. Wilson, D. Gonzalez, and D. L. Flaherty. 1987. Biological control of variegated grape
leafhopper. Calif. Agric. 41:14-16.
Robinson, W. 1926. The genus Erythroneura north of Mexico. Univ. Kans. Sci. Bull. 16:101-155.
Siddiqui, W. H. and C. A. Barlow. 1973. Effects of some constant and alternating temperatures on population
growth of the pea aphid (Homoptera: Aphididae). Can. Entomol. 105:145-156.
Wirtner, P. M. 1904. A preliminary list of the Hemiptera of western Pennsylvania. Ann. Camegie Mus. 3:183-232.
Wolfe, H. R. 1955. Leafhoppers of the state of Washington. Wash. Agric. Exp. Stn. Circ. 277. 37 p.
ERRATA
In the paper entitled ‘‘Semiochemicals...”’ by S.M. Salom & J.A. McLean (Vol. 85:34 - 39,
1988), some typesetting errors appeared on p. 37 under RESULTS. In Experiment 1, line two,
Pkw 0.01 should read P >0.01. On the same line, P 0.05 should read P >0.05. The > sign is also
missing from the same type of statistical presentation in Experiment 2, lines two, three, and
fifteen (last line, p. 38).
34 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
EFFECT OF HOST PHENOLOGY ON OVIPOSITIONAL PREFERENCE OF
WINTER FORM PEAR PSYLLA (HOMOPTERA: PSYLLIDAE)
L.C. STUART, B.A. Butr!, AND R.L. BELL
U.S. DEPARTMENT OF AGRICULTURE
AGRICULTURAL RESEARCH SERVICE
APPALACHIAN FRUIT RESEARCH STATION
45 WILTSHIRE ROAD
KEARNEYSVILLE, WV 25430
ABSTRACT
In free-choice assays using budwood at similar stages of leaf emergence, winter form
(WF) pear psylla (Cacopsylla pyricola Foerster form simulans) showed no oviposi-
tional preference for psylla-susceptible ‘Bartlett’ (Pyrus communis L.) over psylla-
resistant W6 (P. ussuriensis Maxim.) or NY10353 (P. ussuriensis x P. communis
hybrid). After budbreak, WF psylla oviposited on the host with foliage in the most
advanced stage of leaf emergence.
Key Words: Cacopsylla pyricola Foerster, pear psylla, ovipositional cues, host plant
resistance, behavior.
The pear psylla, Cacopsylla pyricola Foerster, exists in two distinct seasonal forms: form
typica, or summer form, (SF) and form simulans, or winter form (WF). The WF psylla
overwinter as adults in reproductive diapause, frequently outside the orchards (Burts, 1970;
Fye, 1983). Oviposition begins on the reproductive host, pear (Pyrus communis L.), early in
the spring in response to increasing daylength (McMullen and Jong, 1976). Release from
diapause is coincident with tree phenology, beginning shortly before budbreak (Burts, 1970).
Host plant location is an essential step in the repopulation of orchards.
Psylla-resistant genotypes of Pyrus ussuriensis Maxim. (Westigard et al., 1970) and P.
ussuriensis x P. communis hybrid origin (Harris, 1973) have been identified in which
Ovipositional non-preference by SF is an important modality of host resistance. Harris (1973)
also reported that differences in ovipositional preference exhibited by WF psylla between
resistant and susceptible hosts were small, and suggested that differences in phenology may be
involved. Vegetative budbreak and bloom of trees of this genetic lineage is three to ten days
earlier than that on P. communis cultivars, which, as a group, are susceptible to the pear psylla.
Oviposition by WF increases in response to budbreak and foliar expansion (Smith, 1965). On
Asian, domesticated European, and local landrace cultivars of apple and pear, a European pear
psyllid, Cacopsylla pyri L., and an apple psyllid, Psylla melanoneura Foerster form taurica,
Oviposited first on the genotypes which came out of dormancy earliest (Lazarev, 1974).
In these field studies, differences in host phenology were confounded with genotype,
particularly when different host species were involved. Because terminal buds can influence
the emergence of buds basal to them, a preliminary experiment was conducted to investigate
this matter of technique. A subsequent experiment was then designed to investigate the
contribution of host phenology to ovipositional performance by WF pear psylla through the
early stages of leaf emergence.
MATERIALS AND METHODS
Experiment I. We tested the hypothesis that WF would oviposit preferentially on dormant
budwood of a psylla-susceptible P. communis cultivar, ‘Bartlett’, over a resistant wild-type
clone, P. ussuriensis W6 (W6) (Westigard et al., 1970). The experiment was designed as a free-
choice paired comparison. Dormant budwood was collected from the Appalachian Fruit
Research Station, Kearneysville, WV, orchard on 14 March 1985. Presence of a terminal bud
may delay the opening of lateral buds and thereby influence psylla preference. Therefore, we
used ten matched pairs of ‘Bartlett’ and W6 budsticks, five pairs with and five pairs without
terminal buds. All budsticks had three lateral buds. The budsticks were placed in individual
vials of water. Each pair (‘Bartlett’ and W6) was placed in a cylindrical plastic cage with four
1 Present address: International Atomic Energy Agency, Insect and Pest Control Section, Wagramerstrasse 5, P.O.
Box 200, A-1400, Vienna, AUSTRIA
J. ENroMo. Soc. BRIT. COLUMBIA 86 (1989), SEPT. 30, 1989 35
male and four female adult WF which had been field-collected the same day. Cages in this and
subsequent experiments were placed in a rearing room at 25C, with a photoperiod of 16:8
(L:D). Egg counts were made on day six after insect removal. Data were analyzed using paired
2-tailed t-tests.
Experiment II. This experiment was designed as a set of six dual-choice comparisons:
three between susceptible and resistant hosts at the same stages of bud development; two
between stages that would occur naturally with the resistant host further developed than the
susceptible host; and one between the resistant host in dormant condition and the susceptible
host at budbreak, a situation not occurring naturally. The final comparison was made to ensure
that choice was based on bud development and not host genotype.
The susceptible host was ‘Bartlett’ and the resistant was NY10353 (NY), a P. ussuriensis x
P. communis hybrid shown to be resistant by greenhouse and field counts of nymphs (R.L.Bell,
unpublished data; R.C. Lamb, personal communication). Budbreak of NY occurs about 5-7
days earlier than ‘Bartlett’ in the field. Fully-dormant budwood was collected from the orchard
in mid-February 1987, and held in storage at 2C. Because budbreak proceeds more rapidly on
NY than on ‘Bartlett’, bud stages were matched by removing ‘Bartlett’ budsticks from cold
storage in advance of NY. Terminals buds were removed, because budbreak of lateral buds was
observed to occur more uniformly in their absence. Adult WF were collected from the field by
beating tray and aspirator on 14 April 1987, held in a refrigerator at 3C overnight and
introduced to budsticks the following day.
Each choice test was replicated 10 times and consisted of a ‘Bartlett’ and a NY budstick,
each with five buds. Budsticks were placed in individual vials of water, and each pair was
enclosed in a plastic cylindrical cage with two male and two female WF. Eggs were counted
after day five in the first five comparisons. In the final comparison, ‘Bartlett’ at budbreak vs.
dormant NY, eggs were counted after three days to avoid the loss of uniform bud development,
which had begun on about day three in previous comparisons. Square root transformation
failed to improve normality and equality of variances in all comparisons, and, therefore,
untransformed data were analyzed by paired 2-tailed t-tests.
Although we attempted to match each pair of budsticks as closely as possible in both size
and the condition of the five buds, this uniformity could not be maintained. Within the five-day
test period, leaf emergence progressed rapidly. Buds which had begun dormant had reached
green tip, and buds which were initially at budbreak and green tip were at varying stages of leaf
emergence and expansion, with NY buds developing faster than ‘Bartlett’ buds in most cases.
Therefore, the data was also separated into three categories according to the relative stage of
leaf emergence at the end of the experiment: NY equal to ‘Bartlett’, NY more advanced than
‘Bartlett’, and ‘Bartlett’? more advanced than NY.
RESULTS AND DISCUSSION
Experiment I. W6 buds, particularly the terminals, developed faster than ‘Bartlett’ buds.
On intact budsticks, more eggs were oviposited on W6 terminal buds, which had ca. 1 cm of
foliage, than on the lateral buds (Table 1; Prob. > /t/ = 0.07). More eggs were found on the most
distal lateral buds. There was no significant difference between lateral and terminal buds of
‘Bartlett’ (Prob. > /t/ = 0.77). Eggs were deposited on the foliage or on tops of adjoining bud
scales. On dormant buds, eggs were found on and around bud scales and in cracks near buds.
The data shown for mean number of eggs on lateral buds represents the total eggs on all three
lateral buds of each budstick. In no case were more eggs found on a single lateral bud than on
the terminal.
36 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
Table 1.
Mean number of eggs + standard error oviposited by winter form pear psylla on ‘Bartlett’ and
Pyrus ussuriensis W6 (W6) budsticks with and without terminal buds.”
Budsticks with terminal buds Budsticks without
Host 3 Lateral buds Terminal buds Total terminal buds Overall
Bartlett 56.2+13.2 530+13.9 109.2+249 7944262 943+431.5
W6 418+108 1396+38.2 181.4+40.3 19824494 189.8 + 91.1
Difference 14.4 + 7.5 -86.6 + 36.5 -72.2+29.7 -118.8+ 54.4 -95.5 + 30.2
(Bartlett-W6)
Prob. >/t/2/ 13 .08 07 09 .02
1/ Two six-day free-choice tests, five replications each.
2/ Null hypothesis, (H,): ‘Bartlett’-W6 = 0 at p = 0.05, 2-tailed paired t-test.
Where terminals were removed, W6 buds all opened rapidly. By day six, they showed ca.
2.5 cm of foliage, and new leaves were beginning to separate and expand, while ‘Bartlett’ buds
were only slightly swollen with no foliar tissue showing. Slightly more eggs were deposited on
W6, either directly on foliar tissue or on nearby bud scales, than on the still- dormant ‘Bartlett’
(prob. > /t/ = 0.09). However, one ‘Bartlett’ budstick developed faster than its paired W6 and
showed foliage at all nodes. The 168 eggs deposited on that single budstick accounted for 42%
of all eggs found on ‘Bartlett’. The corresponding W6 had 113 eggs. There were no significant
differences in oviposition between budsticks with or without terminals (Prob. > /t/ = 0.49).
Therefore, the data were combined to test for preference between hosts.
WF did not prefer the budwood of the susceptible cultivar ‘Bartlett’ for oviposition. Instead,
they chose oviposition sites on buds where foliage appeared, even if this was on the
moderately-resistant W6. This could be interpreted to mean that W6 was more attractive for
oviposition. However, the one replication in which eggs were concentrated on a ‘Bartlett’
budstick which was further advanced also leads to the hypothesis that attraction to foliage as an
Oviposition site was more important than other genotypic factors to WF psylla.
Experiment II. Ovipsition occurred on budwood of all stages, but was least when buds
were dormant at the beginning of the assay (Table 2). Oviposition on both genotypes increased
dramatically between the dormant stage and budbreak, and increased again, up to 3-fold
between budbreak and green tip. In the 3-day test which began with dormant NY vs. ‘Bartlett’
at budbreak, only a single egg was found on NY.
Table 2.
Mean numbers of eggs deposited by winter form pear psylla on ‘Bartlett’ and NY10353
budsticks.!/
__Bud stage?/ _ Mean number of eggs/budstick + se
Bartlett NY10353 Bartlett NY10353 Difference Prob. > 1t4/
D D 95+ 3.9 3.7.4: 1:6 5.8 + 3.1 .094
BB BB 1O2 215% 77.9 + 19.9 -1.7 + 28.9 954
GT GT 113.7 + 29.8 210.5 + 38.0 -96.8 + 56.8 123
D BB 50.5 + 19.0 62.2 + 19.9 -11.7 + 29.1 .697
BB GT 41.2 + 10.0 184.0 + 29.0 -142.8 + 32.9 .002
BB?/—s—:D3/ 17.8 + 6.5 0.1+0.1 17.1. £:6:5 .024
1/ In five-day free-choice test with 10 replications, analyzed by bud stage on day 0.
2/ D = dormant, BB = budbreak, GT = 1/4” green tip.
3/ Three-day test.
4/ Null hypothesis (H,): ‘Bartlett? = NY10353; 2-tailed t-test.
J. ENTOMOL Soc. BRIT. COLUMBIA 86 (1989), SEPT. 30, 1989 37
When the data were analyzed on the basis of stage of emergence at the end of the
experiment, the largest numbers of eggs were found on the host which had the most exposed
foliar tissue (Table 3). No significant differences were found between NY 10353 and ‘Bartlett’
where their buds had emerged to the same stage.
Adult pear psylla (WF and SF) show no preference for resistant or susceptible cultivars in
either frequency or duration of visitation when foliar conditions are approximately equal
(Harris, 1973; 1975). Our study indicated that, in addition, WF showed no ovipositional
preference among phenologically similar hosts, from dormancy through early stages of leaf
expansion. Instead, WF females were attracted to buds in the most advanced stage of foliar
development. Similar observations of other psyllid species on pome fruit (Lazarev, 1974) tend
to support the hypothesis that lack of host discrimination early in the season may be a
widespread occurrence in psyllids.
Summer form pear psylla have shown ovipositional preferences among host genotypes with
fully expanded leaves (Westigard et al., 1970; Harris, 1973; Harris, 1975). This observation is
also true when comparing orchard-grown trees of ‘Bartlett’ and NY (R.L. Bell, unpublished
data). SF psylla will oviposit on dormant buds of ‘Bartlett’ (in laboratory) at a low frequency,
and, hence, are behaviorally similar in this respect to WF psylla (Butt and Stuart, 1986).
Our data are consistent with observations that oviposition by WF females increases after
budbreak (Smith, 1965). The cue(s) triggering host preference for oviposition may appear or
Table 3.
Mean number of eggs deposited by winter form pear psylla on ‘Bartlett’ (Bart) and NY 10353
(NY) budsticks, analyzed by initial and final bud stage.!/
Final bud stage
Initial NY = Bart NY > Bart Bart > NY
Bud stage?/ )
Bat NY N _ Bart NY N__ Bart NY N__ Bart NY
D D 10 9.5 3 0 - - 0 . -
BB BB 8 82.3 73.9 2 52.0 94.0 0 - -
GT?/ GT3/ 3 186.0 158.3 6 91.7 225.3 0 - -
D*/ BB*4/ 2 38.0 30.0 4 10.3 107.5 3 1283 42.0
BB GT 0 - - 10 41.2 184.0 0 - -
BBY D* 0 - - 0 - - 10 17.8 0.1
Final bud
stage mean 23 60.3 50.6 22 50.3. 2173;2. -.13 43.3 9.7
Mean
difference®/ + se 9.7+ 12.4 e122 907% 271 33.6 + 10.9
Prob.> /t/ .4406 0.0002 0.0098
1/ In five-day free-choice test, 10 replications per initial bud stage.
2/ D = dormant, BB = budbreak, GT = 1/4” green tip.
3/ One replication dropped due to death of one budstick.
4/ One replication dropped due to death of female psylla.
5/ Three-day test.
6/ Bartlett-NY.
38 J. ENTOMOL Soc. BRiT. COLUMBIA 86 (1989), SEPT. 30, 1989
be stronger when foliage develops, because the degree of oviposition is positively associated
with the amount of foliar tissue available. The exact basis of this behavior is uncertain,
considering the ovipositional preferences exhibited by SF psylla. The WF female psylla may
not be capable of discriminating between host genotypes on the basis of the cues affecting SF
females. Alternatively, if only fully expanded leaves express these cues, WF do not have the
opportunity to discriminate among hosts because of phenological differences.
ACKNOWLEDGMENTS
The authors would like to acknowledge the assistance of Dr. Mark W. Brown with the
statistical analyses and critical review of this manuscript. Dr. R.C. Lamb of Cornell University
kindly provided NY 10353, and P. ussuriensis W6 was obtained from Dr. M.N. Westwood of
Oregon State University.
LITERATURE CITED
Burts, E.C. 1970. The pear psylla in central Washington. Wash. Agric. Exp. Stn. Cir. 516. 13 pp.
Butt, B.A. and C. Stuart. 1986. Oviposition by summer and winter forms of pear psylla (Homoptera: Psyllidae) on
dormant pear budwood. Environ. Entomol. 15:1109-1110.
Fye, R.E. 1983. Dispersal and winter survival of the pear psylla. J. Econ. Entomol. 76(2):311,315.
Harris, M.K. 1973. Host resistance to the pear psylla in a Pyrus communis x P. ussuriensis hybrid. Environ.
Entomol. 2(5):883-887.
Harris, M.K. 1975. Greenhouse testing of pears with Pyrus ussuriensis lineage for resistance to Pyslla pyricola. J.
Econ. Entomol. 68(5):641-644.
Lazarev, M.A. 1974. Trophic selectivity of apple and pear psyllas. Byull. Gos. Nikitsk. Bot. Sada 2(1):44-47 (in
Russian).
McMullen, R.D. and C. Jong. 1976. Influence of temperature and host vigor on fecundity of the pear psylla
(Homoptera: Psyllidae). Can. Ent. 104:1209-1212.
Smith, E.H. 1965. The susceptibility of life history stages of pear psylla to oil treatment. J. Econ. Entomol.
58:456-464.
Westigard, P.H., M.N. Westwood and P.B. Lombard. 1970. Host preference and resistance of Pyrus species to the
pear psylla, Psylla pyricola Foerster. J. Amer. Soc. Hort. Sci. 95(1):34-36.
J. Enromo Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 39
MORPHOLOGY, LIFE HISTORY AND IDENTIFICATION OF SEX
PHEROMONE COMPONENTS OF AN UNDESCRIBED SPECIES OF
CHORISTONEURA (LEPIDOPTERA: TORTRICIDAE) ON SCOTS PINE IN
BRITISH COLUMBIA
T.G. GRAY
FoRESTRY CANADA
PACIFIC AND YUKON REGION
PACIFIC FORESTRY CENTRE
506 WEsT BURNSIDE Roap,
VicroriA, B.C. V8Z 1M5
K.N. SLESSOR
DEPARTMENT OF CHEMISTRY
SIMON FRASER UNIVERSITY
BuRNABY, B.C. VS5A 1S6
ABSTRACT
The morphology and life history of a probable new species of tortricid on Scots pine
in British Columbia is described. It differs from other Canadian pine feeding Cho-
ristoneura. Abdominal tip extracts of unmated females contained Z-11- and E-11-
tetradecenyl acetates and alcohols. An equal mixture of these materials was an effective
attractant for capturing males in delta traps and is recommended for the detection and
monitoring of this insect.
INTRODUCTION
The conifer-feeding Choristoneura in North America are composed of three complexes or
series (Powell 1980): (1) the Fumiferana complex, associated with Picea spp. and Abies spp.,
(2) the Lambertiana complex, generally feeding on Pinus spp. and (3) the Carnana complex
which feed on Pseudotsugata spp. Harvey (1985) contends that there are only two groups, one
associated with spruces, Douglas-fir (Pseudotsuga menziesii Mirb. Franco) and true firs
(Abietoideae) and the other feeding on pines (Pinoideae). He includes the Carnana group in the
Fumiferana group. The species described in this paper would, by Powell’s classification, be
included in the Lambertiana complex. In western North America this complex consists of three
subspecies: Choristoneura lambertiana lambertiana (Busck) in northern California and
southern Oregon, C. /. subretiniana Obraztsov in eastern California and C. |. ponderosana
Obraztsov in Colorado, Wyoming and North Dakota. In addition, there are populations in
Wyoming, Montana, Idaho, southeast British Columbia (Silver and Ross 1964) and Oregon
which are intermediate between the three subspecies and vary in a clinal fashion across the
range (Powell 1980). In eastern North America another species, Choristoneura pinus pinus
Freeman, occurs, with a subspecies C. p. maritima indicated in the southern part of its range.
No pine-feeding species has been previously identified in southwestern British Columbia or
Washington State.
The sex pheromone for C. pinus pinus was identified in 1985, (Silk et al. 1985) and found to
consist of E-11- and Z-11-tetradecenyl acetate (85:15) and E-11- and Z-11-tetradecen-1-ol
(85:15); the acetate and alcohol components occurred at a ratio of 9:1. The isolation and
identification of the sex pheromone components of C. lambertiana (Busck) remain to be
investigated, although good attraction occurs in traps using either a blend attractive to C. orae
(Gray et al. 1984) or to the attractive blend proposed for Choristoneura n. sp. described in this
paper.
In June 1979, T.G.G. noticed Choristoneura larvae feeding on Scots pine (Pinus sylvestris
L.) and assumed from their general appearance that they were C. occidentalis, although this
species is not commonly found on pine. Therefore, to confirm this assumption, six delta traps
baited with C. occidentalis pheromone were set out on 23 July and collected on 18 September
1979. There were no Choristoneura adults present in any of the traps.
40
J. ENTomMoL Soc. Brit. COLUMBIA 86 (1989), Sept. 30, 1989
The biology of some of the C. lambertiana subspecies has been described by McGregor
(1968, 1970), Stevens et al. (1977), and Stark and Borden (1965). This paper is based on
observations made from 1979 to 1982 on the biology and life history of a previously
undescribed species on naturally infested Scots pine trees near George Massey Tunnel,
Richmond, B.C., on laboratory rearings with pine cuttings, and on synthetic diet (Robertson
1979). The isolation and identification of the pheromone components used to monitor the
populations are also discussed.
Egg
Larva
Pupa
Adult
First instar:
Second instar:
Third instar:
Fourth instar:
Fifth instar:
MORPHOLOGY
Convex and ovate, 1.13 mm long x 0.6 mm wide, light green,
darkening as eclosion approaches; laid in overlapping, shingle-
like rows on the needles.
pale yellow with light reddish brown head, thoracic shield lighter
than head, 2.07 mm long x 0.33 mm wide.
yellow with dark brown head, thoracic shield brown but lighter
than head, anal plate same color as thoracic shield, 2.00 mm long
x 0.33 mm wide.
creamy-brown with two rows of whitish dots visible with x10
magnification, dark brown head and thoracic shield, the latter with
a white median line; thoracic legs same color as shield; light
brown anal plate. 3.33 mm long x 0.50 mm wide. |
light brown; dorsum with two rows of paired whitish spots with
black centers around setae; gonads visible in males; head dark
brown, thoracic shield black with white leading edge; thoracic
claws black; clypeus and antennae basal segments whitish, anten-
nae black. 4.33 mm long x 0.66 mm wide.
reddish brown with lighter sides, dorsum with two rows of paired
yellowish spots, male gonads visible in third abdominal segment;
head red brown; thoracic shield darker than head. 22.5 mm long x
2.25 mm wide.
Appendages light brown; thoracic segments reddish brown;
abdominal segments light brown and finely textured; interseg-
mental regions reddish brown with coarser texturing; eight cre-
mastal setae, two on each side and four on basal segment; exuviae
pink. Males 11.0 to 12.5 mm, females 13.0 to 13.5 mm in length.
This Choristoneura species resembles the coastal form of C.
occidentalis (Dr. A. Mutuura, Biosystematics Research Centre,
Ottawa, ON, personal communication). The head and thorax are
grey-brown to reddish brown; the hind wings are darker grey than
those of C.lambertiana (Busck); forewings are a grey ground
color with brown to brownish orange ‘markings and numerous
black strigulae; abdomen grey; aedeagus lacks spicules unlike C.
pinus which displays many spicules (Dang 1985); Voucher speci-
mens are available for study from the Canadian National Collec-
tion, Biosystematics Research Centre, Ottawa, ON K1A 0C6 and
from the Regional Collection, Pacific Forestry Centre, Victoria,
B.C. V8Z 1M5 wingspread: males 17 to 19 mm, females 20 to 22
mm.
41
J. ENToMoL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
°
D
Egg masses
larva,
.
.
B.Ce A
ird instar
F. Adult
?
?
hmond
1c
R
ilk enclosure of th
r, mature larva
ine at
.S
insta
C
?
on Scots p
larva
Fifth
oh
instar
E
f second
fourth instar larva,
ing site oO
f
ite O
Feeding s
the development of Choristoneura n.
dles, B. Feed
in
on pine nee
Stages
Eig.-3.
42 J. ENTOMOL Soc. Brir. CoLUMBIA 86 (1989), SEPT. 30, 1989
LIFE HISTORY
Clusters of eggs (Fig. 3A) were laid in a shingle-like fashion during the last week of July and
the first week of August (Fig. 4) distally and on the top surface of pine needles, similar to other
pine-feeding Choristoneura. In 1981, 32 egg masses were collected; of these 90% had two
rows (mean number of eggs per mass was 23.5) and 10% had three rows (mean number of eggs
per mass was 42.0). Field-collected egg masses hatched within 4 to 7 days at 20°C + 2°C. The
eggs slowly darkened and the black head capsules became visible through the chorions 48 h
before eclosion.
The first instar larvae emerged from the eggs and dispersed to seek protected areas to spin
overwintering hibernacula, often within the current year’s pupal webbing on old foliage or old
bud scales. They molted from first to second instar in the autumn and overwintered in the
second instar. In 1982, 20 branches were cut from Scots pine and divided into three sections of
current year’s foliage, old foliage and bare twigs to determine the distribution of hibernacula.
The sections were treated with hot NaOH solution, washed, filtered, and the larvae were
counted (Miller et al. 1971). A total of 35 larvae were recovered of which 85% were found on
the old foliage and bare branches. Even though two egg masses were found on the current
foliage of two branches, only 12 larvae were recovered, indicating that larvae probably moved
away from the light towards the bole of the tree to select an overwintering site. Terrell (1959)
compared stem and branch samples for spruce budworm larvae on Douglas-fir and found, for
an equivalent area, 2.9 larvae on the branches and 58 larvae on the bole.
In spring of 1981, young larvae first appeared on the tips of candles during the last week of
May. Silk threads were visible between tips of needles, around candles and female cones (Fig.
3B) suggesting that larvae dispersed at this time. Larvae had spun silk enclosures at
approximately 45° from the candle’s main stem (Fig. 3C), but attached to it, about 25 mm from
the tip. Feeding started at the base of needle sheaths of new growth. There was no evidence of
needle mining, probably because the new needles were available when larvae emerged from
their hibernacula. In 1982 larvae had spun silk enclosures by the second week of June and
when feeding, only the top 1/4 to 1/3 of their bodies were exposed. Larvae fed with their heads
outward and quickly retracted into their enclosures when disturbed.
Larvae feeding in the field molted from second to third and fourth instar and continued to
feed at the needle bases (Fig. 3D). Those reared in the laboratory on artificial diet (Robertson
1979) stopped feeding at the end of the third instar and entered a second diapause (97%), even
though rearing conditions simulated field conditions. Harvey (1967) similarly noted that C.
EGGS
a
ist INSTAR
oe
2nd INSTAR OVERWINTERING
2nd INSTAR
OVERWINTERING
2nd INSTAR
=|
3rd INSTAR
|---|
4th INSTAR
$= |
5th INSTAR
>|
PUPAE |
ADULTS
|/-~—————++|
i fe a i ee ee
JANUARY APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER
TO 19
MARCH DECEMBER
Fig. 4. Life cycle of Choristoneura n. sp. determined from field observations at Richmond, B.C.
J. EnromMo. Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 43
orae, which we consider to be closely related to Choristoneura n. sp., tended to enter a second
diapause (2%) when reared in the laboratory. When entering the second diapause, third instar
larvae spun tight double silk enclosures and. once enclosed, shed the head capsule and
integument at opposing ends of the hibernaculum. The larva reduced in size from 3.3 - 4.0 mm
to 1.67 - 2.67 mm in length because they ceased feeding and used their food reserves to spin the
hibernacula. There was no visible movement by the larvae unless subjected to high-intensity
light or probing.
Fourth-instar larvae fed mostly on the south facing side of the host. Larvae did not attack the
main stem or developing female cones but usually consumed one needle completely before
chewing another. This behavior is unique to this species. Other Choristoneura species are
wasteful feeders and often take one or two bites from a needle before moving to another; they
thus cause very noticeable defoliation. Feeding sites had an average of 18 needles held to the
developing candle with silk. Defoliation was therefore not detectable from a distance. Most
larvae were in the fourth instar by the third week of June; there appeared to be more larvae
present at that time than when observed as third instars, suggesting a second diapause in the
field.
Fifth-instar larvae looked like those of C. occidentalis. They were more free roaming than
previous instars (Fig. 3E), and they spun loose silk enclosures to secure developing side
candles to the main candle.
Individual pupae were present on the foliage by the first week of July and were attached near
the tips of candles by silk and dead needles. Often, pupae were found under curled immature
cones. They were always oriented with the anterior end pointing distally along the axis of the
candle. The pupal stage in the laboratory averaged 15 days at 19°C and the male/female ratio
was close to 1.
The adults (Fig. 3F) were first evident in mid-July and were visible resting or laying eggs on
the current year’s foliage for approximately four weeks. The adults, which normally fly at
dusk, flew only during daylight hours when branches were disturbed by the wind or physically
moved.
WHITE PINE
WESTERN LARCH
WESTERN HEMLOCK
INTERIOR D - FIR
SCOTS PINE
WHITE SPRUCE
COASTAL D - FIR
LODGEPOLE PINE
0 20 40 60 80
PERCENT SURVIVAL TO PUPAL STAGE
Fig. 1 Survival of Choristoneura n. sp. on different hosts maintained in an environmental chamber for
36 days. n=80
44 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
Host
Scots pine, Pinus sylvestris L. Laboratory rearings indicate that this insect can survive
equally well on lodgepole pine (Pinus contorta Dougl.), coastal Douglas-fir and white spruce
(Picea glauca (Moench) Voss), but it has not been found on these native species (Fig. 1). Scots
pine is a non-native tree. These were planted by the Ministry of Transportation and Highways
in 1959 as 18-inch seedlings. Increment cores taken in 1980 indicated that the trees were 21
years old.
Distribution
Living specimens occurred in Richmond, British Columbia. Pheromone trapping with equal
amounts of the two acetates and two alcohols failed to catch any Choristoneura sp. on Scots
pine in Norway, (Dr. A. Bakke, Norsk Institutt For Skogforskning, Postboks 61, Norway,
personal communication). Similarly, traps baited with this blend failed to trap any Cho-
ristoneura sp. in Japan, (Dr. S. Suzuki, Hokkaido Forest Experiment Station, Hokkaido, Japan,
personal communication). Monitoring with pheromone traps traced the origin of the Scots pine
to a Richmond nursery (Fig. 2) which had imported the trees in the early 1950s, probably from
Ontario or Washington State. This was confirmed by talking to the nursery owners but the
trees’ origin could not be verified due to the length of time that had lapsed.
' VANCOUVER EE
(12) AVERAGE NUMBER OF
\
\
OR
N
x
\
MOTHS PER TRAP
0 3 km
Seed
LULU
ISLAND
(12) SURREY
LZ lo) RICHMOND
SEZ ©)
CENTRE ~<._ &
BOUNDARY BAY ROCK
Fig. 2. Distribution of Choristoneura n. sp. around the location where it was first discovered at the George
Massey Tunnel, Richmond, B.C.
Associated Insects
No parasitoids were encountered during this insect’s life cycle, either in the 35 egg masses,
or in more than 100 fourth- and fifth-instar larvae collected and reared. The most common
lepidopteran present on the host trees was the European pine shoot moth, Rhyacionia buoliana
(Schiffermiiller), and in 1980 six out of ten new candles contained a shoot moth larva. The
oblique-banded leaf roller, Choristoneura rosaceana (Harris), was also present in limited
numbers, as was Ditula (Batodes) angustiorana (Haworth); both of these species are known to
be polyphagous feeders. Silverspotted tiger moth larvae, Lophocampa argentata (Packard),
were observed feeding on old foliage of several trees.
J. ENromo_ Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 45
IDENTIFICATION OF PHEROMONE COMPONENTS
Methods
Late instar larvae were hand picked and reared to pupation on clipped branches in moist
sand in a propagation box in a greenhouse at about 20°C. The pupae were sexed, separated and
placed in petri dishes with moist filter paper. The female pupae were kept under a 16:8 L:D
photoperiod and maintained at that regime after eclosion.
Abdominal tips were excised from unmated females 2 to 4 days old at 1 to 3 hours into the
scotophase (Gray et al. 1984). Each tip was washed with 5 ul of redistilled hexane and the
wash was injected into a Hewlett-Packard 5880A capillary gas chromatograph (CGC) in
splitless mode, equipped with a flame ionization detector. The capillary column was 0.25 mm
id. x 30 m methyl silicone (SE-30) (Hewlett-Packard Co., Palo Alto, CA), programmed at
80°C for 2 min, warming at 15°C/min to 180°C and isothermal at 180°C. Injector and detector
temperatures were 275°C. Standards were run under identical conditions to enable the
comparison of retention times.
A pooled sample of washes from five females was analyzed on a Hewlett-Packard 5985
capillary gas chromatograph/mass spectrometer (GC/MS) in the splitless mode. The 0.32 mm
id. x 15 m SE-30 column (JJ & W Scientific, Folsom, CA) was programmed at 70°C for 1 min,
warmed at 4°C/min to 210°C and isothermal at 210°C.
Field testing of candidate components was conducted in 1980 on Scots pine using delta traps
(made from 2-L milk cartons) coated inside with Bird Tanglefoot (The Tanglefoot Co., Grand
Rapids, MI 49504). The traps, with a trapping surface of 495 cm2, were baited with candidate
chemicals in polyvinylchloride (PVC) 5% w/w (Daterman 1974) which were impaled with a
pin inside the delta traps. The lures were PVC rods 3 mm in diameter and 5 mm in length
containing 1250 ug of the candidate chemical; they were aged for 5 days at 20°C prior to use to
stabilize the release rate. The chemical lures were replicated four times while unmated females
of C. pinus pinus and C. n. sp. were replicated twice.
Results and Discussion
Capillary gas chromatographs of individual tip washes indicated four pheromone com-
pounds. No aldehyde component was detected, indicating that the species was more closely
related to C. orae and the pine feeding Choristoneura, which lack an aldehyde component in
their attractive blends (Gray et al. 1984; Harvey 1985; Silk et al. 1985). The four detected
compounds had retention times coincident with E-11-tetradecen-1-ol (E-11-14:0H), Z-11-
tetradecen-1-ol (Z-11-14:0H) (E/Z~ 2:1), E-11-tétradecenyl acetate (E-11-14:Ac) and Z-11-
tetradecenyl acetate (Z-11-14:Ac) (E/Z~ 2.5:1). There was no indication of any saturated
alcohols or acetates present in the single insect traces. Capillary GC/MS indicated identical
retention times and fragmentation patterns for the four detected compounds and synthetic
standards.
Field bioassays conducted in 1980 (Table 1) indicated that an equal mixture of
E/Z-11-14:Ac and E/Z-11-14:0H was a better attractant than the individual compounds,
although the means were not significantly different with the exception of the poor response to
Z-11-14:Ac. Additional testing in 1981 (Table 2) again indicated that an equal mixture of
E/Z-11-14:Ac and E/Z-11-14:0H was the most attractive blend and was able to attract more
moths than did unmated females. The ability of unmated female C. pinus pinus to attract a
considerable number of male C. n. sp. (Table 2) would suggest a taxonomic closeness, at least
chemically if not morphologically (Dang 1985). An initial test in 1979 using a similar
chemical blend as that proposed for Choristoneura occidentalis (Cory et al. 1982) containing
E/Z-11-tetradecenals failed to attract any male Choristoneura. We therefore recommend as an
effective sex attractant lure for detection and monitoring Choristoneura n. sp. E/Z-11-
tetradecenyl acetates and E/Z-11-tetradecen-1-ols in equal amounts and a lure loading of 312
ug of each chemical.
CONCLUSIONS
This undescribed insect may be considered by some authorities as being a hybrid, or a host
race, “‘a noninterbreeding sympatric population, which differs in biology but not, or scarcely,
46 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
Table 1. Number of Choristoneura n. sp. captured from 23 to 27 July 1980 at
Richmond, B.C.
Lure Composition Males Average/
% caught night/trap
E/Z-11-14:Ac+
E/Z-11-14:0H 25/25/25/25 54 3.38 a
Z-11-14:0H 100 38 2.38 a
E-11-14:Ac 100 37 Z.ala
E-11-14:0H 100 24 1.50 a
Z-11-14:Ac 100
Treatment totals followed by the same letter are not significantly different, Duncan’s
new multiple range test, p <0.05.
Table 2. Number of males captured from 16 to 31 July 1981 at Richmond, B.C. when
testing unmated females and synergism of isolated pheromone-like
compounds.
Composition Average/
% night/trap
E/Z-11-14:Ac+ 25/ 25/25/25
E/Z-11-14:0H
E/Z-1i-14:Ac+ 33/33/33
E-11-14:0H
E/Z-11-14:Ac 80/20
E/Z-11-14:Ac+ 33/33/33
Z-11-14:0H
E-11-14:Ac+ 33/33/33
E/Z-11-14:0H
E-11-14:Ac 100
Z-11-14:Ac+ 33/33/33
E/Z-11-14:0H
Z-11-14:Ac 100
subtotal
© Choristoneura n.sp.
Choristoneura pinus pinus
Total
Treatment totals followed by the same letter are not significantly different. Duncan’s
new multiple range test, p <0.05.
J. Enromov Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 47
in morphology ... (and which are) prevented from interbreeding by preferences for different
food plants or other hosts” (Mayr et al. 1953).
We believe that this insect is in fact a distinct species for several reasons: it possesses a
unique pheromone, and is thus reproductively isolated; the ovipositing females display a
distinct host preference, in this case Scots pine; the geographic distribution of the population,
the ability of larvae to feed on Scots pine; and the feeding behavior of larvae, all these appear
to be unique within this genus.
The origin of this species is unknown. The restricted distribution, proximity to international
marine import terminals, exotic host, and the lack of parasites suggest that it may be an
introduced species. However, taxonomically it appears closely related to C. orae and C. pinus
pinus, both of which are Canadian species.
ACKNOWLEDGEMENTS
We thank Misses Tammy Hubscher and Nancy Morris for their technical assistance. We also
thank the Ministry of Transportation and Highways for granting permission to conduct this
study on their restricted property and the Natural Sciences and Engineering Research Council
of Canada for financial support (A3785 and G1039). We thank Drs. C. Preston, L. Humble and
H. Moeck for reviewing the manuscript and Mr. John Wiens for the illustrations.
REFERENCES
Cory, H.T., G.E. Daterman, G.D. Daves, Jr., L.L. Sower, R.F. Shepherd and C.J. Sanders. 1982. Chemistry and
field evaluation of the sex pheromone of the western spruce budworm. J. Chem. Ecol. 8: 339-350.
Dang, P.T. 1985. Key to adult males of conifer-feeding species of Choristoneura Lederer (Lepidoptera:
Tortricidae) in Canada and Alaska. Can. Entomol. 117: 1-5.
Daterman, G.E. 1974. Synthetic sex pheromones for detection survey of European pine shoot moth. U.S. Dept.
Agric. For. Serv. Res. Pap. PNW-180. 12 pp.
Gray, T.G., K.N. Slessor, G.G. Grant, R.F. Shepherd, E.H. Holsten, and A.S. Tracey. 1984. Identification and field
testing of pheromone components of Choristoneura orae (Lepidoptera: Tortricidae). Can. Entomol. 116:
51-56.
Harvey, G.T. 1967. On coniferophagous species of Choristoneura (Lepidoptera: Tortricidae) in North America. V
Second diapause as a species character. Can. Entomol. 99: 486-503.
Harvey, G.T. 1985. The taxonomy of the coniferophagous species of Choristoneura (Lepidoptera: Tortricidae): A
review. Recent advances in spruce budwomms research, Proc. CANUSA Spruce Budworms Res. Symp.,
Bangor, Maine, 1984. Ottawa, Ontario: Can. For. Serv. 527 pp.
McGregor, M. D. 1968. Occurrence of the sugar pine tortrix, Choristoneura lambertiana, in the Intermountain and
Northem regions. J. Econ. Entomol. 61: 1113-1114.
McGregor, M. D. 1970. Biological observations on the life history and habits of Choristoneura lambertiana
(Lepidoptera: Tortricidae) on lodgepole pine in southeastem Idaho and western Montana. Can. Entomol.
102: 1201-1208.
Mayr, E., E.G. Linsley, R.L. Usinger. 1953. Methods and principles of systematic zoology. McGraw-Hill, New
York. 328 pp.
Miller, C.A., E.G. Kettela and G.A. McDougall. 1971. A sampling technique for overwintering spruce budworm
and its applicability to population surveys. For. Res. Lab. Fredericton, New Brunswick, Inf. Rep. M-X-25
Can. For. Serv. Dept. of Fish. and For. 11 pp.
Powell, J. A. 1980. Nomenclature of nearctic conifer-feeding Choristoneura (Lepidoptera: Tortricidae): Historical
review and present status. U.S. For. Serv., Gen. Tech. Rept. PNW-100. 18 pp.
Robertson, J. L. 1979. Rearing the westem spruce budworm. U.S. For. Serv. Washington, D.C. CANUSA
pamphlet. 18 pp.
Silk, PJ., L.PS. Kuenen, S.H. Tan, W.L. Roelofs, C.J. Sanders and A.R.Alford. 1985. Identification of sex
pheromone components of jack pine budworm, Choristoneura pinus pinus Freeman. J. Chem. Ecol. 11:
159-167.
Silver, G.T. and D.A. Ross. 1964. Annual report forest insect and disease survey. Can. For. Serv., Ottawa, ON. p.
116.
Stark, R.W. and J.H. Borden. 1965. Life history of Choristoneura lambertiana subretiniana Obraztsov (Lepidop-
tera: Tortricidae) attacking lodgepole pine. Can. Entomol. 97: 684-690.
Stevens, R. E., T. K. Borg and T.I. Thatcher. 1977. Notes on a pine-feeding budworm, Choristoneura lambertiana
ponderosana (Lepidoptera: Tortricidae), in the Colorado Rockies. Can. Entomol. 109: 1269-1274.
Terrell, T.T. 1959. Sampling populations of overwintering spruce budworm in the northem Rocky Mountain
Region. U.S. For. Serv., Intermount. For. Range Exp. Stn. Res. Notes 61. 8 pp.
48 J. ENToMOoL Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
PROBABILITY OF DAMAGE TO SITKA SPRUCE BY
THE SITKA SPRUCE WEEVIL, PISSODES STROBI
RENE I. ALFARO
FORESTRY CANADA
PacIFIC FORESTRY CENTRE
506 West BURNSIDE ROAD
VICTORIA, BRITISH COLUMBIA
V8Z 1M5 CANADA
ABSTRACT
A nine-year record of attacks to Sitka spruce, Picea sitchensis (Bong.) Carr., by the
Sitka spruce weevil (=white pine weevil), Pissodes strobi (Peck), was analyzed to
determine the probability of attack on a tree based on the length of its terminal leader.
Equations describing the relationship were developed. Tall trees with long leaders had
higher rates of attack than short trees with short leaders.
Additional key words: Pest, impacts, insects, loss, Picea sitchensis.
RESUME
Les données compilées pendant neuf ans sur les dégats causés par le charanon du pin
blanc (Pissodes strobi Peck.) a des épinettes de Sitka (Picea sitchensis Bong.) ont été
analyses afin de déterminer les probabilités qu’un arbre soit attaqué d’aprés la longueur
de sa pousse apicale. Des équations reflétant cette relation ont été 4 aborées. Les arbres
de haute taille portant de longues pousses apicales étaient plus fréquemment attaqués
que les arbres de faible hauteur 4 pousses apicales courtes.
INTRODUCTION
The Sitka spruce weevil (=white pine weevil), Pissodes strobi (Peck), is the most damaging
pest of Sitka spruce, Picea sitchensis (Bong.) Carr., in coastal British Columbia, Washington
and Oregon. In early spring, adult weevils crawl or fly to the terminal leader of the previous
season and females lay eggs in niches excavated under the bark. The larvae kill the leader by
mining and consuming the phloem. Following an attack, the lateral branches from the whorl
immediately below the damaged leader develop negative geotropism and assume a vertical
position. This process usually results in the formation of crooks and forks at the point of injury
(Silver 1968, McMullen 1976, Alfaro 1989). Repeatedly attacked trees are stunted and
overtopped by competing vegetation; a severely attacked plantation may be worthless (Alfaro
1982).
Modern pest management is greatly assisted by computer models that integrate pest
biological and epidemiological factors into stand growth dynamics. Of particular importance
are the factors that determine whether a particular stand or an individual tree within a stand is
attacked. Several factors determine the rate at which Sitka spruce is attacked by the Sitka
spruce weevil. Because of a climate unfavorable to insect development, stands in coastal
locations and on the northern extremes of the distribution of Sitka spruce are less susceptible
than stands on inland or southern locations (McMullen 1976, Heppner and Wood 1984).
Similarly, a lower susceptibility of trees growing under shade, apparently caused by an
unsuitable microclimate, has been reported for the eastern host of P. strobi, the eastern white
pine (Pinus strobus L.) (Graham 1918; Wallace and Sullivan 1985), as well as for Sitka spruce
(McLean 1989).
Plantations in the most susceptible areas are infested when trees are about 4 to 5 years old;
attack intensity (number of trees attacked/year) increases rapidly thereafter, reaching a
maximum when the plantation is 10 to 30 years old (Alfaro 1982; McMullen et al. 1987). The
overall susceptibility of a stand decreases as trees reach heights above 12 m (Harris et al. 1968;
McMullen 1976, McMullen and Condrashoff 1973). This makes the Sitka spruce weevil a pest
of primarily young forests. Overhulser et al. (1972) indicated that weevil oviposition and
emergence is lower in trees that had previous attacks, relative to trees that had never been
J. Enromot Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 49
attacked. Based on this finding, they hypothesized that older plantations have lower attack
rates because they have a small number of unattacked trees and hence do not produce large
numbers of weevils.
Graham (1951) studied the attack records for a Sitka spruce plantation established in
1930-1932 at Green Timbers Nursery, in Surrey, British Columbia. He concluded that the
frequency of P. strobi attacks per tree could not be attributed to chance alone, but that some
trees had higher rates of repeated attack than others. Graham did not speculate on the reasons
for this non-randomness. In 1960, G.T. Silver, formerly with the Canadian Forestry Service in
Victoria, British Columbia, established four plots to study the biology of this insect and
possible means of control. Silver(1968) analyzed data collected in these plots between 1960
and 1963 and reported that the tallest trees in a stand, with the longest leaders, had higher rates
of attack than shorter trees with short leaders. Gara et al. (1971) and VanderSar and Borden
(1977) corroborated Silver’s (1968) findings. McMullen et al. (1987) and McLean (1989)
present figures that display the relationship between proportion ot trees attacked and their
leader length. However, these authors did not develop mathematical equations to quantify the
relationship. The pictorial relationship in McMullen et al. (1987) is one of the several
relationships used in a comprehensive population dynamics model these authors report in the
same paper.
McMullen et al. (1987) used data collected by Silver between 1960 and 1963. Silver
continued the measurement of his plots until 1968. In this paper I analyze Silver’s full 9-year
record and develop equations that describe the probability of a tree being attacked based on
leader length and on weevil population level.
MATERIALS AND METHODS
Silver’s 1960s Study
Four plots were established in the fall of 1959 in an area of natural Sitka spruce regeneration
which originated after clearcut logging, near Nitinat Lake on Vancouver Island. The plots were
rectangular, had a combined area of 1 ha, and initially included 692 trees which were marked
with metal tags. One plot was left untreated and the others treated in certain years with
insecticides. At the time of establishment, average tree age and height were 7 years and 1.3 m,
respectively. In the early spring of every year, from 1960 until 1968, each tree was examined
and tree height, the length of all leaders (including multiple leaders), and attack status (i.e.,
whether it was attacked or not) were recorded. Since the examinations were conducted before
growth started, they represented tree condition at the end of the previous growing season.
Data Analysis
The data used in this paper were obtained from Silver’s check plot; they therefore represent
uncontrolled damage levels. This plot occupied 0.32 ha and initially included 231 trees.
To describe the stand and trees being attacked each year, the distribution of tree heights and
leader lengths were tested for normality using the Kolomogorov test (Stephens 1983). This test
was also applied to tree heights and leader lengths sorted by attack status. The data for every
year were tested (Student’s t-test) for significant differences in height or leader length between
attacked and unattacked trees.
A logistic model (Hamilton 1974) was fitted to the binary attack data to relate the
probability of a tree being attacked to its leader length. Leader lengths were converted to
percentiles (Mendenhall 1975) of the leader length distribution for each year to allow
comparisons between years, which were independent of the mean value. This is important
because leader length increases with tree height and age up to a maximum which varies by site
quality. Therefore, a particular length of leader may be considered long or short depending on
plantation height and age at the time.
The probability of attack might depend not only on leader length but also on the level of the
weevil population in a particular year. For this reason, in addition to the logistic model,
separate linear models were calculated to describe the relationship between the percentage of
attack in trees sorted by leader length percentile class in years of different attack severity.
Severity classes were as follows:
50 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
LIGHT: the percentage of trees attacked in the year was 10% or less;
MODERATE: the percentage of trees attacked in the year was between 10% and
2 (os
SEVERE: the percentage of trees attacked in the year was greater than 20%.
The percentage of trees attacked refers to the percent of the stand trees attacked. Trees with
multiple leaders were considered attacked if they had an attack in at least one of the leaders.
RESULTS
Tree height at the end of the 1959 and 1968 growing seasons averaged 1.3 and 4.6 m,
respectively; the trees grew an average 3.3 m in the period. Leader length increased linearly
with tree height until the trees were 3 to 4 m tall; it then reached a plateau at about 60 cm of
growth per year (Figure 1). Fewer than 20% of the trees were attacked in the years from 1959
to 1961. The percentage of trees attacked reached a maximum of 36% in 1964; thereafter, the
attack rate oscillated around 30% per year (Table 1).
The tests of normality indicated that, in every year, tree heights were distributed normally.
Separate analysis of tree height distribution by attack status (attacked versus non-attacked)
indicated no significant departure from normality (Kolomogorov D statistic test, P> 0.05). The
distributions of the lengths of all leaders departed significantly from the normal distribution in
four of the nine years studied. The difference, however, was only minor (probability of the D
statistic was barely significant) and consisted of an excess frequency in the larger length
classes. The distribution of leader lengths in leaders sorted by attack status were generally
normal (Figure 2) with only two years in each class where a marginal departure from normality
occurred, again due to an excess number of long leaders. The distributions of tree heights and
leader lengths in attacked and non-attacked trees overlapped widely. In 1962, for example, the
weevil attacked leaders as short as 25 cm but declined to attack many trees with 50- to 80-cm
leaders.
Pissodes strobi preferred the tallest trees with the longest leaders in all years (Table 1). The
difference in height and leader length between attacked and non-attacked trees averaged 0.8 m
and 17.1 cm, respectively, over all years.
100
E
S 80
a=
O
a
ii 60
jem
LU
Q
n° 40
st
za
q
LU
=
l 2 3 4 5 6 7 8
TREE HEIGHT (m)
FIGURE 1. Average leader growth of Sitka spruce tabulated by height at the start of the season (trees grouped by
1-m height class)
J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 51
TABLE 1. Percentage of Sitka spruce trees attacked by the Sitka spruce weevil and height and leader length of
attacked and unattacked trees.
Year® Attack> Mean tree height (m) Mean leader length (cm)
(%) attacked not-attacked attacked not-attacked
1959¢ 18 2.0 1.444 37.0 22.0 5"
1960 9 23 1 Fed 48.0 33.0 **
1961 14 2.9 1.977% 56.7 33.6°4"
1962 28 3.1 22" 58.6 CAG Beles
1963 33 3.5 Poe whaged 62.5 44.0 **
1964 36 Sut 267" 62.6 55.1 ns
1965 35 3.9 Ss" 64.0 423 **
1966 29 4.3 3.6 * 58.7 so =*
1967 29 4.6 3.9 * 61.6 48.9 **
@Year of leader formation
bAttacks occurred 1 year after leader formation
¢ Average age in 1959 was 7 years.
dSignificance of difference between mean tree heights or leader lengths were tested by the Student t-test, and are
indicated by *=P< 0.05, **=P< 0.01, and ns= P> 0.05.
par
40
Papago 8, az
Oo X NOT ATTACKED
= |
S 4
uu os
eS 220 / a
Nou ae os X ATTACKED
ATTACKED ,/ . os
a mo Ad ®
10
ATTACKED
20 40 60 80 100
LEADER LENGTH / cm )
FIGURE 2. Frequency distribution of Sitka spruce leader lengths of trees attacked and not attacked by the Sitka
spruce weevil, Pissodes strobi, in a representative year (1962), near Nitinat Lake, Vancouver Island.
The logistic model:
P = {1+EXP (A + B X LLENGTH)}'! (1)
where P is the probability of a tree being attacked in a particular year, and LLENGTH is the
length of the leader as percentile of the leader length distribution for that year, and a = 2.816,
and b = -3.118, was highly significant (F=273, P<0.01). However, although this model
provided a good estimate of the average probability of attack in any year (Figure 3),
considerable variation remained unexplained (correlation coefficient = 0.33). This variation is
due, in part, to the fact that the probability of attack on a tree depends not only on the length of
the leader, but also on the population level of the weevil: in years of low population, a tree with
a en leader length will have a lower probability of attack than in years with a high
population.
52 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
1.0
e
x 0.8 e
O
= °
= @ @
q
u 0.6 e - ) @ ‘
oO 6 @
e e e
E ° $ a:
+ 0.4 e ¢ e ¢
a . e e ‘so, e e
(an) @ @ e
. ® { ee ae e
a 0:2 . 8 e 3 ‘
e ee ° @ ©
10 20 30 40 50 60 70 80 90 100
LEADER LENGTH CLASS ( PERCENTILES )
FIGURE 3. Percentage of attack (dots) and probability of attack (solid line) by Pissodes strobi weevils in Sitka
spruce leaders sorted by leader length class. Lengths were expresed as percentiles of the leader length distribution
for each year. The width of the percentile length class was 10%. These data were collected over 9 years near
Nitinat Lake, Vancouver Island.
The linear models for each severity class were highly significant (Fig. 4). The models were
refitted to eliminate non-significant intercepts, yielding the functions:
Population level LIGHT:
P= 0.002 x LCLASS
r2=0.68, F= 23.8
Population level MODERATE
P= -0.121 + 0.006 x LCLASS
r2= ().77, F= 60.9
Population level SEVERE:
P= 0.006 x LCLASS
r2= (0.71, F= 145.2
where P is the probability of a tree being attacked in a particular year; LCLASS is the midpoint
of leader length class (Length is expressed as a percentile of the leader length distribution.
Length classes have a width of 10% of the total length distribution, with mid-points at 5%,
15%, 25%, etc.); and LIGHT, MODERATE and SEVERE are population levels as defined in
the Methods section.
DISCUSSION
The attack rates increased from less than 20% to a maximum between 30% and 40% of the
trees per year. This epidemiological pattern is very similar to that reported by Alfaro (1982) for
a severely attacked plantation at Green Timbers, near Surrey, British Columbia and by
McMullen et al. (1987) in plantations in the Klanawa River area of Vancouver Island. Alfaro
(1982) indicated that attacked trees take 2 or 3 years to develop a new leader. During this
period, the tree is generally not available for re-attack, unless the tree has developed multiple
tops or the tree is re-attacked in the internode below the previous year’s attack. In the Prince
George area, Cozens (1987) found that in interior spruce (Picea glauca x engelmanni) up to
20% of the attacks were re-attacks on trees attacked in the previous year. Therefore, attack
rates of 30 to 40%, such as the ones reported here, are probably near the maximum attack rate
that a weevil population may sustain in a stand. Higher attack rates would deplete the
Oviposition sites and would lead to a reduction in the weevil population.
J. Enromo Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 53
1.0
0.8
0.6
PROBABILITY OF ATTACK
0.8
PROBABILITY OF ATTACK
0.8
0.6
0.4
0.2
PROBABILITY OF ATTACK
0 20 40 60 80 100
LEADER ILENGTH CLASS ( PERCENTILES )
FIGURE 4. Percentage of attack (dots) and probability of attack (solid line) by Pissodes strobi weevils in Sitka
spruce leaders sorted by leader length class. A) When attack intensity is LIGHT i.e. the percentage of trees
attacked in a stand is 10% or less; B) When attack intensity is MODERATE ce. the percentage of trees attacked in
a stand is greater than 10% but less than or equals to 20%; C) When attack intensity is SEVERE i.e. the percentage
of trees attacked in a stand is greater than 20%. Lengths were expresed as percentiles of the leader length
distribution for each year. The width of the percentile length class was 10%. These data were collected over 9 years
near Nitinat Lake, Vancouver Island. Dotted line represents the 95% confidence interval.
54 J. ENTOMOL Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
The fact that the frequency distributions of attacked and non-attacked leaders overlap
widely (Figure 2) suggests that, in addition to leader length and population level, other factors
determine whether a tree is attacked or not. My own unpublished observations indicate that the
spatial distribution of the weevil population and of the attacks in young plantations is clumped.
Attack intensity in trees within population clumps would be higher than that between clumps,
forcing the weevils to attack smaller leaders in the clump areas and leaving relatively longer
leaders unattacked in the areas between clumps.
The preference of P. strobi for the longest leaders in the stand is an adaptation of
significance to the survival of a weevil population. It ensures that the leaders with the
maximum food supply (more phloem in longer leaders) will be colonized; offspring produc-
tion per leader is therefore optimized.
The equations developed here could form an integral part of a pest management model such
as the one presented by McMullen et al. (1987), to predict the damage caused by the Sitka
spruce weevil to Sitka spruce in British Columbia.
REFERENCES
Alfaro, R.I. 1982. Fifty-year-old Sitka spruce plantations with a history of intense weevil attack. J. Entomol. Soc.
B.C. 79:62-65.
Alfaro, R.I. 1989. Stem defects in Sitka spruce induced by Sitka spruce weevil attack. Pages 177-186 in Alfaro,
R.I. and S. Glover, eds. Insects affecting reforestation: biology and damage. Proceedings of a IUFRO
symposium held on July 3-9, 1988, in Vancouver, B.C. Canada, under the auspices of the XVII
International Congress of Entomology.
Cozens, R.D. 1987. Second broods of Pissodes strobi (Coleoptera: Curculionidae) in previously attacked leaders
of interior spruce. J. Entomol. Soc. B.C. 84:46-49.
Gara, R.L, R.L. Carlson and B.F. Hrutfiord. 1971.Influence of some physical and host factors on the behaviour of
the Sitka spruce weevil, Pissodes sitchensis, in southwestern Washington. Ann. Entomol. Soc. Am.
64:467-471.
Graham, S. 1918. The white pine weevil and its relationship to second growth white pine. J. For. 16:192-202.
Graham, K. 1951. The Sitka spruce weevil. Bi-monthly Prog. Rep., Can. Dept. Agric. 7:3-4.
Hamilton, D.A., Jr. 1974. Event probabilities estimated by regression. USDA. For. Serv. Res. Pap. INT-152. 18 p.
Harris, J.W.E., J.C.V. Holms and A.C. Molnar. 1968. Status of the Sitka spruce weevil on Vancouver Island, 1967.
Can. Dept. For. and Rural Development, Forest Res. Lab., Victoria, B.C., Inf. Rep. BC-X-15, 19 p.
Heppner, D.G. and P.M. Wood. 1984. Vancouver Region Sitka spruce weevil survey results (1982-1983), with
recomendations for planting Sitka spruce. British Columbia For. Serv. Int. Rep. PM-V-S5.
Mendenhall, W. 1975. Introduction to probability and statistics. Duxbury Press. 460 p.
McLean, J.A. 1989. Effect of red alder overstory on the occurrence of Pissodes strobi (Peck) during the
establishment of a Sitka spruce plot. Pages 167-176 in R.I. Alfaro, and S. Glover, eds. Insects affecting
reforestation: biology and damage. Proceedings of a IUFRO symposium held on July 3-9, 1988, in
Vancouver, B.C. Canada, under the auspices of the XVIII International Congress of Entomology.
McMullen, L.H. 1976. Spruce weevil damage. Ecological basis and hazard rating for Vancouver Island. Can. For.
Serv. Pac. For. Res. Cent. Inf. Rep. BC-X-141. Victoria, B.C. 7 p.
McMullen, L.H. and S.F. Condrashoff. 1973. Notes on dispersal, longevity and overwintering of adult Pissodes
strobt (Peck) (Coleoptera: Curculionidae) on Vancouver Island. J. Entomol. Soc. B.C. 70:22-26.
McMullen, L.H., A.J. Thomson and R.V. Quenet. 1987. Sitka spruce weevil (Pissodes strobi) population
dynamics and control: A simulation model based on field relationships. Can. For. Serv. Pac. For. Cent. Inf.
Rep. BC-X-288. Victoria, B.C. 20 p.
Overhulser, D., R.I. Gara and R. Johnsey. 1972. Emergence of Pissodes strobi (Coleoptera:Curculionidae) from
previously attacked Sitka spruce. Ann. Entomol. Soc. Am. 65:1423-1424.
Silver, G.T. 1968. Studies on the Sitka spruce weevil, Pissodes sitchensis, in British Columbia. Can. Entomol.
100:93-110.
Stephens, M.A. 1983. Kolomogorov-Smirnov statistic. P. 393-396, in S. Kotz and N.L. Johnson (Chief editors),
Encyclopedia of Statistical Sciences, Vol.4. John Wiley and Sons, New York.
VanderSar, T.J.D and J.H. Borden. 1977. Visual orientation of Pissodes strobi Peck (Coleoptera: Curculionidae) in
relation to host selection behaviour. Can. J. Zool. 55:2042-2049.
Wallace, D.R. and C.R. Sullivan. 1985. The white pine weevil, Pissodes strobi (Coleoptera: Curculionidae): a
review emphasizing behaviour and development in relation to physical factors. Proc. Entomol. Soc. Ont.
Suppl. 116:39-62.
J. ENToMOoL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 55
A POTENTIAL COLLECTION METHOD FOR AGAPETA ZOEGANA
(LEPIDOPTERA: COCHYLIDAE), A KNAPWEED-ROOT-FEEDING MOTH
SHEILA M. FirzPATRICK
AGRICULTURE CANADA RESEARCH STATION
6660 N.W. MARINE DRIVE
VANCOUVER, B.C. V6T 1X2
ABSTRACT
This paper describes a method for collecting living, undamaged Agapeta zoegana
(L.) moths, especially recently mated females. The objective was to gather this potential
biological control agent for subsequent distribution to land infested with knapweeds
(Centaurea spp.) Sweep-netting and baiting techniques were inappropriate collection
methods, because the moths were delicate and did not appear to forage. The moths did
not move to the plant tops at particular temperatures or times of day and therefore could
not easily be collected by aspiration. However, males and virgin and mated females
within large field cages were attracted to UV light and, during their daily period of
reproductive activity from dusk to midnight, could be collected in a Heliothis trap
(Sentry) illuminated by a blacklight. In the open, neither this method nor a mobile-
blacklight technique were successful in 1988, but both warrant further work. Results are
discussed in the context of A. zoegana establishment in B.C.
INTRODUCTION
Diffuse (Centaurea diffusa Lam.) and spotted (C. maculosa Lam.) knapweed, introduced
from Europe in the early 1900’s, pose a serious threat to range- and pasture-lands in B.C.
(Cranston, 1980). The knapweeds outcompete native forage species on disturbed or over-
grazed sites, and are of low value as forage (Harris and Myers 1984). Chemical control of
knapweed in most areas is neither economically practical nor environmentally desirable
(Cranston 1980). Therefore, recent research has concentrated on introducing biological
control agents from knapweed habitats in Europe (e.g. Harris and Myers 1984; Muir and
Harris 1986, 1987).
The knapweed-root-feeding moth, Agapeta zoegana (L.), was introduced from Europe in
1982, 1983 and 1984 (Muir and Harris 1987). However, unlike previous releases of other
natural enemies of knapweed (the seed flies, Urophora affinis (Frfld.) and U. quadrifasciata
Mg.; the moth, Metzneria paucipunctella (Zeller) (Harris and Myers 1984); and the beetle,
Sphenoptera jugoslavica (Obenb.) (Powell and Harris 1986)), introduction did not result in
establishment (Muir and Harris 1987). Efforts to import enough A. zoegana larvae for
subsequent releases were unsuccessful, since many larvae shipped from Europe died from
parasitism and other factors, and because knapweed habitats in Europe were fast disappearing
(Muir and Harris 1987). Therefore, a propagation facility, operated by the B.C. Ministry of
Forests, was set up at the Agriculture Canada Research Station in Kamloops, B.C.
Since 1985, A. zoegana has been reared successfully on cultivated knapweed enclosed in
large steel-frame field cages, then released onto knapweed infestations in B.C. (Muir and
Harris 1987). It is hoped that A. zoegana will become established and amenable to collection
from these sites for distribution elsewhere (R. Tucker, pers. comm.). However, there is little
evidence of establishment to date.
I have attempted to develop a technique for collecting large numbers of undamaged A.
zoegana moths, especially recently mated females. I considered three methods: sweep-netting,
as used for the two Urophora species (Harris 1986a,b) and for S. jugoslavica; attraction to
sugary baits (Borror et al. 1976); and attraction to a blacklight live-trap (Frost 1952, Mikkola
1972). Experience showed that A. zoegana moths were too delicate to be collected by sweep-
netting and unlikely to be attracted to sugary baits, as adults have never been seen nectaring,
either during the day (V. Fediuk, H. Miiller, pers. comm.), or at night (pers. obs.). However, A.
zoegana moths are attracted to UV light between dusk and midnight (Tucker and Fediuk
1987). Therefore, a blacklight live-trap seemed the collection method most likely to succeed.
56 J. ENtomot Soc. Brit. CoLUMBIA 86 (1989), Sept. 30, 1989
To determine the optimum time for trapping, I quantified nocturnal activity patterns. Because
light traps often attract more males than females (Mikkola 1972), I paid particular attention to
reproductive behaviour that might result in male- biased catches. I also observed diurnal
activities to see if the moths ever moved up to the plant tops from which they could be
collected by aspiration.
MATERIALS AND METHODS
All observations of A. zoegana activity were carried out from June until August, 1988, on
moths maintained in 12 steel- frame field cages (3 x 3 x 2.5 m high) at the Kamloops rearing
facility. Kriapweed (predominantly spotted) within the enclosures was planted from seed,
watered, weeded and fertilized. A. zoegana moths, which are bright yellow and ~1 cm long,
began emerging from below-ground pupation sites in mid-June. Although moths apparently do
not nectar, two feeders, each consisting of a honey-soaked wick in a 50-ml Erlenmeyer flask,
were suspended 5 cm above the knapweed canopy in each cage, and renewed every few days.
Mated females oviposited on knapweed foliage from June until August, and neonate larvae
migrated to the roots where they fed, reducing the plant vigour, until pupation. Predators such
as ants and spiders were excluded by applications of insecticide (carbaryl) around the outer
boundaries of each cage. Predators seen within cages were killed by hand.
To quantify the diurnal movement of these sedentary moths, I measured their heights within
the canopy as a function of time and temperature. Temperatures were read from a max-min
thermometer suspended 5 cm above the tallest knapweed plants in one of the cages.
At night, moths perching within or flying above the canopy were not easily seen. Therefore,
I compared day- and nighttime activity by counting the number of moths perching on the cage
walls above the canopy. Night observations were carried out by the light of a flashlight
dimmed with several layers of paper towel and filtered (Kodak Wratten #29) to exclude all
wavelengths but red, to which moths are least sensitive (Mikkola 1972). As observations
indicated that moth activity was greatest at and after dusk, I assessed reproductive activity at
this time by observing females confined in net sleeve-cages (45 x 15 cm) placed over
knapweed plants. The mating status and egg complement of these females was determined by
dissection. A. zoegana males transfer a spermatophore (a mass of sperm and accessory gland
secretions enclosed in a cuticular sac (Rutowski 1979; Drummond 1984) to the female
reproductive tract during mating. Tracts of mated A. zoegana females contained either a full
spermatophore or one or two partially or fully collapsed cuticular sacs. Females have two
ovaries, each consisting of four ovarioles filled with oocytes (Fitzpatrick 1988), most of which
were filled with yolk and yolk precursors and appeared white, while those nearest the terminal
filament (Happ 1984) were smaller and clear.
The blacklight live-trap was a Heliothis trap (Sentry; and see Webster et al. 1986) suspended
15 cm above the tallest knapweed plants, and illuminated from the top by a mining-type
blacklight (principal wavelength 360 nm; Fig. 1). The trap’s lower cone was covered with
white organdy cloth to enhance UV reflectance. Knapweed below the trap was parted to allow
a white cloth to be placed there. Care was taken to shield the worker’s eyes from direct UV
rays. Power was provided by a portable Honda generator of 1 kW. In one instance, the
blacklight was placed behind a sheet of white cotton stretched over a frame (20 x 20 cm) and
mounted on the front of a four-wheel-drive all-terrain- vehicle (Honda 4-Track) to provide a
moving collection device. Moths needed for field tests of collection devices were aspirated
with an Insect Vac (Bioquip) from field cages.
The data were tested by analysis of variance (ANOVA) followed, if appropriate, by Tukey’s
test. Chi-square tests were applied to frequency data.
J. ENTOMOL Soc. BRIT. COLUMBIA 86 (1989), SEPT. 30, 1989 aT
80cm
“ aa
B
\ yp Niip Wie \ Wi \le Nie Ile ee
KNAPWEED
Figure 1. Schematic lateral view of blacklight live-trap. Moths, attracted by blacklight suspended at (A),
enter the lower cone (B) of the Heliothis trap (Sentry) and fly up to the containment chamber (C), which
can be removed by releasing Velcro at (D).
RESULTS AND DISCUSSION
Diurnal and nocturnal activity
A. zoegana moths remained within the knapweed canopy during the day, rarely flying. Of 28
moths observed every 2 h on June 24, 53% remained in one place from 0800 h (20.0°C) until
1500 h (30.0°C). On warm days (e.g. July 14; Fig. 2B) most moths were found in the middle to
upper canopy, while on an unseasonably cool, windy day (June 30; Fig. 2A) they remained in
the lower half. The moths showed no daily vertical migration to the top of the canopy, although
in one case (June 30-July 1) their mean height was significantly greater at 0800 h than at 2000
h the previous evening (Fig. 2; ANOVA on heights). Therefore, aspirating the moths from
plant tops was not a feasible collection method.
From morning until mid-afternoon, A. zoegana moths were usually difficult to disturb. They
were most easily startled into flight in late afternoon and early evening, when they made short
flights of 1-2 s to nearby plants or cage walls. About dusk, many of both sexes flew in 3-4 s
zigzagging flights up onto the cage walls above the canopy (Fig. 3; cf. Muir and Harris, 1987).
Despite efforts to control predators, spiders caught many of the moths perching on the walls,
particularly early in the season (Fig. 3). The moths did not fly during cool, cloudy, windy
weather.
38 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
100 [a] 40
80 30
dh
(oe)
HEIGHT CM
o
Oo
N
fo)
N
ie}
100 40
O
80 30°
a
= Ss
O Ww
60 20 F
-
= ~
< 40-6 10
i in
5 es <—
E
20-6
x 53
b4
oO
£
O
8 10 12 14 1146 #418 £20 8 10
TIME H
Figure 2. Mean heights (+ 1 standard error) of A. zoegana moths perching within the knapweed canopy in
field cages at the Kamloops Research Station on (A) June 30 - July 1 and (B) July 14-15, 1988. Number
of moths observed is shown within each histogram. Daytime temperatures are shown @——®. Minimum
temperatures, recorded about dawn, were 10.0°C on July 1 and 5.0°C on July 15.
Female activity was monitored on three nights. On June 16, two females were placed in a
sleeve cage over a spotted knapweed plant, and observed hourly from 2200-0400 h
(22.0-13.5°C). Both moved to the top of the cage at dusk (~2200 h). One female was observed
Ovipositing at 2200, 2300 and 2400 h, while the other was seen in the “calling’’ posture,
described by Turgeon and McNeil (1982), at 2300 and 2400 h. Both females then remained
stationary at the top of the cage for the rest of the night. On June 23, six females were confined
to a sleeve cage and observed every 15 min from 2100-0030 h (18.5-11.0°C). The same
females were observed every 20 min from 2100-2320 h (22.5-18.5°C) on June 24. One female
began ovipositing several minutes before 2100 h on both evenings, and continued in bouts
until 2245 h (16.0°C) June 23 and 2240 h (18.0°C) June 24. The remaining five females moved
to the top of the cage between 2145 h (17.5°C) and 2300 h (16.0°C) June 23, and between 2100
h (23.0°C) and 2140 h (21°C) June 24, where they alternately fluttered and perched. None of
the five was observed calling or ovipositing, and all six stayed motionless near the top of the
cage after 2300 h.
J. ENTOMOL Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989 59
The female that called on June 16 contained 189 white eggs but no spermatophore,
indicating that she had not been mated, while the other deposited ~100 eggs on the cage and
contained 55 white eggs plus a partially collapsed spermatophore. Status of the six females
observed on June 23-24 is shown below.
Number of eggs
Female White Clear Total Spermatophore
1 128 79 207 1
Z 252 149 401 0
3 141 127 268 0
4 51 80 131 1
5 140 136 276 0
6 160 140 300 ?
The only female seen ovipositing on those nights was #4, identified by her worn appearance.
All the females dissected in the course of this study (Fitzpatrick 1988) contained more eggs
than previously reported for this species (Miiller et al. 1988).
Since moths of both sexes were active from dusk until midnight, I ran the blacklight trap
during that period. I expected that the trap might capture proportionally more males, which
were probably flying through and above the knapweed canopy in search of mates, than females
which, although found above the canopy at dusk, probably returned to knapweed plants shortly
thereafter to call or to oviposit.
Blacklight-trap tests: Within field cages
The blacklight trap (Fig. 1) was tested on four occasions. On the first, it was used from 2100
h on June 30 (1.5 h before total darkness) until early dawn at 340 h on July 1, in a field cage
containing 10 males and 16 females. The minimum temperature that evening was 10.0°C. To
encourage moths to fly up out of the canopy, the plants were disturbed with a stick at 2300 h
(11.0°C) and 2325 h (12.0°C). At least 10 A. zoegana moths were observed in and on the trap
at 2300 h. The next morning, five males and three females (at least one mated) were recovered
from the trap. Although this sex ratio did not differ statistically from that in the cage, 13 of the
16 females were not trapped. This may have been due to windy, cloudy conditions and
unseasonably cool temperatures that day and evening. A. zoegana females have larger body
masses than males (pers. obs.), and may need a higher ambient temperature than males to
initiate and sustain flight (as do Thymelicus lineola (Ochsenheimer) females (Pivnick and
McNeil 1986)).
On July 14-15, the trap was illuminated from 2130-0300 h (15.0-8.0°C) and the plants were
disturbed with a stick at 2200, 2300 and 2330 h. The trap caught 36 males and 13 females (six
mated, four unmated, one of unknown status). This male-biased ratio was not significantly
different from the ratio of 45 males to 19 females in the cage. All six untrapped females had
been mated.
To determine if canopy disturbance had any adverse effect on trap catch, plants were left
untouched during the following two tests. On July 15-16, from 2130-0300 h (13.0-7.0°C), the
trap caught 40 males and five mated females. Only three males and three females were not
trapped. The sex ratio of trapped moths was not different from the original male:female ratio.
On July 28-29, when the trap was run from 2115-0300 h (22.0-10.0°C), 24 males and 4 mated
females were collected. This ratio was not different from the original ratio in the cage. Of the
six females not trapped, five were mated.
Thus the trapping method used was effective over a short range. The trap catch was neither
increased nor reduced by flushing moths out of the knapweed.
60 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
[a] 40
100
>
O
2 80 30 O
xq
O
a
Lu
> 60 202
E
<x
S| 40 10
x
O
O
N] 20 0
<|
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XN oO pele eles
100 40
a O
ao 80 30>
za
e a
s
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O
a
= 40 10
rg
za
GS
SO! 20 0
O
N
<I oUUoo no
ee
10 14 18 22 2 6 10
TIME H
Figure 3. Activity of A. zoegana moths observed inside field cages on (A) June 16-17 and (B) July 14-15,
1988. Histograms show the percentage of moths seen above the knapweed canopy on cage walls. Total
number of moths observed was: (A) 35 from 1000-1800 h and 15 thereafter; (B) 52 until 0600 h and 55
thereafter. Hatched portions of histograms show moths captured by spiders. Scotophase (dusk to dawn) is
shown by solid bars along X-axes and temperatures are shown @——®.
Blacklight-trap tests: In the open
The blacklight trap was tested three times in the field. The first test took place at a 1987
release site near Clearwater, where A. zoegana larvae had been recovered early in 1988 (V.
Fediuk, pers. comm.). Two A. zoegana moths, one worn and one apparently newly emerged,
were observed in this area at 2230 h July 21. The trap was illuminated from 2130-0300 h
(19.5-12.0°C) and knapweed in a 50-m radius around it was disturbed with a stick at 2200,
2230 and 2300 h. A single A. zoegana male was captured, with many other insects. On July 22,
J. ENTOMOL Soc. BRIT. COLUMBIA 86 (1989), SEPT. 30, 1989 61
two workers spent a total of 4h or 2 h each examining all knapweed plants in a 100 x 10 m area
surrounding the trap. No A. zoegana were sighted there, nor were any seen during a wider but
less-thorough search. Given the sedentary nature of the moths during the day and the fact that
both searchers were accustomed to looking for A. zoegana, it is unlikely that the bright yellow
moths went unnoticed. There were probably too few A. zoegana to allow for an accurate test of
the trap.
An established population of A. zoegana could not be found, so the next two tests used
moths aspirated from the field cages at the Kamloops Research Station and released at a
nearby spotted knapweed infestation. At 1030 h on August 4, 100 moths (51 males and 49
females) were released onto two clumps of knapweed 20 m apart (~50 moths/clump). Moths
flew to the knapweed immediately upon release. Within 1 min of release, one A. zoegana moth
had to be rescued from an ant that was dragging it away. Although some moths probably fell
prey to the numerous ants in the area, at least 10 moths were observed at the release site 10 h
later. The trap was set up midway between the two release points, and run from 2100-0300 h.
The knapweed was disturbed with a stick every half-hour from 2130 to 2300 h (25.0, 23.0, 21.0
and 20.0°C, respectively), but only three males were caught, and all were in the trap by 2300 h.
Thus the blacklight trap, which worked well in a small enclosure, was not effective under
these field conditions. Since A. zoegana adults would not come to the blacklight in the field,
we attempted to take the blacklight to them.
In the final test, 136 moths (53 males and 83 females) were released on three clumps of
knapweed (~45 moths/clump) at 1700 h on August 18. The blacklight was attached to the front
of a four-wheel all-terrain vehicle (ATV) at headlight level, and covered with a piece of white
cotton, 20 x 20 cm, stretched over a wooden frame. At 2115 h (15.0°C), the ATV made 5 non-
overlapping passes through the release area. Three male A. zoegana landed on the cloth and
remained there long enough to be aspirated off.
Neither blacklight method was a success but both warrant further testing. The first test at
Clearwater may have failed due to a paucity of A. zoegana. The second and third may have
failed because the moth’s behaviour was altered by capture and transport, or because released
moths were quickly taken by predators. More work with established field populations of A.
zoegana is needed.
A. zoegana establishment in B.C.
Some of these results suggest that ecological factors may account for the apparent failure of
A. zoegana to become established, e.g. climatic adaptation. A. zoegana habitats in Europe are
generally warm enough for the insect to complete two or three generations per year (Miiller et
al. 1988) whereas in the B.C. interior, A. zoegana is restricted to one (Muir and Harris 1987).
Other factors are soil-moisture conditions and type of knapweed. Released A. zoegana seem
most likely to survive on moist, cool, stands of spotted knapweed (e.g. Clearwater) rather than
on dry, warm sites where diffuse knapweed predominates (V. Fediuk, R. Tucker, pers. comm.).
Diffuse knapweed often germinates from seed each spring and dies in fall, making it
impossible for root-inhabiting insects to overwinter (V. Fediuk, pers. comm.).
Plant vigour probably affects larval development and adult fecundity. Larval development
on cultivated vs. field knapweed has not been assessed, but it is known that the Kamloops
rearing facility yielded females containing from 150-400 eggs (Fitzpatrick 1988), fecundities
greater than the maximum of 95 eggs laid by females reared in Europe from field-collected
larvae (Miiller et al. 1988). It is important to know what proportion of moths reared on
cultivated knapweed will leave progeny able to survive on field knapweed.
Nothing is known of predation on A. zoegana adults in Europe or B.C., although several
parasitoids and predators of larvae in Europe have been identified (Miiller et al. 1988, 1989).
My observations suggest that predation by ants and spiders may represent a significant
mortality factor to A. zoegana moths here.
Finally, the sex ratio of released moths and the timing of release deserve consideration.
62 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
Early in the emergence period, males predominate (Muir and Harris 1987). Prior to 1988, the
moths were not sexed before release, thus some areas may have received males only. Releases
should probably coincide with the appearance of new growth because females apparently
prefer to oviposit on succulent tissue (H. Miiller, pers. comm.), whether on plant tops
(Fitzpatrick 1988; V. Fediuk, pers. comm.) or on rosettes (Miiller et al. 1988). Foliage quality
at the oviposition site may be important to the survival of neonate larvae, which appear to mine
the foliage slightly on their way to the roots (unpub. data).
Further work on any of these is needed.
ACKNOWLEDGEMENTS
I am grateful for the excellent technical assistance of Virginia Fediuk. I thank Dr. A.
Roberston and Harriet Douwes, of Agriculture Canada, Kamloops, for providing facilities and
equipment; Dwayne Brooks, Linda Edwards and Rick Tucker for helpful suggestions; and
Dave Tweedhope for driving the all- terrain vehicle used in the light-trap field test. Thanks also
to Dr. H. R. MacCarthy for helpful criticism of the manuscript. This work was done under
contract to B.C. Ministry of Forests while the author was employed by Integrated Crop
Management Services, Okanagan Centre, B.C.
REFERENCES
Borror, D.J., D.M. DeLong and-C.A. Triplehorn. 1976. An Introduction to the Study of Insects, Fourth Edition.
Holt, Rinehart and Wilson, U.S.A. pp. 728-729.
Cranston, R. 1980. Knapweed, its cause and effect in British Columbia. B.C. Ministry of Agriculture, Parliament
Buildings, Victoria, B.C. V8W 2Z7.
Drummond, B.A. III. 1984. Multiple mating and sperm competition in the Lepidoptera, pp. 291-370 in R.L. Smith
(ed.) Sperm Competition and the Evolution of Animal Mating Systems. Academic Press, Orlando, U.S.A.
Fitzpatrick, S.M. 1988. Development of a method for field collection of Agapeta zoegana (L.), a knapweed-root-
feeding moth. B.C. Ministry of Forests, 515 Columbia St., Kamloops, B.C. V2C 2T7.
Frost, S.W. 1952. Light traps for insect collection, survey and control. Bull. Pa. Agric. Exp. Stn. 550, 32 pp.
Happ, G.M. 1984. Development and reproduction, pp. 93-113 im H.E. Evans (ed.) /nsect Biology. Addison-
Wesley, U.S.A.
Harris, P. 1986a. Biological control of knapweed with Urophora affinis (Frfld.). Canadex 641.613, Agriculture
Canada, Communications Branch, Ottawa. K1A 0C7.
Harris, P. 1986b. Biological control of knapweed with Urophora quadrifasciata Mg. Canadex 641.613, Agricul-
ture Canada, Communications Branch, Ottawa. K1A 0C7.
Harris, P. and J.H. Myers. 1984. Centaurea diffusa Lam. and C. maculosa Lam. s. lat., diffuse and spotted
knapweed (Compositae), pp. 127-137 in J.S. Kelleher and M.A. Hulme (eds.) Biological Control Pro-
grammes Against Insects and Weeds in Canada 1969-1980. Commonwealth Agricultural Bureaux, London.
Mikkola, K. 1972. Behavioural and electrophysiological responses of night-flying insects, especially Lepidoptera,
to near ultra-violet and visible light. Ann. Zool. Fenn. 9: 225-254.
Muir, A.D. and P. Harris. 1986. Biological control of knapweed in British Columbia, 1985 Annual Report. B.C.
Ministry of Forests, Knapweed Containment and Control Program, 1450 Government St., Victoria, B.C.
V8W 3E7.
Muir, A.D. and P. Harris. 1987. Biological Control of Knapweed in British Columbia, 1986 Annual Report. B.C.
Ministry of Lands and Forests, Integrated Resource Branch (Range Section), Research Branch, 1450
Government St., Victoria, B.C. V8W 3E7.
Miller, H., D. Schroeder and A. Gassman. 1988. Agapeta zoegana (L.) (Lepidoptera: Cochylidae), a suitable
prospect for biological control of spotted and diffuse knapweed, Centaurea maculosa Monnet de la Marck
and Centaurea diffusa Monnet de la Marck (Compositae) in North America. Can. Ent. 120: 109-124.
Miiller, H., C.S.A. Stinson, K. Marquardt and D. Schroeder. 1989. The entomofaunas of roots of Centaurea
maculosa Lam., C. diffusa Lam., and C. vallesiaca Jordan in Europe. Niche separation in space and time. J.
Appl. Ent. 107: 83-95.
Pivnick, K.A. and J.N. McNeil. 1986. Sexual differences in the thermoregulation of Thymelicus lineola adults
(Lepidoptera: Hesperiidae). Ecology 67: 1024-1035.
Powell, R. and P. Harris. 1986. Biological control of diffuse knapweed by Sphenoptera jugoslavica (Obenb.).
Canadex 641.613, Agriculture Canada, Communications Branch, Ottawa. K1A 0C7.
Rutowski, R.L. 1979. The butterfly as an honest salesman. Anim. Behav. 27: 1269-1270.
Tucker, R. and V. Fediuk. 1987. Biological control of range weeds. 1987 Annual Report. B.C. Ministry of Forests,
515 Columbia St., Kamloops, B.C. V2C 2T7.
Turgeon, J.J. and J.N. McNeil. 1982. Calling behaviour of the armyworm, Pseudaletia unipuncta. Ent. Exp. Appl.
31: 402- 408.
Webster, R.P., R.E. Charlton, C. Schal and R.T. Cardé. 1986. High-efficiency pheromone trap for the European
com borer (Lepidoptera: Pyralidae). J. Econ. Ent. 79: 1139-1142.
J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 63
PARASITISM OF ORANGE TORTRIX ON CANEBERRY, RUBUS SPP. IN
WESTERN OREGON AND WASHINGTON
LEONARD Coop, ALAN KNIGHT!, AND GLENN FISHER
DEPARTMENT OF ENTOMOLOGY
OREGON STATE UNIVERSITY
CORVALLIS, OREGON 97331
ABSTRACT
Larvae and pupae of Argyrotaenia citrana (Fernald), were collected from commercial
caneberry fields, Rubus spp., in western Oregon and Washington from 1981 to 1984 and
reared in the laboratory to identify parasitoid species and determine levels of parasitism.
Twelve species of Hymenoptera (Braconidae, Eulophidae, and Ichneumonidae) and one
species of Diptera (Tachinidae) were identified. Over 80% of total parasitism was by the
braconids, Apanteles aristoteliae Viereck and Meteorus argyrotaeniae Johansen. M.
argyrotaeniae was also reared successfully from several other leafroller hosts: Cho-
ristoneura rosaceana (Harnis), Archips rosana L., and Cnephasia longana (Haworth).
No other hosts of A. aristoteliae were collected in caneberries.
Key Words: Argyrotaenia citrana, caneberry, Rubus, parasitoids
INTRODUCTION
The orange tortrix, Argyrotaenia citrana (Fernald), (Lepidoptera: Tortricidae), is an occa-
sional pest of a wide variety of fruit crops along the Pacific coast of North America (Powell
1964). In the Pacific Northwest orange tortrix can be an important pest of red raspberry, Rubus
idaeus L. and other Rubus cane fruits (Breakey & Batchelor 1948, Rosenstiel 1949, LaLone
1980, Knight et al. 1988). Larvae generally do not feed directly on fruit, but contaminate
harvested fruit, especially that which is machine harvested (Kieffer et al. 1983). Recent
biological studies of orange tortrix have reported on overwintering mortality factors (Knight &
Croft 1986), phenology (Coop 1983, Knight & Croft 1987a), and regional population
dynamics (Knight & Croft 1987b). These studies have led to the development of an effective
management program using sex pheromone traps to monitor populations that has reduced
unnecessary early season applications of insecticides (Knight et al. 1988).
This reduction of insecticide usage in caneberry may prove to be very important in
enhancing biological control of orange tortrix. Although parasitoids have been given credit for
reducing orange tortrix abundance on a number of crops (Anonymous 1926, Basinger 1935,
Rosenstiel 1949, Breakey 1951, Madsen & McNelly 1961, Kido et al. 1981), very little
biological or host information is recorded for must of the complex (Krombein et al. 1979).
Therefore, a study was initiated to identify larval and pupal parasitoid species and record
levels of parasitism in commercial caneberry fields. Data were also collected on the parasitism
of alternate lepidopterous hosts within caneberry.
MATERIALS AND METHODS
Commercial fields of red raspberry, R. idaeus L.; marionberry, R. ursinus Cham. &
Schlecht; and evergreen blackberry, R. laciniatus Willd. located in W Oregon and SW
Washington were sampled from 1981 through early 1984. Each field was sampled several
times from April through October, except for 1983 and 1984 when fields were sampled bi-
weekly from April through May. During early spring, leafroller larvae and pupae were
collected from dead leaves tied along the wire trellises. In summer and fall, leafroller larvae
were collected primarily from terminal leaf clusters along canes. All larvae and pupae were
reared in 28 ml plastic cups with artificial diet (Lyon et al. 1972) at 20 + 1°C, >70% RH, and a
photoperiod of L:D 16:8 h.
64 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
RESULTS AND DISCUSSION
Thirteen primary and two secondary parasitoid species were identified from over 2000
orange tortrix larvae and pupae that were field collected (Table 1). Parasitism in the samples
TABLE 1
Summary of parasitoid species reared from orange tortrix larvae and papae collected from
commercial caneberry Rubus ssp. fields in western Oregon and Washington, 1981-1984.
Other hosts>
Species Family Mode? Cr Ar Cl
Apanteles aristoteliae Viereck Braconidae larval endo solitary no no no
Meteorus argyrotaeniae Braconidae larval endo solitary yes* yes* yes*
Johansen
Phytodietus vulgaris Cresson _—_ Ichneumonidae larval ecto solitary no no _ yes*
Enytus eureka (Ashmead) Ichneumonidae larval endo solitary yes yes yes
Diadegma ssp. Ichneumonidae larval endo solitary yes no_ yes
Oncophanes americanus (Weed) Braconidae larval ecto greg yes no yes*
Meteorus dimidiatus* (Cresson) Braconidae larval endo solitary yes no no
Meloboris sp Ichneumonidae larval endo solitary no yes no
Meteorus trachynotus Viereck Braconidae larval endo solitary no no no
Parania geniculata* (Holmgren) Ichneumonidae _larval-pupal endo solitary no no no
Pseudoperichaeta erecta Tachinidae larval-pupal endo solitary yes no no
(Coquillet)
Elachertus* sp Eulophidae larval ecto solitary yes no no
Itoplectis quadricingulata (Prov) Ichneumonidae pupal endo solitary no no no
Stictopisthus sp Ichneumonidae hyper on A. aristoteliae no no no
Spilochalcis™ sp Chalcididae hyper on A. aristoteliae no no no
a Mode of parasitism is categorized as either larval, larval-pupal or hyperparasitism;
endoparastitism or ectoparasitism; and solitary or gregarious parasitism.
b Other hosts include: Choristoneura rosaceana, Archips rosanus, and Cnephasia longana.
* Represents a new host record.
ranged from 0 to 56% and averaged 27.5%. The braconids, Apanteles aristoteliae Viereck and
Meteorus argyrotaeniae Johansen, were the most commonly and widely collected species in
our samples, accounting for > 80% of the parasitoids reared. The ichneumonids, Enytus eureka
(Ashmead) and several unidentified species of Diadegma, were also commonly collected
though parasitism levels were generally very low, i.e. < 5%. The two ectoparasitoids,
Phytodietus vulgaris Cresson and Oncophanes americanus (Weed), were collected from only
a few sites during late summer and early fall. Yet, levels of parasitism averaged 9 and 14% for
these two species, respectively, when they were present in collections. Seven additional
parasitoid species were also collected, but only occasionally (Table 1). Of these, Parania
geniculata (Holmgren), Meteorus dimidiatus (Cresson), and Elachertus sp. are new host
parasitoid records (Krombein et al. 1979). Itoplectis quadricingulata (Provancher), the only
pupal parasitoid collected, was widely distributed among fields. A few specimens of the
hyperparasitoids, Stictopisthus sp. and Spilochalcis sp. were reared from A.. aristoteliae
cocoons.
Parasitoids were also reared from larvae of three other leafroller species occasionally found
J. ENromov Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 65
in caneberry: Choristoneura rosaceana (Harris), Archips rosana (L.), and Cnephasia longana
(Haworth). Seven species reared from C. rosaceana, two species reared from A. rosana, and
five species reared from C. longana were also collected from orange tortrix (Table 1).
Interestingly, M. argyrotaeniae was collected from all four hosts, but A. aristoteliae was
restricted to orange tortrix.
These other three leafrollers are polyphagous (Powell 1964) and are common pests of filberts,
Corylus avellana L. (AliNiazee 1980). The proximity of caneberry fields and filbert orchards
to one another and the dispersal capacity of both hosts and parasitoids may be important in
maintaining this complex of parasitoid species in the geographical region studied during
periods when suitable stages of orange tortrix are not available. In contrast, it is not clear what
importance temporal asynchrony of A. aristoteliae and orange tortrix populations in the spring
and the apparent lack of alternative hosts has in reducing populations of this important
parasitoid species in caneberry during the summer.
No attempt was made in our study to correlate spray practices or host densities with levels of
parasitism or the presence of individual species. However, these relations are of importance in
more fully assessing the role of parasitoids in management of orange tortrix populations.
Further investigations should determine the effects of early season insecticide applications,
cultural practices, and surrounding habitat on the performance of these species.
REFERENCES CITED
AliNiazee, M. T. 1980. Filbert insect and mite pests. Oregon State Agric. Exp. Sta. Bull. 643. 13pp.
Anonymous. 1926. Entomological work of the year. Rep. Calif. Agric. Expt. Sta. 1924-25. Berkeley Calif. pp.
43-46 and 51-53.
Basinger, A. J. 1935. Parasites reared from Argyrotaenia citrana. Calif. Agric. Mo. Bull. 24: 233-234.
Breakey, E. P. 1951. Natural control of the orange tortrix in western Washington. J. Econ. Entomol. 44: 424.
Breakey, E. P. and G. S. Batchelor. 1948. The orange tortrix, a pest of raspberries in western Washington. J. Econ.
Entomol. 41: 805-806.
Coop, L. 1983. Orange tortrix parasitoid complex and thermal constants for egg hatch. MS thesis. Oregon State
Univ., Corvallis.
Kido, H., D. L. Flaherty, C. E. Kennett, N. F McCalley, and D. F. Bosch. 1981. Seeking the reasons for differences
in orange tortrix infestations. Calif. Agric. 34: 27-29.
Kieffer, J. N., C. H. Shanks, and W. J. Tumer. 1983. Populations and control of insects and spiders contaminating
mechanically harvested red raspberries in Washington and Oregon. J. Econ. Entomol. 76: 649-653.
Knight, A. L. and B. A. Croft. 1986. Larval survivorship of Argyrotaenia citrana (Lepidoptera: Tortricidae)
overwintering on small fruits in the Pacific Northwest. J. Econ. Entomol. 79: 1524-1529.
Knight, A. L. and B. A. Croft. 1987a. Immature developmental requirements and factors influencing spring
emergence of Argyrotaenia citrana (Lepidoptera: Tortricidae) on caneberries, Rubus spp. in the Pacific
Northwest. J. Econ. Entomol. 80: 799-805.
Knight, A. L. and B. A. Croft. 1987b. Regional population dynamics and seasonal spatial patterns of Argyrotaenia
citrana (Lepidoptera: Tortricidae) as measured by a pheromone trap grid and larval sampling. Environ.
Entomol. 16: 59-67.
Knight, A. L., R. LaLone, G. Fisher, and L. Coop. 1988. Management of leafrollers on caneberries in the Pacific
Northwest. Oregon State Univ. Ext. Circ. 1263. 8pp.
Krombein, K. V., P. D. Hurd, Jr., D. R. Smith, and B. D. Burks. 1979. Catalog of Hymenoptera in America north of
Mexico. Vols., 1 and 3. Smithsonian Inst. Press, Washington, DC.
LaLone R. S. 1980. Pest management of leafrollers in caneberries grown in Oregon. Acta Hort. 112: 135-141.
Lyon, R. L., C. E. Richmond, J. L. Robertson, and B. A. Lucas. 1972. Rearing diapause and diapause-free western
spruce budworm (Choristoneura occidentalis) (Lepidoptera: Tortricidae) on an artificial diet. Can. Entomol.
87: 178-187.
Madsen, H. F. and L. B. McNelly. 1961. Important pests of apricots. Calif. Agric. Exp. Sta. Bull. 783. 40 pp.
Powell, J. A. 1964. Biological and taxonomic studies on tortricine moths, with reference to the species in
California. Univ. of Calif. Pubs. in Entomol. Vol. 32. Univ. Calif. Press Berkeley. 317 pp.
Rosenstiel, R. G. 1949. Life history and control of the orange tortrix in Oregon. J. Econ. Entomol. 42: 37-40.
Schwartz, J. L. and R. L. Lyon. 1970. Laboratory culture of orange tortrix, and its susceptibility to four
insecticides. J. Econ. Entomol.63:1788-1790.
66 J. ENToMoL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
PSEUDODIPHASCON ARROWSMITHI, A NEW SPECIES OF TARDIGRADE
FROM BRITISH COLUMBIA, CANADA (MACROBIOTIDAE:
EUTARDIGRADA: TARDIGRADA)
R. D. KATHMAN
DEPARTMENT OF BIOLOGY
UNIVERSITY OF VICTORIA
P.O. Box 1700
VicTorIiA, B. C. V8W 2Y2
CANADA
D. R. NELSON
DEPARTMENT OF BIOLOGICAL SCIENCES
EAST TENNESSEE STATE UNIVERSITY
JOHNSON City, TENNESSEE 37614
USA
ABSTRACT
A new species of macrobiotid tardigrade was found on two mountains on Vancouver
Island, British Columbia, during a study of the tardigrades on five mountains on the
island. Pseudodiphascon arrowsmithi, n. sp., is distinguished from other species in the
genus by its three large macroplacoids with the third as long as or longer than the first,
the very large microplacoid and the presence of lunules.
INTRODUCTION
Because the literature dealing with tardigrades in Canada, and particularly in British
Columbia, is very sparse, a survey of tardigrades on Vancouver Island was undertaken to
document their presence and to compare it with the only two previous publications on
tardigrades from B. C. (Richters, 1908; Murray, 1910). Three other publications (Mathews,
1938; Baumann, 1960; Schuster and Grigarick, 1965) listing tardigrades from B. C. merely
reiterate the species found by Richters and Murray.
MATERIALS AND METHODS
A total of 41 specimens of Pseudodiphascon arrowsmithi, n. sp., were collected on two
mountains on Vancouver Island (Fig. 1): 14 were collected at 760 m elevation on Green
Mountain in the moss Dicranum fuscescens on 17 July 1986, and 27 on Mt. Arrowsmith--26
on 09 July 1986 at 760 m in three species of mosses, D. fuscescens, Claopodium bolanderi and
Mnium spinulosum, and one individual on 10 July 1987 at 1370 m in D. fuscescens.
The samples of moss were placed in paper bags and air-dried for several months. Each
sample was then removed from the bag, placed in a stoppered funnel and allowed to soak in
water for eight hours, after which the moss was removed and shaken in a separate container of
water several times. The water and its contents were poured into a 45 {4m mesh sieve to retain
the tardigrades, which were placed in a gridded petri dish and extracted using a stereomicro-
scope. Each tardigrade was placed in Hoyer’s mounting medium on a microscope slide and
sealed with a cover slip. After complete drying of the mountant the cover slip was ringed with
nail polish to prevent further air penetration.
Identifications were made using a phase-contrast compound microscope with oil immer-
sion. All measurements were made using a calibrated eyepiece micrometer. Buccal tube
length was considered the distance between the anterior end of the buccal tube excluding the
mouth ring and the beginning of the spiralling; pharyngeal tube length was the distance from
the beginning of the spiralling to the pharyngeal apophyses; and total length of the tardigrade
was the distance from the anterior end of the head to the junction of the fourth pair of legs. The
drawings were made with a drawing tube attached to the compound microscope.
J. Enromot Soc. Brit. COLUMBIA 86 (1989), SEpr. 30, 1989 67
Vancouver
Island
CANADA
Figure 1. Location of sampling areas on Vancouver Island, British Columbia, Canada. AS = Mt.
Arrowsmith, GR = Green Mountain.
TAXONOMIC ACCOUNT
Eutardigrada Marcus, 1927
Macrobiotidae Thulin, 1928
Pseudodiphascon Ramazzotti, 1964
Pseudodiphascon arrowsmithi, n. sp.
(Fig. 2)
Description. Holotype. Total length 430 um; colorless; cuticle smooth; eyes absent (Fig.
2A). Ten buccal lamellae present. Mouth ring with crests and distinct dentation, rectangular-
shaped. Buccal tube with ventral tube support, extended almost to stylet support insertions;
buccal tube length 26 um, width 4.4 im. Pharyngeal tube walls thickened, spiralled and
flexible; length 19 um, width 4.4 lum; pharyngeal tube with evident spiralling starts imme-
diately below stylet support insertions. Pharyngeal bulb large and round. Pharyngeal
apophyses large; 3 macroplacoids, the first 5.5 um long, second 3.1 [tm and third 5.5, third
with inward-projecting enlargement at posterior end; microplacoid large, 3.1 tum (Fig. 2B).
All legs small, with fourth pair slightly smaller than the first 3 pairs. Claw sequence 2112;
claws on 4th pair of legs larger than on first 3 pairs; primary branch of internal and external
claws with 2 accessory points; lunules present but small, more evident on claws of 4th leg
(Figs. 2C, 2D). Collected at 760 m on Green Mountain in the moss D. fuscescens, 17 July
1986. USNM #235439.
Paratypes. Total lengths 206-515 um. Buccal tube lengths 16-27 tm, widths 2.0-4.4 um;
pharyngeal tube lengths 11-19 um, widths 2.0-4.4 tum. First macroplacoid lengths 1.9-5.5 Um;
second 1.3-4.4 um; third 2.5-6.3 um; the third is usually as long as or longer than the first;
microplacoid 1.3-3.8 um. USNM #235437, 235438, 2 specimens; Dastych collection, 1
specimen; Kristensen collection, 1 specimen; Nelson collection, 2 specimens; Kathman
collection, 34 specimens; all from Mt. Arrowsmith or Green Mountain on Vancouver Island.
68 J. EnTomMoL Soc. Brit. CoLuMBIA 86 (1989), SzpT. 30, 1989
Figure 2. Pseudodiphascon arrowsmithi. A, Whole animal, ventral view; B, Buccopharyngeal apparatus;
C, Claws, 2nd pair of legs; D, Claws, 4th pair of legs; E, Profile of macroplacoids, a = arrowsmithi, b =
bindae. Scale bars in um as follows: A, 20; B, 6.3; C-D, 4.8; E, no scale.
J. ENToMo Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 69
Type locality. Northwest slope of Mt. Arrowsmith at 760 and 1370 m and southwest aspect
of Green Mountain at 760 m, both on Vancouver Island, British Columbia, Canada.
Etymology. Named after Mt. Arrowsmith, one of the mountains on which it was collected.
Although the International Commission of Zoological Nomenclature recommends the “ensis”’
or “‘iensis” ending for geographical locations, the alternative procedure (Appendix D, Section
IV, 22b) of using the masculine noun in the genitive case is adopted here as it is more
euphonious.
DISCUSSION
Three of the four known species of Pseudodiphascon have been tentatively placed in this
genus despite incomplete descriptions or lack of specimens to allow sufficient detail of
important morphological characters. The original descriptions do not mention a spiralled
flexible pharyngeal tube nor a ventral tube support in the buccal tube for P. diphasconoide
Tharos, 1969, P. inflexum Arcidiacono, 1964, and P. dubius Schuster and Toftner, 1982. P.
diphasconoide appears to be a much smaller tardigrade, with a thinner and shorter buc-
copharyngeal tube than P. arrowsmithi. P. diphasconoide has 2 small round macroplacoids,
with the first a little longer than the second, and no microplacoid. This species was found only
in Viemam. The total length of P. inflexum coincides with that of P. arrowsmithi, but the
buccopharyngeal tube is much narrower in P. inflexum. P. inflexum has 2 macroplacoids, the
first longer than the second, and a very small microplacoid. The dentate lunule in P. inflexum
is very large with 8-12 teeth, whereas in P. arrowsmithi it is very small with no discernable
dentation. P. inflexum has been collected only in Sicily. P. dubius is a small tardigrade (length
240 wm) with a thin, short buccopharyngeal tube (length 31 tm). There are 3 small
macroplacoids, all equal in length (1.5 um) and a minute microplacoid. This species has only
been reported from the Dominican Republic. P. bindae Christenberry and Higgins, 1979,
collected in Alabama, USA, is the species most closely related to P. arrowsmithi. The largest
specimen found was 437 um (cf. 515 um for P. arrowsmithi). Christenberry and Higgins
(1979) stated that the 10 buccal lamellae could only be seen using SEM; in P. arrowsmithi they
are evident with a phase microscope. Eyes are absent in P. arrowsmithi and present in P.
bindae. There is no evident dentation above the crests in P. bindae. The buccal and
pharyngeal tubes are longer in P. bindae (27-44 um; 16-35 tm, respectively) than in P.
arrowsmithi (16-27 um; 11-19 tum, respectively); combined length for P. bindae is 43-79 um,
whereas for P. arrowsmithi it is 29-45 um. The width of the buccopharyngeal tube for P.
bindae and P. arrowsmithi is about the same (2.4-4.0 um, 2.0-4.4 tum, respectively), but the
ratio of width to length for P. bindae is much larger. The spiralling in P. arrowsmithi starts
immediately below the insertion of the stylet supports and is a tight, dense type of spiralling,
often difficult to see, whereas in P. bindae it begins well below the stylet support insertions and
is a large, loose type of spiralling, easily seen. In P. bindae the first macroplacoid is always the
longest and the second is the shortest, with the microplacoid slightly shorter than the second
macroplacoid. In profile the macroplacoids of P. arrowsmithi are always smooth-edged,
whereas in P. bindae they are rough (Fig. 1E). In P. arrowsmithi the third macroplacoid is
equal to or longer than the first, and in some cases the second is only slightly shorter than the
first. The microplacoid is very large, often equal to or larger than the second macroplacoid.
Lunules are absent on P. bindae and present on P. arrowsmithi.
It appears that P. arrowsmithi could be classified as one of Ramazzotti and Maucci’s (1983)
montane or alpine species, since it was collected only at 760 m or higher on Vancouver Island,
despite many samples of the same moss species being collected at several lower elevations,
down to sea level. The two mountains on which it was found are approximately 26 km apart.
ACKNOWLEDGMENTS
We wish to thank R. O. Schuster for loan of P. bindae and P. dubius; L.H. Howard and R.
E. Woods for assistance with the collections of mosses; and Crown Forest and MacMillan-
Bloedel for access to the two mountains. Professor W. B. Schofield of the University of B. C.
70 J. ENToMot Soc. Brrr. COLUMBIA 86 (1989), SEPT. 30, 1989
verified the species of mosses. This project was partially funded by a British Columbia
Graduate Research Engineering and Technology Award in conjunction with E.V.S. Consul-
tants to the senior author.
LITERATURE CITED
Baumann, H. 1960. Beitrag zur Kenntnis der Tardigraden in Nord-Amerika. Zool. Anz. 165:123-128.
Christenberry, D. and R. P. Higgins. 1979. A new species of Pseudodiphascon (Tardigrada) from Alabama.
Trans. Amer. Microsc. Soc. 98:508-514.
Mathews, G. B. 1938. Tardigrada from North America. Amer. Midl. Nat. 19:619-627.
Murray, J. 1910. Canadian Tardigrada. Pp. 159-178 in Report for the Scientific Investigation of the British
Antarctic Expedition 1907-1909, vol. 1, London.
Ramazzotti, G. and W. Maucci. 1983. Il phylum Tardigrada. Mem. Ist. Ital. Idrobiol. 41:1-1012.
Richters, F. 1908. Beitrag zur Kenntnis der Moosfauna Australiens und der Inseln des Pazifischen Ozeans. Zool.
Jahrb. Abt. Syst. Oekol Geogr. Tiere 26:196-213.
Schuster, R. O. and A. A. Grigarick. 1965. Tardigrada from western North America with emphasis on the fauna of
California. Univ. Calif. Publ. Zool. 76:1-67.
NEW AND LITTLE KNOWN SCALE INSECTS (HOMOPTERA: COCCOIDEA)
FROM BRITISH COLUMBIA
F. KozAr!, L.M. HumMBLgE2, R.G. Foottir? AND I.S. Orvos2
1 PLANT PROTECTION INSTITUTE,
HUNGARIAN ACADEMY OF SCIENCES, H-1525 BUDAPEST, P.O. Box 102, HUNGARY
2 FORESTRY CANADA, PACIFIC AND YUKON REGION,
506 West BURNSIDE ROAD, VicroriA, B.C., V8Z 1M5, CANADA
3 BIOSYSTEMATICS RESEARCH CENTRE, AGRICULTURE CANADA,
K.W. NEATBY BLDG., C.E.F., OTTAWA, ONTARIO K1A 0C6, CANADA
ABSTRACT
Thirty-six species of scale insects (Coccoidea) belonging to 6 families were recov-
ered during a recent collecting trip in British Columbia. Of these, 16 species (Orthezia
newcomeri, Anisococcus oregonensis, Heterococcus nudus, Phenacoccus capensis,
Phenacoccus colemani, Phenacoccus solani, Spilococcus geraniae, Spilococcus keiferi,
Tridiscus sp., Trionymus caricis, Trionymus utahensis, Acanthococcus greeni, Phy-
sokermes concolor, Physokermes hemicryphus, Physokermes taxifoliae, Stramenaspis
kelloggi) are new records for Canada and 26 new for British Columbia. The latter now
has 42 species. The level of infestation, phenological stage, host plant data (including
several new associations) and the localities of collections are also presented.
Résumé
Lors d’un récent voyage de cueillette effectué en Columbie-Britannique, on a
rapporté trente-six espéces de cochenilles (Coccoidea) appartenant 4 6 familles. Seize
de ces espéces (Orthezia newcomeri, Anisococcus oregonensis, Heterococcus nudus,
Phenacoccus capensis, Phenacoccus colemani, Phenacoccus solani, Spilococcus gera-
niae, Spilococcus keiferi, Tridiscus sp., Trionymus caricis, Trionymus utahensis, Aca-
nthococcus greeni, Physokermes concolor, Physokermes hemicryphus, Physokermes
taxifoliae, Stramenaspis kelloggi) sont de nouveaux records pour le Canada, et 26
d’entre elles sont nouvelles en Colombie-Britannique, qui compte maintenant 42
espéces. Le rapport traite du degré d’infestation et du stade phénologique; il fournit
également des données sur les plantes hétes (y compris plusieurs nouvelles associa-
tions) et sur les localités ot: a eu lieu la cueillette.
INTRODUCTION
The scale insect fauna of Canada is poorly known. Scudder (1979) noted that 56 species
have been recorded from Canada. No comprehensive work exists for the Coccoidea of Canada,
however, Foottit and Williams (pers. comm.) have prepared a list of the scale insect species in
the slide holdings of the Canadian National Collection.
J. ENromot Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 71
Venables (1939) published a preliminary checklist of scale insects of British Columbia,
listing 14 species, primarily from the Okanagan Valley and Vancouver areas. Limited
additional records (host associations, localities) for the province can be found in the taxonomic
works of Ferris (1937-1955) and Richards (1958) and in the applied entomological literature
(Downing et al. 1956; Glendenning 1925; Evans 1982, 1983; Furniss and Carolin 1977;
Hopping 1937; Kondo and Moody 1986; Madsen and Morgan 1975; Rubin and Beirne 1975;
Waddell 1952). Our paper presents the results of brief collecting trips in the vicinity of
Penticton (late June), and Vancouver and Victoria (early July), British Columbia during 1988.
It is hoped that the records presented here will stimulate additional studies of the Coccoidea in
British Columbia and Canada.
Microscope slides of the species collected are deposited in the collection of the Plant
Protection Institute, Hungarian Academy of Sciences (Budapest, Hungary), with duplicates
deposited in the collection of the Pacific Forestry Centre (PFC), Forestry Canada (Victoria,
B.C.). As well, for those host plants indicated by an ‘*’, dry plant material with scale insects is
deposited in the PFC reference collection.
RESULTS
A total of 36 species of scale insects belonging to 6 families, was collected in British
Columbia in late June and early July, 1988. The species collected are listed by family. Data for
each species are given in the following order: scientific name, geographic location and date of
collection, (day, month, year), place (niche) of collection, sex and developmental stage(s) of
scales, level of infestation, and identification number (in parentheses) of slides in the
collection of the senior author. Forest Insect and Disease Survey (FIDS) registration numbers
are provided for specimens originating from the PFC reference collection. Additional informa-
tion such as taxonomic characters and geographic distribution is presented for some species.
Those species which represent new records for the Canadian fauna are marked with an X and
those new for British Columbia are marked with an O before the scientific name. Names of
native species of host plants conform to those of Scoggan (1978a,b, 1979). The level of
infestation is marked as F (frequency) (on a scale of 0 to 4) (Kozér and Viktorin 1979). All
collection data without special reference are those of the senior author, assisted in some cases
by L.M. Humble.
I. Ortheziidae
1. O Arctorthezia occidentalis Douglas, 1891. Furry Creek, 5 km S of Britannia, 07.07,1988,
among mosses, females, nymphs, F=1 (3307); Victoria (Highland Rd.), 12.07,1988, between
mosses*, female, first instar nymphs, eggs, F=2 (3330). While this species normally has
8-segmented antennae, all females from our collections have 7-segmented antennae. Morrison
(1952) also reported one specimen with 7-segmented antennae. This variation needs further
Study, as it may indicate that A. occidentalis, as currently understood, includes some
undescribed species. This species is widely distributed from California to Alaska, including
the Vancouver area (Morrison 1925, 1952).
2. O X Orthezia newcomeri Morrison, 1952. Summerland, 30.06,1988, Artemisia frigida
Willd. (Compositae), on the leaves, female, first instar nymphs, F=1 (3278). This species was
previously recorded on Penstemon (Scrophulariaceae) from Yakima County, WA, USA
(Morrison 1952).
II. Pseudococcidae
3. O X Anisococcus oregonensis Ferris, 1950. Summerland, 30.06,1988, Antennaria par-
vifolia Nutt. (Compositae), on leaves, females, F=1 (3289). Our specimens differ from the
1Z J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
original description (Ferris 1950) in that the antennae are 9-segmented instead of 8, the
ostioles are hardly noticeable, and there are some differences evident in the structure of the
frontal cerarii. It will be necessary to collect additional material to determine the significance
of this variation. Until now this species was known only from California and Washington
(USA) on Eriogonum umbellatum Torr. (Polygonaceae) (McKenzie 1967).
4. O X Heterococcus nudus (Green, 1926). Summerland, 30.06,1988, Haplopappus sp.
(Compositae), on roots, female, F=1 (3281); Langford (Savory Rd.), 12.07,1988, Agropyron
sp. (Gramineae), in leaf sheaths, females (yellowish), first instar nymphs, eggs, F=2 (3344).
This species is widely distributed in Palearctic and Nearctic regions. In the United States it is
known also from Yakima, WA (Miller 1975).
5. Phenacoccus aceris (Signoret, 1875). Victoria (urban), 10.07,1988, Ulmus sp. (Ulmaceae),
dead females, eggs, F=1 (3313); Victoria (urban), 10.07,1988, Acer sp. (Aceraceae), dead
females, eggs, F=2 (3314); Victoria (urban), 10.07,1988, Prunus sp. (Rosaceae), dead females,
F=2 (3321). This species is a widely distributed pest in the Holarctic Region (Kosztarab and
Kozar 1988), and is well known in Canada (Ferris 1950).
6. O X Phenacoccus capensis Ferris, 1950. Hwy. 99, 17 km N of Brackendale, 07.07,1988,
Spiraea douglasii Hook. (Rosaceae), on roots, females, F=1 (3302). Our specimens differ
from the original description by having fewer thin tubular ducts ventrally and more thick
tubular ducts dorsally. Based on these characters, our specimens resemble P. colemani;
however, the latter lacks the cerarian-like structure on its dorsum. Until now this species was
known only from Mexico on Phyllanthus (Euphorbiaceae) (Ferris 1950).
7.O X Phenacoccus colemani Ehrhorn, 1906. Furry Creek, 5 km S of Britannia, 07.07,1988,
Holodiscus discolor (Pursh) Maxim. (Rosaceae), on twig, female, F=1 (3311). This species
was previously known only from the southern part of the Nearctic Region on Arctium and
Encelia (Compositae), Arctostaphylos (Ericaceae), Eriogonum (Polygonaceae), Garrya (Gar-
ryaceae), Lantana (Verbenaceae), Mahonia (Berberidaceae), Castilleia and Pedicularis
(Scrophulariaceae), Phacelia (Hydrophyllaceae), Rubus (Rosaceae), and Symphoricarpos
(Caprifoliaceae) (Ferris 1950; McKenzie 1967).
8.O X Phenacoccus solani Ferris, 1918. Summerland, 30.06,1988, Haplopappus sp., on roots,
female, F=1 (3281); Summerland, 30.06,1988, Centaurea diffusa Lam. (Compositae), on
roots, female, F=1 (3288). This species is widely distributed in the Nearctic Region
(McKenzie 1967) and in other parts of the world (Williams, Blair and Khasimuddin 1985).
9. O Pseudococcus affinis (Maskell, 1894) [=obscurus Essig, 1909]. Victoria (indoor),
13.07,1988, Amaryllis sp. (Amaryllidaceae), females, nymphs and eggs, F=3 (3350). A
cosmopolitan pest species, found on a wide variety of unrelated hosts. In the northern parts of
the temperate zone it is found only in greenhouses (Cox 1987; Furniss and Carolin 1977;
McKenzie 1967).
10. O X Spilococcus geraniae (Rau, 1938). Hwy. 99, 17 km N of Brackendale, 07.07,1988,
Gaultheria shallon Pursh. (Ericaceae), on roots, females (greenish), nymphs and eggs, F=2
(3303). This species was previously known only from New York and California on Geranium
robertianum L. (Geraniaceae) and Artemisia douglasiana Bess. (Compositae), respectively
(McKenzie 1967).
11. O X Spilococcus keiferi McKenzie, 1960. Summerland, 30.06,1988, Haplopappus sp., on
roots, females, F=2 (3281); Summerland, 30.06,1988, Antennaria parvifolia, on roots,
females, F=1 (3289). This species is known from California and Washington on Ambrosia and
Franseria (Compositae) and various Gramineae (McKenzie 1967).
12. O X Tridiscus sp. Victoria (sea coast), 10.07,1988, Agropyron sp.*, in leaf sheaths, female,
eggs, F=2 (3320). This is a new species and will be described elsewhere (Kozar and Foottit,
pers. comm.).
J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 73
13. O X Trionymus caricis McConnell, 1941. Langford (Savory Rd), 12.07,1988, Elymus cf.
innovatus Beal (Gramineae) and Vulpia microstachys (Nutt.) Munro* (Gramineae), in leaf
sheaths, females (lilac), eggs, F=1 (3345). This species is almost identical to the Palearctic T.
radicum (Newstead, 1895). T. caricis was previously known only from the USA (California,
Maryland and Tennessee) on Carex (Cyperaceae) and Elymus and Uniola spp. (Gramineae)
(McKenzie, 1967).
14. O X Trionymus utahensis (Cockerell, 1916). Summerland, 30.06,1988, Elymus piperi
Bowden (Gramineae), in leaf sheaths, females, eggs, first instar nymphs, F=1 (3292);
Langford (Savory Rd.), 12.07,1988, Agropyron sp., in leaf sheaths, females (lilac), eggs, first
instar nymphs, F=1 (3344). Previously, this species was known only from the USA on various
grasses (McKenzie 1967).
III. Eriococcidae
15. O X Acanthococcus greeni (Newstead, 1898). Summerland, 30.06,1988, Agropyron
intermedium (Host) Beauv.* (Gramineae), on leaves, females, eggs, F=3 (3283); Summerland,
30.06,1988, Festuca ovina L.* (Gramineae), on leaves, females, F=1 (3286). The specimens
agree with the descriptions of A. greeni given by Williams (1985). It is a common grass-
inhabiting species occuring throughout the Palearctic including the Far East and Siberia in the
U.S.S.R. (Danzig, 1980). Some morphological similarities to A. bahiae (Ehrhorn) were also
evident; however, the latter species has been found only on the roots of Bahia sp. (Compositae)
from California (Ferris 1950). Because of the incomplete knowledge of the Eriococcidae in
North America, the taxonomic status of the species is questionable.
16. O Gossyparia spuria (Modeer, 1778). Summerland, 30.06,1988, Ulmus sp.*, females F=3
(3282); Vancouver (UBC), 07.07,1988, Alnus crispa ssp. sinuata (Regel) Hult.* (Betulaceae),
females, first instar nymphs, F=2 (3298). A common pest of Ulmus in the Holarctic Region,
including Canada (Kosztarab and Kozar 1988; Furniss and Carolin 1977).
IV. Coccidae
17. O Chloropulvinaria (Pulvinaria) floccifera (Westwood, 1870). Vancouver (UBC),
07.07,1988, Prunus laurocerasus L.* (Rosaceae), on leaves, females, eggs, first instar
nymphs, F=3 (3299). A cosmopolitan pest, previously known from Canada (Furniss and
Carolin 1977; Hamon and Williams 1984).
18. O Coccus hesperidum (Linnaeus, 1758). Victoria (indoor), 13.07,1988, Citrus sp.*
(Rutaceae), females and nymphs, F=3 (3349). A common cosmopolitan pest, also well known
in Canada. In northern regions found in greenhouses only (Hamon and Williams 1984).
19, Eulecanium tiliae (Linnaeus, 1758). Vancouver (Stanley Park), 01.07,1988, Rosa sp.*
(Rosaceae) and Acer sp., dead females and male test, F=3 (3294, 3295); Vancouver (Stanley
Park), 01.07,1988, Vaccinium sp. (Ericaceae), dead females, F=1 (3296); Vancouver (UBC),
07.07,1988, Alnus crispa ssp. sinuata*, dead females, male tests, second instar nymphs, F=3
(3298); Furry Creek, 5 km S of Britannia, 07.07,1988, Holodiscus discolor, dead females,
male tests, F=1 (3311); Furry Creek, 5 km S of Britannia, 07.07,1988, Alnus rubra Bong.*
(Betulaceae), female, male, first instar nymphs, F=1 (3312); Victoria (urban), 10.07,1988,
Ulmus sp., dead females, male tests; F=3 (3313); Victoria (urban), 10.07,1988, Malus pumila
Mill. (Rosaceae), dead females, male tests, F=1 (3319); Victoria (urban), 10.07,1988, Prunus
domestica L. (Rosaceae), dead females, male tests, F=1 (3319); Victoria (urban), 10.07,1988,
Prunus domestica, dead females, male tests, F=3 (3321); Victoria (PFC), 11.07,1988, Cra-
taegus monogyna Jacq.* (Rosaceae), female, male, F=1 (3325); Duncan (Chesterfield Rd.),
12.07,1988, Sorbus sp.* (Rosaceae), dead females, F=1 (3340); Duncan (Koksilah),
12.07,1988, Betula papyrifera Marsh.* (Betulaceae) and Acer campestre L.* (Aceraceae),
dead females, first instar nymphs, F=1 (3341, 3343); Langford (Savory Rd.), 12.07,1988, Salix
sp.* (Salicaceae), dead females, male tests, first instar nymphs, F=1 (3346). A common
cosmopolitan pest, well known in Canada (Kosztarab and Kozér 1988).
74 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), Sept. 30, 1989
20. O Neopulvinaria (Pulvinaria) innumerabilis (Rathvon, 1854). Summerland, 30.06,1988,
Spiraea sp., dead females, F=1 (3275). Widely distributed in the USA and Canada (Gill 1988;
Furniss and Carolin 1977).
21. Parthenolecanium corni (Bouché, 1844). Summerland, 30.07,1988, Cornus sp. (Com-
aceae), dead females, F=1 (3273); Summerland, 30.06,1988, Spiraea sp., dead females, first
instar nymphs, F=1 (3275); Summerland, 30.06, 1988, Rosa acicularis Lindl. (Rosaceae), dead
females, F=1 (3275); Victoria (Highland Rd.), 12.07,1988, Acer sp., dead female, male tests,
F=1 (3329). A common pest in the northern hemisphere, including Canada (Furniss and
Carolin 1977; Kosztarab and Kozar 1988).
22. O Parthenolecanium pruinosum (Coquillett, 1891). Victoria, 13.07,1964, Veronica sp.
(Scrophulariaceae), from the collection of the Pacific Forestry Centre, FIDS 64.1570.01,
(3350). A common pest in North America, including Canada (Gill 1988).
23. O Parthenolecanium quercifex (Fitch, 1859). Duncan (Koksilah), 12.07,1988, Quercus
coccinea Muenchh. (Fagaceae), females, F=2 (3343). This species is morphologically identi-
cal with the European species, P. rufulum (Cockerell, 1903), but the question of synonomy will
require study of the types.
24. O X Physokermes concalor Coleman, 1903. Tofino, 12.06,1987, Picea sitchensis (Bong.)
Carr. (Pinaceae), females, eggs, first instar nymphs, from the PFC reference collection, FIDS
87.349.01, (3350a). This species was identified on the basis of post reproductive females only.
There were also several first instar nymphs on the needles and in the female bodies which
showed extreme morphological variability. Additional study of young females and first and
second instar nymphs of both sexes is needed to determine the range of natural variation of
these characters. The species was previously known only from California on Abies concolor
Hoopes (Pinaceae) (Gill 1988).
25. O X Physokermes hemicryphus (Dalman, 1826). Vancouver (Stanley Park), 01.07,1988,
Picea abies Karst. (Pinaceae), dead females, eggs, first instar nymphs, F=1 (3293); Vancouver
(UBC), 07.07,1988, Picea glauca (Moench) Voss*, dead females, first instar nymphs, F=2
(3301); Victoria (PFC), 11.07,1988, Picea engelmannii Engelm.*, females, eggs, first instar
nymphs, F=1 (3324); Duncan (Chesterfield Rd.), 12.07,1988, Picea abies*, dead females, first
instar nymphs, F=3 (3338); Summerland, 07.06,1982, Picea glauca*, females, from the PFC
reference collection, FIDS 82.0115.01, (3351). The latter material needs further study,
especially of the first and second instar nymphs, which are the most useful stages for the
identification of species of Physokermes. Until recently most collections of Physokermes in
the USA and Canada were identified as Physokermes piceae (Schrank) (Gill 1988; Kondo and
Moody 1986). Most identifiable lots of Physokermes on spruce in the United States have now
been shown to be the similar Palearctic species, P. hemicryphus, not P. piceae (Gill 1988). The
same may also be true for Canada, but will require additional collection and study.
26. O X Physokermes taxifoliae Coleman, 1903. Duncan (Chesterfield Rd.), 12.07,1988,
Pseudotsuga menziesii (Mirb.) Franco (Pinaceae), females, eggs, first instar nymphs, F=1
(3334). Well known in California and Oregon (Gill 1988). The first instar nymphs of P.
taxifoliae are very similar to those of P. fasciatus Borchsenius from U.S.S.R. (Central Asia)
and P. inopinatus Danzig and Kozar from Hungary. However, there are some differences in the
female morphology which require further study.
V. Asterolecaniidae
27. Asterodiaspis variolosa (Ratzeburg, 1870), Victoria (urban), 10.07,1988, Quercus sp.*
(Fagaceae), females, eggs, nymphs, F=3 (3315); Langford (Savory Rd.), 12.07,1988, Quercus
garryana Dougl.*, dead females, eggs, first and second instar nymphs, F=1 (3348). Widely
distributed in the USA and Canada (Ferris 1955).
J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 i
VI. Diaspididae
28. Carulaspis juniperi (Bouché, 1851). Summerland, 30.06, 1988, Thuja plicata Donn*
(Pinaceae), females, eggs, F=2 (3280); Victoria (PFC), 11.07,1988, Juniperus communis L.*
(Pinaceae), females, eggs, first instar nymphs, F=3 (3328); Duncan (Chesterfield Rd.),
12.07,1988. Chamaecyparis nootkatensis (D. Don) Spach* (Pinaceae), females, eggs, first
instar nymphs, F=4 (3336). A cosmopolitan pest, widely distributed in North America
(Borchsenius 1966; Furniss and Carolin 1977). In early North American literature this species
was sometimes referred to as Carulaspis visci (Schrank) (Ferris 1937).
29. Chionaspis pinifoliae (Fitch, 1856). Summerland, 30.06,1988, Pinus ponderosa Laws.*
(Pinaceae), second instar nymphs, F=3 (3279); Vancouver (UBC), 07.07,1988, Pinus prob.
contorta Dougl. ex Loudon*, dead females, eggs, first instar nymphs, F=3 (3300); Victoria
(urban), 10.07,1988, Pinus sp., dead females, F=1 (3316); Victoria (PFC), 11.07,1988, Pinus
sp. and Pseudotsuga menziesii, females, F=1 (3322, 3323); Victoria (PFC), 11.07,1988, Picea
engelmannii, females, F=1 (3324); Victoria (PFC), 11.07,1988, Pinus ponderosa, females,
eggs, F=2 (3326); Duncan (Chesterfield Rd), 12.07,1988, Pseudotsuga menziesii, females,
F=1 (3334); Duncan (Chesterfield Rd.), 12.07,1988, Pinus mugho Turra*, females, eggs, F=2
(3335); Duncan (Chesterfield Rd.), 12.07,1988, Pinus sp., dead females, F=1 (3337). A widely
distributed pest in North America (Borchsenius 1966; Furniss and Carolin 1977).
30. Lepidosaphes ulmi (Linnaeus, 1758). Summerland, 30.06,1988, Cornus sp., dead females,
F=1 (3273); Summerland, 30.06,1988, Populus balsamifera L.* (Salicaceae), dead females,
first instar nymphs, F=3 (3274); Summerland, 30.06,1988, Rosa acicularis*, dead females,
first instar nymphs, F=3 (3276); Summerland, 30.06,1988, Malus pumila, dead females, first
instar nymphs, F=3 (3277); Summerland, 30.06,1988, Ribes cereum Doug]. (Saxifragaceae),
dead females, first instar nymphs, F=4 (3284); Furry Creek, 5 km S of Britannia, 07.07,1988,
Salix sitchensis Sanson* (Salicaceae), dead females, first instar nymphs, F=2 (3310); Furry
Creek, 5 km S of Britannia, 07.07,1988, Alnus rubra*, dead females, F=1 (3312); Victoria
(urban), 10.07,1988, Crataegus oxyacantha L.* (Rosaceae) and Malus pumila, dead females,
first instar nymphs, F=3 (3317, 3318); Langford (Savory Rd.), 12.07,1988, Holodiscus
discolor*, dead females, first instar nymphs, F=3 (3347). Widely distributed pest all over the
world (Kosztarab and Kozar 1988; Furniss and Carolin 1977).
31. Nuculaspis californica (Coleman, 1903). Summerland, 30.06,1988, Pinus ponderosa*,
females, F=3 (3279); Duncan (Chesterfield Rd), 12.07,1988, Picea abies, dead females, F=1
(3338); Summerland, 07.06,1982, Picea glauca from the PFC reference collection, FIDS
82.115.01, (3351). Widely distributed pest in North America (Borchsenius 1966; Furniss and
Carolin 1977).
32. O Quadraspidiotus gigas (Thiem and Germeck, 1934). Langford (Savory Rd.), 12.07,1988,
Salix sp.*, dead females, F=1 (3346). Widely distributed pest in the northern hemisphere
(Kosztarab and Kozar 1988), but its distribution in North America is not well known.
33. Quadraspidiotus ostreaeformis (Curtis, 1843). Duncan (Chesterfield Rd.), 12.07,1988,
Aesculus hippocastanum L. (Hippocastanaceae), dead females, F=1 (3339). Widely distrib-
uted pest all over the world (Kosztarab and Kozar 1988).
34. Quadraspidiotus perniciosus (Comstock, 1881). Summerland, 30.06,1988, Malus pumila,
females, first instar nymphs, F=4 (3277). Widely distributed pest all over the world (Kosztarab
and Kozdér 1988).
35. O Rhizaspidiotus dearnessi (Cockerell, 1898). Summerland, 30.06,1988, Erigeron fili-
folius Nutt.* (Compositae) and Artemisia frigida*, females, F=1 (3290, 3291). This species is
known only from Canada, USA and Mexico (Borchsenius 1966).
36. O X Stramenaspis kelloggi (Coleman, 1903). Victoria (PFC), Pinus sp., 11.07,1988,
females, F=1 (3323). This species was previously known only from the USA (Borchsenius
1966; Furniss and Carolin 1977).
76 J. ENToMoL Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
DISCUSSION
Our collection of scale insects in British Columbia yielded 36 species belonging to 6 families,
namely Ortheziidae (2), Pseudococcidae (12), Eriococcidae (2), Coccidae (11), Aster-
olecaniidae (1) and Diaspididae (8). Of the species collected, 16 proved to be new for the scale
insect fauna of Canada and 26 are new for British Columbia.
From a zoogeographical point of view the scale-insect fauna of British Columbia is very
heterogenous. Boreal or montane species such as Arctorthezia occidentalis, Heterococcus
nudus, and Acanthococcus greeni as well as thermophilous species such as Anisococcus
oregonensis, Phenacoccus capensis, Spilococcus geraniae or the subtropical Chloro-
pulvinaria floccifera are represented in the diverse habitats examined. Our limited collections
show that the British Columbia fauna seems to be rich in scale insects, and therefore, deserves
more intensive studies.
ACKNOWLEDGEMENT
The senior author wishes to express his gratitude to Dr. Nello P.D. Angerilli (Agriculture
Canada Research Station, Summerland, B.C.) for his help and hospitality. We would like to
thank: Dr. E.T. Oswald (Forestry Canada, PFC, Victoria, B.C.) for determining some of the
plants; Drs. L. Safranyik, T. Sahota and H. Moeck (Forestry Canada, PFC) for reviewing an
earlier draft of the manuscript; J. Drozdjak (Plant Protection Institute, Budapest) for the
microscopic slide mounting; and OTKA for the financial support (Grant No. 1334) to the
senior author.
LITERATURE CITED
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Leningrad, 449 pp.
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and Industrial Research, Wellington, New Zealand, 231 pp.
Danzig, E.M. 1980. [Coccoids of the Far East USSR. With a phylogenetic analysis of the coccoid fauna of the
world] (in Russian). Nauka, Leningrad. 367 pp.
Downing, R.S., C.V.G. Morgan and M.D. Proverbs. 1956. List of insects and mites attacking tree fruits in the
interior of British Columbia. Proc. Ent. Soc. Br. Columb. 52:34-35.
Evans, D. 1982. Pine shoot insects common in British Columbia. Can. For. Serv., Envir. Can., Inf.Rep. BC-X-233.
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1983. Annotated checklist of insects associated with native pines in British Columbia. Can. For. Serv.,
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Ferris, G.F. 1937. Atlas of the scale insects of North America. The Diaspididae. Stanford Univ. Press, Stanford
CA. Ser.I:1-136.
1938. Atlas of the scale insects of North America. The Diaspididae. Stanford Univ. Press, Stanford CA.
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_____ 1941. Atlas of the scale insects of North America. The Diaspididae. Stanford Univ. Press, Stanford CA.
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1942. Atlas of the scale insects of North America. The Diaspididae. Stanford Univ. Press, Stanford CA.
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_______—«1950. Atlas of the scale insects of North America. The Pseudococcidae. Stanford Univ. Press, Stanford
CA. Ser. V(Pt. I):1-278.
1953. Atlas of the scale insects of North America. The Pseudococcidae. Stanford Univ. Press, Stanford
CA. Ser. VI(Pt. I):279-506.
1955. Atlas of the scale insects of North America. The families Aclerdidae, Asterolecaniidae,
Conchaspididae, Dactylopiidae and Lacciferidae. Stanford Univ. Press, Stanford CA. Ser.VII:233 pp.
Furniss, R.L., and V.M. Carolin. 1977. Western Forest Insects. U.S. Dept. Agr., Forest Service. no. 1339. 654 pp.
Gill, R.J. 1988. The scale insects of California (Part 1). The soft scales (Homoptera: Coccoidea: Coccidae).
California Department of Food and Agriculture, Technical Series in Agricultural Biosystematics and Plant
Pathology, No. 1. 132 pp.
Glendenning, R. 1925. The Lecanium scale outbreak in Vancouver, B.C. Proc. Ent. Soc. Br. Columb. 22:21-26.
Hamon, A.B., and M.L. Williams. 1984. The soft scale insects of Florida (Homoptera: Coccoidea: Coccidae).
Florida Department of Agriculture and Consumer Services, 11, 194 pp.
Hopping, G.R. 1937. Insects (or near relatives) of economic importance recently noted in British Columbia. Proc.
Ent. Soc. Br. Columb. 33:46-47.
Kondo, E.S., and B.H. Moody. 1987. Forest insect and disease conditions in Canada 1986. Forest Insect and
Disease Survey Canadian Forestry Service Ottawa, 128 pp.
Kosztarab, M., and F. Koz4r. 1988. Scale insects of Central Europe. Akadémiai Kiadé Budapest, 456 pp.
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Kozar, F., and A. Viktorin. 1978. Survey of scale insect (Homoptera: Coccoidea) infestations in European
orchards. Changes in the scale infestation levels in Hungarian orchards between 1971 and 1976. Acta
Phytopathologica Academiae Scientiarium Hunganriae 13:391-402.
Madsen, B.J. and C.V.G. Morgan. 1975. Mites and insects collected from vineyards in the Okanagan and
Similkameen valleys, British Columbia. J. Entomol. Soc. Brit. Columb. 72:9-14.
McKenzie, H.L. 1967. Mealybugs of California. University of California Press, Berkeley and Los Angeles, 526
Miller, D.R. 1975. A revision of the genus Heterococcus Ferris with a diagnosis of Brevennia Goux (Homoptera:
Coccoidea: Pseudococcidae). U.S. Dept. Agr. Tech. Bull. 1497, 61 pp.
Morrison, H. 1925. Classification of scale insects of the subfamily Ortheziinae. Jour. Agr. Res. 30:97-154.
1952. Classification of the Ortheziidae. Supplement to “‘Classification of scale insects of the subfamily
Ortheziinae”. U.S. Dept. Agr. Tech. Bull. 1052, 80 pp.
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90:305-313.
Rubin, A.Y. and B.P. Beirne. 1975. The European fruit lecanium, Lecanium tiliae (L.) (Homptera:Coccidae), in
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NEW RECORDS OF SLENDER WINTER STONEFLIES
(PLECOPTERA: CAPNIIDAE) IN BRITISH COLUMBIA
S. G. CANNINGS
DEPARTMENT OF ZOOLOGY,
UNIVERSITY OF BRITISH COLUMBIA,
VANCOUVER, B. C. V6T 2A9
ABSTRACT
Distribution data for 15 species of Capniidae are presented, supplementing the anno-
tated checklist of Ricker and Scudder (1975). Five species (Bolshecapnia milami,
Capnia coloradensis, C. petila, C. sextuberculata and Utacapnia trava) are reported
from British Columbia for the first time.
INTRODUCTION
Since the publication of Ricker and Scudder’s (1975) annotated checklist of the Plecoptera
of British Columbia, knowledge of the local distribution of the slender winter stoneflies
(Capniidae) has increased considerably. Ricker (1943) documented the occurrence of many
valley inhabiting species in southwestern British Columbia, but made few visits to higher
altitudes during the winter and early spring. In recent years many collections have been made
in these habitats, especially in the southern part of the province. However, the central and
northern sections of the province remain largely terra incognita, although recent collecting in
the Yukon allows some interpolation of range information. The following data are largely the
result of collections made by myself and colleagues; these specimens are in the Spencer
Entomological Museum, University of British Columbia. However, collections in Rocky
Mountain parks made by D.B. Donald and R.S. Anderson of the Canadian Wildlife Service are
also included; the lentic stoneflies of these collections were reported in a summary fashion in
Donald and Anderson (1980). These specimens are in the collections of the Canadian Wildlife
Service, Edmonton, Alberta.
78 J. EntomMov Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
NOMENCLATURE
The nomenclature follows Zwick (1973) and differs from that of Ricker and Scudder (1975)
in the recognition of Mesocapnia and Utacapnia as separate genera, rather than as subgenera
of Capnia. Ricker and Scudder also treated C. gracilaria as C. promota Frison.
SPECIES LIST
This list includes only those records that extend or fill in gaps in ranges as indicated by the
list of Ricker and Scudder (1975). Many records in the following list are from E.C. Manning
Provincial Park, which is therefore abbreviated (MPP) following the initial record. Each
record is followed by the collector’s name or initials in parentheses. The key to initials is as
follows: H& AB — Hugh and Aileen Brock; RJC —R.J. Cannings; SGC — S.G. Cannings; DBD
— D.B. Donald; CSG — C.S. Guppy; LM — L. Moore [Vasington]; RM — R. Moore.
Bolshecapnia milami (Nebeker and Gaufin)
Manning Provincial Park, Similkameen R., near park headquarters, 1190 m, 11.11.1976
(SGC), 19.iii.1982 (SGC); MPP, Similkameen R. at Chuwanten Cr., 1190 m, 1.1ii.1981 (SGC).
These are the first records for British Columbia; this species was previously known from the
Rocky Mountains of Alberta and northern United States (Donald and Anderson 1977,
Baumann et al. 1977).
B. sasquatchi (Ricker)
MPP, Similkameen R., Cambie Cr. ski area, 1350 m, 19.i11.1983 (SGC); MPP, Skagit R., 838
m, 18.11.1983 (SGC).
Capnia cheama Ricker
Bulkley R., Smithers, 19.iv.1989 (D. Weir); Sedan Cr., 10 km W of Kitwanga, 6.iv.1989 (D.
Weir); Skeena R., 5 km W of Kitwanga, 2.iv.1989 (D. Weir).
These records fill in a huge gap between the type locality near Chilliwack, B.C. and a record
from Rampart House in the northern Yukon (specimens in Canadian National Collection,
Ottawa). This rare species of large streams and rivers is also known from the Rocky Mountains
of Alberta and Montana (Baumann et al. 1977).
Capnia coloradensis Claassen
Kelsall L. area, Haines Road, 28.iv.1981 (S. Hannon), 2.v.1982 (M. Taitt); MPP, Similka-
meen R., at Chuwanten Cr., 1.111.1981 (SGC); MPP, Similkameen R., near park headquarters,
1190 m, 11.11.1976 (SGC), 16.i11.1980 (RJC), 14.11.1982 (SGC), 19.111.1982 (SGC); Shingle
Cr., 21.i11.1982 (SGC); Similkameen R., Princeton, 19.111.1982 (SGC); Similkameen R., 2 km
below Similkameen Falls, 20.11.1982 (SGC), 19.i11.1982 (SGC); Skeena R., 5 km W of
Kitwanga, 22.111.1989 (D. Weir).
These are the first records for British Columbia, and extend the known distribution into the
Coast and Cascade Mountains for the entire length of the province. Baumann et al. (1977) give
the range as the Rocky Mountains of the United States, and Flannagan and Cobb (1983)
extended it as far east as Manitoba on the Canadian Great Plains.
C. elongata Claassen
Mamquam R., 1.6 km upstream of Squamish R., 4.11.1979 (SGC).
C. gracilaria Claassen
Ellis Cr., Penticton, 10.iii.1985 (J.A. Garland); Garibaldi Provincial Park, Garibaldi L.,
1.vii.1976 (K. Cehak), 13.vi.1981 (SGC); Keremeos Cr., 15.vii.1976 (SGC); MPP, Similka-
meen R. near park headquarters, 16.ii1.1980 (RJC), 14.11.1982 (SGC, R&LM), 19.iii.1982
(SGC), 19.ii1.1983 (SGC), 6.iii.1983 (SGC); ibid., 1250 m (first bridge south of pass),
6.111.1983; ibid., Cambie Cr. ski area, 1350 m, 19.iii.1983 (SGC); ibid., 24.iii.1984 (H&AB);
ibid., 2.iv.1989 (SGC, H&AB); MPP, Sumallo R., 14.iii.1982 (SGC), 19.iii.1982 (SGC);
Penticton Cr., 21.111.1982 (SGC); Shatford Cr., 21.iii.1982 (SGC); Shingle Cr., 21.iii.1982
(SGC); Similkameen R., Princeton, 19.iii.1982 (SGC); Similkameen R., 2 km below Similka-
meen Falls, 19.111.1982 (SGC), Skeena R., 5 km W of Kitwanga, 22.iii.1989 (D.Weir),
2.iv.1989 (D. Weir).
After C. nana, this is probably the commonest montane Capnia in British Columbia.
Although these records are all from the southern end of the province, C. gracilaria is also
common in the southern Yukon (unpublished data), so it is undoubtedly widely distributed in
British Columbia. Baumann et al. (1977) give its range as the Coast, Cascade and Rocky
Mountains and the Northern Great Plains; in Canada it reaches as far east as Manitoba
(Flannagan and Cobb 1983).
J. Entomot Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989 719
C. melia Frison
Botanie L., Lytton, beside creek, 1067 m, 31.iii.1983 (CSG); Cypress Provincial Park,
13.iii.1982 (SGC); Garibaldi Provincial Park, Diamond Head Trail, 1067-1372 m, 5.iv.1981
(SGC), 17.iv.1981 (SGC); Keremeos Cr., 15.ii.1976 (SGC); MPP, Fat Dog Cr., 28.iv.1985,
H& AB; MPP, Similkameen R., near park headquarters, 14.11.1982 (SGC, R&LM); 19.i11.1982
(SGC), 6.iii.1983 (SGC), 19.iii.1983 (SGC); MPP, Similkameen R., “Cambie Cr.” ski area,
2.iv.1989 (SGC); MPP, Sumallo R., 14.11.1982 (SGC).
C. nana Claassen
Botanie L., Lytton, beside creek, 1067 m, 31.iii.1983 (CSG); Cypress Provincial Park, 1000
m, 4.iv.1980 (RJC); Ellis Cr., Penticton, 10.iii.1985 (J.A. Garland); Glacier National Park,
Loop Brook, 1170 m, 18.iv.1980 (J.G. Woods); Keremeos Cr., 15.11.1975 (SGC); MPP, Castle
Cr., 11.ii.1979 (SGC), 14.ii.1982 (SGC); MPP, Chuwanten Cr., 1.ii1.1981 (SGC, R&LM),
14.11.1982 (SGC); MPP, Fat Dog Cr., 6.iii.1983 (SGC), 19.i11.1983 (SGC), 28.iv.1985
(H&AB); MPP, Fat Dog Cr., upper headwaters, 1524-1830 m, 28.11.1981 (SGC); Flash L. and
“Flash Cr.’’, 18.11.1983 (SGC); MPP, Monument 83 Trail, 1220-1372 m, 1.i11.1981 (SGC,
LM); MPP, Similkameen R., 17.ii.1983 (SGC); ibid., ““Cambie Cr.” ski area, 1350 m,
16.11.1980 (SGC), 16.iii1.1980 (SGC), 14.iii.1981 (C. Edman), 15.iii.1981 (C. Edman),
19.ii1.1983 (SGC), 24.iii1.1984 (H&AB), 2.iv.1989 (SGC, H&AB); ibid., 1400-1450 m,
19.iii1.1983 (SGC); MPP, Similkameen R., at Chuwanten Cr., 17.11.1980 (SGC), 1.iii1.1981
(SGC); ibid., near park headquarters, 1190 m, 16.11.1976 (SGC), 11.11.1979 (SGC), 16.111.1980
(RJC), 14.11.1982 (SGC, R&LM), 19.iii.1982 (SGC), 6.iii.1983 (SGC), 19.111.1983 (SGC);
ibid. near confluence of Pasayten R., 20.ii.1982 (SGC); ibid., 1250 m, first bridge south of
Allison Pass, 6.iii.1983 (SGC); Paulson Summit, near Castlegar, 26.11.1982 (P. Wood); Shingle
Cr., Penticton, 21.iii.1982 (SGC); Skeena R., 5 km W of Kitwanga, 2.iv.1989 (D. Weir); Wells
Gray Provincial Park, Blackwater Cr., 701 m, 24.ii.1985 (T. Goward); Wells Gray Provincial
Park, McLeod Hill, 853 m, 16.11.1985 (T. Goward).
This is by far the most abundant capniid of small mountain streams in British Columbia; the
fact that Ricker and Scudder (1975) report only three previous records is an indication that few
entomologists have collected in the mountains in the early spring.
C. petila Jewett
Botanie L., Lytton, beside creek, 1067 m, 31.ii1.1983 (CSG); MPP, Similkameen R.,
““Cambie Cr.”’ ski area, 24.i11.1984 (H&AB), 2.1v.1989 (SGC, H& AB), Skeena R., 5 km W of
Kitwanga, 22.111.1989 (D. Weir); 2.iv.1989 (D. Weir).
These are the first records for British Columbia. This is a relatively rare species, but is
widely distributed in the Western Cordillera. Baumann et al. (1977) give the range as the
Cascade and Rocky Mountains (north to Banff) and recent unpublished records from the
southwestern Yukon extend the range throughout British Columbia. It appears to emerge later
than C. nana and other, more common, congeners.
C. sextuberculata Jewett
Botanie L., Lytton, beside creek, 1067 m, 31.11.1983 (CSG).
This is the first record for British Columbia; previously recorded from the Cascade
Mountains of Oregon and the Rocky Mountains of Alberta and Montana (Baumann et al.
1977).
Isocapnia spenceri Ricker
Atnarko R., spawning channel near Stuie, 11.iv.1989 (M. Wigle).
Mesocapnia autumna (Baumann and Gaufin)
Similkameen R., Keremeos, 9.x.1982 (SGC); Similkameen R., Princeton, 11.x.1982 (SGC).
Mesocapnia oenone (Neave)
Elk Lake Provincial Park, lower Elk Lake, 1735 m, 28.vii1.1977 (DBD); MPP, Similkameen
R., near park headquarters, 1190 m, 12.x.1981 (SGC); Hamber Provincial Park, Fortress L.,
1337 m, 26.ix.1979 (DBD).
Utacapnia columbiana (Claassen)
Atlin L., Warm Bay, found dead in Picea sap, 22.vi.1982 (SGC); Bulkley R., Smithers,
19.iv.1989 (D. Weir); Sedan Cr., 10 km W of Kitwanga, 6.iv.1989 (D. Weir); Skeena R., 5 km
W of Kitwanga, 22.i11.1989 (D. Weir); 2.iv.1989 (D. Weir); Tetsa R., campground on Alaska
Highway, 16.vi.1982 (SGC).
80 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
U. trava (Nebeker and Gaufin)
Akolkolex Cr., at Columbia R., 460 m, 24.11.1980 (J.G. Woods); Beatty L., 31.vii.1977
(DBD); MPP, Lightning Lakes, beside open section of lake, 1220 m, 18.ii.1983 (SGC); MPP,
Similkameen R., at Chuwanten Cr., 1.1i1.1981 (SGC); ibid., near park headquarters, 1190 m,
11.11.1979 (SGC), 14.11.1982 (SGC, R&LM), 6.111.1983 (SGC); ibid., near Pasayten R.,
20.11.1982 (SGC); Mount Robson Provincial Park, Kinney L., 985 m, 9.vi.1979 (DBD); Mount
Robson Provincial Park, Yellowhead Lake, 1104 m, 23.v.1976 (DBD); Similkameen R., at
Bromley Provincial Park, 19.i11.1982 (SGC); ibid., Keremeos, 19.1ii.1982 (SGC); ibid.,
Princeton, 19.iii.1982 (SGC); ibid., 2 km below Similkameen Falls, 20.11.1982, 19.iii.1982
(SGC).
These are the first detailed records for the province, although Donald and Anderson (1980)
and Donald and Patriquin (1983) used British Columbia records in analyses of lentic
stoneflies. These records extend the known distribution into the Cascade Mountains. Baumann
et al. (1977) give the range as the Canadian and Northern Rocky Mountains (north to Banff);
Dosdall and Lemkuhl (1979) and Flannagan and Cobb (1983) extended it onto the Canadian
Great Plains.
ACKNOWLEDGEMENTS
I would like to thank all the people who collected specimens for me; their names-are
included with the records. D.B. Donald generously gave me his original data sheets for his
Continental Divide collection sites. The assistance of the British Columbia Ministry of Parks
in granting permission to collect in various parks is also gratefully acknowleged.
REFERENCES
Baumann, R.W., A.R. Gaufin and R.F. Surdick. 1977. The stoneflies (Plecoptera) of the Rocky Mountains. Mem.
Am. ent. Soc. (Philadelphia) 31. 208 pp.
Donald, D.B. and R.S. Anderson. 1980. The lentic stoneflies (Plecoptera) from the Continental Divide region of
southwestern Canada. Can. Ent. 112:753-758.
Donald, D.B. and D.E. Patriquin. 1983. The wing length of lentic Capniidae (Plecoptera) and its relationship to
elevation and Wisconsin glaciation. Can. Ent. 115:921-926.
Dosdall, L. and D.M. Lemkuhl. 1979. Stoneflies (Plecoptera) of Saskatchewan. Quaest. Ent. 15:3-116.
Flannagan, J.F. and D.G. Cobb. 1983. New records of winter stoneflies (Plecoptera) from Manitoba with notes on
their zoogeographical origins. Can. Ent. 115:673-677.
Ricker, W.E. 1943. Stoneflies of southwestern British Columbia. Indiana University Publications, Science Series
12:1-145.
Ricker, W.E. and G.G.E. Scudder. 1975. An annotated checklist of the Plecoptera (Insecta) of British Columbia.
Syesis 8:333-348.
Zwick, P. 1973. Insecta: Plecoptera, Phylogenetisches System und Katalog. Das Tierreich 94:1-465.
CHALCIDOIDS (HYMENOPTERA) REARED FROM ARTEMISIA TRIDENTATA
(ASTERACEAE) GALLS IN BRITISH COLUMBIA, CANADA
JORGE A. SANTIAGO-BLAY
DEPARTMENT OF ENTOMOLOGICAL SCIENCES
UNIVERSITY OF CALIFORNIA
BERKELEY, CA 94720 U.S.A.
While on a collecting trip in British Columbia (Canada), I took 39 stem galls from
sagebrush, Artemisia tridentata (Nuttall) (Asteraceae). Four chalcidoid spp. (Hymenoptera)
emerged from the galls, representing four families. This paper reports the times of emergence
after collection, diameter and location of exit holes and wasp’s lifespans.
The galls were collected along a roadside, 15 kms NW of Lower Nicola, B.C., on 22 June
1988 and placed in 35 ml plastic cups. The ovate galls were located mostly on the basal two-
thirds of the shoots. Sixteen of the reared galls (41%) produced chalcidoids. The galls, which
were kept at room temperature were observed daily and were not moistened, to prevent the
J. EnromMot Soc. Brit. COLUMBIA 86 (1989), SEpr. 30, 1989 81
spread of fungi. No food was provided to the wasps. The maximum lengths and widths to it (=
width) were measured for the 14 galls from which insects emerged. They averaged 12.1 mm
long (sd = 2.8, range = 9-18) and 7.7 mm wide (sd = 2.4, range = 7-12). All galls were dissected
211 days after collection; which was 180 days after the last emergence. The dissected galls
were examined for remains of insect associates within the gall. Puparia, or their remains,
possibly of tephridids were found inside most galls. For each taxon, only the ranges for
parameters are given because of the small sample size. The specimens, labelled VOUCHER
SPECIMEN, are deposited in the Systematic Entomology Laboratory (Beltsville, MD, USA).
Torymus citripes (Huber) (Torymidae)
Sample size: two males, five females. Time of emergence: males, 11 and 14 days; females, 3
to 14. In five cases the emergence hole was located at the apical third (one male emerged at the
very apex); two cases with no gall association. Exit hole diameter varied from 0.72 to over 1.85
mm; most within 1 - 2 mm. Lifespan, males three to four days; females three to six. This wasp
is widespread in western North America, reported in association with Helianthus lenticularis
(Compositae) and parasitizes the tephritid flies, Euaresta bullans (Wied.), Eutreta diana (O.
S.), and Gymnocarena tricolor (Doane) (Krombein et al. 1979).
Two dwarf males emerged and they appear to be conspecific (Grisell, pers. comm.); their
data as follows: time of emergence, 11 and 14 days; emergence hole at apex, diameter range,
1.05 - 1.14 mm; lifespan, two to three days.
Eurytoma sp. (Eurytomidae)
Sample size: one male, four females. Time of emergence: male, 15 days; females 9 to 14. In
all cases, the emergence hole was located at the apical third (one female emerged at the very
apex). Exit hole diameter range: females 0.66 to over 1.54 mm; male, 0.43 mm. Lifespan, male
two days; females four to seven. .LP Eupelmus sp. (Eupelmidae)
Sample size: one female. Time of emergence, 27 days; emerged at apical third apex. Exit hole,
0.54 mm. Lifespan, five days.
Sympiesis sp. (?) (Eulophidae)
Sample size: one male (?). The gall has a large, (=> 4.13 mm) orifice (apparently emergence
hole of the gall former) located at the apical third. Lifespan, 15 days.
Several species of torymids, eupelmids, pteromalids, platygasterids and encyrtids
(Hymenoptera) have been reared from galls of A. tridentata (Jones et al. 1983). Although often
torymids are ectoparasites of gall forming insects in the Cecidomyiidae and the Tephritidae
(Diptera) (Yoshimoto 1984), their biologies can not be inferred without more extensive and
detailed observations (Grisell 1988). One species, Torymus aeneoscapus Huber, has been
determined to be a parasitoid of gall-forming midges in Idaho (Jones et al. 1983). All of the
insects herein reported are new insect association records for A. tridentata for British
Columbia.
ACKNOWLEDGMENTS
Drs. E. E. Grisell and M. E. Schauff (Taxonomic Services Unit, Systematic Entomology
laboratory, Beltsville, MD) and Kim Hoelmer (Department of Entomological Sciences,
University of California, Berkeley) identified the wasps. Dr. Kenneth Hagen (UCB) identified
the gall contents. Julie Wolf (Scientific Photography Laboratory, UCB) did the photographic
work. Hagen, Patrick Ruggle (UCB) and two anonymous reviewers read the manuscript and
Suggested modifications. My gratitude to all of them.
REFERENCES
Grisell, E. E. 1988. The relationship of biological facts to phylogenetic fantasy in the Torymidae (Hymenoptera).
Proc. XVIII Inter. Congr. Entomol. (Vancouver, Canada). p. 10.
Jones, R. G., R. J. Gagné and W. F. Barr. 1983. Biology and taxonomy of the Rhopalomyia gall midges (Diptera:
Cecidomyiidae) of Artemisia tridentata Nuttall (Compositae) in Idaho. Contr. Amer. Entomol. Inst. 21:1-79.
Krombein, K. V., P. D. Hurd, Jr., D. R. Smith and B. D. Burks. 1979. Catalog of Hymenoptera in America North of
Mexico. Vol. 1 Symphyta and Apocrita. Smithsonian Institution Press. Washington, D.C. 1198 pp.
Yoshimoto, C. M. 1984. The families and subfamilies of Canadian chalcidoid wasps Hymenoptera: Chalcidoidea.
In, The insects and arachnids of Canada. Part 12. 149 pp.
82 J. ENTOMOL Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
THE APHIDS (HOMOPTERA:APHIDIDAE) OF BRITISH COLUMBIA
19. FURTHER ADDITIONS
A.R. ForBEs! AND C.K. CHAN!
1RESEARCH STATION, AGRICULTURE CANADA
VANCOUVER, BRITISH COLUMBIA, V6T 1X2
ABSTRACT
Four species of aphids and new host records are added to the taxonomic list of the aphids
of British Columbia.
INTRODUCTION
Three hundred ninety-seven species of aphids collected from 1052 hosts or in traps, and
2043 aphid-host plant associations were recorded in fourteen previous lists of the aphids of
British Columbia (Forbes, Frazer and MacCarthy 1973; Forbes, Frazer and Chan 1974; Forbes
and Chan 1976, 1978, 1980, 1981, 1983, 1984, 1985, 1986a, 1986b, 1987, 1988; Forbes, Chan
and Foottit 1982). The present list adds 4 aphid species (indicated with an asterisk in the list)
and 183 aphid-host plant associations to the previous lists. Seventy-one of the new aphid-host
plant associations are plant species not recorded before. As Aphis herachella Davis is
synonymized with A. helianthi Monell (Addicott 1981), the additions bring the number of
known aphid species in British Columbia to 400. Aphids have now been collected from 1124
different host plants and the total number of aphid-host plant associations is 2233.
Two of the four newly recorded aphid species are of economic importance. The Russian
wheat aphid, Diuraphis noxia (Mordvilko ex Kurdjumov), was first detected in Creston in
November 1988, as a result of a survey conducted in the winter wheat fields and grass seed
fields. It poses a serious threat to production of cereals and grass seeds in British Columbia.
The tobacco aphid, Myzus nicotianae Blackman (red form), feeding on tobacco in Victoria is
the first confirmed record of this aphid in Canada. It has the same host range as Myzus persicae
(Sulzer), and was shown to be a vector of beet western yellows and potato leaf roll viruses
(unpublished data).
The aphid names are listed alphabetically by species and are in conformity with Eastop and
Hille Ris Lambers (1976), except Glabromyzus schlingeri Hille Ris Lambers has been
changed to Utamphorophora schlingeri (Hille Ris Lambers) based on Cook’s finding (1984).
The location of a new collection site is given in Table I. The reference point is the same as that
shown on the map which accompanies the basic list (Forbes, Frazer and MacCarthy 1973).
TABLE 1.
Collection site of aphids, with airline distance from reference point.
Distance
Locality Reference Point Dir km mi
Garvin Creek Prince George NW 13 8
LIST OF SPECIES
ALNIFOLIAE (Williams 1911), PROCIPHILUS
Pinus monticola: Oliver, Sep24/88.
*ANTIRRHINII (Macchiati 1883), MYZUS
Datura stramonium: Vancouver (CDA), Oct18/88.
J. ENromMot Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 83
ASCALONICUS Doncaster 1946, MYZUS
Alchemilla vulgaris: Vancouver (CDA), Feb20/89.
Anthriscus cerefolium: Vancouver (CDA), Feb20/89.
Fragaria vesca ‘Semperflorens’: Vancouver (CDA), Feb20/89.
Horminum pyrenaicum: Vancouver (UBC), Apr15/88.
Potentilla alba: Vancouver (UBC), Apr15/88.
Stellaria media: Vancouver (UBC), Sep16/88.
Verbena ‘Ideal Florist’: Vancouver (CDA), Mar3/89.
ASPARAGI (Mordvilko 1929), BRACHYCORYNELLA
Asparagus officinalis: Vancouver (CDA), Dec29/88.
AVELLANAE (Schrank 1801), CORYLOBIUM
Corylus maxima ‘Purpurea’: Vancouver (UBC), Apr26/88, May30/88.
BERBERIDIS (Kaltenbach 1843), LIOSOMAPHIS
Berberis actinacantha: Vancouver (UBC), Jul20/88.
BETULAE (Koch 1855), EUCERAPHIS
Betula pendula: Vancouver (UBC), Sep8/87, Sep29/87.
BRASSICAE (Linnaeus 1758), BREVICORYNE
Brassica oleracea var. gemmifera ‘Jade Cross’: Vancouver (UBC), Sep30/88.
BREVISPINOSA (Gillette & Palmer 1924), CINARA
Pinus contorta: Lac La Hache, Jun27/80.
CALLIPTERUS (Hartig 1841), CALLIPTERINELLA
Betula pendula: Vancouver (UBC), Sep8/87.
CAPILANOENSE Robinson 1969, AULACORTHUM
Rubus spectabilis: Peace Arch Park, Aug1/88; Vancouver, Jun21/88.
CARNOSUM (Buckton 1876), MICROLOPHIUM
Urtica dioica: Peace Arch Park, Aug1/88.
CERASI (Fabricius 1775), MYZUS
Prunus domestica: Pemberton, Apr12/88.
CERTUS (Walker 1849), MYZUS
Gomphrena globosa: Vancouver (CDA), Oct18/88.
Nicotiana clevelandii: Vancouver (CDA), Mar1/89.
CIRCUMFLEXUM (Buckton 1876), AULACORTHUM
Akebia quinata: Vancouver (UBC), Jun14/88.
Aquilegia x hybrida ‘Dragonfly Mix’: Vancouver (UBC), Nov22/88.
Gomphrena globosa: Vancouver (CDA), Feb20/89.
Schizophragma hydrangeoides: Vancouver (UBC), Jun30/88, Aug5/88.
Vitis vinifera ‘Concord’: Vancouver, May29/88.
CITRICOLA van der Goot 1912, APHIS
Stranvaesia davidiana: Vancouver (UBC), Jun14/88.
COLORADENSIS (Gillette 1917), CINARA
Picea glauca: Garvin Creek, Sep4/87.
COWEN I (Cockerell 1905), TAMALIA
Arctostaphylos uva-ursi ssp. stipitata: Vancouver (UBC), Sep30/88.
Arctostaphylos uva-ursi ‘Vancouver Jade’: Vancouver, Sep15/88.
DORSATUM Richards 1967, AULACORTHUM
Gaultheria shallon: Vancouver (UBC), Apr15/87, May4/88, Jun14/88, Jun30/88.
ENIGMAE Hottes & Frison 1931, RHOPALOSIPHUM
Typha orientalis: Vancouver (UBC), Sep29/87, Nov24/87.
EUPHORBIAE (Thomas 1878), MACROSIPHUM
Arachis hypogaea ‘Early Spanish’: Vancouver (CDA), Feb20/89.
Chenopodium amaranticolor: Vancouver (CDA), Mari/89.
Eucalyptus cinerea: Vancouver (UBC), Aug24/88.
84 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
Ruta graveolens: Vancouver (UBC), Jun8/88.
Ulmus americana: Burnaby, Jul21/84.
FABAE Scopoli 1763, APHIS
Dracunculus vulgaris: Vancouver, Jun18/88.
Rheum rhabarbarum: Vancouver, Jun19/88.
FOENICULI (Passerini 1860), HYADAPHIS
Lonicera ‘Dropmore Scarlet’: Vancouver (UBC), Sep30/88.
FRAGAEFOLII (Cockerell 1901), CHAETOSIPHON
Potentilla anserina: Goldstream, Aug20/59; Sea Island, Aug21/59.
FRAGARIAE (Walker 1848), SITOBION
Typha orientalis: Vancouver (UBC), Nov24/87.
GENTNERI (Mason 1947), FIMBRIAPHIS
Crataegus monogyna: Vancouver, Apr26/88.
GILLETTEI Davidson 1915, EUCERAPHIS
Alnus rubra: Vancouver (UBC), Sep28/87, Oct8/87, Oct9/87.
HELICHRYSI (Kaltenbach 1843), BRACHYCAUDUS
Myosotidium hortensia: Vancouver (UBC), Feb24/88.
Prunus cerasifera ‘Atropurpurea’: Vancouver, Jun23/88.
HOLODISCI Robinson 1984, APHIS
Holodiscus discolor: Vancouver (UBC), Jun9/88.
HUMBOLDTI (Essig 1941), UTAMPHOROPHORA
Physocarpus malvaceus: Vancouver (UBC), Nov4/88.
HUMULI (Schrank 1801), PHORODON
Prunus cerasifera ‘Atropurpurea’: Kamloops, Jun26/88; Vancouver, Jun23/88.
IDAEI van der Goot 1912, APHIS
Rubus idaeus: Vancouver, Aug25/60.
LACTUCAE (Passerini 1860), ACYRTHOSIPHON
Lactuca serriola: Kamloops, Jun26/88.
LONGICAUDA (Richards 1963), EOESSIGIA
Spiraea douglasii ssp. menziesii: Vancouver (UBC), Jun8/88, Jul9/88.
LONICERAE (Siebold 1839), RHOPALOMYZUS
Lonicera ‘Dropmore Scarlet’: Vancouver (UBC), Sep30/88.
MACROSIPHUM (Wilson 1912), ACYRTHOSIPHON
_ Amelanchier laevis: Vancouver (UBC), Jul22/88.
MENZIESIAE (Robinson 1969), ILLINOIA
Menziesia ferruginea ssp. ferruginea: Mount Seymour, Sep3/88.
MODESTUM (Hottes 1926), MYZODIUM
Polytrichum juniperinum: Vancouver (UBC), Sep8/87.
NERVATA (Gillette 1908), WAHLGRENIELLA
Arbutus menziesii: Vancouver (UBC), Dec16/88.
*NICOTIANAE Blackman 1987, MYZUS
Alchemilla vulgaris: Vancouver (CDA), Sep3/88.
Anthriscus cerefolium: Vancouver (CDA), Nov9/88.
Apium graveolens: Vancouver (CDA), Nov9/88.
Arachis hypogaea ‘Early Spanish’: Vancouver (CDA), Nov9/88.
Asparagus officinalis: Vancouver (CDA), Nov9/88.
Beta vulgaris: Vancouver (CDA), Dec9/88.
Brassica juncea ‘Florida Broadleaf’: Vancouver (CDA), Sep3/88.
Brassica juncea ‘Tendergreen Mustard Spinach’: Vancouver (CDA), Sep3/88.
Brassica pekinensis: Vancouver (CDA), Sep3/88.
Capsella bursa-pastoris: Vancouver (CDA), Sep12/88.
Catharanthus roseus: Vancouver (CDA), Sep3/88.
Chenopodium capitatum: Vancouver (CDA), Nov9/88.
Chenopodium murale: Vancouver (CDA), Nov9/88.
Chenopodium quinoa: Vancouver (CDA), Nov9/88.
J. Enromot Soc. Brir. COLUMBIA 86 (1989), SEPT. 30, 1989
Claytonia sibirica var. sibirica: Vancouver (CDA), Feb20/89.
Cucumis sativus ‘Straight Eight’: Vancouver (CDA), Feb28/89.
Datura stramonium: Vancouver (CDA), Sep3/88.
Daucus carota: Vancouver (CDA), Nov9/88.
Dianthus barbatus: Vancouver (CDA), Jan5/89.
Fragaria vesca ‘Semperflorens’: Vancouver (CDA), Nov9/88.
Lactuca sativa: Vancouver (CDA), Jan5/89.
Lycopersicon lycopersicum ‘Rutgers’: Vancouver (CDA), Jan15/89.
Mimosa pudica: Vancouver (CDA), Feb20/89.
Nicotiana benthamiana: Vancouver (CDA), Sep26/88.
Nicotiana clevelandii: Vancouver (CDA), Sep26/88.
Nicotiana debneyi: Vancouver (CDA), Sep26/88.
Nicotiana glutinosa: Vancouver (CDA), Sep26/88.
Nicotiana rustica: Vancouver (CDA), Sep26/88.
Nicotiana sp.: Victoria, Jun15/88.
Nicotiana sylvestris: Vancouver (CDA), Sep26/88.
Nicotiana tabacum ‘Harrownova’: Vancouver (CDA), Oct10/88.
Nicotiana tabacum ‘Havana 425’: Vancouver (CDA), Oct10/88.
Nicotiana tabacum ‘Samsun’: Vancouver (CDA), Oct10/88.
Nicotiana tabacum ‘White Burley’: Vancouver (CDA), Oct10/88.
Nicotiana tabacum ‘Xanthi’: Vancouver (CDA), Oct10/88.
Petunia ‘Coral Magic’: Vancouver (CDA), Sep3/88.
Physalis pubescens: Vancouver (CDA), Sep3/88.
Plantago lanceolata: Vancouver (CDA), Jan5/89.
Plantago major: Vancouver (CDA), Jan26/89.
Raphanus sativus: Vancouver (CDA), Dec9/88.
Solanum tuberosum: Vancouver (CDA), Sep3/88.
Verbena ‘Ideal Florist’: Vancouver (CDA), Feb28/89.
Verbesina encelioides: Vancouver (CDA), Jan5/89.
Vicia faba: Vancouver (CDA), Mar1/89.
Zinnia elegans: Vancouver (CDA), Sep3/88.
*NIGRA (Wilson 1919), CINARA
Pinus contorta: Quesnel, Aug11/80.
*NOXIA (Mordvilko ex Kurdjumov 1913), DIURAPHIS
Phleum pratense: Creston, Nov23/88.
Triticum x aestivum: Creston, Nov23/88.
NYMPHAEAE (Linnaeus 1761), RHOPALOSIPHUM
Anthriscus cerefolium: Vancouver (CDA), Feb20/89.
Lemna minor: Vancouver (UBC), Sep23/88.
ORNATUS Laing 1932, MYZUS
Abelia x grandiflora: Vancouver (CDA), Dec9/88.
Anthriscus cerefolium: Vancouver (CDA), Mar8/89.
Capsella bursa-pastoris: Vancouver (UBC), Feb23/88.
Catharanthus roseus: Vancouver (CDA), Feb20/89.
Euonymus japonica ‘Albo-marginata’: Vancouver (UBC), Jan5/89.
Fatsia japonica: Vancouver (UBC), Jan26/89.
Garrya elliptica: Vancouver (UBC), Dec16/88.
Lactuca sativa: Vancouver (CDA), Jan13/89, Feb20/89.
Lavandula angustifolia ssp. angustifolia: Vancouver (UBC), Jan26/89.
Oxalis adenophylla: Vancouver (UBC), Jul20/88.
Plantago lanceolata: Vancouver (CDA), Jan26/89.
Potentilla fruticosa: Vancouver (UBC), Jun9/88.
Rumex obtusifolius ssp. obtusifolius: Vancouver (UBC), Feb23/88.
PARVIFOLII Richards 1967, MACROSIPHUM
Vaccinium alaskaense: Mount Seymour, Sep3/88.
86 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
PERGANDEI (Wilson 1919), CINARA
Pinus contorta: Williams Lake, Jun18/80.
PERSICAE (Sulzer 1776), MYZUS
Alchemilla vulgaris: Vancouver (CDA), Oct18/88.
Arachis hypogaea ‘Early Spanish’: Vancouver (CDA), Oct18/88.
Brassica juncea ‘Florida Broadleaf’: Vancouver (CDA), Oct18/88.
Brassica juncea ‘Tendergreen Mustard Spinach’: Vancouver (CDA), Oct18/88.
Brassica oleracea var. gemmifera ‘Jade Cross’: Vancouver (UBC), Sep30/88.
Brassica pekinensis: Vancouver (CDA), Oct18/88.
Catharanthus roseus: Vancouver (CDA), Feb20/89.
Chenopodium amaranticolor: Vancouver (CDA), Feb20/89.
Chenopodium capitatum: Vancouver (CDA), Feb20/89.
Chenopodium murale: Vancouver (CDA), Feb20/89.
Chenopodium quinoa: Vancouver (CDA), Feb20/89.
Cucumis sativus ‘Straight Eight’: Vancouver (CDA), Nov21/88.
Dianthus barbatus: Vancouver (CDA), Nov21/88.
Fragaria vesca ‘Semperflorens’: Vancouver (CDA), Nov21/88.
Lycopersicon lycopersicum ‘Rutgers’: Vancouver (CDA), Nov21/88.
Nicotiana benthamiana: Vancouver (CDA), Nov21/88.
Nicotiana clevelandii: Vancouver (CDA), Nov21/88.
Nicotiana debneyi: Vancouver (UBC), Nov21/88.
Nicotiana rustica: Vancouver (CDA), Nov21/88.
Nicotiana sylvestris: Vancouver (CDA), Nov21/88.
Nicotiana tabacum ‘Xanthi’: Vancouver (CDA), Nov21/88.
Petunia ‘Coral Magic’: Vancouver (CDA), Feb20/89.
Plantago lanceolata: Vancouver (CDA), Jan15/89.
Raphanus sativus: Vancouver (CDA), Sep9/88.
Solanum tuberosum: Surrey, Aug15/88.
Verbena ‘Ideal Florist’: Vancouver (CDA), Jan15/89.
Verbesina encelioides: Vancouver (CDA), Jan15/89.
PISUM (Harris 1776), ACYRTHOSIPHON
Arachis hypogaea ‘Early Spanish’: Vancouver (CDA), Feb20/89.
POMI de Geer 1773, APHIS
Photinia x fraseri: Richmond, Jul14/88.
PRUNI (Geoffroy 1762), HYALOPTERUS
Typha orientalis: Vancouver (UBC), Aug25/87.
PSEUDOTAXIFOLIAE Palmer 1952, CINARA
Pseudotsuga menziesii: Garvin Creek, Sep4/87.
PTERINIGRUM Richards 1972, AULACORTHUM
Akebia quinata: Vancouver (UBC), Jun14/88, Nov17/88.
Alchemilla vulgaris: Vancouver (UBC), Nov17/88.
QUADRITUBERCULATA (Kaltenbach 1843), BETULAPHIS
Betula pendula: Vancouver (UBC), Sep8/37.
RHAMNI (Clarke 1903), SITOBION
Rhamnus purshiana: Vancouver (UBC), Nov5/88.
RIBISNIGRI (Mosley 1841), NASONOVIA
Lapsana communis: Vancouver, Jun6/88.
ROSAE (Linnaeus 1758), MACROSIPHUM
Rosa ‘Peace’: Vancouver (UBC), Jan26/89.
Rosa ‘Playboy’: Vancouver (UBC), Mar21/88.
Rosa rugosa ‘Rubra’: Vancouver (UBC), Nov17/88.
Rosa ‘Vienna Woods’: Vancouver (UBC), Mar21/88.
ROSARUM (Kaltenbach 1843), MYZAPHIS
Potentilla fruticosa: Vancouver, Jun25/88.
Rosa rubrifolia: Vancouver (UBC), Jun9/88.
J. ENTOMOL Soc. BRIT. COLUMBIA 86 (1989), SEPT. 30, 1989
SAMBUCI Linnaeus 1758, APHIS
Sambucus nigra: Vancouver (UBC), Jun8/88.
SCHLINGERI (Hille Ris Lambers 1966), UTAMPHOROPHORA
Juncus effusus var. pacificus: Vancouver (CDA), Jan13/89.
SOLANI (Kaltenbach 1843), AULACORTHUM
Anthriscus cerefolium: Vancouver (CDA), Feb20/89.
Arachis hypogaea ‘Early Spanish’: Vancouver (CDA), Nov9/88.
Camassia cusickii: Vancouver (UBC), Apr15/88.
Chenopodium capitatum: Vancouver (CDA), Mar1/89.
Chenopodium murale: Vancouver (CDA), Mar1/89.
Chenopodium quinoa: Vancouver (CDA), Mar1/89.
Cyclamen persicum: Vancouver, Jun11/88.
Davidia involucrata: Vancouver (UBC), Jun14/88.
Nicotiana clevelandii: Vancouver (CDA), Jan15/89.
Nicotiana debneyi: Vancouver (UBC), Feb20/89.
Potentilla alba: Vancouver (UBC), Apr15/88.
STAPHYLEAE (Koch 1854), RHOPALOSIPHONINUS
Abelia x grandiflora ‘Select’: Vancouver (UBC), Feb24/88.
Akebia quinata: Vancouver (UBC), Jun14/88.
Alstroemeria chilensis: Vancouver (UBC), Feb24/88.
Anthriscus cerefolium : Vancouver (CDA), Mar3/89.
Apium graveolens: Vancouver (CDA), Jan26/89.
Artemisia stelleriana: Vancouver (UBC), Feb24/88.
Arum pictum: Vancouver (UBC), Feb24/88.
Aucuba japonica var. borealis: Vancouver (UBC), Feb24/88.
Baccharis magellanica: Vancouver (UBC), Feb24/88.
Bergenia stracheyi: Vancouver (UBC), Feb24/88.
Campanula punctata: Vancouver (UBC), Jan5/89.
Campanula raddeana: Vancouver (UBC), Feb14/89.
Cephalaria gigantea: Vancouver (UBC), Feb24/88.
Cotyledon orbiculata: Vancouver (UBC), Feb24/88.
Dianthus giganteus ssp. banaticus: Vancouver (UBC), Jan5/89.
Dichelostemma volubile: Vancouver (UBC), Feb24/88.
Draba lindensii: Vancouver (UBC), Feb24/88.
Eucomis bicolor: Vancouver (UBC), Jan5/89.
Euonymus fortunei var. radicans: Vancouver (UBC), Feb14/89.
Glaucium corniculatum: Vancouver (UBC), Feb24/88.
Hebe ‘Quick Silver’: Vancouver (UBC), Feb24/88.
Helleborus orientalis: Vancouver (UBC), Feb24/88.
Hesperis matronalis: Vancouver (UBC), Mar21/88, Apr7/88.
Iris aucheri: Vancouver (UBC), Feb24/88.
Iris warleyensis: Vancouver (UBC), Feb24/88.
Lapeirousia anceps: Vancouver (UBC), Feb24/88.
Lavatera cachemiriana: Vancouver (UBC), Feb24/88.
Luetkea pectinata: Vancouver (UBC), Feb14/89.
Notholirion bulbiferum: Vancouver (UBC), Feb24/88.
Penstemon procerus var. tolmiei: Vancouver (UBC), Feb14/89.
Phoenicaulis cheiranthoides: Vancouver (UBC), Jan5/89.
Polemonium elegans: Vancouver (UBC), Jan5/89.
Ribes fasciculatum var. chinense: Vancouver (UBC), Feb24/88.
Romulea ramiflora: Vancouver (UBC), Feb24/88.
Scrophularia aquatica ‘Variegata’: Vancouver (UBC), Feb24/88.
Tellima grandiflora: Vancouver (UBC), Feb24/88.
Tellima grandiflora ‘Purpurea’: Vancouver (UBC), Feb24/88.
87
88 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), Sept. 30, 1989
STELLARIAE Theobald 1913, MACROSIPHUM
Chenopodium murale: Vancouver (CDA), Mar2/89.
Chenopodium quinoa: Vancouver (CDA), Feb20/89.
Cucumis sativus ‘Straight Eight’: Vancouver (CDA), Feb20/89.
Verbena ‘Ideal Florist’: Vancouver (CDA), Mar1/89.
TENUICAUDA Bartholomew 1932, MACROSIPHUM
Urtica dioica: Ladner, Jun6/81, Jul14/81.
Urtica dioica ssp. gracilis var. lyallii: Rosdale, Aug10/88.
TREMULAE (Linnaeus 1761), ASIPHUM
Picea glauca: Prince George, Sep28/88.
Pseudotsuga menziesii: Nelson, Aug21/87.
TRIRHODUS (Walker 1849), LONGICAUDUS
Aquilegia x hybrida ‘Dragonfly Mix’: Vancouver (UBC), Nov22/88.
VARIABILIS Richards 1961, BOERNERINA
Alnus viridis ssp. sinuata: Vancouver (UBC), Jul11/88.
XYLOSTEI (de Geer 1773), PROCIPHILUS
Pseudotsuga menziesii: Nelson, Aug21/87.
ACKNOWLEDGEMENTS
We wish to thank Dr. A.G. Robinson, University of Manitoba, Winnipeg, Manitoba, Dr.
R.L. Blackman, British Museum (Natural History), London, England and Dr. D. Voegtlin,
Illinois Natural History Survey, Champaign, Illinois for valuable aid and advice in identifica-
tion.
REFERENCES
Addicott, J.F. 1981. Synonymy of Aphis heraclella Davis 1919 with Aphis helianthi Monell 1879 (Homoptera:
Aphididae). Canad. Ent. 113:167-169.
Cook, E.F. 1984. Glabromyzus and Utamphorophora (Homoptera: Aphididae) species of North America. Ann.
Entomol. Soc. Am. 77:705-711.
Eastop, V.E, and D. Hille Ris Lambers. 1976. Survey of the world’s aphids. Dr. W. Junk b.v., Publisher, The
Hague.
Forbes, A.R. and C.K. Chan. 1988. The aphids (Homoptera: Aphididae) of British Columbia. 18. Further
additions. J. ent. Soc. Brit. Columbia 85:87-97.
Forbes, A.R. and C.K. Chan. 1987. The aphids (Homoptera: Aphididae) of British Columbia. 16. Further
additions. J. ent. Soc. Brit. Columbia 84: 66-72.
Forbes, A.R., and C.K. Chan. 1986a. The aphids (Homoptera: Aphididae) of British Columbia. 15. Further
additions. J. ent. Soc. Brit. Columbia 83:70-73.
Forbes, A.R., and C.K. Chan. 1986b. The aphids (Homoptera: Aphididae) of British Columbia. 14. Further
additions. J. ent. Soc. Brit. Columbia 83:66-69.
Forbes, A.R., and C.K. Chan. 1985. The aphids (Homoptera: Aphididae) of British Columbia. 13. Further
additions. J. ent. Soc. Brit. Columbia 82:56-58.
Forbes, A.R., and C.K. Chan. 1984. The aphids (Homoptera: Aphididae) of British Columbia. 12. Further
additions. J. ent. Soc. Brit. Columbia 81:72-75.
Forbes, A.R., and C.K. Chan. 1983. The aphids (Homoptera: Aphididae) of British Columbia. 11. Further
additions. J. ent. Soc. Brit. Columbia 80:51-53.
Forbes, A.R., and C.K. Chan. 1981. The aphids (Homoptera: Aphididae) of British Columbia. 9. Further additions.
J. ent. Soc. Brit. Columbia 78:53-54.
Forbes, A.R., and C.K. Chan. 1980. The aphids (Homoptera: Aphididae) of British Columbia. 8. Further additions
and corrections. J. ent. Soc. Brit. Columbia 77:38-42.
Forbes, A.R., and C.K. Chan. 1978. The aphids (Homoptera: Aphididae) of British Columbia. 6. Further additions.
J. ent. Soc. Brit. Columbia 75:47-52.
Forbes, A.R., and C.K. Chan. 1976. The aphids (Homoptera: Aphididae) of British Columbia. 4. Further additions
and corrections. J. ent. Soc. Brit. Columbia 73:57-63.
Forbes, A.R., C.K. Chan and R.G. Foottit. 1982. The aphids (Homoptera: Aphididae) of British Columbia. 10.
Further additions. J. ent. Soc. Brit. Columbia 79:75-78.
Forbes, A.R., B.D. Frazer and C.K. Chan. 1974. The aphids (Homoptera: Aphididae) of British Columbia. 3.
Additions and corrections. J. ent. Soc. Brit. Columbia 71:43-49.
Forbes, A.R., B.D. Frazer and H.R. MacCarthy. 1973. The aphids (Homoptera: Aphididae) of British Columbia. 1.
A basic taxonomic list. J. ent. Soc. Brit. Columbia 70:43-57.
J. Entomot Soc. Brrr. COLUMBIA 86 (1989), SEPT. 30, 1989 89
GLOVER’S SILKMOTH, HYALOPHORA GLOVERI
(STRECKER)(LEPIDOPTERA: SATURNIIDAE), NEW TO BRITISH COLUMBIA
ROBERT A. CANNINGS AND C.S. GuPPY
ROYAL BRITISH COLUMBIA MUSEUM
675 BELLEVILLE STREET
VICTORIA, B.C. V8V 1X4
Two rather common species of giant silkmoths of the subfamily Saturniinae (Lepidoptera:
Saturniidae) occur in southern British Columbia. Both species, the Polyphemus Moth
(Antheraea polyphemus [Cramer]) and the Ceanothus Silkmoth (Hyalophora euryalis [Bois-
duval]) are large and spectacular, and evoke comment from anyone who sees them. Both range
northwards to at least the central Cariboo region. Three other striking species of the subfamily
occur in the Peace River district of Alberta, but these moths, the Cecropia Moth (Hyalophora
cecropia [Linnaeus]), the Columbia Silkmoth (H. columbia [S.I. Smith]), and Glover’s
Silkmoth (H. gloveri [Strecker]) have never been reported from British Columbia. Therefore,
it was a Surprise when a specimen of H. gloveri was recently captured and sent to us from the
Peace River district of the province.
A female H. gloveri (Fig. 1) was discovered by Carolyn and Terry Wood and their family on
the northeast shore of Charlie Lake near Fort St. John. The moth was clinging to a branch of a
small aspen tree (Populus tremuloides Michx.) about 2.5 m from the water’s edge on 22 May
1989 at 20:00 h (MDT). The moth’s wings were expanded, but the insect had evidently only
recently emerged; there were fluid stains on the branch below the moth and its red colour faded
to brown as it dried. The cocoon from which the insect had emerged was not found, although a
second, intact one was attached to the branch near the perching moth. This cocoon is 5 x 2.5 x
2.5 cm. According to Carolyn Wood (in litt. 26 May 1989) none of the local residents, when
questioned, had ever seen a similar moth in the area before.
Figure 1. Hyalophora gloveri (Strecker), female. Charlie Lake, Fort St. John, B.C., 22 May 1989.
90 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
H. gloveri larvae have been recorded feeding on silverberry (Eleagnus argentea Pursh) and
willows (Salix spp.) in Canada. In the United States the species has been reared on willows,
alder (Alnus spp.) wild currant (Ribes spp.), chokecherry (Prunus virginiana L.), and
buffaloberry (Shepherdia spp.) (Ferguson 1972). The details of larval coloration are appar-
ently geographically variable (Ferguson 1972), but in general the mature larvae are very large,
hairless, green caterpillars. Along both sides of the back the larva has prominent yellow
tubercles with black bristles, and along the sides there are rows of white tubercles with black
bristles. The legs and prolegs are yellow (Packard 1914, plates 8-9).
H. gloveri occurs from the United States-Mexican border north along the Rocky Mountains
to Alberta, and east through southern Saskatchewan to Manitoba (Ferguson 1972). There is a
specimen in the Canadian National Collection (Agriculture Canada, Ottawa) from Hay River,
NWT (D. Lafontaine, pers. comm.). Ferguson (1972) gives the northern limits of the range in
Alberta as about 60 miles northwest of Edmonton, but both H. gloveri and H. columbia have
been collected in the Peace River district of Alberta by E.M. Pike (pers. comm.). In addition,
H. cecropia has been collected at Beaverlodge in the same area (Ferguson 1972). Further
investigation in the Peace River district of British Columbia might reveal populations of H.
columbia and H. cecropia. The former feeds on eastern larch or tamarack (Larix laricina [Du
Roi] K. Koch); the latter eats various broadleaved plants such as Manitoba Maple (Acer
negundo L.), wild cherries (Prunus spp.), and willows (Salix spp.). Discovery of these two
moths in British Columbia, in addition to the present report of H. gloveri, would raise the
province’s silkmoth fauna to five species.
The specimen of H. gloveri is deposited in the collection of the Royal B.C. Museum,
Victoria.
ACKNOWLEDGEMENTS
We thank Carolyn Wood (Fort St. John) for sharing her discovery of Glover’s Silkmoth with
us, and donating the specimen to the RBCM. Don Lafontaine (Biosystematics Research
Centre, Agriculture Canada, Ottawa) provided data from the Canadian National Collection,
and Ted Pike (Calgary) contributed information on silkmoths from the Peace River district of
Alberta.
REFERENCES
Ferguson, D.C. 1972. The moths of America north of Mexico. Fascicle 20.2B Bombycoidea, Saturniidae (Part).
E.W. Classey Ltd. and R.B.C. Publications Inc., London.
Packard, A.S. 1914. Monograph of the Bombycine moths of North America. Part III. Families Ceratocampidae
(exclusive of Ceratocampinae), Saturniidae, Hemileucidae, and Brahmaeidae. Memoirs of the Natural
Academy of Sciences 12:1-516.
J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989 91
AN ASIAN HORNET, VESPA SIMILLIMA XANTHOPTERA (HYMENOPTERA:
VESPIDAE) IN NORTH AMERICA
RoBERT A. CANNINGS
ROYAL BRITISH COLUMBIA MUSEUM
675 BELLEVILLE STREET
VicroriA, B.C. V3V 1X4
While examining wasps in the Royal B.C. Museum’s collection, I came across a large
specimen standing under the name Vespa crabro L., the European Hornet. The label indicated
that the insect had been collected by Mr. A. Rumsby at Shawnigan Lake, B.C., just north of
Victoria, in August 1977. Wanting to know more about the circumstances surrounding the
capture, I contacted him.
According to Mr. Rumsby, the hornet had been seen flying around raspberry bushes in his
garden for two days before it ws collected. Because of its notable size the specimen was
considered unusual and was brought to Dr. Robert Carcasson, then Curator of Entomology at
this museum, who identified it as Vespa crabro. I was not so sure. The specimen did not have
the bold yellow and brown abdominal pattern of V.c. germana, the subspecies introduced and
established in eastern North America (Akre et al. 1980); rather it was a uniform golden-brown
colour. This eliminated the possibility of the wasp having arrived in British Columbia from
eastern North America; nevertheless, perhaps it was a member of one of the other subspecies
that range as far east in Asia as Japan.
After considerable sleuthing by several entomologists, the specimen was finally identified
as a queen of a different species, Vespa simillima xanthoptera Cameron, a taxon found in the
Japanese archipelago south of Hokkaido. The nominate subspecies occurs in Hokkaido,
Korea, and the southeastern U.S.S.R. (R.S. Jacobson, in litt.). This is the first record of the
species in North America.
Ships carrying lumber from Canada to Japan regularly call at Cowichan Bay, 10 km due
north of Shawnigan Lake. Probably this specimen or its ancestors arrived from Japan on such
transport; the fact that it was a queen flying late in the summer suggests that a colony may have
developed in the area. Thus, it is possible that a population of these hornets occurred, at least at
one time, near Shawnigan Lake, although in the eleven years since the capture of the specimen,
no others have been reported.
ACKNOWLEDGEMENTS
I thank Mr. A. Rumsby of Shawnigan Lake, B.C. for collecting the hornet and providing
information on its capture, and Dr. Albert Finnamore, Provincial Museum of Alberta,
Edmonton, for his interest in the problem and his help in the identification of the specimen. Dr.
Roger Akre, Washington State University, Pullman, also examined the hornet, and criticized
the manuscript. Dr. Robert Jacobson, East Carolina University, Greenville, N.C., made the
identification.
REFERENCES
Akre, R.D., A. Greene, J.F. MacDonald, P.J. Landolt, and H.G. Davis. 1980. Yellowjackets of America north of
Mexico. U.S. Department of Agriculture, Agriculture Handbook No. 552. 102 pp.
92 J. ENTOMOL Soc. Brit. COLUMBIA 86 (1989), SEPT. 30, 1989
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Journal
of the
Entomological Society
of British Columbia
Volume 87 Issued Deseo 1990 ,» ISSN #0071-0733
Rosert A, CANNINGS
1979
KSB = Entomological Society
of British Columbia
COVER: The larva of the widespread western dragonfly Sympetrum madidum (Hagen) was
first described by Rob Cannings from specimens he collected in Victoria and the Chilcotin
(see Pan-Pacific Entomologist 57(2):341—346, 1981). The species lives in shallow ponds,
often those that dry up in summer. It ranges from the Northwest Territories south through
British Columbia to California and east to Manitoba and Missouri. The adults of the genus
Sympetrum are a common sight in British Columbia from May through October, but are
especially evident in the late summer and fall. Most are reddish; $. madidum can be
identified by its white thoracic stripes and the venation of its orange-tinged wings. The pen
and ink drawing is by Rob Cannings.
Designed, typeset and printed by
Printing & Duplicating Services
University of Victoria, Victoria, B.C. Canada
on 60 Ib. Halopaque Vellum Recycled Paper.
Cover printed on Aegean Blue Mayfair.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Journal
of the
Entomological Society
of British Columbia
Volume 87 Issued December 1990 ISSN #0071-0733
Directors of the Entomological Society of British Columbia, 1990-91 ................. 2
Dang, PT: and D.J. Parker. First Records of Enarmonia formosana (Scopoli) in
INorthAmerica (Lepidoptera: Tortricidae).......2.6. 6<.ees see es Hees vee eee eens ee 3
Wigle, M.J. and H.V. Thommasen. Ephemeroptera of the Bella Coola and
Owikeno Lake watersheds, British Columbia Central Coast................20.005. 7
Heath, R. and R.I. Alfaro. Growth response in a Douglas fir/lodgepole pine stand after
thinning of lodgepole pine by the mountain pine beetle: A case study .............. 16
Harris, L.J., R.I. Alfaro and J.H. Borden. Role of needles in close-range host selection
bythe white pine: weevil on’ Sitka spruce ........ 062.40. UeeesteeeseusGuesataes 22
Sheppard, D.H., J.H. Myers, S. Fitzpatrick and H. Gerber. Efficacy of deltamethrin and
Bacillus thuringiensis Berliner spp. kurstaki on larvae of winter moth, Operophtera
brumata (L.) (Lepidoptera: Geometridae) attacking blueberry in the Lower
Wamiana.of British Columbia? .2.00-0de%64 6 bo.09 ba es 55 ¥en a ees ewe Epes 25
Shore, T.L. Recommendations for sampling and extracting the eggs of the western
hemlock looper, Lambdina fiscellaria lugubrosa, (Lepidoptera: Geometridae)........ 30
Belton, E.M. and P. Belton. A review of mosquito collecting in the Yukon ............ 35
Vernon, R.S. and D.R. Gillespie. Response of Frankliniella occidentalis (Thysanoptera:
Thripidae) and Trialeurodes vaporariorum (Homoptera: Aleyrodidae) to fluorescent
frapsamaicucummber ereenhouse . . 2. cc. ows Sees ae ee one ee ee dae Pe ee 38
Michaud, J.P Observations on the biology of the bronze flea beetle Altica tombacina
(Coleoptera: Chrysomelidae) in British Columbia................ 0.0000. e ee eee 4l
Frazer, B.D. and R.R. McGregor. A rapid method of sampling for aphids on
RIRAW DERE Se Get reed ara tow hate Slaioryntenl e ecanten ) otic aa seg Ae Sea ace oe 50
Mohammad, A.B. and M.T. AliNiazee. Toxicity of foliar residues of phosmet to the
apple maggot, Rhagoletis pomonella (Diptera: Tephritidae) ..................205- 3)
Raworth, D.A. Predators associated with the twospotted spider mite, 7etranychus urticae,
on strawberry at Abbotsford, B.C., and development of non-chemical mite control... .59
Kovacs, E. and J.A. McLean. Notes on the longevity, fecundity and development of
Pissodes terminalis Hopping (Coleoptera: Curculionidae) in the Interior of British
Ceniinbiay Canada. 2.0 etic ss cdercane, hen eae -e ed Se tee Qe te note eke suies maa anes 68
Gerber, H.S. Note on the occurrence of Paravespula germanica (Hymenoptera: Vespidae)
wa-the Lower Fraser Valley of British Columbia... ....... 0.005... -.200.00 000 13
Kovacs, E. and J.A. McLean. Emergence patterns of terminal weevils (Coleoptera:
Curculionidae) and their parasitoids from lodgepole pine in the Interior of British
POumMolds CANaGa ak oe Gs a eee ts epee chin is th nas, ance we eae iD
Roland, J. and S. Szeto. Compatibility of the winter moth parasitoid Cyzenis albicans
(Tachinidae) with pesticide use in the cultivation of blueberries in the Fraser Valley . . .79
Cossentine, J.E., FL. Banham and L.B. Jensen. Efficacy of the nematode, Heterorhabditis
heliothidis (Rhabditida: Heterorhabditidae) against the peachtree borer, Synanthedon
exttiosa. izepidoptera, Sésiidae) in peach theeS .< 644... on os ese ee Odo e sce 82
Marshall, V.G., G.M. Shrimpton and J.P. Battigelli. A preliminary survey of Collembola
MMIOLeSt uMtseries Of Britisa Columbia .6 <0 pecs. se aa ds ssn ee ei ose ees ewe: 85
EL SIRI8 1) SO Oa SN ae ene acd em Saal ere 90
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
DIRECTORS OF THE ENTOMOLOGICAL SOCIETY
OF BRITISH COLUMBIA FOR 1990-91
President
Joan Cossentine
Agriculture Canada, Summerland
President-Elect
Bob Vernon
Agriculture Canada, Vancouver
Past-President
David Raworth
Agriculture Canada, Vancouver
Secretary-Treasurer
Kathy Millar
Duncan
Editorial Committee (Journal)
R. Ring (Editor) H.R. MacCarthy D. Raworth
Editor (Boreus )
Rob Cannings
Royal B.C. Museum
Directors
T. Danyk (1st) G. Judd (ist) J. Troubridge (ist)
S. Fitzpatrick (2nd) T. Shore (2nd)
Honorary Auditor
Chris Guppy
Regional Director of National Society
Bob Vernon
Agriculture Canada, Vancouver
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 3
First records of Enarmonia formosana (Scopoli) in
North America (Lepidoptera: Tortricidae)
P.T. DANG and D.J. PARKER
FORESTRY CANADA
C/O BIOSYSTEMATICS RESEARCH CENTRE
AGRICULTURE CANADA, OTTAWA, ONTARIO K1A 0C8
& PLANT PROTECTION DIVISION
AGRICULTURE CANADA, OTTAWA, ONTARIO KIA 0C6
ABSTRACT
Enarmonia formosana (Scopoli), a widespread Palaearctic species, was recently found
infesting cherry trees in the Richmond area of British Columbia, Canada. Descriptions,
illustrations of male and female genitalia, and a photograph of an adult, are provided to
help identify the species in North America.
INTRODUCTION
In May 1989, at the request of a homeowner in Richmond, B.C., Agriculture Canada
inspectors were asked to look at some cherry trees exhibiting symptoms of yellowing
foliage and bark damage that included cankers, gumosis and frass. Larval and adult
specimens were collected from the site and submitted for identification. Other specimens
were submitted from cherry trees exhibiting similar symptoms in Surrey and Vancouver.
In the early spring of 1990, a series of adults emerged in the laboratory from infested
cherry logs that were collected at Surrey in 1989. Enarmonia formosana (Scopoli), the
cherry bark tortrix, was positively identified based on detailed examinations of these
specimens. E. formosana specimens from France were also examined to further support
this identification. It is believed that E. formosana has been in the Richmond area for
some time, judging from the size of lesions on the host trees caused by repeated infesta-
tions of larvae, and from the large number of adults caught in pheromone traps set in
these areas during the summer of 1990. The description, illustrations, photograph, and
review of biological aspects of this species, provided in the present article, will help
researchers to recognize and identify the pest. This information will be particularly
useful in survey, monitoring and control programs for this species in Vancouver and
neighbouring areas. Various morphological aspects of the species, including illustra-
tions and/or photographs, can also be found in Benander (1950), Bradley et al. (1979),
Graaf Bentinck and Diakonoff (1968), Hannemann (1961), Kennel (1921), Kuznetsov
(1978), and Pierce and Metcalfe (1922). All specimens studied are deposited in the
Canadian National Collection in Ottawa.
DIAGNOSTIC FEATURES
Description.
E. formosana can be recognized by the intricately well-defined colours and patterns of
the forewing and its distinctive genitalia (Figs. 1-4). Specimens collected in Richmond
are darkly pigmented, almost black, with silver and golden-brown markings. There is
little variation or sexual dimorphism in this species.
Head. Head black with blue tinge dorsally, creamy-yellow posteriorly; frons black;
antenna black dorsally, creamy-yellow ventrally; labial palpus mostly dark blue except
for basal segments, median transverse band on segment 3 and ventral and mesal sides of
palpus paler, creamy-yellow.
Thorax (Fig. 1). Notum black with narrow golden-brown cross band; tegula black,
golden brown basally and distally; pleural area bluish gray. Fore wing: length 7-8 mm;
ground colour black; basal third black, distinctly mottled with small irregular silvery-
white to yellow patches forming irregular concentric arching bands; median cross band
4 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
1
arched toward wing apex, extending from basal third of costa to center of wing and to
middle of posterior wing margin, mostly silvery, with narrow creamy-yellow borders,
portion from costa to vein Rs golden-brown, surrounded with black, silvery and creamy-
yellow or golden-brown rings respectively; tornal eye spot conspicuous, about !/2 as wide
as termen, outer ring narrow golden-brown, inner ring wider silvery, center large with
eight alternating black and golden-brown longitudinal dashes; costal strigulae well
defined, extending from basal 3/s to apex, and consisting of five shiny white oblique
comma-shaped streaks separated by black areas; three longitudinal bands successively
of golden-brown, silvery and golden-brown located along areas immediately posterad
and basad of these streaks. Hind wing black. Legs banded, formed by combination of
two contrasting colours: creamy-white on ventral side, both ends of each segment, tibial
spurs and median area of front tibia; black on other areas.
Abdomen. Black dorsally, creamy-white ventrally.
Male genitalia (Fig. 2). Uncus well developed, fleshy and stout, bearing numerous
slender setae; socius large, triangular, fused to uncus and tegumen and attached to
ventral side of tegumen, bearing numerous long and slender setae. Gnathos weak, lightly
sclerotized. Transtilla absent. Tegumen longer than basal width, horseshoe-shaped.
Valva slender, gently arched posteriorly, finger-shaped, distal end broadly and deeply
grooved forming bifid apex with ventral part bearing dense setae and dorsal part bearing
single conical stout seta. Aedeagus cylindrical, broadly enlarged basally; cornutus
absent.
Female genitalia (Figs. 3A—B). Bursa copulatrix oval, densely reticulate; signum well
developed and sclerotized, nearly circular with large, internal, triangular, blade-like
ridge; area anterad and ventrad of ductus bursa lightly sclerotized. Antrum small, lightly
sclerotized. Pleural areas immediately laterad of antrum with pair of small rectangular
sclerites. Abdominal tergite 9 spiculate.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 D
S.
0 So pe
8 00 >
99,2.29,
20092000 6,0
A) ee
1/2mm
Figs. 1-4, morphological aspects of E. formosana: 1. dorsal aspect of adult d ; 2. ventral aspect of
male genitalia with partially spread valvae; 3. lateral aspect of distal portion of female genitalia;
4. ventral aspect of female genitalia.
6 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
REMARKS
The fore wing markings, particularly the tornal eye spot and the well-defined costal
strigulae of Enarmonia formosana, resemble those of a number of nearctic Cydia
species. The fore wings of specimens of Eucosmomorpha albersana (Hiibner), an
introduced palaearctic species belonging to the Enarmonini, collected in Michigan,
U.S.A. (Miller 1983) and Saskatchewan, Canada (CNC) also show markings similar to E.
formosana. However, E. formosana can be easily distinguished from the above-
mentioned species on the basis of its rather unique structures of the male and female
genitalia.
DISTRIBUTION AND BIOLOGY
The cherry bark tortrix occurs throughout Europe, temperate Asia and North Africa.
The larvae feed on the bark and sapwood of a variety of plants of the family Rosaceae
including Cydonia (quince), Malus (apple), Prunus (almond, apricot, cherry, nectarine,
peach and plum), Pyracantha (firethorne), Pyrus (pear) and Sorbus (mountain ash). The
larvae feed within bark tissue and may extend damage into the cambium. Attacks are
more obvious on older or previously injured trees. Detailed descriptions of the biology
and life history are outlined in Balachowsky (1966) and Alford (1984). The Plant
Protection Division of Agriculture Canada is in the process of surveying the Lower
Mainland of British Columbia to determine the current distribution of cherry bark
tortrix.
ACKNOWLEDGEMENTS
We thank Shane Sela, Owen Croy, Ed Ross and Chris Yeoh, Agriculture Inspection
Directorate, Agriculture Canada for collection of specimens and providing information
from British Columbia; J. Chambon, INRA, France, for providing specimens of
Enarmonia formosana from Europe for comparison; Stephen Aitken for illustrating the
male and female genitalia and Bill Lukey for taking the photograph of the adult.
LITERATURE CITED
Alford, D.V. 1984. A colour atlas of fruit pests. Wolfe Publ. Ltd., Glasgow. 320 pp.
Balachowsky, A.S. 1966. Entomologie appliquée a1’ agriculture. Tome II. Lépidoptéres, Masson et Cie., Paris.
1057 pp.
Bradley, J.D., W.G. Tremewan and A. Smith. 1979. British Tortricoid moths. Tortricidae: Olethreutinae. The
Ray Society, London. 320 pp.
Benander, P. 1950. Fjarilar. Lepidoptera IT. Smafjarilar. Microlepidoptera. Andra familjegruppen Vecklaref-
jarilar. Tortricina. Svensk Insektfauna 10, 173 pp., 9 pltes.
Graff Bentinck, G.A. and A. Diakonoff. 1968. De Nederlandse Bladrollers (Tortricidae). Een Geillustreerd
Overzicht. Monogr. Nederland. Entomol. Vereen. 3:1—201.
Hannemann, H.J. 1961. Kleinschmetterlinge oder Microlepidoptera I. Die Wickler (s. str.) (Tortricidae). Die
Tierwelt Deutsche. 48:1-233.
Kennel, J.V. 1921. Die Palaearktischen Tortriciden. Eine monographische Darstellung. Zoologica 54:1-742
(plts. 1-24).
Kuznetsov, V.I. 1978. Family Tortricidae (Olethreutidae, Cochylidae)—Tortricid moths. Pp. 279-967. In
Medvedev, G.S. (Ed.). Keys to the insects of the European Part of the USSR. Vol. IV Lepidoptera Part 1.
Acad. Nauk SSSR Zool. Inst. Leningrad 1978. Translated from Russian. U.S. Dept. Agric. & Natl. Sci.
Foundation. Washington, D.C. 1987. 991 pp.
Miller, W.E. Eucosmomorpha albersana (Hiibner) a palaearctic species, collected in North Amercia
(Tortricidae, Grapholitini). J. Lep. Soc. 37(1):88-89.
Pierce, EN. and J.W. Metcalfe. 1922. The genitalia of the group Tortricidae of the Lepidoptera of the British
Islands. Oundle, Northands, Warmington. 101 pp. 34 plts.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 7
Ephemeroptera of the Bella Coola and Owikeno Lake
watersheds, British Columbia Central Coast
MICHAEL J. WIGLE
BOX 643, BELLA COOLA, B.C. VOT 1C0
AND
HARVEY V. THOMMASEN, M.D.
BOX 220, BELLA COOLA, B.C. VOT 1C0
ABSTRACT
Collection records of Ephemeroptera from the Bella Coola and Owikeno Lake watersheds
on the British Columbia central coast are presented for the first time. Twenty-six species,
representing eleven genera and five families, are listed along with ecological notes.
INTRODUCTION
The Ephemeroptera (Mayflies) of the British Columbia central coast have not yet been
characterized. No published collection records exist for this area (Scudder 1975).
Between June 1987 and August 1990, one of the authors (M.W.) collected and identified
at least 26 different Ephemeroptera species from the Bella Coola and Owikeno Lake
watersheds. This report summarizes the findings.
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Fig. 1. Pacific Coast of British Columbia showing the location of the Bella Coola and Owikeno
Lake watershed areas.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
THE STUDY AREA
Mayfly (Ephemeroptera) nymphs and adults were collected from the Bella Coola and
Owikeno Lake drainage systems (Fig. 1). These watersheds are situated in the rugged
Coast Mountains of British Columbia between latitudes 51°30’ and 52°30’ N, and
longitudes 125°15’ and 127°15' W. This area of the British Columbia central coast
features numerous fjords, channels, and mountains which rise sharply from valley
bottoms at less than 150 m elevation to peaks exceeding 2,400 m in less than 4 km. Mean
annual precipitation exceeds 250 cm. The predominant biogeoclimatic zones in the two
watersheds are Coast Western Hemlock at low elevations, Mountain Hemlock at sub-
alpine levels, and Alpine Tundra at the highest elevations (Baer 1973, Leaney and Morris
1981). Highway 20 connects Bella Coola, at the head of North Bentinck Arm with
Williams Lake, 480 km to the east but Owikeno Lake is accessible only by boat, plane, or
helicopter. Logging roads have been built in many of the main valleys opening into the
Bella Coola valley, and into Owikeno Lake, and these provide some access into the
terrain.
The Bella Coola River system drains an area of approximately 6,500 km?, whereas
the Owikeno Lake system drains a slightly smaller area (Leaney and Morris 1981). Fig. 2
and 3 show the primary collection sites. There were nine primary collection sites in the
Bella Coola watershed, namely: Thorsen Creek, Snootli Creek, Sato Creek, Lower Fish
Creek, Salloomt River, Noosgulch River, Nusatsum River, the Atnarko River and
spawning channel, and Leech Lake. Sato Creek and Lower Fish Creek are two small
creeks located in Hagensborg. There were nine primary collection sites in the Owikeno
Lake watershed, namely: Dallery Creek, Ashlum Creek (two sites), Neechanz River, the
shores of Owikeno Lake near Genesee Creek, Sheemahant River, Washwash River, and
Inziana River (two sites) (Fig. 3.). Benthic sampling for mayfly nymphs and aerial
sampling for adults was confined to the lower reaches of the streams and rivers except for
the Nusatsum River sampling site located 25 km south of Highway 20 along a logging
road. All collection sites were below 500 m except for the Nusatsum River site which was
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J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Tzeo River
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Fig. 3. Owikeno Lake watershed showing the main collection sites.
at approximately 900 m elevation. Most collection sites featured relatively shallow, clear,
moderate to fast flowing water with gravel and cobble substrate. The Atnarko River
spawning channel has slow to moderate flowing, clear water; Leech Lake is a small, still
kettle pond; the Sheemahant River is a moderate to fast flowing river with high glacial silt
load. All creeks and rivers sampled are glacier fed, except for the Atnarko River and
Leech Lake. The former flows from several large lakes; the latter is fed from spring or
ground water (Hynes 1970).
METHODS
From June 1987 to August 1990 mayfiy (Ephemeroptera) nymphs and adults were
collected from the Owikeno Lake, and Bella Coola River areas. Streams with noticeable
flows were sampled using a Surber-type benthic sampler with a mesh size of 1.0 mm.
Ponds, lakes and backwater sloughs were sampled with a plankton tow net through
submerged vegetation of the littoral zone. Adults were sampled by sweeps through aerial
mating swarms, sweeps through stream-side vegetation, and some were also collected by
handpicking them from the streamside vegetation (usually females) or cobble and rubble
stream banks (usually subimago males and females) (Pennak 1978). Hand constructed
emergence traps made with 1.0 mm sized mesh were used from May 1990 to August 1990
in Sato Creek, Lower Fish Creek, and Salloomt Creek collection sites. Mature nymphs
from collection sites were introduced into the emergence traps. Traps were checked
regularly for emerging subimagos, these were collected in wide mouth jars and reared to
imagos at home. Water temperatures were frequently recorded at collection sites with a
field thermometer. All specimens were identified with the aid of a Kyowa SDZ-TR
stereomicroscope. Articles and keys used for identification were those of Allen and
Edmunds (1962, 1963, 1965), Day (1956), Edmunds et al. (1976), Edmunds and Allen
10 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
(1964), Jensen (1966), Lehmkuhl (1968, 1970a, 1970b, 1971, 1979), McCafferty (1983),
Morihara and McCafferty (1979) and Traver (1935). Existing geographic ranges were
determined primarily from Allen (1980), Jensen (1966), and Scudder (1975). The
specimens were stored in 70% isopropyl alcohol and were given to the Royal British
Columbia Museum, Victoria, B.C. for verification and preservation.
SPECIES LIST
Siphlonuridae
Ameletus validus McDunnough
Washwash River, approximately 100 meters upstream from the mouth at Owikeno Lake,
7-IX-1989, mature nymph. Water temperature was 10°C. Mature specimens were also
collected from the Atnarko River spawning channel in October of 1990. Typical habitat
consists of moderate velocity riffle runs with small and large gravel and cobble substrate.
These findings extend the known distribution of A. validus in British Columbia north-
westerly from the Penticton area.
Ameletus species
Snootli Creek, near the Snootli Creek Hatchery outflow creek, 17-II-1989, mature
nymph. Specimens collected have been quite large, 16-18 mm long. Habitat consists of
moderate velocity riffle runs with gravel and cobble substrate.
Baetidae
Baetis tricaudatus Dodds
Atnarko River spawning channel, 12-II-1989, mature nymphs. Mature nymphs have also
been collected from February to May in the main Atnarko River and in Thorsen Creek.
Subimago and imagos were collected in March 1990 in the Atnarko River. Mature
nymphs and adults were collected from the Owikeno Lake area in September 1989.
Emergence of subimagos was noted, 13-[X-1989, at the mouth of Dallery Creek. Water
temperature was 10°C. These subimagos were held to maturity for identification. Typical
habitat consists of moderate flow riffle runs with gravel and cobble substrate. These
findings extend the known range of B. tricaudatus in British Columbia northwesterly
from the Salmon Arm area.
Baetis bicaudatus Dodds
Washwash River, approximately 100 meters from the mouth at Owikeno Lake, 23-
IX-1989, mature nymphs. Water temperature was 10°C. Mature nymphs were also found
in other Owikeno Lake streams throughout September 1989, and the Bella Coola
watershed, including the Upper Nusatsum River collection site, 15-VII-1989. Typical
habitat consists of moderate flow riffle runs with gravel and cobble substrate. These
findings extend the known distribution of B. bicaudatus in British Columbia north-
westerly from the Lillooet area.
Callibaetis nigritus Banks
Leech Lake, 10-IV-1989, mature male nymph and four male imagos. The mature nymph
was collected in submerged weed habitat of the lake shore. The imagos were observed in
a mating swarm over the entire one hectare lake surface. Swarm height was between 0.3
to 1.5 meters above the surface. Dragonflies, damselflies, and cutthroat trout were
feeding heavily on spent swarmers and emerging subimagos at this time. Nymphs have
also been found in other slow flow to stagnant ponds in the Bella Coola watershed, e.g.,
Millpond along the Salloomt Road near Hagensborg, and Walker Island beaver pond near
Snootli Park. Nymphs are most plentiful from fall to spring. These findings extend the
known distribution of C. nigritus west from the Springhouse, Chilcotin area.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 11
Heptageniidae
Cinygma integrum Eaton
Dump Creek approximately 300 meters upstream from Highway 20 and 200 meters east
of Thorsen Creek, 8-II-1989, nymph. Nymphs have also been found from May to July in
small feeder creeks near outflows into mainstem creeks and rivers of the Bella Coola
watershed. Water temperatures typically range from 9 to 13°C at these sites. Imago males
and females were collected throughout June and July 1990 at Sato Creek. On clear, warm
evenings, females were observed exhibiting egg depositional behavior. This behavior
consisted of the females hovering between 30 to 100 cm above water, then dropping and
touching their egg covered abdominal tips to the water surface. Two females repeated
this hovering and dropping behavior approximately 30 times before flying vertically
upwards and out of sight. Nymphal habitat is characteristically slow to moderate flow
riffle runs, usually associated with submerged wood and cobble substrate. These findings
extend the known range of C. integrum northerly along the Pacific coast from the Alto
Lake and Mons areas.
Cinygmula uniformis McDunnough
Atnarko River, 22-IV-1990, mature nymphs, male and female subimagos. Subimagos
were reared to imagos. Water temperature was 7°C. Sample area consisted of moderate
flow riffle runs with gravel substrate. The range of this species is extended northwesterly
from the Penticton area.
Cinygmula species
Atnarko River spawning channel, 11-IV-1989, mature nymphs and male and female
subimagos. These specimens vary markedly in size and general body coloration. The
sample area consists of moderate flow riffle runs with gravel substrate.
Epeorus (Ironopsis) grandis McDunnough
Upper Nusatsum River, 1-VII-1989, mature nymphs. Mature nymphs were abundant at
this collection site until mid-July. Mature nymphs have also been collected in the lower
reaches of Thorsen Creek and the Atnarko River spawning channel. Habitat is charac-
teristically moderate to fast flow riffle runs with gravel and cobble substrate. Upper
Nusatsum River, 9-VII-1989 and 15-VII-1989, male and female imagos. The female
imagos were collected on streamside vegetation near midday. The male imagos were
collected from a small mating swarm over a side channel of the Nusatsum River. The
swarm height ranged from 1.5 to 4 meters above the water surface between 1130 to 1500
hours. Water temperature was 11.5°C and weather warm and sunny with cloudy periods.
Winds were negligible. These findings extend the known range of this species north-
westerly from the Hedley, Seton Lake, and Peachland areas of British Columbia.
Epeorus Uron) albertae McDunnough
Atnarko River, approximately 300 meters downstream from Fisheries Pool, 6-VII-1989
and 9-VII-1990, mature nymphs. These specimens were collected from an area of
moderate to fast flow with gravel and cobble substrate. Water temperatures were 16 to
17°C and depth approximately 20 to 40 cm. The range for this species is extended
northwesterly from the Summerland area.
Epeorus (Iron) longimanus Eaton
Thorsen Creek, approximately 200 meters downstream from Highway 20 bridge,
2-VII-1989, mature nymphs. Mature nymphs have also been collected from Nusatsum,
Salloomt, and Noosgulch Rivers throughout July 1989. Typical habitat consists of fast
flow riffles with cobble substrate. A single male subimago was collected on the evening
of 28-V-1990 over Sato Creek. These findings extend the known range of E. longimanus
northerly along the Pacific Coast from the Alta Lake area.
Epeorus ([ron) deceptivus McDunnough
Ashlum Creek approximately 200 meters upstream from the mouth of Owikeno Lake,
8-IX-1989, mature nymphs. Water temperature was 9.5°C. Noosgulch River approx-
12 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
imately 5 kilometers upstream from the mouth at Bella Coola River, 22-VII-1989,
mature nymphs. Specimens have also been collected from the Sheemahant River (12-
[X-1989), Inziana River (19-IX-1989) (Fig. 3), and the Atnarko River spawning channel
(May 1989) (Fig. 1). Habitat is characteristically moderate to fast flow riffle rapids with
gravel and cobble substrate. These findings extend the known range of E. deceptivus in
British Columbia westerly from the Barkerville area.
Epeorus (Ironodes) nitidus Eaton
Sato Creek, approximately 2 km east of Hagensborg, 30-XI-1989, intermediately
developed nymphs. Nymphs were collected in moderate flow, shallow riffles, approx-
imately 10 cm deep, under cobble size rocks of substrate. Water temperature was
approximately 5.5°C. The specimens in this nymphal collection range from light gray-
brown to darker yellow brown (ochrous) to reddish brown. Specimens range in length
from 7 to 10 mm. Wingpads were noticeable but not fully developed. Because of
difficulty in identifying these nymphs to species, additional nymphs were collected from
Sato Creek and Lower Fish Creek on a monthly basis between December 1989 to July
1990. Nymph maturation was characterized by minimal increase in total length, but
progressive development of wingpads. A female subimago was observed emerging at
1500 hours 1-VI-1990 from Lower Fish Creek on a clear, warm day. Water temperature
was 8°C. Additional subimagos were collected from emergence traps between 26- V-1990
and 7-VII-1990 and reared to imagos. E. nitidus has not previously been listed for British
Columbia (Scudder 1975).
Rithrogena hageni Eaton
Salloomt River approximately 1 km upstream from the mouth at the Bella Coola River,
2-VII-1989, single nymph. Additional mature nymphs were collected in July and August
1990. These specimens were collected in moderate to fast riffle runs with gravel and
cobble substrate. These specimens extend the range of R. hageni in British Columbia
northwesterly from Summerland and Steelhead areas.
Rithrogena robusta Dodds
Upper Nusatsum River collection site, 1- VII-1989, mature nymphs. The specimens were
collected from fast flow riffle rapids with gravel cobble and boulder substrate. Water
temperature was 9 to 10°C. Upper Nusatsum River collection site, 15-VII-1989, two male
imagos and two female imagos. A mating swarm consisting of 60 to 70 males and
females in a vertical column 3 to 12 meters above the water surface was observed from
1200 to 1600 hours. Weather was sunny and warm with intermittent clouds. There was no
wind. Water temperature was approximately 11°C. These specimens extend the known
range of R. robusta in British Columbia northwesterly from the Keremeos area.
Leptophlebiidae
Paraleptophlebia debilis Walker
Mill pond approximately one km north on Salloomt Road, 31-VII-1989, male imagos. A
male swarm was observed and collected over a beaver pond shoreline at approximately
2000 hours on aclear evening. They showed a vertical rise and fall of approximately 40 to
50 cm at a height just above vegetation, i.e., 1 to 2.5 meters above ground level. A similar
male swarm was observed near the Walker Island beaver pond near Snootli Creek (14-
VII-1989). Lower Fish Creek, 28-VI-1989, four female imagos and one subimago. These
females were found on streamside vegetation on the underside of leaves. Owikeno Lake
shore, 9-IX-1989, mature nymphs and male imagos. Mature nymphs were collected in
the gravel and cobble shallows of the lake shore near the mouths of creeks and rivers.
Adults were observed in small swarms along the shoreline until mid-morning in shaded
areas. Nymphs have also been found in many of the creeks and rivers in the Bella Coola
watershed. Mature nymphs seem more abundant in the quiet backwaters of creeks and
rivers, whereas the immature nymphs seem to be more abundant in moderate flow riffle
run habitats. These findings extend the known range of P. debilis in British Columbia
northerly along the Pacific coast from the Agassiz and Nicola Creek areas.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 13
Paraleptophlebia temporalis McDunnough
Atnarko River spawning channel, 5-II-1989, nymphs. Specimens were collected in slow
to moderate flow runs with gravel substrates. Sato Creek, 29-V-1990, five female imagos.
Weather was warm and sunny but these female imagos were collected in a heavily shaded
area of the creek between 1600 and 1630 hours. Water temperature was 9°C. The females
were observed exhibiting ovipositing behavior. They would hover 10 to 15 cm over the
water surface and then move in quick up and down motions approximately 15 cm
distances before dropping to the water surface. These female imagos repeated this
sequence several times before they were collected. Collected female imagos had whitish
egg masses protruding from their genital openings. These nymph and imago specimens
extend the known range of P. temporalis in British Columbia northerly along the Pacific
coast from the Alto Lake and Mons areas.
Paraleptophlebia vaciva Eaton
Upper Nusatsum River, 2-VII-1990, three male imagos. These were observed and
collected from a mating swarm located over a logged clearing approximately 75 meters
from the river. Swarm height was between 1.5 to 3 meters above ground level. Weather
was clear, sunny, and warm and the specimens were collected between 1000 to 1200
hours. The known range of P. vaciva is extended northwesterly from Clinton, Mt. Apex,
Hope and Keremeos areas.
Ephemerellidae
Drunella coloradensis Dodds
Upper Nusatsum River collection site, 9-VII-1989, nymphs. Nymphs collected at this
time were generally at an intermediate stage of development with small wing pads and
were approximately 8 to 10 mm long. Mature nymphs found were approximately 12 to 14
mm long. Washwash River approximately 100 meters upstream from the mouth at
Owikeno Lake, 7-IX-1989, mature nymphs, cast and male subimago. All specimens
collected at this time were mature and ranged from 11 to 14 mm long. Typical habitat for
D. coloradensis in these areas consisted of moderate to fast flow riffle runs with gravel
and cobble substrate and 10°C water. The range for this species in British Columbia is
extended along the Pacific coast northerly from the Capilano River area near Vancouver.
Drunella doddsi Needham
Upper Nusatsum River collection site, 30-VII-1989, mature nymphs and subimagos.
Subimagos were observed emerging from a fast flow riffle rapids area at this time.
Mature nymphs collected from this area were observed undergoing ecdysis. Water
temperature was approximately 13 to 14°C. Mature nymphs of D. doddsi have also been
collected from numerous creeks and rivers of moderate to fast flow with clean gravel and
cobble substrates in the Bella Coola watershed. The finding of these specimens fills a gap
between the Kispiox River area and the lower mainland around the Alouette River,
Capilano River and Skagit River areas.
Drunella flavilinea McDunnough
Atnarko River approximately 300 meters downstream from Fisheries Pool, 6-VIII-1989,
one nymph. This single nymph was collected from a moderate flow riffle run habitat with
gravel and cobble substrate. Water temperature was approximately 17°C. At the same site
on 9-VII-1990, mature nymphs were collected in abundance. To date we have had no
success rearing adults in emergence traps. The presence of D. flavilinea in the Atnarko
River may be due to the noticeably warmer water temperature of this river compared to
other creeks and rivers in the Bella Coola watershed (Jensen 1966). The presence of these
specimens in the Bella Coola watershed extends the known range of D. flavilinea in
British Columbia northerly along the Pacific coast.
Drunella grandis ingens McDunnough
Atnarko River spawning channel, April/May 1989, mature nymphs. Specimens have also
been collected from many of the creeks and rivers of the Bella Coola watershed. Typical
14 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
habitat consists of slow to moderate flow associated with gravel substrates or among
submerged vegetation. Nymphs are abundant in these habitats until June, then are
negligible in summer samples except at higher elevations. Immature nymphs were found
in samples from October. The range of this species in British Columbia is extended
northwesterly from Oliver, Summerland, Penticton, and Peachland areas.
Drunella spinifera Needham
Upper Nusatsum River collection site, 9-VII-1989, mature nymphs. Specimens were
collected from moderate to fast flow riffle runs with gravel and cobble substrates
throughout July 1989 at this site. The range of this species in British Columbia is
extended northerly along the Pacific coast from the Alouette River area.
Ephemerella aurivillii Eaton
Atnarko River spawning channel, IV-1989, mature nymphs. Mature nymphs have also
been collected from many other creeks and rivers of the Bella Coola watershed.
Specimens are usually collected from moderate flow riffle runs with gravel and cobble
substrates. Some specimens have been found in submerged weeds in slow to moderate
flow creeks and, in many cases, in association with D. grandis ingens. The finding of E.
aurivillii in the Bella Coola watershed extends the known range northwesterly from the
Cache Creek area. |
Ephemerella inermis McDunnough
Upper Nusatsum River collection site, 15-VH-1989, nymphs. Specimens were collected
from moderate flow riffle runs with gravel and cobble substrates. The finding of E.
inermis in the Bella Coola watershed extends the range of this species in British
Columbia northerly along the Pacific coast from the Alouette River area. Other
specimens have come from the Penticton and Shuswap Lake areas.
Ephemerella infrequens McDunnough
Salloomt River, 15-VII-1990, mature nymphs. Two female imagos were reared in
emergence traps. Water temperature was 10°C. The range of this species in British
Columbia is extended northwesterly from the Seton Lake area.
Serratella tibialis McDunnough
Noosgulch River approximately 300 meters upstream from the mouth at the Bella Coola
River, 13-VIII-1989, mature nymphs. Specimens are typically found in moderate to fast
flow riffle runs with gravel and cobble substrate. Mature specimens of S. tibialis have
also been found in samples taken from creeks and rivers of the Owikeeno Lake
watershed. They were relatively abundant in samples taken until mid-September;
thereafter a decline in numbers collected was noticed. Salloomt River, 26-VII-1990
throughout August 1990, male and female imagos reared in emergence traps. The range
of this species in British Columbia has been extended northerly along the Pacific coast
from the Mosquito Creek area near Vancouver.
DISCUSSION
Twenty-six Ephemeroptera species in eleven genera and five families were collected from
the Bella Coola and Owikeno Lake watersheds in the British Columbia central coast.
This preliminary list for the area represents approximately 25 percent of the known
provincial fauna. The geographic ranges for nine species are extended north along the
British Columbia Pacific coast; for twelve species, they are extended northwesterly; and
for two species are extended westerly. The finding of Drunella doddsi Needham fills in a
gap between the Kispiox River and lower mainland collection sites such as the Capilano
River, Alouette River, and Skagit River. Epeorus (Ironodes) nitidus is recorded for the
first time in British Columbia. This species has been collected in Oregon, U.S.A. (Jensen
1966). Drunella flavilinea and Epeorus albertae were found only in the Atnarko River.
This river is unique in being warmer (summer range of 16 to 18°C) than the vast majority
of rivers and creeks in the central coast (summer range 10 to 14°C). Jensen (1966) had
previously noted that both D. flavilinea and E. albertae occupy the warmer portions of
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 15
streams. The finding of bivoltism for Baetis tricaudatus in the central coast is consistent
with previous reports in other areas (Edmunds et al. 1976). There appears to be two or
possibly three species of the genus Cinygmula indigenous to the area. Mature nymphs of
Cinygmula have been collected in the spring and fall and several of these vary markedly
in size and general body coloration. Hopefully more adult specimens will eventually be
collected or reared in an aquarium or emergence trap to verify this premise. It should be
pointed out that the majority of sampling sites were below 500 meters altitude, and in
moderate to fast flowing glacial streams with gravel and cobble substrate. Future plans
include sampling higher elevation streams, rivers and mountain lakes, and also the
gathering of more seasonal and quantitative information.
ACKNOWLEDGEMENTS
Special thanks to S.G. Cannings (Department of Zoology, University of British Colum-
bia, Vancouver), R.A. Cannings (Entomology Division, Royal B.C. Provincial Mu-
seum, Victoria), and D.M. Lehmkuhl (Department of Zoology, University of Saskatche-
wan, Saskatoon) for reviewing the manuscript, and offering their advice and assistance.
REFERENCES
Allen, R.K. 1980. Geographic distribution and reclassification of the subfamily Ephemerellinae (Ephemerop-
tera: Ephemerellidae). pp. 71-91. in: Advances in Ephemeroptera Biology. Flannagan and Marshall, eds.
Plenum Press, New York.
Allen, R.K. and G.E Edmunds Jr. 1962. A revision of the genus Ephemerella (Ephemeroptera: Ephem-
erellidae). V. The subgenus Drunella in North America. Misc. Publ. Entom. Soc. Amer. 3:147-179.
Allen, R.K. and G.E Edmunds Jr. 1963. A revision of the genus Ephemerella (Ephemeroptera: Ephem-
erellidae). VI. The subgenus Serratella in North America. Ann. Entomol. Soc. Amer. 56:583-600.
Allen, R.K. and G.E Edmunds Jr. 1965. A revision of the genus Ephemerella (Ephemeroptera: Ephem-
erellidae). VII. The subgenus Ephemerella in North America. Misc. Publ. Entoml. Soc. Amer. 4:243-
282.
Baer, A.J. 1973. Bella Coola-Laredo Sound Map Areas, British Columbia. Geological Survey of Canada.
Memoir 372. Department of Energy, Mines, and Resources Canada.
Day, W.C. 1956. Ephemeroptera. /n Aquatic Insects of California, R.L. Unsinger, ed. pp. 79-105. Univ. Calif.
Press, Berkeley.
Edmunds, G.F Jr, and R.K. Allen. 1964. The Rocky Mountain species of Epeorus (Iron) Eaton
(Ephemeroptera-Heptagenidae). J. Kansas Entomol. Society 37:275-288.
Edmunds, G.F Jr., S.L. Jensen and L. Berner. 1976. The Mayflies of North and Central America. Univ. Minn.
Press, Minneapolis.
Hynes, H.B.N. 1970. The Ecology of Running Waters. Liverpool Univ. Press, Liverpool.
Jensen, S.L. 1966. The Mayflies of Idaho (Ephemeroptera). M.S. Thesis (unpubl.). Univ. of Utah, Salt Lake
City.
Leaney, A.J. and S. Morris. 1981. The Bella Coola River Estuary: Status of Environmental Knowledge to 1981.
Special Estuary series No. 10. Fisheries and Oceans Canada. Environment Canada.
Lehmkuhl, D.M. 1968. Observations on the life histories of four species of Epeorus in western Oregon
(Ephemeroptera: Heptageniidae). Pan. Pac. Entomol. 44: 129-137.
Lehmkuhl, D.M. 1970a. The life cycle of Rithrogena morrisoni (Banks) in western Oregon (Ephemeroptera:
Heptageniidae). Pan. Pac. Entomol. 46:124-127.
Lehmkuhl, D.M. 1970b. Observations on the biology of Cinygmula reticulata McDunnough in Oregon
(Ephemeroptera: Heptageniidae). Pan. Pac. Entomol. 46:268—274.
Lehmkuhl, D.M. 1971. Contributions to the biology and taxonomy of the Paraleptophlebia of Oregon
(Ephemeroptera: Leptophlebiidae). Pan. Pac. Entomol. 47:85-93.
Lehmkuhl, D.M. 1979. The North American species of Cinygma (Ephemeroptera: Heptageniidae). Can. Ent.
3:675-680.
McCafferty, W.P. 1983. Aquatic Entomology. Jones and Bartlett Inc. Boston.
Morihara, D.K. and W.P. McCafferty. 1979. The Baetis larva of North America (Ephemeroptera: Baetidae).
Trans. Amer. Entomol. Soc. 105:139-221.
Pennak, R.W. 1978. Ephemeroptera. Jn Freshwater Invertebrates of the United States, 2nd Ed. Wiley and Sons
Inc. New York, pp. 535-550.
Scudder, G.G.E. 1975. An annotated checklist of the Ephemeroptera (Insecta) of British Columbia. Syesis,
8:311-315.
Traver, J.R. 1935. Systematics in the Biology of Mayflies. Comstock Publ. Co. Inc., Ithaca, N.Y.
16 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Growth response in a Douglas-fir/lodgepole pine stand after
thinning of lodgepole pine by the mountain pine beetle:
A case study
RICHARD HEATH
B.C. MINISTRY OF ENVIRONMENT
VANCOUVER ISLAND REGIONAL OFFICE
2569 KENWORTH ROAD, NANAIMO, B.C. V9T 4P7
AND
RENE I. ALFARO
FORESTRY CANADA, PACIFIC AND YUKON REGION
PACIFIC FORESTRY CENTRE, VICTORIA, B.C., CANADA V8Z 1M5
ABSTRACT
Diameter growth response was measured in a mixed stand of lodgepole pine, Pinus
contorta Doug]. ex Loud, and interior Douglas-fir, Pseudotsuga menziesii var glauca
(Beissn.) Franco, in the Cariboo Forest Region of British Columbia, 14 years after an
outbreak of the mountain pine beetle, Dendroctonus ponderosae Hopkins, killed 76% of
the pine. Nearly ali Douglas-fir and a large proportion of the lodgepole pine responded to
the beetle-induced thinning with a diameter growth increase which persisted 14 years
after the infestation. Douglas-fir trees gained an average 1.4 cm or 11.7% in diameter over
the estimated size the trees would have reached in the absence of the thinning effect.
Annual growth rates of Douglas-fir in the post-outbreak period averaged 2% per year
without the beetle-induced thinning and 2.9% after thinning. The surviving lodgepole
pine trees gained an average | cm or 5.4% in diameter over the size the trees would have
reached in the absence of the thinning effect. In the post-outbreak period, annual
diameter growth rates of the pine doubled from 0.4% per year without the thinning, to
0.8% per year with thinning. The thinning response in Douglas-fir was inversely related
to the initial diameter and age of the trees at the start of the infestation but that of pine was
not.
INTRODUCTION
Mixed stands of lodgepole pine, Pinus contorta Dougl. ex Loud, and interior Douglas-
fir, Pseudotsuga menziesii var glauca (Beissn.) Franco, are typical of large areas of the
Cariboo Forest Region of British Columbia (B.C.). Throughout this region, the
mountain pine beetle, Dendroctonus ponderosae Hopkins, kills mature and overmature
lodgepole pine in extensive infestations that last for several years (Safranyik et al. 1974).
A series of outbreaks in many stands in the east-central area of the Region occurred
during the 1970-80 period. For example, an outbreak which began on the Chilcotin
Plateau in 1971/72 continued unabated until 1985, killing approximately 22,000,000 m?
of pine over 1,700,000 ha (Doidge, personal communication) before collapsing after two
extremely cold winters in 1985/86. Most infestations collapsed prior to the depletion of a
highly susceptible host. In mixed stands, because of a selective killing of lodgepole pine,
a thinning or release effect, manifested as an acceleration of the trees’ growth rates, was
expected to occur among the Douglas-fir and the surviving lodgepole pine. Such a release
was demonstrated by Cole and Amman (1980) who detected growth acceleration in
lodgepole pine after each of several beetle infestations. Because the beetles tend to kill
mainly the large diameter lodgepole pine trees in a stand (Craighead 1925, Cole and
Amman 1969, Safranyik et al. 1974), the type of thinning that the beetles cause
correspond to a thinning from above (Smith 1962).
Information on the growth response of interior Douglas-fir and lodgepole pine to
thinning is relatively scanty. Knutson and Tinning (1986) studied the response to
thinning of young Douglas-fir with varying degrees of infection by dwarf mistletoe and
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 17
concluded that trees with no or low infection responded to thinning with a significant
increase in radial growth, while severely infected trees did not. Studying a lodgepole
pine stand in Alberta, which underwent a combination of thinning from above and below,
Johnstone (1982) demonstrated that semi-mature (77-year-old) lodgepole pine responded
well to thinning. Waring and Pitman (1985) concluded that 120-year-old lodgepole pine
responded to thinning and fertilization with increased growth efficiency and vigor, which
in turn decreased the risk of beetle-caused tree mortality.
This paper quantifies the diameter growth response in a mixed Douglas-fir-lodgepole
pine forest 14 years after the start of a mountain pine beetle infestation, which over a
number of years, selectively killed a large proportion of the pine.
MATERIALS AND METHODS
The studies were conducted in an area known as Bull Mtn., about 4 km north of Williams
Lake, B.C. (Latitude 52°15’, Longitude 122°7’) in the Cariboo Forest Region. The area
studied occupied about 65 ha, was located at an elevation of approximately 970 m, on
relatively flat terrain (S 8% slope) and included the B.C. Forest Service forest types
PL631 and F841. The stands are in the IDFdk3 biogeoclimatic subzone (Ray Coupé,
pers. comm.) and growing on a medium quality site (Ordell Steen, pers. comm.). The
site potential is rated as relatively good for the Cariboo Forest Region. The forest cover
consisted of a two-storied mixture of Douglas-fir and lodgepole pine with a minor
component of white spruce, Picea glauca (Moench) Voss. An outbreak of the mountain
pine beetle started in the Bull Mtn. area in 1971 and lasted until 1975 when the epidemic
completely collapsed (Doidge 1974, 1975). At the end of the infestation, many but not all
lodgepole pines had been killed. By 1985 the average age of the Douglas-fir component
was 63 years; surviving lodgepole pine averaged 107 years. The understory, defined as
trees which are less in height than the average lowest live branches of the overstory
(approximately 7 m), was well stocked and primarily Douglas-fir.
6.00 6.00
= 4.80 (a) Douglas-fir 4.80 (b) Lodgepole pine
5 3.60 3.60
= 2.40 2.40
z
x 1.20
1.20
0.00 0.00
1870 1885 1900 1915 1930 1945 1960 1975 1870 1885 1900 1915 1930 1945 1960 1975
140
(c) Douglas-fir 112 (@) Lodgepole pine
RADIUS (mm)
0.00 0.00
1870 1885 1900 1915 1930 1945 1960 1975 1870 1885 1900 1915 1930 1945 1960 1975
Fig. 1. Radial increment (a,b) and cumulative radial growth curve (c,d) from one surviving
Douglas-fir and one lodgepole pine tree from the Bull Mountain area of British Columbia, showing
the growth increase that occurred after the mountain pine beetle selectively killed a large
proportion of the lodgepole pine starting in 1971. The dotted line corresponds to a projection of the
growth trend (by linear regression) of the 20 years before 1971. The solid arrow points to the year
1971, the year in which the outbreak began. The open arrow indicates the start of an earlier release
period, around 1930, possibly caused by a previous mountain pine beetle epidemic.
18 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Two surveys of the area were conducted by the B.C. Min. of Forests and Lands,
Cariboo Region. The first, in 1975, consisted of 98 pairs of concentric circular plots on a
50 x 50 m grid. One of the plots in the pair was 0.008 ha in area and was intended to
measure overstory conditions; the second was 0.002 ha in size and was used to collect
data on the regeneration (File Report by R. Gasson, August 1976, on file at the Cariboo
Regional Office). The second survey was conducted in the fall of 1985, and consisted of
49 pairs of concentric circular plots ona 100 x 100 m grid. In this case, the plot sizes at
each point were 0.01 ha and 0.005 ha for the overstory and understory plots, respectively.
The objective of both surveys was to establish the amount and condition (alive or dead)
of the overstory and understory. For every overstory tree, diameter at breast height
(DBH) was measured. Growth rates after the beetle outbreak were determined in 1985
through collection of one breast-height increment core in each overstory plot from a live
dominant or co-dominant Douglas-fir (i.e., a total of 49 Douglas-fir cores collected).
Cores were also collected from 20 living dominant and co-dominant lodgepole pine
randomly selected throughout the stand.
Thinning response was measured by comparing the actual diameter of the cored trees
as of 1985 with a theoretical diameter the trees would have reached by this date in the
absence of the beetle outbreak. The theoretical diameter was calculated as follows.
Annual ring increments were measured on the cores to the nearest 0.01 mm using a
DIGIMIC tree ring measuring device (Holmann Electronics, Fredericton, N.B., Canada)
and the software developed by Alfaro et al. (1984). Every ring increment series was
plotted versus date of ring formation and crossdated (Stokes and Smiley 1968). A linear
regression curve was then fitted to the ring increments grown in the 20 years preceding
the initiation of the outbreak in 1971 (Fig. 1). By projection of this linear regression,
theoretical increments without thinning were calculated for every year between 1972 and
1985. In a few cases where the linear regression method gave poor projections (e.g.,
projected increments dipped below the X-axis), the projection was discarded and
theoretical increments for the 1972-1985 period were assumed equal to the average
growth of the 5 years that preceded 1972. Theoretical radii and diameters were
determined by accumulation of the tree ring series but using the theoretical increments
for the 1972-1985 period. The actual and theoretical diameters are respectively referred
to hereafter as the thinned and unthinned tree diameter.
For both Douglas-fir and lodgepole pine, mean diameter and basal area gain per tree
due to thinning was calculated as the difference between the thinned and unthinned tree
diameter. In addition, a study was done of the relationship between diameter and basal
area gain per tree versus tree diameter and age at the start of the infestation (1971). The
percentage annual growth of thinned and unthinned trees for the period between 1971 and
1985 was calculated using the compound interest formula (Husch et al. 1972).
To confirm that any increase in growth rate during the post-outbreak years was due to
a thinning effect and not to a coincident period of abnormally favourable weather,
increment cores were randomly collected from a 20 additional lodgepole pine trees of
similar age and size to those on Bull Mtn., but from a stand which had not undergone a
beetle outbreak. The stand selected was located near Lyne Creek, about 10 km northwest
of the Bull Mtn. study site, and was approximately 100 years old in 1985 (age range 83-—
112). It was located in the same biogeoclimatic subzone, had similar stocking levels, and
was also growing on a medium site (Steen, pers. comm.). Annual ring widths in these
cores were measured and graphed versus dates, with the same instruments and methods
used for the Bull Mtn. cores.
RESULTS AND DISCUSSION
Although no direct data are available on the stand structure before the beetle epidemics at
this location, an approximation was obtained by adding the figures for the number of
beetle-killed and live trees reported in 1975. Before the beetle outbreak, the overstory
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 19
contained approximately 560 living stems/ha, consisting of 80% lodgepole pine, 19%
Douglas-fir and 1% white spruce. In 1985, 14 years after the start of the beetle epidemic,
the stand contained 430 living stems/ha, with the pine component reduced to 20% and
the Douglas-fir and white spruce increased to 77% and 3%, respectively. These changes
in stand structure were due to the high mortality of the pine induced by the beetle and to
the acceleration of Douglas-fir growth which resulted in understory trees being recruited
into the overstory. Seventy-six percent of the pine stems/ha were dead (81% by basal
area) which represented 38% of the total stems/ha in the stand (43% by basal area).
In 1975, the understory contained an average 3190 trees/ha composed of 90%
Douglas-fir and 5% each of lodgepole pine and white spruce. In 1985, the understory
contained 2698 trees/ha with a similar composition; 91% Douglas-fir, 7% lodgepole pine
and 2% white spruce.
Thinning response of Douglas-fir
All but one of the 49 Douglas-fir trees cored showed a marked increase in radial growth
in the period that followed the beetle outbreak, relative to the trend line fitted to the
growth prior to the start of the infestation in 1971 (Fig. 1). The increase began | to 4 years
from the start of the infestation, and reached a maximum 5 to 7 years after. By 1985,
many trees still had growth rates above the trend line. However, considerable tree-to-tree
variation occurred which was probably due to spatial and temporal differences in pine
mortality, to a relatively heterogeneous stand structure and to variations in the sample
trees’ crown size and position in the crown canopy.
Average DBHib (DBH inside bark) of Douglas-fir in 1985 was 13.4 cm (range 8.3-
24.6). The 1985 DBHib in the absence of the thinning effect, was estimated at 12.0 cm
(7.2—23.6). Hence, the average diameter gain due to the beetle-induced thinning was 1.4
cm (O-4.4), which amounted to an average increase of 11.7% (0-57%) over the size of
the unthinned tree (average increase of 21% by basal area).
Regression analysis indicated that the thinning response (as measured by the differ-
ence in DBH with and without thinning) was lower in the large diameter and older trees
than in small diameter and younger trees (F = 6.0 and F = 5.9, for the diameter and age
relationships, respectively; both significant at P < 0.05). However, there was consider-
able variation in the response, particularly among trees of small diameter or of young
age. The regression line explained only about 10% of the variance. Inclusion of the
number or percentage of lodgepole pine trees killed in each plot in the analysis did not
improve the regression.
ANNUAL GROWTH RATE (%) DIFFERENCE
460" 6 10> 12°°14° 16° 187" 20 © 22 20 40 60 80 100 = 120 8140
DBH IN 1971 AGE IN 1971
Fig. 2. Difference between thinned and unthinned annual growth rates (%) of Douglas-fir versus
initial DBH (cm) and tree age (years) in 1971. Thinning was the result of a mountain pine beetle
outbreak, which killed a large proportion of the lodgepole pine.
20 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Based on the 1971 and 1985 diameters, and using the compound interest formula,
thinned and unthinned annual growth rates averaged 2.9% (0.2-6.5%) and 2% (0.1-—
5.7%) per year, respectively. In terms of basal area, the average annual growth rate was
6% (0.3-13.5%) per year with thinning, and 4% (0.2—11.7%) per year without thinning.
The difference between thinned and unthinned annual growth rates is shown in Fig. 2.
Again, these figures show larger percentage growth gains among the small diameter
trees of young age relative to larger or older trees. Trees with diameters greater than 21
cm or older than 140 years showed no response. For the same age or diameter, there was a
large tree to tree variation in the thinning response (Fig. 2).
Thinning response of surviving lodgepole pine
Fourteen out of the 19 lodgepole pine sampled showed a similar growth acceleration
period after the start of the beetle outbreak of 1971 to that in Douglas-fir. The increase
started 2-6 years from the start of the outbreak and peaked 5-9 years after; growth still
remained above the trend line as of 1985.
Average 1985 DBHib for lodgepole pine was 19.5 cm (range 12.6—26.5 cm). The 1985
mean unthinned diameter was estimated at 18.5 cm (12.7—25.0 cm). Hence, the average
diameter gain due to thinning (including the trees that did not show a response), over the
14 year post-outbreak period was 1.0 cm which was equivalent to a 5.4% increase over
the size of the unthinned tree (12.3% by basal area). In lodgepole pine the degree of
response to thinning was not significantly related (P > 0.05) to the diameter or age of the
trees at the start of the infestation.
The percentage annual diameter growth rates for the 14 year period ending in 1985,
doubled from 0.4% per year (0.1-0.7%) without thinning to 0.8% per year (0.1-1.7%)
with thinning. Annual basal area growth rates averaged 1.7 and 0.8% per year with and
without thinning, respectively.
Examination of the plots of annual ring increment for lodgepole pine at Bull Mtn.
indicated an earlier release period starting about 1930 (Fig. 1), probably caused by an
earlier beetle infestation. The Douglas-fir in the stand was younger than the lodgepole
pine and originated about that date, possibly by seeding into the openings created by the
bark beetle.
Growth in the Lyne Creek area
Increment cores of lodgepole pine from Lyne Creek did not show the increase in diameter
growth after 1971 seen at Bull Mtn. On the contrary, tree rings from this area showed the
normal pattern of decline with age and growth in the 1972-1985 period was, on average,
17% less than growth in the previous 10 years. Since the two locations are exposed to
similar climatic conditions, it was concluded that the release at Bull Mtn. was due to the
beetle-induced thinning.
DISCUSSION
The mountain pine beetle caused a drastic change in the stand structure in this area as the
overstory changed from largely lodgepole pine, a shade intolerant species, to predomi-
nantly Douglas-fir, a more tolerant species. Removal of the mature pine, a seral species
on this site, increased the rate of successional change towards a Douglas-fir dominated
stand. The same pattern of change does not occur in much of the Chilcotin where
lodgepole pine is a pyraledaphic climax species and no shade-tolerant conifer species are
available to replace beetle-killed pine. Stands in the IDFdk3 biogeoclimatic subzone
with significant Douglas-fir or white spruce components can withstand heavy pine
mortality levels and still become commercially viable in a reasonable period. Overstory
Douglas-fir stocking densities on Bull Mtn. increased from 106 stems/ha (19% of the
stand) in 1975 to 331 stems/ha (77% of the stand) in 1985 with an average inside bark
diameter of 13.4 cm. The diameter growth response of the Douglas-fir and residual
lodgepole pine will help produce a commercially viable stand on the site within 15-20
years (assuming an economic threshold mean outside bark DBH of 25—30 cm). The shift
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 21
to a higher value species like Douglas-fir will have an additional economic impact on the
stand.
Several bark beetle researchers have indicated that vigorous growth increases tree
resistance to bark beetle attack and shortens outbreak duration (Brown et al. 1987, Cole
and Amman 1969, Nebeker and Hodges 1983, Vité and Wood 1961, Waring and Pitman
1985). Before the bark beetle outbreak, lodgepole pine growth rates were near stagnation
and the large proportion of the lodgepole pine that showed release response in this study
could have been a factor in the termination of the outbreak in the area, along with a
depletion of the most attractive host.
REFERENCES
Alfaro, R.I., E. Wegwitz, A.D. Erickson and W.J. Pannekoek. 1984. A micro-computer based data reader and
editor for the DIGIMIC Tree Ring Measuring System. Envir. Can., Can. For. Serv. Res. Notes 4:30-31.
Amman, G.D., M.D. McGregor, PB. Cahill and W.H. Klein. 1977. Guidelines for reducing losses to the
mountain pine beetle in unmanaged stands in the Rocky Mountains. USDA For. Ser. Gen. Tech. Rep.
INT-36. 19 pp.
Brown, M.W., T.E. Nebeker and C.R. Honea. 1987. Thinning increases loblolly pine vigor and resistance to
bark beetles. SJAF 11:28-31.
Cole, W.E. and G.D. Amman. 1969. Mountain pine beetle infestations in relation to lodgepole pine diameters.
USDA For. Serv. Res. Note INT-95. 7 pp.
Cole, W.E. and G.D. Amman. 1980. Mountain pine beetle dynamics in lodgepole pine forests. Part I: course of
an infestation. USDA For. Serv. Gen. Tech. Rep. INT-89. 56 pp.
Coupe, R. Assistant Ecologist, B.C. Ministry of Forests, Williams Lake, B.C.
Craighead, EC. 1925. The Dendroctonus problem. J. For. 23:340-354.
Doidge, D. Regional Pathology Specialist, B.C. Ministry of Forests, Williams Lake, B.C.
Doidge, D. 1974. Forest insect and disease conditions. Cariboo District 1974. Envir. Can., Can. For. Serv.,
Pacific For. Res. Centre Inf. Rep. BC-X-116. 21 pp.
Doidge, D. 1975. Forest insect and disease conditions. Cariboo Forest District, British Columbia, 1975. Envir.
Can., Can. For. Serv., Pacific For. Res. Centre, Inf. Rep. BC-X-137. 9 pp.
Johnstone, W.D. 1982. Heavy thinning accelerates growth of 77-year-old lodgepole pine. Envir. Can., Can. For.
Serv., Northern For. Res. Centre, Forest Management Note No. 16. 3 pp.
Husch, B., C.I. Miller and T.W. Beers. 1972. Forest mensuration. The Ronald Press Co. 410 pp.
Knutson, D. and R. Tinning. 1986. Effects of dwarf mistletoe on the response of young Douglas-fir to thinning.
Can. J. For. Res. 16:30-35.
Nebeker, T.E. and J. Hodges. 1983. Influences of forestry practices on host susceptibility to bark beetles. Z.
Ang. Ent. 96:194-208.
Safranyik, L., D.M. Shrimpton and H.S. Whitney. 1974. Management of lodgepole pine to reduce losses from
the mountain pine beetle. Envir. Can., Can. For. Serv., Pacific Forest Research Centre, Info. Report. 235 pp.
Smith, M.S. 1962. The practice of silviculture. John Wiley & Sons, Inc. New York. 578 pp.
Steen, O. Regional Ecologist, B.C. Ministry of Forests, Williams Lake, B.C.
Stokes, M.A. and T.L. Smiley. 1968. An introduction to tree ring dating. The U. of Chicago Press. 73 pp.
Vité, J.P. and D.L. Wood. 1961. A study on the applicability of the measurement of oleoresin exudation
pressure in determining susceptibility of second growth Ponderosa pine to bark beetle infestation. Contr.
Boyce Thomson Inst. 21:67-78.
Waring, R.M. and G.B. Pitman. 1985. Modifying lodgepole pine stands to change susceptibility to mountain
pine beetle attack. Ecology 66:889-897.
22 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Role of needles in close-range host selection by the white pine
weevil on Sitka spruce :
L.J. HARRIS!, R.I. ALFARO!, and J.H. BORDEN
CENTRE FOR PEST MANAGEMENT
DEPARTMENT OF BIOLOGICAL SCIENCES
SIMON FRASER UNIVERSITY
BURNABY, B.C. V5SA 1S6
1. Present address of L.J. Harris is Plant Research Centre, Central Experimental Farm, Agriculture
Canada, Ottawa K1A 0C6 and of R.I. Alfaro is Pacific Forestry Centre, 506 West Burnside Rd.,
Victoria, B.C. V8Z 1MS5. Please direct reprint requests to J.H. Borden.
ABSTRACT
The white pine weevil, Pissodes strobi Peck, is apparently induced to feed and oviposit
on the cortex of leaders of Sitka spruce, Picea sitchensis (Bong.) Carr, in part through the
influence of needles. In laboratory feeding bioassays, mature needles were shown to
contain non-volatile feeding deterrents, which probably direct weevils away from them to
feed on the bark. In addition, weevils fed more frequently on agar bark discs with spruce
needles or toothpicks inserted in them than on control discs, suggesting that the needles
have a positive thigmatactic effect on close range host selection.
INTRODUCTION
Stands of Sitka spruce, Picea sitchensis (Bong.) Carr (Silver 1968), Englemann spruce,
Picea engelmanni Parry (Stevenson 1967), and eastern white pine, Pinus strobus L.
(Belyea and Sullivan 1956) are seriously plagued by attacks of the white pine weevil,
Pissodes strobi Peck. In the spring, the weevils apparently orient visually to the terminal
leader of the tree (VanderSar and Borden 1977a). They are induced to feed on the bark by
chemical stimulants (VanderSar and Borden 1977b; Alfaro et al. 1980), and feed and
Oviposit in the one-year-old leader directly below the apical bud cluster (Silver 1968).
Although the needles contain some cuticular feeding stimulants (Alfaro et al. 1980), no
feeding has been observed on them. However, leaders with sparse needle growth are less
often attacked than those with high needle density (unpublished observation). The
weevils find the terminal bud through positive phototaxis and negative geotaxis
(VanderSar and Borden 1977c), but the precise mechanisms by which the weevils orient
to the bark on one-year-old branches for feeding and on leaders for feeding and
Oviposition, while avoiding other sites, are unknown. Our objective was to investigate
the role of Sitka spruce needles in regulating feeding activity by P. strobi.
MATERIALS AND METHODS
Terminal leaders of Sitka spruce containing mature P. strobi larvae were collected from
Nootka Island and Vancouver Island and stored, until required, in a cold room at 2°C for
up to 4 months. Weevils emerged at room temperature in cages, and were maintained at
4°C on a modified diet (Zerillo and Odell 1973). Some adult weevils were also collected
in the spring from plantations in the University of British Columbia Forest, Maple Ridge,
B.C. All Sitka spruce samples were collected from sapling trees at the U.B.C. Research
Forest or Harrison Hot Springs in the lower mainland of British Columbia. They were
stored at 5°C until used.
Laboratory experiments employed the feeding bioassay developed by Alfaro et al.
(1979). Single or paired agar discs containing the candidate stimuli were covered with
lens paper, and set in paraffin wax in petri dishes. The number of feeding punctures made
by weevils in the lens paper indicated the amount of feeding activity in response to the
stimulus incorporated in the agar. Each replicate (dish), containing three weevils, was
placed on a counter-top at room temperature and constant light. As weevils of either sex
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 23
feed similarly (VanderSar and Borden 1977b), no distinction was made as to the sex of the
weevils used.
To test for possible feeding deterrents in the needles, single agar disc treatments were
prepared. A control treatment contained 1% dried and ground Sitka spruce bark while
experimental treatments contained, in addition to 1% bark, dried and ground Sitka
spruce needles from the leader. These were incorporated at concentrations of 0.1, 1.0,
2.5 and 10% into the agar. Each treatment was tested for 8 h and had 15 replicates.
The physical effect of needles on feeding activity was assessed by two paired
experiments with all agar discs containing 1% dried bark. Mature needles were cut from
lateral branches and their cut ends were sealed by dipping in paraffin wax. In the first
experiment, one agar disc had three needles inserted into the agar perpendicular to the
surface, while the other disc had no needles. The second experiment had one disc with
three inserted needles and one with three inserted toothpicks, cut to needle length.
Initially there were 20 replicates in each 40 h experiment, but replicates in which weevils
did not feed at all (four in the first, and one in the second experiment) were deleted.
Paired means in each experiment were compared by t tests, a = 0.05.
RESULTS AND DISCUSSION
When the weevils were given a choice between Sitka spruce bark agar discs and those
with needle powder added, there was a prounounced deterrent effect of the needles,
especially at higher concentrations (Fig. 1). Thus non-volatile feeding deterrents in the
needles appear to override the effect of weak, cuticular feeding stimulants (Alfaro et al.
MEAN NUMBER OF FEEDING
PUNCTURES (+ SE)
0 2 4 6 8 10
CONCENTRATION OF NEEDLE
POWDER (%) IN BARK-AGAR DISCS
Fig. 1. Feeding response of P. strobi to Sitka spruce bark agar disks containing increasing
amounts of Sitka spruce needle powder. Curve fitted by hand.
24 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
EXPERIMENT 1 EXPERIMENT 2
G)
O
29
AY)
15
10
Oo
MEAN NUMBER OF FEEDING PUNCTURES (+ S.E.)
BARK-AGAR BARK-AGAR BARK-AGAR BARK-AGAR
DISC DISC WITH DISC WITH DISC WITH 3
3 NEEDLES 3 NEEDLES TOOTHPICKS
INSERTED INSERTED INSERTED
Fig. 2. Feeding response of P. strobi to Sitka spruce bark agar discs in the presence of spruce
needles or toothpicks. Bars topped by the same letter are not significantly different, t test, |
P = 0:05;
1980), and may in part direct the weevils away from the needles towards the appropriate
site for feeding and oviposition, i.e. the bark surface. .
Vertically implanted needles in Sitka spruce bark agar discs significantly increased
feeding by weevils (Fig. 2). The weevils did not discriminate between Sitka spruce
needles and plain toothpicks inserted into the agar. They were observed to feed
preferentially while touching the needles or toothpicks, suggesting that there is a thig-
motactic response.
A thigmotactic requirement also occurs in the smaller European elm bark beetle,
Scolytus multistriatus (Marsham), which feeds in the crotch of elm twigs (Peacock et al.
1967). The hypothesis for a thigmotaxis is supported by our field observations that the
majority of feeding weevils are found in direct contact with needles. This behavior may
be of adaptive advantage to the weevils, as the needles may provide concealment or
physical protection from predators such as birds.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 25
REFERENCES CITED
Alfaro, R.I., H.D. Pierce, Jr., J.H. Borden, and A.C. Oehlschlager. 1979. A quantitative feeding bioassay for
Pissodes strobi Peck (Coleoptera: Curculionidae). J. Chem. Ecol. 5:663-671.
. 1980. Role of volatile and non-volatile components of Sitka Spruce bark as feeling stimulants for
Pissodes strobi (Peck) (Coleoptera: Curculionidae). Can. J. Zool. 58:626-632.
Belyea, R.M. and C.R. Sullivan. 1956. The white pine weevil: a review of current knowledge. For Chron.
32:56-67.
Peacock, J.W., B.H. Kennedy and EW. Fisk. 1967. A bioassay technique for elm bark beetle feeding
stimulants. Ann. Entomol. Soc. Am. 60:480-481.
Silver, G.T. 1968. Studies on the Sitka spruce weevil, Pissodes sitchensis, in British Columbia. Can. Entomol.
100:93-110.
Stevenson, R.E. 1967. Notes on the biology of the Engelmann spruce weevil, Pissodes engelmanni,
(Coleoptera: Curculionidae) and its parasites and predators. Can. Entomol. 99:201-203.
VanderSar, T.J.D. and J.H. Borden. 1977a. Visual orientation of Pissodes strobi Peck (Coleoptera: Cur-
culionidae) in relation to host selection behavior. Can. J. Zool. 55:2042—2049.
. 1977b. Aspects of host selection behavior of Pissodes strobi Peck (Coleoptera: Curculionidae) as
revealed in laboratory feeding bioassays. Can. J. Zool. 55:405-414.
. 1977c. Role of geotaxis and phototaxis in the feeding and oviposition behavior of overwintered
Pissodes strobi. Environ. Entomol. 6:743-749.
Zerillo, R.T. and T.M. Odell, 1973. White pine weevil (Pissodes strobi Peck): arearing procedure and artificial
medium. J. Econ. Entomol. 66:593-594.
Efficacy of deltamethrin and Bacillus thuringiensis Berliner ssp
kurstaki on larvae of winter moth, Operophtera brumata (L.)
(Lepidoptera: Geometridae) attacking blueberry in the
Lower Mainland of British Columbia
D. H. SHEPPARD!, J.H. MYERS!, S. FITZPATRICK2, and H. GERBER?
1. DEPTS. OF ZOOLOGY AND PLANT SCIENCE
UNIVERSITY OF BRITISH COLUMBIA, VANCOUVER, B.C. V6T 2A$
2. RESEARCH STATION, AGRICULTURE CANADA
N.W. MARINE DRIVE, VANCOUVER, B.C.
3. B.C. MINISTRY OF AGRICULTURE AND FISHERIES, CLOVERDALE, B.C.
ABSTRACT
Two pesticides were evaluated for control of the European winter moth, Operophtera
brumata (L.), in blueberries in Richmond, British Columbia. The pyrethroid, del-
tamethrin (Decis), was effective against this pest. The Bacillus thuringiensis product
Dipel (WP) was ineffective. Deltamethrin provides an alternative to the currently used
organo-phosphate pesticides.
INTRODUCTION
The European winter moth, Operophtera brumata (L), was first introduced to the east
coast of North America (Nova Scotia) as early as the 1930s (Cuming 1961, Embree 1965,
1970), and to southern Vancouver Island (Victoria, British Columbia) prior to 1970
(Gillespie et al. 1978, Roland 1988). Since then, the winter moth has spread to the
mainland of British Columbia and is most prevalent in the southwestern communities of
Ladner, Tsawwassen and Richmond.
26 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
CONTROL
DIPEL
C_] Before
Ma After
DECIS
CC] Before
Mm After
Mean No. Larvae/ Bud Mean No. Larvae/ Bud Mean No. Larvae/ Bud
Fig. 1. Mean number of winter moth larvae/bud in 3 replicates of control, deltamethrin (Decis),
and Bacillus thuringiensis plots before (April 11, 1990) and after treatment (April 18, 1990).
* indicates plots that significantly declined in density over this period in t-test comparisons. S.E.
bars given.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 OF
Winter moth eggs hatch in early April and larvae immediately begin to feed on new
buds. In Richmond, O. brumata have reached high densities in Betula (birch) woodland,
causing near total defoliation in some areas. Since 1988 winter moth larvae have severely
damaged unsprayed commercial blueberries, Vaccinium ovatum L. Blueberry growers
have had varied success combating this new pest with organo-phosphorus compounds
such as malathion, carbaryl and azinphos-methyl. The time, method and number of
applications of these compounds probably determined the success rate. This study
evaluates the effectiveness of two insecticides with low toxicity to terrestrial
vertebrates —the microbial pesticide Bacillus thuringiensis Berliner ssp kurstaki (Dipel
WP), and the synthetic pyrethroid deltamethrin (Decis 2.5 EC)—for control of winter
moth on commercial blueberry bushes.
MATERIALS AND METHODS
Studies were conducted in a !/4 ha blueberry field in Richmond, south of Vancouver. The
plants, mostly of the variety Blue Crop, had not been pruned or commercially harvested
for several years. Nine plots, each containing three rows of three bushes, were allotted
randomly to the two treatments (B. thuringiensis and deltamethrin) and the untreated
control. From previous observations we knew that winter moth were not evenly
distributed in the field so we attempted to locate plots so that each treatment was
represented in different parts of the field. However, the treatments were not completely
blocked. Each plot was bordered by two rows of unsprayed bushes to prevent spray drift,
and pruned so that sprayed bushes did not contact unsprayed bushes.
From mid-March blueberry buds were searched every 3 or 4 days for hatched larvae.
Larvae were first observed on 4 April, 1990. Pre-treatment larval counts were made on
April 10, 1990, six days after the first larvae were found at the site. Counts were made by
arbitrarily selecting 24 fruit buds from each bush, six from each side of the bush in the
ordinal positions (216 per plot). Of the 24 buds selected from each bush, 15 were
randomly chosen and a dissecting microscope used to count the number of larvae per
bud. For the post-treatment counts on April 18 and May 1 only 16 buds per bush were
selected. Sprays were applied using a hand-pumped backpack sprayer on April 11.
Bushes were sprayed lightly, each receiving approximately '/2 1 of spray material. Dipel
was applied at 1100 grams of active ingredient per hectare (approximately 0.5 g per
bush). Decis was applied at 100 ml (2.5 g active ingredient) per hectare (approximately
0.13 ml or 32.5 mg active ingredient per bush).
The effect of B. thuringiensis was tested in a laboratory study. Twenty field collected
larvae were placed in individual thin plastic cups and fed blueberry leaves dipped in the
B. thuringiensis product Dipel. Cups containing larvae were placed in an open air
insectary and fed fresh leaves after four days. New untreated leaves were provided every
two days following the treatment. Death rates were compared to twenty control
individuals fed fresh untreated leaves. This experiment was carried out twice, once
beginning on April 23, 1990 and again beginning on May 14, 1990.
RESULTS AND DISCUSSION
The mean number of larvae/bud varied greatly among plots (Figure 1). By chance two of
the three control and B. thuringiensis plots had approximately twice the density of winter
moths prior to treatment than did the plots to be treated with Decis. Unfortunately,
because we did not identify the bushes so as to identify pre- and post-treatment samples
from the same bushes we were not able to carry out an analysis of covariance. We have
therefore compared changes in density for each plot in each treatment using a t-test as
indicated on Figure | and tested for overall change in larval density before and after
treatment by using the three replicates for each treatment in a t-test (Table 1).
Overall, B. thuringiensis (Dipel WP) did not significantly reduce numbers of winter
moth larvae (Table 1) although numbers of larvae were significantly lower on 18 April in
two of the plots (Figure 1). Since larvae in the flower buds have a major impact on
28 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Table 1
The effect of two insecticides against Operophtera brumata in blueberries.
Richmond, B.C. 1990. N = 3 for all means.
Mean Number of Larvae/Bud (S.E.)
April 10 April 18 May 1
Bacillus thuringiensis (Dipel WP) 1.00 (0.50) 0.67 (0.35) 0.83 (0.46)
Deltamethrin (Decis 2.5 Ec) 0.46 (0.01) 0.01 (0.01)* 0.00 (0.00)*
Control 1.07 (0.59) 1.0 (0.37) 0.67 (0.15)
* t= 36, P<0.01 for both comparison of density after treatment to before.
blueberry production, for sufficient control, almost complete mortality is necessary.
Bacillus thuringiensis did not provide this. Tonks et al. 1978, observed significantly
lower densities of winter moth larvae as compared to controls in apple leaf buds following
applications of Dipel W.P. and Thuricide HPC, but they do not report the date or how long
after egg hatch these sprays were applied. In similar tests on filberts (Corylus avellanae
L.) in Oregon, B. thuringiensis (Thuricide HPC) was also ineffective in the control of
winter moth damage (AliNiazee 1986). Bacillus thuringiensis (Dipel) also did not
control Bruce’s spanworm (Operophtera bruceata {Hulst]) on the blueberry variety
Rancocas (Raine and Clements 1984).
In our laboratory study, B. thuringiensis had no effect on the winter moth larvae fed
on April 23 when compared with the controls, but survival was poor in both groups.
However, in the second test, fourth and fifth instar larvae fed blueberry leaves soaked in
Dipel died much more rapidly than the controls. In the first week 30% of the larvae fed
with B. thuringiensis had died compared to only 5% of the controls (Chi-squared =
4.33, P <0.05). By the end of the second week, 80% of the test larvae died compared to
40% of the controls (Chi-squared = 6.7, P < 0.05). By May 30, 10 control larvae had
pupated while only 3 B. thuringiensis fed larvae pupated.
Deltamethrin provided complete control in this study. In the first count after treatment
(April 18), only one larva was found alive (Figure 1) and the reduction in the density of
winter moth larvae was significant (t = 36, P< 0.01 N = 3) (Table 1). If any larvae
hatched after spraying, they did not survive and no winter moth larvae successfully
invaded the bushes from the surrounding unsprayed plants. No live larvae were counted
on May | on these plots. Tonks et al. 1978 found similar good control of winter moth with
another synthetic pyrethroid, permethrin, on apples, and another synthetic pyrethroid,
fenvalerate, significantly reduced winter moth on filberts (AliNiazee 1986). Raine and
Clements (1984) found that deltamethrin significantly reduced the number of Bruce’s
spanworm in blueberry. Sanford (1985) obtained good control of winter moth on the
McIntosh variety of apples with deltamethrin.
Growers in Richmond who have successfully controlled the winter moth during the
last few years have applied organo-phosphate sprays several times between initial and
final egg hatch in early to mid-April. The timing of different chemical sprays has been
shown to be important in the control of winter moth on filberts (AliNiazee 1986).
AliNiazee recommended that sprays should be applied at 90-95 percent hatch to prevent
damage from larvae that hatch after spraying. This, of course, risks damage to the crop
from the initial outbreak. Multiple applications of organo-phosphates can prevent early
and late damage (personal communication from growers).
However, a single spray of deltamethrin (Decis) was sufficient in our tests to provide
complete control, and the synthetic pyrethroid fenvalerate, was equally successful on
filberts (AliNiazee 1986). Although no data are available from our study to show
percentage hatch at the time of spray, Embree (1970) found mid-hatch to occur
approximately seven days after initial hatch. We sprayed seven days after the first larvae
were observed.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 29
The advantage of using the synthetic pyrethroids is that they are less toxic to
mammals (lethal oral dose for a rat is 135 mg/kg for Decis and 4.4 mg/kg for Guthion, a
spray commonly used by blueberry growers [Thompson 1989]). Dead vertebrates (ring-
necked pheasants, eastern cottontail rabbits and numerous small mammals) have been
found in the blueberry fields suggesting that a side effect of the potency of some of the
organo-phosphate pesticides used (Sheppard, personal observation). However, of con-
cern is the toxicity of pyrethroids to fish and the dangers of contamination of water from
the marshy habitat in which blueberries are grown. Also, while pyrethroids currently
successfully control winter moth larvae, the high mortality will undoubtedly rapidly
select for resistant strains of moths. Because winter moth eggs hatch early in April and
only a single application is necessary, deltamethrin can be used before pollinators are
active in the blueberry fields. Therefore, deltamethrin should have little impact on this
important component of the system.
Our laboratory study of B. thuringiensis also suggests that winter moth larvae are
more susceptible to this pesticide at later instars. This may be related to the greater
consumption of leaf material and therefore more B. thuringiensis by the larger caterpil-
lars. Although B. thuringiensis has little potential as a control agent in blueberries, it
may be a safe and sufficiently effective agent to be used in urban areas to reduce damage
from later instars of winter moth larvae on non-crop plants. This potential application
needs further study.
ACKNOWLEDGEMENTS
This research was supported by a grant from NSERC, Agriculture Canada and the
Blueberry Development Council of B.C. Mention of commercial products in this paper
does not constitute endorsement or recommendation for use. We thank Rosi van Meel and
Jackie McPhee for help with this work.
REFERENCES
AliNiazee, M.T. 1986. The European winter moth as a pest of filberts: damage and chemical control. J.
Entomol. Soc. Brit. Columbia. 83:6-12.
Cuming, EG. 1961. The distribution, life history, and economic importance of the winter moth, Operophtera
brumata (Lepidoptera: Geometridae) in Nova Scotia. Can. Entomol. 93:135-142.
Embree, D.C. 1965. The population dynamics of the winter moth in Nova Scotia, 1954-1962. Mem. Entomol.
Soc. Can. No. 46, 57 pp.
Embree, D.C. 1970. The diurnal and seasonal patterns of hatching of winter moth eggs, Operophtera brumata
(Lepidoptera: Geometridae). Can. Entomol. 102:750-768.
Gillespie, D.R., T. Finlayson, N.V. Tonks, and D.A. Ross. 1978. Occurrence of the winter moth, Operophtera
brumata (Lepidoptera: Geometridae) on southern Vancouver Island, B.C. Can. Entomol. 110:223-224.
Raine, J. and S.J. Clements. 1984. Insecticide trials for control of leafrollers. Agriculture Canada Pesticide
Research Report. p. 61.
Roland, J. 1988. Decline in winter moth populations in North America: Direct versus indirect effect of
introduced parasites. J. Anim. Ecol. 57:523-531.
Sanford, K.H. 1985. Control treatments and their effect on a later hatching mirid. Agriculture Canada
Pesticide Research Report. p. 30.
Thompson, W.T. 1989. Agricultural Chemicals. Book I. Fresno, CA. 288 pp.
Tonks, N.V., PR. Everson, and T.L. Theaker. 1978. Efficacy of insecticides against geometrid larvae,
Operophtera spp. on southern Vancouver Island, British Columbia. J. Entomol. Soc. Brit. Columbia 75:6—-
12.
30 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Recommendations for sampling and extracting the eggs of the
western hemlock looper, Lambdina fiscellaria lugubrosa,
(Lepidoptera: Geometridae)
T.L. SHORE
FORESTRY CANADA, PACIFIC FORESTRY CENTRE
506 W. BURNSIDE RD., VICTORIA, B.C. V8Z 1M5
ABSTRACT
No significant differences were found in the numbers of both new and old western
hemlock looper eggs per 100 grams of lichen between three crown levels. Representative
samples may be collected from lower crown levels with pole pruners, rather than from
upper crown levels, which usually involves tree felling.
Hot water is more efficient than 2% chlorine bleach for extracting the eggs from the
lichen on which they are laid. However, the bleach method is non-destructive and allows
the eggs to be reared in order to assess parasitism and fertility. These characteristics can
also be identified through egg color using the hot water method, but the parasitoid species
cannot be identified. It is recommended that the hot water method be used for forecasting
population trends and the bleach method for specific information about parasitoids.
RESUME
Aucune différence notable n’a été trouvée entre le nombre d’oeufs d’arpenteuses
présents, par 100 grammes de lichen, sur les spécimens jeunes et sur les spécimens agés
de pruches de 1’Ouest, les échantillons ayant été prélevés a trois niveaux de la cime. Pour
éviter l’abattage, 1’échantillonnage se fait non pas au faite mais au bas de la cime, au
moyen d’un échenilloir-élagueur.
Pour extraire les oeufs de leur support de lichen, l’eau chaude donne de meilleurs
résultats que |’emploi d’une solution chlorée a 2%. Mais la méthode de la solution chlorée
est non destructive et permet de maintenir en vie les oeufs pour en dégager les
caractéristiques parasitologiques et la fertilité. Précisons toutefois que si la méthode de
l’eau chaude permet de caractériser les parasitoides par 1’ observation de la coloration des
oeufs, elle ne permet pas d’en identifier les espéces. On recommande donc la méthode de
l’eau chaude pour étudier les tendances générales des populations de parasitoides et celle
de la solution chlorée pour dégager des données spécifiques sur celles-ci.
INTRODUCTION
The western hemlock looper (WHL), Lambdina fiscellaria lugobrosa (Hulst) (Lepidop-
tera: Geometridae), is periodically a destructive defoliator of western hemlock, Tsuga
heterophylla (Raf.) Sarg., and to a lesser extent other associated coniferous tree species
(Harris et al. 1982). A reliable population index is requirea to predict an approaching
epidemic of western hemlock looper. Estimates of frass quantity (Thomson 1949), and
numbers of eggs (Kinghorn 1952; Thomson 1958; Carolin et al. 1964), larvae (Harris et
al. 1982) and pupae (Shore 1989), have all been examined as population indicators. The
egg is the preferred stage for sampling WHL because it is the overwintering stage, and is
relatively stable in numbers, position and time through the fall and winter months.
Most of the early research on the WHL was done in coastal forests (e.g., Hopping
1934; Richmond 1947; Wyatt 1946; Thomson 1949, 1957; Kinghorn 1954; Carolin et al.
1964), but since the 1950s most infestations in British Columbia have occurred in interior
forests (Harris et al. 1982). This change in outbreak location is probably due to a
reduction in area of mature western hemlock forest on the coast because of a longer
history of logging. On the coast it was found that the WHL laid most ot its eggs in moss
on tree trunks, limbs, logs and on the forest floor (Hopping 1934; Carolin et al. 1964).
However, in interior forests the preferred oviposition site is on lichens (Alectoria spp.)
which grow mainly on the beanches of trees (Thomson 1958). The Forest Insect and
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 3]
Disease Survey (FIDS) of Forestry Canada developed a sampling index based on the
number of WHL eggs per 100 grams dry weight of these lichens (Shore 1985, FIDS
General Instruction Manual, Forestry Canada, unpub. ). |
A study was conducted comparing the number of WHL eggs per 100 grams of lichen
between three crown levels of hemlock trees. If the number of eggs found in lichen from
the lower crown is the same, or can be related to the number of eggs in lichen in the mid-
and upper crown levels then sampling can be simplified; lichen can usually be collected
from the lower crown using pole pruners, whereas sampling from other crown levels
often necessitates felling the tree.
Removing insect eggs by hand from the substrate to which they have been attached is
extremely time consuming and inefficient (Carolin et al. 1964, Condrashoff 1967, Otvos
and Bryant 1972). Several methods have been presented for washing eggs from the
substrate including NaOH solution (Condrashoff 1967, Shepherd. and Gray 1972), hot
water (Eidt and Cameron 1970, Gray et al. 1973) and chlorine bleach solution (Otvos and
Bryant 1972). The hot water method was adapted by FIDS for removing western hemlock
looper eggs from the lichen (Shore 1985). However, the chlorine bleach method has the
advantage of being non-destructive to live eggs (Otvos and Bryant 1972), unlike the hot
water and NaOH methods, and therefore it can be used for biological studies to determine
viability and parasitism. An experiment was conducted in which the bleach method was
compared with the hot water method for WHL egg extraction from lichen samples.
METHODS AND MATERIALS
Comparison of number of eggs at three tree crown levels
To examine the effect of tree crown level on the number of eggs per 100 g lichen, recently
felled western hemlock trees were examined at four locations in B.C.: Kingfisher Creek
(10 trees) in the Kamloops Forest Region, Cranberry Creek (4 trees) and Red Rock
Harbour (5 trees) in the Nelson Forest Region, and Abbott Creek (7 trees) in the Cariboo
Forest Region. Average tree diameter at breast height was 43.0 cm (standard error 11.6).
Fach tree crown was divided into thirds and lichen samples were collected from each
third. The lichen samples were processed using the bleach extraction method and the
numbers of eggs found were standardized per 100 g dry weight of lichen. Numbers of
healthy (h), parasitized (p), infertile (1), new (h + p + i), and old eggs per 100 g dry
weight of lichen were transformed to logl0(x + 1) and compared for three crown levels
across the four locations by repeated measures analysis of variance (SAS 1985). Old eggs
are those from previous years whereas new eggs include healthy, parasitized and infertile
eggs from the current year.
Comparison of egg washing methods
Lichen was collected, using pole pruners, from 10 western hemlock trees in each of three
locations in the Nelson Forest District of B.C. Trees were a minimum of 25 cm diameter
at breast height, and enough lichen was collected to filla5 x 10 x 25 cm polyethylene
bag. The lichen from each tree was divided approximately in half and air dried in the
laboratory. One half of each lichen sample was processed using the hot water egg
extraction method and the other half was processed using the chlorine bleach extraction
method, both of which are described below. Egg counts were standardized by converting
them to per 100 g dry weight of lichen sample. Color, confirmed by other physical
characteristics (Thomson 1958), was used to classify the eggs as to type: healthy,
infertile, parasitized, or old (Table 1). For the non-destructive chlorine bleach extraction
method, a sample of these eggs was reared to confirm the classification. Rearing was
conducted on a moistened blotter in a screen vial which was kept at 0°C for two months
and then at 20°C until hatching was complete. Based on the rearing results the numbers of
healthy and parasitized eggs removed by the bleach method were corrected. The
numbers of WHL eggs of each type extracted by the two methods, were compared using a
paired t-test. The relationship between the number of healthy eggs extracted by the hot
water method and the number extracted by the bleach method was described by linear
regression.
32 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Table 1
Color characteristics of western hemlock looper egg types removed from lichen by the bleach
or hot water methods
Type of egg Bleach Method! Hot water method
Healthy Brown Bronze
Parasitized Black Black
Infertile Green Yellow
Old Opaque Opaque
1. From Otvos and Bryant (1972).
Hot Water Extraction Method:
Each lichen sample was placed in a 2 | plastic bucket. Water, heated to 100°C, was poured
over the sample until the lichen was immersed. The sample was swirled with tongs to
shake the eggs free of the lichen. The contents were then poured through nested strainers
consisting of a large meshed (1000 micron) top strainer to remove the debris but allow the
eggs through, and a close-meshed (250 micron) bottom strainer which retained the eggs.
The contents of the top strainer were rewashed to remove eggs which remained attached
during the first rinse. The bottom strainer was then inverted in a funnel and the contents
rinsed into a glass jar. Finally, the contents of the glass jar were extracted onto filter paper
using a vacuum filter. Egg counts were made by examining the filter paper with a
dissecting microscope.
Chiorine Bleach Extraction Method:
Lichen samples were teased apart, placed into a 2 1 plastic bucket and covered with a
solution of 2% chlorine bleach in water. The buckets were mechanically shaken at the
lowest setting for 45 minutes. Each sample was then processed as described for the hot
water method with the additional step of rinsing the contents of the bottom strainer with
tap water for 10 minutes to halt the corrosive action of the bleach.
RESULTS
Comparison of number of eggs at three tree crown levels
There were no significant differences among crown levels across the four locations for
either new (h + p + i) or old WHL eggs (Table 2). When the new eggs were analyzed
separately by type, no significant differences were found among crown levels for healthy
(P > .69), parasitized (P > .67), or infertile (P > .24) eggs. There were no significant
interactions between crown levels and location for any of the egg types (new: P > .89,
old: > .94, h: > .44, p:> .47, i: > .09).
Table 2
A comparison of the mean number of western hemlock looper eggs
per 100 gram lichen sample from three tree crown levels
Number Mean number of new eggs! (+ SEM)? Mean number of old eggs (+ SEM)?
Of ee EE eee
Location trees Uppercrown Midcrown Lowercrown Uppercrown Midcrown Lower crown
Kingfisher LO" 12-9 5.1 3.6+ 1.4 Tate 2325 23-7 ON 26.64 6.9 27.7+14.9
Cranberry AI 29. SOS Pissed Via y44! 23.2 2-120 198:0+32.6 © 125.4£28.2) 111,0=522%2
Red Rock > -345213.7 4 928: 82rd AIS 279.7 184:.2+89.0 197.2221.) = 9S 955
Abbott Tv WSS 10S: 61.679. 92.46.8599 49:2412.2_ ) 30.3210,0 72 Sheers
1. New eggs includes healthy, infertile and parasitized eggs of the current year.
2. No significant differences among crown levels were found within egg types across locations,
Repeated Measures ANOVA on data transformed to log,)(x + 1); new: F = .43; P > .65, old: F = .25, P > .78.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 33
Table 3
A comparison of the mean number of western hemlock looper eggs per 100 gram lichen sample
extracted from lichen by the bleach and hot water methods
Bleach method Hot water method
Type of Egg Mean! S.E.M. Mean! S.E.M.
Healthy 74.0 1267 122.6 WS
Parasitized 28.1 2.0 44.6 6.1
Infertile 29.8 4.2 53.9 6.5
Old? 66.8 7.8 118.7 16.1
New2 131.9 18.4 221.1 26.5
Total 198.8 25:2 339.8 41.0
1. Mean numbers of all types of eggs were significantly greater for the hot water method than the bleach
method, paired t-test, P< 0.01, n = 30.
2. Old eggs were those from previous years, new eggs included healthy, parasitized and infertile eggs from the
current year.
Comparison of egg extraction methods
There was no significant difference between the weights of the lichen sample halves
assigned to the bleach or hot water treatment (paired t-test, t = 1.17, n = 30).
Significantly more of all types of WHL eggs (healthy, parasitized, infertile, old, new
and total) were removed from the lichen substrate by the hot water method than by the
bleach method (Table 3).
The number of healthy eggs removed by the hot water method was regressed on the
number removed by the bleach method to provide an equation for converting egg
numbers derived from one extraction method to the other. A linear model was used and
three points were identified as outliers (Freund and Littell 1986) and removed from the
regression. As the intercept was not significantly different from zero (p > 0.2) the
regression was forced through the origin, producing the following relationship (R? =
0.89; s.e. slope 0.01):
No. healthy eggs (hot water) = 1.473 x No. healthy eggs (bleach)
The difference in color between healthy and parasitized eggs removed by the bleach
method is not so distinctive as for the hot water method. Of 180 “healthy” eggs reared,
parasitoids emerged from 26 indicating that 14.4% of the “healthy” eggs were mis-
classified. Misclassification cannot be quantified for the destructive hot water method;
however, because the color of the healthy egg type is more distinctive it is assumed that
misclassification is minimal. Support for this assumption can be found by comparing the
percentage of total eggs in each egg type extracted by the two methods. Initially, healthy
eggs represented a higher percentage and parasitized eggs represented a lower percent-
age of total eggs for the bleach method than for the hot water method (Fig. 1). However,
when the numbers of healthy and parasitized eggs extracted by bleach were corrected for
the 14.4% misclassification found in the rearing study, all egg types represented similar
percentages of the total number of eggs for both extraction methods (Fig. 1).
DISCUSSION
The finding that there were no significant differences between tree crown levels for
number of WHL eggs per 100 g lichen should simplify egg sampling procedures for this
insect species. In the past, trees frequently have been felled to obtain egg samples for
WHL from the upper part of the crown. Lower crown samples, which can usually be
collected with pole pruners, should provide reliable estimates of WHL egg density.
The hot water method was more efficient at removing WHL eggs from the lichen than
was the bleach method. As a result, when the insect is at low population densities, egg
counts obtained by the hot water method should be more sensitive than those obtained by
the bleach method. Also, the colors of the egg classes (h, p, i) were more distinctive with
34 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
ME HOT WATER METHOD
BLEACH METHOD
90 Sy BLEACH METHOD ADJUSTED
BY REARING RESULTS
(op)
e 40
LL
oO
a0
= 30
==)
=
pa |
=<
(ep)
ee)
(ee)
-_
=—
LL
2
ol 10
0 I
HEALTHY PARASITIZED INFERTILE OLD
EGG TYPE
Fig. 1. A comparison of the percentage of total western hemlock looper eggs that were healthy,
parasitized, infertile, or old, extracted by the bleach or hot water methods from lichen substrate.
hot water than with bleach and it seemed that misclassification was lower. For these
reasons, it is recommended that the hot water method be used when the objective is
relative population density estimation for damage prediction.
If the objective is to evaluate WHL egg mortality attributable to parasitism, and
species specific information about parasitoids is required, the bleach method should be
used. This method is non-destructive and therefore permits the user to rear the eggs to
confirm classification and to identify parasite species.
ACKNOWLEDGEMENTS
I thank the rangers of the Forest Insect and Disease Survey, Forestry Canada, Pacific and
Yukon Region, for technical assistance, Drs. R.I. Alfaro, J.W.E. Harris, and I.S. Otvos
for critical review of the manuscript, and Dr. C.S. Simmons for statistical advice.
REFERENCES
Carolin, V.M., N.E. Johnson, PE. Buffam, and D. McComb. 1964. Sampling egg populations of the western
hemlock looper in coastal forests. U.S.D.A. Forest Serv., Res. Pap. PNW-14, 13 pp.
Condrashoff, S.E 1967. An extraction method for rapid counts of insect eggs and small organisms. Can. Ent.
99:300-303.
Eidt, D.C.; Cameron, M.D. 1970. Pretreatment of spruce budworm eggs for counting. Can. For. Serv., Bi-
mon. Res. Notes 26:46-47.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 35
Freund, R.J. and R.C. Littell. 1986. SAS system for regression. SAS Institute Inc., Cary, N.C. 164 pp.
Gray, T.G.; Shepherd, R.E; Wood, C.S. 1973. A hot-water technique to remove insect eggs from foliage. Can.
For. Serv., Bi-mon. Res. Notes 29(5):29.
Harris, J.W.E., A.E Dawson, and R.G. Brown. 1982. The western hemlock looper in British Columbia 1911-
1980. Environ. Can., Can. For. Serv., Pac. For. Cent., Inf. Rept. BC-X-234, 18 pp.
Hopping, G.R. 1934. An account of the western hemlock looper, Ellopia somniaria Hulst, on conifers in
British Columbia. Scientific Agriculture XV:12-27.
Kinghorn, J.M. 1952. Western hemlock looper egg sampling. Can. Dep. Agric., Bi-mon. Prog. Rept. 8(3):3-
4.
Kinghorn, J.M. 1954. The effect of stand composition on the mortality of various conifers, caused by
defoliation by the western hemlock looper on Vancouver Island, British Columbia. For. Chron. 30(4):380-
400.
Otvos, I.S. and D.G. Bryant. 1972. An extraction method for rapid sampling of eastern hemlock looper eggs,
Lambdina fiscellaria fiscellaria (Lepidoptera: Geometridae). Can. Ent. 104:1511-1514.
Richmond, H.A. 1947. Current trend of the western hemlock looper (Lambdina f. lugubrosa) in the coastal
forest of British Columbia (Lepidoptera: Geometridae). Entomol. Soc. of British Columbia, Proc. (1946)
43:33-35.
SAS Institute Inc., 1985. SAS users guide: Statistics, Version 5 Edition. Cary, NC:SAS Institute Inc., 956 pp.
Shepherd, R.F and T.G. Gray. 1972. Solution separation and maximum likelihood density estimates of
hemlock looper (Lepidoptera: Geometridae) eggs in moss. Can. Ent. 104:751-754.
Shore, T.L. 1989. Sampling western hemlock looper pupae (Lepidoptera: Geometridae) using burlap traps. J.
Entomol. Sci. 24(3):348-354.
Thomson, M.G. 1949. Determination of larval populations of forest defoliators by frass fall and body weight,
with particular reference to the western hemlock looper. Can. Dep. Agric., Sci. Serv., Div. For. Biol, For.
Biol. Lab. Victoria, B.C. 49 pp.
Thomson, M.G. 1957. Appraisal of western hemlock looper infestations. For. Chron. 33(2):141-147.
Thomson, M.G. 1958. Egg sampling for the western hemlock looper. For. Chron. 34(3):248-256.
Wyatt, G.R. 1946. Hemlock looper: history of outbreaks on the Pacific coast. Can. Dep. Agric., Science Serv.,
Div. For. Biol., For. Biol. Lab., Victoria, B.C., Interim Tech. Rep. 8 pp.
A review of mosquito collecting in the Yukon
E.M. BELTON and P. BELTON
CENTRE FOR PEST MANAGEMENT
DEPARTMENT OF BIOLOGICAL SCIENCES
SIMON FRASER UNIVERSITY
BURNABY, B.C. VSA 186
The first formal record of a mosquito collected in the Yukon was in 1904 when J. Keele
caught Anopheles occidentalis in the Mayo River valley (Dyar 1921). In 1916 three
females of Aedes nearcticus were collected on Herschel Island, off the north coast of the
Yukon, by Frits Johansen of the Canadian Arctic Expedition (Dyar 1919). These species,
now known as An. earlei and Ae. impiger respectively, were identified at the time by Dr.
Harrison Dyar at the United States National Museum in Washington.
Dyar, himself, visited the Yukon in June and July of 1919. He travelled from Carcross
in the south, along the Yukon valley to Dawson which is less than half way to Herschel
Island. He recorded 16 species (Dyar 1920, 1921) including nearly 2,000 specimens of
Ae. cataphylla which he found to be the dominant species with Ae. campestris, Ae.
communis and Ae. punctor also common (Table 1). He described three new species from
his Yukon material: Ae. nearcticus from Herschel Island, the Northwest Territories and
Alaska (Dyar 1919); Ae. callithotrys from Whitehorse and Takheena River in the Yukon
and from Alaska; and Ae. mercurator from 65 specimens collected around Dawson (Dyar
1920). He later synonymised Ae. callithotrys with Ae. campestris (Dyar 1928).
36 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
By the 1920s Whitehorse was attracting tourists and, in 1926, presumably as a result
of their complaints, Eric Hearle, who had already reduced the mosquito nuisance in the
Lower Fraser Valley of B.C. and the resorts of Banff and Lake Louise in Alberta, was
invited to make recommendations on controlling mosquitoes in the Yukon (Hearle 1927).
He probably collected adults and larvae when he assessed the problem around White-
horse.
The Dominion Entomologist, Arthur Gibson, reported on mosquito control in Canada
from 1923-1941 to the Annual Meetings of the New Jersey Mosquito Control Associa-
tion, but did not refer to any work in the Yukon.
From 1947 to 1950, mosquitoes were collected from several arctic and subarctic
localities as part of the Northern Insect Survey, a joint endeavour of the Canada
Department of Agriculture and the Department of National Defense. An Interim Report
by Freeman (1952) of the mosquitoes obtained during the Survey consisted mainly of
distribution maps. The 16 species reared from sites in the Yukon were mainly from
Dawson or Whitehorse. Vockeroth (1954a) addressed the difficult problem of identifying
the females and discussed their distribution. Ae. nigripes was not found in the Yukon
during the Survey but he thought it was probably present because it is the most abundant
species elsewhere in the arctic. Vockeroth (1954b) examined the type specimens of
several arctic species. He pointed out that mosquitoes identified up to that time as Ae.
nearcticus were in fact Ae. impiger and that the specimens from Dawson and elsewhere,
identified in the Canadian National Collection as Ae. impiger, belonged to a new species
which he described and named Ae. implicatus.
In his guide to the mosquito larvae of Western Canada, Rempel (1950) noted that 8 to
10 of the species in the guide occurred in the Yukon. He did not refer to collecting there
himself but he may have seen representative specimens in collections loaned to him from
the Canadian National Collection in Ottawa and the U.S. National Museum in Washing-
ton.
In the summers of 1949 and 1950, Colin Curtis, an entomologist from the Veterinary
and Medical Entomology Laboratory at Kamloops, B.C., collected 21 species around
Whitehorse and Watson Lake (Table 1). He noted that although Ae. cataphylla was
common, the predominant pest mosquitoes were Ae. communis followed by Ae. punctor
and Ae. pionips (Curtis 1953).
Dr. D.M. McLean, a medical microbiologist from the University of British Columbia,
collected mosquitoes in northern B.C. and the Yukon during several seasons in a survey
for mosquito-borne encephalitis viruses. He collected mainly adults and some larvae at
about a dozen locations in the boreal forest region from Marsh Lake near Whitehorse in
the southeast to an area near the Dempster Highway at 67°N and 137°W. He found seven
species infected with viruses: Ae. canadensis, Ae. cinereus, Ae. communis, Ae. hexo-
dontus, Ae. nigripes, Ae. punctor, and Cs. inornata (McLean, Judd & Shives 1981;
McLean & Lester 1984).
One of the largest collections of mosquitoes from the Yukon was made in 1972 and
1973 by John Nelson, a Master of Pest Management student at Simon Fraser University,
Burnaby, B.C. He set up New Jersey light traps and bite sampling stations at 28 sites from
Watson Lake in the south to Old Crow within the Arctic Circle (Nelson 1977). Of about
27,000 specimens caught by him in 1972, the commonest biting species were Ae.
pionips, Ae. hexodontus, Ae. cataphylla, Ae. communis, Ae. campestris, and Ae.
nigripes, in that order, although it probably varied considerably from place to place. In
addition to many of the species found by Dyar and Curtis, he listed nine more, five of
them verified by Wood, Dang & Ellis (1979) and Wood (1989, personal communication),
and four others, three of which are probably correct (Table 1), bringing the number of
mosquito species in the Territory to about 30.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 a7
REFERENCES
Curtis, L.C. 1953. Observations on mosquitoes at Whitehorse, Yukon Territory. Diptera: Culicidae. Can. Ent.
85:353-370.
Dyar, H.G. 1919. The mosquitoes collected by the Canadian Arctic Expedition, 1913-18. Rept. Can. Arctic
Expedn. III, pt C:31-33.
Dyar, H.G. 1920. The mosquitoes of British Columbia and the Yukon Territory, Canada. Insecutor Inscit.
menstr. 8:1-27.
Dyar, H.G. 1921. The mosquitoes of Canada. Trans. R. Can. Inst. 13:71-120.
Dyar, H.G. 1928. The mosquitoes of the Americas. Carnegie Inst. Wash. Publ. 387:1-616.
Freeman, T.N. 1952. Interim Report of the distribution of the mosquitoes obtained in the Northern Insect
Survey. Defense Research Board of Ottawa. Tech. Rep. 1. 2pp. 43 maps.
Hearle, E. 1927. Mosquito control activities in Western Canada. Ann. Rep. Ent. Soc. Ont. 58:45-S0.
McLean, D.M., B.D. Judd & S.K.A. Shives. 1981. Snowshoe hare virus infections in Canadian Arctic
mosquitoes during 1980. Mosq. News 41:287-—290.
McLean, D.M. & S.A. Lester. 1984. Isolations of Snowshoe hare virus from the Yukon mosquitoes, 1983.
Mosq. News 44:200-203.
Nelson, J. 1977. Mosquito control in the Yukon Territory, Canada. MPM Thesis, Simon Fraser Univ., Can. pp.
111.
Rempel, J.G. 1950. A guide to the mosquito larvae of western Canada. Can. J. Res. D, 28:207-248.
Vockeroth, J.R. 1954a. Notes on the identities and distribution of Aedes species of northern Canada, with a key
to the females (Diptera, Culicidae). Can. Ent. 86:241-255.
Vockeroth, J.R. 1954b. Notes on northern species of Aedes, with descriptions of two new species (Diptera,
Culicidae). Can. Ent. 86:109-116.
Wood, D.M., PT. Dang & R.A. Ellis. 1979. The Mosquitoes of Canada. Diptera: Culicidae. The Insects and
Arachnids of Canada. Part 6. Agric. Can. Publ. 1686. pp. 390.
Table 1
Mosquitoes recorded from the Yukon Territory
Dyar’s species Cs. incidens
Anopheles earlei (occidentalis*) Cs. morsitans (dyari*)
Aedes campestris (callithotrys*)
Ae. cataphylla
Ae. cinereus
Ae. communis
Ae. excrucians
Ae. fitchii
Ae. impiger (nearcticus* )
Ae. mercurator
Curtis’s additional species
Ae. canadensis
Ae. diantaeus
Ae. flavescens
Ae. hexodontus
Ae. nigripes
Ae. riparius
Culex territans (apicalis*)
Ae. pionips
Ae. pullatus Nelson’s additionai species
Ae. punctor Ae. decticus
Ae. stimulans (Dyar’s reference to it in the Yukon Ae. intrudens
should probably be to Ae. mercurator Wood, Ae. implicatus
Dang & Ellis 1979) Ae. vexans
Culiseta alaskaensis Cs. inornata
Cs. impatiens
The following 4 of Nelson’s species were not recorded as occurring in the Yukon by Wood, Dang & Ellis 1979
and Wood, 1989, Personal Communication. The last three probably do occur there, but Ae. sticticus has not
been found north of Terrace, B.C., in Western Canada.
Ae. sticticus Ae. provocans
Ae. euedes Cx. tarsalis
* Names in parentheses were used in the publications referred to in the text.
38 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Response of Frankliniella occidentalis (Thysanoptera: Thripidae)
and Trialeurodes vaporariorum (Homoptera: Aleyrodidae) to
fluorescent traps in a cucumber greenhouse
ROBERT S. VERNON
AGRICULTURE CANADA RESEARCH STATION
6660 N.W. MARINE DRIVE, VANCOUVER, B.C. V6T 1X2
DAVID R. GILLESPIE
AGRICULTURE CANADA RESEARCH STATION
P.O. BOX 1000, AGASSIZ, B.C. VOM 1A0
ABSTRACT
This paper describes the responsiveness of the western flower thrips, Frankliniella
occidentalis (Pergande) and the greenhouse whitefly, Trialeurodes vaporariorum (West-
wood) to fluorescent and non-fluorescent colored sticky traps in a cucumber greenhouse.
As in previous studies, thrips preferred blue, white or yellow painted traps. The fluores-
cent pigments Horizon Blue, Saturn Yellow and Arc Yellow were not significantly
different in attractiveness from non-fluorescent blue and yellow pigments. Whiteflies
preferred non-fluorescent yellow, Saturn Yellow, Arc Yellow and Signal Green traps over
the other colors tested. Where a single trap color is desired for sampling both pest species,
a yellow pigment with high reflective intensity around 550 nm is recommended.
INTRODUCTION
In greenhouses, the western flower thrips, Frankliniella occidentalis (Pergande) prefer-
entially alights on traps painted white, blue or yellow (Vernon and Gillespie, 1990;
Brodesgaard, 1989). The degree of response to painted traps has been shown to depend
on interactions between wavelengths reflected at 350 nm (ultraviolet), 440 nm (blue) and
550 nm (yellow) (Vernon and Gillespie, 1990). Blue traps attract optimally when the
reflectance intensity at 440 nm is high, and the reflectance intensities at 350 and 550 nm
are low. Conversely, yellow traps are attractive, but only if wavelength reflectance
intensity at 550 nm is above 60 percent, and if reflectance intensities at 350 and 440 nm
are low. White traps are attractive to thrips at high reflectance intensities of wavelengths
between 400-650 nm, but lose attractiveness with the gradual addition of black or UV.
The multiple regression models derived to explain the relationships between wave-
length and thrips response (Vernon and Gillespie, 1990) suggest that blue and yellow
traps with an increasing proportion of attractive wavelengths (440 nm and 550 nm,
respectively) to non-attractive wavelengths, will be increasingly attractive to F. occiden-
talis. This also suggests that fluorescent blue and yellow pigments, being highly
reflective at wavelengths 440 nm and 550 nm, may be more attractive to F. occidentalis
than the non-fluorescent paints tested by Vernon and Gillespie (1990).
This paper investigates the attractiveness of fluorescent versus non-fluorescent paints
to F: occidentalis in a cucumber greenhouse. In addition, the attractiveness of these
paints to the greenhouse whitefly, Trialeurodes vaporariorum (Westwood), is examined
with the objective of selecting a single color for simultaneous monitoring of both
species.
MATERIALS AND METHODS
The non-fluorescent paints blue 871, yellow 776 and white semi-gloss enamel (Clover-
dale Paint and Chemicals Ltd., Surrey, B.C. V8W4Z1, Canada) were applied in two coats
to one side of a sheet of white cardboard (56 by 72 cm; 4-ply Railroad Board, Domtar
Fine Papers, Toronto, Ontario). The fluorescent paints Rocket Red, Arc Yellow, Saturn
Yellow, Signal Green and Horizon Blue (Day-Glo, Color Corporation, Cleveland, Ohio,
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 39
Table 1
Trap catch response of western flower thrips, Frankliniella occidentalis and greenhouse whiteflies,
Trialeurodes vaporariorum on 5 fluorescent and 3 non-fluorescent colored sticky traps. Studies were
conducted in a cucumber greenhouse from 21-22 August, 1989.
F. occidentalis! T. vaporariorum!
Sex Ratio
COLOR: Females SE. Males S.E. M:F Mean S.E.
Rocket Red 9.5a 1.20 0.8 a 0.25 111.9 0.3 a 0.15
Arc Yellow 19.8b 1.84 2.6b 0.40 1:7.6 4.0b 1.20
Saturn Yellow 29.7 ed 2.50 7.0c 1.45 1:4.2 iisbec 3.52
Signal Green 8.0 a 0.80 0.9 a 0.41 1:8.9 14.3 c¢ 6.73
Horizon Blue Veows 7.91 6.2¢c 1.16 Pi2e2 0.0a 0.00
Yellow 776 23.3 DC 2.66 3.9 be 0.59 1:6.0 14.1lc¢c Doe
Blue 871 73.4€ 10.18 4.8 be 1.10 Be ie) 0.0a 0.00
Non-UV White 40.9 d 5321 6.8c¢ 1.24 1:6.0 0.5a 0.27
1. Means followed by the same letter within a column are not significantly different (Duncan’s multiple range
test; P = .05).
44103) were applied in one coat to cardboard previously painted with one coat of white
semi-gloss enamel. The spectral reflectance profiles (350-700 nm) of all non-fluorescent
colors used was measured relative to a white magnesium oxide standard using a Cary 17
recording spectrophotometer. Reflectance spectra for the fluorescent colors were
obtained from the manufacturer and all spectra are shown in Fig. 1. The painted sheets
were cut into 8.5 xX 17 cm rectangles, folded into squares, and coated with Stikem _
Special (Seabright Enterprises, Emeryville, CA, 94608).
The study was done from 21-22 August, 1989 in a commercial cucumber greenhouse
infested with F: occidentalis and T. vaporariorum. The traps were clipped to the top 8.5
cm of upright 1 x 3 x 30cm garden lathes which were fixed 38 cm apart to a horizontal 4
x 4 x 300 cm board. These trap stands, painted black, were positioned above and
between two rows of mature cucumbers. Traps were 2.4 m above ground and 0.6 m above
the crop, with opposing sticky sides facing north and south. The experiment was
conducted using a randomized complete block design with ten replicates. Transmission
of light through a sample of the greenhouse glass was measured previously (Vernon and
Gillespie, 1990), and was from 90 to 97% efficient in transmitting wavelengths between
350-700 nm. Transmission of higher energy UV wavelengths dropped sigmoidally from
90% at 350 nm to 0% at 300 nm.
Data were subjected to an analysis of variance after log10 (X + 1) transformation, and
means were ranked by Duncan’s (1955) multiple range test at P = 0.05.
RESULTS AND DISCUSSION
Significant differences in alighting by F. occidentalis on the 8 different colored traps
were observed for males (F = 16.19; df 7,63; P = .0001) and females (F = 63.23; df 7,
63; P = .0001). Of the non-fluorescent colors, blue 871 traps caught significantly more
females than yellow 776 or white traps (Table 1). This result is consistent with the results
of Vernon and Gillespie (1990), who tested the same colors in the same greenhouse. The
fluorescent pigments Horizon Blue, Saturn Yellow and Arc Yellow were not significantly
different from their non-fluorescent blue and yellow counterparts. Signal Green and
Rocket Red were the least attractive pigments tested. Similar trends in trap preference
were evident for males, except that significant differences were not observed in
alightment on the yellow (except Arc Yellow), blue and white traps (Table 1). The male to
female sex ratios captured on the fluorescent and non-fluorescent blue traps were higher
than those occurring on the yellow and white traps (Table 1). Similar sex ratios were
observed on non-fluorescent blue, yellow, and white traps previously tested at the same
time of the previous year by Vernon and Gillespie (1990). Reasons for these color specific
40 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
PERCENT REFLECTION
2
WAVELENGTH (nm)
Fig. 1. Spectral reflectance curves of 5 fluorescent and 3 non-fluorescent color pigments used in
trapping F. occidantalis and T. vaporariorum in a cucumber greenhouse. The codes used are: R.R.
= Rocket Red; A. Y. = Arc Yellow; S.Y. = Saturn Yellow; S.G. = Signal Green; H.B. = Horizon
Blue; WT = non-fluorescent white; B871 = non-fluorescent blue; and Y776 = non-fluorescent
yellow.
differences in sex ratio are not known. The results reported herein as well as those of
Vernon and Gillespie (1990), however, suggest that subtle differences in color preference
or visual behavior may exist between males and females.
The regression models proposed for the attraction of F: occidentalis to colored traps
(Vernon and Gillespie, 1990), predicted that blue 871 and yellow 776 would be,
respectively, 1.82 and 1.05 times more attractive than white. In this study, blue 871 and
yellow 776 caught, respectively, 1.84 and 0.57 times more thrips than white traps. The
catch on blue 871 traps was closely predicted, but the catch on yellow was lower than
predicted, and was considerably lower relative to white than in 12 studies conducted
previously (Vernon and Gillespie, 1990; Gillespie and Vernon, 1990; Gillespie, un-
published data). This atypical response to yellow could indicate that the relative response
of thrips to yellow and white may be influenced by unknown biotic or abiotic factors
presently not considered in the prediction models. Using the manufacturers’ spectral
reflectance data for Horizon Blue and Saturn Yellow (Fig. 1), the regression models
predicted much higher trap responses than actually occurred (1.e., 91.8 and 288.4 times
more attractive than white traps, respectively). This may indicate that there is an upper
threshold for thrips’ visual attraction to blue and yellow colored traps, and that the
reflective intensities (RI) of key wavelengths in Horizon Blue and Saturn Yellow, along
with their counterparts blue 871 and yellow 776 were at or near to this threshold.
Significant differences (F = 29.26; df 7, 63; P = .0001) in catches of 7: vaporariorum
on the 8 color traps were also observed. Yellow 776, Signal Green, Saturn Yellow and
Arc Yellow, with peak RIs between 520 and 590 nm (Fig. 1), were significantly more
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 4]
attractive than Rocket Red, Horizon Blue, blue 871 and white. Saturn Yellow (Peak RI =
527 nm), Signal Green (Peak RI = 518 nm) and yellow 776 (Peak RI = 550 nm) were
equivalent in attraction, but significantly more attractive than Arc Yellow (Peak RI =
595 nm). These results compare favorably with those of Vaishampayan et al. (1975) who
found T. varporariorum was most attracted to surfaces with peak RI in the “‘yellow-
green” region (520-610 nm), and that the “*blue-violet” (400-480 nm) and “red” (610-—
700 nm) spectral regions were not attractive and possibly inhibitory to alightment. Our
work also compares with that of Affeldt et al. (1983), who found that fluorescent Saturn
Yellow and Signal Green traps were not significantly different in catches of T. vapor-
ariorum, and that these colors were not significantly better than non-fluorescent yellow
traps.
These data indicate that blue, yellow and white colored traps are adequate for trapping
F- occidentalis, and that traps with peak RI between 520-550 (green-yellow) are most
attractive for trapping T. vaporariorium in greenhouse. Where a single trap is desired for
sampling both species, a yellow hue with high RI between 530-550 is preferred.
Fluorescent paints, which are more expensive than non-fluorescent paints, would not
contribute significantly to the trapping of either species in greenhouses.
LITERATURE CITED
Affeldt, H.A., R.W. Thimijan, EE Smith and R.E. Webb. 1983. Response of the greenhouse whitefly
(Homoptera: Aleyrodidae) and the vegetable leafminer (Diptera: Agromyzidae) to photospectra. J. Econ.
Ent. 76:1405-1409.
Brodesgaard, H.F 1989. Coloured sticky traps for Frankliniella occidentalis (Pergande) (Thysanoptera,
Thripidae) in glasshouses. J. Appl. Ent. 197:136-140.
Duncan, D.B. 1955. Multiple range and multiple F tests. Biometrics 11:1—42.
Gillespie, D.R. and R.S. Vernon. 1990. Trap catch of western flower thrips, Frankliniella occidentalis
(Thysanoptera: Thripidae), as affected by color and height of sticky traps in greenhouses. J. Econ.
Entomol. 83:971-975.
Vaishampayan, S.M., M. Kogan, G.P. Waldbauer and J.T. Woolley. 1975. Spectral specific responses in the
visual behaviour of the greenhouse whitefly, Trialeurodes vaporariorum (Homoptera: Aleyrodidae).
Entomol. Exp. Appl. 18:344-356.
Vernon, R.S. and D.R. Gillespie. 1990. Spectral responsiveness of Frankliniella occidentalis (Pergande)
(Thysanoptera: Thripidae) determined by trap catches in greenhouses. Environ. Entomol. 19:1229-1241.
Observations on the biology of the bronze flea beetle Altica
tombacina (Coleoptera: Chrysomelidae) in British Columbia
J.P. MICHAUD
DEPARTMENT OF BIOLOGICAL SCIENCES
SIMON FRASER UNIVERSITY
BURNABY, B.C. V5A 1S6
ABSTRACT
Populations of A. tombacina were monitored for 2 years at three field sites of varying
elevation on Vancouver Island. In 1988, population densities of overwintered adults were
greatest at the middle elevation (615m) followed by the highest (830m) and lowest at the
low elevation (185m). Egg densities remained below 10/m2 at 185m but exceeded 200/m2
in places at 615m and 400/m2 at 830m. Egg mortality was exceedingly high at all sites
ranging from 98% at 185m, 95% at 615m and 99% at 830m; very few larvae appeared to
survive. Only 2 adults were counted the following spring at the lowest elevation where
eggs and larvae were exceedingly difficult to find. No life stages could be found at either
of the higher elevation sites. Cold weather early in June, 1988, appeared to be responsible
42 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
for this population decline. Overwintered adults of A. tombacina were also reared in the
laboratory at constant temperatures of 18° and 25°C. The rate of oviposition was greater
by a factor of 2 at the higher temperature. The egg-adult survival rate was approximately
15% at 25°C and there was no completed development at 18°. Each larva surviving to
pupation consumed a mean of about 28mg. dry weight of leaf.
INTRODUCTION
The bronze flea beetle, Altica tombacina Mannerheim (Coleoptera: Chrysomelidae), is a
common inhabitant of early successional communities of the Pacific northwest from
Oregon to British Columbia. Its natural host is fireweed, Epilobium angustifolium L.
(Onagrcaeae), but it has also been described as a pest of strawberry and roses (Dirks-
Edmunds 1965). The Altica-Epilobium relationship is probably a very ancient one.
Closely related species, e.g. A. lythri Aube, A. oleracea L. and A. palustris L., are also
found in the old world associated with various Epilobium spp. (Phillips 1977, Port &
Guile 1986).
In temperate regions the Alticinae are almost exclusively monovoltine and overwinter
as adults in the plant litter. Phillips (1977) noted that a second period of oviposition
sometimes occurred in various old-world species. Dirks-Edmunds (1965) stated that the
progeny of lab-reared A. tombacina collected in Oregon began reproduction without
diapause, a fact suggesting that bivoltinism may be facultative in this species. Adult sex
ratios commonly range from 5:1 to >15:1 in favor of females according to my own
observations. Skewed sex ratios apparently occur frequently in the Alticinae. Port &
Guile (1986) have reported sex ratios exceeding 6:1 for Altica britteni (Sharp) and A.
ericeti (Allard) in Great Britain.
The life history of A. tombacina has been described by Dirks-Edmunds (1965) and is
not dissimilar from that of other new world Alticinae (Woods 1918). There are three
larval instars; both adults and larvae feed in exposed locations on the foliage of their host
plant. Under optimal conditions eggs hatch in 3 to 5 days and the larvae feed for 12 to 14
days before pupating. Pupation requires another 10 to 14 days after which adults eclose
and feed briefly before dispersing. In late summer, the quality of fireweed foliage
declines and aggregations of beetles can sometimes be found feeding on the buds and
tender bark of red alder, Alnus rubra L.
A common feature of most Altica species appears to be marked and unpredictable
fluctuations in population density (Woods 1918, Port & Guile 1986). Large populations
occasionally result in severe defoliation of the host plants, primarily as a result of feeding
by larvae. In the case of A. tombacina this has been cause for concern among apiarists in
British Columbia who rely upon fireweed for a valuable midsummer honey flow.
Defoliation by larvae can inhibit flowering (Michaud 1990) and reduce nectar secretion
(Michaud 1989), even causing the die-back of entire shoots (Atkins 1964).
The following study was designed to observe the trajectories of three field populations
over 2 years and to establish techniques for rearing the flea beetles in the laboratory. I also
wanted to test the effects of temperature on oviposition rate and the survival of eggs,
larvae and pupae and to estimate larval consumption.
MATERIALS AND METHODS
Three sites varying in elevation were selected for study near Lake Cowichan, Vancouver
Island. Quadrats of 2m? were staked out in early May, 1988, as the first over-wintered
adults emerged. Site 1 was at an elevation of 185m a.s.l. near the lake shore and five
quadrats were located here. Sites 2 and 3 were located 20 km west of the lake at elevations
of 615m and 830m, respectively. Ten quadrats were placed at each of these two sites. All
three sites were relatively recent clear-cuts that had been replanted to Douglas fir,
Pseudotsuga menziesii (Mirb.) Franco within the last 3 years. All quadrats were
examined at 10-12 day intervals and the beetle’s life stages were tallied (adults, eggs and
larvae). Pupation is subterranean and pupae were not counted.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 43
FIGURE 1 FIGURE 2
site 1, 1988 Dive 2.1900
- N = 119 Shoots bee N= 371 Shoots
80
Legend
Legend
Cae © ADULTS e
c A EGGS o ae © ADULTS
Seer O LARVAE = A EGGS x10_
fe) fe) O LARVAE
Zi a eae
je c 40
©) e)
; 20
a aa, = oY a oe oe aha as
os (aes \ a Ne a XN
wes Oy py Oe es ye yr Lew
Sampling Date Sampling Date
Fig. 1. Population trajectory of A. tombacina at site 1 (el. 185m) in 1988 showing emergence of
over-wintered adults, oviposition, and appearance of larvae.
Fig. 2. Population trajectory of A. tombacina at site 2 (el. 615m) in 1988 showing emergence of
over-wintered adults, oviposition, and appearance of larvae.
Several hundred overwintered adults were collected during the last week of April at a
number of roadside sites in Burnaby, B.C. Specimens of A. tombacina were identified by
L. LeSage of the Biosystematics Research Institute, Ottawa, Ontario, where voucher
speciments were consigned. A number of different enclosures were tested for suitability
in rearing the insects. Large ventilated plastic petri dishes were finally employed with a
layer of moist sand covered by filter paper. Fresh leaves were provided every 2 days and
appeared to remain acceptable as food over this time. There remained the problem of
containment while food and filter paper were being changed. This procedure was best
accomplished within the confines of a conventional plexiglass insect cage so that
escapees could be readily caught and returned to their respective containers. Larvae
were reared in similar containers and they pupated in the moist sand beneath.
To assess the influence of temperature on reproductive rate, two separate colonies of
overwintered adults were established. Beetles were sexed on the basis of size (males are
generally much smaller) and by separating pairs observed in copula. Each colony was
adjusted to contain 35 females and 15 males. One colony was maintained in a greenhouse
where the temperature averaged 25° (+ 4°) and the other in a growth chamber at
17° (+ 2°). RH was maintained as close as possible to 80% in both treatments but
sometimes dropped as low as 60% in the greenhouse. Fresh leaves of fireweed were
provided every 2 days, and all eggs removed and counted. This experiment was begun on
April 29 and ended on May 27.
Some of the eggs were collected, placed into separate dishes, and maintained under
the same thermal regime as their respective parental colonies. As the larvae hatched,
they were transferred to a series of dishes with fresh leaves. Mature larvae usually found
their way under the filter paper to burrow and pupate in the moist sand, although some
did so directly on the surface of the paper. As the adults eclosed, they were transferred to
another series of dishes, also provisioned with fresh leaves.
44 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
FIGURE 3
Site 3. 1988 FIGURE 4
N = 535 Shoots
Area = 20 Sqm
30
ZS
Legend
= 20 © ADULTS 4
‘OF A EGGS x10 oO
(Cp) —eo O
=< O LARVAE 5
5 8 a et Ae
Zz ee
S is
£ 10 a4
5 -2-4
oe 7 Y aia T Pr 1
a ee 2 ea G =5 3 5 7
p ws o S
») . 9 . In (mean)
Sampling Date
Fig. 3. Population trajectory of A. tombacina at site 3 (el. 830m) in 1988 showing emergence of
over-wintered adults, oviposition, and appearance of larvae.
Fig. 4. Data for site 2 (el. 615m) on May 25, 1988 plotted as In(variance) #’s of adults/shoot against
In(mean) showing a significant departure from random distribution (regression line slope = 2).
To assess larval consumption, 60 Ist-instar larvae were segregated into various dishes
immediately upon hatching. Fresh leaves were weighed before they were given to the
larvae, and again upon removal 2 days later. The 25° temperature regime was used
because it appeared to be the most favorable for development. Fresh leaves lost 24.6% of
their original weight due to moisture loss over the 2 day period under these conditions.
Fresh leaves contained a mean of 78.2% water by weight. Mean consumption per larvae
surviving to pupation was then determined according to the following equation:
X[(wi — wo X mlc—!) x dwe](#1)—!
Wi = weight in (grams)
wo = weight out (grams)
mlc = moisture loss constant = .754
dwc = dry weight conversion factor = .218
#1 = number of larvae alive
RESULTS AND DISCUSSION
The patterns of emergence of overwintered adults, oviposition and appearance of larvae
in 1988 are represented in Figs. 1-3 by mean densities for each sampling date on a site by
site basis. The exact numbers of adults, eggs and larvae respectively counted on each
sample date, quadrat by quadrat, are reported in the Appendix. It should be noted that
counts of ‘0’ adults occurred for all quadrats on June 3 because wind and rain during the
previous 24 hours drove all insects to seek shelter in the litter.
Adults displayed a highly clustered distribution on shoots. For example, at quadrat 4
on May 24, 159 adults were counted. Of the 40 shoots of fireweed in quadrat 4, site 2,
only 22 had beetles residing on them. Of these 22 shoots, one had 71 adults, one 16, and
one 12. The remainder had fewer than 10 per shoot but only 3 had a single occupant.
Likewise at quadrat 3, site 2 on the same sampling date, of the 110 adults counted on 43
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 45
PICU ES
in (variance)
In (mean)
Fig. 5. Data for sites 2 (el. 615m) & 3 (el. 830m) on June 15, 1988 plotted as In(variance) of #’s of
eggs/shoot against In(mean) showing a significant departure from random distribution (regression
line slope = 2.26).
shoots, 85 occurred on 2 plants. Fig. 4 illustrates the clumping of adults with a plot of
In(variance) vs In(mean) using data from each quadrat at site 2 in which adults were
counted on May 25, 1988. The slope of the regression line is 2 and indicates a
distribution significantly more clumped than random (slope = 1). This clumping of
adults may be related to the low frequency of males that forces females to congregate. A
sex ratio estimate based on a dissected sample of some 200 beetles collected on the same
date indicated that females out-numbered males 15:1 in this population. This skew in the
sex ratio must dictate a polygamous mating system, which in turn results in a highly
clumped distribution of overwintered individuals.
Ovipositing females similarly appeared to favor particular shoots. On June 3, 1988,
2704 eggs were counted quadrat 4 of site 2. Of these, 1900 (70%) occurred on only 17%
of the 40 available shoots. On June 14, 4791 eggs were counted in this quadrat, 88% of
which occurred on 18 shoots. Fig. 5 illustrates the clumping of eggs on shoots with a plot
of In(variance) vs In(mean) using data from sites 2 and 3 on June 15, 1988. The
regression line slope is 2.26 and indicates a distribution significantly more clumped than
random.
Dividing the total numbers of eggs by total numbers of Ist-instar larvae provided a
rough estimate of the mortality rate of eggs: 95% in site 1, 99% in site 2, and 98% in site
3. The primary cause of mortality appeared to be cold weather. Many eggs never hatched
but eventually darkened and decayed. The remainders of egg casings adhering to leaves
provided evidence of some predation, while other eggs had been drained of their
contents, presumably by some insect with sucking mouthparts.
Most larvae appeared to die in the first instar and left only small feeding scars on the
undersides of leaves. I again suspected that cold weather was the primary cause of
mortality. Apart from direct effects on survival, cold weather seemed to slow the
development and growth of both eggs and larvae, probably rendering them more
vulnerable to predation. Fig. 6 charts the trajectory of mean daily temperature during the
period of egg and larval development. During the last week of May and the first week of
46 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
FIGURE? 6
20
AN
© [f\
AN
oO
= ifs)
ee)
oe)
\
() AN
Q.
eS
©
c 10
2 Legend
A 1988
x AVERAGE
5
2 q . 8 : : =
= 3
Fig. 6. Trajectory of mean daily temperature in °C for Lake Cowichan during spring of 1988 plotted
with normal values for the period.
June, mean temperatures averaged some 3-4°C below normals and daily maxima
remained below 19°.
No adults were observed after July 22, indicating that by this time the overwintered
cohort was dead. However, the possible emergence of some callow adults may have gone
undetected. Based on laboratory observations these tend to be reclusive and spend most
of the time hiding under leaf litter, emerging occasionally to feed. This is also the stage
when most dispersal appears to occur and during which adults can occasionally be found
feeding on alternate hosts such as Alnus rubra. In 1989, only two adults were observed at
site 1 and, subsequently, a few eggs and larvae. No life stages were encountered at sites 2
or 3 despite extensive searches. Cursory observation of roadside populations on the B.C.
lower mainland over some 4 years revealed that mainland populations did not appear to
undergo population fluctuations similar to those observed on Vancouver Island, but
appeared to remain stable at very moderate densities.
Ovipositing beetles in the laboratory colonies laid slightly more than twice as many
eggs (2954) at 25° as they did during the same period at 18° (1390) (one-way ANOvA, P <
0.01). Greenhouse temperature oscillated by +4° about a mean of 25° so it may be
concluded that temperatures up to 30° are stimulatory to oviposition relative to lower
temperatures.
A total of 650 eggs was incubated at 18° but only four of these hatched, for a survival
rate of < 0.1%. Many became covered with a white mycelial growth, although it could
not be determined if fungal infection was the cause of death. The four larvae that hatched
were transferred to a clean dish and given fresh leaves but they fed little and grew slowly,
dying in the second instar.
A total of 457 eggs was incubated at 25°C of which 160 hatched for a survival rate of
35%. Of the 120 newly hatched, Ist instar larvae reared at 25°, 77 survived to pupation
for a survival rate of 64%. Of these, 53 (68%) eclosed as viable adults, giving an egg-
adult survival rate of about 15%. These values suggest that the egg is probably the most
vulnerable life stage. The principal source of mortality in the pupal stage appeared to
result from fungal infection, but a number of adults eclosed with marked elytral
deformities and were presumed non-viable. This may have been an artifact of the
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 47
constant temperature regime under which the insects were reared. Such an effect of
constant temperatures on development has been noted for other Chrysomelid beetles.
Mason & Lawson (1980) were unable to rear any normal adults of the american aspen
beetle, Gonioctena americana (Schaeffer), under constant temperature conditions,
whereas development was normal in oscillating temperature.
A total of 35 larvae pupated in the larval consumption assay. The mean consumption
per larva surviving to pupation was estimated to be 27.6 mg dry weight of leaf. Larvae
feed selectively on the undersides of leaves, leaving behind several layers of cells on the
upper leaf surface that subsequently senesce. Therefore the amount of leaf actually
consumed underestimates foliar damage by as much as 50%.
Callow adults eclosing in the laboratory behaved very differently from the overwin-
tered adults collected in the spring. They responded photonegatively and tended to
aggregate underneath the filter paper in the dishes, remaining relatively inactive,
emerging only at night to consume small amounts of the leaves provided. They were also
observed to consume portions of alder leaves, Alnus rubra, when these were made
available together with fireweed. Larvae would not accept alder, even in a no-choice
situation. On several occasions, pairs in copula were observed, and a few eggs were
eventually deposited on the leaves and filter paper. This was apparently less ovipositional
activity than that observed by Dirks-Edmunds (1965) in Ist-generation adults reared in
Oregon. This author concluded that two complete generations may occur in that region.
It is possible, nevertheless, that a partial second period of oviposition may occur in B.C.
under suitable conditions.
Of six overwintered adults collected on May 22, 1987, near Shawnigan Lake on
Vancouver Island, two were parasitized and yielded pupae that were incubated until
eclosion. The emerging parasite adults were identified! as males of the genus Medina
Robineau-Desvoidy (tribe Blodeliini), probably M. barbarta, although identification to
species could not be made with certainty.
1. J.E. O’Hara, Dept. of Entomology, Univ. of Alberta, 255 Earth Sciences Building, Edmonton, Alberta,
T6G 2E3.
ACKNOWLEDGEMENTS
Thanks are due to Dr. M. Mackauer for supervising this research and providing advice on
sampling techniques and to Dr. J. Borden for his editorial advice. This research was
sponsored, in part, by G.R.E.A.T. Award #73 (GC-8) from the Science Council of
British Columbia and by the British Columbia Honey Producers Association.
REFERENCES
Atkins, M.D. (1964). Altica tombacina Mannerheim (Coleoptera: Chrysomelidae); a serious pest of fireweed.
Proc. Ent. Soc. B.C. 61:44—45.
Dirks-Edmunds, J.C. (1965). Habits and life history of the bronze flea beetle, Altica tombacina Mannerheim
(Coleoptera: Chrysomelidae). Northw. Sci. 39(4):148-158.
Mason, M.L. & EA. Lawson (1980). Laboratory rearing of the American aspen beetle (Coleoptera:
Chrysomelidae: Gonioctena americana [Schaeffer] ). J. Kan. Ent. Soc. 53(2):421-422.
Michaud, J.P. (1989). Nectar accumulation in flowers of fireweed, Epilobium angustifolium L. (Onagraceae), in
response to simulated defoliation. J. Apic. Res. 28(4):181-186.
Michaud, J.P. (1990). Biomass allocation in fireweed, Epilobium angustifolium L., (Onagraceae), in response to
simulated defoliation. Bot. Gaz. (in press).
Phillips, W.M. (1977). Observations on the biology and ecology of the chrysomelid genus Haltica Geoff. in
Britain. Ecol. Ent. 2:205-216.
Port, C.M. & C.T. Guile (1986). Outbreaks of flea beetles, Altica spp., on heather and other flowering plants.
Plant Path. 35:575-577.
Woods, W.C. (1918). Biology of the Maine species of Altica. Maine Agr. Exp. St. Bull. 273:149-205.
48
May 12
COW ON
- OOF KH NHK KY
Orrr ONOCOC CO
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
APPENDIX
Numbers of A. tombacina Adults — 1988
May 24 June 3 June 15 June 27 July 10 July 22
1 0 0 1 0 0
1 0 0 Z 1 0
0 0 0 0 9 0
0 0 0 9 0 0
0 0 0 3 1 0
7 0 4 0 1 0
5 0 1 1 0 0
110 0 1 0 0 1
159 0 0 1 2 0
11 0 4 0 0 2
11 0 0 1 0 0
16 0 2 3 1 0
0 0 6 0 3 0
3 0 5 1 4 0
1 0 3 3 3 0
0 0 1 0 0 0
1 0 3 1 0 0
0 0 5 0 2 0
0 0 0 1 z 0
0 0 0 2 0 0
0 0 2 13 1 0
0 0 0 0 1 0
0 0 2 1 0 0
0 0 6 0 0 0
0 0 l 2 0 0
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
May 12
NO ONS
May 24 June 3 June 15 June 27
5 9 0 20
1 ps 0 12
82 47 NB) 30
9 19 26 24
4 10 17 5
215 300 3287 926
163 17, 936 684
819 1882 3565 626
746 2704 4791 1300
176 421 883 904
387 1560 2066 679
63 266 174 362
41 179 324 670
89 232 847 2932
22 88 173 675
15 38 127 388
106 115 318 551
69 134 276 808
220 180 208 586
40 63 122 567
pil 50 154 830
39 79 97 285
65 44 47 189
18 86 358 671
77 49 244 236
Numbers of A. tombacina Larvae — 1988
June 27 July 10 July 22
0 0 3
0 0 0
3 1 0
0 0 0
0 0 0
6 3 1
2) 21 0
460 46 5
phe 121 2
121 37 0
131 112 1
0 0 0
0 34 23
33 300 212
0 80 14
0 0 1
13 0 1
0 6 7
5 14 7
0 8 0
0 8 0
0 8 3
0 4 5
0 0 0
0 0 12
Numbers of A. tombacina Eggs—1988
July 10
11
1
24
Aug 3
aera iia) T=)
oooocnocnooco
coooocoooo°c*oeoo
49
July 22
oooc]e
—
ounoooo°ceowo-
Mooonrnoncncoceo
50 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
A rapid method of sampling
for aphids on strawberries
B.D. FRAZER and R.R. McGREGOR
AGRICULTURE CANADA RESEARCH STATION
6660 N.W. MARINE DRIVE
VANCOUVER, B.C. CANADA V6T 1X2
ABSTRACT
A rapid system of sampling for strawberry aphids, Chaetosiphon fragaefolii (Cockerell)
was developed for use by pest management scouts. Regression equations relating mean
numbers of aphids/leaf, variances of those means and the proportion of unifested leaves
(Po) were developed from samples of aphids from single leaves. Using the equations,
mean aphid density per leaf and standard errors can be estimated from P, and the sample
size. The accuracy of the estimations were tested on data from 155 samples from
commercial strawberry fields sampled by a professional pest management company.
Means estimated from Py were sufficiently accurate for the intended purpose and only 2
hours were required to sample 300 leaves compared to 16 hours when all aphids on all
leaves were counted from only 80 leaves. An electronic recorder was programmed to
prompt an IPM scout for data entry, allow correction of errors and permit sampling from
different subplots within a field.
INTRODUCTION
Sixteen species of aphids have been recorded on species of Fragaria worldwide
(Blackman and Eastop 1984). All but two species have been found in south-western
British Columbia, but only nine have been collected from strawberries (Forbes and Chan
1987). The strawberry aphid (Chaetosiphon fragaefolii [Cockerell]), of North American
origin, is present in most commercial strawberry growing areas of the world. Aphids of
all species cause infrequent and limited direct damage to strawberries, but plant viruses
transmitted by aphids are responsible for major economic losses and increased costs of
production in B.C. and most other areas of commercial strawberry production (Aerts,
1973).
C. fragaefolii is the most numerous and efficient vector of viruses transmissable to
strawberries by aphids (Mellor and Forbes, 1960; Frazier and Converse 1980). Virus
infection results in a progressive decline in vigor and yield (Martin and Converse, 1977)
that necessitates replanting. In California, yields are commercially acceptable for only
15 to 18 months (Trumble et al., 1983). In B.C., replanting is required every 3 to 5 years
depending upon the degree of isolation between fields.
Strategies to protect strawberries from virus infection vary regionally depending upon
the aphid fauna, virus complex and adequacy of certification programs to produce virus-
free plants. Insecticide applications can reduce aphid numbers and retard the spread of
viruses, but even when aphid numbers are very low, plants can become infected by one or
more viruses within their first year of field exposure (Converse and Aliniazee, 1987).
Breeding strawberries for tolerance to viruses and controlling aphids reduces damage
and virus spread thereby prolonging plant vigour (Barritt and Daubeny, 1982). Even well-
managed commercial fields of tolerant cultivars are replanted regularly because of the
deleterious accumulated effects of viruses.
Modern pest management relies upon the results of sampling to make decisions about
pest control. An effective sampling program must produce reliable results in a short
time. Collecting 80 leaves from a field, removing and counting aphids in the laboratory
can take as long as 16 hours for one person to do. Aphids must be removed to avoid
counting them more than once. This is an economically unacceptable amount of effort for
a grower or pest management scout.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 5a
Progress has been made (Nachman, 1984; Raworth and Merkens, 1987) in estimating
the density of mites on strawberries from the proportion of pest habitats that are not
infested (P,)). Pp of strawberry aphids on immature leaves was correlated with the total
‘population on individual plants (Trumble et al., 1983).
This paper describes the development and testing of a method of sampling for C.
fragaefolii based on Po.
METHODS AND MATERIALS
Development of Sampling Program
A research plot (12 matted rows, each one meter apart and 30 m long) of Totem
strawberries planted 1 May 1986, was sampled at about weekly intervals when picking,
cultivation and irrigation permitted during 1987 and 1988 from 1 May until first frost in
November. No insecticides were used on the plot but one application of simazine at 2.25
(ai) kg/ha for weed control was applied one month before sampling began each year.
Sampling consisted of collecting one new leaf from each of 80 plant crowns selected
arbitrarily from sites evenly spaced throughout the plot. Selected leaves had elongate
petioles with lamina that had not unfurled, the leaves preferred by C. fragaefolii (Dicker,
1952). Leaves were placed singly in plastic bags kept on crushed ice in a cooler. The
number and instar of aphids on each leaf were counted and recorded after being removed
from each leaf under a microscope ( X 30). The mean number of aphids per sample (M)
and its variance (V) were calculated and In(V) was regressed against In(M) following
Taylor (1961). The proportion of leaves that had no aphids (P,) were calculated for each
sample, transformed to In(— In[P,]) and regressed against M (Nachman, 1984).
Evaluation
A private company (Monagro Consultants Inc.) sampled 27 commercial strawberry
fields during 1987 to advise growers of aphid densities and give recommendations for the
control of aphids. Leaves were examined in the field with a x 10 magnifier mounted on a
headband. The data were made available to us and consisted of 220 records of mean
aphids per leaf (M), the sample size (N) and Py. We were not given the age, cultivar,
location or history of pesticide applications of the sampled fields. Samples from less than
40 leaves were discarded, leaving 155 samples for analysis.
Statistical analyses were done with SPSS-PC + (SPSS Inc.) on a CompaQ Deskpro
286 microcomputer. The level of significance used for hypothesis testing was 5%.
RESULTS
Linear regressions between In(M) and In(V) (Taylor, 1961) (Fig. 1A) and between In(M)
and In(— In[po]) (Fig. 1B) were developed with data from the research plots.
Eq. 1. InV = 1.285 + 1.206InM R2 =0.93 df = 31
Eq. 2. InM = 0.964 + 1.0431n(—In[po]) r2 = 0.97 df = 31
Evaluation
A linear relationship (Fig. 1B) between In(M) and In( — In[p0] ) was calculated for the
data from the commercial fields. The slope and intercept of the line were not significantly
different from those of the relationship from the research plots (Fig. 1B). The data from
the research plots and commercial fields were combined and the relationship between
In(M) and In( —1n[P)]) recalculated.
Eq. 3 InM = 0.964 + 1.043(1n(— 1nP,)) r2 = 0.87 df = 199
A computer program based on a FORTRAN-77 program (Raworth and Merkens, 1987)
was written in Turbo Pascal 4.0 (Borland International, Scotts Valley, California)
(program available on request). For various levels of P, estimated from sampling, the
program calculates, using equations | and 3, M and the standard error of M that results
By J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
VARIANCE
1
0.5 1 3 ) 9 13
MEAN
Fig. 1A. Relationship between the mean and variance in samples of Chaetosiphon fragaefolii from
leaves in a research planting of strawberries.
when Py is estimated from various numbers of single leaves (Table 1). If a sample of 200
leaves were taken and Py, was equal to 0.6, the mean level of infestation would be 1.47
aphids per leaf with a standard error of +0.22 (15% of 1.47, Table 1). The computer
program is easily modified to print tables with gradations in P, and standard errors as fine
as desired.
A field to be sampled was measured with the aid of a Rolatape (Rolatape Corporation,
Spokane, Washington) measuring wheel and the number and spacing of rows deter-
mined. The field was then drawn to scale and a plan for sampling the field was developed.
In 1989 our interest was primarily in evaluation the utility and efficiency of the Po
method of sampling and in determining if the edges of fields should be sampled
separately from the centre of fields. While 20 commercial strawberry fields were
sampled, each in a manner to answer specific research questions, results from only one
are presented. That field was a 3.6 ha rectangle of 2 year old Totem strawberries. It was
sampled 6 times during the growing season when agricultural operations were permitted.
Sampling was done separately from each edge of the field and from two central areas
separated by aroad. A sample was taken approximately every 7m as the sampler walked
through the field. One sample of the field required 2 hours to complete. Three hundred
leaves were inspected from each field, 50 from each edge and each central strip of the
field.
A model 600 Polycorder (Omnidata International, Logan, Utah) was programmed to
prompt the operator for input and permit corrections to entered data. The instrument
displayed a code number representing the particular area of the field being sampled and
the number of leaves that had been sampled. The Polycorder stored the area code and
each sample outcome (leaf with or without aphids). We programmed the instrument to
request, on a relative subjective scale, the temperature, leaf wetness, cloud cover and
wind speed.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 53
MEAN
In (-In(Po))
Fig. 1B. Relationship between mean number of Chaetosiphon fragaefolii per leaf and the propor-
tion of uninfested leaves (P,) in samples collected from research ( + ) and commercial (¢) plantings
of strawberries.
The data from the Polycorder were downloaded to a microcomputer for estimation of
P, and the corresponding M. The program for the Polycorder is available from the
authors. The mean density of aphids in the 6 sampled areas of the field (Table 2) was
similar for most of the year except on 8 July when the edges had only one-half the density
of aphids on the central subplots.
DISCUSSION
Sampling strawberry aphids on a presence or absence basis provides estimates of the
mean sufficiently accurate for pest management purposes. When most leaves have aphids
(Pp = 0.05), aphid density exceeds 9/leaf with a variance of 53. At that level of
infestation and dispersion, very heavily infested leaves are evident in every meter of row.
When densities are very low (high P,), large sample sizes would be needed to determine
a mean level of infestation with accuracy. However, at low density, great accuracy is not
required because further reduction of the density would not be contemplated. If the
initial sample size is too low for the level of precision required, more samples can be
taken before the scout leaves the field. The grower can be immediately informed of the
results and future sampling scheduled at that time. The Polycorder and the programs
developed to operate it, while not essential, greatly simplify recording and help the scout
to be correctly oriented in large fields and to count the number of samples made.
ACKNOWLEDGEMENTS
We thank Victor Luk and Tom Grieve for technical assistance and discussions; Ward
Strong for providing the data of Monagro Consulting Company; Wes MacDiarmid for
graphics and H. Frazer for editing.
54 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
REFERENCES
Aerts, J. 1973. Effects of a single virus and a virus complex on the yield of 8 strawberry varieties. Med. Facul.
Land. Rijks. Gent. 38:1631-1645.
Barritt, B.H., and H.A. Daubeny. 1982. Inheritance of virus tolerance in strawberry Fragaria ananassa. J.
Amer. Soc. Hort. Sci. 107:278—282.
Converse, R.H., and M.T. Aliniazee. 1987. The reduction in incidence of aphid-borne strawberry viruses in
the field by use of pyrethroid insecticides. Phytopathology 77:1762.
Dicker, G.H.L. 1952. Studies in population fluctuations of the strawberry aphid, Pentatrichopus fragaefolii
(Cock.). 1. Enemies of the strawberry aphid. Ann. Rep. East Malling Res. Sta. 1951. 39:166-168.
Forbes, A.R. and C.K. Chan. 1987. The aphids (Homoptera: Aphididae) of British Columbia 17. A revised
host plant catalogue. J. Entomol. Soc. Brit. Col. 84:72-100.
Frazier, N.W., and R.H. Converse. 1980. Strawberry veinbanding virus. CMI/AAB Descriptions of Plant
Viruses 219.
Martin, L.W., and R.H. Converse. 1977. Influence of recent and chronic virus infections on strawberry growth
and yield. Phytopathology 67:573-575.
Mellor, EC., and A.R. Forbes. 1960. Studies of virus diseases of strawberry in British Columbia. III.
Transmission of strawberry viruses by aphids. Can. J. Bot. 38:343-353.
Nachman, G. 1984. Estimates of mean population density and spatial distribution of Tetranychus urticae
(Acarina: Tetranychidae) and Phytoseiulus persimilis (Acarina: Phytoseiidae) based upon the proportion of
empty sampling units. J. Appl. Ecol. 21:903-913.
Raworth, D.A., and M. Merkens. 1987. Sampling the twospotted spider mite Tetranychus urticae (Acari:
Tetranychidae), on commercial strawberries. J. Entomol. Soc. Brit. Col. 84:17-19.
Taylor, L.R. 1961. Aggregation, variance and the mean. Nature 189:732-735.
Trumble, J.T., E.R. Oatman, and V. Voth. 1983. Development and estimation of aphid populations infesting
annual winter plantings of strawberries in California. J. Econ. Entomol. 76:496-501.
Table 1
Numbers of strawberry leaves, mean numbers of Chaetosiphon fragaefolii per leaf and standard errors
resulting from observed proportions of uninfested leaves (P)). Standard errors are expressed as percentages
of means. An asterisk denotes sample sizes in excess of 10,000 leaves.
Po Mean Number of Leaves at Each Standard Error
5% 10% 15% 20% 25% 30% 35% 40% 45% 50%
0.05 9°31 x 482 162 87 DS) 39 30 23 19 16
0.10' 7,708 ‘ 360 131 71 46 33 2D 19 16 13
0.15 5.78 * 322 122 67 44 31 24 19 15 13
0.20 4.87 “i 308 121 67 44 31 24 19 15 13
0.257. 417 A815 306 123 69 45 32 24 19 16 13
0.30 3.60 4590 311 Pe | oA 47 33 25 20 16 14
0.35 3:12: 53553 322 133 ie) 49 35 27 21 17 15
0:40 0.2.78 ¢Si01 337 141 80 53 38 29 23 19 16
0.45 2.34 2907 359 152 86 ay 41 31 25 20 17
0.50) 2:02: 2871 387 165 94 62 44 34 27 22 18
0.55 1732962 423 181 103 68 49 eM) 30 24 20
0.60 147i St9t 470 202 Ps 76 25) 42 33 27 23
0.65 1.23 3609 534 229 131 86 62 47 37 31 26
0.70 1.01 4347 622 266 152 100 72 55 43 36 30
0.75 0.81 5764 qo 319 182 120 86 65 52 42 36
0.80 0.62 9167 957 399 226 149 107 81 64 39 44
0.85 0.45 : 1332 538 302 197, 141 107 85 69 58
0.90 0.28 - 2241 829 456 295 210 159 126 103 86
0.95 0.13 sy 6201 1817 943 596 419 315 248 201 168
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 55
Table 2
Mean number of Chaetosiphon fragaefolii per strawberry leaf in six areas of a field. An asterisk indicates
when means on the perimeter of field were significantly different from those of the central areas.
Area of Field
Perimeter Center Total
Julian
Day Date West North East South West East
125 May 5 0.0 0.05 0.0 0.0 0.0 0.0 0.01
151 May 31 0.16 0.10 0.16 0.10 0.16 0.16 0.14
156 June 6 0.05 0.22 0.16 0.05 0.34 0:22 0.17
189 July 8 2.50 2.10 2.10 1.40 0.54 0.50 1.42%
198 July 17 1.34 1.16 0.91 0.75 0.99 1.64 Lei
237 Aug 26 O79 1.70 1.44 0.61 ys) 1.09 1 sh2
Toxicity of foliar residues of phosmet to the apple maggot,
Rhagoletis pomonella (Diptera: Tephritidae)!
A.B. MOHAMMAD and M.T. ALINIAZEE
DEPARTMENT OF ENTOMOLOGY
OREGON STATE UNIVERSITY
CORVALLIS, GREGON 97331
ABSTRACT
Mortality of apple maggot (AM), Rhagoletis pomonella (Walsh), was determined in the
laboratory on spray deposits of phosmet (Imidan®) applied to apple foliage and fruit at
rates of 0.6 and 1.2 g active ingredient (AI)/liter (0.5 and 1 pound [AI]/100 gallons).
Mortality of AM adults was 100% with both rates until 16 days post-treatment.
Thereafter, mortality decreased inversely with time. Probit analysis revealed insecticide
residual toxicity of 24 days for 95% mortality (ET,;) for both rates, and 51 and 55 days,
respectively, for 50% mortality (ET<5,) at 0.6 and 1.2 g (AlI)/liter. The intercepts and
Slopes of probit regression were not significantly different for the two rates tested,
indicating little difference between their persistence and efficacy against AM adults.
INTRODUCTION
The apple maggot (AM), Rhagoletis pomonella (Walsh), was first reported in the western
United States near Portland, Oregon (AliNiazee and Penrose, 1981). It is now well
established in six western states including Oregon, Washington, California, Idaho,
Utah, and Colorado (AliNiazee and Brunner, 1986). Most AM infestations in the western
United States are associated with abandoned and unsprayed apple trees and hawthorn
species, both the native Crataegus douglasii Lindley and the introduced ornamental C.
monogyna Jacquin. Isolated infestations of prunes in the Willamette Valley of Oregon
(AliNiazee, 1985) and of cherries in Utah (Jorgensen et al. 1986) have also been noticed.
The only commercial apple-growing area infested with AM in the western United States
is near Salem, Oregon (AliNiazee, 1988).
Therefore, in Oregon and Washington, the primary objective of AM control and
localized eradication programs is to kill all AM females that immigrate into commercial
orchards from surrounding natural habitats before oviposition occurs. Consequently,
protective application of insecticides on a regular basis against immigrating AM females
is the key to successful management of AM in commercial orchards of the Pacific
Northwest (AliNiazee, 1988).
56 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Azinphosmethyl and phosmet are the two most commonly used insecticides against
AM in eastern North America (Reissig, 1988) and phosmet is extensively used in the
west also (AliNiazee, 1988). The AM eradication program pursued in northern Califor-
nia for the past four years, was exclusively dependent on the use of phosment (Dowell,
1988). Bancroft et al. (1974) evaluated the toxicity of about 25 insecticides against AM
adults in the laboratory by topical applications and concluded that phosmet was as toxic
to AM adults as azinphosmethyl. Unlike azinphosmethyl, which has been tested
extensively against AM, both in the laboratory (Bancroft et al. 1974; Reissig et al. 1980,
1983) and in the field (Pree et al. 1976; Reissig et al. 1978; Weires and Alm, 1981)
relatively little experimental data are available on the toxicity and persistence of residue
deposits of phosmet against AM adults in apple orchards. A residual toxicity of two to
three weeks is generally expected but no experimental data are available to support this
conclusion. Here, we report the residual toxicity against AM adults of two rates of
phosmet applied in the field on apple foliage and fruit.
1. Oregon Agricultural Experiment Station Technical Paper No. 8900.
MATERIALS AND METHODS
Phosmet (Imidan 50% wettable powder [WP], Stauffer Chemical Company, Westport,
CT) was applied at rates of 0.6 and 1.2 g (AI)/liter (0.5 and 1 pound [AI]/100 gallons) on
young ‘Red Delicious’ apple trees (1-1.5meters high). The application was made to the
point of drip with a backpack sprayer, in the first week of August 1987 at the Oregon State
University Entomology Research Farm, Corvallis, OR. Each tree had approximately 50
fruit at the time of treatment. Four trees were treated with each rate of phosmet.
Samples of treated apples and leaves were collected in plastic bags without touching
the treated surfaces at 24 h after treatment and at 4-day intervals until 56—60 days post-
treatment. If adequate numbers of AM adults were not available for the tests, the
sampling date was skipped and the treated apples and leaves were collected at the next
consecutive sampling date.
Test insects were obtained from a continuous non-diapausing laboratory colony
(Mohammad and AliNiazee 1989) maintained at a temperature of 25 + 1°C, 70 + 5%
RH, and in constant light. The AM adults were provided with a food mixture of yeast
hydrolysate enzymatic (United States Biochemical Corporation, Cleveland, OH) and
honey, mixed in a ratio of 1:4. Other rearing procedures were similar to those described
by Kamasaki et al. (1972). The colony had been reared for 4-5 generations until these
bioassays. Five to 10-day-old AM adults were used in these tests.
Each post-treatment laboratory test was replicated four times. Ten AM adults (5 males
and 5 females) were tested in each replication. Two additional replications with
unsprayed apples and foliage were also included for assessing the natural mortality of
AM flies. Modified translucent plastic canisters (Rubbermaid Servin’ Saver 12. x 13.5
cm diameter) were used in an inverted position to expose each batch of AM flies to the
treated apples and foliages, as described by Mohammad and AliNiazee, (1989). One
treated apple and 10-12 treated leaves were placed on a paper towel and a modified
canister was inverted, so that the apple and the foliage were in the center of the canister
without touching the sides. Provisions were made for aeration, water, and food for the
AM flies in these canisters. The tests were conducted at 25 + 1°C ina walk-in controlled
environment chamber under fluorescent lights with a photoperiod of 16:8 (L:D). The
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 D7
Table 1
Mortality of apple maggot (AM) adults in the laboratory on residue deposits of phosmet on apple foliage
and fruit collected at different intervals after spray applications.
Days after spray applications AM mortality (%)!
Field rate of phosmet (g [AI]/liter)
0.6 12
4,8, 12, 16 100 100
20 100 94.6
24 94.6 94.6
28 89.1 94.6
32 83.7 iy)
36 Tou 89.1
40 - 83.7
44 133 =
48 ~ iat
52 45.7 —
56 ~ 0?
60 2A -
1. Mortality corrected by Abbott’s formula (Abbott, 1925).
2. Excluded from probit analysis.
Natural mortality of AM flies on unsprayed foliage was 8% (n = 300).
No. of AM flies used in each test = 40 (20 males & 20 females). Mortality counts were made after 48 h
exposure.
numbers of live and dead flies were recorded after 48 hours. Flies which were unable to
walk were considered dead. The mortality counts were corrected by Abbott’s formula
(Abbott, 1925) and the data were analyzed by probit analysis (Russell et al. 1977) for
estimation of time to 95% and 50% mortality (ET); and ET.,) (Pree et al. 1976).
RESULTS AND DISCUSSION
Residues of phosmet caused 100% mortality for 16 days at both rates (Table 1); thereafter,
mortality declines inversely with time. The deposits of phosmet caused 250% AM
mortality until 48 days post-treatment at both rates, thus suggesting a slow rate of
degradation and loss of efficacy. Residual efficacy declined rapidly at 56 and 60 days
post-treatment and the insecticide was ineffective after 60 days. The average tempera-
tures in the field for August, September, and October 1987 were 19.9, 17.1, and 14.1°C,
respectively; the precipitation in Corvallis during these months was 0.43, 0.13, and 0.68
cm, respectively.
Results of probit analysis indicated that for both rates of phosmet, the estimated time
to 95% mortality (ET,,) of AM flies from residue deposits was 24.1 days (95% CL =
21.1-26.5), and 52.8 days (95% CL = 48.0-60.9) for 50% mortality (ET<,.). The slopes
and intercepts of the probit regressions for both dosages were similar (x? [likelihood ratio
test for equality of slopes and intercepts] = 0.458; df = 2) and the data for both dosages
of phosmet (0.6 and 1.2 g [AI]/liter) could be represented by acommon slope (— 4.83 +
0.56; n = 960; tratio = — 8.58;) and acommon intercept (8.33 + 0.87; n = 960; tratio
= 9.53). The probit analysis therefore, indicated little differences between efficacies of
residue deposits of the two rates for a period of 48-52 days post-treatment.
Bancroft et al. (1974) suggested that phosmet and azinphosmethyl] were equally toxic |
to AM adults in laboratory, and Pree et al. (1976) reported that foliar residues of
dimethoate and azinphosmethyl] caused 50% mortality (ET;, levels) for 28-30 and 18-20
days, respectively. Data presented here (ET,, = 24.1 days and ET;, = 52.8 days) show
that phosmet was much more persistent in Oregon than either of the two insecticides
tested in New York and Ontario.
58 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Reissig et al. (1983) determined mortality and oviposition behavior of gravid AM
females after various exposure periods on different concentrations of surface residues of
azinphosmethyl and found oviposition inhibition in addition to adult mortality. Even at
sublethal dosages, the inhibition of oviposition was noticeable. Most AM adults used in
our study were 5-10 days old and had not yet begun oviposition, thus oviposition
inhibition effects of phosmet residues were not studied. It is likely, however, that
phosmet residues may also have similar oviposition deterrent effects in addition to
mortality of AM adults.
ACKNOWLEDGEMENT
This study was funded by the Agricultural Research Foundation of Oregon State
University, Corvallis, and the California Department of Food and Agriculture (grant
#7905), Sacramento.
REFERENCES CITED
Abbott, W.S. 1925. A method of computing the effectiveness of an insecticide. J. Econ. Entomol. 18:265—267.
AliNiazee, M.T. 1985. Apple maggot in Oregon. Oregon Horticultural Soc. Proc. 76:80-82.
AliNiazee, M.T. 1988. Apple maggot management in the western United States. pp. 73-81. In: M.T. AliNiazee
(ed.), Ecology and Management of Economically Important Fruit Flies. Agricultural Experiment Station,
Oregon State University Special Report 830, Corvallis.
AliNiazee, M.T. and J.E Brunner. 1986. Apple maggot in the western United States: A review of its
establishment and current approaches to management. J. Entomol. Soc. Brit. Columbia 83:49-53.
AliNiazee, M.T. and R.L. Penrose. 1981. Apple maggot in Oregon: A possible new threat to the Northwest
apple industry. Bull. Entomol. Soc. Am. 27:245-246.
Bancroft, R.P, D.J. Pree, and D.P. Toews. 1974. Comparative toxicities of some insecticides to the apple
maggot. J. Econ. Entomol. 67:481—483.
Dowell, R.V. 1988. Exclusion, detection, and eradication of exotic fruit flies in California. pp. 98-112. In:
M.T. AliNiazee (ed.), Ecology and Management of Economically Important Fruit Flies. Agricultural
Experiment Station, Oregon State University Special Report 830, Corvallis.
Jorgensen, C.D., D.B. Allen, and R.L. Westcott. 1986. Apple maggot (Rhagoletis pomonella) adaptation for
cherries in Utah. Great Basin Nat. 46:173-174.
Kamasaki, H., H.S. Myers, and D.F Ralston. 1972. Mass rearing the apple maggot. J. Econ. Entomol.
65:1292-1295.
Mohammad, A.B. and M.T. AliNiazee. 1989. Malathion bait sprays for control of apple maggot (Diptera:
Tephritidae). J. Econ. Entomol. 82:1716—1721.
Pree, D.J., K.P. Butler, E.R. Kimball, and D.K.R. Stewart. 1976. Persistence of foliar residues of dimethoate
and azinphosmethyl and their toxicity to the apple maggot. J. Econ. Entomol. 69:473-478.
Reissig, W.H. 1988. Management of apple maggot in the eastern United States. pp. 56-72. In: M.T. AliNiazee
(ed.), Ecology and Management of Economically Important Fruit Flies. Agricultural Experiment Station,
Oregon State University Special Report 830, Corvallis.
Reissig, W.H., D.H. Dunham, and H.E. Hebding. 1978. Apple, seasonal insecticide test, 1977. Insecticide
Acaricide Tests 3:33-34.
Reissig, W.H., B.H. Stanley, M.E. Valla, R.C. Seem, and J.B. Bourke. 1983. Effects of surface residues of
azinphosmethyl on apple maggot behavior, oviposition, and mortality. Environ. Entomol. 12:815-822.
Reissig, W.H., R.W. Weires, and D.M. Soderlund. 1980. Laboratory and field tests of insecticides against the
apple maggot. J. Econ. Entomol. 73:752-754.
Russell, R.M., J.L. Robertson, and N.E. Savin. 1977. POLO: a new computer program for probit analysis.
Bull. Entomol. Soc. Am. 23:209-213.
Weires, R.W. and S.R. Alm. 1981. Apple, insect control, Hudson Valley, Highland, New York, 1980. Insecti-
cide Acaricide Tests 6:27-28.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 59
Predators associated with the twospotted spider mite,
Tetranychus urticae, on strawberry at Abbotsford, B.C.,
and development of non-chemical mite control
D.A. RAWORTH
AGRICULTURE CANADA RESEARCH STATION
6660 N.W. MARINE DRIVE
VANCOUVER, B.C. CANADA V6T 1X2
ABSTRACT
Populations of the twospotted spider mite, Tetranychus urticae Koch on strawberry were sampled from
1983-86. The predaceous mite, Amblyseius fallacis (Garman), was predominant. Active adults were
observed in February and November, earlier in the spring and later in the autumn than any other predator.
Amblyseius fallacis, cecidomyiid flies of Aphidoletes sp. and the ladybird beetle, Stethorus punctum picipes
Csy., all responded numerically to introductions of the twospotted mite but A. fallacis responded to the
greatest degree. The rate of increase of A. fallacis on a log, scale was 1.0335 + 0.0621 per 100 degree-days
above 4C (DD,) in the spring and summer, and 0.5481 + 0.0845 per 100 DD, in late summer, about 2.1 x
and 1.6 per week on an arithmetic scale. Slide dip tests showed that populations of A. fallacis in the
Lower Fraser Valley were resistant to the chemical compounds cyhexatin, endosulfan and malathion,
partially resistant to diazinon and very susceptible to carbofuran, demeton, dicofol and dimethoate.
Biocontrol of T. urticae is discussed in the context of integration with the chemical control of aphids, and
predator release rates.
INTRODUCTION
The twospotted spider mite, Jetranychus urticae Koch, has long been a sporadic problem
on cultivated strawberry, Fragaria x ananassa Duch., in the Lower Fraser Valley.
Although miticides have been used to regulate this pest, researchers and extension
workers have thought for some time that alternative methods of mite control should be
developed. Work was initiated in 1983 to determine an economic threshold for 7: urticae
on strawberry (Raworth 1986a), to develop simple sampling methods that can be used by
pest managers (Raworth and Merkens 1987), and to develop a management plan for the
pest (Raworth and Strong 1990). To date, however, there has been no satisfactory
alternative method for regulating twospotted mites on strawberry. This paper presents
data about natural predators that have been found on strawberry during the previous
studies and discusses biocontrol strategies.
MATERIALS AND METHODS
Twospotted Mite Introductions and Field Samples.
A 0.54 ha field of ‘Totem’ strawberries was planted at Abbotsford 3-6 May, 1983. The
crowns were 60 cm apart within rows and 120 cm between rows. Runners were allowed to
propagate, forming a ‘matted row.’ The field was sprayed once with diazinon every April
for aphid control and with simazine (Simadex 500 F) each autumn for weed control. No
other pesticides were applied. Tetranychus urticae was mass-reared in the laboratory for
field introductions by splitting one mite-infested leaflet between every eight leaflets of
potted strawberry plants and allowing the populations to increase for 10-14 days at 22°C.
On 19 May, 1983 every second plant in the field was infested with twospotted mites.
Samples of 900 leaflets were collected every 2 weeks and processed with a mite brushing
machine. Unknown mites and insects were saved in 90% EtOH and sent to the Biosys-
tematics Research Centre for identification. In 1984 the field was divided into 16 plots,
each consisting of seven 7-m matted rows. Plots were separated from each other by 10 m
of untreated field. Twospotted mites were introduced into the plots at different rates
during 1984—86 (Table 1). Accurate counts of the twospotted mite and its associated
predators in each plot were made by collecting mature leaflets at random, holding them at
4°C, and examining them later with a 12 X stereomicroscope. The average number of
N
0 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Table 1
Introduction levels of the twospotted spider mite, Tetranychus urticae, and the predatory mite,
Phytoseiulus persimilis, replication, experimental design, and sample sizes per replicate
on each sampling date
Trial Treatment Rate Reps Design? Introduction Sample sizes per rep
(Mite infested Date Mite sample Plant sample
leaflets per plot)! (D/M/Y) No. leaflets No. quadrats
il T. urticae 0:42:126:378 4 RCB 26/4/84 35 7
2: T. urticae 140 16 26/4/85
P. persimilis 0:28:84:168 4 RCB 2/5/85 35 ah
Se T. urticae 0:294 4 R 7/5/86 70 7
4. T. urticae 0:450 2 R 2/7/86 70 a
1. These rates apply only to T. urticae. Rates for P. persimilis are the number of adult predators on P
persimilis-infested leaflets, per plot. Phytoseiulus persimilis eggs and immatures were also introduced on
the leaflets.
2. RCB—Randomized complete block; R—Completely randomized.
mature leaves in 30 cm of row was also determined for each plot by using quadrats (Table
1). Densities of mites and insects were expressed as numbers per row-meter. The sample
data were transformed using natural logarithms and analyzed by ANova, setting sample-
day as a split-plot. Standard errors were calculated from the residual variation used to
test treatment differences. Data were analyzed only for species that consistently
appeared in the samples. An index of total numbers for each species during the season,
“T. urticae-days”’ and “predator-days,” was derived by interpolating the geometric
mean number of each species for each day between samples, and summing the estimates
for the whole sample period.
Resistance of the predatory mite, Amblyseius fallacis (Garman) to Pesticides.
During 1986, 10 commercial fields were sampled for twospotted mites. Amblyseius
fallacis was found in five of the fields between Langley and Agassiz. Collections from
four of these locations were maintained in isolated cultures and tested for resistance to
field rates of eight pesticides (Table 2) that were commonly used to control pests of
strawberry. The slide-dip methodology followed Anonymous (1968) and the modifica-
tion of Croft et al. (1976), but with 10 A. fallacis females per slide rather than 50. The
proportion of females alive 48 h after exposure to a pesticide was transformed by arc-
sine square-root and analyzed by ANova. Duncan’s New Multiple Range Test was used to
separate means.
Table 2
Proportion of adult female Amblyseius fallacis surviving, 48 h after exposure to a pesticide mixed at a
concentration equivalent to the maximum recommended field rate (Anonymous 1986).
Each replicate ‘n’ tested survivorship of 10 females
Pesticide Class! Concentration Proportion n S.E:3 Proportion
(ppm) alive? alive
demeton (Systox SC; 240 g/L) OP 500 0.0 a 12 4.193 0.0
dimethoate (Cygon 480 E) OP 1600 0.0 a 8 S139 0.0
carbofuran (Furadan 480 F) C 1100 2.30a 8 3.835) 0.0016
dicofol (Kelthane EC; 18.5%e.c.) OC 400 1325). 8 5.135 0.054
diazinon (Diazinon 50 EC) OP 900 48.4 b 16 3.631 0.56
endosulfan (Thiodan 4 E) OC 800 66.3 c 16 3.631 0.84
cyhexatin (Plictran 50 W) OT 600 69.3 c 16 3.631 0.88
malathion (Malathion 50 EC) OP 1200 69.9 c 16 3.631 0.88
distilled water 18.3-¢ 28 2.745 0.96
1. C—carbamate; OC — organochlorine; OP— organophosphate; OT — organotin
2. Data transformed by arc-sine square-root. Means followed by different letters are significantly different
(p < 0.01) according to Duncan’s New Multiple Range Test.
. Standard errors given in transformed scale
. Means back-transformed to original scale
WwW
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 61
Table 3
Natural predators collected from ‘Totem’ strawberry leaflets that were infested
with the twospotted spider mite, Tetranychus urticae, at Abbotsford, British Columbia
Predator name Date
ACARI: MESOSTIGMATA
Phytoseiidae Amblyseius andersoni (Chant) 2 Aug. 1983
A. fallacis (Garman) 30 Aug. 1983
A. isuki Chant & Hansell 2 Aug. 1983
A. okanagensis (Chant) 31 May 1985
Typhlodromus pyri Scheuten 2 Aug. 1983
ACARI: PROSTIGMATA
Anystidae Anystis sp. 20 June 1985
Bdellidae Thoribdella nr. simplex 4 July 1984
COLEOPTERA:
Coccinellidae Stethorus punctum picipes Csy. 19 July 1984
DIPTERA:
Cecidomyiidae Aphidoletes sp. 4 July 1984
RESULTS
Twospotted Mite Introductions and Field Samples.
Seven species of predaceous mites and two of predaceous insects were found to occur
naturally (Table 3). The introduction levels of twospotted mites in 1984 resulted in
significantly different population levels of the pest (p < 0.01, Fig.1), the predatory mite,
A. fallacis (p < 0.01, Fig.2), a cecidomyiid fly of Aphidoletes sp. (p < 0.05, Fig.3) anda
ladybird beetle, Stethorus punctum picipes Csy. (p < 0.05, Fig.4). No twospotted mites
or predators were seen in three samples of 60 leaflets collected from the field prior to the
experiment (27 March, 10 and 24 April). Amblyseius fallacis and larvae of Aphidoletes
sp. appeared simultaneously in the mid-June sample. The beetle larvae appeared in the
next sample, but the eggs had been seen in the mid-June sample, indicating predation on
(Number/row—meter) +1
May June July Aug.
1984
Fig 1. Population trends of Tetranychus urticae in 1984 at four introduction levels (high— asterisk;
medium — circle; low — square; control —triangle. See Table 1). Vertical bars indicate + 1 SE of the
geometric mean. The left arrow indicates the introduction of twospotted mites and the right arrow,
the mowing of the field.
62 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
400.0
0030
=
Ps
) 40.0
e
|
2
2) 4 HOO
~~
©
ie 4.0
=
=
Zz
oy 10
0.6
May June July Aug.
1984
Fig. 2. Population trends of Amblyseius fallacis in 1984 at four introduction levels of twospotted
mites (high— asterisk; medium — circle; low — square; control —triangle. See Table 1). Vertical bars
indicate +1 SE of the geometric mean. The left arrow indicates the introduction of twospotted
mites and the right arrow, the mowing of the field.
400.0
te. 100.0
i.
—
) 40.0
=
|
2
2 = 10:0
Do
5
= 4.0
=
SS
Z
ra 1.0
0.6
May June July Aug.
1984
Fig. 3. Population trends of Aphidoletes sp. larvae in 1984 at four introduction levels of twospotted
mites (high — asterisk; medium —circle; low — square; control —triangle. See Table 1). Vertical bars
indicate +1 SE of the geometric mean. The left arrow indicates the introduction of twospotted
mites and the right arrow, the mowing of the field.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 63
400.0
per 00.0
RS
=
o 40.0
&
|
=
oy "4020
~~
©
2 4.0
‘=
Sd
PEA
ae 1.0
0.6
May June July Aug.
1984
Fig. 4. Population trends of larvae of Stethorus punctum picipes in 1984 at four introduction levels
of twospotted mites (high— asterisk; medium —circle; low — square; control —triangle. (See Table
1.) Vertical bars indicate + 1 SEof the geometric mean. The left arrow indicates the introduction of
twospotted mites and the right arrow, the mowing of the field.
Predator—days (1000)
O 200 400 600 800
Prey—days (1000)
Fig. 5. The number of predator-days (Amblyseius fallacis —circle; Aphidoletes sp. larvae — square;
and Stethorus punctum picipes larvae — triangle) as a function of twospotted-mite-days. The overall
within-species regression was statistically significant (p<0.01 r=0.714 8df), and the slopes of the
individual regressions were significantly different (p<0.01; A. fallacis 0.0047; Aphidoletes sp.
0.00075; and S. punctum picipes 0.00071 where +1 SE =0.0005009).
64 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
(Number/row—meter)+1
April May June July
1985
Fig. 6. Population trends of: Tetranychus urticae—asterisk; Amblyseius fallacis—circle; Phy-
toseiulus persimilis—diamond; and Stethorus punctum picipes larvae — triangle, in 1985. Vertical
bars indicate + 1 SE of the geometric mean. The left arrow indicates the introduction of twospotted
mites and the right arrow, the introduction of P. persimilis.
40000.0
__ 10000.0 | |
AU 4000.0
mee
2
~ . 1000.0
= 400.0
=
fe) 100.0
—
Ps 40.0
oO
8 Dey
e 10.0
Ss 4.0
1:6
0.6
April May June July Aug.
1986
Fig. 7. Population trends of: Tetranychus urticae—asterisk; and Amblyseius fallacis—circle, in
1986. Vertical bars indicate +1 SE of the geometric mean. The left arrow indicates the first
introduction of twospotted mites and the right arrow, the second introduction.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 65
twospotted mites by adults. Only A. fallacis was observed in the autumn samples. The
response of A. fallacis in terms of accumulated predator-days at different levels of
twospotted mites was significantly greater than that of the other two species (Fig.5).
Twospotted mites overwintered in the field in 1985, and A. fallacis appeared in the
samples before any other predator (Fig. 6). Analysis of the sample data prior to the
introduction of the pest indicated that there was no carry-over effect of the 1984
treatments with respect to the prey or predator (p > 0.05). Analysis of the sample data
after the introduction of the predator mite, Phytoseiulus persimilis Athias-Henriot,
suggested that there were no detectable effects from its various introduction levels (p >
0.05). The numbers of twospotted mites and associated predators in the 16 plots were
therefore pooled. Population levels of A. fallacis were much higher than those of P.
persimilis and S. punctum picipes (Fig.6). Only one Aphidoletes sp. larva was seen on
560 leaflets on 10 June, and three on 30 June. The presence of eggs of the ladybird beetle
indicated predation on twospotted mites by adult beetles from 20 May to 30 June. Active
A. fallacis were collected in field samples as late as 15 November. Phytoseiulus
persimilis, a tropical species, did not overwinter successfully to the spring of 1986.
In 1986, A. fallacis was collected in a field sample on 16 February. The average
number per row-m in March-April, 17.2 (+5.56, — 4.21) (Fig. 7), was higher than the
number observed in April 1985 (Fig. 6). Introductions of twospotted mites in May and
July failed to produce significantly different population trends relative to control plots
(p>0.05), despite the fact that the release rates were equivalent to those of the medium-
to-high density treatments of 1984 (Table 1). The data for the treatments and controls
were therefore pooled (Fig. 7). Only four S. punctum picipes larvae were observed on 560
leaflets on 2 June, and three were observed on 16 June. However, the presence of eggs of
the ladybird beetle indicated adult predation on the twospotted mites from 22 May to 7
August. One Aphidoletes sp. larva was observed on 16 June. The A. fallacis population
trend followed that of the twospotted mites from April through August.
Amblyseius fallacis was the predominant predator of T: urticae over the 3 years. The
rate of increase of A. fallacis in each treatment in 1984, and in each experiment in 1985—
86 was determined as the slope of the regression of In(mean number per row-m) against
degree-days above 4°C (DD,) (Table 4). Although there was a statistically significant
relationship between the rate of increase of A. fallacis and the average density of
twospotted mites during the time when A. fallacis was increasing in 1984, the data for
1985-86 did not support the relationship. The two lowest rates of increase were observed
during August and September and these were significantly different from the rates
observed during May, June and July (p<0.05). Based on an overall regression, the
average rate of increase of A. fallacis per 100 DD, during spring and early summer was
1.0335 +0.0621, while that during late summer and early autumn was 0.5481 + 0.0845.
These rates were equivalent to a population increase of 2.1 and 1.6 per week
[eCbxtime/100)]: where ‘b’ is the slope of the regression line and ‘time’ is DD, per week
(about 70 DD, per week from May to July and 85 from August to mid-September).
Resistance of the predatory mite, A. fallacis to Pesticides.
There were no differences in pesticide resistance with respect to the origin of A. fallacis
(p > 0.05), but there were differences in resistance to the different pesticides (Table 2).
Carbofuran, demeton, dicofol and dimethoate were very toxic, whereas cyhexatin,
endosulfan, and malathion had little effect. Diazinon was intermediate. There did not
appear to be any cross-resistance between pesticides within similar chemical groups.
66 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Table 4
Rates of increase of Amblyseius fallacis, calculated as the slope of the regression of In(mean per row-m)
against degree-days above 4C (DD,). The geometric mean density of twospotted mites
during the period of A. fallacis increase was also determined
Year Months Treatment Rate (+ SE) Density of
per 100 DD, twospotted mites per
row-m
1984 July - Sept. Control 0.5299 0.1104 535
June - July Low 0.7822 0.2175 3861
June - July Medium 1.1128 0.2175 11555
June - July High 1.2597 0.2175 15589
1985 May - June Pooled 1.0012 0.1967 376
1986 May Pooled 0.9897 0.3780 373
July - Aug. Pooled 0.6048 0.1952 625
DISCUSSION
Several predator species were associated with twospotted mites on strawberry but one,
A. fallacis, has a number of qualities that make it potentially useful as a biological
control agent: it successfully overwinters; it may be found associated with its prey from
early spring until late autumn; it responds numerically to population increases of
twospotted mites, with a rate of increase equivalent to that of the prey in commercial
fields (Raworth and Strong 1990); it is resistant to a number of pesticides; and it can be
reared in the laboratory throughout the year. However, the data presented do not indicate
how effective A. fallacis was at regulating twospotted mites because there were no
controls in which predators were excluded. Experimental releases of mass-reared A.
fallacis are needed. A basic problem with releasing predaceous mites to control 7.
urticae is that the predators are usually exposed to pesticides applied to control aphids.
Aphids vector virus diseases that substantially reduce yields (Mellor and Krczal 1987)
and are of great concern to growers. In the past, endosulfan, diazinon and malathion
were used to control aphids. Amblyseius fallacis has some resistance to these compounds
(Table 2), but recently, many growers have preferred to control aphids with a systemic
such as demeton, which is highly toxic to A. fallacis. Integration of A. fallacis releases
into the current cultural system may be possible by artificially selecting for resistance to
specific pesticides (Hoy 1982). Alternatively, because aphid numbers increase most in
the spring (Shanks 1965), systemic sprays could be used before harvest, and a spray-free
period could be established after harvest to provide time for increase in the numbers of
introduced predators. Given the activity of A. fallacis late in the autumn and early in the
spring, its introduction would maximize the effective length of the spray-free ‘window.’
When it is necessary to spray for aphids in the autumn, one of the three pesticides that are
not harmful to A. fallacis could be used.
Raworth and Strong (1990) developed and tested a management plan for twospotted
mites. Sampling is recommended at intervals of 1-3 weeks when mite density is below
five per leaflet and, above that level, sprays are recommended depending on the rate of
population increase. However, neither the plan nor the binomial sampling methodology
that is used to determine mite density is applicable when inundative predator releases are
used for pest control. Given the current mass-rearing technology, a grower could afford
to introduce 50,000 predators per ha at a cost of about $500 per ha. This release rate is
equivalent to six predators per row-m when there are 8300 row-m of strawberries per ha.
Although effective predator: prey ratios have not yet been determined, studies conducted
with other mite systems (Collyer 1958; Hamai and Huffaker 1978; Waite 1988; and
Wilson et al. 1984) suggest that a ratio of 1:20 (6:120) is a reasonable estimate. Leaflet
densities increase through the season, but 120 twospotted mites per row-m is about 0.4
per leaflet in May (270 leaflets per row-m, 1984 data) and 0.3 per leaflet before mowing in
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 67
July (366 leaflets per row-m, 1984 data). As an action threshold, 0.4 pest mites per leaflet
is an order of magnitude below the threshold for spray application, therefore the Raworth
and Strong (1990) management plan is not valid when predators are released as a control
measure. Furthermore, the sampling methodology becomes increasingly unreliable as
mite density decreases below one mite per leaflet (Raworth 1986b). Sampling is still
useful, however, not to determine if twospotted mite densities are high enough to warrant
release of predators, but to determine whether the mite densities are low enough that the
predators have a chance of being effective. A density of five pest mites per leaflet, for
example, is equivalent to about 1500 per row-m. A release of 50,000 predators per ha at
this density would result in a predator: prey ratio of 1:250. Under this circumstance, a
grower should probably apply one spray to bring mite numbers down before releasing the
predators. Alternatively, if the samples are examined closely for predators, the grower
may find that there is little advantage in predator releases because there are substantially
more predators in the field than the number being released. A predator density of 0.1 per
leaflet is equivalent to about 40 per row-m, 7 x the 50,000 per ha release rate. Time and
experience are required to work out the details of an integrated biocontrol plan, but the
strategies must be considerably different from those in which pesticides are the only
method of control.
ACKNOWLEDGEMENTS
I thank G. Weller, C. Bast, T. Danyk, B. Smith and E Hagwall for technical assistance,
and K.W. Wu, J. McNamara and A. Borkent for identifications. Partial funding for the
project was provided by the Lower Mainland Horticultural Improvement Association
and the British Columbia Ministry of Agriculture and Food, Crop Protection Branch.
REFERENCES
Anonymous. 1968. Test methods for resistance in insects of agricultural importance: first conference. Bull.
Entomol. Soc. Am. 14:31-37.
Anonymous. 1986. Berry production guide for commercial growers. Province of British Columbia, Ministry of
Agriculture and Food.
Collyer, E. 1958. Some insectary experiments with predacious mites to determine their effect on the
development of Metatetranychus ulmi (Koch) populations. Ent. exp. & appl. 1:138-146.
Croft, B.A., A.W.A. Brown, and S.A. Hoying. 1976. Organophosphorus-resistance and its inheritance in the
predaceous mite Amblyseius fallacis. J. Econ. Entomol. 69:64-68.
Hamai, J. and C.B. Huffaker. 1978. Potential of predation by Metaseiulus occidentalis in compensating for
increased, nutritionally induced, power of increase of Tetranychus urticae. Entomophaga 23:225-—237.
Hoy, M.A. 1982. Genetics and genetic improvement of the Phytoseiidae. Pages 72-89 In Recent Advances in
Knowledge of the Phytoseiidae. M.A. Hoy, ed. Agric. Sciences Pub. University of California.
Mellor, EC., and H. Krezal. 1987. Strawberry mottle. Pages 10-15 Jn Virus Diseases of Small Fruits. R.H.
Converse, ed. U.S. Dep. Agric. Agric. Handb. 631. U.S. Government Printing Office, Washington, DC.
Raworth, D.A. 1986a. An economic threshold function for the twospotted spider mite, Tetranychus urticae
(Acari: Tetranychidae) on strawberries. Can. Entomol. 118:9-16.
Raworth, D.A. 1986b. Sampling statistics and a sampling scheme for the twospotted spider mite, Tetranychus
urticae (Acari: Tetranychidae), on strawberries. Can. Entomol. 118:807-814.
Raworth, D.A. and M. Merkens. 1987. Sampling the twospotted spider mite, Tetranychus urticae (Acari:
Tetranychidae), on commercial strawberries. J. Entomol. Soc. B.C. 84:17-19.
Raworth, D.A. and W.B. Strong. 1990. Development of a management protocol for the twospotted spider mite,
Tetranychus urticae Koch (Acari: Tetranychidae) on strawberries. Pages 103-116 Jn Monitoring and
Integrated Management of Arthropod Pests of Small Fruit Crops. N.J. Bostanian, L.T. Wilson and T.J.
Dennehy, eds. Intercept Ltd. England.
Shanks, C.H. Jr. 1965. Seasonal populations of the strawberry aphid and transmission of strawberry viruses in
the field in relation to virus control in western Washington. J. Econ. Entomol. 58:316-322.
Waite, G.K. 1988. Integrated control of Tetranychus urticae in strawberries in south-east Queensland. Exp.
Appl. Acarol. 5:23-32.
Wilson, L.T., M.A. Hoy, EG. Zalom and J.M. Smilanick. 1984. Sampling mites in almonds: I. The within-tree
distribution and clumping pattern of mites with comments on predator-prey interactions. Hilgardia
52(7):1-13.
68 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Notes on the longevity, fecundity and development of
Pissodes terminalis Hopping (Coleoptera: Curculionidae)
in the Interior of British Columbia, Canada
ERVIN KOVACS and JOHN A. McLEAN
FACULTY OF FORESTRY
THE UNIVERSITY OF BRITISH COLUMBIA
2357 MAIN MALL, VANCOUVER, B.C. V6T 1W5
ABSTRACT
The biology and life history of the lodgepole terminal weevil, Pissodes terminalis, was
studied in the interior of British Columbia, Canada. Average longevity of females of P.
terminalis was 112.8 days at 20°C. Mean lifetime fecundity was 115 eggs per female. The
egg stage lasted 8 days, and pupation took 15 days. In the field, egg laying started at the
beginning of June and all larvae reached the final instar by early September. Pupation
began in mid-September and at the end of the month the first adult was ready to emerge.
INTRODUCTION
Large areas of mature lodgepole pine (Pinus contorta Doug. ex Loud) in the Interior of
British Columbia have been infested during the last two decades by the mountain pine
beetle, Dendroctonus ponderosae Hopk. These have been managed by salvage logging
the infested forests and now there are large areas of young lodgepole pine forests. Such
stands are vulnerable to attack by regeneration pests (Amman and Safranyik 1984) one of
the most important of which is the lodgepole terminal weevil, Pissodes terminalis
Hopping.
Adults typically emerge from the leaders in early summer and after some maturation
feeding, the females lay eggs into the elongating terminal shoot of host trees. Newly
hatched larvae mine just beneath the epidermis; later instars burrow into the pith and
mine towards the apical bud. Pupation occurs in the pith. Most of the weevils overwinter
as late instar larvae but pupae and adults may also overwinter in the terminal.
Larval feeding in the phloem-cambium region and in the pith results in the death of
the terminal. Dead terminals are replaced by laterals, resulting in the formation of
crooks, forks in the main stem, and in severe cases, in multi-leadered crowns (Stevenson
and Petty 1968; Stevens and Knopf 1974; Duncan 1986). Beside deformities, the trees
also suffer height growth loss (Maher 1982; Amman and Safranyik 1984).
Leader clipping trials for the lodgepole terminal weevil (MoF 1984), as an experimen-
tal control method, have been carried out to reduce weevil numbers. Knowledge of the
biology and life history of the weevil can play an important role in the timing of leader
clipping operations. Although the impact of P. terminalis on young lodgepole pine trees
has been studied in the past (Maher 1982), no detailed information is available on this
pest’s biology in British Columbia. Our objectives were to investigate: the longevity and
fecundity of adult female P terminalis; the duration of egg and pupal stages; the
development of the weevil from egg to adult in field conditions.
METHODS AND MATERIALS
Longevity and fecundity.
Ten pairs of P. terminalis adults were placed in 0.5 L jars covered with cheese cloth and
kept at room temperature, 20 + 2°C. Each day a 10-cm-long section of lodgepole pine
terminal was placed in each jar from a supply of cut leaders that was kept refrigerated.
Numbers of feeding punctures, oviposition sites and numbers of eggs per oviposition site
were counted daily using a dissecting microscope.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 69
Table 1
Longevity and ovipositional characteristics of ten female Pissodes terminalis reared at 20 + 2°C.
Characteristics Mean +8S.D. Range
Longevity (days) 112.8 74.9 32-226
Preoviposition period (days) 10.1 6.8 2-22
Total eggs/female 115:0 6755 9-216
Eggs/oviposition site 0.94 : 0-2
Eggs/female/day** et 1.34 0.39-4.62
* §.D. not calculated
** From first to last day of oviposition
Duration of the egg stage.
Sections of the current year’s terminal growth with oviposition sites, obtained from the
longevity and fecundity experiment, were placed on moist paper towels in closed paper
boxes maintained at room temperature. Desiccation of the leaders was prevented by
moistening the paper towels daily. The eggs were checked daily and hatching recorded.
After each daily examination the oviposition sites were closed to prevent desiccation of
the eggs.
Duration of the pupal period.
Twenty weevil larvae were obtained from dissections of one-year-old infested lodgepole
pine leaders. Each larva was kept in a 3-4 cm long section of the leader which was placed
in a separate petri dish at 20 + 2°C. Dates of pupation and adult emergence were recorded
for each larva.
Development of P. terminalis in the field.
Weekly collections at Ellis Creek, 25 km east of Penticton, B.C., were made between
June 5, 1987 and September 30, 1987. Ten attacked leaders were clipped with a hand
pruner and taken back to the laboratory where they were dissected. Numbers of all
weevil developmental stages were recorded. To relate the weevil’s life history with leader
phenology, 25 lodgepole pine trees with unattacked terminals were randomly chosen and
marked with red plastic ribbon. A number was assigned to each tree so that repeated
measurements could be taken from the same tree. Elongation of the leaders was measured
and recorded every 7 days.
RESULTS AND DISCUSSION
Longevity and fecundity.
Average longevity of the 10 female P. terminalis was 112.8 days after emergence from the
puparia; one female lived for 226 days (Table 1). Fontaine and Foltz (1985) found that
longevity of adult female deodar weevils, Pissodes nemorensis Germar, was 130.5 days
(S.D. = + 63.3; range = 1-198) under laboratory conditions of 25 +1°C. McMullen
and Condrashoff (1973) reported that adults of Pissodes strobi (Peck) can live up to 4
years in the field.
We observed that female P. terminalis are able to lay eggs as early as 2 days following
emergence and therefore they do not require a long maturation feeding. The preoviposi-
tion period averaged 10.1 days (Table 1). In contrast, the corresponding time for P
nemorensis was 36.6 days (S.D. = 6.1; range = 28-47) at 25 + 1°C (Fontaine and Foltz
1985).
The first eggs were laid on the second day, after which oviposition increased until day
21 (Fig. 1). There was a sharp decline in the number of eggs laid between day 21 and day
28, but there was a resurgence of oviposition in the following 7 day period. A very
similar pattern was observed by Fontaine and Foltz (1985): after a period of increasing
oviposition by P. nemorensis, the number of eggs laid suddenly “declined to about one-
half its peak value on day 90, and then increased again until day 130.” They assumed that
70 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
10
8
a
See eal ne 2
=
s 2 =
nT =
é P
g 197 4 Ti
) 4)
O
Lu
5 2
ieee
1.21 42 63 84 105 126 147 168 189 210 231
DAYS IN REARING AT 20+2C
| —@— EGGS/FEMALE/DAY —+— LIVE FEMALES |
Fig. 1. Survival and fecundity of ten caged Pissodes terminalis females at 20 + 2°C.
100
90
80
ro)
or
= 70 ——
2 1ST INSTAR
a 60 SK
O 2ND INSTAR
Cae 7
<q 3RD INSTAR
a 40 ye
Lu
4TH INSTAR
7 90
Lu
a
20
10
@)
10 30 22 13 2 23
JUNE JULY AUGUST SEPTEMBER
DATE
Fig. 2. Larval development of Pissodes terminalis at Ellis Creek, near Penticton, B.C. in the
summer of 1987.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 76
changing host quality caused the decline. Oviposition by P. terminalis reached its peak
on day 35 and declined sharply afterwards, although more than half of the females were
still alive. The last egg was laid on day 80.
The mean fecundity was 115 eggs per female, although one female laid 216 eggs (Table
1). Total numbers of eggs laid by P. strobi (Graham 1926) and P. nemorensis (Fontaine
and Foltz 1985) averaged 115 and 284, respectively.
From the weekly field collections, a total of 1246 oviposition sites were counted and
1150 eggs were found, a mean of 0.94 eggs per oviposition site. This result is slightly
smaller than the reported 1.19 eggs per site for P nemorensis (Fontaine and Foltz 1985),
and 1.4 eggs per site for P. strobi on Sitka spruce, Picea sitchensis. (Gara et al. 1971).
Females of P. terminalis most often laid one egg per pit (91.6%), but sometimes they
oviposited two eggs (0.5%) or none (7.5%). Sealed but empty oviposition pits were most
often found towards the end of the oviposition period. Five eggs were laid directly on the
bark surface (0.4%). These results support previous findings that generally only one egg
is deposited in each pit (Drouin et al. 1963; Stark and Wood 1964). Females laid an
average of 1.57 eggs per day.
Duration of the egg stage.
Observation of 54 eggs of P. terminalis revealed that the average duration of the egg stage
was 8 days (S.D. = +0.98; range = 5-18). This is in agreement with the findings of
Stevens and Knopf (1974) who reported that eggs of P. terminalis hatch within 2 weeks.
We observed that two eggs hatched 5 days after oviposition and 9 took 18 days to hatch.
Duration of the pupal period.
Observations of 20 P. terminalis pupae showed that on an average it took 15 days (S.D. =
+ 2.5; range = 11-20) from pupation to adult emergence at 20°C.
Observations of the development in the field.
The first adult P. terminalis was observed on a one-year-old attack on May 10, 1987.
Neither an emergence hole nor fresh feeding punctures were observed on the terminal.
Six more adults were observed on elongating leaders within the next ten days. The
observations suggest that these weevils may have emerged in the previous fall and
overwintered probably in the duff.
Daily examination of 50 dead leaders, attacked in 1986 revealed the first weevil
emergence hole on June 19, 1987. However, the first current year’s attack was recorded on
June 3, 1987 suggesting that these eggs may have been laid by overwintering adults. The
last eggs were observed on July 22, 1987.
Figure 2 shows the development of P. terminalis in the field at Ellis Creek, near
Penticton, B.C. Prolonged egg laying by emerging adults and egg hatching resulted in
first-instar larvae being present from the beginning of June through July 22, 1987. This is
the date when the last second-instar larvae were recorded. In 1961, Stark and Wood
(1964) found that in central Sierra Nevada, California, first- and second-instar larvae of
P. terminalis were present until the end of July. In the present study, third-instar larvae
were observed in the pith from the end of June through the beginning of September, 1987
(Fig. 2). Last-instar larvae were found on July 14, 1987 and by the end of the month they
were commonly encountered. Ninety-five percent of the larvae were in the pith on Aug.
13, 1987. By September 9, 1987 all larvae reached the final instar. Stark and Wood (1964)
reported that all larvae were in the last instar on September 6, 1961.
The first pupa was recorded on September 17, 1987 and two weeks later the first adult
was ready to emerge. These observations suggest that, in this locality, P terminalis
overwinters as a fourth instar rather than a third instar larva. Pupae and adults also
overwinter inside the terminal. Emerged weevils probably hibernate in the duff (Furniss
and Carolin 1977).
72 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
overwintering larvae /pupae/adults
adult emergence from duff
leaders
oviposition
dispersal to new
larval feeding
overwintering larvae/pupae/adults
leader
100
Leader elongation
a
Fs
[e)
Ea
5
3 50
=
3
Ss
Elongation of the terminal of P. contorta
Jan Feb Mar Apr May Jun = Jul Aug Sep Oct Nov _— Dec
Fig. 3. Life cycle of Pissodes terminalis at Ellis Creek, near Penticton, B.C. in the summer of
1987.
On average, 3.4 larvae per tip (S.D. = +2.79; range = 1-17; n = 160) were found.
This number is slightly smaller than the 4.2 larvae per tip (range = 1-19; n = 305) found
by Stark and Wood (1964) in California. Since adult females oviposit into the elongating
terminal the coincidence of the greatest leader growth and ovipositional period is critical
for successful oviposition. Figure 3 shows the relationship between oviposition and tip
elongation at Ellis Creek in 1987. Leader growth started at the beginning of May and it
was practically finished by the end of July. Only slight height growth was recorded in the
first 2 weeks of August. Oviposition was restricted to the second half of the elongation
period. Figure 3 also summarizes field observations on the life cycle of the lodgepole
terminal weevil at Ellis Creek. Late-instar larvae, pupae and adults overwinter. Adult
weevils start emerging in early May and egg laying begins early June. By mid-September
all larvae reach the final instar and the first pupae are encountered in late September when
some of the adults emerge. The life cycle of P. terminalis follows type 1, 2A, 2B and 2C
life cycles described by Cameron and Stark (1989) from the Sierra Nevada.
ACKNOWLEDGEMENTS
We thank Drs. J.W.A. Harris, M.A. Hulme, M.B. Isman and Lorraine McLaughlin for
reviewing the manuscript, Christian Guimond for assisting with the field work and the
Agriculture Canada Summerland Station for providing laboratory space.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 q3
REFERENCES
Amman, G.D. and L. Safranyik. 1984. Insects of lodgepole pine: impact and control. Jn Lodgepole pine —the
species and its management. Baumgartner, D.H., R.G. Krebill, J.T. Arnott and G.E Weetman (Eds.).
Symp. Proc. Wash. State Univ. pp.107—124.
Cameron,E.A. and R.W. Stark. 1989. Variations in the life cycle of the lodgepole terminal weevil, Pissodes
terminalis Hopping (Coleoptera: Curculionidae), in California. Can. Ent. 121:793-801.
Drouin, J.A., C.R. Sullivan, S.G. Smith. 1963. Occurrence of Pissodes terminalis Hopping (Coleoptera:
Curculionidae) Jn Canada: life history, behavior, and cytogenetic identification. Can. Ent. 95:70-76.
Duncan, R.W. 1986. Terminal and root-collar weevils of lodgepole pine. Pac. For. Centre, Pest Leaflet FPL 73.
6pp.
Fontaine, M.S. and J.L.Foltz. 1985. Adult survivorship, fecundity, and factors affecting laboratory oviposition
of Pissodes nemorensis (Coleoptera: Curculionidae). Can. Ent. 117:1575-1578.
Furniss, R.L. and V.M. Carolin. 1977. Western Forest Insects. USDA For. Serv. Misc. Publ. No. 1339. 654 pp.
Gara, R.I., R.L.Carlson and B.F Hrutfiord. 1971. Influence of some physical and host factors on the behavior
of the Sitka spruce weevil, Pissodes sitchensis, in southwestern Washington. Ann. Ent. Soc. Amer.
64:647-671.
Graham, S.A. 1926. Biology and control of the white-pine weevil, Pissodes strobi Peck. Cornell Agric. Exp.
Stn. Bull. 449. 32 pp.
Maher, T.E 1982. The biology and impact of the lodgepole terminal weevil in the Cariboo Forest Region.
M.Sc. Thesis, Univ. of British Columbia. 63 pp.
McMullen, L.H. and S.F Condrashoff. 1973. Notes on dispersal, longevity and overwintering of adult
Pissodes strobi (Peck) (Coleoptera: Curculionidae) on Vancouver Island. J. Entomol. Soc. Brit. Columbia
70:22-26.
Ministry of Forests. 1984. Pest Management Progress. 3(2):23.
Stark, R.W. and D.L. Wood. 1964. The biology of Pissodes terminalis Hopping (Coleoptera: Curculionidae) in
California. Can. Ent. 96:1208-1218.
Stevens, R.E. and J.A.E. Knopf. 1974. Lodgepole terminal weevil in interior lodgepole pine forests. Environ.
Entomol. 3:998-1002.
Stevenson, R.E., and J.J. Petty. 1968. Lodgepole terminal weevil, (Pissodes terminalis Hopping) ‘in the
Alberta/Northwest Territories Region. Can. Dept. of For. Bi-monthly Res. Notes. 24:6.
Note on the occurrence of
Paravespula germanica (Hymenoptera: Vespidae)
in the Lower Fraser Valley of British Columbia
H.S. GERBER
B.C. MINISTRY OF AGRICULTURE AND FISHERIES
17720 - 57th AVENUE, SURREY, B.C., V3S 4P9
The German yellowjacket, Paravespula germanica (Fab.), was not known to occur in the
Pacific Northwest prior to 1981. The first collections of this wasp were made in 1981 in
Nampa, Idaho, and in 1982 in Puyallup, Washington (MacDonald and Akre, 1984).
Buckell and Spencer (1950) did not include P. germanica in their list of vespid wasps of
British Columbia. Akre et al. (1989) gave the range of this species in North America.
In the summers of 1984 and 1985, I netted yellowjacket workers in Cloverdale, B.C.
and keyed them to P. germanica using the key in Akre et al. (1980). These wasps were
sent to Akre, who confirmed their identity and retained them in the collection of the
Washington State University, Pullman.
74 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
In 1986 an active nest of P germanica was collected from a shed in Clearbrook. The
nest was attached to the rafters and the lower tip touched a ceiling joist, measuring 91 cm
long and 46 cm in diameter.
A small, globular (25 cm X 20 cm), active nest of P. germanica was collected from
the inside of a storage cabinet of a sailboat in Richmond in early September, 1987. The
boat had been built and moored there, eliminating the possibility that the nest might have
been built while the boat was elsewhere.
Also in October of 1987, a farmer from Clearbrook contacted me concerning a large
wasp nest in his barn. The nest was built between 5 cm x 30 cm ceiling joists on 40 cm
centers and projected about 45 cm below them. It contained 11 combs, all situated
between the ceiling joists. The mass of nesting material projecting below the ceiling
joists contained no combs. Many dead wasps inside the nest keyed to P. germanica.
In 1988, 2 active nests measuring 25 cm X 25 cm were collected from crawl spaces
under houses, | on 13 August from Aldergrove, and | on 30 August from White Rock.
Specimens were also collected from 2 ground nests, on 3 September from North Langley,
and on 30 September from Cloverdale. Further collections were made from 3 inaccess-
ible nests: on 22 September from a hole in a wall of a mobile home in Rosedale; on 30
September from the attic of a home in south Langley; and on 5 October from the floor of a
sundeck in Steveston.
On 18 July 1989, an active nest measuring 30 cm X 30 cm was taken from a large
trunk in a storage shed in White Rock. Further collections were made from 3 inaccessible
ground nests and | inaccessible nest in an attic as follows: 7 September — Vancouver, 11
and 28 September— Burnaby, and 3 October—south Langley. In addition to the collec-
tions reported above, Mr. M. Rabas collected P. germanica from Richmond on 10
September 1987 and deposited them in the Spencer Entomological Museum at the
University of British Columbia.
P. germanica belongs to a group of wasps that includes P pensylvanica and P.
vulgaris. It resembles P. pensylvanica except that the continuous yellow genal band
around the top of the compound eye is interrupted in P. germanica. In its behaviour it
resembles P. vulgaris, being very aggressive and defensive around its nest. Nest and
population size approach that of P. vulgaris, whereas external nest appearance and grey
color resemble that of P. pensylvanica. Its scavenging feeding habits, and its selection of
man-made structures for nesting sites brings this species in close contact with humans,
thus increasing the potential for wasp stings, which are considered to be a nuisance or
even a public health threat.
ACKNOWLEDGEMENT
I thank Dr. Roger D. Akre, Washington State University, Pullman, for criticizing the
manuscript.
REFERENCES
Akre, R.D., A. Greene, J.EMacDonald, P.J. Landolt, and H.G. Davis. 1980. Yellowjackets of America North of
Mexico. U.S. Department of Agriculture, Agriculture Handbook No. 552, 102 pp.
Akre, R.D., C. Ramsay, A. Grable, C. Baird, and A. Stanford. 1989. Additional range extension by the German
yellowjacket, Paravespula germanica (Fabricius), in North America (Hymenoptera: Vespidae). Pan-Pacific
Ent. 65(1):79-88.
Buckell, E.R. and G.J. Spencer. 1950. The social wasps (Vespidae) of British Columbia. Proc. Ent. Soc. of
British Columbia, 46:33-40.
MacDonald, J.E andR.D. Akre. 1984. Range extension and emergence of subterranean nesting by the German
yellowjacket, Vespula germanica, in North America (Hymenoptera: Vespidae). Ent. News 95(1):5-8.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 75
Emergence patterns of terminal weevils (Coleoptera:
Curculionidae) and their parasitoids from lodgepole pine
in the Interior of British Columbia, Canada
ERVIN KOVACS AND JOHN A. McLEAN
UNIVERSITY OF BRITISH COLUMBIA
FACULTY OF FORESTRY
270-2357 MAIN MALL, VANCOUVER, B.C. V6T 1W5
ABSTRACT
Three terminal weevil species emerged from 82 infested leaders collected at two locations
in the Okanagan Valley. The most abundant species was Pissodes terminalis Hopping.
Magdalis gentilis LeConte started to emerge at the beginning of May whereas P
terminalis and one species of Cylindrocopturus emerged a month later. Parasitoids reared
from weevil infested terminals belonged to nine species in six families of the Order
Hymenoptera. The most important species was the pteromalid Rhopalichus pulchripen-
nis Crawford but two species of Eurytoma collectively ranked second in abundance.
Emergence of the majority of the parasitoids preceded that of P terminalis and
Cylindrocopturus sp.
INTRODUCTION
Terminal weevils often cause serious damage to young coniferous trees by attacking
terminal shoots (Keen 1952). According to Keen (1952) the three most important genera
of twig weevils are Pissodes, Magdalis and Cylindrocopturus.
The lodgepole terminal weevil, Pissodes terminalis Hopping is the most important
weevil species attacking leaders of lodgepole pine, Pinus contorta Doug. ex Loud., in
British Columbia. The occurrence of Magdalis and Cylindrocopturus species in the
province has been reported by Furniss and Carolin (1977) but the first damage caused by
M. gentilis Lec. was observed and reported by the Forest Insect and Disease survey
(FIDS) only in 1987 (Wood et al. 1987).
Fellin and Schmidt (1966) reported that the damage caused by M. gentilis “did not
appear to be restricted to any particular portion of the crown.” Adults puncture needles
so that the distal portions desiccate and discolor (Fellin and Schmidt 1966), and are
broken off by wind, rain or snow (Plumb 1950; Fellin 1973). Fellin (1973) stated that
defoliation was the only type of damage he had observed. However, Kovacs’ (1988)
observations support the findings of Furniss and Carolin (1977) that larvae of M. gentilis
mine branches as well as leaders. Damage caused by Cylindrocopturus spp. 1s similar to
that of M. gentilis.
Leader clipping trials (MoF 1982, 1983, 1984) were carried out in the Cariboo Forest
Region to reduce populations of P. terminalis. Leaders were clipped in July. Development
of effective control methods requires they are consistent with the biology of the target
species.
Losses caused by M. gentilis and Cylindrocopturus spp. are not considered important
(Furniss 1942; Fellin 1973; Furniss and Carolin 1977) and therefore, no practical
measures have been developed for their control. In the absence of effective control
methods it seems that natural control will play the most important role in reduction of
numbers of these pests.
Detailed studies have been carried out on insects associated with Pissodes strobi
Peck. on eastern white pine, Pinus strobus L. (Harman and Kulman 1967), on Engel-
mann spruce (VanderSar 1978) and on Sitka spruce, Picea sitchensis Bong. (Carr.),
(Stevenson 1967; Alfaro et al. 1985). However, no information is available on the
parasite-predator complex of other leader weevils in British Columbia.
76 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Magdalis gentilis
Cylindrocopturus sp.
NUMBER OF WEEVILS
12 21 30 8 17 26 5 14
May June July
DATE
METHODS AND MATERIALS
In 1987, 737 dead leaders killed by terminal weevils were collected between May 7-11 in
young spaced lodgepole pine stands in the southern Interior of British Columbia. Most of
the leaders (641) were collected at Ellis Creek, 20 km east of Penticton and the rest (96)
on the Big White Road, 30 km southeast of Kelowna. The terminals were incubated
individually in cardboard mailing tubes. A small vial for trapping emerging weevils was
inserted into the lower half of one of the end caps. The tubes were maintained at
20 + 2°C. Emerging specimens were collected daily and either preserved in 70% alcohol
or pinned. Specimens were submitted to the Biosystematic Research Institute in Ottawa
for identification.
RESULTS AND DISCUSSION
Individual rearing, which started between May 7-11, 1987 revealed that in addition to P
terminalis, M. gentilis and Cylindrocopturus sp. were also present in the Penticton and
Kelowna areas. Earlier rearings by Kovacs (1988) showed that M. gentilis can also be
found in young lodgepole pine stands in the Cariboo Forest Region.
Weevils of all three species emerged from 82 lodgepole pine leaders (11.1%), whereas
parasitoids emerged from 127 terminals (17.4%). The low emergence rate was probably
the result of desiccation of the terminals in the mailing tubes which resulted in the death
of larvae and pupae.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 a
15
se al i“ ! Me nooo At» Bterminalis
Se eoaqllee [-: eee ee eee Repuichripennis
pa ar ==29- Nene [Sete zeae ce D. terebrans
---U-U------U- UU UU ue ~~ - - --- Eurytoma spp
-------¥---U----- See Allodorus sp.
SRS 92 OS SR Mesopolobus sp.
hails ag cig areas aaa ea |e eee een D. japonica
Aglare tert cee ea tft ar iene nee Hyssopus sp.
10
Number of Insects
DATE
The first weevil species to emerge from dead leaders under laboratory conditions was
M. gentilis which started emerging on May 12, 1987 and finished seven days later (Fig. 1).
On June 3, 1987 (30 days in rearing) P. terminalis started to emerge and it reached its
peak on June 7, 1987 (Fig. 2). Emergence continued until July 7, 1987. Cylindrocopturus
sp. emerged between June 10, 1987 and July 16, 1987 (Fig. 1). The constant temperatures
in the rearing regime meant that this material accumulated a thermal heat sum at a
greater rate than was occurring under diurnal forest conditions. Reared material was
approximately 12 days ahead by the end of June, calculated above a threshold tempera-
ture of 5°C. Enhanced heat sum accumulation needs to be considered when referencing
the temporal sequences in Figs. 1, 2.
Many parasitoids were also reared from the terminals. They belonged to six families
in the order Hymenoptera (Table 1). As leaders were attacked by a terminal weevil
complex correct association between individual host species and parasitoids cannot be
assured. In the course of this study neither predators nor entomophagous fungi were
found in association with any of the weevils.
All samples were dominated by Rhopalicus pulchripennis Crawford (Hym.: Ptero-
malidae) and two species of Eurytoma (Hym.: Eurytomidae) collectively ranked second
in abundance. Dolichomitus terebrans nubilipennis (Viereck) (Hym.: Ichneumonidae)
was particularly abundant on one of the sites east of Penticton. These parasitoids have
also been reported to attack P. strobi (VanderSar 1978; Alfaro et al. 1985). One
Mesopolobus species has also been reported as a parasitoid of P. terminalis (Stevens and
Knopf 1974).
Figure 2 shows emergence patterns of the parasitoids from infested lodgepole pine
leaders in relation to that of P. terminalis. The parasitoid complex had a bimodal
emergence pattern. Most of the parasitoids emerged earlier than P. terminalis. D.
terebrans emerged between May 8-11 and the peak occurred on May 10, 1987. Stevenson
(1967) reported that D. terebrans emerged in the field from late May to the third week of
June with a peak about mid-June. The pteromalid R. pulchripennis started to emerge on
May 20, 1987 and emergence was completed on June 2, 1987. Emergence of the two
eurytomids lasted for a month and was fairly constant.
It was observed that one of the sites on a south facing slope had high numbers and a
wide variety of parasitoids. This site supported an abundance of fireweed, Epilobium
angustifolium L. and one species of lupin, Lupinus. Several adult parasitoids were
observed feeding on nectar of these plants.
78 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Table 1
Hymenopterous parasitoids found associated with terminal weevils in British Columbia, 1986-1987.
Family Genus/Species Location Relationship Time of
to weevils emergence
Braconidae Allodorus sp. Kelowna Endoparasitoid Spring
Penticton
Prince George
Williams Lake
Coeloides Kelowna Ectoparasitoid Spring
rufavariegatus (Prov)
Eulophidae Hyssopus sp. Kelowna Endoparasitoid Summer
Penticton
Eurytomidae Eurytoma spp. Kamloops Ectoparasitoid Summer
Kelowna
Merritt
Penticton
Prince George
Williams Lake
Ichneumonidae Dolichomitus Penticton Ectoparasitoid Spring
terebrans Williams Lake
nubilipennis
(Ratzeburg) Penticton Ectoparasitoid Spring
Delomerista
Japonica
Cushman
Pteromalidae Rhopalichus Kamloops Ectoparasitoid Summer
pulchripennis Cwfd. Kelowna
Merritt
Penticton
Prince George
Williams Lake
Mesopolobus sp. Kamloops unknown Summer
Merritt
Peuticton
Scelionidae Telenomus sp. Kamloops Endoparasitoid Summer
Williams Lake
MANAGEMENT IMPLICATIONS
Leader clipping trials near Prince George in the early 1980s (MoF 1984) failed to have
any effect on the weevil population as clipping was done in July, a time when most
weevils had probably already emerged. Therefore, knowledge of emergence patterns of
the weevils is important in planning leader clipping projects. Early emergence of
Magdalis gentilis suggests that clipping should be carried out by early spring.
Field observations indicated that the best time for clipping is February because almost
all attacked leaders have already changed color to a dull brown by this time which
facilitates recognition of infested terminals. Experience has also shown that the top of
the snow is hard in February which facilitates easy walking in the stands. In addition, the
depth of the snow helps the worker to reach the infested leaders and minimizes bending
of the cold-brittle trees. The only disadvantage of February leader clipping is that many
parasitoids would be removed in the leaders. Parasite enhancement techniques such as
containing the clipped leaders in a mesh covered drum, as has been proposed for P. strobi
(Hulme et al. 1987) might be successfully implemented for P. terminalis.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 79
ACKNOWLEDGEMENTS
This research was funded by the Forest Research Development Agreement, Project
number F52-31-008. We thank D.E Bright, J.R. Barron, G. Gibson, L. Masner and M.
Sharkey of the Biosystematics Research Institute in Ottawa for identifications.
REFERENCES
Alfaro,R.I., M.A. Hulme, and J.W.E. Harris. 1985. Insects associated with the Sitka spruce weevil, Pissodes
strobi (Col.: Curculionidae) on Sitka spruce, Picea sitchensis, in British Columbia, Canada. Entomophaga
30(4):415-418.
Fellin,D.G. 1973. Weevils attracted to thinned lodgepole pine stands in Montana. USDA Forest Service,
Research Paper INT-136. 20 pp.
Fellin,D.G. and W.C. Schmidt. 1966. Magdalis gentilis Lec. A newly discovered pest of forest regeneration in
Montana. Mont. Acad. Sci. Proc. 26:59-60.
Furniss,R.L. 1942. Biology of Cylindrocopturus furnissi Buchanan on Douglas-fir. J. Econ. Entomol. 35:853-
859.
Furniss,R.L. and V.M. Carolin. 1977. Western Forest Insects. USDA Forest Service Misc. Publ. No.1339 654
p.
Harman, D.M. and H.M. Kulman. 1967. Parasites and predators of the white pine weevil, Pissodes strobi
(Peck). Univ. of Maryland, Nat. Res. Inst. Contrib. 323. 35 pp.
Hulme, M.A., J.W.E. Harris and A.F Dawson. 1987. Exploiting adult girth to separate Pissodes strobi (Peck)
(Coleoptera: Curculionidae) from associated insects in leaders of Picea sitchensis (Bong.) Carr. Can.
Entomol. 119:751-753.
Keen,EP. 1952. Insect Enemies of Western Forests. USDA Misc. Publ. 273 280 pp.
Kovacs,E. 1988. Terminal weevils of lodgepole pine and their parasitoid complex in British Columbia. M.Sc.
Thesis, University of B.C. 107 pp.
Ministry of Forests and Land. 1982. Pest Management Progress. 1(2):8-9.
Ministry of Forests and Land. 1983. Pest Management Progress. 2(2):14
Ministry of Forests and Land. 1984. Pest Management Progress. 3(2):23-24
Plumb,G.H. 1950. The adult feeding habit of some conifer-infesting weevils. Can. Ent. 82: 53-57.
Stevens, R.E. and J.A.E. Knopf. 1974. Lodgepole terminal weevil in interior lodgepole pine forests. Environ.
Entomol. 3:998-1002.
Stevenson,R.E. 1967. Notes on the biology of the Engelmann spruce weevil, Pissodes engelmanni (Coleop-
tera: Curculionidae) and its parasites and predators. Can. Ent. 99: 201-213.
VanderSar,T.J.D. 1978. Emergence of predator and parasites of the white pine weevil, Pissodes strobi
(Coleoptera: Curculionidae) from Engelmann spruce. J. Entomol. Soc. Brit. Columbia 75:14-18.
Wood,G.S., G.A. Van Sickle and L. Humble. 1987. Forest Insect and Disease Conditions, British Columbia
and Yukon, 1987. Can. For. Serv., Pac. For. Centre BC-X-1987 32 pp.
Compatibility of the winter moth parasitoid
Cyzenis albicans (Tachinidae) with pesticide use in the
cultivation of blueberries in the Fraser Valley
JENS ROLAND* AND SUNNY SZETO
AGRICULTURE CANADA RESEARCH STATION
6660 N.W. MARINE DRIVE, VANCOUVER, B.C. V6T 1W5
* PRESENT ADDRESS:
DEPT. OF BOTANY, UNIVERSITY OF ALBERTA
EDMONTON, ALBERTA T6G 2E9
ABSTRACT
The potential for the use of the tachinid fly, Cyzenis albicans Fall., as an alternative
control of winter moth, Operophtera brumata L. on blueberries was evaluated with
respect to the flies’ compatibility with late season clean-up insecticide sprays. Pupae of
Cyzenis suffered no greater mortality when exposed to malathion sprays than did those
not exposed to such sprays. Mechanisms of protection for the tachinid from insecticides
and its potential for biologicat centrol in blueberries are discussed.
80 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
INTRODUCTION
One of the major problems associated with the introduction or conservation of natural
enemies for the control of pests in agricultural crops, is the incompatibility of the control
agents with the use of pesticides. Well established crops typically have a standard
regimen of insecticide application; the success of biological control agents must then be
evaluated within the context of pesticide use. This problem is exacerbated by the
tendency for natural enemies to be affected more severely by insecticides than are their
hosts (Bartlett, 1964).
An increasing problem in blueberry (Vaccinium corymbosum) cultivation in the
Fraser Delta has been the spread of the introduced winter moth, Operophtera brumata
(Geometridae), from Vancouver Island (Embree and Otvos, 1984). Two features of the
biology of this insect makes control difficult: 1. early hatch (late March to early April)
results in first- and second-instar larvae feeding inside unopened buds making detection
difficult until heavy damage has occurred, and 2. feeding by larvae is greatest during
the period of blueberry bloom when pesticides cannot be applied because of bee activity.
Commercial production of blueberries in the Lower Fraser Valley, British Columbia,
utilizes a number of insecticidal sprays in spring for the control of lepidopterous larvae,
especially geometrids and tortricids, and in summer for pre-harvest control of a wide
variety of insects (British Columbia Ministry of Agriculture and Fisheries, 1988). The
difficulty of winter moth control using insecticides could be potentially reduced by the
use of natural enemies. The tachinid fly, Cyzenis albicans (Tachinidae), has contributed
to control of winter moth in oakwoods (Embree, 1971, Roland, 1988, 1990). Cyzenis may
be a useful addition to the current practice of blueberry cultivation reducing the need for
spring application of insecticides, provided that the flies are not affected by the late-
season (pre-harvest) insecticide sprays. This paper addresses the compatibility of
Cyzenis albicans with late-season insecticide applications.
Insect phenology
Winter moth larvae feed on the foliage of many deciduous trees and shrubs until late
May. Cyzenis albicans emerge from the soil in April, and oviposit on foliage on which
host larvae are feeding. Parasitoid eggs are ingested by the feeding host caterpillars.
Fully-fed, final instar caterpillars drop to the ground to pupate in late May and early June.
Both the parasitized and unparasitized caterpillars pupate in the soil at a depth of 2-3 cm
(Roland, 1986a). Within three to four weeks, in late June, Cyzenis maggots have ©
completed feeding, and pupate inside the host’s pupal case and cocoon. Cyzenis remain
in the soil as pharate adults within their puparia until the following spring. Unparasitized
winter moth pupae remain in the soil only until November or December when they
emerge as adults. Both Cyzenis and its host would be present in the soil at the time of the
pre-harvest clean-up spray.
MATERIALS AND METHODS
Cyzenis albicans were obtained in May 1988, by collecting parasitized hosts in an
unsprayed apple orchard in Victoria, B.C. (sites described in Roland, 1986b). Twenty
cocoons were placed in each of sixteen 15-cm diameter Petri dishes filled with damp peat
soil collected from a commercial blueberry field (Richland Farms, Richmond, B.C.).
Eight of the 16 dishes were exposed to Malathion spray in the field on June 26, by placing
dishes under blueberry bushes, the normal location for winter moth pupation. Malathion
50 EC (500 g malathion/litre) was applied at the rate of 550 g a.1./ ha; the recommended
rate for pre-harvest insect control on blueberries (British Columbia Ministry of Agricul-
ture and Fisheries, 1988). The eight control dishes were similarly set out in the field, but
were not exposed to insecticide spray. Dishes were collected after | h, and kept in
separate cages inside a screened shade house. The proportion of Cyzenis flies emerging
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 81
the following spring was recorded for each replicate. The proportions surviving in the
treatments and controls were compared with a one-way Analysis of Variance after
transformation by arc-sine square-root.
RESULTS AND DISCUSSION
There was no effect from late-season malathion sprays on the survival of Cyzenis
(F=1.08, df=1, P=0.32). Over-all, 96% of Cyzenis survived in the control replicates,
97% survived in replicates which had been sprayed with malathion. Preharvest sprays
with malathion appeared to have no effect on the survival of Cyzenis. Insecticides
containing organochlorine, organophosphate and carbamate are known to be inactivated
in soils high in organic matter probably because of adsorption. The mechanism of
inactivation, however, is not clear. Harris (1964), demonstrated that in moist soils
inactivation of insecticides such as heptachlor, DDT, diazinon, V-C 13 and parathion was
proportional to the organic content of the soil. The absence of any impact of malathion on
Cyzenis mortality may be due to the strong adsorption to, and inactivation in, the moist
organic peat in which blueberries are typically grown. Another contributing factor may
be the rapid degradation of malathion in soil. Malathion is known to be non-persistent in
soils (Mulla et al., 1981). Under field conditions, 85% of malathion residues were lost
from a silt loam during the first three days following application (Lichtenstein and
Schulz, 1964). Malathion persisted least in moist soils (Lechtenstein and Schulz, 1964).
Rapid disappearance ensures that malathion would have no residual effect on Cyzenis
mortality. If Cyzenis albicans were to be used as an adjunct to current control of winter
moth larvae in early spring, it appears that they will not suffer from clean-up sprays
applied late in the summer. Biological control agents which pupate in damp organic soils,
typical of blueberry production, may have enhanced suitability because they are not
susceptibile to insecticides.
ACKNOWLEDGEMENTS
We thank Richland Farms, Richmond, B.C. for permission to conduct this study on their
property.
REFERENCES
British Columbia Ministry of Agriculture and Fisheries, 1988. Berry Production Guide. 68 pp.
Bartlett, B.R. 1964. Integration of chemical and biological control. Jn (P. DeBach, ed.) Biological Control of
Insect Pests and Weeds. pp. 489-511. Chapman and Hall, London.
Embree, D.G. 1971. The biological control of the winter moth in eastern Canada by introduced parasites. In
Biological Control (Ed. by C.B. Huffaker), pp. 217-226.
Embree, D.G. and I.S. Otvos. 1984. Operophtera brumata (L), winter moth (Lepidoptera: Geometridae). Jn
(J.S. Kelleher and M.A. Hulme, eds.) Biological Control Programmes Against Insects and Weeds in
Canada 1969-1980, Commonwealth Agricultural Bureaux, Slough. pp. 353-357.
Harris, C.R. 1964. Influence of soil type and soil moisture on the toxicity of insecticides in soils to insects.
Nature 202:724.
Lichtenstein, E.P. and K.R. Shulz. 1964. The effect of moisture and microorganisms on the persistence and
metabolism of some organophosphorus insecticides in soil with special emphasis on parathion. J. Econ.
Entomol. 57:618-627.
Mulla, M.S., L.S. Mian and J.A. Kawecki. 1981. Distribution, transport, and fate of the insecticides malathion
and parathion in the environment. Residue Reviews 81:25.
Roland, J. 1986a. Success and failure of Cyzenis albicans in controlling its host the winter moth. Ph.D. thesis,
University of British Columbia, Vancouver.
Roland, J. 1986b. Parasitism of winter moth in British Columbia during build-up of its parasitoid Cyzenis
albicans: attack rate on oak v. apple. Journal of Animal Ecology 55:215—234.
Roland, J. 1988. Decline in winter moth populations in North America: direct versus indirect effect of
introduced parasites. Journal of Animal Ecology 57:523-531.
Roland, J. 1990. Interaction of parasitism and predation in the decline of winter moth in Canada. Jn Population
Dynamics of Forest Insects (Ed. by A.D. Watt, N. Kidd, S. Leather and M. Hunter). Intercept Publishers,
Andover, pp. 289-302.
82 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Efficacy of the nematode, Heterorhabditis heliothidis
(Rhabditida: Heterorhabditidae) against the peachtree borer,
Synanthedon exitiosa (Lepidoptera: Sesiidae) in peach trees
J.E. COSSENTINE, F.L. BANHAM, AND L.B. JENSEN
AGRICULTURE CANADA RESEARCH STATION
SUMMERLAND, BRITISH COLUMBIA V0H 1Z0
ABSTRACT
A suspension of Heterorhabditis heliothidis Khan, Brooks and Kirschmann, sprayed in
mid-June onto the trunks of peach trees infested with peachtree borer (PTB) Synanthedon
exitiosa (Say) larvae significantly (P <.05) reduced the numbers of PTB adults that
eclosed from the feeding tunnels. Injections of nematode suspensions into and on the
outside of active PTB tunnels did not reduce the number of emerging PTB adults to a level
significantly (P <.05) lower than those emerging in the control cages. The study also
confirms that the larvae of the peachtree borer require up to 2 years to complete
development in stone fruit trees in the southern interior of British Columbia.
INTRODUCTION
The peachtree borer (PTB), Synanthedon exitiosa (Say) attacks most stone fruit trees and
is a particularly serious problem on peaches, nectarines, apricots, prunes and plums in
the southern interior of British Columbia. King and Morris (1956), as well as Madsen
and Procter (1982), reported this species to have one generation per year in western North
America in which adults are active through the summer. Female moths oviposit several
hundred eggs on the trunks of stone fruit trees near the soil line (Anthon, 1949) and on
the trunk bark up to a height of 60 cm above the soil line as well as on adjacent grass and
weed foliage in stone fruit blocks with dense, deep cover crops (EL. Banham, pers.
commun. ). The PTB larvae bore into the tree bark and feed by tunnelling in the cambium
layer at or below the soil line. The tender bark and sapwood of nursery seedlings and
young transplants makes them particularly vulnerable to larval attack. Young trees are
frequently killed by the girdling injury. Severe feeding damage, even in older trees
causes loss of vigor and increased vulnerability to secondary pests (Madsen and Procter,
1982). Chemical control of PTB is required to protect the trunks of stone fruit trees from
larval feeding injury throughout the growing season. Once larvae have bored into the
tree trunks they are protected from contact with conventional commercial control
chemicals by the brown sawdust frass and sap gummosis exudate that plugs the feeding
tunnels. Entomogenous nematodes have been shown to control boring insects in the
family Sesiidae under field conditions (Simons 1978; Bedding and Miller 1981). The
efficacy of the nematode, Heterorhabditis heliothidis Khan, Brooks and Hirschmann,
was investigated as a possible biological alternative to chemical control of PTB larvae
within their protected tunnels.
MATERIALS AND METHODS
A 0.12 ha block of Early Redhaven and Redhaven peach trees, located in an orchard in
Osoyoos, British Columbia, was chosen for investigation. Grass, weeds and soil, to a
depth of 5 cm, were pulled away from the bases of 40 PTB-infested trees 15 June, 1987.
Frass at the entrance to PTB tunnels was scraped away and the number of active tunnels
per tree assessed. The trees were irrigated at the trunk base by sprinklers on the day and
evening prior to treatment.
Heterorhabditis heliothidis nematodes, provided by Phero Tech Inc. (Vancouver,
B.C.), were applied to trees in the following treatments: a 200 ml spray of 200 nematodes
per ml water around the base of the tree using a calibrated backpack sprayer; 2 ml
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 83
TABLE 1
Percentages of peach tree borer adults emerging from active feeding tunnels
up to 90 days post-nematode treatment. 1987.
Treatment % adults eclosing!(n)
Control | 20.14a (52)
Syringed inside tunnel TAG ab: G5)
Syringed outside tunnel 7.14 ab (51)
Sprayed at base of tree 3.97b (43)
1. Percentages transformed before analysis using an arcsin transformation. Means followed by by the same
letter are not significantly different (P > .05) as determined by Duncan’s multiple range test.
injections of 500 nematodes per ml with a syringe into each active peachtree borer
tunnel; and, applications of 2 ml of 500 nematodes per ml to the outside of each active
tunnel. Each treatment was applied to 10 trees in a completely randomized design which
included 10 control trees. On the day of treatment the humidity was 58% and the
temperature 28°C.
Saran screen (32 mesh) trunk cages were fitted around the base of each of the 40 trees
immediately after the numbers of active tunnels were determined and the treatments
applied. Each cage formed a cone approximately 70 cm in diameter and 60 cm high with
an 8 cm wide sponge rubber collar wrapped and tied tightly around the tree trunk. The
edges of the screen were folded twice and stapled from the collar to below the soil. The
bottom of each cage was buried in soil to a depth of at least 5 cm. Ten, fourth- and fifth-
instar PTB larvae were removed from untreated peach trees and were exposed to H.
heterorhabditis in the laboratory to establish survival.
From early July, after the first PTB adults were caught in Zoecon R PTB pheromone-
baited traps within the test orchard, until the end of September, the trunk cages were
lifted 4 times at 3-week intervals and the numbers of emerged PTB adults counted. Ten of
the trunk cages were left on control trees and inspected at 6-week intervals the following
year in late July and August. No evidence of rodents was found under the tents.
RESULTS AND DISCUSSION
Lower percentages of PTB emerged from H. heliothidis treated than from untreated trees
(Table 1). The nematode spray around the base of the peach tree significantly (P <.05)
reduced the percentage of emerging adults when compared to the emergence level from
the control trees. Percentage PTB adult emergence was calculated based on the number
of infested tunnels observed before treatment. Percentages were transformed using an
arcsin transformation before analysis.
The soil-inhabiting entomogenous nematode H. heliothidis is capable of parasitizing
a wide range of insects (Khan et al. 1976) including PTB larvae under laboratory
conditions (pers. communication, T.A. Rutherford, Research Associate, Simon Fraser
University, Burnaby, B.C.). All PTB larvae exposed to the nematode in the laboratory
the day of the field release died in 7 to 14 days and nematodes were found within those
sampled. In the second larval stage H. heliothidis penetrates host larvae through the
mouth, spiracles and anus (Wouts 1979). Once inside a host the nematode releases a
symbiont bacterium, Xenorhabdus luminescens Thomas and Poinar (Thomas and
Poinar, 1979). Within 24 hours the bacterium multiplies and causes damage to all major
internal host organs (Wouts, 1984). This restricts host feeding and movement and
ultimately kills the insect while the nematode multiplies within. Nematodes are suscept-
ible to ultra violet radiation and low humidity (Finney, 1981). Promising results in
nematode field tests have followed nematode releases in damp environments and
complete host control has been obtained with nematode application within the dark and
84 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
moist environment of wood-borers in the family Sesiidae (Bedding and Miller 1981;
Simons 1978; Wouts 1984). The plugged, moist PTB tunnels located beneath the bark
would theoretically provide a parasitic nematode with an ideal humid environment in
which to move and multiply. Infective juvenile H. heliothidis are believed to find hosts by
following host chemical attractants (Bedding and Akhurst 1975).
Suppression of PTB by H. heliothidis within infested peach trees shows promise as a
potential control treatment that could decrease the need for routine protective chemical
sprays. The importance of time, number and rate of application(s) of the nematode
should be examined in future studies. Nematode treatment may be practical in an orchard
setting as the trunk spray was equally successful as the more laborious and hence more
expensive injections. Also, the tree trunk and surrounding soil can be easily moistened in
most commercial orchards with irrigation systems. Peachtree borer survival and emer-
gence within the control trees was only 20.1% by the end of the first summer test period
(1987). When cages were removed from the 10 control trees the following summer (1988)
they were found to contain 4 PTB moths and 15 uneclosed pupae. Three of the adult PTB
found in the second year were alive indicating that they had emerged during the summer
of 1988. Eclosed male and female PTB moths were not found co-existing in any of the
control tents during the 1987 summer trials, eliminating the possibility of the second
year PTB being a result of oviposition within the tents. The emergence of these adults
substantiates previous observations that some PTB larvae require two growing seasons to
complete development within stone fruit trees in British Columbia.
REFERENCES
Anthon, E.W. 1949. The peach tree borer. The state college of Washington Agriculture Experiment Stations
Institute of Agricultural Sciences. Station Circular No. 77. 3 pp.
Bedding, R.A. and R.J. Akhurst. 1975. A simple technique for the detection of insect parasitic rhabditid
nematodes in soil. Nematologica. 21:109-110.
Bedding, R.A. and L.A. Miller. 1981. Disinfesting blackcurrant cuttings of Synanthedon tipuliformis, using
the insect parasitic nematode, Neoplectana bibionis. Environ. Entomol. 10:449-453.
Finney, J.R. 1981. Potential of nematodes for pest control. pp: 603-620 Jn Microbial control of pests and plant
diseases. ed. H.D. Burges. Academic Press. 949 pp.
Khan, A., W.M. Brooks, and H. Hirschmann. 1976. Chromonema heliothidis n. gen., n. sp. (Steinernematidae,
Nematoda), a parasite of Heliothis zea (Noctuidae, Lepidoptera), and other insects. J. Nematol. 8(2):159-
168.
King, D.R. and H.F Morris. 1956. Biologies of the peach tree borer and lesser peach tree borer in east Texas. J.
Econ. Entomol. 49:387-398.
Madsen, H.E and PJ. Procter. 1982. Insects and Mites of tree fruits in British Columbia. Ministry of
Agriculture and Food. Victoria, B.C. 79 pp.
Simons, W.R. 1978. Preliminary research on entomophagous nematodes in particular on Neoplectana species
in the Netherlands. Med. Fac. Landbouww. Rijksuniv. Gent, 43(2):765-768.
Thomas, G.M. and G.O. Poinar. 1979. Xenorhabdus gen. nov., a genus of entomophathogenic nematophilic
bacteria of the family Enterobacteriaceae. Int. J. Systematic Bacteriol. 29(4):352-360.
Wouts, W.M. 1979. The biology and life cycle of a New Zealand population of Heterorhabditis heliothidis
(Heterorhabditidae). Nematologica 25:191—202.
Wouts, W.M. 1984. Nematode parasites of lepidopterans. Jn Plant and insect nematodes. Ed. Nickle, W.R. New
York, USA; Marcel Dekker, Inc. 636-655. Mt. Albert Res. Cen., Auckland, New Zealand.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 85
A preliminary survey of Collembola
in forest nurseries of British Columbia
VALIN G. MARSHALL
FORESTRY CANADA, PACIFIC FORESTRY CENTRE
506 WEST BURNSIDE ROAD, VICTORIA, B.C. V8Z 1M5
GWEN M. SHRIMPTON
BRITISH COLUMBIA MINISTRY OF FORESTS
3605-192nd STREET, SURREY, B.C. V3S 4N8
JEFFREY P. BATTIGELLI
GRADUATE STUDENT, DEPARTMENT OF SOIL SCIENCE
UNIVERSITY OF BRITISH COLUMBIA, VANCOUVER, B.C. V6T 2A2
ABSTRACT
A survey of 24 forest nurseries in British Columbia yielded 22 collembolan taxa, 10 of
which are reported for the first time in this province. The species most frequently
encountered was Sminthurinus quadrimaculatus, which was represented in 13 of the
nurseries. Only one of the species collected, Bourletiella hortensis is a known pest of
conifer seedlings, but it is not an obligate phytophage. The presence of sarophagous
Collembola and predatory actinedid mites in the samples suggests that pest collembolan
species are being controlled naturally by competition for food and by mite predators.
KEY WORDS: Forest nursery, Pest management, Acari, Collembola, Bourletiella
hortensis, Isotomurus palustris.
RESUME
Au cours de l’inspection de 24 pépiniéres forestiéres en Colombie-Britannique, on a
relevé la présence de 22 taxons de collemboles, dont 10 étaient signalés pour la premiére
fois dans cette province. L’espéce la plus fréquemment observée a été Sminthurinus
quadrimaculatus, qui était présente dans 13 pépiniéres. Une seule des espéces recueillies,
Bourletiella hortensis, est un ravageur connu des semis de coniféres, mais elle n’est pas un
phytophage obligatoire. La présence de collemboles saprophages et d’acariens acti-
nédides prédateurs dans les échantillons donne a penser que deux facteurs naturels
interviennet dans la limitation des populations de collemboles ravageurs: la compétition
pour la nourriture et les acariens prédateurs.
INTRODUCTION
This report deals with Collembola collected from three bareroot and 21 container
nurseries in British Columbia. Bareroot nurseries are traditional nurseries where seeds
are planted outdoors in the soil. In container nurseries, seedlings are grown in individual
containers in greenhouses, shelterhouses, or outdoor compounds where growing media
and environmental conditions are more rigorously controlled. Collembola occur in all
nurseries in British Columbia, but so far few have been identified to species (Sutherland
et al. 1989).
Collembola, or “springtails,” are minute arthropods, usually less than 1 cm long. The
largest species known, Tetrodontophora bielanensis (Waga), measures up to 8 mm
(Wallwork 1970). The Collembola have traditionally been classified in the Apterygota or
primitive, wingless insects. However, the relationship of Collembola to the Insecta is
uncertain and Scudder et al. (1979) considered them a separate Class in the Superphylum
Arthropoda. Collembola are known from Devonian fossils and have a number of unique
characteristics (Richards 1979). These include six abdominal segments that bear three
peculiar appendicular derivatives: a collophore, tenaculum and furcula (springing
organ). The furcula might be reduced or absent in some taxa. Collembola may also have a
postantennal organ. Pronounced sexual dimorphism is rare. All species moult through-
out their life.
86 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
The classification of the Collembola is controversial, but two orders (Arthropleona
and Symphypleona) are generally recognized (Kevan 1980). Ordinal division is based
primarily on shape of the abdomen. The Symphypleona are characterized by a globular
abdomen that lacks distinct segments; Arthropleona have an elongate abdomen that is
usually divided into six distinct segments. About 4450 species and subspecies have been
described world-wide (Salmon 1964) and at least 520 are estimated to occur in Canada
(Richards 1979). These estimates are very conservative because hundreds more species
have been described since Salmon’s 1964 compendium and in Canada the Collembola
have not been extensively studied (Danks 1988).
Members of both orders feed on a wide range of organic materials and springtails
occur wherever plants grow, including Antarctic and Arctic Islands. Collembola may be
present in large numbers in forest soils and during mass emergence or swarming,
estimates of over 1 million per m2 have been reported (Christiansen 1964).
METHODS
In 1987-88, Collembola were hand-collected from styroblocks of container nurseries.
Fine camel’s-hair brushes were used to sweep specimens directly into vials (2.5 cm
diameter) to which 75% ethanol was then added. Specimens were generally numerous on
the sides and upper surfaces of styroblocks and this method proved more successful than
aspiration. Collections in bare root nurseries were made form the soil surface in 1971-72
by the grease-film method (Marshall and IInytzky 1976). Collembola in bareroot
nurseries, such as Koksilah and Green Timbers, are a source of inoculum for container
nurseries that are built on the same site or when the former are converted to container
nurseries.
Collembola were cleared by the Hille Ris Lambers method (Spencer 1959) and
mounted in a modified Swann medium (Rusek 1974). A minimum of six individuals from
each representative group were prepared for mounting; where less than six individuals
were available, all specimens were mounted.
Species identifications were made from Christiansen and Bellinger (1980), but the
family and generic classification mainly follow Salmon (1964) in order to better relate the
results to the world fauna. In many cases, subgeneric designations in Christiansen and
Bellinger (1980) corresponded to genera in Salmon; where there was disagreement an
annotation is given for the name used herein.
RESULTS AND DISCUSSION
Twenty-two Collembolan taxa were identified from the 24 nurseries (Table 1). Seventeen
of these were identified to species; the other five could be identified only to genus
because of poor specimen condition or inability to fit the description of North American
species.
Ten of the identified species (** in Table 1) were recorded in British Columbia for the
first time. The list contains many common species, but did not include members of the
Onychiuridae nor five species reported by Beirne (1972) to cause damage in agricultural
crops. Sminthurinus quadrimaculatus was the most frequently encountered species,
occurring in 13 of the nurseries surveyed. The next most frequently encountered species,
Willowsia buski, is ahousehold pest (Scott 1954). These species, however, are not known
to attack living plants.
Two recognized plant pests, Bourletiella hortensis and Isotomurus palustris, were
also encountered. B. hortensis is regarded as cosmopolitan (Salmon 1964). In Canada, it
has been reported from Nova Scotia, Quebec, Ontario, Manitoba and British Columbia
(Christiansen and Bellinger 1980). It appears to be an indiscriminate feeder (Marshall
1978) and causes damage to many agricultural crops (Edwards and Heath 1964; Beirne
1972). It also feeds on seedlings of larch, pine, and Engelmann, Sitka and white spruce
and western hemlock in bareroot nurseries (Bevan 1965; Marshall and IInytzky 1976). No
damage has yet been reported in container nurseries (Sutherland et al. 1989).
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 87
Table 1
Collembola and Acari from British Columbia forest nurseries.
COLLEMBOLA
BRACHYSTOMELLIDAE
Brachystomella parvula (Schaffer) ** GC *
Brachystomella stachi Mills ** GC
ENTOMOBRYIDAE
Entomobrya sp. CN, CR, NU, TH
Lepidocyrtus sp. NO
Lepidocyrtus sp.? bipunctatus Packard ** (a) MB
Orchesella zebra Guthrie ** GC
Willowsia buski (Lubbock) HN, HY, IE MB, NO, RC, SU, SY, TH
Willowsia sp. CR, HY
HYPOGASTRURIDAE
Hypogastrura matura (Folsom) ** RR, TE
Hypogastrura trybomi (Schott) ** HY
ISOTOMIDAE
Isotoma viridis Bourlet GC
Parisotoma notabilis (Schaffer) (b) GC
Isotoma sp. RC
Isotomurus palustris (Miiller) GB, KN
Proistoma immersa (Folsom) ** GC
NEANURIDAE
Morulodes serratus (Folsom) (c) CN
Pseudachorutes sp. NU
SMINTHURIDAE
Bourletiella hortensis (Fitch) EG, GB, HY, KN, NO, RC, SU, WN
Bourletiella sp. IK KN, WN
Eusminthurus sminthurinus (Mills) ** (d) HY
Sminthurinus quadrimaculatus (Ryder) ** CN, CR, CE EG, HE, HN, HY, IK NO, RC, SK, SY, WN
Sphaeridia pumilis (Krausbauer) ** (e) KN
ACARI
BDELLIDAE
Bdellodes sp. nr. bisetosa Atyeo AG, HY, RC
ERYTHRAEIDAE
? Erythrites sp. WN
EUPODIDAE
Eupodes voxencollinus Thor EG, MB, NU, SU, VN
PENTHALODIDAE
Penthalodes turneri Baker KN
* Abbreviations, location and sampling dates of the 24 nurseries follow, with (BRR) standing for Bareroot
and (CON) for Container nursery: 1. AG, Arbutus Grove, Sidney (CON) 88.06.08; 2. CN, Campbell River,
Campbell River (CON) 87.11.01 and 88.08.26; 3. CR, Chilliwack River, Chilliwack (CON) 88.06.03; 4.
CE Crown Forest, Armstrong (CON) 88.06.15; 5. EG, Elmore Greenhouses, Nanoose (CON) 88.06.06; 6.
GB, Green Timbers, Surrey (BRR) 71.05.19; 7. GC, Green Timbers, Surrey (CON) 87.11.24; 8. HE,
Hammer Enterprises, Maple Ridge (CON) 88.04.27; 9. HN, Harrop, Nelson (CON) 88.06.18; 10. HY,
Hybrid, Pitt Meadows (CON) 88.04.27 and 88.05.03; 11. IF Industrial Forest Service, Prince George
(CON) 88.06.21; 12. KN, Koksilah Canada, Duncan (BRR) 72.08.21; 13. MB, MacMillan Bloedel,
Nanaimo (CON) 88.06.09 and 88.08.25; 14. NO, Northwood, Prince George (CON) 88.06.21; 15. NU,
Nuu-chah-nulth, Port Alberni (CON) 88.06.09; 16. RR, Red Rock, Prince George (CON) 87.09.12; 17.
RC, Reid Collins, Aldergrove (CON) 88.05.30; 18. SK, Skimikin, Tappen (CON) 88.10.04; 19. SU,
Summit, Telkwa (CON) 88.06.23; 20. SY, Sylvan Vale, Black Creek (CON) 88.06.09; 21. TE, Telkwa,
Telkwa (BRR) 71.10.12; 22. TH, Thornhill, Terrace (CON) 88.06.23; 23. VN, Vernon, Vernon (CON)
88.06.15; 24. WN, Woodmere, Smithers (CON) 88.06.23.
** Newly recorded in British Columbia.
(a) Listed in subgenus Seira by Christiansen and Bellinger (1980).
(b) Listed in the genus Jsotoma by Christiansen and Bellinger (1980).
(c) Salmon (1964) listed this in the genus Lathriopyga, but more recent authors place it in Morulodes (Massoud
1967; Christiansen and Bellinger 1980; Fjellberg 1985).
(d), (e) Listed in the genera Sminthurinus and Sminthurides, respectively, by Christiansen and Bellinger
(1980).
88 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
Isotomurus palustris is common in Europe and is probably cosmopolitan (Salmon
1964). In Canada, it has been recorded from the Arctic, Ontario and British Columbia
(Salmon 1964). This species also appears to be an indiscriminate feeder and has attacked
sugar beets, sugar cane and tobacco (Scott 1954; Paclt 1956).
Only a few numbers of species were collected in most nurseries, with the highest
number of six species being present at Hybrid nurseries. No Collembola were collected at
Arbutus Grove and Vernon nurseries. Failure to obtain specimens at these two nurseries
is undoubtedly due to collection methods rather than a complete absence of Collembola.
Except for Campbell River, Hybrid and MacMillan Bloedel nurseries, which were
sampled twice, all other nurseries were sampled only once (Table 1). This limited
sampling and omission of soil in styroblocks and other habitats on nursery floors were
inadequate to give a representation of the entire collembolan fauna.
Both container and bareroot nurseries provide conditions that are conducive to the
establishment and maintenance of numerous species of Collembola. Such conditions
include high relative humidity, temperatures well within ranges tolerated by Collembola,
and plentiful food in the form of pollen and decomposing organic matter. Therefore, the
22 species collected probably represents less than half of the total number of species
present, considering the known distribution of North American Collembola (Chris-
tiansen and Bellinger 1980).
Although pest species are of special concern in nurseries, free-living Collembola
could be beneficial in two important ways. Firstly, Collembola may aid in the reduction of
inoculum of fungal diseases. Many species of Collembola consume fungi as a major
component of their diet (Takeda and Ichimura 1983). Onychiurus encarpatus Denis and
Proisotoma minuta (Tullberg), which occur throughout North America and are voracious
feeders on some fungi, are being investigated as potential control agents for Rhizoctonia
solani Kiihn, a pathogen of cotton seedlings (Curl et al. 1988; Lartey et al. 1989) and
other crops. Secondly, predators such as /. viridis might be helping to control phy-
tophagous Collembola.
While no special attempt was made to sample mites (Acari), four actinedid species
(Bdellodes sp. nr. bisetosa Atyeo, ?Erythrites sp., Eupodes voxencollinus Thor and
Penthalodes turneri Baker) were found among the Collemboia (Table 1). Only E.
voxencollinus was represented in many nurseries. E. voxencollinus and P. turneri are not
known to feed on Collembola, although they are in families considered general predators
(Krantz 1978). However, species in Bdellodes and Erythrites are potential natural control
agents for Collembola (Hoy et al. 1983).
It is only under exceptional conditions of high populations and lack of alternative food
supply are Collembolan pest species expected to sufficiently damage germinating
seedlings to make chemical or other control necessary (Edwards 1962, Christiansen
1964). Since damage has not yet been reported in container nurseries, collembolan pests
are apparently kept from reaching high numbers by competition with free-living
collembolan species and by the presence of predators. Mites are considered to be the
major predator controlling collembolan populations (Wallwork 1970). The sampling
technique used in this study cannot give information on collembolan populations and
their fluctuations relative to such predators. Therefore, further studies are required in
order to determine the effect of collembolan species on germinating conifer seedlings
and to determine when control measures would be warranted in British Columbian
nurseries.
J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 89
REFERENCES
Beirne, B.P. 1972. Pest insects of annual crop plants in Canada. Part IV. Other groups (Hymenoptera,
Dermaptera, Thysanoptera and Collembola); and Acarina and Symphyla. Mem. Entomol. Soc. Can.
85:58-73.
Bevan, D. 1965. Bourletiella signata (Nicol.) (Collembola)—a pest of conifer seedlings. Proc. XIIth Int.
Congr. Entomol. London. pp. 666-668.
Christiansen, K. 1964. Bionomics of Collembola. Ann. Rev. Entomol. 9:147-178.
Christiansen, K. and P. Bellinger. 1980. The Collembola of North America North of the Rio Grande; A
Taxonomic Analysis. Parts I-IV. Grinnell College, Iowa. 1322 pp.
Curl, E.A., R. Lartey and C.M. Peterson. 1988. Interactions between root pathogens and soil micro-
arthropods. pp. 249-261. In C.A. Edwards, B.R. Stinner, D. Stinner and S. Rabatin (eds.), Biological
Interactions in Soil. Elsevier, Amsterdam. vi + 380 pp. [Also in Agriculture, Ecosystems and Environ-
ment 24:249-261 (1988)].
Danks, H.V. 1988. Insects of Canada. Biological Survey of Canada Doc. ser. no. 1. 18 pp.
Edwards, C.A. 1962. Springtail damage to bean seedlings. Plant Pathol. 11(2):67-68.
Edwards, C.A. and G.W. Heath. 1964. The principles of agricultural entomology. Chapman and Hall Ltd.,
London. 418 pp.
Fjellberg, A. 1985. Arctic Collembola I— Alaskan Collembola of the families Poduridae, Hypogastruridae,
Odontellidae, Brachystomellidae and Neanuridae. Entomol. Scand. [1984] Suppl. 21:1-126.
Hoy, M.A., G.L. Cunningham and L. Knutson (eds.). 1983. Biological Control of pests by mites. Agr. Exp.
Sta., Div. Agr. Nat. Res., Univ. Calif., Berkeley, Special Pub. 3304. vii + 185 pp.
Kevan, D. K. McE. 1980. Students’ guide to the recognition of the families of the class Collembola
(Arthropoda: Hexapoda). Notes Lyman Entomol. Mus. Res. Lab. No. 7. 10 pp.
Krantz, G. W. 1978. A manual of Acarology. 2nd Edition. Oregon Sta. Univ. Book Store, Inc. Corvallis. viii +
509 pp.
Lartey, R.T., E.A. Curl, C.M. Peterson and J.D. Harper. 1989. Mycophagous grazing and food preference of
Proisotoma minuta (Collembola: Isotomidae) and Onychiurus encarpatus (Collembola: Onychiuridae).
Environ. Entomol. 18:334—337.
Marshall, V.G. and S. Ilnytzky. 1976. Evaluation of chemically controlling the collembolan Bourletiella
hortensis on germinating Sitka Spruce and Western Hemlock in the nursery. Can. J. For. Res. 6:467-474.
Marshall, V.G. 1978. Gut content analysis of the collembolan Bourletiella hortensis (Fitch) from a forest
nursery. Rev. Ecol. Biol. Sol. 15:243-250.
Massoud, Z. 1967. Monographie des Neanuridae, collemboles poduromorphes a piéces buccales modifiées. pp.
7-399. In C. Delamare Deboutteville and E. Rapoport (eds.), Biologie de L’Amérique Australe. Vol. III:
Etude sur la faune du sol; Documents biogéographiques. CNRS, Paris. 725 pp.
Paclt, J. 1956. Biologie der primar fliigellosen Insekten. Gustav Fischer Verlag, Jena. vii + 258 pp.
Richards, W.R. 1979. Collembola. pp. 300-303. In H.V. Danks (ed.) Canada and its insect fauna. Mem.
Entomol. Soc. Can. 18. 573 pp.
Rusek, J. 1974. Die Préparation von Kleininsekten. Mikrokosmos, January 1974 (1):10-12.
Salmon, J.T. 1964. An index to the Collembola (Vols. 1-3). R. Soc. N. Z., Bull 7. 651 pp.
Scott, D.B. 1954. The economic biology of Collembola. J. Econ. Entomol. 46(6):1048-1051.
Scudder, G.G.E., D.K.McE. Kevan and E.L Bousfield. 1979. Higher classification. pp 235-240. In H.V.
Danks (ed.) Canada and its insect fauna. Mem. Entomol. Soc. Can. 18. 573 pp.
Spencer, G.J. 1959. On mounting lice by the Ris Lambers method for aphids. Entomol. Soc. Brit. Columbia
56(4):53.
Sutherland, J.R., G.M. Shrimpton and R.N. Sturrock. 1989. Diseases and insects in British Columbia forest
seedling nurseries. FRDA report 065, Forestry Canada and British Columbia Ministry of Forests. vi + 85
Pp.
Takeda, H. and T. Ichimura. 1983. Feeding attributes of four species of Collembola in a pine forest soil.
Pedobiologia 25:373-381.
Wallwork, J.A. 1970. Ecology of soil animals. McGraw-Hill, Toronto. xiii + 283 pp.
90 J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990
ERRATA
Editor’s Note
These extensive errata were caused by the combined failure of the printer to make the
corrections noted by the author on the galley proofs and the editor for not picking up the
mistake. I apologize to the author for any embarrassment that may have resulted.
Santiago-Blay, J.A. 1989. Chalcidoids (Hymenoptera) reared from Artemisia tridentata
(Asteraceae) galls from British Columbia, Canada. J. Entomol. Soc. Brit. Columbia
86:80-81.
Page 80
Line 2: “GALLS IN” should read “GALLS FROM”
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Line 11: “22 June” should be “11 July”
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Page 81
Lines 1, 2: “widths to it (= width)” should read “widths”
Line 3: “9-18 ...7-12” should read “9-18 mm... 7—12 mm”
Line 4: “collection; which” should read “ collection which”
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males... females, three”
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diameter”
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four to seven.” “Eupelmus (Eupelmidae)”.
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J. ENTOMOL. Soc. BRIT. COLUMBIA 87, DECEMBER, 1990 91
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Journal
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Volume 87 Issued December 1990 ISSN #0071-0733
Directors of the Entomological Society of British Columbia, 1990-91
Dang, PT. and D.J. Parker. First Records of Enarmonia formosana (Scopoli) in
North America (Lepidoptera: Tortricidae)
Wigle, M.J. and H.V. Thommasen. Ephemeroptera of the Bella Coola and
Owikeno Lake watersheds, British Columbia Central Coast
Heath, R. and R.I. Alfaro. Growth response in a Douglas fir/lodgepole pine stand after
thinning of lodgepole pine by the mountain pine beetle: A case study
Harris, L.J., R.I. Alfaro and J.H. Borden. Role of needles in close-range host selection
by the white pine weevil on Sitka spruce
Sheppard, D.H., J.H. Myers, S. Fitzpatrick and H. Gerber. Efficacy of deltamethrin and
Bacillus thuringiensis Berliner spp. kurstaki on larvae of winter moth, Operophtera
brumata (L.) (Lepidoptera: Geometridae) attacking blueberry in the Lower
Mainland of British Columbia
Shore, T.-L. Recommendations for sampling and extracting the eggs of the western
hemlock looper, Lambdina fiscellaria lugubrosa, (Lepidoptera: Geometridae)
Belton, E.M. and P. Belton. A review of mosquito collecting in the Yukon
Vernon, R.S. and D.R. Gillespie. Response of Frankliniella occidentalis (Thysanoptera:
Thripidae) and Trialeurodes vaporariorum (Homoptera: Aleyrodidae) to fluorescent
traps in a cucumber greenhouse
Michaud, J.P Observations on the biology of the bronze flea beetle Altica tombacina
(Coleoptera: Chrysomelidae) in British Columbia
Frazer, B.D. and R.R. McGregor. A rapid method of sampling for aphids on
strawberries
Mohammad, A.B. and M.T. AliNiazee. Toxicity of foliar residues of phosmet to the
apple maggot, Rhagoletis pomonella (Diptera: Tephritidae)
Raworth, D.A. Predators associated with the twospotted spider mite, Tetranychus urticae,
on strawberry at Abbotsford, B.C., and development of non-chemical mite control... .59
Kovacs, E. and J.A. McLean. Notes on the longevity, fecundity and development of .
Pissodes terminalis Hopping (Coleoptera: Curculionidae) in the Interior of British
Columbia, Canada
Gerber, H.S. Note on the occurrence of Paravespula germanica (Hymenoptera: Vespidae)
in the Lower Fraser Valley of British Columbia
Kovacs, E. and J.A. McLean. Emergence patterns of terminal weevils (Coleoptera:
Curculionidae) and their parasitoids from lodgepole pine in the Interior of British
Columbia, Canada
Roland, J. and S. Szeto. Compatibility of the winter moth parasitoid Cyzenis albicans
(Tachinidae) with pesticide use in the cultivation of blueberries in the Fraser Valley . . .79
Cossentine, J.E., FL. Banham and L.B. Jensen. Efficacy of the nematode, Heterorhabditis
heliothidis (Rhabditida: Heterorhabditidae) against the peachtree borer, Synanthedon
exitiosa (Lepidoptera: Sesiidae) in peach trees
Marshall, V.G., G.M. Shrimpton and J.P. Battigelli. A preliminary survey of Collembola
in forest nurseries of British Columbia
Journal
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Volume 88 Issued December 1991 ISSN #0071-0733
Entomological Society
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COVER: An adult female Hyalophora euryalus kasloensis (Cockerell) (Lepidoptera:
Saturniidae) drawn with pen and ink by Sheri Giesbrecht from specimens reared by Dean
Morewood. The ceanothus silkmoth, Hyalophora euryalus (Boisduval), is native to the
Pacific coast and western mountains of North America from Baja California to British
Columbia. Despite any nominal preference for ceanothus, larvae of this species have been
reported to feed on a wide variety of broad-leaved trees and shrubs and at least one
conifer. In mid to late summer the larvae spin sturdy tear-drop shaped cocoons, usually
attached at the side to twigs of their host plant, within which they spin a second cocoon.
After overwintering as diapausing pupae, the large reddish brown moths emerge from
their cocoons mainly in May and June, and dedicate their one week adult lifespan to repro-
duction. The form known as H. e. kasloensis is found in the interior of B.C. and northern
Washington and Idaho and shows a distinct larval phenotype, but its taxonomic status has
yet to be firmly established (see p. 31).
Designed, typeset and printed by
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J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
Journal
of the
Entomological Society
of British Columbia
Volume 88 Issued December 1991 ISSN #007 1-0733
Directors of the Entomological Society of British Columbia, 1991-92 ooo eeeeneteeeees 2
Taylor, S., R.I. Alfaro and Kornelia Lewis. Factors affecting the incidence
of white pine weevil damage to white spruce in the Prince George Region
MRED GL Tee MUU Dl sneer cs icy canto spsec eae nessa asl era eg a jintrip lea aad eons eer de cpa sessanrtersn eaten eanecenasanee 3
Forbes, A.R. and C.K Chan. The Aphids (Homoptera: Aphididae)
Ga butishC olumbia 20) Further addons civic cess siccusssveseiees soos ecortnepuoedeieivsselucdanatieldseesecoeuts 7
Mayer, D.F. and J.D. Lunden. Honey bee foraging on dandelion and
CL eet ecu ORCI AL CS) areca uct ands vvesanutrs sisatactesecs secbnssimsmsticcce soetstensounes suniuissanenddeaatecindeemaee: [5
Safranyik, L. and D.A. Linton. Unseasonably low fall and winter temperatures
affecting mountain pine beetle and pine engraver beetle populations and
damave in the British Columbia Chilcotin ReGi0N «...:..2...cc0.cc00-0cccsesornnasenscenavacacessvoncnecese 17
Toba, H.H. and J.F. Howell. An improved system for mass-rearing
OCI TN 8, CINCO) TSA cE Sb eo rE eet ee eee re 22
MacCarthy, H.R. Compound eye of male Stylops pacifica
US Gie@ Siete SEV ODICAC)) sn. ice tie sia cette aera se nreqeein gues, catdussitedaqaeinahearGieatuaneey wan tteaadenerd yal
Morewood, W.D. Larvae of Hyalophora euryalus kasloensis
CIES MiG ta 7S ALUGIMLIGAS) sssadesaccer-cccstrevdousesasusudesstheesayceede.daveccecukasvscetasmed esau annua viens «anes 3]
Miller, Daniel R. and Jean P. Lafontaine. cis-Verbenol: An aggregation
pheromone for the mountain pine beetle, Dendroctonus ponderosae
opkans(G ole@ptena-Scoly Gdae). si-c.5- cece... cecaeeessaseas tees neneset soa cvenndennescecenedevneeiaaeiiacateenes 34
Fitzpatrick, Sheila M. and James T. Troubridge. Melanchra picta (Harris)
(Lepidoptera: Noctuidae), a cutworm new to British Columbia ...............ccccscccceeessseeeees 38
Fitzpatrick, Sheila M., James T. Troubridge and Barbara Peterson. Distribution
of European winter moth, Operophtera brumata (L.), and Bruce spanworm,
O. bruceata (Hulst), in the lower Fraser Valley, British Columbia ..................ccccceeseeeee dD
Fontaine, A.R., N. Olsen, R.A. Ring and C. L. Singla. Cuticular metal hardening
of mouthparts and claws of some forest insects of British Columbia................ccccceeeees 45
NO AIGE TO CONTRIB TORS fonio.ceceatastascaeavetsdyiasthooensocivcssheniativeotoneieusedéonevoscetnaceascasadnns 56
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
DIRECTORS OF THE ENTOMOLOGICAL SOCIETY
OF BRITISH COLUMBIA FOR 1991-92
President
Bob Vernon
Agriculture Canada, Vancouver
President-Elect
Terry Shore
PFC, Victoria
Past-President
Joan Cossentine
Agriculture Canada, Summerland
Secretary-Treasurer
Hilary Graham
Agriculture Canada, Summerland
Editorial Committee (Journal)
R. Ring (Editor) H.R. MacCarthy D.Raworth
Editor (Boreus)
Imre Otvos
PFC, Victoria
Directors
T. Danyk (2nd) G. Judd (2nd) J. Troubridge (2nd)
T. Lowery (ist) D. Morewood (ist)
Honorary Auditor
Chris Guppy
Regional Director of National Society
Bob Vernon
Agriculture Canada, Vancouver
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 3
Factors affecting the incidence of white pine weevil damage
to white spruce in the Prince George Region
of British Columbia
S. TAYLOR], R.I. ALFARO? and KORNELIA LEWIS?
1. PRINCE GEORGE FOREST REGION
BRITISH COLUMBIA MINISTRY OF FORESTS
PRINCE GEORGE, BRITISH COLUMBIA, CANADA
2. FORESTRY CANADA, PACIFIC FORESTRY CENTRE
VICTORIA, BRITISH COLUMBIA, CANADA V8Z 1M5
3. UNIVERSITY OF VICTORIA, DEPT. OF BIOLOGICAL SCIENCES
VICTORIA, BRITISH COLUMBIA, CANADA
ABSTRACT
A survey was conducted to study the incidence of attack by the white pine weevil, Pissodes
strobi (Peck) on white spruce, Picea glauca (Moench) Voss., in the Prince George Region of
British Columbia, in relation to biogeoclimatic subzone, site quality class and plantation age.
The average percentage attack on the spruce component was 3.2% (range 0 to 26.6%). A
general trend of increasing attack with increasing biogeoclimatic subzone moisture was
found. No correlation was found between percentage attack and site quality or age. The
implications of this survey for the Prince George Region are discussed.
INTRODUCTION
In British Columbia, the white pine weevil, Pissodes strobi (Peck) (Coleoptera;
Curculionidae), causes serious damage to Sitka spruce, Picea sitchensis (Bong) Carr.,
white spruce, Picea glauca (Moench) Voss., and Engelmann spruce, Picea engelmannii
Parry ex Engelm. (Alfaro 1982, Cozens 1983, McMullen 1976, McMullen and
Condrashoff 1973, Stevenson 1967). Adult weevils overwinter in the duff and emerge in
the spring to oviposit in year-old spruce leaders (Wood and McMullen 1971). Within
about 10 days, the eggs hatch and the larvae begin to mine downward feeding on the
phloem. The year-old leader is eventually killed through girdling which results in height
growth loss. Greater losses occur if larvae mine past the year-old leader into the previous
year’s growth or if re-attack occurs below an attacked leader (Cozens 1987). Most adults
emerge in late summer and fall, and, after feeding for a while, go to their overwintering
sites. Depending on local climate, a portion of the larval population remains to overwinter
within the leaders. Attacked trees usually develop stem defects (Alfaro 1989a) which
affect the value of the logs obtained from the trees. Repeated attacks produce stunted and
deformed trees.
McMullen (1976) studied the ecological factors which affect the distribution of P.
strobi on Vancouver Island. Based on the minimum requirement for accumulated heat
needed for brood development, McMullen concluded that low weevil hazard zones would
occur on Northern Vancouver Island and along its extreme Western coastline. These find-
ings were confirmed by Heppner and Wood (1984) who examined Sitka spruce planta-
tions within the coastal Vancouver Forest Region of B.C., and concluded that these low
hazard zones coincide closely with the Southern Hypermaritime Coastal Western
Hemlock Biogeoclimatic Subzone Variant CWHvh. Past incidence surveys in the interior
of B.C. (Lewis 1988) have yielded some results, but have never been stratified by biogeo-
climatic units. This is important because ecological factors may influence the susceptibil-
ity of stands to weevil attack. In this study we report the results of a survey conducted in
the Prince George Forest Region of B.C. to determine the incidence of P. strobi damage
in white spruce in relation to biogeoclimatic zone, site quality and plantation age.
4 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
. 0 FORT ST. JAMES
e of
PRINCE
GEORGE
Figure |. Location of the spruce plantations surveyed for Pissodes strobi incidence in the Prince
George, Vanderhoof and Fort St. James Forest Districts, of the Prince George Timber Supply Area,
in the Prince George Forest Region of British Columbia.
METHODS
Plantation selection
The survey was conducted in the Prince George Timber Supply Area (T.S.A.) of the
Prince George Forest Region, which includes the Prince George, Vanderhoof and Fort St.
James Forest Districts. A computer printout list of all second growth spruce plantations
established in the T.S.A. since the 1960’s was obtained from the B.C. Ministry of Forests
Silviculture Branch. The plantation list included, among other attributes, the establish-
ment date, site quality classification, and the biogeoclimatic zone and subzone of each
plantation. Only plantations in which spruce was the dominant species and only those in
the Sub-Boreal Spruce (SBS) biogeoclimatic zone (predominant in the Prince George
T.S.A) were considered for examination of white pine weevil damage. The plantations
were stratified based on biogeoclimatic subzone into groups which differed in soil mois-
ture availability (Meidinger in press) as follows: DRY which included subzones dk, dw7
and dw3; MOIST, including subzones mw, mc9, and mk1; and WET including subzones
vk and wk1. The plantations were further stratified by site quality classification into good
and medium sites, and by plantation age into three classes: 11-15, 16-20 and 21-25 years
old.
Plantations which did not fall into one of these classes, were not considered in the
study. No plantations were located in the SBS dry/good site 21-25 age class. Therefore,
only 17 different categories were surveyed. The total number of plantations which fell
into each category ranged from 1 to 200. In the categories which contained more than five
plantations, five were randomly selected to be surveyed. If the category had five planta-
tions or less, all plantations in that class were chosen. In all, 58 plantations were surveyed
(Fig.1)):
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 5
Each plantation was identified on a 1:15,840 scale forest cover map provided by the
forest district and on aerial photos. To estimate the percentage of P. strobi attack in a
plantation, we used the systematic strip sampling method recommended by Fletcher
(1986), who concluded that reasonably accurate estimates of weevil incidence could be
obtained from sampling as few as five strips per plantation. In each plantation, a point of
origin was established at random along the perimeter of the plantation. Then, starting at
this point, five strips of equal length were established. The strips usually ran the approxi-
mate width of the plantation and were evenly spaced so that maximum coverage of the
plantation was achieved. The length of each strip was determined using a topofil measur-
ing meter. All planted spruce trees within 5.0 m of either side of the strip were examined
for 1988 white pine weevil attack. Also recorded was the number of trees from species
other than spruce which occurred as ingrowth on the plantation. For each plantation the
percentage of spruce trees attacked was calculated with respect to the total number of
trees and with respect to the spruce component.
The data were subjected to analysis of variance/covariance to test for significant differ-
ences in the percentage of white spruce trees attacked based on biogeoclimatic subzone,
site quality and age. Stand density was used as a covariate. Attack percentages were trans-
formed by the arcsin transformation before the analysis. The ANOVA procedures for
unequal. numbers of samples were used. Means were separated using the Student
Newman-Keuls test.
RESULTS
The mean percent attack in the spruce component over all plantations was 3.2% (range 0
to 26.6%). The percentage spruce attacked with respect to all the trees in a stand averaged
2.5% (range of 0 to 23.7%) over all plantations.
The percentages of the spruce component attacked were sorted into 5% attack classes
(Table 1). Nine of the 58 plots surveyed, or 15.5%, were free from weevil attack. Most
plots (65.5%) had attack percentages of 0.1 to 5% (38% had 0.1 to 1% attack).
Approximately 10 and 5% of the plots had attack intensities in the 5.1 to 10 and 10.1 to
15% classes, respectively. Only 2 plots (3.4%) had attack intensities higher than 15%.
A general trend to increasing attack with increasing site moisture (biogeoclimatic sub-
zone class) was detected for both the percentage attack on the spruce component and the
percentage attack on the total stand (Table 2). This relationship, however, was statistical-
ly significant only when percentage attack was calculated as a proportion of all trees in
the plantation (ANOVA, F = 4.5, P <0.05). The percentage of the spruce attacked was
nearly three times higher on the Wet than on the Dry sites; similarly, the percentage of all
plantation trees attacked was nearly 10 times higher on Wet than on Dry sites (Table 2).
None of the other variables tested (site quality, plantation age or plantation density) had a
significant relationship with the percentage of spruce trees attacked. This was true for the
percentage calculated in relation to the spruce component or for the total number of trees
in the stand.
DISCUSSION
Most reports of P. strobi damage come from the Sitka spruce literature where incidences
of more than 50% trees attacked/year have been reported (Alfaro and Omule 1990). The
incidence of P. strobi in the Prince George T.S.A. was generally low. However, the fact
that individual plantations in this study had attack intensities as high as 26.6% indicates
that white spruce is also highly susceptible to attack. The generally low incidence is prob-
ably due to the fact that most plantations in the Prince George area are young and are just
entering their most susceptible stage. However, the lack of correlation of attack intensity
with age may appear to contradict this statement. If plantations are more susceptible as
they get older, a positive correlation of the attack with age was expected. The low correla-
tion with age could be due to the fact that the older plantations are rare in this Region and
6 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
Table 1
Plantations surveyed in the Prince George Timber Supply Area
tabulated by percentage attack by P. strobi.
Percentage* No. of Percentage of
attack class plantations plantations
0 9 Itt)
0.1- 5 38 65.5
5.1-10 6 10.3
10.1-15 3 5:3
15.1-20 0 0.0
20.1-25 1 gl
25.1-30 | jew!
ok .
Percentage attack on the spruce component of the plantations.
Table 2
Mean percentage attack by P. strobi in 58 spruce plantations surveyed in the Prince George
Forest Region, tabulated by moisture code, site and age class.
Extent of total
Spruce trees attacked plantation attacked
No. of Standard Standard
Code/Class plantations % Deviation % Deviation
Moisture
Dry 13 1.7a a9 0.4ab 0.6
Moist 19 2.5a 4.1 2.0bc ee
Wet 26 4.6a 6.8 3.8¢ 5.9
Site
Medium 31 3.4a 6.4 2.6a 36
Good ZF ala Se pasey} 363
Age
11-15 yrs 25 3.0a 53/7 23a 53
16-20 yrs 19 4.4a ~ 6.3 3.38 Dal
21-25 yrs 14 2.la 2.9 1.6a Doe)
Means followed by the same letter were not statistically different
(ANOVA and Student Newman-Keuls test P>0.05).
have until now escaped attack. Late invasion of older plantations after the weevil popula-
tion reaches epidemic levels has been observed in the field by the authors. Whether interi-
or spruce will ever show the elevated levels of attack reported for Sitka spruce (Alfaro
1982, Alfaro and Omule 1990) remains to be seen.
The high incidence of weevil damage in the wet habitats is probably due to fast growth
in the spruces in response to high available moisture which produce long leaders and so
favour weevil survival. In coastal Sitka spruce, P. strobi prefers to attack the trees with
the longest leaders (Alfaro 1989b).
The results of this survey indicate that the white pine weevil has a generally low inci-
dence in this Region and that, because a potential for higher populations does exist,
foresters should continue to monitor this problem.
ACKNOWLEDGMENTS
This study was partially funded through FRDA (Forest Resource Development
Agreement). Our thanks are also extended to E. Wegwitz and D. Eyres for technical assis-
tance.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 7
REFERENCES
Alfaro, R.I. 1982. Fifty-year-old Sitka spruce plantations with a history of intense weevil attack. J. Entomol.
Soc. Brit. Columbia 79: 62-65.
Alfaro, R.I. 1989a. Stem defects in Sitka spruce induced by Sitka spruce weevil, Pissodes strobi (Peck.), Pp.
177-185 in Alfaro, R.I. and S. Glover (editors). Insects affecting reforestation: biology and damage.
Proceedings of a IUFRO symposium held on July 3-9, 1988, in Vancouver, B.C. Canada, under the auspices
of the X VIII International Congress of Entomology. Forestry Canada, Victoria, B.C.
Alfaro, R.I. 1989b. Probability of damage to Sitka spruce by the Sitka spruce weevil, Pissodes strobi (Peck). J.
Ent. Soc. Brit. Columbia 86: 48-54.
Alfaro, R.I. and S.A.Y. Omule. 1990. The effects of spacing on Sitka spruce weevil damage to Sitka spruce.
Can. J. For. Res. 20: 179-184.
Cozens, R.D. 1983. The spruce weevil, Pissodes strobi Peck, (Coleoptera: Curculionidae). A review of its biol-
ogy, damage and control techniques with reference to the Prince George Timber Supply Area. B.C. Min of
For. Int. Rep. PM-PG-3.
Cozens, R.D. 1987. Second broods of Pissodes strobi (Coleoptera: Curculionidae) in previously attacked leaders
of interior spruce. J. Entomol. Soc. Brit. Columbia 84: 46-49.
Fletcher, V.E. 1986. Development of sampling guidelines for estimating the proportion of weeviled trees on a
plantation. B.C. Min. of For. Int. Rep. PM-PB-18.
Heppner, D.G. and P.M. Wood. 1984. Vancouver Region Sitka spruce weevil survey results (1982-1983), with
recommendations for planting Sitka spruce, B.C. Min. of For. Int. Rep. PM-V-5.
Lewis, K.G. 1988. Spruce weevil in spruce plantations in the Cariboo Forest Region B.C. Min. of For. Cariboo
For. Reg. Williams Lake, B.C. Unpublished report. 35 pp.
Meidinger, D., J. Pojar and W.L. Harper. In press. Sub-boreal spruce zone. In D. Meidinger, and J. Pojar (eds.),
“Ecology of British Columbia”. B.C. Min. of Forests, Special Report Series.
McMullen, L.H. 1976. Spruce weevil damage. Ecological basis and hazard rating for Vancouver Island. Can.
For. Serv. Pac. For. Res. Cent. Inf. Rep. BC-X-141. Victoria, B.C. 7p.
McMullen, L.H. and S.F. Condrashoff. 1973. Notes on dispersal, longevity and overwintering of adult Pissodes
strobi (Peck) (Coleoptera: Curculionidae) on Vancouver Island. J. Entomol. Soc. Brit. Columbia 70: 22-26.
Stevenson, R.E. 1967. Notes on the biology of the Engelmann spruce weevil, Pissodes engelmanni
(Curculionidae: Coleoptera) and its parasites and predators. Can. Entomol. 99: 201-213.
Wood, R.O. and L.H. McMullen. 1971. Spruce weevil in British Columbia. Can. Dept. For. Can. For. Ser. Pac.
For. Res. Cent. Pest Leaflet.
The Aphids (Homoptera: Aphididae) of British Columbia
20. Further additions
A.R. FORBES and C.K. CHAN
RESEARCH STATION, AGRICULTURE CANADA
VANCOUVER, BRITISH COLUMBIA, V6T 1X2
ABSTRACT
Five species are added to the aphid fauna of British Columbia. Fifty-four of the 88 new
aphid-host plant associations of plant species are new host plants.
INTRODUCTION
Four hundred species of aphids collected from 1124 hosts or in traps, and 2233 aphid-host
plant associations were recorded in fifteen previous lists of the aphids of British
Columbia (Forbes, Frazer and MacCarthy 1973; Forbes, Frazer and Chan 1974; Forbes
and Chan 1976, 1978, 1980, 1981, 1983, 1984, 1985, 1986a, 1986b, 1987, 1988, 1989;
Forbes, Chan and Foottit 1982). The present list adds 5 aphid species (indicated with an
asterisk in the list) and 88 aphid-host plant associations to the previous lists. Fifty-four of
the new aphid-host plant associations of plant species have not been recorded before. The
additions bring the number of known aphid species in British Columbia to 405. Aphids
have now been collected from 1178 different host plants and the total number of aphid-
host plant associations is 2321.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
Table 1
Collection sites of aphids, with airline distances from reference points
Locality
Allison Pass
Bijoux Falls
Blue River
Burns Bog
Castlegar
Cedarvale
Chemainus
Chetwynd
Christian Valley
Christina Lake
Cinema
Crowsnest Pass
Eighty-three Mile House
Greenwood
Heffley Creek
Hixon
Houston
Jaffray
Lakelse Lake
Long Beach
Lost Lake
Mayne Island
McLeese Lake
McLeod Lake
Moricetown
Mount Robson
Mount Robson
Provincial Park
Moyie Lake
Nakusp
Nanoose
Nechako
New Hazelton
Okanagan Lake Park
Pavilion
Rossland
Salmo
Saltspring Island
Silver Star Mountain
South Hazelton
Sparwood
Squilax
Stagleap Provincial Park
Taylor
Tete Jaune
Topley
Trinity Valley
Valemount
Whistler
Whistler Village
Widgeon Creek
Yahk
Reference Point
Kamloops
Prince George
Williams Lake
Vancouver
Creston
Prince Rupert
Victoria
Prince George
Creston
Creston
Prince George
Creston
Williams Lake
Creston
Kamloops
Prince George
Prince Rupert
Creston
Prince Rupert
Victoria
Vancouver
Victoria
Williams Lake
Prince George
Prince Rupert
Williams Lake
Williams Lake
Creston
Creston
Vancouver
Prince Rupert
Prince Rupert
Kelowna
Kamloops
Creston
Creston
Victoria
Kamloops
Prince Rupert
Creston
Kamloops
Creston
Prince George
Williams Lake
Prince Rupert
Kamloops
Williams Lake
Vancouver
Vancouver
Vancouver
Creston
km
Distance
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 9
The aphid names are in conformity with Eastop and Hille Ris Lambers (1976) and are
listed alphabetically by species, except that Aphis citricola van der Goot has been restored
to its former name, Aphis spiraecola Patch, based on the findings of Eastop and
Blackman (1988). Names of native host plants are based on Anonymous (1982) and
Taylor and MacBryde (1977). Names of cultivated host plants are based on Anonymous
(1976). Fifty-one new collection sites are given in Table 1. The reference points are the
same as those shown on the map which accompanies the basic list (Forbes, Frazer and
MacCarthy 1973). Most of the aphids were collected by the authors except the Cinara
spp. were Foottit’s (1987) collections.
LIST OF SPECIES
AGATHONICA Hottes 1950, AMPHOROPHORA
Rubus idaeus ‘Tulameen’: Abbotsford, Jul9/90.
ALBIFRONS Essig 1911, MACROSIPHUM
Lupinus ‘Russell Hybrid’: Pemberton, Aug9/90.
* AL NIFOLIAE SSP FITCHII Baker & Davidson 1917, PROCIPHILUS
Pinus contorta var latifolia: Whistler, Sep15/90.
ANNULATUS (Hartig 1841), TUBERCULATUS
Quercus robur: Vancouver (UBC), Oct16/90.
ANTIRRHINII (Macchiati 1883), MYZUS
Brassica juncea ‘Florida Broadleaf : Vancouver (CDA), May15/89.
Capsella bursa-pastoris: Vancouver, Jul1/89, Aug2/89.
Chlorophytum comosum ‘Variegatum’: Vancouver (CDA), Jul20/89.
Chlorophytum comosum ‘Vitatum’: Vancouver (CDA), Jun27/89.
Draba lindensii: Vancouver (UBC), Feb24/88.
Hoya carnosa: Vancouver (CDA), Dec14/89.
ASCALONICUS Doncaster 1946, MYZUS
Daucus carota: Vancouver (CDA), Jun7/89.
Senecio eremophilus var eremophilus: Vancouver (CDA), May 16/89.
AVELLANAE (Schrank 1801), COR YLOBIUM
Corylus cornuta var californica: Vancouver, May 15/90.
AVENAE (Fabricius 1775), SITOBION
Avena sativa ‘Clintland’: Abbotsford, Jun21/90.
Phleum pratense: Vancouver (CDA), Jul7/90.
BAKERI (Cowen 1895), NEARCTAPHIS
Crataegus viridis ‘Winter King’: Vancouver (UBC), Oct16/90.
BRASSICAE (Linnaeus 1758), BREVICOR YNE
Brassica oleracea ‘Purple Sprouting’: Vancouver (UBC), Nov27/90.
Brassica oleracea ‘White Sprouting Late’: Vancouver (UBC), Nov27/90.
[satis tinctoria: Vancouver (UBC), Aug8/89.
BREVISPINOSA (Gillette & Palmer 1924), CINARA
Pinus contorta: Allison Pass, Jul11/82; Beaverdell, Jul19/79; Bowser, Jul7/81; Burns
Lake, Aug1/80; Campbell River, Sep26/41 ; Cascade, May28/57; Castlegar,
Jull0/82 ; Cedarvale, Jun28/41; Christian Valley, Jun21/80; Cowichan Lake,
May25/56; Creston, Jul10/82; Eighty-three Mile House, Jul29/80 Heffley Creek,
Jun26/80; Hixon, Jul31/80; Houston, Aug4/80; Lac La Hache, Jul29/80; Long
Beach, May13/79; Mackenzie, Aug6/80; McLeod Lake, Aug5/80; Mount Robson
Provincial Park, Aug5/77 , Aug!2/80; Moyie Lake, Jull10/82 ; Nakusp, Jun22/80;
Nanaimo, May28/58, Jul7/81; Nechako, Jun4/59; New Hazelton, May22/41;
Parksville, Jul7/81; Pitt Meadows, Jun27/81; Prince George, Jul31/80, Aug5/80 ;
Princeton, Jun17/80, Jul1/81; Salmo, Jul10/82; Sayward, Jul8/81; Shuswap Lake,
Junl1/59; Sparwood, Jul9/82; Stagleap Provincial Park , Jull10/82; Terrace,
Aug3/80; Tofino, May26/62; Vernon, Jun16/56; Westbridge, Jun21/80, Jul27/77;
Yahk, Jul10/82 (all Foottit 1987).
10 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
CANADENSE (Robinson 1968), DELPHINIOBIUM
Lonicera involucrata: Lost Lake, Jun26/90.
CAPILANOENSE Robinson 1969, AULACORTHUM
Rubus spectabilis: Shannon Falls, Jun26/90.
CARAGANAE (Cholodkovsky 1907), ACYRTHOSIPHON
Caragana arborescens: Vancouver (UBC), Jul20/90.
CARNOSUM (Buckton 1876), MICROLOPHIUM
Urtica dioica: Peace Arch Park, Jul2/90.
CERASI (Fabricius 1775), MYZUS
Galium odoratum: Vancouver (UBC), May 16/89.
Prunus emarginata: Vancouver (UBC), Jul20/90.
CHANI Robinson 1985, UROLEUCON
Grindelia nana: Vancouver (UBC), Aug16/89.
CIRCUMFLEXUM (Buckton 1876), AULACORTHUM
Heliotropium arborescens: Vancouver (UBC), Aug20/89.
Pernettya mucronata ‘Coccinea’: Vancouver (UBC), Oct16/90.
*CONTORTAE Hottes 1958, CINARA
Pinus contorta: Bowser, Jul7/81; Burns Bog, Aug6/81 Oct2/81; Burns Lake, Aug4/80;
Castlegar, Jul10/82; Christian Valley, Jun21/80, Jull1/81; Christina Lake, Jul29/59;
Fraser Lake, Augl/80; Houston, Aug4/80; Jaffray, Jul9/82; Lumby, Jun12/59;
Mackenzie, Aug6/80; McLeese Lake, Jul29/80; Moricetown, Aug3/80 ; Moyie
Lake, Jull0/82; Nanaimo, Jul7/81; Pitt Meadows, Jun27/81, Aug7/81; Port
Coquitlam, Sep9/82, Oct11/82; Princeton, Jun17/80; Quesnel, Jul30/80, Jul3 1/80;
Silver Star Mountain, Jun16/59; South Hazelton, Aug3/80; Summit Lake, Aug5/80;
Terrace, Aug3/80; Westbridge, Jun21/80, Jul23/79 (all Foottit 1987).
CORYLI (Goeze 1778), MYZOCALLIS
Corylus cornuta: Vancouver (UBC), Oct24/88.
COWEN I (Cockerell 1905), TAMALIA
Arctostaphylos uva-ursi: Vancouver, Jul20/90.
CRYSTLEAE (Smith & Knowlton 1939), ILLINOIA
Lonicera involucrata: Cinema, Jul2/66.
CYPERI (Walker 1848), THRIPSAPHIS
Carex retrorsa: Vancouver (UBC), Aug25/89.
Scirpus americanus: Vancouver (UBC), Aug25/89.
DAPHNIDIS Borner 1950, MACROSIPHUM
Daphne laureola: Vancouver, Feb1/90; Vancouver (UBC), Nov22/89.
DIRHODUM (Walker 1849), METOPOLOPHIUM
Phleum pratense: Vancouver (CDA), Jul7/90.
Triticum x aestivum: Vancouver (CDA), Jun21/90.
ELEGANS del Guercio 1905, SIPHA
Triticum x aestivum: Creston, Nov28/88.
ERIOPHORI (Walker 1848), CERURAPHIS
Carex retrorsa: Vancouver (UBC), Aug25/89.
Catalpa speciosa: Vancouver, Oct25/88.
Viburnum carlesii: Vancouver, Jun2/88.
FABAE Scopoli 1763, APHIS
Dahlia sp: Victoria, Jul27/88.
Gleditsia triacanthos: Richmond, Jul14/88.
FAGI (Linnaeus 1767), PHYLLAPHIS 3
Fagus sylvatica: Vancouver (UBC), Nov22/89.
*FILIFOLIAE (Gillette & Palmer 1928), OBTUSICAUDA
Artemisia tridentata: Pavilion, May21/89.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
FIMBRIATA Richards 1959, FIMBRIAPHIS
Capsella bursa-pastoris: Vancouver (CDA), Oct15/89.
Rosa ‘Red Minimo’: Vancouver (CDA), Oct15/89.
Rosa ‘Rosy Minimo’: Vancouver (CDA), Oct15/89
FOENICULI (Passerini 1860), HY ADAPHIS
Lonicera tragophylla: Vancouver (UBC), Jul3/90, Sep13/89.
FRAGAEFOLII (Cockerell 1901), CHAETOSIPHON
Fragaria x ananassa ‘Totem’: Vancouver (UBC), Nov27/90.
FRAXINIFOLII (Riley 1879), PROCIPHILUS
Fraxinus excelsior: Vancouver (UBC), May31/89, Jun8/89.
GLYCERIAE (Kaltenbach 1843), SIPHA
Hordeum vulgare: Vancouver (CDA), Sep26/88.
GOSS YPII Glover 1877, APHIS
Capsella bursa-pastoris: Vancouver (CDA), Jun14/89.
Capsicum frutescens: Vancouver (UBC), Sep20/90.
Citrus limon: Vancouver, Mar16/90.
Cucumis sativus: Surrey, May29/89.
Solanum tuberosum: Vancouver (UBC), Sep10/90; Westham Island, Sep26/90.
HEDERAE Kaltenbach 1843, APHIS
Hedera helix: Mayne Island, Aug 13/90; Saltspring Island, Aug14/90.
HELICHRYSI (Kaltenbach 1843), BRACHYCAUDUS
Myosotis rehsteineri: Vancouver (UBC), Jul27/88.
Spiraea douglasii ssp douglasii: Vancouver, Jun27/88.
JUGLANDIS (Goeze 1778), CALLAPHIS
Juglans regia: Langley, Jul27/90.
KIOWANEPUS (Hottes 1933), MACROSIPHUM
Zigadenus venenosus var gramineus: Kootenay Park, Jul12/88.
LACTUCAE (Passerini 1860), ACYRTHOSIPHON
Lactuca sativa ‘Ithaca’: Vancouver (UBC), Oct15/90.
Lactuca serriola: Saltspring Island, Aug14/90.
LONGICAUDA (Richards 1963), EOESSIGIA
- Spiraea douglasii ssp douglasii: Vancouver, Jun9/90.
LONICERAE (Siebold 1839), RHOPALOMYZUS
Lonicera ‘Dropmore Scarlet’: Vancouver (UBC), Oct5/90.
LYTHRI (Schrank 1801), MYZUS
Prunus emarginata: Vancouver (UBC), May8/89, Jun9/90, Jul20/90.
MAXIMA (Mason 1925), ILLINOIA
Rubus parviflorus: Vancouver (UBC), Jun25/90.
MEDISPINOSA (Gillette & Palmer 1929), CINARA
Pinus contorta: Blue River, Augl3/80; Bowser, Jul7/81; Cascade, May23/57,
Jul29/54; Chemainus, May24/62; Chetwynd, Aug6/80; Christina Lake, Jul29/59;
Crowsnest Pass, Jul9/82; Duncan, Jul8/81; Grand Forks, May28/59; Greenwood,
Jun3/59; Heffley Creek, Jun26/80; Hixon, Jul31/80; Houston, Aug4/80; Jaffray,
Jul9/82; Lumby, Jun12/59, Jun16/62; McLeese Lake, Jul29/80; Mount Robson,
Aug12/80; Moyie Lake, Jull0/82; Nanoose, May25/62; Princeton, Jun17/80,
Jull/81, Jul3/81; Qualicum Beach, May25/62; Quesnel, Jul30/80, Jul31/80;
Rossland, May29/59; Shuswap Falls, Junl0/59; Squilax, Jun11/59; Stagleap
Provincial Park, Jul10/82; Taylor, Aug7/80; Terrace, Aug3/80; Tofino, May26/62;
Topley, Jul3/41; Trinity Valley, May1l4/59; Vernon, Junl6/56; Westbridge,
Jul27/77; Williams Lake, Jul29/80 (all Foottit 1987).
MENZIESIAE (Robinson 1969), ILLINOIA
Menziesia ferruginea ssp glabella: Shannon Falls, Jun26/90.
12 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
MURRAYANAE (Gillette & Palmer 1924), CINARA
Pinus contorta: Burns Bog, Jul29/82, Aug6/81 , Oct2/81; Castlegar, Jul10/82;
Chemainus, May24/62; Christian Valley, Jun21/80; Englishman River Falls Park,
May20/62; Grand Forks, May28/62; Hixon, Jul31/80; Jaffray, Jul9/82; Mackenzie,
Aug6/80; Mount Robson, Aug!12/80; Moyie Lake, Jull10/82; Naramata, Jun17/79;
Pitt Meadows, May29/79, Jun27/81 , Aug7/81, Sep18/81, Oct4/81; Qualicum
Beach, May25/62; Salmon Arm, Jun1l4/55; Sparwood, Jul9/82; Valemount,
Aug 13/80 (all Foottit 1987).
NERVATA (Gillette 1908), WAHLGRENIELLA
Arbutus menziesii: Mayne Island, Aug13/90; Saltspring Island, Aug14/90.
NICOTIANAE Blackman 1987, MYZUS
Capsicum frutescens ‘Midway’: Sidney, Apr29/89.
Cynara scolymus: Sidney, Apr29/89.
NIGRA (Wilson 1919), CINARA
Pinus contorta: Chetwynd, Aug6/80; Eighty-three Mile House, Jul29/80; Fort St.
John, Aug8/80; Heffley Creek, Jun26/80; Hixon, Aug31/80; Lakelse Lake,
Aug3/80; Mackenzie, Aug6/80; Mount Robson Provincial Park, Aug12/80; Prince
George, Jul31/80, Aug5/80; Quesnel, Jul30/80, Jul31/80; Smithers, Aug3/80;
Sparwood, Jul9/82; Taylor, Aug7/80; Tete Jaune, Aug!2/80; Valemount, Aug13/80
(all Foottit 1987).
NODULUS (Richards 1959), DIURAPHIS
Bromus tectorum: Summerland, Sep5/90.
Dactylis glomerata: Summerland, Sep6/55 (Richards 1959).
NOXIA (Mordvilko ex Kurdjumov 1913), DIURAPHIS
Hordeum vulgare: Creston, Oct17/89; Oliver, Oct18/89; Osoyoos, Oct18/89.
Triticum x aestivum: Creston, Oct17/89.
NYMPHAEAE (Linnaeus 1761), RHOPALOSIPHUM
Callitriche stagnalis: Vancouver (UBC), Jul18/90.
Nymphaea ‘Gonnere’: Vancouver, Aug15/90.
OBLIQUUS (Cholodkovsky 1896), MINDARUS
Picea glauca: Prince George, Sep18/87.
Picea sitchensis: Vancouver (UBC), Jun13/89.
*QENOTHERAE Oestlund 1887, APHIS
Epilobium ciliatum: Vancouver, Sep12/88.
ORNATUS Laing 1932, MYZUS
Anchusa azurea: Vancouver (UBC), Aug22/89.
Arctostaphylos uva-ursi: Vancouver (UBC), Jul2/90.
Callistemon viridiflorus: Vancouver (UBC), Jul3/90.
Cynara cardunculus: Vancouver (UBC), Aug8/89.
Euonymus hamiltoniana var yedoensis: Vancouver (UBC), May24/89.
Fragaria vesca var semperflorens: Vancouver (UBC), Nov3/90.
Gaultheria shallon: Vancouver (UBC), Sep28/90.
Gazania ‘Mini Star Yellow’: Vancouver (UBC), Aug8/89.
Liquidambar styraciflua: Vancouver (UBC), Jun21/90.
Lithodora diffusa: Vancouver (UBC), Aug8/89.
Rosa ‘Beauty Secret’: Vancouver (CDA), Feb15/90.
Salix lanata ‘Stuartii’: Vancouver (UBC), Aug8/89, Aug24/88.
Vaccinium corymbosum ‘Bluecrop’: Vancouver (UBC), Mar26/90.
PADI (Linnaeus 1758), RHOPALOSIPHUM
Bromus tectorum: Summerland, Sep5/90.
Zea mays: Chilliwack, Aug19/90.
*PARVICORNIS Hottes 1958, CINARA
Pinus contorta: Chetwynd, Aug6/80; Mount Robson, Aug1!2/80 (all Foottit 1987).
PASTINACAE (Linnaeus 1758), CAVARIELLA
Salix lasiandra: Widgeon Creek, Sep5/88.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 13
PENDERUM Robinson 1986, UVROLEUCON
Grindelia chiloensis: Vancouver (UBC), Oct16/90.
Grindelia nana: Vancouver (UBC), Aug16/89.
PERGANDEI (Wilson 1919), CINARA
Pinus contorta: Blue River, Aug13/80; Castlegar, Jul10/82; Christian Valley,
Jun21/80; Mackenzie, Jul6/80; Nakusp, Jun22/80; Princeton, Jun17/80, Jull/81;
Quesnel, Jul30/80, Jul3 1/80; Vancouver, Jun23/75 (all Foottit 1987).
PERSICAE (Sulzer 1776), MYZUS
Euonymus hamiltoniana: Vancouver (UBC), May24/89.
Ilex macropoda: Vancouver (UBC), May24/89.
Phoenicaulis cherianthoides: Vancouver (UBC), May24/89.
Solanum tuberosum: Westham Island, Sep26/90.
PISUM (Harris 1776), ACYRTHOSIPHON
Lathyra odorata: Vancouver, Sep20/89.
Lotus pedunculatus: Vancouver (UBC), Aug22/89.
POMI de Geer 1773, APHIS
Cotoneaster gambeli: Vancouver (UBC), Jul3/90.
POPULIMONILIS (Riley 1879), THECABIUS
Populus trichocarpa: Lost Lake, Aug17/90.
PRUNI (Geoffroy 1762), HY ALOPTERUS
Glyceria striata: Vancouver, Aug!5/90.
PTERINIGRUM Richards 1972, AULACORTHUM
Vaccinium alaskaense: Mount Seymour, Jul9/88.
RIBISNIGRI (Mosley 1841), NASONOVIA
Lactuca sativa ‘Ithaca’: Vancouver (UBC), Oct15/90.
ROSAE (Linnaeus 1758), MACROSIPHUM
Lactuca sativa: Vancouver (UBC), Jul9/90.
Rosa spinosissima: Vancouver (UBC), Jul3/90.
ROSARUM (Kaltenbach 1843), MYZAPHIS
Potentilla fruticosa: Whistler Village, Jun26/90.
Rosa pendulina: Vancouver (UBC), Jul3/90.
Rosa rubrifolia: Vancouver (UBC), Jun16/89.
SOLANI (Kaltenbach 1843), AULACORTHUM
Citrus reticulata: Kamloops, Aug6/89.
Hypericum olympicum: Vancouver (UBC), May31/89.
Malva neglecta: Vancouver, May17/90.
Oxalis regnellii: Vancouver, Jan20/90.
Spiraea douglasii ssp douglasii: Vancouver, Jun27/88.
Taraxacum officinale: Vancouver, Apr26/90.
SPIRAEAE (MacGillivray 1958), ILLINOIA
Spiraea douglasii ssp douglasii: Vancouver, Jun27/88.
SPIRAECOLA Patch 1914, APHIS
Caragana arborescens var crasseaculeata: Vancouver (UBC), Aug24/88.
SPYROTHECAE Passerini 1856, PEMPHIGUS
Populus nigra ‘Italica’: Langley, Jul27/90; Saltspring Island, Aug14/90.
STANLEYI Wilson 1915, MACROSIPHUM
Sambucus racemosa ssp pubens var arborescens: Bijoux Falls, Aug26/90; Smithers,
Aug26/90.
STELLARIAE Theobald 1913, MACROSIPHUM
Silene armeria: Vancouver, Jul2/90.
SYMPHORICARPI (Thomas 1878), APHTHARGELIA
Symphoricarpos x chenaultii: Vancouver (UBC), May24/90, Jun21/90.
TENUICAUDA Bartholomew 1932, MACROSIPHUM
Urtica dioica: Peace Arch Park, Jul2/90.
14 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
TESTUDINACEUS (Fernie 1852), PERIPHYLLUS
Acer saccharinum: Pemberton, Jun2/89.
TILIAE (Linnaeus 1758), EUCALLIPTERUS
Tilia cordata: Vancouver, Aug15/90.
TREMULAE (Linnaeus 1761), ASTIPHUM
Picea engelmannii: Nelson, Nov20/87.
Picea glauca: Quesnel, Oct6/87.
ULMIFOLII (Monell 1879), TINOCALLIS
Ulmus americana: Okanagan Lake Park, Aug25/89.
ACKNOWLEDGEMENTS
We wish to thank Dr. A.G. Robinson, University of Manitoba, Winnipeg, Manitoba, Dr.
R.L. Blackman, British Museum (Natural History), London, England and Dr. M.B.
Stoetzel, Systematic Entomology Laboratory, U.S.D.A., Beltsville, Maryland for valuable
aid and advice in aphid identification; and Dr. G.B. Straley, U.B.C. Botanical Garden,
Vancouver, B.C. for host plant identification.
REFERENCES
Anonymous. 1982. National list of scientific plant names. Vol. |. List of plant names. SCS-TP-159. U.S.D.A.
Anonymous. 1976. Hortus Third: A concise dictionary of plants cultivated in the United States and Canada.
MacMillan Publishing Co., Inc. N.Y. Collier MacMillan Publishers, Lond.
Eastop, V.F., and R.L. Blackman. 1988. The identity of Aphis citricola van der Goot. Syst. Entomol. 13: 157-
160.
Eastop, V.F., and D. Hille Ris Lambers. 1976. Survey of the world’s aphids. Dr. W. Junk b.v., Publisher, The
Hague.
Foottit, R.G. 1987. Morphometric analysis of character variation and taxonomic discrimination among a com-
plex of species of the genus Cinara (Homoptera: Aphididae: Lachnidae). Ph.D. Thesis, Simon Fraser Univ.
Forbes, A.R., and C.K. Chan. 1989. The aphids (Homoptera: Aphididae) of British Columbia. 19. Further addi-
tions. J. ent. Soc. Brit. Columbia 86:82-88.
Forbes, A.R., and C.K. Chan. 1988. The aphids (Homoptera: Aphididae) of British Columbia. 18. Further addi-
tions. J. ent. Soc. Brit. Columbia 85:87-97.
Forbes, A.R., and C.K. Chan. 1987. The aphids (Homoptera: Aphididae) of British Columbia.
tions. J. ent. Soc. Brit. Columbia 84:66-72.
Forbes, A.R., and C.K. Chan. 1986a. The aphids (Homoptera: Aphididae) of British Columbia. 15. Further addi-
tions. J. ent. Soc. Brit. Columbia 83:70-73.
Forbes, A.R., and C.K. Chan. 1986b. The aphids (Homoptera: Aphididae) of British Columbia. 14. Further addi-
tions. J. ent. Soc. Brit. Columbia 83:66-69.
Forbes, A.R., and C.K. Chan. 1985. The aphids (Homoptera: Aphididae) of British Columbia.
tions. J. ent. Soc. Brit. Columbia 82:56-58.
Forbes, A.R., and C.K. Chan. 1984. The aphids (Homoptera: Aphididae) of British Columbia.
tions. J. ent. Soc. Brit. Columbia 81:72-75.
Forbes, A.R., and C.K. Chan. 1983. The aphids (Homoptera: Aphididae) of British Columbia. 11. Further addi-
tions. J. ent. Soc. Brit. Columbia 80:51-53.
Forbes, A.R., and C.K. Chan. 1981. The aphids (Homoptera: Aphididae) of British Columbia. 9. Further addi-
tions. J. ent. Soc. Brit. Columbia 78:53-54. s
Forbes, A.R., and C.K. Chan. 1980. The aphids (Homoptera: Aphididae) of British Columbia. 8. Further addi-
tions and corrections. J. ent. Soc. Brit. Columbia 77:38-42.
Forbes, A.R., and C.K. Chan. 1978. The aphids (Homoptera: Aphididae) of British Columbia. 6. Further addi-
tions. J. ent. Soc. Brit. Columbia 75:47-52.
Forbes, A.R., and C.K. Chan. 1976. The aphids (Homoptera: Aphididae) of British Columbia. 4. Further addi-
tions and corrections. J. ent. Soc. Brit. Columbia 73:57-63.
Forbes, A.R., C.K. Chan and R.G. Foottit. 1982. The aphids (Homoptera: Aphididae) of British Columbia. 10.
Further additions. J. ent. Soc. Brit. Columbia 79:75-78.
Forbes, A.R.. B.D. Frazer and C.K. Chan. 1974. The aphids (Homoptera: Aphididae) of British Columbia. 3.
Additions and corrections. J. ent. Soc. Brit. Columbia 71:43-49.
Forbes, A.R., B.D. Frazer and H.R. MacCarthy. 1973. The aphids (Homoptera: Aphididae) of British Columbia.
1. A basic taxonomic list. J. ent. Soc. Brit. Columbia 70:43-57.
Taylor, R.L., and B. MacBryde. 1977. Vascular plants of British Columbia—A descriptive resource inventory.
Tech. Bull. No. 4. The Botanical Garden. Univ. of B.C.
—
6. Further addi-
—
3. Further addi-
—
2. Further addi-
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 15
Honey bee foraging on dandelion and apple
in apple orchards
D.F. MAYER and J.D. LUNDEN
DEPARTMENT OF ENTOMOLOGY
WASHINGTON STATE UNIVERSITY, I[AREC
PROSSER, WA 99350
ABSTRACT
A four-year study was conducted to determine if honey bees foraging on dandelion switched
to apple bloom when dandelion flowers closed in the afternoon. The number of honey bees
foraging on dandelion decreased significantly in the afternoon with no significant increase of
honey bee numbers on apple. Four thousand honey bees were marked while foraging on dan-
delion but only two were later observed working apple. Most honey bees foraging on dande-
lion for nectar do not switch to apple bloom after dandelions close.
Insecta, Honey bees, Pollinators, Dandelion, Apple
INTRODUCTION
‘Delicious’ apple requires cross-pollination and honey bees (Apis mellifera L.) are the pri-
marily pollinators (Mayer, et al. 1986). Dandelions (Taraxacum officinale) are frequently
found on the orchard floor of apple orchards in the Pacific Northwest and British
Columbia. Dandelions bloom at the same time as apples and may compete with apple
flowers for the limited number of bees available for foraging. On warm sunny days dan-
delion flowers mostly close by 1330 and remain closed for the day. Even on cloudy days
most dandelions close in the afternoon. Kremer (1950) suggested that since dandelions
closed at midday there was no competion and bees deserting the closed dandelion foraged
on apple. Percival (1955) studied pollen presentation of dandelion and apple and pointed
out that dandelion may not lure bees from fruit trees. Filmer (1941) found about equal
numbers of bees foraging on apple and dandelion and supposed that dandelion was a
major competitor to fruit. Free (1968) using pollen traps and marked honey bee pollen
collectors found a great percentage of the pollen collected by colonies placed in fruit
orchards was dandelion and marked pollen collectors seldom changed from dandelion to
fruit. He concluded that dandelion was a serious competitor for apple. However, he
worked only with pollen collectors although he reported that most bees visit dandelion for
nectar rather than pollen. The purpose of this study was to determine if honey bees forag-
ing on dandelion for nectar switched to apple bloom when dandelion flowers close.
MATERIALS AND METHODS
A ‘Bisbee’ Delicious apple orchard planted near Prosser, WA in 1976 on a 10 x 18 ft spac-
ing was used. Experiments were conducted during late April when the trees were at full
open bloom in 1986, 1987, 1988 and 1989. A nearly solid cover crop of blooming dande-
lions occurred on the orchard floor every year. Each year 1,000 honey bees foraging on
dandelion between 0930 and 1000, were marked with a small cheesecloth bag containing
orange fluorescent powder. The cheesecloth bag was gently tapped on the upper abdomen
of individual bees as they collected nectar from dandelion. The same 0.25 acre plot in the
orchard was used every year. Each year the total number of honey bees and number of
marked bees per apple tree per minute (20 replications) and per square meter of dande-
lions per 30 seconds (20 replications) were recorded at 0900, 1130 and 1430 on the same
day the bees were marked and at 0900, 1130 and 1430 on the following day. The first
count on the first day was prior to marking honey bees. In all years, all or nearly 100% of
the dandelion flowers closed between 1200 and 1300 and remained closed for the day.
Data were analyzed by ANOVA using Tukey’s multiple mean comparison test (Steel and
Torrie, 1980).
16 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
Table 1
Mean number of honey bees per apple tree per minute and per square meter of dandelion
per 30 seconds. Prosser, WA.
1986 1987 1988 1989
Dande- Dande- Dande- Dande-
Time Apple lion Apple _ lion Apple _ lion Apple _ lion
Day 1
0900 4a 14a 5a 24a 4a 28a 15a 16a
1130 10b 21a 4a 30a ae 35a 22a 20a
1430 12b Ib 4a Ob 6a 3b l7a 2b
Day 2
0900 Sa loa 6a 7a 6a 29a 9a Ta
1130 12b 228 8a 7a Sa 30a 13a 21b
1430 14b Ob 8a lb 6a 7b lla ke
Means within a column and day followed by the same letter are not significantly different (Tukey’s multiple
mean comparison test, P=0.5).
Table 2
Mean percent of honey bees observed at each time period on apple bloom and dandelion flowers
with orange flourescent powder on their bodies. One-thousand honey bees foraging on dandelion
were marked between 0930 and 1000 after taking the 0900 counts on day 1. Prosser, WA.
1986 1987 1988 1989
Dande- Dande- Dande- Dande-
Time Apple _ lion Apple _ lion Apple lion Apple _ lion
Day 1
0900 0 0 0 0 0 0 0 0
1130 0 48 0 53 0 46 0 35
1430 0 0 0 0 0 40 0.5 63
Day 2
0900 0 28 0 10 0 | 0 33
1130 0 32 0 20 0 28 0 30
1430 0 0 0 0 21 0 23
RESULTS & DISCUSSION
As expected, honey bee foraging on dandelion decreased significantly in the afternoon
when dandelion flowers closed (Table 1). However, there was no significant increase in
honey bee foraging on apple flowers at 1430 when dandelion blooms were closed as com-
pared to 1130 when they were open (Table 1). Higher numbers of honey bees foraging on
apple after dandelion closed would indicate that bees foraging on dandelion did switch to
apple. This was not the case in any of the four years. During 1986-1988, none of the 3,000
honey bees marked with orange powder while collecting nectar from dandelion was
observed foraging on apple either on the day of marking or the following day (Table 2). In
1989, 2 bees out of the 1,000 marked were observed working apple at 1430 after dande-
lions closed (Table 2). Clearly, most honey bees do not switch to apple after dandelions
close. Of the bees marked on dandelion at 0900, 35% to 63% were observed working dan-
delion at 1130 or 1430 on the day of marking and 10 to 33% on the next day (Table 2).
The marking technique proved to be a good method for tracking individual bees. For
example, at 1130 on day 1 in 1987, of 600 bees recorded on dandelion 318 were marked
bees. Free (1970) suggested that an individual bee’s foraging area is limited. We found
that many marked bees continue foraging in our 0.25 acre test plot indicating that most
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 Ve
bees work a limited area. Honey bees foraging dandelion for nectar do not switch to apple
bloom after dandelions close in the afternoon. Dandelions are beneficial to the bee
colonies in providing pollen and nectar, but they appear to be a serious drain on the num-
bers of available pollinators for apple.
ACKNOWLEDGEMENT
We thank Lora Rathbone and Gene Milizcky for their help and Lewis Orchards for the
use of their orchard. We also thank the Washington Tree Fruit Research Commission for
partial funding of this research.
REFERENCES
Filmer, R.S. 1941. Honeybee population and floral competition in New Jersey orchards. J. Econ. Entomol.
34:198-191.
Free, J.D. 1968. Dandelion as a competitor to fruit trees for bee visits. J. Appl. Ecol. 5:169-178.
Free, J.D. 1970. Insect Pollination of Crops. Academic Press, New York.
Kremer, J.C. 1950. The dandelion and its influence on bee behavior during the fruit blossoming period. Proc.
Amer. Soc. Hort. Sci. 55:14-146.
Mayer, D.F., C.A. Johansen, D.M. Burgett. 1986. Bee pollination of tree fruits. Wash. St. Univ. Coop. Ext.
PNW 0282. 10 pp.
Steel, R.G.D. and J.H. Torrie. 1980. Principles and Procedures of Statistics. A Biometrical Approach. 2nd ed.
McGraw-Hill, New York.
Percival, M.S. 1955. The presentation of pollen in certain angiosperms and its collection by Apis mellifera. New
Phytol. 54:353-68.
Unseasonably low fall and winter temperatures affecting
mountain pine beetle and pine engraver beetle populations
and damage in the British Columbia Chilcotin Region
L. SAFRANYIK and D.A. LINTON
FORESTRY CANADA, PACIFIC FORESTRY CENTRE
506 W. BURNSIDE RD., VICTORIA, B.C. V8Z IM5
ABSTRACT
Unseasonably low temperatures in the fall and winter of 1984 and the fall of 1985 resulted in
the decline and termination by 1987 of a major mountain pine beetle infestation which had
been in progress since the late 60’s. Following the winter of 1984-85, brood survival on
lodgepole pine trees in plots near Tsuh Lake in the west-central Chilcotin area of British
Columbia was restricted to the lower 0.5 m of infested boles, and the estimated average
emergence of female beetles per tree was about 10% of the number required for replacement
of the parent generation. Pine engraver beetle populations which built up during the moun-
tain pine beetle epidemic killed many trees in 1985 and 1986, but collapsed by 1987, due
mainly to tree resistance and other natural factors. The rise and fall of tree mortality from the
pine engraver within the plots paralleled that in the rest of the central Chilcotin following the
collapse of the mountain pine beetle outbreak.
INTRODUCTION
Mortality from cold is one of the major factors determining the distribution and abun-
dance of the mountain pine beetle (Dendroctonus ponderosae Hopk.)(Safranyik 1978;
Amman and Cole 1983). Mountain pine beetles normally overwinter as late-instar larvae,
the stage at which they are the most cold-hardy (Safranyik 1978; Amman and Cole 1983).
Cold-hardiness of mountain pine beetle increases with the accumulation of glycerol in
body fluids in response to gradually decreasing temperatures in the fall and early winter
is J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
Table 1
Selected minimum daily temperatures” and month-end snow depths at Alexis Creek B.C. in 1984 and 1985.
(Source: Monthly records of Meteorological Observations in Canada 1984, 1985.
Environment Canada, Atmospheric and Environment Service.)
Date Minimum daily Snow depth
temp. (°C) (cm)
1984
Oct. 30 -23.0
Oct. 31 -31.0 7
Nov. 1 -21.0
Dec. 29 -40.0
Dec. 30 -43.0
Dec..31 -38.0 36
1985
Nov. 11 -27.5
Nov. 12 -20.0
Nov. 22 -31.0
Nov. 23 -35.0
Nov. 24 -23.5
Nov. 25 -26.0
Nov. 26 -39.0
Nov. 27 -43.0
Nov. 28 -39.0
Nov. 29 -36.0
Nov. 30 -29.0 16
Dec. 1 -34.5
Dec: 2 -32.0
* The estimated lethal low temperature threshold for larvae during the winter period is near -38°C;
during the late October-early November period it is near -26°C. (Safranyik ef al. 1974, Fig.25)
(Somme 1964). Maximum cold-hardiness is attained by December-January, and some
large larvae can survive short exposures to -38°C during this period. During the fall
before maximum hardiness is attained and as it wanes in the spring, the insects are sus-
ceptible to extreme cold, so that unseasonably low temperatures (less than -26°C) can
cause widespread mortality (Safranyik ef al. 1974; Safranyik 1978).
Unseasonably low temperatures in late October and late December of 1984, and again
for several days in November of 1985, provided an opportunity to observe their effect on
mountain pine beetle populations, tree mortality, and the incidence of attacks by some
associated species of bark beetles. The plots had been established in June 1985 to investi-
gate the dispersal of mountain pine beetle within stands. In this paper we present data
which describe the infestation trends of mountain pine beetle and /ps pini Swaine (pine
engraver beetle) between 1984 and 1987, and some characteristics of the infested trees.
MATERIALS AND METHODS
The plot area was established in a stand of mature lodgepole pine (Pinus contorta var. lat-
ifolia Doug.) near Tsuh lake, about 80 km west of Williams Lake, British Columbia,
within a massive epizootic of mountain pine beetle which began in the late 1960s (Wood
and Van Sickle 1987). The study area was generally flat, 5.6 ha in area with about 2 ha of
esker-like ridges 2-3 m in height in the southeast portion. It was surrounded on three sides
by open meadows 10 to 40 m wide, and on the fourth by a stand of lodgepole pine less
than 40 years old containing a few veteran Douglas-firs (Pseudotsuga menziesii (Mirb.)
Franco). Within the study area, the tree cover averaged 592.3 stems per ha with diameter
at breast height (dbh) greater than 5 cm, consisting of 83% lodgepole pine, 11% engel-
mann spruce (Picea engelmannii Parry)(mainly in depressions) and the balance scattered
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 19
Douglas-fir and aspen (Populus tremuloides Michx.). The average age of the lodgepole
pines was 102 years in 1985.
In 1985 all trees over 5cm dbh were counted by species, and the dbh of trees attacked
by mountain pine beetle or pine engravers in 1984 and 1985 were tallied. In the years
1986 and 1987 the dbh of all newly infested lodgepole pine trees were recorded. Tree
heights and maximum height of attack were estimated for a random sample of infested
trees using an Abney level; binoculars were used to determine the location of the highest
attacks where necessary.
Mountain pine beetle attack and brood densities and totals per tree were estimated for
trees infested in 1983 and 1984 only and were multiplied by the total infested bark surface
area to estimate total population within the study area annually. Emergence in 1984 was
estimated based on counts of emergence holes on 15 x 15 cm areas of bark at breast
height on trees attacked in 1983. In 1985, the density of emergence of mountain pine bee-
tle was estimated using total counts of beetles which emerged from caged infested bolts
and counts of emergence holes on bark areas painted with light colored latex paint to
enhance the visibility of the holes (Safranyik and Linton 1985). Brood and attack totals
per tree were estimated based on measurements of dbh, total or infested tree height, and
attack and brood densities at breast height (Safranyik 1988).
Minimum daily temperature and snow accumulation for the years 1984-85 (Table 1)
were obtained using Environment Canada records from Alexis Creek, about 30 km west
of the study area.
RESULTS AND DISCUSSION
The effect of unseasonable cold on mountain pine beetle
Trees attacked in 1984 are described by the data in Table 2. The mean mountain pine bee-
tle attack height (11.36 m) was about 60% of total tree height, which is considered normal
for the dbh and height of the attacked trees (Safranyik, 1969). The maximum height at
which live mountain pine beetle brood were found, however, was only 63 cm (mean 53
cm)-less than 5% of the infested height. Normally, some beetles mature near the top of
the infested bole region. Careful examination of infested trees in mid-May of 1985 indi-
cated that survival was confined to the bark areas which were probably below snow dur-
ing the winter. Recorded snow accumulation at Alexis Creek (Table 1) was less than the
average height of live brood. It 1s, however, likely that snow depth inside the stand was
greater than in the open area where the weather station is located. Dead larvae found
beneath the bark higher up the stems were dark grey to black, and stretched out; both of
these symptoms are indicative of winter mortality.
Temperature records (Table 1) show that temperatures near or below the lethal early
winter threshold of about -26°C (Safranyik et al. 1974) occurred during 3 days at the end
of October and during 2 days at the end of December in 1984. On October 31 and
December 30 and 31, even the mean daily temperatures were as low as or lower than the
fall lethal threshold of ca -26°C or the late-winter lethal threshold of ca -38°C. In 1985,
minimum daily temperatures near or below the -26°C threshold were recorded for 13 days
between November 10 and December 2; the last 11 of these occurred in an unbroken
sequence. In contrast, the records for the years 1975-1983 show no periods when the tem-
peratures fell below the estimated lethal minima for more than two consecutive days.
In 1985 the estimated mean number of potential emerging mountain pine beetle
females per tree (1192, Table 2) Represented a static or increasing population over the
previous generation (the mean number of attacks per tree in 1984 was 458), even after
allowing for loss of beetles during dispersal and host colonization (Cole and Amman
1969). The mean actual emergence per tree (119, Table 2) was about 10% of the potential
(i.e. the expected emergence without complete above-snow mortality). Considering a
female:male ratio of 2:1 and a flight-establishment loss of 40% (Cole and Amman, 1969),
the average of 119 emergents per tree represents 79 females, or 47 attacks. This is about
10% of the average attacks per tree made by the parent generation.
20 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
Table 2
Statistics describing lodgepole pine at Tsuh Lake infested in 1984 by mountain pine beetle.
Variables Mean + S.D. N
Diameter (dbh, aa 23.097 35
Total height (m) 18:84 2.0 12
Attack height (m) LT 3 2:3:0 10
Brood height (m) G23. 0.1 ih,
Attacks/m? at dbh 133.3 +.47.5 13
Attacks/tree ” 458.3 + 158.7 13
Emergence/m~ 212) 2 1S.6 10
Emergence/tree < 1S 8502, 10
Estimated emergence 1192.4 + 850.3 10
/tree for 1985***
+ Estimated as in Safranyik 1988 (eq. 13).
oe Based on emergence data from caged bolts and emergence holes on infested bolts
(Safranyik and Linton 1985).
*** Assumes the usual distribution of brood adults over the total infested bole. Based on mean
no. of emerged beetles/tree (see footnote **), mean height of live brood on the bole and a
cumulative function for brood on infested bole height (Safranyik 1988, eq. 16).
The mean number of trees per ha attacked by mountain pine beetle in 1985 was 10.23,
or about 9% of the 1984 mean (Table 3). This agrees well with the corresponding estimate .
of 10% based on brood survival. This comparison assumes, however, that mean surface
area attacked per tree and mean attack density did not change over the two years. These
variables were not estimated for 1985 attacks. Numbers of trees attacked by mountain
pine beetle further declined in 1986, and by 1987 no new attacks were found on the plot.
Response of pine engraver beetle population to decline of mountain pine beetle
No trees were killed in 1984 by the pine engraver beetle, a major associate of the moun-
tain pine beetle (Sartwell et al. 1971). From 1985 to 1987, the mean numbers of engraver-
attacked trees per ha were 15.02, 21.51, and 2.05, respectively. The mean dbh was small-
er than that of trees killed by mountain pine beetle, but the difference was not statistically
significant (p>0.05). The pine engraver normally attacks the uninfested tops and lightly
infested areas of trees killed by mountain pine beetle. Consequently, during large out-
breaks of mountain pine beetle, large engraver populations can build up. Because these
insects overwinter in the duff, populations are not affected appreciably by severe winter
temperatures. In 1985 and 1986 large engraver populations (which developed in trees
killed by mountain pine beetle) attacked live trees in the absence of trees killed by moun-
tain pine beetle. Many trees colonized by the pine engraver also bore a few mountain pine
beetle attacks, and some from Pityogenes plagiatus knechteli Swaine, another common
associate.
This study is the first to present data on the collapse of a mountain pine beetle outbreak
due to cold temperatures, and the subsequent infestation by the pine engraver. After the
collapse of the massive Mountain pine beetle infestations in the Chilcotin during 1985-86,
pine engraver killed large numbers of the residual trees, mainly along the edges of cut
blocks and rights-of-way (Wood and Van Sickle 1986, 1987). As expected, these infesta-
tions invariably declined in 2-3 years as populations suffered heavy mortality, apparently
from host resistance, intraspecific competition and natural enemies (Sartwell et al. 1971).
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 aa |
Table 3
Numbers/ha and mean dbh of lodgepole pine trees attacked by the mountain pine beetle
(MPB) and pine engraver beetle (/ps) from 1984 to 1987
Year of Beetle Mean dbh.
Attack species Trees/ha (cm) + S.D. N
1984 MPB 109.4 25.02 + 5.74 35
Ips 0 - -
1985 MPB 10.23 21.48 + 3.44 60
Ips 15.02 18.77 + 4.88 88
1986 MPB 7.68 23.17 + 5.44 45
Ips Zest 18.58 + 4.00 126
1987 MPB 0 - -
Ips 205 i223 653- 7 12
REFERENCES
Amman, G.D. and W.E.Cole. 1983. Mountain pine beetle dynamics in lodgepole pine forests. Part II:
Population dynamics. USDA For. Serv. Gen. Tech. Rept. INT-145. Intermountain For. and Range Expt.
Stn., Ogden UT. 60p.
Cole, W.E. and G.D.Amman. 1969. Mountain pine beetle infestations in relation to lodgepole pine diameters.
USDA For. Serv. Res. Note INT-95. Intermountain For. and Range Expt. Stn., Ogden UT. 7p.
Safranyik, L. 1969. Development of a technique for sampling mountain pine beetle populations in lodgepole
pine. PhD Thesis. Univ. British Columbia, Vancouver. 195pp.
——- 1978. Effects of climate and weather on mountain pine beetle populations. pp78-86 in The theory and
practise of mountain pine beetle management in lodgepole pine. D.Kibbee, ed., Symp Proceedings, Wash.
State Univ., Pullman. April 25-27, 1978.
—- 1988. Estimating attack and brood totals and densities of the mountain pine beetle in individual lodgepole
pine trees. Can. Entomol. 120:323-331.
——- and D.A.Linton. 1985. The relationship between density of emerged Dendroctonus ponderosae
(Coleoptera:Scolytidae) and density of exit holes in lodgepole pine. Can. Entomol. 117:267-275.
-, D.M.Shrimpton and H.S.Whitney. 1974. Management of lodgepole pine to reduce losses from the moun-
tain pine beetle. Environment Canada Forestry Technical Report 1. October, 1974. Pac. For. Res. Cent.,
Victoria, B.C. 24 pp.
Sartwell, C., Schmitz, R.F., and Buckhorn, W.J. 1971. Pine engraver, Jps pini, in the Western States. U.S. Dep.
Agric. For. Serv. For. Pest Leafl. 122.
Schmitz, R.F. 1988. Understanding scolytid problems in lodgepole pine forests: The need for an integrated
approach. pp 231-241 in Integrated control of scolytid bark beetles. T.L.Payne and H. Saarenmaa, eds.,
Proceedings IUFRO Working Party and XVII Internat. Congr. Entomol. Symp., Vancouver, B.C., Canada,
July 4, 1988. 356 pp.
Somme, L. 1964. Effects of glycerol on cold-hardiness in insects. Can. J. Zool. 42:87-101.
Wood, C.S., A. Van Sickle. 1987. Forest insect and disease conditions British Columbia and Yukon 1986. Can.
For. Serv. Pac. For. Res. Cent. BC-X-287. 35pp.
Wood, C.S., A. Van Sickle. 1988. Forest insect and disease conditions British Columbia and Yukon 1987. Can.
For. Serv. Pac. For. Res. Cent. BC-X-296. 40pp.
p28) J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
An improved system for
mass-rearing codling moths'
H. H. TOBA and J F. HOWELL
FRUIT AND VEGETABLE INSECT RESEARCH
USDA, ARS, YAKIMA, WASHINGTON 98902
ABSTRACT
Various modifications were made to a system for mass-rearing the codling moth, Cydia
pomonella (L.), on formulated diets and immature apples to improve production efficiency
and to reduce exposure of workers to formaldehyde and moth scales. The modifications
included: an improved oviposition cage, an oviposition cabinet, an apparatus to surface-ster-
ilize eggs with formaldehyde fumes, a moth scale removal system in the adult collection
room, and disposable adult eclosion containers. This system is suitable for research requiring
large numbers of selected stages of the codling moth.
INTRODUCTION
The codling moth, Cydia pomonella (L.), a serious pest of several deciduous fruits and
walnuts, has been mass-reared at the USDA, ARS research facility at Yakima for over 20
years. In the past, it was reared primarily for use in studies of the sterile insect technique,
population movement and suppression, and pheromones (Hamilton and Hathaway 1966).
Current programs in postharvest quarantine treatment research require large numbers of
selected stages of the codling moth for use in studies to evaluate the efficacy of proposed
treatments, such as fumigation, irradiation, and cold or controlled atmosphere storage. For
example, in order to have a 99.9% confidence level in quarantine security, 93,616 insects
are needed per treatment (Chew and Ouye 1985). Through the years, many changes have
been made in codling moth diet (Howell 1967, 1970, 1971, 1972) and rearing procedures
(Hathaway 1967, Hathaway et al. 1972, Hutt et al. 1972) to meet the need for more safe,
efficient and cost-effective rearing.
This paper describes further modifications made to the rearing system, particularly to
reduce worker exposure to hazardous materials, such as moth scales and formaldehyde,
and the current procedures used to mass rear the codling moth at this location.
EGG COLLECTION AND HANDLING
Eggs are obtained using the oviposition cage of Hathaway ef al. (1972) with one change;
the muslin cloth liner in the top portion is replaced with 16-mesh wire screen. The ovipo-
sition substrate is either waxed paper or polystyrene pellets (Dow Chemical Co., granula-
tion number 451-27-35). Waxed paper sheets are first crumpled, then flattened, before
they are fitted into the bottom of the cages. Moths prefer to oviposit on crease lines in the
sheets rather than on flat, smooth surfaces. In the use of pellets, 250 g are placed in each
cage. Adults are transferred from collection containers to oviposition cages in a hood
located in the adult collection room maintained at about 3°C (see below). Each cage holds
250-300 unsexed moths, which produce about 6000 eggs.
The prepared oviposition cages are held in a plywood cabinet, which was designed to
control environmental conditions and remove moth scales (Fig. 1). The cabinet measures
2.9 m wide, 0.6 m deep, and 2.0 m high, and houses a heater, air filters (SW512-D
Extended Surface Air Filter 50.8 x 63.5 x 2.5 cm, Dayton Electric Mfg. Co., Chicago, IL),
a blower, and humidifiers. Sliding glass doors give access to two sets of five open metal
wire shelves, 25 cm apart, each shelf with a 30-watt fluorescent light overhead. Air from
the room, which is maintained at 23 + 3°C, enters the plenum through the blower, passes
Footnote
|. Mention of a proprietary product does not constitute an endorsement by the USDA.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 23
Fig. 1. Codling moth oviposition cabinet: (a) blower, (b) heater (hidden), (c) humidifier, (d) filters.
Direction of air flow indicated by arrows.
over the heater, and enters the cabinet at the top, circulating in the cabinet at a rate of 0.15
m? per min. The air then enters the plenum at the bottom, passes through the air filters
and is exhausted into the room. The cabinet is maintained at 24 + 3°C, 62 + 10% RH, and
16:8 (L:D) photophase.
After a 5-day oviposition period the cages are removed from the cabinet and trans-
ferred to the hood described above. After about 15 min in the cold room the adults
become inactive, and are collected by vacuum and discarded.
Eggs used in mass-rearing need to be surface sterilized to eliminate surface contamina-
tion by pathogenic and non-pathogenic microorganisms. In the past, waxed paper sheets
or pellets with codling moth eggs were dipped in a 0.1% sodium hypochlorite solution for
2 min (Hamilton and Hathaway 1966, Hathaway er al. 1972) or in formaldehyde solution
(Howell 1970). These methods were time-consuming and hazardous. Furthermore, pellets
tended to clump together when wet, and some eggs dislodged from waxed paper. We
found that eggs tolerated formaldehyde vapor for 120 min without effect on hatching or
the ability of neonate larvae to enter fruit. Tests showed that there were no codling moth
larval deaths due to granulosis virus when eggs were fumigated with formaldehyde for 45
min (J. S. Tebbets and P. V. Vail, ARS Stored Products Research Laboratory, Fresno,
CA, personal communication). Our procedure for the past 7 years to surface-sterilize eggs
has been to fumigate them with formaldehyde vapor for 90 min at room temperature
(23;C).
The fumigation apparatus, constructed of Plexiglas® and located in a fume hood, mea-
sures 41 cm deep, 26 cm wide, and 80 cm high (Fig. 2). It holds four removable wooden-
framed trays of 0.36-cm mesh hardware cloth spaced 13 cm from the top of the chamber
to the top tray and 13 cm between trays. A 10-cm diam exhaust fan is located at the top of
the apparatus. Three 2.2-cm diam ventilation holes are located on each side, 5 cm from
the bottom, for air to enter the apparatus during evacuation of formaldehyde fumes before
the hinged door in front is opened. A 28 x 15 x 10 cm stainless steel container, with a lid,
containing the undiluted formaldehyde sits on the floor of the chamber.
For fumigation, egg-laden pellets held on 18 x 16 mesh saran screen are placed on the
trays in the fumigation chamber. Egg-laden waxed papers are placed directly on the trays.
The lid to the formaldehyde container is removed and the door closed. At the end of the
24 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
SS
Fig. 2. Fumigation apparatus in fume hood for surface-sterilizing codling moth eggs with formalde-
hyde fumes: (a) exhaust fan, (b) empty tray, (c) tray with egg-laden waxed paper, (d) tray with egg-
laden polystyrene pellets, (e) stainless-steel container for formaldehyde.
fumigation period, the exhaust fan is turned on and formaldehyde fumes evacuated for 2-
3 min. The formaldehyde tank lid is then replaced and the eggs removed.
LARVAL REARING
Formulated diet
Various formulated diets have been used to mass-rear the codling moth at this laboratory
(Hamilton and Hathaway 1966; Howell 1967, 1970, 1971, 1972). However, we have been
using a diet developed by Howell and Toba (unpublished) for the past 7 years because it
has been the most satisfactory one for our purpose. To infest trays of diet a waxed paper
sheet with eggs is cut into 20 equal squares, each generally having about 300 eggs. Five
squares are placed on the diet in each stainless steel tray (45 x 26 x 7 cm) and the tray is
covered with a muslin cloth lid with a wood frame. The weight of the frame, which
hangsover the edge of the tray, holds the cloth snug against the lip of the tray to prevent
larvae from escaping and to help control dehydration of the diet. The trays are placed on
wheeled metal racks and maintained at 23 + 2°C, 50 + 10% RH, and 16:8 (L:D) pho-
tophase. Seven days later the waxed paper squares are removed. Fifteen days after egg
infestation, 40.5 x 1.9 cm fluted fiberboard strips are placed in each tray to serve as
cocooning sites for mature larvae. The strips are placed in spaces between the diet and the
sides of the tray, plus three to four on the surface of the diet.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 25
Fig. 3. Scale removal system in codling moth adult collection room: (a) filtering apparatus, (b)
polyvinyl! chloride tubing, (c) dryer duct sleeve, (d) moth collection container.
Immature apples
When rearing codling moths on apples, one layer of immature, thinning apples previously
washed in water is placed in each disposable fiberboard tray (Hathaway 1967). Because
water does not remove pesticides that are harmful to codling moths, apple samples are
analyzed for residue before using. Each tray is inoculated with about 1500 eggs by sprin-
kling a given volume (usually 25 ml) of egg-laden pellets. The number of eggs is based on
counts in a sample of pellets. The trays are then covered with 18 x 16 mesh saran screen,
fitted with tops, and placed on wheeled metal racks. If mature cocooning larvae, pupae or
adults are desired, fiberboard pupation strips are placed on the apples. The trays are main-
tained at 23 + 2°C, 60 + 10% RH, and 16:8 (L:D) photophase.
COCOON AND ADULT COLLECTION AND HANDLING
Fiberboard strips with cocooned larvae are harvested from trays of diet or immature
apples. A system developed by Hutt e¢ al. (1972) to automatically collect emerged moths
utilizes two adjoining rooms: an unlighted eclosion room maintained at 24 + 2°C and 70 +
10% RH, and a lighted room maintained at about 3°C where the moths are collected.
Moths emerging in the dark eclosion containers are attracted to light in the cold room
through tubes attached to adult collection containers. Various modifications have been
made to this system, primarily to control moth scales.
Eclosion containers made of galvanized sheet metal (Hutt et al. 1972) have been
replaced with disposable fiberboard containers of the same dimensions. Cocooning strips
26 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
are loosely stacked criss-cross in the fiberboard containers instead of on racks used in the
metal containers. The fiberboard containers are disposed of after use, thereby eliminating
the need to clean and sterilize them and reducing worker exposure to moth scales and
microbial contamination.
The problem of moth scales in the cold room where the moths are collected and han-
dled has been decreased with a scale removal system (Fig. 3). One end of polyvinyl] chlo-
ride tubing is attached to a box housing a blower and an air filter (TA Pinch Pleat 25.4 x
50.8 x 2.5 cm, Environmental Filter Corp., Santa Rosa, CA). Moth collection containers
with screen bottoms are connected to the tubing by means of short pieces of flexible dryer
duct sleeves. A small hood in the cold room used to transfer moths is also connected to
the scale removal system by polyvinyl! chloride tubing. The hood is not vented outdoors to
conserve cold air in the room.
SANITATION
When mass-rearing insects, sanitation is essential to control contamination of diet, equip-
ment and insect by microorganisms. Certain measures have been taken to minimize these
problems in rearing the codling moth. After each use, moth collection containers and
Oviposition cages are cleaned in a dishwasher. Used diet trays are held in a freezer at
about -18°C for 2 days to kill any insects present, then cleaned and autoclaved at 115.5°C
and 18-20 psi for | hr. Diet tray covers are similarly cleaned and autoclaved for 0.5 hr.
The autoclave opens at both ends, each end opening into a separate room. Dirty trays and
covers are cleaned and placed 1n the autoclave in one room (dirty room), and removed and
stored in the other room (clean room) after autoclaving. Used apple rearing trays and
adult eclosion containers with cocooning strips are held in a room at about 49°C for 12 hr
to kill any insects present before discarding them. Walls and floors are cleaned weekly
with household ammonia or detergent.
Scavenger mites (family Ascaidae) sometimes become a problem when larvae are
reared on immature apples. To prevent mite contamination, the rearing rooms are emptied
after each use, cleaned with household ammonia, and heated to about 49°C for 2 days to
kill the mites.
DISCUSSION
Various modifications made to improve on a system to mass-rear the codling moth at
Yakima has resulted in improved production efficiency. The desired environmental con-
ditions in the oviposition cabinet can now be controlled and maintained, and the moth
scale hazard has been removed. The advantages of surface-sterilizing eggs with formalde-
hyde fumes over dipping them in sodium hypochorite or formaldehyde include not only a
reduction of worker exposure to these hazardous chemicals, but also about a 50% reduc-
tion in handling time. Further reduction in worker exposure to moth scales has been
achieved with the scale removal system in the adult collection room, and the use of dis-
posable adult eclosion containers. The cost of disposable adult eclosion containers is
about 35% of the cost of cleaning and sterilizing metal containers, resulting in about a
65% saving.
This system is suitable for obtaining large numbers of selected stages of the codling
moth required for such research as quarantine treatments and studies on pheromones,
attractants, biological control, and pesticides. Eggs can be readily obtained from egg-
laden waxed paper or polystyrene pellets, larvae from the formulated diet, mature cocoon-
ing larvae or pupae from the pupation strips, and adults from collection containers. Large
numbers of infested immature apples can also be produced by this system. Since 1983, we
have successfully produced up to 32,000 larvae per week on the formulated diet.
ACKNOWLEDGEMENTS
We thank Lee Fox, Eric Halfhill (retired), John Turner and Pat Wilson of this insehnnae
for their technical assistance. This study was funded in part by the Washington State Tree
Fruit Research Commission.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 OF
REFERENCES CITED
Chew, V. and M. T. Ouye. 1985. Statistical basis for quarantine treatment schedule and security, p. 70-74. In
Moy, J. H. [ed.], Radiation Disinfestation of Food and Agricultural Products. Hawaii Institute Tropical
Agric. and Human Resources, Honolulu, Hawaii.
Hamilton D. W. and D. O. Hathaway. 1966. Codling moths, p. 339-354. In Smith, C. N. [ed.], Insect
Colonization and Mass Production, Academic Press, Inc., New York.
Hathaway, D. O. 1967. Inexpensive cardboard trays for mass rearing codling moth. J. Econ. Entomol. 60: 888-
889.
Hathaway, D. O., L. G. Schoenleber and L. V. Lydin. 1972. Codling moths: plastic pellets or waxed paper as
oviposition substrates. J. Econ. Entomol. 65: 1756-1757.
Howell, J F. 1967. Paraffin films to control dehydration of an artificial rearing medium for codling moth. J.
Econ. Entomol. 60: 289-290.
1970. Rearing the codling moth on an artificial diet. J. Econ. Entomol. 63: 1148-1150.
1971. Problems involved in rearing the codling moth on diet in trays. J. Econ. Entomol. 64: 631-636.
1972. Rearing the codling moth on a soya, wheat germ starch medium. J. Econ. Entomol. 65: 636-637.
Hutt, R. B., L. D. White, L. G. Schoenleber and R. E. Short. 1972. Automatic collection of mass-reared codling
moths by phototaxis response and a chilled environment. J. Econ. Entomol. 65: 1525-1527.
Compound eye of male Stylops pacifica
(Strepsiptera; Stylopidae)
H.R. MacCARTHY
ADJUNCT PROFESSOR, DEPARTMENT OF BIOLOGICAL SCIENCES,
SIMON FRASER UNIVERSITY, BURNABY, BRITISH COLUMBIA, VSA 186
INTRODUCTION
Few insect groups have greater sexual dimorphism than the Strepsiptera. With the excep-
tion of a single family (Mengeidae), the female is a completely passive endoparasite in a
much larger insect, and nearly without the ususal external features of other insects
(Gehrhardt 1939). These are reduced to a hint of segmentation on the abdomen and a few
indeterminate pits and sutures on the sclerotized cephalothorax (Fig. 1). Copulation is
said to be achieved in situ (Bohart 1941).
The male develops in a larval capsule similar to that of the female, but upon emer-
gence is a small, unusually active, winged insect, about 3 mm long, already well sclero-
tized, short-lived and nervous, having many of its structures much modified. The anten-
nae show development and variation between species and are well provided with large
sensoria (Fig. 2).
The compound eyes of adult males appear to be somewhat primitive and are possibly
of secondary importance to the insect. They resemble the eyes of thrips, collembolans,
male coccids or the pupal eyes of some beetles (Pankrath 1890). There are no ocelli.
Strohm (1910) suggested that each facet represents a lateral ocellus (ocellare komplexau-
gen), but Bohart (1941) pointed out that they may equally well have been reduced to their
present form from normal compound eyes. Each optic unit resembles an ocellus rather
than an ommatidium.
METHODS AND MATERIALS
Dr. J.W. McSwain, Instructor in Entomology at the University of California, Berkeley,
caught and identified the insects as Stylops pacifica Bohart. He allowed me to accompany
him into the hills above and behind the town on a fine afternoon in mid-March, 1951. We
took eight bees (Andrena complexa Vier.) feeding on Ranunculus. All were parasitized
with Strepsiptera, five with females including one bee with two, and three with males.
One male was in the act of emerging. The material for study was put alive into
Petrunkevitch fixer and held for a few weeks. The emergent male was the principal
subject.
28 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
MANDIBLE
FUSED
CEPHALOTHORAX
LEVEL OF EMERGENCE
FROM BEE
SHADOW CAUSED BY
BROOD CANAL
DISTORTION CAUSED BY
CONTACT WITH INTERNAL
ORGANS OF BEE
DISTENTION CAUSED BY
DEVELOPING OVA
t imm ,
length approx. 4.0 mm.
wiath approx. 1.8 mm.
Figure 1. Adult female S. pacificia. Ventral aspect.
~~ APPROX.
PLANE OF
SECTION
OPTIC
SUTURE
width of head = 1.44 mm
Figure 2. Head of adult male S. pacifica, showing compound eyes and antennae with sensoria.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 29
PROTECTIVE HAIRS
BETWEEN LENSES
OPTIC UNIT ENLARGED
BELOW
INTEGUMENT SPLIT
BY MICROTOME
OPTIC UNITS CUT ON AN
ANGLE
OPTIC SUTURE
PIGMENTED EPIDERMAL
CELLS
CRYSTALLINE BODY
Figure 3. Compound eye of adult male S. pacifica, showing the separation of optic units (a) and
detail of a single unit (b).
The histological treatment was unspecialized, designed to stain and counterstain as
many cell types as possible. Dehydration and embedding started with ethyl alcohol from
70%, increased in five stages to 100%, each stage for 4 h, followed by three changes of
xylene at various intervals. Paraffin was added to semi-fluidity and heated to 70°C for 4 h,
then infiltrated further fresh paraffin for 2 h at 70°C in a vacuum chamber. The sections
were cut transversely from the tip of the abdomen forward. Tests showed that haemo-
toxylin of pH 1.5 in 80% alcohol gave good results. The eosin stain was in 95% alcohol,
at pH 7.0. The sections were never hydrated below 80% alcohol, and were mounted in
Canada balsam.
RESULTS AND DISCUSSION
The head of the male S. pacifica is so wide in proportion to its length that the hemispheri-
cal compound eyes appear to be stalked (Fig. 2). Each eye has a deeply inflected optic
suture (Figs. 2, 3, & 4). There are between 50 and 80 lenses per eye, which are not hexag-
onal but circular, glabrous, protuberant and well separated from one another by thickly
pilose, heavily-pigmented integument (Fig. 4). The irregular biconvex shape of the lens
suggests that these coarse hairs may play some part in shading it from oblique light rays
(Figs. 3a & 5a,b), on the assumption that axial rays are the most important.
Within the lens a number of striae can be seen, a result of its laminar construction
(Snodgrass 1935). These probably alter the refractive index of the lens, thus making it
more difficult to work out a reliable optical scheme. A thick lens of this shape would have
two principal points, the distances of which from their associated surfaces would depend
upon the lens thickness, refractive index and both radii of curvature (Hausmann and Slack
1939). Using a single focal point a hypothetical optical system is proposed (Fig. 5b),
which agrees with the interpretations of the tissues and their apparent functions.
30 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
BICONVEX LENS
OPTIC SUTURAL
INFLECTION
GLOBULAR CELLS
OPTIC NERVE
BASEMENT MEMBRANE
LAMINAR
GANGLION
BASEMENT MEMBRANE
RESUMES NORMAL
FUNCTION
OPTIC UNIT
SHOWING DETAIL
GLOBULAR CELLS
PROTECTIVE HAIRS
THICK, DENSE
INTEGUMENT
0.1 mm
Figure 4. Compound eye of adult male S. pacifica, in lateral cross-section.
According to the lens formula, 1/p + 1/q = 1/f (where p = object distance, q = image dis-
tance, and f = focal length) and substituting values taken from the drawings, the object
distance is found to be short. Male S. pacifica appear to be short-sighted.
Immediately beneath the integument in the specimen studied, each otic unit was sur-
rounded by about 11 pigmented epidermal cells to a depth of three or four cells, or 30-40
cells per optic unit (Figs. 3a, b). At this level the units abut on one another in convention-
al, slightly irregular, hexagons. Beneath the lens and surrounded by the epidermal cells is
a transparent crystalline body, apparently non-cellular, which may be formed as a secre-
tion product of other cells (Snodgrass 1935). Below this again is a circle of granular, pig-
mented, corneagenous epithelium, without cell boundaries (Fig. 5a).
From this point proximally around the base of the unit, the cells change to rhab-
domeres, or optic sense cells, with processes passing into the brain. There appear to be
about 50 rhabdomeres per unit. There was not enough resolution to observe any neurofib-
rillae on the walls of the cells facing the retinal lumen (Hesse 1901). The lumen is non-
nuclear with a fine-textured and variable darkening in the centre (Figs. 4 and 5a). The
proximal processes of the rhabdomeres, or optic nerves, are prominent, each converging
upon and passing through the basement membrance by way of a large opening. Around
the base of each optic unit are apparently unspecialized mantle cells which may have no
more than a nutritive or parenchymatous role.
The essentially epidermal nature of the eye is shown where the basement membrance
(Figs. 4 and 5) passes directly to the integument. at the optic sutural inflection (Fig. 4),
there to resume its normal function underlying the epidermis. Within the brain there is a
wide zone lying immediately beneath the basement membrane and traversed by the optic
nerves, intersspersed with large globular cells (Fig. 4). A laminar ganglion follows proxi-
mally, succeeded by other brain tracts. No optic chiasma was seen.
NOTES
This study was an individual assignment in a course on morphology, given by Prof. Roderick Craig, when I was
a student at the University of California at Berkeley, in 1951. It has been slightly edited and shortened.
According to the late Prof. G.J. Spencer (Proc. Ent. Soc. B.C. 48: 38, 1951), the late Hugh Leech “found sty-
lopized bees freely in the arboretum” on the UBC campus. I know of no other mention in this province of these
extraordinary insects.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 31
PARALLEL RAYS
HAIRS PROTECTING
LIGHT-PROOF FROM SIDE RAYS
INTEGUMENT
PRINCIPAL FOCUS LENS
DIVERGING RAYS
RETINAL CELLS
rele ap eth = OPTIC NERVE
BICONVEX
CORNEAL LENS —— PROTECTIVE HAIR
mm ._ INTEGUMENT
i
o> @———_— EPIDERMAL CELL
me! CRYSTALLINE BODY
CORNEAGENOUS
PIGMENTED
EPIDERMAL
CELLS
BOUNDARIES
NON-NUCLEAR
RETINAL LUMEN
RHABDOMERE,
OR OPTIC SENSE
CELL
: ci PROXIMAL
MANTLE CELL WU U fe PROCESSES OF
f Ame OPTIC SENSE
BASEMENT CELLS
MEMBRANE
Figure 5. Compound eye of adult male S. pacifica. Longitudinal sections of two adjacent optic units
(a) and theoretical optical system (b).
REFERENCES
Bohart, R.M. 1941. A revision of the Strepsiptera with special reference to the species of North America. Univ.
Calif. Pub. in Ent. 7(6): 91-160 (Plate 3, 8 Figs.).
Gehrhardt, E.E. 1939. The morphology of the adult female Stylops pacifica Bohart, (Strepsiptera, Kirby).
Unpublished M.S. thesis in library, Univ. Calif., Berkeley.
Hausmann, E.E. and E.P. Slack. 1939. Physics. Van Nostrand, New York, 2nd ed.
Hesse, R. 1901. Untersuchungen iiber die Organe der Lichtenpfindung bei niederen Thieren. VHT. Von den
Arthropoden-Augen. Zeitschr. wiss. Zool. 70: 347-473.
Pankrath, O. 1890. Das Auge der Raupen and Phryganidenlarven. Zeitschr. wiss. Zool. 49: 670-708.
(Illustrations only).
Snodgrass, R.E. 1935. Principles of Insect Morphology. McGraw-Hill, New York and London, Ist ed.
Strohm, K. 1910. Die Zusammengesetzten Augen der Mannchen von Xenos rossi. Zool. Anz. 36:156-159.
Larvae of Hyalophora euryalus kasloensis
(Lepidoptera: Saturniidae)
W.D. MOREWOOD
DEPARTMENT OF BIOLOGY, UNIVERSITY OF VICTORIA
VICTORIA, B.C. V8W 2Y2
There are no currently recognized subspecies of the ceanothus silkmoth, Hyalophora
euryalus (Boisduval) (cf. Ferguson 1972, Lemaire 1978; see Packard 1914, McDunnough
1921 for discussion of specific synonyms); however, the status of H. e. kasloensis
(Cockerell) has been debated for many years. The subspecific name kasloensis was pub-
lished by T.D.A. Cockerell in Packard’s (1914) monograph and was described as repre-
senting “‘a local [submelanic] race occurring in the interior of British Columbia” which
was originally described, but not named, by Cockle (1908). Based on surveys of wild
32 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
moths and some very limited hybridization studies, Sweadner (1937) concluded that H. e.
kasloensis represented an intergrade population between H. euryalus, native to the Pacific
coast and western mountains, and H. gloveri (Strecker), native to the Rocky Mountain
region. It has since been well-established that interspecific crosses in the genus
Hyalophora Duncan produce hybrids consisting of fertile males and sterile females
(Collins 1973). This fact, combined with the apparently intermediate characters of adult
H. e. kasloensis, led Ferguson (1972) to speculate that H. e. kasloensis arose through a
period of hybridization between H. euryalus and H. gloveri with extensive backcrossing
of hybrid males to H. euryalus females, resulting in a population that is essentially H.
euryalus but that retains enough of the H. gloveri gene pool to produce a distinct form. He
concluded by reducing the name kasloensis to the status of a synonym of H. euryalus, but
not before noting that the larva of H. e. kasloensis “has never been adequately described”’.
The existence of a distinct larval phenotype in H. e. kasloensis has long been suspected
(Sweadner 1937, Collins and Weast 1961, Collins 1984) but has never been documented.
In May 1988 a small colony of H. e. kasloensis was established from an adult female
collected at Kelowna, B.C., and larvae were reared on cuttings of redstem ceanothus,
Ceanothus sanguineus Pursh (Rhamnaceae), under ambient conditions in the Okanagan
Valley. The colony was maintained and enlarged by mating several reared females with
wild males at Kelowna in 1989 and at OK Falls in 1990 using mating cages constructed
from coffee cans, as described by Miller and Cooper (1976). Larvae were reared on C.
sanguineus cuttings in the Okanagan during the summer of 1989 and on cuttings of cas-
cara, Rhamnus purshiana DC. (Rhamnaceae), and Douglas-fir, Pseudotsuga menziesii
(Mirb.) Franco var. menziesii, in Victoria during the summer of 1990. Cascara was chosen
as an alternate food plant because of its relationship to ceanothus and because it is quite
common around Victoria whereas ceanothus is very scarce on Vancouver Island.
Douglas-fir was offered as a food plant because H. euryalus larvae have been found local-
ly in Douglas-fir seed orchards. A series of specimens (eggs and neonate through 5th
instar larvae) from the 1990 generation was deposited at the Royal British Columbia
Museum [catalogue numbers ENT991-64042 through ENT991-6405 1].
The species was initially identified as H. euryalus based on the collection locality, the
wing patterns of the adults, and the apparent preference of the larvae for ceanothus as a
food plant. Eventually, however, it became obvious that the larvae did not match pub-
lished descriptions for larvae of H. euryalus, in which all of the dorsal scoli in 4th and Sth
instars are bright yellow (cf. Amett and Jacques 1981). The reared larvae had red-orange
dorsal scoli (Plate 1), with no discernable variation in this character among any of the ca.
250 larvae reared during the past three years. This larval phenotype is distinct from both
A. euryalus, in which the dorsal scoli are yellow, and H. gloveri, in which the dorsal scoli
are red-orange in 4th instar but yellow in 5th instar larvae (Ferguson 1972). It is also note-
worthy that the form of the dorsal scoli in 5th instar larvae resembles more closely that of
H. euryalus than that of H. gloveri (cf. Tuskes 1976).
H. e. kasloensis shows many characters that are intermediate between H. euryalus and
H. gloveri, particularly in adult wing patterns, and may well have originally arisen
through hybridization between these two species as proposed by Ferguson (1972).
However, the fact that the larvae show a phenotype that is different from both of the sup-
posed parental species suggests that this form should be considered distinct, particularly
when dorsal scoli colouration is used as the primary diagnostic character for distinguish-
ing species in larvae of Hyalophora (cf. Ferguson 1972). The name H. e. kasloensis
seems appropriate because of its apparent affinities with H. euryalus and the fact that the
specimen designated as lectotype was collected at Kaslo, B.C. (Ferguson 1972). Further
studies, involving cross-breeding with H. euryalus and H. gloveri as well as surveys of
the geographic range of the H. e. kasloensis phenotype, are required to firmly establish
the taxonomic status of this distinct form of Hyalophora.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 53
Plate 1. Late 4th (top) and early Sth (bottom) instar larvae of Hyalophora euryalus kasloensis
(Cockerell) (Lepidoptera: Saturniidae) on Ceanothus sanguineus Pursh (Rhamnaceae), July 1989.
ACKNOWLEDGEMENTS
Thanks to T.J. Simonson for invaluable assistance in collecting adults and rearing larvae
in 1988 and 1989, and to M. Gardiner for mating adults and collecting their eggs in the
spring of 1990. Special thanks to H.W. Morewood for providing financial support for this
publication.
REFERENCES
Arnett, R.H. Jr. and R.L. Jacques, Jr. 1981. Simon and Schuster’s Guide to Insects. Simon and Schuster, New
York. entry 246.
Cockle, J.W. 1908. Samia rubra. Entomol. News 19:340-341.
Collins, M.M. 1973. Notes on the taxonomic status of Hyalophora columbia (Saturniidae). J. Lepid. Soc.
27:225-235.
Collins, M.M. 1984. Genetics and ecology of a hybrid zone in Hyalophora (Lepidoptera: Saturniidae). Univ.
Calif. Publ. Entomol. 104, University of California Press, Berkeley. p. 27.
Collins, M.M. and R.D. Weast. 1961. Wild Silk Moths of the United States. Collins Radio Company, Cedar
Rapids, Iowa. p. 20.
Ferguson, D.C. in Dominick, R.B. et al. 1972. The Moths of America North of Mexico, fasc. 20.2B,
Bombycoidea (in part). pp. 243-267.
Lemaire, C. 1978. The Attacidae of America. Attacinae. Edition C. Lemaire, 42 Boulevard Victor Hugo,
Neuilly-sur-Seine, France. pp. 114-125.
McDunnough, J. 1921. Samia euryalus Bdv., the correct name for the Californian silk worm moth. Can.
Entomol. 53:191-192.
Miller, T.A. and W.J. Cooper. 1976. Portable outdoor cages for mating female giant silkworm moths
(Saturniidae). J. Lepid. Soc. 30:95-104.
Packard, A.S. 1914. Monograph of the Bombycine Moths of North America, Part III. Mem. Nat. Acad. Sci.
12:224-226.
Sweadner, W.R. 1937. Hybridization and the phylogeny of the genus Platysamia. Ann. Carnegie Mus. 25:163-
242.
Tuskes, P.M. 1976. A key to the last instar larvae of west coast Saturniidae. J. Lepid. Soc. 30:272-276.
34 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
cis-Verbenol: An aggregation pheromone for the mountain
pine beetle, Dendroctonus ponderosae Hopkins
(Coleoptera: Scolytidae)
DANIEL R. MILLER
CENTRE FOR PEST MANAGEMENT
DEPARTMENT OF BIOLOGICAL SCIENCES
SIMON FRASER UNIVERSITY
BURNABY, BRITISH COLUMBIA VS5A 186 CANADA
AND
JEAN P. LAFONTAINE
PHERO TECH INC. 7572 PROGRESS WAY, RR 5
DELTA, BRITISH COLUMBIA
V4G 1E9 CANADA
ABSTRACT
cis-Verbenol increased catches of male mountain pine beetles, Dendroctonus ponderosae
Hopkins, to multiple-funnel traps baited with myrcene and exo-brevicomin. cis-Verbenol had
no effect on the response of males to traps baited with myrcene, exo-brevicomin and
trans-verbenol. In contrast, cis-verbenol increased catches of female D. ponderosae to
semiochemical-baited traps irrespective of the absence or presence of trans-verbenol. Our
results demonstrate that cis-verbenol is an aggregation pheromone for D. ponderosae and
that the combination of cis- and trans-verbenol elicits sex-specific responses.
Additional keywords: trans-verbenol, myrcene, exo-brevicomin, sex-specificity.
INTRODUCTION
Various studies on the use of semiochemicals by the mountain pine beetle, Dendroctonus
ponderosae Hopkins (Coleoptera: Scolytidae), including some that were specifically
aimed at determining the effect of trans-verbenol, inadvertantly used trans-verbenol con-
taminated with 6-20 % cis-verbenol (Pitman 1971; Billings et al. 1976; Ryker and
Rudinsky 1982; Borden er a/. 1983; Conn et al. 1983). The role of trans-verbenol as a
pheromone for D. ponderosae has subsequently been verified with chemical purities
>97% (Ryker and Rudinsky 1982; Libbey et a/. 1985; Borden et al. 1987).
However, no attempt has been made to discern the role of cis-verbenol in the chemical
ecology of D. ponderosae and interpretation of studies using contaminated trans-verbenol
must therefore be suspect. The issue is of economical importance since D. ponderosae is
a major pest of lodgepole pine in the Pacific northwest (Safranyik et al. 1974; Furniss and
Carolin 1980). Semiochemical-based manipulation of D. ponderosae has become a major
component of lodgepole pine silviculture in British Columbia (Borden and Lacey 1985)
Due to production costs, the tree bait most commonly used against D. ponderosae con-
tains a 13:87 mix of cis- and trans-verbenol (Phero Tech Inc., Delta BC), together with
myrcene and exo-brevicomin. Dendroctonus ponderosae uses myrcene as a kairomone
(Billings et al. 1976; Conn et al. 1983; Libbey et al. 1985; Borden et al. 1987) and both
enantiomers of exo-brevicomin as male-produced pheromones (Pitman et al. 1969;
Rudinsky et al. 1974; Pitman et al. 1978; Borden et al. 1983; Libbey et al. 1985; Borden
et al. 1987).
Our objective was to demonstrate that cis-verbenol is an aggregation pheromone for D.
ponderosae in stands of lodgepole pine. cis-Verbenol is produced by D. ponderosae
(Pitman et al. 1969; Hughes 1973; Ryker and Rudinsky 1982; Libbey ef al. 1985; Pierce
et al. 1987; Hunt et al. 1989). Antennae of both sexes of D. ponderosae are sensitive to
cis- and trans-verbenol equally (Whitehead 1986; Whitehead et al. 1989). It is quite
probable, therefore, that cis-verbenol is a pheromone for D. ponderosae. We tested the
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 B35
two following hypotheses: 1) cis-verbenol should increase attraction of D. ponderosae to
traps baited with myrcene and exo-brevicomin; and 2) cis- and trans-verbenol should
have an additive effect on the attraction of D. ponderosae.
MATERIALS AND METHODS
cis-Verbenol was prepared by reduction of S-(-)-verbenone by the alkoxy-substituted
lithium aluminum hydride method (Brown and Deck 1965) and concentrated in vacuo.
trans-Verbenol was prepared by subjecting cis-verbenol to acid-catalysed isomerisation
at 23 °C (Cooper et al. 1967) and purified by flash chromatography on silica gel (Still ef
al. 1978). Chemical and optical purities of verbenols were determined by split, capillary,
gas chromatography (Hewlett Packard HP 5890 using a 30-m X 0.32-mm ID DB-1 fused
silica column), before and after derivatisation to acetyl lactate diastereomers (Slessor et
al. 1985). The chemical purities of cis- and trans-verbenol were 97 and 99%, respective-
ly, while the chiral ratios were identical at 83% S-(-): 17% R-(+).
Verbenol lures consisted of polyethylene, bubble-cap devices (Phero Tech Inc., Delta
BC) containing 1,3-butanediol solutions of cis- and trans-verbenol, respectively. The
release rates of cis- and trans-verbenol were approximately 3.38 and 2.58 mg/day at 24-
27 °C (determined by weight loss). Phero Tech Inc. (Delta BC) supplied the following
additional lures: 1) (+)-exo-brevicomin (chemical purity, 98%) laminar lures ; and 2)
B-myrcene (chemical purity, 98%) in closed, polyethylene, screw-cap bottles (15 mL).
The release rates of exo-brevicomin and myrcene were approximately 0.01 and 281
mg/day, respectively, at 24 °C (determined by collection of volatiles on Porapak-Q for
exo-brevicomin and by weight loss for myrcene).
Forty, 8-unit, multiple-funnel traps (Lindgren 1983) (Phero Tech Inc., Delta BC) were
set in 10 replicate grids of 2 x 2 in stands of mature lodgepole pine near Princeton BC.
Grids were spaced at least 100 m apart, and traps were set 10-15 m apart within each
replicate. Each trap was suspended between trees by rope so that the top funnel of the trap
was 1.3-1.5 m above ground. No trap was within 2 m of any tree. All traps were set during
the period of 2 to 26 September 1989. Treatments were randomly assigned within each
replicate. The control treatment consisted of myrcene and exo-brevicomin while the
remainder consisted of myrcene, exo-brevicomin and one of the following: 1) cis-ver-
benol; 2) trans-verbenol; 3) cis- and trans-verbenol. Sexes in subsamples (N=20) of
tured D. ponderosae were determined by dissection and internal examination of genitalia.
The data were analysed using the SAS statistical package ver. 5.0 (SAS Institute Inc.,
Cary NC). For each sex, trap catch data, transformed by In(Y+1), were subjected to 3-
way ANOVA, using replicate, cis-verbenol, frans-verbenol, and the interaction of cis-
and trans-verbenol, as model factors. Two orthogonal contrasts were performed on each
data set, comparing catches in traps baited with myrcene and exo-brevicomin against
catches to traps baited with myrcene, exo-brevicomin and cis-verbenol and catches to the
combination of myrcene, exo-brevicomin and frans-verbenol against catches to traps bait-
ed with all four components.
RESULTS AND DISCUSSION
Both cis- and trans-verbenol significantly increased the catches of D. ponderosae to
semiochemical-baited funnel traps (Figs. | and 2), although the effect of cis-verbenol on
females was only weakly significant. There was a significant interaction between cis- and
trans-verbenol on the capture of male D. ponderosae (Fig. 1). Catches of males in traps
baited with myrcene, exo-brevicomin and trans-verbenol were not significantly different
from catches in traps baited with all four components (orthogonal contrast, F(1,35),
P=0.750). Catches of males in traps baited with myrcene, exo-brevicomin and cis-ver-
benol were significantly higher than those in traps baited with myrcene and exo-brevi-
comin alone (orthogonal contrast, F(1,35), P=0.004). In contrast, there was no interaction
between cis- and trans-verbenol on the catches of female D. ponderosae (Fig. 2).
36 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
ANOVA
M+eB Source df Pp
A 9 0.651
per ere B 20.00
M+eB +tV C 1: O2058
BC... te - 02018
0 20 40
Mean (+SE) percentage of males
captured per replicate
Figure 1. The effects of cis- (cV) and trans-verbenol (tV) on the attraction of male D. ponderosae
to multiple-funnel traps baited with myrcene (M) and exo-brevicomin (eB) near Princeton BC from
2 to 26 September 1989 (n=10). Data were transformed by In(Y+1) and subjected to ANOVA
using the following model factors: replicate (A), cis-verbenol treatment (B), trans-verbenol treat-
ment (C), and the interaction between cis- and trans-verbenol treatments (B*C). The total number
of males caught was 2303.
ANOVA
M+eB Source df P
A 9 0.001
Meda aHe B+ lore OG
M+eB +tV C 1 0.089
BC 1 6884
M+ eB +cV+tV Error 26
0 20 40
Mean (+SE) percentage of
females captured per replicate
Figure 2. The effects of cis- (cV) and trans-verbenol (tV) on the attraction of female D. ponderosae
to mutiple-funnel traps baited with myrcene (M) and exo-brevicomin (eB) near Princeton BC from
2 to 26 September 1989 (n=10). Data were transformed by In(Y+1) and subjected to ANOVA using
the following model factors: replicate (A), cis-verbenol treatment (B), trans-verbenol treatment (C),
and the interaction between cis- and trans-verbenol treatments (B*C). The total number of females
caught was 5303.
Our results demonstrate that cis-verbenol is an aggregation pheromone for D. pon-
derosae. \t is produced by female D. ponderosae (Pitman et al. 1969; Hughes 1973;
- Ryker and Rudinsky 1982; Libbey et al. 1985; Pierce et al. 1987) and is attractive to both
sexes (Figs. 1 and 2). Interpretations of results from previous studies that used trans-ver-
benol, with chemical purities less than 97%, should consider the effect of cis-verbenol,
and the possible interactions of cis-verbenol with other treatments.
Our results further show that cis- and trans-verbenol have an additive effect on the
attraction of female D. ponderosae but not on male D. ponderosae. The interaction
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 37
between the verbenols resulted in sex-specific responses; males and females responded
differently to cis- and trans-verbenol separately than to the combination of verbenols
(Figs. 1 and 2). These sex-specific responses may be a function of either the presence of
both verbenols together or of the ratio of verbenols. The ratio of cis- and trans-verbenol
following autoxidation of O-pinene ranges from 29:71 to 20:80 (Hunt et al. 1989).
Axenically-reared D. ponderosae produce verbenol with a cis:trans ratio of 14:86 when
exposed to a-pinene odors while wild beetles produce a ratio of 2:98 (Hunt ef al. 1989).
Regardless of the mode of specificity, both cis- and trans-verbenol are required to
maximise the attraction of female D. ponderosae. Since females initiate attacks on trees
(Safranyik et al. 1974), it is critical that tree baits used in silvicultural practices to control
populations of D. ponderosae contain both pheromones . Fortunately the bait currently
employed operationally for controlling D. ponderosae contains both cis- and trans-ver-
benol at a ratio of 13:87 (Phero Tech Inc., Delta BC), well within the range of observed
production ratios.
ACKNOWLEDGEMENTS
We thank T.C. Baker, J.H. Borden, B.S. Lindgren and three anonymous reviewers for
critical reviews of the manuscript. Assistance in the manufacture of release devices was
kindly provided by Phero Tech Inc., Delta BC. Voucher specimens of D. ponderosae
have been deposited at the Entomology Museum at Simon Fraser University, Burnaby
BC. This research was supported in part by the Natural Sciences and Engineering
Research Council of Canada (Operating Grant No. A3881 and Strategic Grant No.
G1611), and the Science Council of British Columbia [Grant No. 1(RC 14-16)].
REFERENCES
Billings, R.F., R.I. Gara and B.F. Hrutfiord. 1976. Influence of ponderosa pine resin volatiles on the response of
Dendroctonus ponderosae to synthetic trans-verbenol. Environ. Entomol. 5: 171-179.
Borden, J.H. and T.E. Lacey. 1985. Semiochemical-based manipulation of the mountain pine beetle,
Dendroctonus ponderosae Hopkins: A component of lodgepole pine silviculture in the Merritt timber sup-
ply area of British Columbia. Z. ang. Ent. 99: 139-145.
Borden, J.H., J.E. Conn, L.M. Friskie, B.E. Scott, L.J. Chong, H.D. Pierce, Jr., and A.C. Oehlschlager. 1983.
Semiochemicals for the mountain pine beetle, Dendroctonus ponderosae (Coleoptera: Scolytidae), in British
Columbia: Baited tree studies. Can. J. For. Res. 13: 325-333.
Borden, J.H., L.C. Ryker, L.J. Chong, H.D. Pierce, Jr., B.D. Johnston and A.C. Oehlschlager. 1987. Response of
the mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Scolytidae), to five semiochemi-
cals in British Columbia lodgepole pine forests. Can. J. For. Res. 17: 118-128.
Brown, H.C. and H.R. Deck. 1965. Selective reductions. VUI. The stereochemistry of reduction of cyclic and
bicyclic ketones by the alkoxy-substituted lithium aluminum hydrides. J. Am. Chem. Soc. 87: 5620-5624.
Conn, J.E., J.H. Borden, B.E. Scott, L.M. Friskie, H.D. Pierce, Jr., and A.C. Oehlschlager. 1983.
Semiochemicals for the mountain pine beetle, Dendroctonus ponderosae (Coleoptera: Scolytidae) in British
Columbia: Field trapping studies. Can. J. For. Res. 13: 320-324.
Cooper, M.A., J.R. Salmon and D. Whittaker. 1967. Stereochemistry of the verbenols. J. Chem. Soc. (B) 1967:
1259-1261.
Furniss, R.L. and V.M. Carolin. 1980. Western forest insects. U.S.D.A. For. Serv. Misc. Publ. 1339.
Hughes, P.R. 1973. Effect of Ol-pinene on frans-verbenol synthesis in Dendroctonus ponderosae Hopk.
Naturwiss. 60: 261-262.
Hunt, D.W.A., J.H. Borden, B.S. Lindgren and G.Gries. 1989. The role of autoxidation of pinene in the produc-
tion of pheromones of Dendroctonus ponderosae (Coleoptera: Scolytidae). Can. J. For. Res. 19: 1275-1282.
Libbey, L.M.. L.C. Ryker and K.L. Yandell. 1985. Laboratory and field studies of volatiles released by
Dendroctonus ponderosae Hopkins (Coleoptera, Scolytidae). Z. ang. Ent. 100: 381-392.
Lindgren, B.S. 1983. A multiple-funnel trap for scolytid beetles. Can. Ent. 115: 299-302.
Pierce, H.D., Jr., J.-E. Conn, A.C. Oehlschlager and J.H. Borden. 1987. Monoterpene metabolism in female
mountain pine beetles, Dendroctonus ponderosae Hopkins, attacking ponderosa pine. J. Chem. Ecol. 13:
1455-1480.
Pitman, G.B. 1971. trans-Verbenol and alpha-pinene: Their utility in manipulation of the mountain pine beetle.
J. Econ. Ent. 64: 426-430.
Pitman, G.B., M.W. Stock and R.C. Knight. 1978. Pheromone application in mountain pine beetle - lodgepole
pine management: Theory and practice, pp. 165-173. Jn A.A. Berryman, G.D. Amman and R.W. Stark
(eds.). Theory and practice of mountain pine beetle management in lodgepole pine forests. College of Forest
Resources, University of Idaho, Moscow ID.
38 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
Pitman, G.B., J.P. Vité, G.W. Kinzer and A.F. Fentiman, Jr. 1969. Specificity of population-aggregating
pheromones in Dendroctonus. J. Insect Physiol. 15: 363-366.
Rudinsky, J.A., M.E. Morgan, L.M. Libbey and T.B. Putnam. 1974. Antiaggregation-rivalry pheromone of the
mountain pine beetle. Environ. Entomol. 3: 90-98.
Ryker, L.C. and J.A. Rudinsky. 1982. Field bioassay of exo- and endo-brevicomin with Dendroctonus pon-
derosae in lodgepole pine. J. Chem. Ecol. 8: 701-707.
Safranyik, L., D.M. Shrimpton and H.S. Whitney. 1974. Management of lodgepole pine to reduce losses from
the mountain pine beetle. Forestry Canada For. Tech. Rep. 1.
Slessor, K.N., G.G.S. King, D.R. Miller, M.L. Winston and T.L. Cutforth. 1985. Determination of chirality of
alcohol or latent alcohol semiochemicals in individual insects. J. Chem. Ecol. 11: 1659-1667.
Still, W.C., M. Kahn and A. Mitra. 1978. Rapid chromatographic technique for preparative separations with
moderate resolution. J. Org. Chem. 43: 2923-2925.
Whitehead, A.T. 1986. Electroantennogram responses by mountain pine beetles, Dendroctonus ponderosae
Hopkins, exposed to selected semiochemicals. J. Chem. Ecol. 12: 1603-1621.
Whitehead, A.T., D.T. Scott, R.F. Schmitz and K. Mori. 1989. Electroantennograms by mountain pine beetles,
Dendroctonus ponderosae Hopkins, exposed to selected chiral semiochemicals. J. Chem. Ecol. 15: 2089-
2099.
Melanchra picta (Harris) (Lepidoptera: Noctuidae),
a cutworm new to British Columbia
SHEILA M. FITZPATRICK and JAMES T. TROUBRIDGE!’
AGRICULTURE CANADA RESEARCH STATION,
6660 N.W. MARINE DRIVE, VANCOUVER, B. C., CANADA V6T 1X2
1. ORDER OF AUTHORS DECIDED BY TOSS OF A COIN.
Here we report the occurrence of the zebra caterpillar, Melanchra picta (Harris) as a
minor pest of commercial cranberries, Vaccinium macrocarpon Ait., in Langley and Pitt
Meadows, British Columbia, during the summer of 1991. In the field, zebra caterpillars
ate the growing tips of cranberry runners and uprights. In the laboratory, larvae preferred
succulent cranberry tissue, consuming mature leaves only if no new growth remained. In
the field and laboratory, larvae also consumed the foliage of dicotyledonous weeds such
as cutleaf blackberry, Rubus laciniatus Willd., western St. John's wort, Hypericum formo-
sum Humboldt, marsh St. John's wort, Triadenum virginicum L., and Watson's willow
herb, Epilobium watsonii Barbey. In eastern Canada, zebra caterpillars have been report-
ed to feed on a wide variety of fruit, vegetable, and leguminous forage crops (Beirne,
1971).
Early records of zebra caterpillar infestations in British Columbia (Cockle, 1911;
Middleton, 1913) actually referred to Mamestra canadensis Smith, now considered a syn-
onym of Lacanobia nevadae (Grote). In Canada, the zebra caterpillar, M. picta, occurs
from the Atlantic coast, west to the foothills of the Rocky Mountains, whereas in the
U.S.A. its range extends further west into California, Oregon, and Washington. There are
no specimens of M. picta from B.C. in the Canadian National Collection, the Royal
British Columbia Museum, or the Spencer Collection, University of British Columbia,
nor does M. picta appear on lists of B. C. fauna (e.g. Llewellyn Jones, 1951). Recent
reports of M. picta on strawberries, Fragaria x ananassa Duch., in 1981, highbush blue-
berries, Vaccinium corymbosum L., in 1983 (Belton, 1988), and corn, Zea mays L., in
1990 (Philip, 1991) in B. C. probably refer to this species. Since the zebra caterpillar has
previously been found very close to the B.C. border in Washington State, (Tonasket, 40
km south of Osoyoos, B.C.; Puyallup, 55 km south of Seattle), we believe that its pres-
ence in B. C. represents a recent range extension rather than an introduction.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 39
The zebra caterpillar is not usually a significant pest, but local outbreaks have been
recorded from eastern Canada (Beirne, 1971). The larva has a red head capsule and a
black stripe running down its back. On each side of its body, a black longitudinal stripe,
broken with narrow, white, vertical lines, runs between two bright yellow stripes. M. picta
is bivoltine, with larvae present during late June and July and again in September in the
Fraser Valley. Its presence on cranberries, an economically important crop in B. C., bears
watching.
ACKNOWLEDGMENTS
We thank B. Frazer and D. Raworth for reading the manuscript and offering appreciated
criticism, J. D. Lafontaine, who searched the Canadian National Collection for distribu-
tion records and confirmed our identification, and C. S. Guppy, who searched the Royal
B. C. Museum for distribution records.
REFERENCES
Beirne, B. P. 1971. Pest insects of annual crop plants in Canada. I. Lepidoptera. I]. Diptera. III]. Coleoptera.
Mem. Ent. Soc. Canada 78: 1-124.
Belton, E. M. 1988. Lepidoptera on fruit crops in Canada. Pest management papers. No. 30. Simon Fraser
University. 105 pp.
Cockle, J. W. 1911. Report from the Kootenay District. Proc. B. C. Ent. Soc. 1:13-15.
Llewellyn Jones, J. R. J. 1951. An annotated checklist of the Macrolepidoptera of British Columbia. Ent. Soc.
of B. C. Occasional paper no. |. 148 pp.
Middleton, M. S. 1913. Cutworms and their control. Proc. B. C. Ent. Soc. 3: 36-37.
Philip, H. G. 1991. Insects and related pests of corn: British Columbia, p. 15. /n M. J. Sarazin (ed.), The
Canadian agricultural insect pest review, vol. 68. Agriculture Canada, Research Branch.
Distribution of European winter moth, Operophtera
brumata (L.)', and Bruce spanworm, O. bruceata (Hulst),
in the lower Fraser Valley, British Columbia
SHEILA M. FITZPATRICK» 3, JAMES T. TROUBRIDGE?,
and BARBARA PETERSON?4
1. LEPIDOPTERA: GEOMETRIDAE
2. AUTHOR TO WHOM CORRESPONDENCE SHOULD BE ADDRESSED.
3. AGRICULTURE CANADA RESEARCH STATION,
6660 N.W. MARINE DRIVE, VANCOUVER, B.C. V6T 1X2
4. PRO-TECH CROP PROTECTION, COAST AGRI CROP PRODUCTS,
464 RIVERSIDE ROAD S., R.R. 2, ABBOTSFORD, B.C. V2S 4N2
ABSTRACT
Sixteen pheromone traps, baited with (Z,Z,Z)-1,3,6,9-nonadecatetraene, were placed in com-
mercial blueberry and raspberryfields, and at one woodland site in the lower Fraser Valley.
Traps were monitored weekly from early November, 1990 until late January, 1991. Winter
moth males were recovered from all but the eastern-most trap in Mission. Four traps in blue-
berry fields in Richmond caught a total of 2,928 winter moths, and 198 were caught in two
traps in Delta and Surrey, whereas only 74 came to the ten traps north and east of Surrey. A
total of 1,306 Bruce spanworm males were trapped. Although spanworm moths were recov-
ered from traps in all areas, there was no correlation between trap location and number of
spanworms caught. Thirteen males with characters intermediate between the two species
were trapped in Richmond and Surrey. Males of both species were more numerous in rasp-
berries than in nearby blueberry fields. Spanworm males came to the traps later in the fall
than winter moths. East of Richmond, most spanworm males were trapped during November
whereas, in Richmond, very few were attracted until the first week of December.
40 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
INTRODUCTION
The polyphagous European winter moth, Operophtera brumata (L.), was first detected in
British Columbia in the mid-1970's (Gillespie et al., 1978) and has become a serious pest
of highbush blueberries, Vaccinium corymbosum L., in Richmond, B.C. (Sheppard et al.,
1990). In 1988, the B.C. Blueberry Co-operative Association was forced to cancel over
1.36 million kg in sales (Whaley, 1989) because larval damage to blossoms prevented
entire plantings from producing fruit.
Fruit growers in the lower Fraser Valley east of Richmond are concerned that winter
moths will spread undetected into their area and damage their crops. Although the female
moths are flightless, larvae may be carried by the wind (Edland, 1971) and eggs and lar-
vae can be inadvertently transported on nursery stock. To provide growers east of
Richmond with an early warning system, we used pheromone traps to map the distribu-
tion of the winter moth in the lower Fraser Valley. We were able to detect the Bruce span-
worm as well as the winter moth, because the pheromone isolated from winter moth
females (Roelofs et al., 1982) has also been isolated from spanworm females (Underhill
et al., 1987) and attracts males of both species (Roelofs ef al., 1982; Underhill et ai.,
1987). Here we report the numbers of males of both species attracted to pheromone traps
during November, 1990, to January, 1991, in blueberry-and raspberry-growing areas of
the lower Fraser Valley.
METHODS AND MATERIALS
Pheromone trapping
Sixteen double-cone orifice traps (Hara traps; Hara Products Ltd., Swift Current, Sask.)
were baited with rubber septa impregnated with 100 ug of (Z,Z,Z)-1,3,6,9-nonadecate-
traene, the winter moth pheromone, and placed at field sites on October 31, 1990.
Aninsecticide-containing strip (S.W.A.T. Insect Strip; Green Cross, Ltd.) was placed in
each trap and the trap cones were covered with fine screening to keep birds from eating
dead moths. Single traps were placed in four commercial blueberry fields in the munici-
pality of Richmond (Fig. 1: 1-4), eight commercial blueberry fields from Delta to the
eastern-most site in the municipality of Mission (Fig. 1: 5-9, 14-16) and in three commer-
cial raspberry fields from Langley to Matsqui (Fig. 1: 11-13). One trap was placed in a
mixed coniferous/deciduous forest at least | km away from cultivated land in Langley
(Fig. 1: 10). Traps were emptied weekly from November 6 to December 18, 1990, and
then on January 23 and 30, 1991. Very bad weather prevented us from reaching some of
the sites between late December and mid-January.
Moth identification
Several authors have described external characters (Brown, 1962; Cuming, 1961;
Pivnick, 1988) and genitalic characters (Eidt et a/., 1966; Ferguson, 1978; Wolff, 1964)
of the two moths. To identify specimens accurately, we found it necessary to use a syn-
thesis of these characters plus some previously unreported ones, and to quantify the
dimensions of genitalic characters (Table 1).
Data analysis
Where appropriate, the data were analyzed by Spearman rank correlation or t-test.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 4]
Table 1
Characters used to separate males of the Bruce spanworm, Operophtera bruceata (Hulst), from males of the
European winter moth, Operophtera brumata (L.)
Type of
Character Spanworm Winter moth
External
Wings distinct lines and bands lines on dorsal
on dorsal surfaces forewing are obscure;
often no lines on
dorsal hindwing
Forewing pale yellow-orange yellow-orange colour
ventral costal margin’ faint to absent
Hindwing* dark dorsal discal dot dot absent
Abdomen* golden brown’ brown
Genitalic>
Uncus narrow (< 0.12 mm); wider (ca. 0.14 mm);
nearly parallel-sided; slightly spatulate
not spatulate
Juxta shallow medial notch at divided at base by
base; a medial cleft;
dorsal process dorsal process
wide (ca. 0.25 mm) narrowed (ca. 0.16 mm)
at base at base
Saccus long (ca. 0.63 mm); short (ca. 0.40 mm);
as long as or longer than shorter than width
width at base of valva at base of valva
- Previously unreported characters
1,2 True only of Bruce spanworms in B.C.
3 Genitalic characters are illustrated in Eidt et al. (1966).
RESULTS
A total of 3,200 winter moths, 1,306 spanworms and 13 moths with characters interme-
date between the two species were trapped during the 13-week period. Most (2,928) of
the winter moths were recovered from the four blueberry fields in Richmond (Fig. 1: 1-4;
Spearman rank correlation coefficient = 0.8294, p < 0.001, n = 16). A total of 198 winter
moths were captured in Delta and Surrey (Fig. 1: 5 and 6), and 74 came to the ten traps
north and east of Surrey (Fig. 1: 7-16). More winter moths were trapped in the three rasp-
berry fields (Fig. 1: 11-13; X+S.D. = 10.0 + 11.27 per trap) than in three nearby blue-
berry ficlds (Fis... 1: 9,14 and 15; X +S.D. =3.33 + 4.04 per trap; t = 2.95, p = 0.042).
No winter moths were recovered from the trap in Mission (Fig. 1: 16).
Spanworms were recovered from all sites, but there was no correlation between trap
location and number of spanworms caught (Spearman rank correlation coefficient =
-0.0106, p > 0.05, n = 16). More spanworms were found in the three raspberry fields (Fig.
1: 11-13; X+S.D.= 90.33 + 101.5 per trap) than in three nearby blueberry fields (Fig. 1:
9,14and 15; X+S.D.=42 + 45.18 per trap; t = 6.912, p = 0.0023).
Eleven of the 13 moths with characters intermediate between the two species were
trapped in Richmond (Fig. 1: 1-4); two were trapped in Surrey (Fig. 1: 5).
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
42
Langley 1
Figure 1. The lower Fraser Valley of British Columbia showing the location of pheromone traps for the European winter moth
Bruce spanworm, O. bruceata (Hulst). Traps in blueberry fields are represented by circles, those in raspberry fields by squares
dous woodland by a diamond. Traps 13, 14 and 15 lie within the municipality of Matsqui. Total numbers of winter moths (first column
(second column, hatched bars) and moths with characters intermediate between the two species (third column) are indicated near each trap site.
O
8
2
9
267
fe)
Operophtera brumata (L.), and
the one in coniferous/deci-
solid bars), spanworms
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 43
Table 2
Numbers (#) and cumulative percentages (%) of Bruce spanworm, Operophtera bruceata (Hulst),
males collected from four pheromone traps in Richmond and 12 traps east of Richmond
during November, 1990, to January, 1991.
Richmond (4 traps) East of Richmond (12 traps)
Date # % # %
Nov. 6 0 0 13 2
Nov. 13 3 5 151 15.0
Nov. 20 ps 25 [35 Did
Nov. 28 I5 oF 328 5720
Bec.3 a7, 47.1 Zo 7198
Dec. 11 46 69.4 162 94.5
Dec. 13 D2 94.7 25) 99.6
Jan. 23 11 100 5 100
Most winter moths were trapped earlier in the fall than most spanworms (Fig. 2). By the
fourth week of November, 86% of the total number of winter moths had been recovered
from the traps, whereas. only 50% of the spanworm males had been caught. The
mothswith intermediate characters were trapped during the first, second and third weeks
of November, and the second week of December.
In Richmond, very few spanworms (< 10% of the total number caught) were trapped
until the first week of December but, further east, most (57%) had come to the traps by
the last week of November (Table 2).
DISCUSSION
The European winter moth is well established on blueberries in Richmond, and is present
in blueberry and raspberry plantings as far east as Matsqui (Fig. 1). Wefound winter
moths at one coniferous/deciduous site east of Richmond and suspect that they may be
established at other wooded sites in the Valley. We recommend that growers east of
Richmond, especially those in Delta and Surrey, monitor their plants closely in late
March and early April when winter moth eggs hatch.
The Bruce spanworm is also present throughout the lower Fraser Valley (Fig. 1), but
there is no correlation between location and number of spanworms trapped. Although
spanworms were numerous in Maple Ridge and Langley (Fig. 1: 8, 11), there is no histo-
ry of economic damage to fruit crops in these areas.
Both species were more numerous on raspberries than on nearby blueberries, suggest-
ing that they may prefer, or have a higher fitness on, raspberries. A more extensive survey
and developmental studies are needed to test this hypothesis.
Spanworm adults generally emerge later in the fall than winter moths (Hale, 1989), so
the pheromone trap counts (Fig. 2) probably reflect the flight periods of the two species
except, perhaps, in Richmond, where spanworms were trapped even later than at sites
further east (Table 1). We suspect that spanworm males emerging in Richmond in
November may have been attracted to calling winter moth females rather than to
pheromone traps. Several facts support this hypothesis. The pheromone (Z,Z,Z)-1,3,6,9-
nonadecatetraene has been isolated from winter moth (Roelofs ef al. 1982) and span-
worm (Underhill et a/. 1987). Spanworm males can mate successfully with winter moth
females, but pairings between winter moth males and spanworm females rarely succeed
(Hale, 1989). We recovered several possible hybrids from traps in Richmond and Surrey,
44 J. ENTOMOL. Soc. BRiT. COLUMBIA 88, DECEMBER, 1991
1000 a
800
Q.
a]
|
_~ 600
hens
®o
Q.
Tp)
S 400
re)
=_ A
an
y,
Aw
200 AM oc
Yl VY
7. Am
y} Yaa
ARM
AMmWwm He
YAMA mYwY
4a 78 Ze Cees
AWHe wo GZ
» _ MMMM wm (ZI
12 3 4 5 6 7 8 Q9 10 11 12 13
| November | December | January
Week
Figure 2. Total numbers of the European winter moth, Operophtera brumata (L.), (solid bars) and
the Bruce spanworm, O. bruceata (Hulst), (hatched bars) caught in pheromone traps in the lower
Fraser Valley during the fall and winter of 1990-91. The spanworms recovered from traps during
week 12 were probably attracted during the preceding four weeks, when traps were not emptied.
suggesting that interspecific mating may be occurring in the field. An alternative explana-
tion for the delayed spanworm catch in Richmond is that hybridization problems (Hale,
1989) may have resulted in natural selection for late-emerging spanworm.
Our results show that monitoring with pheromone traps can be used to indicate the
presence of adult winter moths, and to identify regions where the risk of winter moth
damage to crops is high. A pheromone-trap survey of the Okanagan Valley would provide
an early warning system for this pest in that area.
ACKNOWLEDGEMENTS
We thank E. Underhill and M. Giblin, of the Plant Biotechnology Institute in
Saskatoon, for providing the pheromone lures and Hara traps. We are grateful to B.
Frazer, H. R. MacCarthy, B. Vernon and two anonymous reviewers for helpful criticism
of the manuscript.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 45
REFERENCES
Brown, C.E. 1962. The life history and dispersal of the Bruce spanworm, Operophtera bruceata (Hulst),
(Lepidoptera: Geometridae). Can. Entomol. 94:1103-1107.
Cuming, F.G. 1961. The distribution, life history, and economic importance of the winter moth, Operophtera
brumata (L.) (Lepidoptera: Geometridae) in Nova Scotia. Can. Entomol. 93:135-142.
Edland, T. 1971. Wind dispersal of the winter moth larvae, Operophtera brumata L. (Lep., Geometridae) and its
relevance to control measures. Norsk. ent. Tidsskr. 18:103-107.
Eidt, D.C., Embree, D.G., and C.C. Smith. 1966. Distinguishing adults of the winter moth Operophtera bruma-
ta (L.), and Bruce spanworm O. bruceata (Hulst) (Lepidoptera: Geometridae). Can. Entomol. 98:258-261.
Ferguson, D.C. 1978. Pests not known to occur in the United States or of limited distribution. U.S.D.A. Coop.
Plant Pest Report 3:687-694.
Gillespie, D.R., Finlayson, T., Tonks, N.V., and D.A. Ross. 1978. Occurrence of the winter moth, Operophtera
brumata (Lepidoptera: Geometridae), on southern Vancouver Island, British Columbia. Can. Entomol.
110:223-224.
Hale, M.A. 1989. Factors affecting the distribution and survival of an endemic and introduced species of
Operophtera (Lepidoptera: Geometridae). M.Sc. Thesis, University of Victoria, Victoria, British Columbia,
Canada.
Pivnick, K.A. 1988. Wing colouration difference between the Bruce spanworm Operophtera bruceata (Hulst)
(Lepidoptera: Geometridae) and the winter moth Operophtera brumata (L.) on Vancouver Island. Can.
Entomol. 120:697-698.
Roelofs, W.L., Hill, A.S., Linn, C.E., Meinwald, J., Jain, S.C., Herbert, H.J., Smith, R.F. 1982. Sex pheromone
of the winter moth, a geometrid with unusually low temperature precopulatory responses. Science 217:657-
659.
Sheppard, D.H., Myers, J.H., Fitzpatrick, S., and H. Gerber. 1990. Efficacy of deltamethrin and Bacillus
thuringiensis Berliner ssp. kurstaki on larvae of winter moth, Operophtera brumata (L.) (Lepidoptera:
Geometridae) attacking blueberry in the Lower Mainland of British Columbia. J. Entomol. Soc. British
Columbia 87:25-29.
Underhill, E.W., Millar, J.G., Ring, R.A., Wong, J.W., Barton, D., and M. Giblin. 1987. Use of a sex attractant
and an inhibitor for monitoring winter moth and Bruce spanworm populations. J. Chem. Ecol. 13:1319-
1330.
Whaley, W.C. 1989. General manager's report in Thirty-sixth Annual Report of the British Columbia Blueberry
Co-Op Assoc. British Columbia Blueberry Co-Op Assoc., 31852 Marshall Rd., Abbotsford, British
Columbia. V2S 4N5.
Wolff, N.L. 1964. The Lepidoptera of Greenland. Medd. Grgnland 159: 1-74.
Cuticular metal hardening of mouthparts and claws
of some forest insects of British Columbia.
A. R. FONTAINE, N. OLSEN, R. A. RING and C. L. SINGLA
DEPARTMENT OF BIOLOGY, UNIVERSITY OF VICTORIA
VICTORIA, B.C., V8W 2Y2
ABSTRACT
The presence of metals in mouthparts and claws of some forest insects associated with
British Columbia conifers, particularly cone and seed pests, were detected and mapped by
energy dispersive X-ray microanalysis. Zinc was concentrated in the mandibular cutting
edges and claw tips of larval lepidopterans (but not in adult mouthparts), in the mandibles
and claws of larval and adult coleopterans and in the mandibles of the hymenopteran,
Megastigmus spermatotrophus. Calcium was the predominant metal in the mouth hooks of
dipteran larvae, but minor peaks of zinc or manganese were present additionally in two
species. Manganese occurred in the stylets of the hemipteran, Leprfoglossus occidentalis, in
the mandibles and claws of one coleopteran species, and with zinc in the mandibles of a
clerid predator. The function of metal concentrations in specific areas of these structures is
probably related to hardening of cuticular regions in some instances and to some other
biomechanical aspect of cuticular strengthening in other cases.
46 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
INTRODUCTION
Forest insect pests, especially those that feed on developing cones and seeds or damage
potential seed-bearing branches, have a major economic impact on coniferous forest pro-
ductivity and regeneration in British Columbia (Ruth, 1980; Wood and Van Sickle,
1987). It is of interest to forest entomologists, therefore, to know that mouthparts and
claws of some of these herbivorous pests appear to be hardened by cuticular metal
deposits that may affect abrasive wear or confer strength biomechanically. We have sur-
veyed some B.C. forest insects, emphasizing seed and cone pests, for evidence of cuticu-
lar metal hardening using energy dispersive X-ray microanalysis (ED Xa) to detect metals,
and X-ray mapping to show their morphological distribution. The information presented
here has implications in the ecology of forest insect pests and is a base for studies on the
interrelationship between hardening of insect mouthparts, particularly during develop-
ment, and insect feeding strategies.
Use of metals, such as iron, zinc, copper, manganese or silicon, to harden mouthparts
and other structures as an adaptation against excessive wear is widespread among both
aquatic and terrestrial invertebrates (Simkiss and Wilbur, 1989). This adaptation also
occurs in insects, though its extent is not particularly well known. Concentration of zinc
in the mandibles of two locust species, the original accounts of cuticular metal hardening
in insects, was related to resistance to wear in relation to feeding on tough plant material
(Hillerton and Vincent, 1982; Hillerton, Reynolds and Vincent, 1982). Hillerton and
Vincent (1982) also used EDXa and X-ray mapping to demonstrate the specific location
of zinc or manganese along the cutting edge of chewing structures in 36 herbivorous
species from 5 orders; five omnivores from 2 orders did not have metals in their mouth-
parts. Subsequently Hillerton, Robertson and Vincent (1984) demonstrated zinc or man-
ganese in the mandibles of 54 (out of 57) species of stored-product beetles, thus empha-
sizing the major role of these metals in increasing the hardness of chewing structures.
Co-occurrence of metals, i.e., two metals occurring in the same structure, has been report-
ed in some species, but its significance is not well understood. For example, ion micro-
probe techniques have demonstrated concentrations of both zinc (about 4%) and man-
ganese (about 0.4%) in the mandibular teeth of ants (Lefevre et al., 1987; Schofield et al.,
1988).
Calcium, the only other metal commonly found in insect cuticle, is prominent in
Diptera, notably in muscid flies where its presence has been related functionally to stabi-
lization of the puparial cuticle as an alternative to sclerotization, not as a hardening mech-
anism to resist abrasion (Grodowitz and Broce, 1983; Roseland et al, 1985).
MATERIALS AND METHODS
Specimens of insect larvae and adults (Table 1) were obtained from culture stocks and
collections of the Pacific Forestry Centre, Victoria, B.C., through the assistance of Mr. D.
S. Ruth. Usually they were received preserved in 70% ethanol after previous fixation, but
some live specimens were fixed by us in 2.5% glutaraldehyde in phosphate buffer, pH
7.4.
The appropriate mouthparts (mandibles, stylets, or mouth hooks) and claws were
removed, dehydrated in a graded ethanol series and air dried; alternatively they were
removed after dehydration and critical point drying. Dried structures were mounted on
carbon boats using carbon paste, then lightly sputter coated with gold. Although artifactu-
al gold peaks were thus introduced, gold-coating reduced the extreme charging problems
encountered in carbon-mounted specimens. EDXa was performed with a Tracor Northern
5500 EDXa system mounted on a JEOL 1200EX scanning transmission electron micro-
scope operated in the scanning electron microscope (SEM) mode. X-ray spectra were typ-
ically acquired from specimens tilted to 30° for 100 seconds over the energy range 0-20
keV, at an accelerating voltage of 40 kV, beam current 15 mA. Digital video images of
the specimens and corresponding X-ray maps, with appropriate controls, were acquired
and processed using Tracor Northern software. Some SEM morphology was carried out
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
Species
LEPIDOPTERA
Barbara colfaxiana
(Kearfott)
Cydia strobilella (L.)
Dioryctria abietivorella
(Grote)
Dioryctria reniculelloides
Muutura and Munroe
Holocera immaculella
McDermott
DIPTERA
Contarinia oregonensis
Foote
Delia anthracina
(Czerny)
Earomyia abietum
McAlpine
Earomyia barbara
McAlpine
HEMIPTERA
Leptoglossus occidentalis
Heidemann
HYMENOPTERA
Megastigmus
spermatotrophus
Wachtl
COLEOPTERA
Dendroctonus ponderosae
Hopkins
Enoclerus schaefferi
Barr
Neacanthocinus obliquus
Le Conte
Table 1
Taxonomic list of the forest insects surveyed, including stage of development and collection data.
Common name
Douglas fir cone moth
Spruce seed moth
Fir coneworm
Spruce coneworm
Douglas fir fall
coneworm
Douglas fir cone
gall midge
Spiral spruce cone
maggot
Fir cone maggot
Fir cone maggot
Seed bug
Douglas fir seed chalcid
Mountain pine beetle
Checkered beetle,
predator upon B.
colfaxiana
Long-horned
wood borer
stage of life cycle
eggs
instars 1-4
adult females
instar |
instar 4
larva
larva
larva
larva
instars 1-4
eggs
larva
larva
instars |, 2
adult
larva
instars 3, 4;
adults
larva
adult
47
Collection data
Keremeos B.C.
18/5/87
cone collection 28/6/84
Tappen, B.C. 26/5/87
White spruce cones,
Smithers, B.C. 6/8/68
Mesachie Lake, B.C.
18/8/80
Oliver, B.C. 26/5/87
Hedley, B.C. 2/6/87
Mesachie Lake, B.C.
15/8/86
White spruce cones,
Prince George, B.C.
11/6/87
Tappen, B.C. 26/5/87
Grand fir cones,
Ladysmith, B.C.
6/8/68
Douglas fir cones,
Ladysmith, B.C. 28/8/72
lab rearings 22/5/87
lab rearings 8/5/87
Douglas fir cone seed,
Courtney, B.C. 19/9/71
from Lodgepole pine
held in cold storage.
15/7/87
cone collection,
Keremeos, B.C. 14/5/87
lab rearings 15/7/87
48 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
Table 2
Metals in the feeding structures and claws of forest insects demonstrated by EDXa.
Species Stage Structure Metals
LEPIDOPTERA
Barbara colfaxiana eggs none
instars 1-4 mandibles Zn
claws Zn
adult mouthparts none
Cydia strobilella instar | mandibles Zn
claws Zn
instar 2 mandibles Zn
claws Zn
Dioryctria abietivorella larva mandibles Zn
claws Zn
Dioryctria reniculelloides larva mandibles Zn
claws Zn
Holocera immaculella larva mandibles Zn
claws Zn
DIPTERA
Contarinia oregonensis larva spatula none
Delia anthracina eggs none
instar 2 mouth hooks Ca, Mn
instar 3 cuticle none
mouth hooks Ca, Mn
instar 4 mouth hooks Ca, Mn
Earomyia abietum larva mouth hooks Ca
Earomyia barbara larva cuticle Ca
mouth hooks Ca, Zn
HEMIPTERA
Leptoglossus occidentalis instar | proboscis none
claws none
instar 2 proboscis Mn
claws none
adult proboscis Mn
claws none
HYMENOPTERA
Megastigmus spermatotrophus larva mandibles Zn
COLEOPTERA
Dendroctonus ponderosae instar 3 mandibles Zn
instar 4 mandibles Zn
adult mandibles Zn
claws Zn
Enoclerus schaefferi larva mandibles Zn, Mn.
claws TA
anal hooks Zn, Mn
Neacanthocinus obliquus adult mandibles Mn
claws Mn
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 49
A Acquisition time, 100 secs X-ray counts 1024
768
0.000 KeV 20.480
Acquisition time, 100 secs X-ray counts 2048
1536
0.000 KeV 20.480
Cc Acquisition time, 100 secs X-ray counts 1024
768
0.000 KeV 20.480
Fig. 1. Representative EDXa spectra. Gold peaks are artifacts as explained in the text. A. From the
mandibular cutting edge of B. colfaxiana, instar 4, showing prominence of zinc peaks. A chlorine
peak is also evident. B. From a claw tip of B. colfaxiana, instar 4, showing the presence of zinc. C.
From a stylet of an L. occidentalis adult, showing a relatively weak manganese peak.
on conventionally prepared specimens using a JEOL JSM-35 scanning electron micro-
scope.
RESULTS
A synopsis of metals detected is shown in Table 2. Each report of a metal finding is based
on analysis of at least 3 specimens. Spectra were typically replicated three times for each
sample point.
Among lepidopteran species, larvae showed a consistent pattern of zinc accumulations
along the cutting edge of the mandibles and in claw tips. Zinc or other metals were not
detectable in the cuticle of the body generally except in these areas. Most information on
zinc distribution in the lepidopterans available to us is from B. colfaxiana for which we
had a full range of stages. In that species, zinc is found along the cutting edge of the
mandibles in all instars (Figs. 1A, 3) but it is not present in the mouth structures of the
adult. We did not attempt accurate quantification but, estimated from X-ray counts for the
Zn Ka peaks and comparison of X-ray images, the relative amount of zinc along the
mandibular cutting edge apparently increases in each successive instar. Zinc is also pre-
cisely localized in the larval claw tips (Figs. 1B, 4). Again each instar shows relatively
50. J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
Acquisition time, 100 secs X-ray counts 512
384
0.000 KeV 20.480
Acquisition time, 100 secs X-ray counts 2048
1536
0.000 KeV 20.480
Fig. 2. Representative EDXa spectra from dipteran mouth hooks.. Gold peaks are artefacts as
explained in the text. A. From the base of a mouth hook of Earomyia barbara showing the co-
occurrence of calcium and zinc. B. From the tip of a mouth hook of Delia anthracina showing the
co-occurrence of calcium and manganese.
greater zinc concentrations, but it is absent from adult claw tips. A chlorine peak accom-
panies the zinc peak in the mandibles, but chlorine is distributed more widely throughout
the mandibular cuticle. Chlorine appears to be in highest concentrations along mandibular
cutting edges where zinc is localized. Minor chlorine peaks are inconsistently present in
claws, but not generally over the body surface. A potassium peak is common over the
entire body surface. Gold peaks are, of course, artifacts of gold-coating.
Although the material available for analysis was not so extensive, the larvae of four
other lepidopteran species showed a similar pattern of zinc distribution, accompanied by
chlorine as described above. Zinc X-ray images show the spatial distribution of zinc in the
mandibles and claw tips of the Douglas fir fall cone worm, H. immaculella, for example
(Fig. 5, 6), and demonstrate the consistency of the pattern of metal distribution in these
lepidopteran species.
Zinc was found in the small mandibles of the larvae of the hymenopteran, M. sperma-
totrophus, but X-ray maps were not successfully obtained because their small size proved
difficult to work with. The larvae lack claws.
The coleopteran species did not show a consistent pattern of metal accumulation. The
mountain pine beetle, D. ponderosae, had major accumulations of zinc in the cutting
edges of the mandible of larvae and adults. Small amounts of manganese accompanied
zinc in the mandibles of the larval checkered beetle, E. schaefferi, and zinc alone occurred
in the larval claw tips. The long-horned wood borer, N. obliquus, had small accumula-
tions of manganese in adult mandibles and claw tips.
The seed bug, L. occidentalis, had small amounts of manganese (Fig. 1C) in stylets of
the second instar nymph and adult, but none was detected in the first instar nor in the
claws of any of the stages examined. Where manganese occurred, it was not restricted to
the tip but was distributed uniformly throughout the stylet.
Dipteran species had complex patterns of metal accumulations, but calcium was typi-
cally prominent. Calcium was found widely distributed throughout the cuticle of mouth
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 51
3 35 MICRONS._W eS ees 35 MICRONS...
Fig. 3. SEM and zinc X-ray images of the mandible of Barbara colfaxiana, instar 3. Right, digi-
tized SEM image of the left mandible, inner surface. Left, zinc X-ray image‘indicating the morpho-
logical distribution of zinc within that mandible
A 6.94 MICRONS =” 6.94 MICRONS
Fig. 4. SEM and zinc X-ray images of a claw of Barbara colfaxiana, instar 3. Right, digitized SEM
image. Left, zinc X-ray image showing the distribution of zinc in the claw tip.
hooks of all species, with the exception of C. oregonensis. Additionally, zinc was detect-
ed together with calcium in the mouth hooks of E. barbara (Fig 2A) and manganese along
with calcium in D. anthracina (Fig. 2B). Low levels of calcium were also present
throughout much of the larval cuticle of E. barbara.
52 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
Fig. 5. SEM and zinc X-ray images of the mandible of a larval Holocera immaculella. Right, SEM
image, left mandible, inner face. Left, zinc X-ray image showing the distribution of zinc in that
mandible.
Fig. 6. SEM and zinc X-ray images of a claw of a larval Holocera immaculella. Right, SEM image
of a claw. Left, zinc X-ray image showing the distribution of zinc in the claw tip.
DISCUSSION
In discussing cuticular metal hardening in arthropods, we are considering non-crystalline,
amorphous metal deposits within cuticular substance (Hillerton and Vincent, 1982;
Schofield and Lefevre, 1989), a situation distinct from better known hardening mecha-
nisms based on highly ordered biominerals, as in ferric mineral capping of chiton or fish
teeth (Sparks et al., 1990).
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 53
Cuticular metal hardening in insects appears to have at least two aspects, probably
related to differing biomechanical mechanisms. In one case, much metal is deposited in
association with a well-defined area subject to wear; for example, zinc deposits along the
cutting edge of coleopteran mandibles. In the other situation, relatively little metal is dis-
tributed uniformly throughout a structure; for example, manganese in the proboscis of the
seed bug where there is too little metal to believe that its mere physical presence confers
hardness. However, in a situation like this, a little metal could significantly affect stiffness
or some other biomechanical property via promotion of secondary bonding of cuticular
proteins (Hillerton and Vincent, 1982; Schofield and Lefevre, 1989). In our view, which
of these alternative metal-based adaptations is employed appears to be related to the feed-
ing biology of the insect. In some species, two metals co-occur in a structure, suggesting
to us cases where the function and biomechanics of the structure require simultaneous
employment of both adaptations.
Our evidence shows that zinc concentrations along mandibular cutting edges and in
claw tips are common in herbivorous forest insects, particularly where feeding requires
mining through bark or cone scales or prolonged tunneling within inner bark or develop-
ing cones (Ruth, 1980; Wood and Van Sickle, 1987). The lepidopteran species examined
share a similar feeding strategy, mining as larvae into cones to feed on developing seeds.
Zinc is prominent in mandibles and claws of adult and larval mountain pine beetles, D.
ponderosae, which tunnel through bark as adults and as larvae mine tissues of inner bark.
Zinc 1s found in the mandibles and claws of the checkered beetle, E. schaefferi, which,
although a predator upon B. colfaxiana larvae, mines through bark or cones to find them
(Moeck and Safranyik, 1984). The Douglas fir seed wasp, M. spermatotrophus, oviposits
through cone scales into developing seeds on which its larvae feed (Ruth, 1980; Wood
and Van Sickle, 1987) using zinc-hardened mandibles.
Development of toughness in plants is a defensive adaptation known to affect mor-
phology, feeding behaviour and distribution patterns of some herbivorous insects (Feeny,
1970; Djamin and Pathak, 1979; Raupp, 1985). Such relationships are likely to exist in
the mouthpart and claw tip adaptations of herbivorous forest insects, particularly cone and
seed insects.
Zinc is the metal typically accumulated by terrestrial arthropods for cuticular harden-
ing of the kind described above. For example, zinc occurs in the cheliceral fangs of sever-
al spiders (Schofield and Lefevre, 1989), in the tips of chelicerae and pedipalps of a scor-
pion and in the mouthparts of a mite (Fontaine and Pedersen, unpublished observations).
Metals accumulated by aquatic organisms for cuticular hardening are more diverse. Some
examples include zinc or copper in marine polychaete jaws (Gibbs and Bryan, 1980), sili-
con in chaetognath teeth (Bone ef al. 1983), and silicon and zinc in copepod mandibles
(Perry et al., 1983).
The alternative pattern for metal deposition is that the metal occurs in small quantities
distributed diffusely within a structure. As suggested above, metals in these situations
may have biomechanical roles (e.g., stiffness, resistance to fracture) via metal biochem-
istry but their function is unlikely to be metal hardening as such. Manganese has this sort
of distribution in the species we surveyed. In contrast to the herbivorous insects, the man-
ganese-accumulating species do not mine or chew continually and employ diverse feed-
ing strategies as in, for example, the seed bug, L. occidentalis, and the long-horned wood
borer, N. obliquus. In the seed bug, manganese occurred in the stylets of the second instar
and adult which feed on cone seeds by inserting the stylet through the tough seed coat,
enzymatically digesting and then ingesting the endosperm (Ruth, 1980). The first instar
nymph feeds on foliage rather than on seeds and lacked any metal in the stylets. In con-
trast to the herbivorous chewing insects, mouthparts like these must have different biome-
chanical requirements which, in our opinion, are reflected in the metal distribution pat-
tern.
Major amounts of calcium deposits in insect cuticle seem to be restricted to dipteran
species, according to our results and others (Grodowitz and Broce, 1983; Roseland et al,
1985). Calcium may be functionally analogous to manganese since it also occurs in small
54 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
quantities with a diffuse distribution. However, it is interesting to note that calcium co-
occurs with manganese in D. anthracina mouth hooks and with zinc in E. barbara mouth
hooks.
Co-occurring metals (calcium/manganese in D. anthracina; calcium/zinc in Earomyia
barbara; manganese/zinc in Enoclerus schaefferi) suggest structures where interaction of
two distinct biomechanical mechanisms is required and is accomplished by using differ-
ent metal hardening processes (Schofield et al., 1988; Schofield and Lefevre, 1989).
Once again, these differences may reflect adaptive requirements based on feeding or
dietary differences, such as relative abrasiveness of food. Among the fir cone maggots,
for example, Earomyia barbara (calcium/zinc) uses its mouth hooks to feed on Douglas
fir cones which are tougher than the balsam fir cones fed on by E. abietum (calcium
alone) (D. S. Ruth, personal communication).
Hillerton, Robertson and Vincent (1984) considered the occurrence of zinc or man-
ganese in mandibles of coleopteran species to be correlated with taxonomy and to be a
reflection of evolutionary history of the group, despite some paradoxes of metal distribu-
tion within some sub-taxa. In our view, the metal or metals that occur in a species are
more likely to be correlated with biomechanical adaptations of feeding structures. Since
species groups within a family often employ a similar feeding strategy, they are likely to
share similar biomechanical adaptations and similar uses for a metal. By contrast, calcium
accumulation is apparently unique to Diptera and in that taxon may well be the result of
phylogenetic conservatism.
ACKNOWLEDGEMENTS
We are grateful to D. S. Ruth, T. S. Sahota and R. F. Shepherd, Pacific Forestry Centre,
for providing specimens and valuable discussions and to H. F. Dietrich, University of
Victoria, for technical assistance.
REFERENCES
Bone, Q., K. P. Ryan and A. L. Pulsford. 1983. The structure and composition of the teeth and grasping spines
of chaetognaths. J. mar. biol. Ass. U.K. 63:929-939.
Djamin, A., and M. D. Pathak. 1979. Role of silica in resistance to Asiatic rice borer, Chilo suppressalis
(Walker), in rice varieties. J. Econ. Entomol. 60:347-351.
Feeny, P. 1970. Seasonal changes in oak leaf tannins and nutrients as a cause of spring feeding by winter moth
caterpillars. Ecology 51:565-581.
Gibbs, P. E., and G. W. Bryan. 1980. Copper - the major metal component of glycerid polychaete jaws. J. mar.
biol. Ass. U.K. 60:205-214. :
Grodowitz, M. J., and A. B. Broce. 1983. Calcium storage in face fly (Diptera: Muscidae) larvae for puparium
formation. Ann. Entomol. Soc. Am. 76:418-424.
Hillerton, J. E , and J. F. V. Vincent. 1982. The specific location of zinc in insect mandibles. J. exp. Biol.
101:333-336.
Hillerton, J. E., B. Robertson, and J. V. F. Vincent. 1984. The presence of zinc or manganese as the predominant
metal in the mandibles of adult, stored-product beetles. J. Stored Prod. Res. 20:133-137.
Hillerton, J. E., S. E. Reynolds and J. V. F. Vincent. 1982. On the indentation hardness of insect cuticle. J. exp.
Biol. 96:45-52.
Lefevre, H. W., R. M. S. Schofield, J. C. Overley, and J. D. MacDonald. 1987. Scanning transmission ion
microscopy as it complements particle induced X-ray emission microanalysis. Scanning Micr. 1:879-889.
Moeck, H. A., and L. Safranyik. 1984. Assessment of predator and parasitoid control of bark beetles.
Environment Canada. Canadian Forestry Service, Pacific Forest Research Centre, Victoria, B. C.
Information Report BC-X-248.
Perry, C. C., G. W. Grime and F. Watt. 1988. An X-ray analytical study of mandibles trom Calanus pacificus.
Nucl. instr. Meth. B30:367-371.
Raupp, M. J. 1985. Effects of leaf toughness on mandibular wear of the leaf beetle, Plagioderma versicolora.
Ecological Entomology 10:73-79.
Roseland, C. R., M. J. Grodowitz, K. J. Kramer, T. L. Hopkins, and A. B. Broce, 1985. Stabilization of mineral-
ized and sclerotized puparial cuticle of Muscid flies. Insect Biochem. 15:521-528.
Ruth, D. S. 1980. A guide to insect pests in Douglas-fir seed orchards. Environment Canada, Canadian Forestry
Service, Pacific Forest Research Centre, Victoria, B. C. Information Report BC-X-204.
Schofield, R. M. S., H. W. Lefevre, J. C., Overley and J. D. MacDonald. 1988. X-ray microanalytical surveys of
minor element concentration in unsectioned biological samples. Nucl. instr. Meth., B30:398-403.
J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991 0
Schofield, R., and H. Lefevre, 1989. High concentrations of zinc in the fangs and manganese in the teeth of spi-
ders. J. exp. Biol. 144:577-581.
Simkiss, K., and K. M. Wilbur. 1989. Biomineralization: Cell Biology and Mineral Deposition. Academic Press,
San Diego.
Sparks, N. H. C., P. J. Motta, R. P. Shellis, V. J. Wade and S. Mann. 1990. An analytical electron microscopy
study of iron-rich teeth from the butterflyfish (Chaetodon ornatissimus). J. exp. Biol. 151:371-385.
Wood, C. S., and A. Van Sickle. 1987. Forest insect and disease conditions, British Columbia and Yukon, 1986.
Environment Canada, Canadian Forestry Service, Pacific Forest Research Centre, Victoria, B. C.
Information Report BC-X-287.
56 J. ENTOMOL. Soc. BRIT. COLUMBIA 88, DECEMBER, 1991
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Volume 88 Issued December 1991 ISSN #007 1-0733
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Taylor, S., Alfaro, R.I. and Lewis, Kornelia. Factors affecting the incidence
of white pine weevil damage to white spruce in the Prince George Region
of British Columbia
Forbes, A.R. and C.K Chan. The Aphids (Homoptera: Aphididae)
of British Columbia 20. Further additions
Mayer, D.F. and J.D. Lunden. Honey bee foraging on dandelion and
apple in apple orchards
Safranyik, L. and D.A. Linton. Unseasonably low fall and winter temperatures
affecting mountain pine beetle and pine engraver beetle populations and
damage in the British Columbia Chilcotin Region
Toba, H.H. and J.F. Howell. An improved system for mass-rearing
codling moths
MacCarthy, H.R. Compound eye of male Stylops pacifica
(Strepsiptera; Stylopidae)
Morewood, W.D. Larvae of Hyalophora euryalus kasloensis
(Lepidoptera: Saturniidae)
Miller, Daniel R. and Jean P. Lafontaine. cis-Verbenol: An aggregation
pheromone for the mountain pine beetle, Dendroctonus ponderosae
Hopkins (Coleoptera: Scolytidae)
Fitzpatrick, Sheila M. and James T. Troubridge. Melanchra picta (Harris)
(Lepidoptera: Noctuidae), a cutworm new to British Columbia
Fitzpatrick, Sheila M., James T. Troubridge and Barbara Peterson. Distribution of
European winter moth, Operophtera brumata (L.), and Bruce spanworm,
O. bruceata (Hulst), in the lower Fraser Valley, British Columbia
Fontaine, A.R., N. Olsen, R.A. Ring and C. L. Singla. Cuticular metal hardening
of mouthparts and claws of some forest insects of British Columbia
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COVER: An adult female Dytiscus dauricus Gebler (Dytiscidae: Coleoptera) drawn with
pen and ink by David Young from specimens collected by Adrian de Bruyn. The specimen is
33 mm long. The species is Holarctic in distribution and can be collected along the margins
of ponds, slow brown water streams and bush- or tree-ringed permanent ponds and lakes in
British Columbia.
Designed, typeset and printed by
Printing & Duplicating Services
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J. ENTOMOL. Soc. Brit. CoLuMBIA 89, DECEMBER, 1992
Journal
of the
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of British Columbia
Volume 89 Issued December 1992 ISSN #0071-0733
Directors of the Entomological Society of British Columbia, 1992-93 ....................
Blacker, N.C. Some ants (Hymenoptera: Formicidae) from
Southern Vancouver Island, British Columbia ......+.......000 0c cee e sees taseees
Lindgren, B. Staffan. Attraction of Douglas-fir beetle, spruce beetle and a
bark beetle predator (Coleoptera: Scolytidae and Cleridae) to
CHAMMOMeksS OF LLOMANM, 25 e042 acee ce 4 in Powe oot SH wo Gee saw e enous ea aes
Cossentine, J.E. and L.B. Jensen. Establishment of Phyllonorycter mespilella
(Hiibner) (Lepidoptera:Gracillariidae) and its parasitoid, Pnigalio flavipes
(Hymenoptera:Eulophidae), in fruit orchards in the Okanagan and
Similkamecen Valleys of British Columbia ..... 0403 240i. 0hoaste ws saekae see eases
Toba, H.H. and J.D. Campbell. Wireworm (Coleoptera: Elateridae) survey in
wheat-growing areas of northcentral and northeastern Oregon ..............0.200005.
Baird, Craig R., Keith W. Dorschner, and Carolyn J. Nyberg. Biology of the black
vine weevil Otiorhynchus sulcatus on hop in Idaho (Coleoptera: Curculionidae) .........
Scudder, G.G.E. The distribution and life cycle of Reduvius personatus (L.)
(Hemiptera: Reduviidae) in Canada. .\....05.06.0 60.526 a cba e ee eee oe ee ee ese ests eee 2
McIntosh, R.L. and J.A. McLean. A life stage development index for Trypodendron
lineatum (Oliv.) in a spruce boom on the Alberni Canal, Vancouver Island .............
Lam, Desmond K.W., and John A. McLean. Seasonal abundance and distribution of
ambrosia beetles on the North Arm of the Fraser River, British Columbia ..............
W.R. Jacobi. Potential insect vectors of the black stain root disease pathogen
Ol SOulMernly dUCOUVERISIANG..4), succes alo. ba cee Oe oo esas eee dass ore
Suomi, Daniel A. and Roger D. Akre. Distribution of economically important,
wood-infesting anobiid beetles in the Pacific Northwest .......0..0.00.00 00.0 cece eee eee
Suomi, Daniel A. and Roger D. Akre. Characteristics of structures attacked by the
wood-infesting beetle, Hemicoelus gibbicollis (Coleoptera: Anobiidae) ................
OMe E LOH ON TRIBUPORS: 2% 2.06 0 bes bese ogc esd dedandan rave tes eames nee Sees
2)
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54
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J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
DIRECTORS OF THE ENTOMOLOGICAL SOCIETY
OF BRITISH COLUMBIA FOR 1992-93
President
Terry Shore
PFC, Victoria
President-Elect
Sheila Fitzpatrick
Agriculture Canada, Vancouver
Past-President
Bob Vernon
Agriculture Canada, Vancouver
Secretary
Sharon Clements
Agriculture Canada, Vancouver
Treasurer
Jim Troubridge
Agriculture Canada, Vancouver
Editorial Committee (Journal)
Richard Ring (Editor) H.R. MacCarthy David Raworth
Editor (Boreus)
Imre Otvos
PFC, Victoria
Directors
T. Lowery (2nd) D.Morewood (2nd)
R. Bennett (ist) A. Chow (Ist) S. Lindgren (1st)
Honorary Auditor
Chris Guppy
Regional Director of National Society
Terry Shore
PFC, Victoria
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 3
Some ants (Hymenoptera: Formicidae) from Southern
Vancouver Island, British Columbia
N.C. BLACKER
C/O BIOLOGY DEPARTMENT, UNIVERSITY OF VICTORIA,
VICTORIA, B.C., V8W 2Y2
ABSTRACT
A study of the ants collected in and around Victoria and on Thetis Island during the Autumn
of 1987 and the Spring of 1988 is described. Twenty-four species were found, and the
locations and habitats have been noted. Two of the Leptothorax species are believed to be
new records for Canada and another remains unidentified. Some myrmecophiles were also
recorded.
INTRODUCTION
Little has been published on the ant fauna of British Columbia. According to Buckell (1932),
Muesebeck (1951), and Ayre (in Sharplin, 1966), between 45 and 55 species, subspecies and
varieties have been recorded, although the taxonomic status of some is uncertain. The
Victoria region, at the southern tip of Vancouver Island, has an equable climate, and this,
combined with a considerable diversity of habitats, would be expected to make an
investigation of its ant fauna worthwhile.
The west coast of British Columbia is well known for its heavy rainfall. The highlands
west of Victoria receive about 54” (137 cm) of rain annually, but Victoria itself is in their rain
shadow and so receives only half of this amount, most of which falls during the winter. As a
result, Victoria has the lowest midsummer rainfall in Canada (Kerr, 1951), and drought often
withers the vegetation, even though temperatures are not particularly high. This is
significant as ants are influenced by soil surface temperatures rather than the overall
meteorological climate. Thus, summer sunshine is very important and mild winter weather
is largely irrelevant.
The rainfall gradient also increases habitat diversity by creating a series of vegetation
zones, the effect being amplified by variations in relief. Several ecological classifications
have been proposed (Hagmeier, 1965; Roemer, 1972; McMinn, 1976; and Pavlick, 1986).
The major vegetation types listed in order of increasing moisture are:
(A) Grass balds/Garry oak woodland. This consists of rock outcrops with grass and mosses and
scattered oaks (Quercus garryana).
(B) Douglas fir forest. Douglas fir (Pseudotsuga menziesii) often with scattered Arbutus
menziesii and an understory of mosses and, in moister sites, Oregon grape (Berberis spp.).
(C) Western red cedar forest. Dense stands of cedar (Thuja plicata) often with western swordfern
(Polystichum munitum) beneath.
(D) Coastal western hemlock forest (Tsuga heterophylla). Absent from the immediate Victoria
area.
There is also a number of types which are either of localised occurrence or are due to human
activities:
(E) Wet deciduous forests
(F) Meadows (dry and wet)
(G) Bogs
(H) Beaches, sand dunes
(1) Urban and suburban.
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
Table 1
Ants of Southern Vancouver Island
A
Locality
Species X a b c d € ie g h 1 J k l
(1) Myrmica emeryana group sp. a S
(2) M. incompleta a s s a a
(3) Stenamma diecki a S S
(4) Aphaenogaster subterranea occidentalis a S a B S s ‘ai
(5) Solenopsis molesta a
(6) Leptothorax muscorum ; S a
(7) L. muscorum group sp. “uvicensis” 8
(8) L. rugatulus a
(9) L. melanderi (?) a a
(10) L. nevadensis (?) x]
(11) Tapinoma sessile a
(12) Brachymyrmex depilis
(13) Lasius pallitarsis
(14) L. altenus
(15) Camponotus modoc
(16) C. laevigatus
(17) C. vicinus
(18) Formica subnuda S
(19) F. obscuripes a
(20) F accreta ) ie S ‘
(20a) F. sp. “fuliginothorax” a ai S wi S
(21) Ek pacificas s s |
(22) F. neorufibarbis a
(23) F. subpolita |
(24) F. lasioides @ ia a a S a
Site Totaln = 9 10 3 12 12 5 Il 9 2 7 5 2 5
a
EEEHE &
i?)
Ww a
an |
Si
72)
BH
Tp
ES
B
n
72)
w
7)
By
Locality , Habitat type (see text) Locality Habitat type (see text)
Pilkey Pt area (Thetis Is.) B g Uplands Park
A
Hel
Blenkinsop Rd and Lake Shelbourne St I
I
I
F
Specimen taken ®
F
UVic Campus A; CoE] Pembroke St
A Sight Record = s
J
Mt Tolmie k Stanley Ave area
Cedar Hill Crossroads I | Coast, Clover Pt westwards
Cadboro Pt Peninsula B, I
»oTAaaAacg>n x
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 5
MATERIALS AND METHODS
Specimens were collected by hand and preserved in 25% isopropyl alcohol containing traces
of copper sulphate. 70% ethyl alcohol can also be used. Foraging workers were mostly taken
from the soil surface and from tree trunks. Nests were located under stones and in or under
fallen logs and tree stumps. No excavations were carried out, so highly subterranean species
and those that nest only in the soil are likely to be under-represented in, or absent from, the
collection.
RESULTS AND DISCUSSION
The results are based on collections made in September/October 1987 and May 1988, and are
summarised in Table |. The collection sites mentioned are shown on Figures la and 1b. The
survey was not comprehensive —only habitats of six types were investigated —so there is
enormous scope for future work.
Twenty-four definite species were found, several on a single occasion only. The
Formicinae is the dominant subfamily with 13 species, followed by the Myrmicinae with 10
Species and a single member of the Dolichoderinae (Table 2).
A number of the identifications are tentative because the taxonomy of many groups of
North American ants is uncertain, and synonyms exist for many species. Because of this, all
Myrmica and Leptothorax species are illustrated and the latter are also briefly described.
Subfamily Myrmicinae
A large subfamily, the members are characterised by a sting and a two-segmented
petiolus. Pupae are never enclosed in cocoons. Tropical genera display a great diversity of
form, but the species listed here are all rather conservative in appearance and behaviour,
being well armoured and slow moving. Body surfaces are usually sculptured except for the
gaster. Only Myrmica (with two species) and Leptothorax (with five) were represented by
more than one species. This is a surprisingly small number in the former case. Two of the
Leptothorax, L. melanderi and L. nevadensis, are believed to be new records for Canada and
another has not been identified. Additional species could occur.
(1) Myrmica emeryana group sp. (Fig. 2a)
A typical Myrmica species, length 4-4.5 mm with foreparts reddish-brown, gaster
slightly darker. Head and thorax coarsely rugose. Antennal scapes sharply angled near base.
Widespread rather than abundant in short turf. Both this and the next species were more in
evidence in May 1988 than in the hot, dry autumn of 1987. A small alate female of about 5
mm was taken in mid-September 1987 near Uplands Park. It is assumed to be of this species
although the ventral surface of the petiole is not obviously convex.
(2) Myrmica incompleta Provancher (Fig. 2b)
Slightly larger than the previous species (about 4.5 mm) with both head and gaster
normally dark. Head and thorax with coarse sulcations. Antennal scapes evenly curved from
base. It was first taken on the beach at Oak Bay, otherwise its occurrence was similar to that
of the previous species, but with some preference for damper, more thickly vegetated sites.
Myrmica colonies typically contain 500-1500 workers.
(3) Stenamma diecki Emery
The workers of this species are small (3.5 mm), slender and dark reddish-brown. When
foraging they are slow moving and inconspicuous. Colonies contain approximately 100
workers and typically occur under stones in shaded sites. Careful searching in red cedar
forest usually reveals one or two. Alates were present in the nests in September and October
1987:
(4) Aphaenogaster subterranea occidentalis Emery
Workers of this common species may initially be mistaken for Myrmica but are more
slender and shiny —somewhat similar in shape to Stenamma, although larger. They are most
often seen above ground in the evening. Colonies are found under large stones in Garry oak
woodland, Douglas fir forest, and gardens. They are similar in size to those of Myrmicu
species (4-5 mm).
6 J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
(5) Solenopsis molesta Say
This tiny (1.5 mm) yellow, thief ant was taken only once. About 20 workers and pupae
were found under a small stone in a shaded area of Douglas fir forest on Thetis Island, a few
feet from a Lasius alienus colony. It is probably widespread, but is easily overlooked due to
its subterranean habits. Mature Solenopsis colonies can be very populous.
Table 2
Relative abundance of the ant fauna in the
vicinity of Victoria, B.C. by habitat type
Habitat Types
A B C F H I
(1) Myrmica emeryana group sp. C
(2) M. incompleta C GC
(3) Stenamma diecki 2 S
(4) Aphaenogaster subterranea occidentalis V
(Peek
(5) Solenopsis molesta
DTN <
nN
(6) Leptothorax muscorum
WN
(7) L. muscorum group sp. “uvicensis”
(8) L. rugatulus
(9) L. melanderi (?)
(10) L. nevadensis (?)
(11) Tapinoma sessile
(12) Brachymyrmex depilis
CNNnHNNA
”n
(13) Lasius pallitarsis
(14) L. alienus
(15) Camponotus modoc
(16) C. laevigatus
(17) C. vicinus S
(18) Formica subnuda ‘& C
(19) F obscuripes S
(20) F. accreta V V s Z Vv Vv
(20a) F. sp. “fuliginothorax” S S
(21) F. pacifica C
(22) F. neorufibarbis S
(23) F. subpolita | S
(24) F: lasioides V V Vv
GY A =
G
Habitat Types A—I (see text)
V = Very common or locally abundant
Fairly or locally common
€
S Scarce to very rare
?
II
Status uncertain
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 ij
(6) Leptothorax muscorum (Nylander) (Fig. 2c)
Workers of this species resemble a small (3.5 mm) short legged Myrmica, reddish-brown
with head and gaster darker. Female castes of this and the next two species have 1I-
segmented antennae. Clypeus with slight but distinct trough. Mesopropodeal suture distinct
from above. Tibiae and scapes may have some sub-erect hairs, looped on the latter. Antennal
clubs dark. Funiculus segments 2-6 only marginally longer than broad. Coarse sculpture
defining a deep, rounded well for antennal insertions. Gaster slightly convex at junction with
postpetiole. Leptothorax colonies are usually small, with 50-200 workers. Several were
found in stumps in the University Gardens. Also seen on Mt. Douglas and perhaps also on
Mt. Tolmie, but no specimens were taken at these sites.
Note — The European L. muscorum has not been recorded east of the Urals (Collingwood,
1979). If the North American species is truly identical this presents an interesting
biogeographical puzzle.
(7) Leptothorax muscorum group sp. “uvicensis” (Fig 2d)
This species is blackish in colour and less strongly sculptured than the previous species.
Clypeal trough indistinct. Mesopropodeal suture less distinct from above. Antennal well
also less sharply defined and more oval in shape. The thorax of this species is slightly flatter
and more slender in profile than the previous species, but broader in dorsal view. Dorsal
surface of petiole rises to a distinctive peak. A single colony was found nesting in a stump in
the University Gardens, very close to, but completely separate from, a L. muscorum colony.
It is possible that L.m. “uvicensis” is an extreme variant of L. muscorum, but the differences
are sufficient for it to be tentatively regarded as distinct, allied to species such as L. wilsoni
and L. crassipilis. More specimens, including alates, are needed.
(8) Leptothorax rugatulus Emery (Fig. 2e)
Despite having 11-segmented antennae L. rugatulus is quite distinct from the previous
two species and more like the following two in general appearance. Workers are 2.5-3.0 mm
long, reddish-brown, with head and gaster darker. It is solidly built, with a somewhat box-
shaped thorax. Mesopropodeal suture indistinct. Propodeal spines of moderate length and
divergent. Appendage hairs mostly sub-erect or decumbent. Antennal clubs pale. Funiculus
segments 2-6 distinctly longer than broad. Gaster concave at junction with postpetiole, in
contrast to the previous two species. This species nests under stones in dry, grassy Sites.
(9) Leptothorax melanderi Wheeler (Fig 2f)
This is a yellowish-brown species, length about 2.5 mm. Antennae 12-segmented, clubs
pale. First funiculus segment about as long as the next two. Head and thorax punctate
reticulate. Propodeal spines characteristically upright. It is tentatively identified as L.
melanderi after examination of species from Montana held in the British Museum (Natural
History) in London. The Montana species are, however, larger and have relatively shorter
propodeal spines than those described above. Similar species which could occur in the
province include L. ambiguus (which has 11-segmented antennae) and L. nitens. This is the
most widespread Leptothorax species, usually nesting under stones in mossy, semi-shaded
sites. When the nest stone is lifted the workers often remain motionless for several seconds,
then simultaneously start running about, presumably triggered by the release of an alarm
pheromone.
(10) Leptothorax nevadensis Wheeler (Fig. 2g)
This species is blackish, length about 2.5 mm. Antennae 12-segmented with dark clubs.
First funiculus segment distinctly longer than next two. Head and thorax more densely and
evenly punctate reticulate than the previous species and propodeal spines flatter. The high,
rounded petiole is distinctive. The specimen described here compares well with those in the
British Museum collection although it is again slightly smaller in size. From the material
examined it is difficult to understand why Creighton (1950) treats L. melanderi as a
subspecies of L. nevadensis. They appear to be quite distinct, particularly if due weight is
given to the morphology of the petiolus region, rather than to sculpture. A single worker was
taken in Upiands Park. It was captured in late afternoon in a very dry, stony area with very
short grass. To the author’s knowledge, no Leptothorax with 12-segmented antennae have
previously been recorded from British Columbia.
8 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
Nanalme a
(After Tourlsm British
Columbia, 1986, adapted.)
(After Westen, 1986,
adapted.)
2 miles
eee) |
Figure 1b. Location of collection sites in the Victoria region.
J. ENTomMoL-. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 9
Subfamily Dolichoderinae
Members of this subfamily are mostly monotonous in appearance. They are lightly
amoured and have only a single petiole segment. The sting is vestigial or absent but the
poison glands produce effective repellents. Pupae are naked. A single species was found.
(11) Tapinoma sessile Say
The workers of this species are small (2.5 mm), blackish and very agile. It is adaptable
and can occur in a variety of habitats. It was taken at several scattered sites, a few hundred
workers at most.
Subfamily Formicinae
Ants of this subfamily are similar to the Dolichoderinae in general appearance. The
petiole consists of a single scale and the poison glands produce formic acid, which some
genera, particularly Formica, can squirt a considerable distance. In many Formica species
naked pupae are common while in other genera they are normally enclosed in cocoons.
Formica is the dominant genus with seven definite species. Three Camponotus, two Lasius
and one Brachymyrmex species were also recorded.
(12) Brachymyrmex depilis Emery
This minute (c 1.5 mm), pale brown species was taken once on Mt. Tolmie under a small
piece of wood and an adjacent stone. It may be quite widespread, but like Solenopsis molesta
it is easily overlooked because of its small size and subterranean habits.
(13) Lasius pallitarsis Provancher (syn. L. sitkaensis Pergande)
A relatively robust species. Workers are about 3.5 mm long and pale brown in colour. It is
widespread, and most often found under stones in semi-shaded or shaded habitats. Workers
sometimes forage above ground and even up small trees. Alates were seen in September.
(14) Lasius alienus Forster
This small (2.5-3.0 mm), brown species was found two or three times in partially shaded
situations. It is probably widespread. Its behaviour in North America contrasts with that in
Western Europe where it favours an open heathland habitat. Mature Lasius colonies are
usually populous, with several thousand workers.
(15) Camponotus modoc Wheeler
The western equivalent of the carpenter ant, C. pennyslvanicus. Workers are up to 13 mm
long, and dull black with reddish legs. It is probably the commonest Camponotus species in
Victoria itself, sometimes occuring in gardens. It is uncommon by the roadside in the Pilkey
Point area of Thetis Island. Nests are usually situated in or under wood. They are fairly
populous, estimated to contain from several hundred to over a thousand workers. Workers
were often observed climbing trees, probably to tend aphids. On 11th May, 1988, a nuptial
flight took place on the University of Victoria campus. Most colonies released only a few
dozen alates, but one produced at least 1000 (quite possibly more than that number), an
impressive sight as they covered at least 20 square yards of vegetation in their attempts to get
airborne.
(16) Camponotus laevigatus F Smith
The workers of this shining black species are smaller, faster and more agile than those of
C. modoc. Two or three colonies of moderate size were found in clearings in Douglas fir
forest on Thetis Island. The nests occur in fallen logs.
(17) Camponotus vicinus Mayr
Another very large species, the workers display a more marked polymorphism than those
of C. modoc. They are normally bicolored, the red thorax contrasting with the dark head and
dull black gaster, but the workers of a small colony from a shaded site on Thetis Island were
entirely dark. As these were otherwise not separable from other specimens they are likely to
belong to this species. Nests are normally located beneath logs or stones and are of moderate
size. It was common in Douglas fir forest on Thetis Island but the colony found on Mt.
Tolmie was well away from trees. It appears to be largely nocturnal which makes it much less
conspicuous than C. modoc. Alates were present in Thetis Island nests in early September,
and these possibly over-winter and fly in early summer.
10 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
C d
Figures 2a-b. Alitrunk in profile of workers of Myrmica.
Figure 2a. Myrmica emeryana group sp.
Figure 2b. Myrmica incompleta.
Figures 2c-g. Alitrunk in profile and dorsal view of petiolus of workers of Leptothorax.
Figure 2c. Leptothorax muscorum
Figure 2d. Leptothorax muscorum group sp. “uvicensis”
Figure 2e. Leptothorax rugatulus
Figure 2f. Leptothorax melanderi (?)
Figure 2g. Leptothorax nevadensis ('?)
Scale: 1 mm; arrows = important diagnostic characters.
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 11
Note —Two other very large Camponotus species could potentially occur in the Victoria
region. C. herculeanus and C. noveboracensis are closely allied to C. modoc, all worker
castes sharing the very robust form of that species, but being bicolored they are more likely
to be confused with C. vicinus. C. herculeanus tends to be the darker of the two. It has a
pubescent gaster, like C. vicinus. C. noveboracensis usually resembles typical C. vicinus in
having a brighter red thorax but with a shining gaster.
(18) Formica subnuda Emery
A conspicuous species, typically 6-8 mm long with head and thorax blood-red, gaster
black. Like most members of the F: sanguinea species group it is a facultative slave raider. F-
accreta and F: neorufibarbis slaves were seen, and these occasionally accompanied the F:
subnuda workers up trees to tend aphids. One colony had slaves of both species. It is fairly
common in suburban areas and Garry oak woodland, usually nesting in sunny situations in
stumps or under stones. Most colonies contained at least a few hundred workers.
(19) Formica obscuripes Forel
The only member of the F: rufa group seen. Workers are quite large, about 5-8 mm.
Majors have orange heads, but minors are darker, being almost a uniform blackish-brown. It
is very sparsely distributed in Victoria itself, building typical “wood ant” heaps of vegetable
debris in grassy areas around woodland borders. These contain tens of thousands of
workers.
(20) Formica accreta Francoeur
A fairly large (4-7 mm) black species, it is very like the European F: fusca but more
aggressive. Colonies of this and all the following species vary 1n size from several hundred to
a thousand or more workers. It is easily the most conspicuous ant in Victoria, being
abundant and almost universally distributed. The type locality is Royal Oak, a suburb of
Victoria. Several de-alate females were seen wandering over the ground in early September.
A pterergate was also collected.
(20a) Formica sp. “fuliginothorax”
This “species” may be synonymous with F: accreta as the only clear distinction is the
dark brown colour of F. “fuliginothorax”. Francoeur (1973) describes F: accreta as being
black or dark brown. F’. “fuliginothorax” was not, however, seen to associate with F: accreta
and no mixed colonies were found. It is much more sparsely distributed and seems to favour
different habitats— normally short turf or crumbling banks. More specimens are needed,
including alates.
(21) Formica pacifica Francoeur
A distinctly coloured species, with fine but dense bronze pubescence on the thorax and a
darker head and gaster. It has an interesting distribution, being almost entirely restricted to
urban areas. Nests normally occur between cracks in concrete, so it is commonest by
roadsides and in car parks. The only record from an even semi-natural habitat was at Clover
Point.
(22) Formica neorufibarbis Emery
This species is characteristically bicolored, with a blackish head and gaster, and red
thorax. Despite its robust build it is rather timid and it was taken only in the gardens of the
University of Victoria, where a couple of nests were found in stumps.
_ (23) Formica subpolita Mayr
Another robust species. It is darker in colour than F: neorufibarbis and has a charac-
teristically convex dorsal surface to the propodeum. Two workers were taken on short turf
above the cliffs near Beacon Hill Park.
(24) Formica lasioides Emery
The only member of the F neogagates species group to be found. It is rather variable in
size, colour and pilosity but is always shining, with at least a few erect hairs on its antennal
scapes. It is widespread in grassy habitats, including open oak woodland.
12 J. ENTOMOL. Soc. BriT. COLUMBEA 89, DECEMBER, 1992
Myrmecophiles
The ant cricket, Myrmecophila oregonensis Bruner, was observed on several occasions
near nests of F obscuripes and F. subnuda. Two ant mimics were also found. A bug (Nabis
sp.) was taken on Thetis Island, and an unidentified spider mimic of F: subnuda was seen on
Mt. Tolmie.
CONCLUSIONS
This study attempts to relate the ant fauna to habitat type. While it is provisional due to the
small number of sites visited and the influence of human perturbances, it should have some
predictive value for a more comprehensive survey. Of the natural habitats, the grass balds —
Garry oak woodland appears to have the richest fauna (13 species). This is not surprising
because of the high insolation at the soil surface, but it should be noted that this habitat was
by far the most intensively searched. South-facing clearings in Douglas fir forests are
probably com: «ine. he cooler red cedar forest has a much more limited ant fauna but is
notable for the presence of Stenamma diecki. Culivated and urban areas increase habitat
diversity and are of interest because of the presence of a number of species recorded from
truly “wild” areas, particularly Formica pacifica.
ACKNOWLEDGEMENTS
I am grateful to Cedric Collingwood for invaluable assistance with the identification of
material and to Barry Bolton for allowing me to examine specimens in the collection of the
British Museum (Natural History). I am also grateful to Cris Guppy of the Royal British
Columbia Museum for sending me available information on the ants of British Columbia.
Dr. Richard Ring of the University of Victoria, on behalf of the Entomological Society of
British Columbia, obtained the funding that made the publication of this paper possible.
Finally, I thank the Wickett family for taking me to Thetis Island.
REFERENCES
Beall, G. 1929. Observations on the ant cricket Myrmecophila oregonensis Bruner. Proc. B.C. Entomol. Soc. 26:
44-46.
Buckell, E.R. 1927. An annotated list of the ants of British Columbia. Proc. B.C. Entomol. Soc. 24: 30-34.
. 1932. A list of the ants of British Columbia. Proc. B.C. Entomol. Soc. 29: 22-25.
Collingwood, C.A. 1979. The Formicidae (Hymenoptera) of Fennoscandia and Denmark. Fauna Entomologica
Scandinavica. Vol. 8. Scandinavian Science Press Ltd., Klampenborg, Denmark.
Creighton, W.S. 1950. The Ants of North America. Bull. Mus. Comp. Zool. Harv. 104. 585 pp.
Francoeur, A. 1973. Revision taxonomique des espéces nearctiques du groupe fesca: genre Formica (Formicidae,
Hymenoptera). Mem. Soc. ent. Québ. 3. 316 pp.
. 1979. Formicoidea. In Danks, H.V. (ed.), Canada and its Insect Fauna. Mem. ent. Soc. Can. 108:
502-503.
Hagmeier, E.M. 1965. Ecology. In Natural History of Thetis Lake Area near Victoria, British Columbia. Thetis
Lake Park Nature Sanctuary Association. Report for 1965 of the Provincial Museum of Natural History and
Anthropology, Victoria, B.C. pp. 26-54.
Henderson, G. and R.D. Akre. 1986. Morphology of Myrmecophila manni, a myrmecophilous cricket (Orthoptera:
Gryllidae). J. Entomol. Soc. Brit. Columbia. 83: 57-62.
Kerr, D.P. 1951. The Summer Dry Climate of the Georgia Basin. Trans. R. Can. Inst. 29, Part 1. Ottawa.
McMinn, R.G., S. Eis, H.E. Hirvonen, E.T. Oswald and J.P. Senyk. 1976. Native vegetation in British Columbia's
Capital Region. Report BC-X-140. Canadian Forestry Service, Victoria, B.C.
Muesebeck, C.EW. 1951. Hymenoptera of America north of Mexico. Synoptic Catalog. Agriculture Monogr. 2:
778-875 (Family Formicidae by M.R. Smith). First supplement in 1958. Second supplement in 1967.
Nielsen, M.G. 1987. The ant fauna in Northern and Interior Alaska. A survey along the Trans-Alaskan Pipeline and
a few highways. Ent. News 98 (2): 74-88.
Pavlick, L.E. 1986. A naturalist’s guide to the botany of the Victoria Region. In Weston, J. and S. Stirling (eds.)
1986. The Naturalist’s Guide to the Victoria Region. Victoria Natural History Society. Victoria, B.C. 200 pp.
Roemer, H.L. 1972. Forest vegetation and environments on the Saanich Peninsula, Vancouver Island. Unpublished
Ph.D. thesis. University of Victoria, Victoria, B.C.
Sharplin, J. 1966. An annotated list of the Formicidae of central and southern Alberta. Quaest. ent. 2: 243-253.
_ J. Entromot. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 13
Attraction of Douglas-fir beetle,
spruce beetle and a bark beetle predator
(Coleoptera: Scolytidae and Cleridae)
to enantiomers of frontalin
B. STAFFAN LINDGREN
PHERO TECH INC., 7572 PROGRESS WAY, RR #5, DELTA, B.C. V4G 1E9, CANADA
ABSTRACT
In three separate experiments, Douglas-fir beetles, Dendroctonus pseudotsugae Hopkins,
preferred traps baited with either ($)-(-)- or racemic (R,S)-( + )-frontalin over those baited
with the (R)-( + )-enantiomer. Spruce beetles, D. rufipennis (Kirby), appeared to be attracted
equally to both the (S)-(-)- and (R)-(+ )-enantiomers, but low catches and high variance
made interpretation of the data tenuous. For both species racemic frontalin was as attractive
as the preferred enantiomer alone. The bark beetle predator, Thanasimus undatulus (Say),
was attracted preferentially to (S)-(-)-frontalin over (R)-(+ )- or (R,S)-(+ )-frontalin in a
Douglas-fir stand, while both enantiomers were equally attractive in a spruce stand.
Additional keywords: Dendroctonus pseudotsugae, Dendroctonus rufipennis, semio-
chemical, kairomones, Thanasimus undatulus, predator, trapping
INTRODUCTION
Biological activity of semiochemicals on insects may be maximal to particular enantiomeric
blends or restricted to single enantiomers. For example, the ambrosia beetle, Gnathotrichus
retusus (LeConte), responds to ($)-( + )-sulcatol, whereas the presence of (R)-(-)-sulcatol is
inhibitory (Borden et al. 1980a). Similarly the pine engraver, [ps pini (Say), is attracted by
(R)-(-)-ipsdienol, but inhibited by (S)-( + )- ipsdienol in California (Birch et al. 1980). The
striped ambrosia beetle, Tiypodendron lineatum (Olivier), produces and responds to
1(R),4¢S),5(R),7(R)-( + )-lineatin, whereas the 1($),4(R),5(S),7(S)-(-)-enantiomer is inert
(Borden et al. 1980b).
Numerous studies on the chemical ecology of the Douglas-fir beetle, Dendroctonus
pseudotsugae Hopkins, and the spruce beetle, D. rufipennis (Kirby), have been conducted
over the last two decades. Both species produce !-methylcyclohex-2-en-I- ol (MCOL) and
3-methylcyclohex-2-en-l-one (MCH), and 1,5-dimethyl-6,8- dioxabicyclo[3.2.1]octane
(frontalin) (Kinzer et al. 1971; Libbey et al. 1983; Gries et al. 1988; G. Gries!, pers. comm. ).
Both species also exhibit enantiospecific response to MCOL (Lindgren et al. 1992; J.H.
Borden!, pers. comm.) However, there is no published information on the response by these
beetles to enantiomers of frontalin. Thus, the objective of this study was to determine the
response of Douglas-fir beetles and spruce beetles to the two frontalin enantiomers alone and
in combination.
MATERIALS AND METHODS
Enantiomers of frontalin (chemical purity >97 %; optical purity 97 % for both enantiomers)
were purchased from Simon Fraser University. Lures consisted of frontalin-filled capillaries
(45 x 1 mm i.d.) placed in 400 pl polyethylene Eppendorf centrifuge tubes. A 4 mm-
diameter hole was cut in the side of each Eppendorf, and the devices suspended in Lindgren
funnel traps so that the hole faced downward. In this manner entry of rainwater into the
Eppendorf tubes was minimized. The release rate of each enantiomer was estimated at 0.5
mg/24 h @ 24 °C by measuring the drop of the meniscus.
Treatments in all experiments consisted of: (1) (R)-(-)-frontalin, (2) (S)-(+ )-frontalin,
and (3) (R)-(-)- and (S)-(+ )-frontalin (one capillary each). In this manner the release rate of
each enantiomer was held constant among treatments. In the first experiment, an unbaited
control was also included as a fourth treatment. All experiments utilized 8-unit multiple-
14 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
funnel traps (Lindgren 1983) (Phero Tech Inc. Delta, B.C.). A2 X 2.cm piece of dichlorvos-
impregnated wax bar was placed in the collection jar of each trap to prevent predatory beetles
and ants from destroying the captured bark beetles.
Douglas-fir beetle.
The first of three experiments was conducted at the University of British Columbia
Research Forest, Maple Ridge, B.C., as a three-block, randomized complete block design
experiment, with two time replicates, May 4-11, and May 11-18, 1984. Treatment positions
were rerandomized for the second time replicate. The second experiment was conducted at
the Manning Creek Forest Road, about 30 km NW of Merritt, B.C., as a seven-block,
randomized complete block design experiment May 7-20, 1985. The third experiment was
conducted at the Manning Creek Forest Road as a four-block, randomized complete block
design experiment, with two time replicates, May 24-27 and May 27-June 4, 1985. -
Treatment positions were rerandomized for the second time replicate. Captured insects were
collected and stored in a freezer until counted and their sex determined (Jantz and Johnsey
1964; Lyon 1958).
Spruce beetle.
Two seven-block randomized complete block design experiments were conducted along
the Miner Creek Forest Road, about 30 km SW of Merritt, B.C., June 7-18, and June 18-21,
1985. Captured insects were collected, stored and their sex determined as described above.
Statistical Analyses.
The data were subjected to analysis of variance (a =0.05), and the means separated by
Tukey’s Test (a=0.05). All data were transformed as x’ = log, (x + 1) to remove hetero-
geneity of variances before analysis. Proportion data in the third Douglas-fir beetle
experiment were transformed as x’ = arcsin\/p, where p is a proportion, and 0 was replaced
by '/an and | by 1-('/4n) (Zar 1984). The first and third Douglas-fir beetle experiments, and
the spruce beetle experiments, were analyzed as replicated randomized complete blocks.
Table 1
Response by Douglas-fir beetles to Lindgren funnel traps baited with enantiomers of frontalin.
Malcolm Knapp Research Forest, Maple Ridge, B.C., 1984 (n=6).
MEAN NUMBER (+ SD) DOUGLAS-FIR
TREATMENT BEETLES CAPTURED@
UNBAITED CONTROL 0.0 (+0.0)a
(R)-( + )-FRONTALIN 0.2 (+0.4)ab
(S)-(-)-FRONTALIN 2.0(+2.1)b
(R,S)-( + )-FRONTALIN 1.8(+1.8)b
aMeans followed by the same letter not significantly different, analysis of variance and Tukey’s test
(a =0.05)
RESULTS AND DISCUSSION
Douglas-fir beetle. The data analyses from the first experiment, which was conducted in the
coastal Douglas-fir zone, indicated that (R)-(-)-frontalin is the attractive enantiomer (Table
1). Although the (S)-( + )-enantiomer was not significantly different at the stated probability
level from any other treatment in this experiment, the Tukey HSD probability was p=0.051
and p=0.055 when comparing (S)-(+ )-frontalin to (R)- (-)- and (R,S)-(+ )-frontalin,
respectively. The two experiments conducted in the interior Douglas-fir zone showed clearly
that (R)-(-)-frontalin is the attractive enantiomer for male Douglas-fir beetles, while the (S)-(
+ )-enantiomer appears to be relatively inactive (Tables 2-3). Thus, male Douglas-fir beetles
in both the coastal and interior Douglas-fir zones responded similarly to frontalin enan-
tiomers. Female Douglas-fir beetles were attracted mainly to the (R)-(-)-enantiomer in both
the second and third experiment (Tables 2-3). The treatment effect for female catch in the
second experiment approached significance (p =0.079), and was highly significant in the
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 15
third experiment. There was no treatment effect on sex ratio, expressed as proportion of
females, in the third experiment (Table 3). Only two females were captured in the first
experiment, both of which responded to traps baited with both enantiomers. Traps baited
with both enantiomers tended to capture the highest numbers of beetles of both sexes in all
three experiments, indicating that (S)-(+ )-frontalin may have some activity.
Table 2
Response by Douglas-fir beetles and the clerid predator Thanasimus undatulus to Lindgren funnel
traps baited with enantiomers of frontalin. Manning Creek Road, Merritt Forest District, B.C., May
7-20, 1985 (n=7).
MEAN NUMBER (+SD) DOUGLAS-FIR
BEETLES AND CLERIDS CAPTURED?
TREATMENT MALES FEMALES TOTAL CLERIDS
(R)-( + )-FRONTALIN 1.0a O.la l.la O.la
G12) (+0.4) (+1.2) C04)
(S)-(-)-FRONTALIN 16.7b Brod 20.0b 2.9b
(21-2) (257) (+ 26.7) (+ 2.6)
(R,S)-( + )-FRONTALIN 12.0b 4.la 16.1b 0.6a
(Gary es (+4.2) (+ 15.6) (+0.8)
aMeans followed by the same letter not significantly different, analysis of variance and Tukey’s test
(a =0.05).
Table 3
Response by Douglas-fir beetles to Lindgren funnel traps baited with enantiomers of frontalin.
Manning Creek Road, Merritt Forest District, B.C., May 20-27, 1985 (n=8).
MEAN NUMBER (+ SD) DOUGLAS-
FIR BEETLES CAPTURED2 PERCENT
TREATMENT MALES FEMALES TOTAL FEMALES
(R)-( + )-FRONTALIN Joa 3.8a 11.3a 37.4a
(+ 6.0) (42352) (+8.1) (+31.8)
(S)-(-)-FRONTALIN 32.6b 15.9b 48 .5b 32.6a
(+ 39.8) (+ 19.3) (+59.0) CESa1)
(R,S)-(+ )-FRONTALIN 43.6b 21.1b 64.8b 28.9a
(+ 30.3) (+ 20.7) (+ 50.3) O47)
aMeans followed by the same letter not significantly different, analysis of variance and Tukey’s test
(a =0.05)
Spruce beetle. Catches of spruce beetles were extremely low and variable (Table 4). Very
few insects were captured by any treatment, although one trap baited with (S)- (+ )-frontalin
captured 54 beetles in the first experiment. There were no significant treatment effects, and
no interactions, in these experiments. Based on these limited data, it appears that spruce
beetles respond to both enantiomers. Further experiments are needed to confirm this, as well
as to determine geographic variation in the response.
Clerid beetles, Thanasimus undatulus (Say), were captured in sufficient numbers for
statistical analysis in the second Douglas-fir beetle experiment and in the spruce beetle
experiment. Significantly more clerids were captured in the traps baited with (R)-(-)-
frontalin than to either of the treatments containing (S)-(+ )-frontalin in the Douglas-fir
beetle experiment (Table 2), whereas there were no significant differences among the
treatments in the spruce beetle experiments. This may indicate some level of behavioral or
physiological adaptation, or possibly genetic selection, in clerids predominantly responding
to kairomones from a single prey species. Herms et al. (1991) suggested that the related
Thanasimus dubius (F.) may select for changes in the pheromone system of its prey, [ps pini
16 J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
(Say), which both exhibited considerable inter- and intrapopulational variation in their
response to enantiomers of ipsdienol. However, in the experiments reported here the
numbers of clerids captured were low, so that additional experiments would be needed to be
certain that clerid response to their prey kairomones are enantiospecific, and if such
specificity is tied to the pheromone production of its prey.
Table 4
Response by spruce beetles and the clerid predator Thanasimus undatulus to Lindgren funnel traps
baited with enantiomers of frontalin. Miner Creek Road, Merritt Forest District, B.C., June 7-21, 1985
(n= 14).
MEAN NUMBER (+SD) SPRUCE BEETLES
AND CLERIDS CAPTURED@
TREATMENT MALES FEMALES TOTAL CLERIDS
(R)-( + )-FRONTALIN 2.9 Zod. 5.6 2.0
(27.6) G=6.6) (+ 14:1) (23:0)
(S)-(-)-FRONTALIN 0.8 1.1 1.9 1.6
(1.0) (3 1 37)) (22.3) (2.158)
(R,S)-( + )-FRONTALIN 1.5 1.5 3.0 As3
(222.1) Ce 2) (+4.6) (+6.8)
aThere were no significant differences among treatments, analysis of variance (a =0.05)
If the lack of treatment effects in the spruce beetle experiments is real, enantiospecific
responses to frontalin may be one of the mechanisms whereby these bark beetles maintain
species segregation. However, interspecific cross attraction to semiochemicals produced
from infested logs has been demonstrated for these species (Chapman and Dyer 1969). For
both species, synthetic racemic frontalin can be used in management applications, since it is
equally attractive as either enantiomer.
ACKNOWLEDGEMENTS
I thank M. Merkens for technical assistance, A.C. Oehlschlager and B.D. Johnston for
synthesizing the frontalin enantiomers, and D.R. Miller for review of the manuscript. The
research was supported by a research grant and an Industrial Post-Doctoral Fellowship to the
author from the Science Council of B.C.
NOTE
! Department of Biological Sciences, Simon Fraser University, Burnaby, B.C.
REFERENCES
Birch, M.C., D.L. Light, D.L. Wood, L.E. Browne, R.M. Silverstein, B.J. Bergot, G. Ohloff, J.R. West, and J.C.
Young. 1980. Pheromonal attraction and allomonal interruption of /ps pini in California by the two enantiomers
of ipsdienol. J. Chem. Ecol. 6: 703-717.
Borden, J.H., J.R. Handley, J.A. McLean, R.M. Severe L. Chong, K.N. Slessor, B.D. Johnston, and H.R.
Schuler. 1980a. Enantiomer-based specificity in pheromone communication by two sympatric Gnathotrichus
species (Coleoptera: Scolytidae) J. Chem. Ecol. 6: 445-456.
Borden, J.H., A.C. Oehlschlager, K.N. Slessor, L. Chong, and H.D. Pierce, Jr. 1980b. Field tests of isomers of
lineatin, the aggregation pheromone of Trypodendron lineatum (Coleoptera: Scolytidae) Can. Entomol. 112:
107-109.
Chapman, J.A., and E.D.A. Dyer. 1969. Cross attraction between the Douglas-fir beetle (Dendroctonus pseudo-
tsugae Hopk.) and the spruce beetle (D. obesus (Mann.)). Can. Dept. Fish. For., Bi-Monthly Res. Notes 25:31.
Gries, G., H.D. Pierce, Jr, B.S. Lindgren, and J.H. Borden. 1988. New techniques for capturing and analyzing
semiochemicals for scolytid beetles (Coleoptera: Scolytidae). J. Econ. Entomol. 81: 1715-1720.
Jantz, O.K., and R.L. Johnsey. 1964. Determination of sex of the Douglas-fir beetle Dendroctonus pseudotsugae
Hopkins (Coleoptera: Scolytidae). Can. Entomol. 96: 1327-1329.
Herms, D.A., R.A. Haack, and B.D. Ayres. 1991. Variation in semiochemical-mediated prey-predator interaction:
Ips pini (Scolytidae) and Thanasimus dubius (Cleridae). J. Chem. Ecol. 17: 1705-1714.
Kinzer, G.W., A.E Fentiman, Jr, J.L. Foltz, and J.A. Rudinsky. 1971. Bark beetle attractants: 3-Methyl-2-
cyclohexen-l-one isolated from Dendroctonus pseudotsugae. J. Econ. Entomol. 64: 970-971.
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 17
Libbey, L.M., A.C. Oehlschlager, and L.C. Ryker. 1983. 1-Methylcyclohex-2-en-l-ol as an aggregation phe-
romone of Dendroctonus pseudotsugae. J. Chem. Ecol. 9: 1533-1541.
Lindgren, B.S. 1983. A multiple funnel trap for scolytid beetles (Coleoptera). Can. Entomol. 115: 299-302.
Lindgren, B.S., G. Gries, H.D. Pierce, Jr., and K. Mori. 1992. Dendroctonus pseudotsugae Hopkins (Coleoptera:
Scolytidae): Production of and response to enantiomers of l-methylcyclohex-2-en-l-ol. J. Chem. Ecol. 18:
1201-1208.
Lyon, R.L. 1958. A useful secondary sex characteristic in Dendroctonus bark beetles. Can. Entomol. 90: 582-584.
Zar, J.H. 1984. Biostatistical Analysis. Prentice-Hall, Inc., Englewood Cliffs, NJ.
18 J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
Establishment of Phyllonorycter mespilella (Hiibner)
(Lepidoptera:Gracillariidae) and its parasitoid,
Pnigalio flavipes (Hymenoptera: Eulophidae), in fruit
orchards in the Okanagan and Similkameen Valleys of
British Columbia
J. E. COSSENTINE AND L. B. JENSEN
AGRICULTURE CANADA RESEARCH STATION SUMMERLAND, BRITISH COLUMBIA VOH 1Z0
CONTRIBUTION # 795
ABSTRACT
In 1988, a leafminer, Phyllonorycter mespilella (Hiibner) (Lepidoptera:Gracillariidae) was
found for the first time in commercial fruit orchards in the Okanagan and Similkameen
valleys of British Columbia after apparently moving across the international border from
Washington State. Leafminer infestations and parasitoid-induced-leafminer-mortalities were
assessed in widespread surveys in the two orcharding areas from 1988 to 1990. Pnigalio
flavipes (Hymenoptera:Eulophidae) was the primary parasitoid of the leafminer pest. Three
additional parasitoid species associated with the leafminer host in 1990 were: a Sympiesis
species, an Eulophus species and a Cirrospilus species (Hymenoptera:Eulophidae). Parasi-
tism reduced intraseasonal leafminer population increase as parasitoid-induced-mortality in
the first leafminer generation of 1989 and 1990 was negatively correlated with leafminer
density in both the second and third generations of the same year.
Key words: Insecta, Phyllonorycter mespilella, \eafminer, parasitism.
INTRODUCTION
The leafminer pest of several economically important tree fruit-crops in western North
America, previously misidentified as Phyllonorycter elmaella Doganlar & Mutuura (Lep-
idoptera:Gracillariidae), has been identified as Phyllonorycter mespilella (Hiibner) by J.-F
Landry (Centre for Land and Biological Resources Research, Ottawa) and D. Wagner
(University of Connecticut, Storrs). Although low infestations of this leafminer cause
minimal apple damage, severe infestations in apple orchards can result in premature
ripening, leaf and fruit drop, reductions in apple firmness, size, color and storage life, and
reduced foliar absorption of growth regulators (Hoyt 1983).
This leafminer was a minor orchard pest throughout the Pacific Northwest of the United
States until the species developed resistance to commonly used organophosphate and
chlorinated-hydrocarbon orchard chemical sprays (Hoyt 1983). The only chemical currently
registered for successful control of the resistant pest species on apple in the United States is a
carbamate; a chemical that is toxic to predaceous mites and therefore disrupts established
nonchemical integrated mite management programs.
Parasitism has been reported to cause major mortality in Phyllonorycter spp. (Barrett
1988, Doganlar and Beirne 1980, Pottinger and LeRoux 1971). Pnigalio flavipes (Ashmead)
(Hymenoptera:Eulophidae), the key parasitoid of the leafminer pest in Washington State
(Barrett 1988), has been shown to have the potential to reduce the leafminers’ intraseasonal
population increase and to keep its host’s density below treatment levels (Barrett and Brunner
1990).
Phyllonorycter elmaella was described in British Columbia on apples in the Vancouver
area (Doganlar and Mutuura 1980), however the species has not been recorded in areas of
commercial orcharding in the Okanagan and Similkameen valleys. This study reports
surveys conducted from 1988 to 1990 to verify the establishment and spread of P. mespilella
and its associated parasitoids, into apple orchards in the interior of British Columbia.
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
e.
QO
8
xxx
KX
Swe
Sav,
SYS
RS x
oe:
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DOM
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ang
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Figure 1. Area of the Okanagan and Similkameen valleys included in the leafminer survey.
20 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
MATERIALS AND METHODS
In the first P mespilella generation of 1988, three orchards in Osoyoos, where the original
infestation was found, and in the second generation, 13 orchards from Osoyoos to Kaleden
were surveyed. In the third generation of 1988, 33 orchards from Osoyoos to Vernon
(Okanagan Valley) as well as eight orchards in Keremeos and Cawston (Similkameen
Valley) were surveyed in a similar fashion (Fig. 1). In 1989 and 1990 from 28 to 42 of the
same orchards in the two valleys were surveyed in each of the three leafminer generations
(Table 1). Surveys were conducted during the tissue-feeding stage of each leafminer
generation. All orchard sites, save one in each of the Okanagan and Similkameen Valleys,
were exposed to azinphosmethyl] treatments for summer codling moth control.
Table 1
Mean leafminers found per minute of searching time in orchards in the Similkameen and Okanagan
Valleys of British Columbia, 1988-1990.
Gen Mean mines found per minutec + sd
Orchard Area 1988 (n)4 1989 (n) 1990 (n)
(km north)?
Keremeos ] —e 1743" 1782 (8) P72 eae (8)
(20 km) 2 — 133° = 1323) 5, 19° 22 4735) (8)
3 3.49 + 4.79 (8) 2.59 2 2.48)(8) 61.91 + 24.91 (8)
Osoyoos 1 0.10 + 0.00 (3) 0.99 + 1.07 (6) 1.29). 9 O252(5)
(0 km) Z 1212250573. (6) 0.43 + 0.42 (6) 2 Sos 2)
3 6.59 + 4.10 (6) 5.84 + 6.40 (6) 30.25° = 23.9 94(5)
Oliver 1 O18 += 0:11) 0:75) E038)
(20 km) 2, 0.14 + 0.16 (5) 0.07 + 0.08 (6) 1.60 + 0.83 (5)
3 0.45 + 0.37 (5) 1.52 + 0.94 (6) 23.25) = ekOr22( (5)
Vaseux Lake ] — 1.22 + 1.85 @) 0.07 + 0.08 (3)
to Kaleden 2 0.28: 0.25 (2) 0.15 + naf(1) 0.43 + 0.33 (3)
(31-43 km) 3 0.30 + 0.30 (3) 1.50 + 0.85 (3) 10.08 + 11.04 (3)
Penticton 1 _ 0.08 + 0.15 (4) 0.49 + 0.78 (4)
(49 km) 2 — 0.14 + 0.21 (4) 9.24 + 5.95 (4)
3 0.03 + 0.05 (4) 1.05 + 1.38 (4) 43.44 + 47.84 (4)
Naramata l 0.42 + 0.72 (3) 5.62 + 6.59 (3)
(64 km) 2 — 0.50 + 0.74 (3) 27.62 + 26.84 (3)
3 0.02 + 0.05 (3) 1.08 + 0.88 (3) 129.50 + 69.68 (3)
Summerland 1 — — 0.13 + 0.14 (3)
(67 km) 2 — _ 1.07 + 1.11 (3)
3 0.00 + 0.00 (3) 0.08 + 0.08 (3) 12.83 + 11.58 (3)
Peachland to 1 -- — 0.00 + 0.00 (2)
Westbank 2 _ | — 0.40 + 0.57 (2)
(87-92 km) 3 0.00 + 0.00 (2) 0.00 + 0.00 (2) 4.73 + 2.86 (2)
Kelowna 1 _ — 0.00 + 0.00 (3)
(92 km) 2 — — 0.00 + 0.00 (3)
3 0.00 + 0.00 (3) 0.00 + 0.00 (3) 1.10 + 0.43 (3)
Vernon 1 — — 0.01 + 0.03 (4)
(137 km) 2 — — 0.21 + 0.39 (4)
3 0.00 + 0.00 (4) 0.00 + 0.00 (4) 11.26 + 20.36 (4)
4 Kilometers north of Canada/United States border
b Leafminer generation
© Derived from 10 minute visual search
4d Number of orchards included in mean
€ Unrecorded
f Only one orchard surveyed therefore no standard deviation of mean
J. ENTomo _. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 71
An orchard survey involved a ten-minute visual search by two individuals experienced in
mine recognition. In 1990, the survey time was reduced to two-minutes in orchards where
more than 50 mines were counted per minute. Leaves in the orchards were examined
continuously during the time period, both on the upper and lower surfaces because
sapfeeders (the early feeding stage of the leafminer) are visible only on the underside of the
leaf. All leafminer-infested leaves observed were collected and taken to the laboratory. Each
mine was examined under a stereomicroscope and the stages of leafminers and parasitoids
present were recorded. Empty mines, whose previous occupants could not be determined,
were included in total mine counts in the first generation only.
Leafminers were recorded as parasitized when an ectoparasitoid egg, larva, pupa, or
adult was found in the mine. A round parasitoid exit hole on the surface of the mine was
recorded as parasitized in the first generation count only. Dead leafminers were considered
to have been host fed or stung.
Table 2
Mean percent parasitism of leafminers in the Similkameen and Okanagan Valleys, 1988-1990.
Gen> Mean percent parasitism + sd
Orchard Area 1988 (n)¢ 1989 (n) 1990 (n)
(km north)?
Keremeos l —d 41.36 + 15.46 (8) 26.19 + 16.66 (8)
(20 km) 2 — 31.25 + 24.15 (8) 25.56 + 13.59 (8)
3 17.10 + 11.53 (8) 16.43 + 10.78 (8) 30.11 + 13.58 (8)
Osoyoos 1 0.00 + 0.00 (2) 64.39 + 29.02 (6) 40.52 + 16.44 (5)
(O km) 2 38.36 + 28.27 (6) 11.10 + 12.31 (6) 22.91 + 15.39 (5)
3 61.23 + 20.99 (6) 23.09 + 10.30 (6) 21.71 + 2.69 (5)
Oliver l — 37.22 37:14 6) 33.96 + 16.59 (5)
(20 km) 2 4.17 + 7.21 (3) 5.00 + 10.00 (6) 17250: =4°6.53 ©)
3 37.14 + 18.42 (5) 33.94 + 20.38 (6) 25.67 + 13.38 (5)
Vaseux Lake Il — 32.09 + 27.85 (3) 16.67 + 23.57 (2)
to Kaleden 2 nae 0.00 + na (1) 50.00 + 16.67 (3)
(31-43 km) 3 na 25.84 + 17.36 (3) 35.26 + 13.09 (3)
Penticton l — 16.67 + na (1) 1.52 + 3.03 (4)
(49 km) 2 — 5.56 + 7.86 (2) 37.08 + 10.38 (4)
8) 0.00 + na (1) 34.28 + 16.79 (2) 14.30 + 7.15 (4)
Naramata | — 36.00 + na (1) 6.32, 7517.)
(64 km) 2. — 5.56 + 7.86 (2) 18.12 + 12.36 (3)
3 0.00 + na (1) 17.33 + 20.17 (3) 16.54 + 2.45 (3)
Summerland 1 = d 22.22 + 38.49 (3)
(67 km) 2 — d 39.39 + 17.91 (3)
3 na 0.01 + 0.00 (2) 31802* 16:07 (3)
Peachland to 1 — d na
Westbank 2 — d SiicOO) se na (1)
(87-92 km) 3 na na 9.26 = 1.8602)
Kelowna 1 — d0.00 + na (1)
(92 km) 2 — d 625. na (1)
3 na na 3.44 + 6.89 (4)
Vernon l — d0.00 + na (1)
(137 km) 2 — d 0.00 + na(1)
3 na na 4.46 + 6.31 Q)
4 Kilometers north of Canada/United States border
> Leafminer generation
© Total orchards included in mean4Unrecorded
© Only one orchard surveyed or no leafminer found, therefore percent parasitism irrelevant
22 | J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
To compare the estimate of leafminer density using timed mine surveys with that
obtained by randomly collecting 100 leaves (Barrett and Brunner 1990, Hoyt 1983), both
techniques were carried out at 34 orchard sites in the two valleys in the third generation of
1989 as well as the first generation of 1990. The percentage of mines per 100 leaves was
compared with the number of mines found per 10 min per person using a Spearman
correlation (SAS 1985).
Pheromone traps baited with spotted tentiform leafminer, Phyllonorycter blancardella
(Fabricius), pheromone were hung in sample orchards where the leafminer had not
previously been recorded. Samples of adult parasitoids were fixed in alcohol and sent to the
Biosystematics laboratory in Ottawa for identification.
Table 3
Mean percent dead leafminers in orchards of the Similkameen and Okanagan Valleys, 1988-1990.
Gen> Mean percent dead leafminers + sd
Orchard Area 1988 (n)¢ 1989 (n) 1990 (n)
(km north)?
Keremeos 1 —d 8.92 + 11.40 (8) 11.93 + 9.15 (8)
(20 km) 2 — 10.82 + 10.08 (8) 12.60 + 7.08 (8)
3 — 51.21 + -13225°(8) 38.82 + 7.67 (8)
Osoyoos | 0.00 + 0.00 (8) 10.68 + 13.90 (6) 17.59 + 10.83 (5)
(O km) 2 9.04 + 4.69 (6) 33.56 + 24:75: G6) LO%14 7 = 9282 (5)
3 — 50.94 + 14.05 (6) 47 Al SIS)
Oliver 1 — 40.56 + 41.11 (6) 13/52. 783. (6)
(20 km) 2 0.00 + 0.00 (3) 55.00 + 52.60 (4) 18.47 + 10.10 (5)
3 — 44.11 + 17.69 (6) 43.75 + 1.44(5)
Vaseux Lake 1 — 45.15 + 48.06 (3) 33.33 + 47.14 (2)
to Kaleden 2 0.00 + na& (1) 66.67 + na¢ (1) 8.15 = «7.14 GB)
(31-43 km) 3 — 27.88 + 8.20 (3) 31.32 + 18.57 (3)
Penticton 1 — 0.00 + 0.00 (1) 3.03 + 6.06 (4)
(49 km) 2 — 0.00 + 0.00 (2) 28.15 + 4.01 (4)
3 — 25.13-+. $)135:(2) 31.37 2 Y735 G4)
Naramata 1 — 16.00 + na (1) 7.91 + 6.03 (3)
(64 km) 2 — 3.70: 3.24.2) 12.58 +. 4.15 @G)
3 — 13.45 = 1217-6) 36.66 + 5.38 (3)
Summerland 1 — — 0.00 + 0.00 (3)
(67 km) 2 — — 9.73 + 8.43 (3)
3 na 58.33 + 11.79 (2) 21.47 + 10.02 (3)
Peachland to 1 — na
Westbank 2 — — 0.00 + na (1)
(87-92 km) 3 na na 14.82 + 5.24 (2)
Kelowna 1 — a 0.00 + na (1)
(92 km) 2 _ _ 0.00 + na (1)
3 na na 4.49 + 8.98 (4)
Vernon 1 — — 0.00 + na (1)
(137 km) 2 — — 0.00 + na (1)
3 na na 3.57 =~ 505 2)
@ Kilometers north of Canada/United States border
> Leafminer generation
© Total orchards included in mean
4 Unrecorded
© Only one orchard surveyed or no leafminer found therefore percent parasitism irrelevant
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 23
RESULTS AND DISCUSSION
A visual inspection of a defined number of randomly sampled leaves per orchard site (Barrett
and Brunner 1990, Hoyt 1983) was not used as a survey technique because very low
infestations could easily be left unrecorded using this method. The timed mine count used in
the survey was significantly correlated with the mine count in randomly collected leaves (R
=0.82, P=0.0001, n = 67). Therefore, we conclude that the timed survey was realistic
both in terms of finding extremely low infestations as well as estimating mine density.
In 1988, low infestations of the P. mespilella were widespread in surveyed orchards in
Keremeos and Cawston in the southern Similkameen Valleys, and from Osoyoos to
Naramata in the Okanagan Valley (approximately 20 to 23 km and 0 to 64 km N of the
international border respectively) (Table 1). The leafminer was found in two of the three
Osoyoos orchards surveyed in the first generation of 1988, suggesting that the species may
have been present in the Okanagan valley by the Fall of 1987. Leafminer infestations
decreased in density in orchards from the S to N of the Okanagan Valley (Table 1),
suggesting that the species crossed the international border in the interior of the province.
Pnigalio flavipes, the primary tentiform leafminer parasitoid species in Washington State
(Barrett 1988) and the second most dominant Phyllonorycter parasitoid in Utah (Barrett and
Jorgensen 1986) was found in 87% (n= 101 mines) of the leafminer hosts in the southern-
most orchard surveyed in the Okanagan Valley in 1988. Pnigalio flavipes was not listed as
one of the 12 parasitoid species reared from the P. elmaella in the Vancouver area of British
Columbia from 1976 to 1977 (Doganlar and Beirne 1980) indicating that this species also
crossed the international border from Washington State orchards. No parasitism was found N
of Oliver in 1988 (Table 2), however leafminer infestations were so low from Oliver to
Summerland that it is possible that the parasitoid was present but not intercepted.
In 1989, leafminers were not found in pheromone or visual orchard surveys north of
Summerland and Naramata. The density of leafminer infestations, as determined by mines
found per minute, remained low throughout the south Okanagan and Similkameen Valleys
(Table 1) even though parasitism in these regions was as high as 64.39 + 29.02 percent
(Table 2). Multiparasitism rather than superparasitism may have been what was evident in
orchards with high rates of parasitism.
In 1990, low numbers of the P. mespilella were found as far N as Vernon (approximately
137 km north of the international border) (Table 1). The highest leafminer counts were found
in the Naramata survey area, however even these numbers had not reached the treatment
threshold of one, two or five mines per leaf in the first, second or third leafminer generations
respectively, as recommended for control of P mespilella for Washington State growers
(Hoyt 1983).
Three additional parasitoid species were identified in survey orchards from Osoyoos to
Summerland in 1990. The second most abundant parasitoid was identified as a Sympiesis sp.
(Hymenoptera: Eulophidae) and the remaining two parasitoids as Eulophus sp. and
Cirrospilus sp. (Hymenoptera:Eulophidae). Percent parasitism per species was not deter-
mined as not all of the parasitoids survived after the survey mines had been opened and
inspected.
The percentage of dead leafminers in the 1989 and 1990 surveys was generally high in
infested areas (Table 3) (3.57 to 51.21% in the third generation). Adult Pnigalio species can
kill host larvae by stinging the host while ovipositing, as well as by feeding on the larvae.
Van Driesche and Taub (1983) also recorded death induced by Sympiesis marylandensis
stinging host larvae without oviposition. Percent parasitism combined with percent dead
leafminers (parasitoid-induced-mortality) is probably most indicative of the total impact
that the Pnigalio parasitoid is having on the leafminer host (Barrett 1988).
Phyllonorycter mespilella density in both the second and third generations in 1989 and
1990 was significantly (P=0.0001) and negatively correlated with parasitoid-induced-
mortality in the first generation of the same years (r= -0.68 and r= -0.63 respectively, n=
39). Parasitoid-induced-mortality in the second generation did not correlate significantly (P
>.05) with host density in the first, second or third generation. Parasitoid-induced-
mortality in the third generation was significantly negatively correlated with host density in
24 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
the second (r= -0.40, P=0.01, n= 39) and third generations (r= -0.34, P=0.03, n=39),.
Pnigalio flavipes in Washington State was found to respond to its tentiform leafminer host in
a density dependent manner (Barrett 1988) and to reduce the leafminer’s intraseasonal
population increase.
The P flavipes and its host survived the azinphosmethyl! codling moth treatments applied
in all but two of the orchards in this survey. Resistance of the parasitoid to commonly used
orchard pesticides and the parasitoid’s ability to reduce leafminer density in the second and
third generation supports parasitism as a realistic integrated strategem against leafminers
that is preferable to a carbamate-insecticide alternative.
High standard deviation of mean leafminer counts, percent parasitism and mortality
throughout the survey is indicative of the high variation between orchards even within a
given region. This variation should subside with time as the new pest and its parasitoid
complex become established throughout the orcharding area.
ACKNOWLEDGEMENTS
We thank Jim Troubridge for his field and laboratory assistance and the Centre for Land and
Biological Resources Research, Ottawa, Ont., for species identification.
REFERENCES
Barrett, B. A. 1988. The population dynamics of Pnigalio flavipes (Hymenoptera:Eulophidae), the major
parasitoid of Phylonorycter elmaella (Lepidoptera:Gracilariidae) in central Washington apple orchards. Ph.D.
dissertation, Washington State University, Pullman. 136 pp.
Barrett, B. A. and C. D. Jorgensen. 1986. Parasitoids of the western tentiform leafminer, Phyllonorycter elmaella
(Lepidoptera: Gracilariidae) in Utah apple orchards. Environ. Entomol. 15:635-641.
Barrett, B. A. and J. E Brunner. 1990. Temporal distribution of Phyllonorycter elmaella (Lepidop-
tera:Gracilariidae) and its major parasitoid, Pnigalio flavipes (Hymenoptera:Eulophidae) in Washington apple
orchards. Environ. Entomol. 19(2): 362-369.
Doganlar, M. and B. P. Beirne. 1980. Parasites of Phyllonorycter elmaella (Lepidoptera:Gracilariidae) on apple in
the Vancouver district, British Columbia. Can. Entomol. 112:314.
Doganlar, M. and A. Mutuura. 1980. A new species of Phyllonorycter Hbn. (= Lithocolietis Hbn.) (Lepidoptera:
Gracilariidae) from western North America. Can. Entomol. 112: 311-314.
Hoyt, S. 1983. Biology and control of the western tentiform leafminer. Proc. Wash. State Hort. Assoc. 79:115-118.
Pottinger, R. P. and E. J. LeRoux. 1971. The biology and dynamics of Lithocolletis blancardella (Lepidoptera:
Gracilariidae) on apple in Quebec. Mem. Ent. Soc. Can. 77. 437 pp.
SAS. 1985. SAS User’s Guide: Statistics, Version 5 ed. SAS Institute, Cary, N.C. 956 pp.
Van Driesche, R. G. and G. Taub. 1983. Impact of parasitoids on Phyllonorycter leafminers infesting apples in
Massachusetts, U.S.A. Prot. Ecol. 5:303-317.
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 25
Wireworm (Coleoptera: Elateridae) survey
_ in wheat-growing areas of
northcentral and northeastern Oregon!
H. H. TOBA AND J. D. CAMPBELL?
FRUIT AND VEGETABLE INSECT RESEARCH
USDA, ARS, YAKIMA, WASHINGTON 98902
ABSTRACT
A wireworm survey was conducted at 34 sites in wheat-growing areas of northcentral and
northeastern Oregon using a baiting technique. The highest mean number of wireworms
found at any site was 4.4 per bait of corn-wheat mixture. When wireworm numbers at each
site were used to estimate the population density, some sites had densities high enough to
cause yield reduction in spring wheat but not winter wheat. The species were predominantly
Ctenicera pruinina (Horn), Limonius californicus (Mannerheim), and Melanotus longulus
oregonensis (LeConte), with lesser numbers of Limonius infuscatus Motschulsky, Ctenicera
glauca (Germar), Aeolus mellillus (Say), and Dalopius sp. False wireworms (Tenebrionidae)
were also found at 10 sites, but their influence is uncertain.
INTRODUCTION
Wireworms, the larvae of click beetles, are destructive pests of cereal grain crops, feeding
on seeds, roots, and underground stems. In the Pacific Northwest, they include members of
the genera Aeolus, Agriotes, Ctenicera, Dalopius, Limonius, and Melanotus (Hyslop 1915,
Lane 1935). Much research has gone into developing treatment of seeds with pesticides for
protecting the crops and determining the short-term benefits derived from its use, such as
reduction in stand loss and increase in yield. Yet, because no long-term study has been
conducted, one can only assume that continued use of treated seeds suppresses wireworm
populations.
Many of the pesticides used for seed treatment in the past are no longer available, and the
availability of safe, effective and economical products in the future is uncertain. The
necessity of using treated seeds to control wireworms depends upon whether or not
damaging populations are present, for which the data are limited (Toba et al. 1985, 1988).
Soil sampling can be used to estimate wireworm densities (Jones and Shirck 1942, Onsager
1969). However, such sampling is laborious and time consuming, whereas baiting is less
demanding. Ward and Keaster (1977) developed a method of baiting by covering a buried
mixture of corn and wheat with a polyethylene sheet, resulting in significantly higher
attractancy to corn-infesting wireworms than did uncovered baits. Because such a baiting
technique merely indicates the absence or presence and relative abundance of wireworms,
Toba and Turner (1983) developed a method whereby a population density could be
estimated from the number of wireworms found at the baits.
This report documents the density of wireworm populations in various wheat-growing
areas of nine counties in northcentral and northeastern Oregon using a baiting technique.
MATERIALS AND METHODS
The survey was conducted in July and August 1981 at 34 sites. Each site was selected with
the advice and consent of individual ranchers who all practiced dryland farming, primarily
of wheat. The number of sites selected in each county was generally based on 1980 wheat
acreage as compiled by the Extension Economic Information Office, Oregon State Univer-
sity. Ranchers were also asked about the field history, particularly in regards to the use of
' Mention of a proprietary product does not constitute an endorsement by USDA.
? Eastern Oregon State College, La Grande, Oregon 97850.
26 J. ENTOMOL. Soc. BriT. COLUMBIA 89, DECEMBER, 1992
treated seeds for wireworm control. In several cases, the test sites were located in zones
believed to be affected by wireworms within the recent past. Fallow fields were favored over
planted fields. In the latter, an area of the field was left unplanted for the test sites.
Each study plot usually consisted of 16 bait spots in a 4-by-4 array, 15.2 m apart, except at
three locations in Union County; 2 m apart at location 39E,1S,9 and 4 m apart at the other
two locations. The baiting technique was similar to that of Toba and Turner (1983). At each
spot, a 20-cm-deep hole was dug with a 5-cm-diameter steel pipe driven into the ground
with a heavy hammer. Soil temperature readings were made about 5 cm below the bottom of
each of four holes with a YSI Model 42SC Tele-Thermometer (Yellow Springs Instrument
Co., Yellow Springs, Ohio) fitted with a soil probe. About 50 ml of a 1:1 mixture of presoaked
whole wheat and corn was placed in each hole and covered with the same soil that had been
removed. The seeds were untreated except for a fungicide (Vitavax) applied to wheat. The
spot was then covered with a 0.6-m? polyethylene sheet (4 mil thick) centered over the spot,
and the edges of the sheet were covered with soil.
About 21 d later, the baits, along with surrounding soil, were recovered with a 16-cm-
diam posthole digger to a depth of about 25 cm. The soil was sieved through two screens (8
and 10 mesh per 2.5 cm), and the wireworms discovered were counted and placed in bottles.
The bottles, along with the baits, were brought back to the laboratory for further
examination, counts and identification of wireworms. Soil below 25 cm (usually as deep as
50-60 cm) was also removed and cursorily examined for wireworms. The total number of
wireworms found at each site included the field counts plus any additional wireworms found
in the baits during laboratory examination. The mean number of wireworms per bait per site
was calculated based on the total number of baits recovered because some baits were not
recoverable. Wireworm species were determined based on keys and descriptions in Glen et
al. (1943) and Wilkinson (1963).
RESULTS AND DISCUSSION
The mean number of wireworms per bait per site varied from O to 4.4 (Table 1). The
wireworm species, number of sites they were found at, and percentage of the total were as
follows:
Species No. sites %
Ctenicera pruinina (Horn) 16 38.6
Melanotus longulus oregonensis (LeConte) 10 19.1
Limonius californicus (Mannerheim) 5 23-5
Limonius infuscatus Motschulsky 2 9.6
Dalopius sp. 1 5.6
Ctenicera glauca (Germar) | $2
Aeolus mellillus (Say) 1 0.4
Umatilla County was represented by three species and had the highest mean number of
wireworms per bait per site (2.23), followed by Union County with 1.19 wireworms,
predominately L. californicus. The wireworms (0.67/bait/site) in Gilliam County were
comprised of a mixture of four species, although only C. pruinina was present in three of the
four sites with wireworms, whereas all of the wireworms (0.40/bait/site) in Morrow County
were C. pruinina. Sherman County had 0.30 wireworms per bait per site (a mixture of four
species), Baker County had 0.31 wireworms (all M. longulus oregonensis), Wasco County
had 0.20 wireworms, and Wallowa and Jefferson Counties had none. No wireworms were
found in soil below the baits.
A baiting technique indicates whether or not wireworms are actively present, and their
relative abundance. It does not, however, give a measure of wireworm density as soil
sampling does. Because no soil samples were taken in this study, the wireworm density at
each site was estimated based on results of Toba and Turner (1983). They found that after 3
wk exposure of baits in June, the ratio of wireworms per bait: wireworms per 929 cm? (1 ft2)
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 oe |
of soil sample was 0.59:1, Although climate and soil type were similar in both studies, we
considered that room for error existed in using their data because of differences in time of
study (June vs. July and August), location, and other factors. However, no other published
reports could be found regarding the relationship between bait and soil sample, and soil
temperatures recorded at our study sites (mean of 20.9°C) corresponded to that for June
(22°C) in Toba and Turner’s study. Thus, after calculating the estimated number of
wireworms/929 cm? of soil at each site (Table 1), the highest density was found at location
28E,3N,24 with 7.45 wireworms.
Information is also lacking on damaging threshold populations of wireworms in wheat.
However, Toba et al. (1985) have presented data that may be helpful in providing such
information. When winter wheat was planted in plots treated with 4.5 kg a.i./ha fonofos and
incorporated 10-15 cm deep, to provide the best possible treatment as an indication of
potential yield in the absence of wireworms, yields in treated plots did not differ from those
in untreated control plots even when the population density was as high as 6.87 wire-
worms/929 cm2 of soil. With spring wheat, a density as low as 4.84 wireworms/929 cm2
was capable of significantly reducing yields in the control plots compared to the fonofos-
treated plots. Similar results were obtained by Toba et al. (1988) in which spring wheat yields
in plots of untreated seeds were significantly lower than those in plots having seeds treated
with carbosulfan, lindane or fonofos. In the present study, only one site had more than 6.87
wireworms/929 cm? (Table 1), but it would be questionable whether even this density would
cause a yield reduction in winter wheat. However, there were three sites with densities
greater than 4.84 wireworms/929 cm. Therefore, it appears that damaging populations can
be found in wheat-growing areas of northcentral and northeastern Oregon, at least to spring
wheat.
False wireworms, the larvae of certain genera of Tenebrionidae, are also important
because they cause damage similar to that of wireworms in wheat crops (Calkins and Kirk
1975). We found false wireworms, primarily Eleodus, as follows:
Site location (County) No./site
28E,3N,33a (Umatilla) 1]
20E,2N,32 (Gilliam) 10
26E,1N,20 (Morrow) 7
27E,3N,25 (Umatilla) 5
16E,8S,28 (Wasco) 3
28E,3N,33b (Umatilla); 17E,3S,7 (Sherman); 21E,1N,24 (Gilliam) 2
13E,1S,9 (Wasco); 17E,7S,27 (Wasco) ]
When they were included in calculations for estimating density of wireworms and false
wireworms per 929 cm? of soil, they did not add materially to the density of wireworms
shown in Table 1; i.e., no additional sites had densities higher than 4.48 larvae/929 cm?.
However, no information is available on the attractancy of false wireworms to the bait we
used or on the relationship between the number found at baits and the density per 929 cm? of
soil.
Despite the apparent lack of damaging populations; it is possible that our estimates were
conservative. Toba and Turner (1983) showed that the number of wireworms found at baits
decreased from April to June, which in all likelihood was directly related to decrease in soil
moisture. Because our study was conducted in July and August, one would expect soil
moisture, and consequently the number of wireworms at the baits, to be lower than they
would have been in June.
There appears to be no correlation between wireworm density and ranchers’ practice of
using seeds treated for wireworm control. Even if a damaging population was found in a field
where treated seeds had been in use, one would expect such a treatment to exert pressure on
the population, thereby preventing the development of an even higher population. On the
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
28
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other hand, lack of damaging populations in fields where no treated seeds had been in use is
no assurance that damaging populations will not develop in the future.
Our results, along with those of Toba and Turner (1983) and Toba et al. (1985, 1988),
indicated that the population densities of wireworms found in the wheat-growing areas
studied apparently were not high enough to cause yield reduction in winter wheat, although
they could cause stand reduction. The reason for this is that yield may not be affected despite
a 20% reduction in plant stand (Harwood et al. 1957), whereby stand reduction is
compensated by increased tillering by the remaining plants. On the other hand, population
densities do exist that can reduce yields in spring wheat.
ACKNOWLEDGMENTS
We thank George Amoah and Clifton Tucker for their assistance, and special thanks to Earl
Perkins for his technical assistance. We are also grateful to Harry G. Davis (USDA-ARS,
Yakima, Wash.) and Keith S. Pike (Wash. St. Univ., Prosser, Wash.) for reviewing the
manuscript. This study was funded primarily by the Oregon Wheat Commission.
REFERENCES CITED
Calkins, C. O. and V. M. Kirk. 1975. False wireworms of economic importance in South Dakota. Monograph,
Northern Grain Insects Res. Lab. USDA, ARS, and South Dakota St. Univ. B633, 38 p.
Glen, R., K. M. King and A. P. Arnason. 1943. The identification of wireworms of economic importance in
Canada. Can. J. Res. 21: 358-387.
Harwood, R. F, W. L. Nelson and H. S. Telford. 1957. Seed treatments of wheat for control of the Great Basin
wireworm. J. Econ. Entomol. 50: 702-703.
Hyslop, J. A. 1915. Wireworms attacking cereal and forage crops. USDA Bull. No. 156, 34 p.
Jones, E. W. and F H. Shirck. 1942. The seasonal vertical distribution of wireworms in the soil in relation to their
control in the Pacific Northwest. J. Agr. Res. 65: 125-142.
Lane, M. C. 1935. Récent progress in the control of wireworms. Jn Proc. World’s Grain Exhibition and Conf. (1933)
2: 529-534. Ottawa: Can. Soc. Tech. Agriculturists.
Onsager, J. A. 1969. Sampling to detect economic infestations of Limonius spp. J. Econ. Entomol. 62: 183-189.
Toba, H. H. and J. E. Turner. 1983. Evaluation of baiting techniques for sampling wireworm (Coleoptera:
Elateridae) infesting wheat in Washington. J. Econ. Entomol. 76: 850-855.
Toba, H. H., L. E. O’Keeffe, K. S. Pike, E. A. Perkins and J. C. Miller. 1985. Lindane seed treatment for control of
wireworms (Coleoptera: Elateridae) on wheat in the Pacific Northwest. Crop Prot. 4: 372-380.
Toba, H. H., K. S. Pike and L. E. O’Keeffe. 1988. Carbosulfan, fonofos, and lindane wheat seed treatments for
control of sugarbeet wireworm. J. Agric. Entomol. 5: 35-43.
Ward, R. H. and A. J. Keaster. 1977. Wireworm baiting: use of solar energy to enhance early detection of Melanotus
depressus, M. verberans, and Aeolus mellillus in Midwest cornfields. J. Econ. Entomol. 70: 403-406.
Wilkinson, A. T. 1963. Wireworms of cultivated land in British Columbia. Proc. Entomol. Soc. Brit. Columbia 60:
3-17.
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 3]
Biology of the black vine weevil Otiorhynchus sulcatus
on hop in Idaho (Coleoptera: Curculionidae)!
CRAIG R. BAIRD2, KEITH W. DORSCHNER AND CAROLYN J. NYBERG
1 Scientific Paper Number 91784, University of Idaho Agricultural Experiment Station
2 University of Idaho, Parma Research and Extension Center, 29603 U of I Lane, Parma, Idaho 83660
ABSTRACT
The black vine weevil, Otiorhynchus sulcatus (Fabricius), is an important pest of hop,
Humulus lupulus L., in Idaho. Although some adults survived winter conditions, O. sulcatus
overwintered primarily as developing larvae associated with hop root systems 5-50 cm deep
in the soil. Primary damage occurred as nearly mature larvae girdled small roots and
rhizomes during spring feeding. Pupation began in mid-April with soil temperatures of
15-17°C and concluded in mid- to late May. Adult emergence began in early May and was
complete by late May to early June during 1986-1988. The preoviposition period averaged 26
days in the field. The mean number of eggs laid per adult female was 290 (22-1230). Eggs
hatched in 12-22 days at 21°C.
INTRODUCTION
The black vine weevil, Otiorhynchus sulcatus (Fabricius), is an important pest of commer-
cially grown hop (Humulus lupulus L.) in the Pacific Northwest. Nearly 1000 acres of
infested hop have been removed from production in Idaho within the last 10 years because of
this pest. Selective replanting of infested areas has enabled some yards to remain productive
for several additional years. In Washington, O. sulcatus is also an important hop pest (Mayer
and Cone 1985), although damage is not as extensive as in Idaho.
Nearly 200 plant species are listed as hosts of O. sulcatus (Smith 1927, Essig 1933,
Warner and Negley 1976 and Masaki et al. 1984), yet this is the first published record of hop
being infested at economically important levels in the United States. The biology of O.
sulcatus on this perennial plant is poorly understood and no information is available in the
literature on this host-pest relationship.
There are no natural agents effecting significant control in Idaho hop yards. Efforts have
been directed at controlling adult weevils with foliar sprays after emergence but before
Oviposition (Baird and Nyberg 1987). More recently, several nematode parasites have
demonstrated control in the field (Dorschner et al. 1989). This paper reports on a multi-year
study of the biology of black vine weevil on hop in Idaho.
METHODS AND MATERIALS
Root weevil adults and larvae were collected in soil samples from hop yards in the Notus,
Wilder and Greenleaf areas about 35 mi (55 km) W of Boise, near the Oregon border in
Canyon County (Elev = 700 m), Idaho between 1977 and 1989. Larvae were reared to adults
in 100 < 15 mm petri dishes containing slightly moistened soil. Adult identifications were
confirmed by W.E Barr, University of Idaho, and D.H. Whitehead, United States National
Museum. Voucher specimens are deposited at each location.
Soil sampling consisted of removing soil from around hop roots and crowns to a depth of
18-50 cm, screening the soil through 4 mesh/cm metal screen, removing root weevil life
stages, and replacing the soil around the hop root system. To determine developmental
events in field populations, soil sampling was completed semi-weekly from March through
September in infested hop yards (N = 50 BVW specimens). Soil temperatures were
recorded at 10 cm depth at time of sampling, usually between 1000 and 1400 hr. Soil type was
sandy with pH 7.5.
Internal egg development was monitored by dissecting newly emerged adults (20 per
week) and examining them for reproductive tract condition and egg development. When
newly emerged adults indicated egg maturity, close observations were begun on adult
32 J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
weevils in the field to observe oviposition behavior, sites and timing. Egg production was
determined by placing newly emerged adults in petri dishes with slightly moistened filter
paper and a new hop leaf daily for food (Penman & Scott 1976). Adults in petri dishes were
maintained in shade at outdoor temperature and photoperiod.
To determine the sequence of developmental changes through the pupal stage, 100 mature
larvae were collected in early March and placed in individual plastic cups (3 X 3 X 3 cm)
filled with soil from the collection site. Sufficient moisture was provided to prevent
desiccation. Cups were maintained at outdoor temperature (12—16°C) and photoperiod by
placing them in shaded areas protected from severe weather. Specimens were observed daily
while larvae, then twice daily after pupation. As rapid changes in pupal development
occurred, hourly observations were made. Teneral adults were observed twice daily during
the tanning period (17—19°C).
To determine the ability of adults to overwinter, 250 adults were placed in screened cages
(91 X 61 X 61 cm) filled with soil and young, cutback hop plants. The cages were maintained
outdoors under field conditions from September to April. Evaluations were then made by
carefully screening the soil and counting the living adult weevils in each cage.
Mean Soil Temp. 10 cm Depth, °C.
% Population
ol
i)
O-6
March
ae o ~ S = SS
i, —,
Figure 1. Percent larvae, pupae, adult black vine weevil and mean soil temperature in semi-weekly soil
samples (1986).
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 33
RESULTS
Species of root weevils present. Soil and plant debris sampling of 36 hop yards in Canyon
County, Idaho revealed low infestation levels overall. Certain varieties, i.e. Cascade and
L-8, had high root weevil numbers in at least some portion of the yard whereas most other
varieties were lightly-infested. Black vine weevil, O. sulcatus, was the dominant species
found (94.2 %) with strawberry root weevil, O. ovatus, (4.8%), rough strawberry root
weevil, O. rugosostriatus, (0.8%), and O. meridionalis (0.2%) occurring at lower levels.
Two hop yards, var L-8 and Cascade, had O. ovatus as the dominant species (83%) and O.
sulcatus (17%) during initial investigations during 1978, but the percentage reversed within
two years and O. sulcatus remained the dominant species. No males of any Otiorhynchus
species were found while examining over 1500 specimens.
General life history. Root weevils overwintered in the soil primarily in the larval stages,
although a small percentage of adults also survived the winter in the soil. Overwintering
larvae pupated beginning the second week of April, and the earliest adult emergence
occurred in early May (Figs. 1,2,3). In most years, adults emerged by 27-30 May, but late
emergence extended into mid-June. Oviposition by new adults began in late June, peaked by
late July and concluded by early September (Fig. 4). Overwintered adults began oviposition
in late May to early June and concluded by early July.
no NY O W
oa o a
=
=)
Mean Soil Temp. 10 cm Depth, °C.
Oo a on
100
% Population
ol
©
Figure 2. Percent larvae, pupae, adult black vine weevil and mean soil temperature in semi-weekly soil
samples (1987).
34 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
Mean Soil Temp. 10 cm Depth, °C.
% Population
Figure 3. Percent larvae, pupae, adult black vine weevil and mean soil temperature in semi-weekly soil
samples (1988).
PERCENT OF ADULT BVW WITH
DEVELOPING EGGS
100
80 O - - 0 1987
70 m@--°--8 1988
% Population
ol
r=)
March April May July | Aug. | Sept.
Figure 4. Percent of adult black vine weevil with developing eggs (1986-88).
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 35
Larval and adult feeding and damage. Larval feeding extended from late summer into
the following spring with the primary damage being caused by larvae scoring and girdling
3-20 mm diameter hop roots. The most visible damage resulted from late instar feeding in
early to late spring. During the coldest months, larvae were found 30-50 cm deep in the soil
closely associated with the woody hop crown with little damage evident. Within a few hours
after emerging from the soil, adults began feeding intermittently on hop leaves, but the
defoliation was slight (<2%) and has not been demonstrated to be important. Adults were
also observed feeding on several weed species including pigweed and lambsquarter and
ornamental shrubs (lilacs) in the Ada and Canyon County areas.
Table 1
Developmental Changes During Black Vine Weevil Pupal Stage (12—16°C).
Elapsed Time Developmental Events
0.0-1.0 days Mature larva (prepupa). Feeding ceases, thoracic segments swell,
integument splits along dorsal line; Pupa emerges.
1.0-2.0 days Pupa translucent white, spine tips light brown.
4.0-6.0 days Pupa milky white.
8.0-10.0 days Pupa yellowish-white; compound eyes dark red top half, light red bottom
half; antennae bases light brown; tarsal claws tan distally.
10.0-12.0 days Dorsum of head medium brown; femora-tibiae joint medium brown;
compound eye uniformly red; tarsal claws light brown; mandibles visible,
dark brown; antennae bases dark brown.
12.0-13.0 days Dorsum of head dark brown; snout dorsum dark brown; antennae bases
black, other segments light brown; tarsal claws black; mandibles black;
sclerite margins light brown; elytra separated slightly, tan lines visible.
13.0-13.5 days First visible signs of molt, liquid droplets on pupal body. Ecdysis occurs.
Cuticle splits at leg base, peels off distally; antennae cuticle splits at base,
peels off distally; cuticle splits at vertex of head, peels off to snout,
mandibles; elytra folds into position on dorsum; molt complete in 3-6 hr.
Developmental events in field populations. During 1986-88, five to ten percent of the O.
sulcatus field population overwintered as adults in the soil. In separate tests of caged adults
maintained outdoors during these same winters, 11 to 14 percent survived.
In early March, late instar larvae were found in close proximity to hop roots from 2 to 30
cm deep in the soil. Fresh girdling and scoring on roots indicated recent feeding. By mid
March, most larvae were mature and had moved higher in the soil profile away from the root
system. By late March, mature larvae in prepupal cells were found 2-6 cm deep in the soil.
During 1986 through 1988, the earliest pupae were found from 11-21 April reaching a
peak of 62-70% in pupal stage by 15 May. The average pupal period was 18 days, however,
this varied from 15 to 30 days. New, teneral adults were first found 2 May reaching a peak
adult (98-100%) emergence by 27-30 May. Teneral adults were found in soil samples until 7
June (1986-87) and until 21 June in 1988.
Newly emerged adults taken in field samples showed little evidence of internal egg
development until 21-26 June when 30% were gravid (Fig. 4). An increasing prevalence of
gravid females occurred through early July reaching 100% of the weevil population by July
22-29. The earliest egg deposition in field populations was on 20 June 1986 and 24 June
1987. Most adult weevils were gravid and ovipositing by early July and had completed
oviposition by mid August, however, a few eggs were laid in early September. Overwintered
adults, being a very small portion of the population, were difficult to observe. However,
limited observations indicate early onset of oviposition (late May) and completion by early
July. In commercial hop yards, eggs hatched in 14-18 days.
Observations in laboratory populations. The sequence of morphological and color
changes in pupae transforming to adults is described in Table 1. Adult tanning and color
changes following eclosion are described in Table 2.
36 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
Feeding on hop leaves began within 24 hr of adult emergence from the soil. Caged adults
fed readily on hop leaves usually notching the leaves but at times feeding on the inner leaf
portions thus skeletonizing the leaf. As in the field observations, all feeding was at night.
The preoviposition period (eclosion to oviposition) averaged 26 days (14-75 days) for
adults from field populations. Maximum egg production occurred in weevils with a
preoviposition period of 17-23 days and dropped off sharply after 25 days. Weevils with
onset of oviposition delayed beyond 30 days had very low egg counts.
Table 2
Tanning Sequence of Teneral Adult Black Vine Weevils (17-19°C).
Elapsed time Developmental events
0-10 hr Newly emerged adult; antennae and snout dorsum light brown; distal
femora, proximal tibiae light brown; dorsal thorax, ventral snout, sternites
light tan; mandibles and antennae bases black.
16—24 hr Distal femora and proximal tibiae dark brown; remainder of legs light
brown; snout dorsum anterior 7/3 black; elytra tan.
2—4 days Distal femora and proximal tibiae black; snout dorsum anterior */4 black;
snout venter anterior !/2 black; coxae light brown.
4-8 days Ventral and dorsal head and snout black; legs except coxae black; coxae
reddish brown; elytra and thorax dorsum dark brown; thorax venter reddish
brown.
8—10 days Thoracic sternites dark brown; coxae dark brown; other head, thorax,
abdomen areas black; yellow tufts visible on elytra.
10-21 days All areas black except for yellow tufts on elytra.
During oviposition, the female lowered the terminal abdominal segment and extended
the ovipositor about 1.5 mm. Individual eggs were then forced down the egg tube and
deposited singly or in small, unevenly spaced groups. They were laid on the soil surface, in
soil crevices, and on leaves. The mean number of eggs laid per day per ovipositing adult was
10 with a maximum of 45 (20—21°C). The mean oviposition period for 113 weevils was 33
days with oviposition being frequently interrupted by feeding intervals of 2-6 days. The
average number of eggs laid by a single adult in one season was 290 (22-1230). Eggs laid
under laboratory conditions hatched in 12-22 days (21°C).
DISCUSSION
Black vine weevil (O. sulcatus) was the most common root weevil species found in Idaho hop
yards, although strawberry root weevil (O. ovatus) was found in dominant numbers in two
yards and occasionally in other yards throughout the study. Otiorhynchus rugosostriatus and
O. meridionalis were rare in collections from hop yards but were occasionally collected from
ornamental hosts in the area. Essig (1933) reported O. sulcatus as a hop pest in Great Britain
but not in the United States. He further indicated O. sulcatus is the most widely distributed
Otiorhynchus species in North America but did not list hop among its host plants. Warner
and Negley (1976) listed O. ovatus from hop in the United States but did not record O.
sulcatus and O. rugosostriatus on hop as we found in this study. Cone (Pers. Comm. 1991)
indicated O. sulcatus is a significant pest in Washington hop yards.
Based on specimens in museums (University of Idaho, Moscow and Albertson College of
Idaho, Caldwell), the next most frequent collection site for O. sulcatus in Idaho is lilac and
for O. ovatus, caneberries and as a transient pest in homes and yards. Interestingly, O. ovatus
is rare in commercial peppermint in Idaho, even in fields adjacent to infested hop yards, yet it
is an important pest of mint (Mentha spp.) in Oregon.
Black vine weevil not only has a wide host range but has-adapted to widely differing
conditions in the Pacific Northwest and elsewhere. Adult emergence in Idaho hop yards
began earlier (2 May) than in western Washington strawberries (31 May) (Garth and Shanks
1978) or south central Washington grapes (17 June) (Cone 1963).
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 37,
There was considerable variation in the preoviposition period observed in various
locations and host plants. According to most authors, O. sulcatus oviposition is dependent
upon the food source and quality resulting in a shorter preoviposition period and more eggs
when adults fed on optimal host plant tissue (Cram and Pearson 1965). Shanks and Finnigan
(1973) stated the preoviposition period for O. sulcatus on strawberries in western Washing-
ton to be 3-4 weeks. Garth and Shanks (1978) found the interval to be 7 weeks during a
cooler than average season. Ambient temperature and water availability (plant succulence)
also affect the length of the preoviposition period and egg production (Cram 1970, Shanks
1980). Our findings of 3-4 weeks on Idaho hop are within the range reported by other
workers. The number of eggs laid per day and per season on hop was highly variable but
within the range found on other crops (Cram 1970, 1980, Shanks 1980, Doss and Shanks,
1985).
Egg development time at 12-22 days was quite variable whether in the laboratory or under
field conditions but was within the range reported by other workers (Smith 1927).
Changes in O. sulcatus pupae and teneral adults during the developmental processes have
not been described by other workers. Although there was variation among the 200 weevils
observed, the elapsed times recorded in Tables | and 2 represent the timing of most of the
individuals observed and provide a reference for determining age and stage of development
for future researchers.
ACKNOWLEDGEMENTS
We wish to thank the Idaho Hop Commission, the Hop Research Council, Busch Agri-
cultural Resources Inc. and Miller Brewing Company for partial funding of this project. We
also thank Dr. Guy Bishop, University of Idaho and Mr. Dan Dixon, Greenleaf, Idaho for
providing assistance, equipment, and suggestions during this study. We also acknowledge
the assistance of Drs. Carl Shanks, Jr., Washington State University, and Robert L. Stoltz,
University of Idaho who reviewed the manuscript and provided helpful suggestions.
LITERATURE CITED
Baird, C.R. and C.J. Nyberg. 1987. Control of root weevils on hops with foliar sprays, 1985 and 1986. Ins. & Acar.
Tests 12:258.
Cone, W.W. 1963. The blackvine weevil, Brachyrhinus sulcatus as a pest of grapes in south central Washington. J.
Econ. Entomol. 56:677-80.
Cram, W.T. 1970. Acceptability of cultivars of highbush blueberry at varying temperatures by adult black vine
weevils (Col.:Curculionidae). J. Entomol. Soc. Brit. Columbia 67:6-7.
. 1980. Fecundity of the black vine weevil, Otiorhynchus sulcatus (Coleoptera:Curculionidae), fed foliage
from some current cultivars and advanced selections of strawberry in British Columbia. J. Entomol. Soc. Brit.
Columbia 77:25-26.
Cram, W.T. and W.D. Pearson. 1965. Fecundity of the black vine weevil, Brachyrhinus sulcatus, fed on foliage of
blueberry, cranberry, and weeds from peat bogs. Proc. Entomol. Soc. Brit. Columbia 62:25-27.
Dorschner, K.W., EF Agudelo-Silva, and C.R. Baird. 1989. Use of heterohabditid and steinernematid nematodes to
control black vine weevils in hop. Florida Entomol. 72:554-556.
Doss, R.P. and C.H. Shanks, Jr. 1985. Effect of age on the feeding pattern of the adult black vine weevil,
Otiorhynchus sulcatus (Coleoptera:curculionidae). Ann. Entomol. Soc. Amer. 79:322-325.
Essig, E. O. 1933. The economic importance of the genus Brachyrhinus (Otiorhynchus). Monthly Bull. Calif. State
Dept of Agr. 22: 397-409.
Garth, G.S. and C.H. Shanks, Jr. 1978. Some factors affecting infestation of strawberry fields by the black vine
weevil in western Washington. J. Econ. Entomol. 71:443-8.
Masaki, M., K. Ohmura, and F Ichinohe. 1984. Host range studies of the black vine weevil, Otiorhynchus sulcatus,
(Fabricius) (Coleoptera:Curculionidae). Appl. Ent. Zool. 19:95-106.
Mayer, D.E and W. W. Cone. 1985. Insect pests of hop. Jn: Hop production in the Yakima Valley. Extension Bulletin
1328. Cooperative Extension Service, Washington State University, Pullman.
Penman, D.R. and R.R. Scott. 1976. Adult emergence and egg production of the black vine weevil in Canterbury.
N. Z. J. Exp. Agric. 4:385-9
Shanks, C.H., Jr. 1980. Strawberry and yew as hosts of adult black vine weevil and effects on oviposition and
development of progeny. Environ. Entomol. 9:530-531.
Shanks, C.H., Jr. and B.F Finnigan. 1973. Temperature and relative humidity effects on eggs and first-stage larvae
of the black vine weevil, Otiorhynchus sulcatus. Environ. Entomol 2:855-8.
Smith, EF 1927. The black vine weevil (Brachyrhinus sulcatus Fabr.) as a pest in greenhouses and nurseries. J.
Econ. Entomol. 20:127-31.
Warner, R.E. and EB. Negley, 1976. The genus Otiorhynchus in America north of Mexico (Coleoptera:
Curculionidae). Proc. Entomol. Soc. Wash.78:240-62.
38 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
The distribution and life cycle of Reduvius personatus (L.)
(Hemiptera: Reduviidae) in Canada
G.G.E. SCUDDER
DEPARTMENT OF ZOOLOGY, UNIVERSITY OF BRITISH COLUMBIA
VANCOUVER, B.C. V6T 1Z4
ABSTRACT
The distribution of Reduvius personatus in Canada is mapped, and is recorded for the first
time from New Brunswick. It is shown that this species has a two-year life cycle in this
country, overwintering as larvae in both the third and fifth instars. Most adult emergence
occurs from May to early October, with a peak in June-July.
INTRODUCTION
Reduvius personatus (L.) known popularly as the “kissing bug”’, the “masked bug” or the
‘masked bed-bug hunter”, is a cosmopolitan species that occurs widely in North America,
ranging from Quebec and New England west to Kansas and south to Florida (Blatchley 1926;
Slater and Baranowski 1978; Froeschner 1988). In Canada it has been recorded from Ontario
and Quebec in the east and British Columbia in the west (Moore 1950; Larochelle 1984;
Scudder 1961; Froeschner 1988).
Both adults and immatures cover themselves with lint and dirt (Blatchley 1926; Harz
1952; Immel 1954), and hide in corners and crevices waiting for prey, which usually consists
of flies and other soft-bodied insects such as silverfish, booklice, bedbugs and harvestmen
(Harz 1952). Leconte (1855) reports that R. personatus can bite humans, and that the pain
caused is almost equal to that of a snake bite, the swelling and irritation sometimes lasting
for a week.
Reduvius personatus 1s reported as typically having one generation a year and overwinter-
ing as a fourth or fifth instar larva in England, Germany and the Ukraine (Puchkov 1986).
However, Puchkov (1986) notes that in the USA and Germany, cases are known where the
life cycle lasts two years, and larvae spend the first winter in the third instar. Readio (1931)
found that larvae that pass the first winter in the third instar take two years for development,
entering diapause again in the fifth instar and passing the second winter in that stadium.
This paper reports on the occurrence of a two year life cycle in Canada, and summarizes
the distribution and phenology in this country.
MATERIAL AND METHODS
Previous published records were summarized and specimens in the Canadian National
Collection, and various other collections across Canada were studied to document the
distribution. Seasonal occurrence of adults was determined from specimen labels and
graphed according to the methods of Sods (1958).
Evidence for a two year life cycle in British Columbia was obtained by recording the
occurrence of immature stages at Osoyoos in October 1989, and in April and October 1990.
Evidence for a two year life cycle in Ontario was obtained by rearing a specimen through two
years.
On March 1, 1988, while I was working on the Canadian National Collection in Ottawa, a
Mr. Vernon Alexander brought: in a live third instar larva of R. personatus collected in a
house in that city. This specimen was brought to Vancouver and reared. The larva was kept
in a small plastic container in my home and fed various insects, mostly Diptera. For the most
part these were adult Syrphidae, Calliphora spp., and Pollenia rudis (Fabr.). Fresh food was
presented once every week. Occasionally adult clay-coloured weevils (Brachyrhinus singu-
laris (L.)) were offered as food, but these were rarely accepted. Third instar locusts
(Schistocerca gregaria Forskal) were offered during cold spells in winter when no other
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 39
insects were readily available but no feeding was observed. Temperature was maintained
between 18.5°C (0700-2300 H) and 16.5°C (2300-0700 H) in winter, but at times was as high
as 26.5°C in the summer during the day. The larva of R. personatus was examined for
evidence of molting, when the food was changed each week.
RESULTS AND DISCUSSION
A total of 186 specimens of adults of R. personatus from British Columbia, Ontario and
Quebec were examined. Place and dates of capture were recorded. Figure | records the
distribution of the species in Canada, based on the museum specimens studied, and
previously published records. The species here is recorded from New Brunswick for the first
time (Fredericton, 30 June 1933 (C.E. Atwood)) [Royal Ontario Museum]. It is clearly
restricted to the southern areas of the country.
Both adults and larvae of R. personatus typically live in houses and outhouses (Blatchley
1926; Southwood and Leston 1959), and in British Columbia have been recorded as
abundant in dockside warehouses in Vancouver (Scudder 1961), and inside and outside
houses and garden sheds in Osoyoos (Scudder, unpublished). In spite of living in such a
habitat, R. personatus is not so widely distributed as some other insects that live in homes in
Canada. For example, Vickery and Kevan (1986) document that the cosmopolitan American
cockroach (Periplaneta americana (L.)) occurs in buildings from British Columbia to
Newfoundland, and the cosmopolitan German cockroach (Blattella germanica (L.)) which
occurs in stores, warehouses, bakeries, food-processing and storage buildings and dwell-
ings, occurs in Alaska, Yukon, Northern Quebec and across the southern half of Canada.
Southwood and Leston (1959) found that R. personatus was restricted to the southern part of
the British Isles, occurring north only to Lancashire, but being absent from Ireland,
Scotland and Wales.
Figure 2 diagrams the frequency of occurrence of adult R. personatus collected in
Canada. Most emergence occurs from May to early October, with a peak in June-July. The
time of occurrence of adults in Canada, is thus similar to that in the USA. Blatchley (1926)
reports their occurrence from June 11 to July 9 in Indiana, and August 15 in Alabama, and
Readio (1931) records that adults occur from May to September at Lawrence, Kansas. The
time of occurrence of adults of R. personatus in the southern Ukraine is also similar to that in
North America (Puchkov 1986).
Most records of insects attracted to light are in June and July in both British Columbia and
Ontario. Similarly, Blatchley (1926) reported that in Indiana, adults are most common flying
to light at dusk in June.
A total of two second instar, five third instar, eight fourth and three fifth instar larvae of R.
personatus were captured at Osoyoos in October 1989 and 1990. These data suggest that in
this locality the species overwinters for two years as reported in the USA by Readio (1931):
the first winter is spent in the third instar and the second as a fifth instar. This was confirmed
by the capture of only third and fifth instar larvae at Osoyoos in April 1990.
Rearing of the single larva captured as a third instar in Ottawa during March 1988
confirms this two-year life cycle in Ontario. This insect reached the fifth instar in October
1989, overwintered in this stage, and emerged as an adult on May 15, 1989. It did not feed
during the winter, although food was always available and temperature was maintained
between 16.5°C and 18.5°C. Unlike many other insects with long life cycles (Danks 1992),
dormancy in R. personatus is evidently inherent and not induced by environmental
temperature or humidity (Readio 1931).
It would seem that the life cycle of R. personatus in Canada is similar to that reported for
this species in the USA and Germany, where two-year life cycles are recorded (Readio 1931;
Puchkov 1986). Whether or not this species in North America also has populations with a
single generation a year as in England, Germany and the Ukraine (Puchkov 1986) is still
unknown. It will be necessary to undertake many more rearing experiments before this is
clarified.
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
40
Distribution of Reduvius personatus in Canada.
Figure 1.
4]
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
daa Nn
MONTH
Figure 2. Frequency of adult Reduvius personatus occurrence throughout year in Canada.
42 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
ACKNOWLEDGMENTS
Research on the collections across Canada was supported by a grant from the Natural
Sciences and Engineering Research Council of Canada. I am indebted to S.A. Marshall
(University of Guelph), PM. Sanborne (Lyman Entomological Museum, McGill Univer-
sity) and G.B. Wiggins (Royal Ontario Museum) for information. R. Trottier kindly
permitted me to spend an extended period studying the Canadian National Collection at
Agriculture Canada in Ottawa.
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Indiana and Florida. Nature Publishing Co., Indianapolis.
Danks, H.V. 1992. Long life cycles in insects. Can. Ent. 124: 167-187.
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R.C. Froeschner (Eds. ) Catalog of the Heteroptera, or True Bugs, of Canada and the Continental United States.
E.J. Brill, Leiden, New York, Kobenhavn, Koln.
Harz, K. 1952. Ein Beitrag zur Biologie von Reduvius personatus L. (Rhynchota Heteroptera) NachrBl. bayer. Ent.,
Munich |: 73-75.
Immel, R. 1954. Biologische Bebobachtungen an der Staubwanze (Reduvius personatus L.) Zool. Anz. Leipzig
152: 96-98.
Larochelle, A. 1984. Les Punaises Terrestres (Hemipteres: Geocorises) du Quebec. Fabrevies, Suppl. 3: 1-513.
Leconte, J.L. 1855. Remarks on two species of American Cimex. Proc. Acad. Nat. Sci. Philadelphia 7: 404.
Moore, G.A. 1950. Check-list of Hemiptera of the Province of Quebec. Contr. Inst. Biol. Univ. Montreal 26: 49 pp.
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Slater, J.A., and R.M. Baranowski. 1978. How to know the true bugs (Hemiptera-Heteroptera). Wm. C. Brown Co.,
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wendbarr. Acta Ent. Mus. Nat. Prague 32: 101-150.
Southwood, T.R.E., and D. Leston. 1959. Land and water bugs of the British Isles. Frederick Warne & Co. Ltd.,
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Vickery, V.R., and D.K. McE. Kevan. 1986. The Grasshoppers, Crickets, and Related Insects of Canada and
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The Insects and Arachnids of Canada Part 14. Research Branch Agriculture Canada Publ. 1777: 918 pp.
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 43
A life stage development index for
Trypodendron lineatum (Oliv.) in a spruce boom on
the Alberni Canal, Vancouver Island
R.L. MCINTOSH AND J.A. MCLEAN
DEPARTMENT OF FOREST SCIENCES
FACULTY OF FORESTRY
THE UNIVERSITY OF BRITISH COLUMBIA
270-2357 MAIN MALL,
VANCOUVER, B.C. V6T 1Z4
ABSTRACT
Development of 7rypodendron lineatum Oliv. was monitored in a high-grade log boom of
Sitka spruce, Picea sitchensis, stored in the Alberni Canal, B.C. in 1991. Twenty-eight logs
were surveyed at weekly intervals from April 19 to September 13, 1991. By the sixth week all
28 logs had been attacked. Every week, chunks of wood were cut from each attacked log and
total of all life stages were recorded. Changes in insect development and the presence or
absence of stain were noted. The ratio of brood adults to parental adults was 10:1 and it was
determined that the timing of both parental and brood adult emergence coincided in the
“sister” flight. An insect development profile was constructed from these data, and an index
was produced for estimating the minimum number of days required to reach specific stages
in development. When combined with logging and transportation information, the index
provided an estimate of where and when the logs had been attacked. With this information,
modifications in management strategies can be réviewed and steps taken to avoid pest
populations being transported to storage areas.
Key words: Trypodendron lineatum, ambrosia beetle, life stages, stain, insect develop-
ment index.
INTRODUCTION
The ambrosia beetle, Trypodendron lineatum (Olivier.), 1s a serious pest to the forest
industry and has caused extensive degrade to high-grade logs in coastal British Columbia
(Kinghorn and Chapman 1959; Dyer 1963; Gray and Borden 1985; McLean 1985). The clear
outer part of the log is the preferred habitat for shelter and brood production of the ambrosia
beetle (Shore 1985; Borden 1988). Degrade results when the valuable outer portion of these
logs has darkly stained pinholes as a result of ambrosia beetle activity. The lumber is
downgraded or rejected from specific markets.
In mid-April ambrosia beetles fly from their overwintering sites in the duff on the forest
floor. Host volatiles arrest the emerging beetles at felled or stored log inventories where they
colonize the sapwood (Borden 1988). Once the wood has been penetrated by the beetles it
becomes stained by the action of symbiotic dark staining fungi. The larvae and parental
adults feed on the ambrosia fungus while the brood develops. The adult beetles tend the
brood inside the log by keeping the galleries clear of frass and by cropping the growth of the
fungus in the galleries. In late summer, after a short maturation period, parental and brood
adults leave the logs and fly to the forest margin to overwinter.
Considerable efforts have been invested in the development of control strategies involving
insecticides (Richmond 1969), trapping studies using pheromones (McLean and Borden
1975; Shore and McLean 1984, 1985; Lindgren 1990) and other methods of integrated pest
management (Richmond and Nijholt 1972; Nijholt 1978; Borden 1988; McLean and
Stokkink 1988). In spite of this knowledge, logs are still being attacked in the forest and
insects are being spread extensively throughout the transportation system (McLean 1991).
In coastal B.C., log inventories accumulate in booming grounds and storage areas prior
to processing. In some cases, depending on supply and demand of certain sorts, this wood
can remain in storage for a considerable length of time. If infested logs are left in storage
areas and sorting grounds at the time of brood emergence in summer, they become the
44 J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
source of the following season’s spring attack flight beetles. Teneral adults will emerge, and
overwinter in adjacent forested margins.
As early as 1950, Graham et al. (1950) researched the use of indices to measure and
assess the degrade caused by ambrosia beetles. The issues of breeding sites and population
estimates were explored by Chapman (1974) and Von Popo and Thalenhorst (1974). There is
a need to know where and when ambrosia beetles attack high value logs. Identification of
high hazard areas can assist in the development of strategies to direct log inventory flow. Log
inventory control can be implemented in the forest, in the sorting areas and the log storage
areas in order to reduce the chances of ambrosia beetle attack on high value saw logs.
Studies were carried out in the Alberni Canal on Vancouver Island to develop a method
where life stages could be used as indicators to estimate the timing of the original attack ona
log. There were two main objectives: first to observe the life stage development of
Trypodendron lineatum over time and to identify key changes in insect development and
conditions in attacked logs; and second to prepare a life stage development index to estimate
where and when the attacks occurred.
METHODS AND MATERIALS
On April 3 1991, sawlogs of Sitka spruce, Picea sitchensis (Bong.) Carr., were transported
by barge from the west coast of Vancouver Island into the Alberni Canal. Timber marks and
inventory information indicated that the logs had been cut between February and March
1991. These logs were sorted in the Alberni Canal. Both bundles and large loose logs were
put into the boom. After the boom was completed on April 18 1991, it was towed out for
storage along the shore of the Alberni Canal, some 2 km south of Port Alberni.
The first survey of the boom was conducted on April 19, at which time all of the non-
submerged logs were surveyed. A total of 28 logs were tallied and numbered for further
survey. Between April 19 and September 13 1991, each of the 28 logs were searched at
weekly intervals for signs of infestation as indicated by the presence of white boring dust
initially and later, entry holes. Most logs were sampled each week as long as the galleries
were accessible. If a log had been attacked, a chunk of wood containing the entrance hole to a
gallery was chopped from the log. The chunk measured approximately 20 cm. square, and
was cut as deep as the insects had penetrated.
TABLE 1
Insect Development Index for 7rypodendron lineatum constructed from data generated during a 22
week survey of a spruce boom in the Alberni Canal from April 19 to September 13, 1991.
Estimated time since
Life stages and visible symptoms attack (days)
Adults only present (no niches) 0-10
Adults; evidence of gallery construction
(egg niches present; some light staining) 11-20
Adults and eggs; niches present
(some dark staining) 21-28
Adults, eggs and early instar larvae |
(wood darkly stained) 29-35
Adults, eggs, late instar larvae and pupae 36-48
Adults, eggs, larvae, pupae and teneral adults 49-84
Adults larvae, pupae, teneral adults present;
empty pupal niches 85-105
Attacked, stained with empty pupal niches
and no life stages >105 days
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 45
PARENTAL ADULTS n=307
LARVAE. n=817 : 20%
a eee TENERAL ADULTS n=533
EMPTY PUPAL NICHES n=2155
19 29 9 16 23 30 6 13 20 26 5 11 18 25 1 9 15 22 29 5 13
APR MAY JUNE JULY AUG SEPT
Figure 1. Kite diagrams to show the relative abundance of the life stages of the ambrosia beetle
Trypodendron lineatum (Oliv.) over time in a log boom of Sitka spruce, Picea sitchensis, in the Alberni
Canal, during the summer of 1991.
46 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
The chunk of wood was then carefully dissected with a pocket knife to expose all insect
life stages. Counts of all parental adults, eggs, larvae, pupae and teneral adults were recorded
as well as the sex of parental adult(s), depth of penetration, presence of niches, and presence
and development of stain.
The total numbers of each of the life stages found at every time interval were summed.
From this information, an insect development profile was constructed to trace the number of
each life stage present in the logs over time. Since there was so much variability in attacks
both within and between logs and because the survey required destructive sampling, this
information was best represented in a “kite” chart to show the relative abundance of each life
stage over time.
RESULTS AND DISCUSSION
The development profile for each life stage in time and the overlap between life stages is
shown in Figure |. It is particularly interesting to note that the number of parental adults
present in the galleries declined at about the same time the teneral adults reach their peak.
The ratio of teneral to parental adults was calculated as 10:1. The decline in the number of
teneral adults from July 5-18 corresponded with the first empty pupal niches. This indicated
that the teneral adults were leaving the niches but were still active in the galleries. Finally, the
parental and teneral adults left the logs at about the same time around the middle of July.
The profiles were then used to construct the life stage development index. The premise of
this index is that all time increments are minimum estimates. The estimated time since
attack represents the minimum time leading to the presence of substantial numbers of each
specific life stage or other gallery phenomena.
For the first 10 days of the survey only adults were present. Activity at this time suggests
that the adults had located a potentially suitable habitat and had initiated “aggregation”. At
the time of the first survey, the mean penetration by adults was 8.4 mm. which, from our
observations suggested that the attack was no more than two days old. The initial attack date
was April 18, 1991. In this establishment phase, there was a period of at least ten days when
only adults were present before any signs of niches or staining were found. This was the first
of the components of the insect development index (Table 1).
Between the first and second surveys, the attacking insects had mated and begun to
excavate the galleries. At this time there were no lateral galleries found. By the time of the
second survey, 70% of the beetles were paired. In all cases, the female was at the head of the
gallery while the male was actively clearing boring dust from the gallery. Many of the
females were found in the lateral galleries and one egg niche was found indicating active
brood gallery construction. At this time there was evidence of light staining around the
gallery walls. Thus, from 11 days and up to 20 days, after the initial attack the presence of
adults, gallery construction, egg niches (but no eggs), and some light staining was seen.
Between the second and the third surveys egg niches were constructed and oviposition
had occurred. The first sign of eggs occurred 21 days after the initial attack and dark staining
was present in the galleries. Although by May 16, 28 days after the initial attack, adults and
eggs were present and.there was still no evidence of larvae.
In the period between May 16 and May 23, 29 and 35 days respectively after the estimated
initial attack, eggs had hatched and by the 23 May a total of 83 larvae were found. Therefore,
there was a period of 14 days after the first eggs were seen before larvae were found. Nijholt
(1978) estimated that eggs require 8-10 days to hatch. In this case, our data support that
estimate, if egg hatch had started shortly after the survey on May 16.
Larval development was evident 29 days after the initial attack, and by May 30 (after 36
days), the number of larvae present had reached a peak, and late instar larvae were present.
In addition, a few of the more advanced larval instars had developed into pupae. By June 6,
49 days after initial attack, parental adults and eggs were present and some of the pupae had
developed into teneral adults. The first empty pupal niches were found on July 11 after 84
days. At this time, larval stages were still present. In early August, 105 days after the first
signs of attack, there were no life stages present. There was an abundance of empty pupal
niches and the wood was heavily stained.
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 47
This index can be combined with harvesting and transportation data to estimate where
and when the attack could have occurred, and more importantly to predict when the adults
will emerge to overwinter. If an estimate of the time of emergence is known, decisions can
be made as to the storage location of booms to protect storage and sorting areas; or schedule
processing to use the higher risk booms at this critical time.
ACKNOWLEDGEMENTS
We thank T. Longland and D. Haines for helpful contributions, and members of the Port
Alberni Region Log Supply personnel of MacMillan Bloedel Ltd for their help and
cooperation throughout this study. This study was part of the 1990/92 Ambrosia Beetles
Task Force project which was jointly funded by MacMillan Bloedel Ltd, the Science Council
of British Columbia and Cooperative Research and Development grant No. 102678 from the
Natural Sciences and Engineering Research Council of Canada.
REFERENCES
Borden, J.H. 1988. The striped Ambrosia Beetle. Chapter 27 pp. 579-596, In. A.A. Berryman (Ed.). Dynamics of
Forest Insect Populations. Plenum Press, N.Y. 603 pp.
Chapman, J.A. 1974. Ambrosia beetle, guidelines to population estimates near dryland log-storage areas and
damage hazard assessment. Can. For. Serv., Pac. For. Res. Cen. Inf. Rep. BC-X-103.
Dyer, E.D. 1963. Attack and brood production of ambrosia beetles in logging debris. Can. Ent. 95: 624-631.
Graham, K., J.M. Kinghorn and W.E. Webb. 1950. Measurement of a damage index in logs infested by ambrosia
beetle. B.C. Lumberman 34(8):43.
Gray, D.R. and J.H. Borden. 1985. Ambrosia beetle attack on logs before and after processing through dryland
sorting areas. For. Chron. 61: 299-302.
Kinghorn, J.M. and Chapman. 1959. The overwintering of the Ambrosia Beetle 7rypodendron lineatum (Oliv.).
For. Sci. 5: 81-92.
Lindgren, B.S. 1990. Ambrosia Beetles. J. of For. 88: 8-11.
McLean, J.A. 1985. Ambrosia beetles: a multimillion dollar degrade problem of sawlogs in coastal British
Columbia. For. Chron. 61: 296-298.
McLean, J.A. 1991. Boring beetles put bite on Lumber Values. Summary of paper presented to the Forest Health
Technical Session at the Western Forestry and Conservation meeting, Victoria, B.C. December 4, 1991. 10 pp.
McLean, J.A. and J.H. Borden. 1975. Survey of Gnathotrichus sulcatus (Coleoptera:Scolytidae) in a commercial
sawmill with the pheromone sulcatol. Can. J. For. Res. 5: 586-591.
McLean, J.A. and E. Stokkink. 1988. Challenges in implementing ambrosia beetle pest management programs in
British Columbia. pp. 179-187 Jn. Payne, T.L. and H. Saarenmaa (Eds.) Integrated control of scolytid bark
beetles. Proceedings in the IUFRO Working Party and the XVII Ith International Congress of the Entomology
Symposium, Vancouver, B.C. Canada. Publ. by Virginia Polytechnic and State University, Blacksburg, VA.
Nijholt, W.W. 1978. Ambrosia Beetle: A Menace to the Forest Industry. Can. For. Res. Cen. Rep. BC-P-25. —
Richmond, H.A. 1969. Appetite for wood. Chemicals help but good woods management remains the best way to
control destructive ambrosia beetle. B.C. Lumberman 53(8): 34-36.
Richmond, H.A. and W.W. Nijholt. 1972. Water misting for log protection from ambrosia beetles in B.C. Can. For.
Serv., Pac. For. Res. Cen. Inf. Rep. BC-P-4-72.
Shore, T.L. 1985. Ambrosia Beetles. Pest Leaflet #72. Pac. For. Res. Cen. FPL 72. 4 pp.
Shore, T.L. and J.A. McLean. 1984. The effect of height of pheromone-baited traps on catches of the ambrosia
beetle Tiypodendron lineatum. J. Entomol. Soc. Brit. Columbia. 81: 17-18.
. 1985. A survey for the ambrosia beetles Tirvpodendron lineatum and Gnathotrichus retusus (Coleop-
tera:Scolytidae) in a sawmill using pheromone-baited traps. Can. Ent. 117:49-55.
Von Popo, A. and W Thalenhorst. 1974. Studies on the flight and breeding of the ambrosia‘beetle 7rypodendron
lineatum (Oliv.). Z. Angew. Entomol. 76: 251-277.
48 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
Seasonal abundance and distribution of ambrosia beetles
on the North Arm of the Fraser River, British Columbia!
DESMOND K.W. LAM AND JOHN A. MCLEAN
DEPARTMENT OF FOREST SCIENCES
THE UNIVERSITY OF BRITISH COLUMBIA
2357 MAIN MALL
VANCOUVER, B.C. V6T 1Z4
ABSTRACT
Pheromone-baited multiple funnel traps were set up on a transect to determine the
abundance and occurrence of ambrosia beetles over water and land in the Point Grey log
boom storage locations on the North Arm of the Fraser River. Beetle collections made from
April to September 1991, showed the proportion of Trypodendron lineatum, Gnathotrichus
sulcatus and G. retusus beetles were in ratio of 1,054:24:1, respectively.
Most of the ambrosia beetles were collected in the forested margin close to the shoreline.
Although there is no active logging in the adjacent Foreshore and Pacific Spirit Parks, these
areas still provide an overwintering refuge to a large number of ambrosia beetles. The
transportation of infested log booms to the North Arm of the Fraser and local wind patterns
are factors that lead to the build up of beetle numbers in the area.
INTRODUCTION
Sawmill managers detest the presence of ambrosia beetles in their sawlogs because the dark
staining galleries show up as “pinhole” defects in lumber. This damage reduces the value of
the lumber recovered from infested logs. Most of the lumber with pinholes does not end up in
lumber yards, but rather is consigned to the chipper and thence to pulp. Lumber degrade and
value losses caused by ambrosia beetles have been documented by McBride and Kinghorn
(1960). More recently, McLean (1985) suggested that the damage incurred from ambrosia
beetles infestations results in annual losses of $63.7 million in British Columbia (B.C.).
The biology of ambrosia beetles has been described by Nijholt (1978), Shore (1985),
Borden (1988) and Lindgren (1990). The three common species of ambrosia beetles found in
B.C. are Trypodendron lineatum (Olivier), Gnathotrichus sulcatus (LeConte) and G. retusus
(LeConte). All three species make their homes in the fallen branches, boles and stumps of
coniferous trees (Dyer 1963; McLean and Borden 1975a). The flight of T. Jineatum begins in
the spring. Overwintering beetles leave the duff when temperatures exceed 16°C (Kinghorn
and Chapman 1959). The beetles will hawk through the forest until arrested by suitable host
material (Moeck 1970). Although T: lineatum adults are able to fly short distances unaided,
beetle dispersal by the wind may be as far as 1.9 km from flight origin within 24 h (Salom and
McLean 1990). In the forest, the major host is the valuable old-growth sawlog. Once a
suitable host is found and the attacks initiated, the pioneering sex releases an aggregation
pheromone that attracts other beetles to the site. The first population aggregation pheromone
identified was that for G. sulcatus and it was given the trivial name, sulcatol (Borden and
Stokkink 1973). The aggregation pheromones for the other two ambrosia beetles have also
been identified and synthesized: lineatin for 7: lineatum (MacConnell et al. 1977) and retusol
for G. retusus (Borden et al. 1980).
Soon after the beetles enter into a log, eggs are laid in small niches along the galleries.
The galleries are also the growing fields for symbiotic fungi which are inoculated on to the
wood when the beetles first enter the log. The depth of gallery penetration varies among
beetle and host species. Most of the activity is confined to the moist sapwood. The
developing larvae feed solely on the fungus and remain in their niche throughout develop-
ment. The T.: lineatin larva is walled off behind a frass plug and as the larva grows, the niche
is extended. Frass is extruded through a tiny hole in the plug (Borden, 1988). The
development from egg to adult is estimated to take 70 days and the population may multiply
8-fold (Shore et al. 1987; McIntosh and McLean 1992). Gnathotrichus sulcatus and G.
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 49
retusus differ slightly from 7: lineatum in that the male is the pioneering sex. The larval
niches remain open throughout larval development but the pupa seals the niche before
pupating. The overwintering site for Gnathotrichus spp is normally within a log but it may
also successfully develop in sawn lumber (McLean and Borden 1975b). T: lineatum teneral
adults leave the log in the summer and are blown to the nearest forest margin where they
overwinter in the duff on the forest floor. At this time the teneral adults are unresponsive to
pheromones (Borden 1988).
The Point Grey booming ground is located at the mouth of the North Arm of the Fraser
River in B.C. It is an important storage area for forest companies which tow their log booms
from the northern coast to the mills in the Vancouver area. The booming ground includes
two large areas: the North Arm Jetty (NAJ) where groups of booms are tied up after arriving
from the north coast, and the Coast Mill Export (CME) ground, that covers 20 km? adjacent
to the Foreshore Park, where log booms are stored on tidal flats. These two areas, as well as
the shores of the Fraser River, are used to store booms of sawlogs in fresh water. Log booms
towed to the NAJ are moved up the river for freshwater storage, to the mills located beside
the river, or to the CME ground for resale. To the north of the main river channel and the
CME ground are the Foreshore and Pacific Spirit Parks. Both parks are mainly second
growth forest that followed harvesting in the 1930’s. Deciduous trees, shrubs and ferns
blanket the understory.
A study in spring of 1991 was conducted across the NAJ, CME grounds and into the Parks
to determine: a) the incidence of ambrosia beetles in the boom storage area and adjacent
forest foreshore area; and b) the seasonal abundance of T. lineatum, G. sulcatus and G.
retusus at the North Arm of the Fraser.
MATERIAL AND METHODS
A trapping transect was set out across the North Arm Jetty, the CME storage area, the
forested Foreshore Park area and into the Pacific Spirit Park (Fig. 1). Twenty-four multiple-
funnel traps were placed in 8 rows of three traps. The three traps within each row were baited
with ethanol and alpha-pinene. The aggregation pheromones lineatin, sulcatol and retusol
were assigned randomly to one of the three traps in each row. Traps within each row were at
least 50m apart.
The first row of traps was placed on the sandy banks of the North Arm Jetty. The second
through fifth rows of traps were placed on dolphins (groups of 4 pilings to which booms are
tied) standing between alleys in the CME ground. Access to traps on the NAJ and CME
ground was by boat. The sixth row of traps was set out half way up the foreshore cliffs while
the seventh row was set out at the top of the cliffs. Traps in row 8 were placed in Pacific Spirit
Park on the north side of Marine Drive (Fig. 1).
Traps were checked every week from Aprii through September 1991. Twenty two
collections were brought back to the laboratory for counting and identification. The daily
maximum temperature, wind direction and wind speed data for the Vancouver Airport were
obtained from the Environment Canada office in Vancouver.
RESULTS AND DISCUSSION
Many previous studies have shown that abiotic factors influence the flight of ambrosia
beetles during emergence in the spring and selection of overwintering locations in the late
summer. Temperature is a major factor that stimulates beetle activity after winter diapause.
Results from our study and others (Chapman 1962; Daterman et al. 1965; Shore and McLean
1985) show that significant 7: lineatum flights occur when temperatures in the spring are
above 15.6°C (Chapman and Kinghorn 1958). This initial peak flight is often sudden and
correlates with the adult emergence from the forest litter on the first warm days of spring.
These adults are sensitive to host odours and pheromones.
In our study, a total of 48,540 T. lineatum beetles were collected in the lineatin funnel
traps. The major T: lineatum flight started in the third week of April (Fig. 2). Very few
beetles were caught in the first week of April and the highest catches were recorded in the
50 J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
Manne Drive §=96 Pacific Spirit
Park
| ‘ees Foreshore Park
if aiianaeeials N
G/N E/F c/D A/B
North Aum Booming Ground Alleys
Jetty
Figure |. Diagrammatic cross-section of the Point Grey log boom storage area showing the relative
positions of the 8 trap lines. Each trap line consisted of three traps set out 50 m apart in an east-west
direction. See text for baiting regimes.
Trypodendron lineatum
Number of Beetles
(Thousands)
Daily Maximum Temperature (oC)
05 1219 26 03 10 17 24 31 07 14 21 28 05 12 19 26 02 09 16 23 30 06 13 20 27
APRIL MAY JUNE JULY AUGUST SEPTEMBER
Collection Period 1991
Figure 2. Weekly total catches of Trypodendron lineatum in the Point Grey log boom storage area.
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 51
last week of April. In the third week of collection, the daily maximum temperature during
April 12 to 18, exceeded the required temperature for flight on 2 of the 7 days. The beetle
catch increased from 20 to 9,016 T: lineatum beetles in two weeks. Beetle emergence from
the forest litter continued into the second week of May and finally ended in the same month.
A second, but smaller 7: /ineatum peak (“sister flight”) was observed in June and July; these
beetles represented 21% of the total beetle catch from April to September 1991. This second
peak of beetles is thought to be mainly pheromone-sensitive parent beetles that leave
infested logs at the same time as their offspring (McIntosh and McLean 1992). A few teneral
adults, which are considered to be pheromone insensitive until they have overwintered
(Borden 1988), were also caught. A proportion of the parental adults collected in the traps
could possibly establish a second brood that would emerge before year’s end. We observed
some mid-summer attack of logs by 7: lineatum but have no data on the success of these
galleries. Vigorous parents may reattack and raise a second late summer brood (Nijholt
1978).
Gnathotrichus sulcatus catches were consistently lower than T. lineatum catches (Fig. 3).
Again most of the beetles were caught in the first two months of collection. There was one
major flight of G. sulcatus beetles that occurred in early May. This peak emergence was 2 or
more weeks after the peak T- Jineatum flight. A major second G. sulcatus flight was expected
in late August (McLean and Borden 1975b), however this did not occur. One reason for the
low number of Gnathotrichus beetles in the area may have been the lack of infested logs. No
suitable host or infested material was seen within the parks. A total of 1,121 G. sulcatus and
47 G. retusus beetles were collected in the sulcatol and retusol traps, respectively.
Significantly greater numbers of 7: lineatum and G. sulcatus beetles were caught in the
two trap rows in Foreshore Park, than in Pacific Spirit Park (X2 < 0.001 in both cases). Very
few beetles were caught on the NAJ and CME dolphins (Fig. 4). Only 300 T: lineatum
beetles, half of which came from one collection on July 7th, were caught in the lineatin traps
on the row 5 dolphins of alley A/B. Total T: Jineatum and G. sulcatus catches on the NAJ and
CME ground were 1% and 4%, respectively of the total catch.
It is likely that the beetles caught in the parks originated from infested logs in storage
during June and July of the previous summer at the NAJ and in the CME booming ground.
The parental and brood adults that emerged in June, July and August were displaced by the
prevailing winds to the forested Foreshore Park area. Daterman et al. (1965) have shown that
T. lineatum and Gnathotrichus beetles are in flight between 1100 to 1700 hours. Wind
direction analysis for this time in April/May and July through September showed that for
89% of the time, the wind blew from the NAJ and CME ground towards the land.
Furthermore, wind tunnel studies have shown that ambrosia beetles are unable to maintain
directional flight at winds speeds over 1.8 km/hour (Salom and McLean 1991). Average wind
speed recorded at the airport weather station between July through September, during the
time that the beetles are thought to be in flight was 12 km/hour. The station is less than 10 km
distant.
Wind speeds of this magnitude during the dispersal flight periods support the hypothesis
that the number of beetles caught in the traps in the forested margin in 199] are a direct result
of previous summer’s wind patterns which displaced a number of the beetles emerging from
infested log booms over the water and into the forest margins. Beetles then emerged in the
subsequent spring and flew in search of suitable new host material within the forested area
where they were captured in traps. Wind patterns were suitable for flight towards the log
booms for only 10% of the time.
There is a nine month delay between the flight of brood beetles to overwintering sites in
forested areas and their reemergence the following spring to attack any suitable host material
in the area. Loggers who fall trees in the fall one year will not see signs of beetle attack on the
logs until the following spring. Managers of coastal tie-up areas must recognize that booms
stored against a forested foreshore are in a high ambrosia beetle hazard zone (Fig. 4). High
value booms would be best stored in areas that are as far as possible from forested foreshores
to prevent ambrosia beetles from attacking the floating sawlogs. The Ambrosia Beetle Task
Force that conducted a year long study on MacMillan Bloedel’s inventory in 1990/1991 found
52 J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
300
Gnathotrichus sulcatus
200
Number of Beetles
100
Daily Maximum Temperature (oC)
05 1219 26 03 10 17 24 31 07 14 21 28 05 12 19 26 02 09 16 23 30 06 13 20 27
APRIL MAY JUNE JULY AUGUST SEPTEMBER
Collection Period 1991
Figure 3. Weekly total catches of Gnathotrichus sulcatus in the Point Grey log boom storage area.
a 7 LINEATUM
(Thousands)
@. SULCATUS
Ls] @ RETUSUS
Beetle Catch Per Trap
JETTY G/H E/F C/D A/B SLOPE TOP PARK
Booming Ground Alleys Foreshore Park
Figure 4. Total seasonal catch of three species of ambrosia beetles across the Point Grey log boom
storage area and the forested foreshore area (see Fig. 1).
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 3
some degree of attack on log booms stored against forested foreshore areas while more
remote locations such as the Nanaimo River flats and the outer alleys of the Point Grey
booming ground had few fresh attacks. In this study on the North Arm of the Fraser, it is
possible that ambrosia beetles blown into the forested margin may be able to disperse out to
the beach tie up areas when the onshore winds abate. Hence, valuable sawlog booms should
be stored away from the forested margin and alley A/B during the April and May beetle flight
period.
ACKNOWLEDGEMENTS
We thank J. Howsam, K. Leonard, L. Paul and R. Robertson for their assistance in the field;
K. Lewis and R. McIntosh for review of the manuscript.
NOTE
! This study was part of the activities of the 1990-92 Ambrosia Beetle Task Force which was supported by
MacMillan Bloedel Limited, the Science Council of British Columbia and Collaborative Research and
Development grant No. 102678 from the Natural Science Engineering & Research Council.
REFERENCES
Borden, J.H. 1988. The striped ambrosia beetle, Trypodendron lineatum (Olivier). In A.A. Berryman (Ed.).
Dynamics of Forest Insect Populations. Plenum Publ. New York. pp. 579-596.
Borden, J.H. and E. Stokkink. 1973. Laboratory investigation of secondary attraction in Gnathotrichus sulcatus
(Coleoptera: Scolytidae). Can. J. Zool. 51:469-473.
Borden, J.H., J.R. Handley, J.A. McLean, R.M. Silverstein, L. Chong, K.N. Slessor, B.C. Johnston and H.R.
Schuler. 1980. Enantiomer-based specificity by two sympatric Gnathotrichus species (Coieoptera:Scolytidae).
J. Chem. Ecol. 6:445-456.
Chapman, J.A. 1962. Field studies on attack flight and log selection by the ambrosia beetle Trypodendron lineatum
(Oliv.) (Coleoptera: Scolytidae). Can. Ent. 94:74-91.
Chapman, J.A. and J.M. Kinghorn. 1958. Studies of flight and attack activity of the ambrosia beetle, Trypodendron
lineatum (Oliv.), and other Scolytids. Can. Ent. 90:362-372.
Daterman, G.E., J.A. Rudinsky, and W.P. Nagel. 1965. Flight patterns of bark and timber beetles associated with
coniferous forests of western Oregon. Oreg. State Univ. Tech. Bull. 87:46 pp.
Dyer, E.D.A. 1963. Attack and brood production of ambrosia beetles in logging debris. Can. Ent. 95:624-631.
Kinghorn, J.M. and J.A. Chapman. 1959. The Overwintering of the Ambrosia Beetle 7irypodendron lineatum
(Oliv.). Forest Sci. 5:81-92.
Lindgren, B.S. 1990. Ambrosia Beetles. J. For. 88:8-11.
MacConnell, J.G., J.H. Borden, R.M. Silverstein, and E. Stokkink. 1977. Isolation and tentative identification of
lineatin, a pheromone from the frass of 7irypodendron lineatum (Coleoptera: Scolytidae). J. Chem. Ecol.
5:549-561.
McBride, C.F and J.M. Kinghorn. 1960. Lumber degrade caused by ambrosia beetles. B.C. Lumberman.
44:40-50.
McIntosh, R. and J.A. McLean. 1992. A life stage development index for Trypodendron lineatum (Oliv.) in the Port
Alberni region of Vancouver Island. J. Ent. Soc. B.C. 89:43-47.
McLean, J.A. 1985. Ambrosia beetles: a multimillion dollar degrade problem of sawlogs in coastal British
Columbia. For. Chron. 61:295-298.
McLean, J.A. and J.H. Borden. 1975a. Gnathotrichus sulcatus attack and breeding in freshly sawn lumber. J. Econ.
Entomol. 68:605-606.
. 1975b. Attack by Gnathotrichus sulcatus on stumps and felled trees baited with sulcatol and ethanol.
Can. Ent. 109:675-686.
Moeck, H.A. 1970. Ethanol as the primary attractant of the ambrosia beetle 7irypodendron lineatum. Can. Ent.
102:985-995.
Nijholt, W.W. 1978. Ambrosia beetle: a menace to the forest industry. Can. For. Serv. Pac. For. Res. Cen. Rep. BC-
P-25.
Salom, S.M. and J.A. McLean. 1990. Dispersal of Trypodendron lineatum (Olivier) within a valley setting. Can.
Ent. 122:43-58.
Salom, S.M. and J.A. McLean. 1991. Flight behavior of scolytid beetle in response to semiochemicals at different
wind speeds. J. Chem. Ecol. 17:647-661.
Shore, T.L. 1985. Ambrosia Beetles. Can. For. Serv. Pac. For. Res. Cen. Rep. FPL-72. 4 pp.
Shore, T.L. and J.A. McLean. 1985. A survey for the ambrosia beetles Trypodendron lineatum and Gnathotrichus
retusus (Coleoptera:Scolytidae) in a sawmill using pheromone-baited traps. Can. Ent. 117:49-55.
Shore, T.L., J.A. McLean and J.C. Zanuncio. 1987. Reproduction and survival of the ambrosia beetle Trypodendron
lineatum (Oliv.)(Coleoptera:Scolytidae) in Douglas-fir and western hemlock logs. Can. Ent. 119:131-139.
54 J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
Potential insect vectors of the black stain root disease
pathogen on Southern Vancouver Island
W.R. JACOBI
PACIFIC FORESTRY CENTRE, FORESTRY CANADA, 506 WEST BURNSIDE RD.
VICTORIA B.C. CANADA V8Z IM5
CURRENT ADDRESS: DEPARTMENT OF PLANT PATHOLOGY AND WEED SCIENCE,
COLORADO STATE UNIVERSITY, FORT COLLINS CO USA 80523
ABSTRACT
Three species of beetles suspected of vectoring the black stain root disease pathogen
(Leptographium wageneri) were found at two locations on Vancouver Island, British
Columbia. The most commonly trapped specie was Hylastes nigrinus (Scolytidae) (691)
followed by Steremnius carinatus (Curculionidae) (64) and Pissodes fasciatus (Cur-
culionidae) (31). These insects may be vectors of the fungus that induces black stain root
disease but confirmatory studies are needed. Douglas-fir resin at 1% or 10% in 95% ethanol
attracted the most insects, whereas 95% ethanol or resin alone attracted the fewest. Pitfall
traps captured significantly more of all three species than window traps, and were easier to
maintain.
INTRODUCTION
Black stain root disease of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) caused by
the fungus Leptographium wageneri var. pseudotsugae Harrington & Cobb, is a serious
problem in the western U.S.A.(Cobb and Platt 1967; Harrington et al. 1983). The disease
also causes pockets of mortality on Vancouver Island and the adjacent coastal mainland of
British Columbia, although the total regional damage so far appears low. The fungus spreads
by root-to-root contacts (Hessburg and Hansen 1986) and is vectored by a root-feeding
beetle (Hylastes nigrinus Mann.) and weevils (Steremnius carinatus (Boh.), and Pissodes
fasciatus (LeC.)) that attack stressed trees (Hansen et al. 1988).
Recent studies on resistance and mortality rates of black stain root disease, raised
questions as to the occurrence of vectors at study sites on Vancouver Island (Jacobi,
unpublished data). Steremnius carinatus and Pseudohylesinus nebulosus LeConte were
found previously in black stain affected stands on the Island but the pathogen was not found
on these insects (Morrison and Hunt 1988). No previous record appears to exist of Pissodes
or Hylastes activity in areas affected by black stain.
Thus the two objectives of this study were to determine how most efficiently to attract and
trap these insect species and to determine if potential vectors of the pathogen were present at
two black stain disease centers on Vancouver Island.
MATERIALS AND METHODS
The two study plots were near Sooke and Port Renfrew B.C. on southern Vancouver Island.
The Sooke plot was in a naturally regenerated Douglas-fir stand, 18 yr old, 13 km north of
route 14 and 0.2 km west of the Butler Main line. The Port Renfrew plot was in a 21 yr old
planted Douglas-fir provenance trial about 7 km east of Port Renfrew off the Lens Creek
main line. Both plots were active centers of black stain root disease with trees showing a
range of symptoms from near healthy to dead. Black stains, diagnostic of black stain root
disease, were found on roots and root collar of declining trees.
Twelve insect traps were placed at each plot from April to June 1990 to determine which
potential insect vectors were present. Four traps, located around an affected tree, were
placed at three sites within each plot. Three traps were nondirectional window types,
consisting of two 30 xX 30 cm clear plastic “windows”, a collecting funnel and a jar
containing 10% antifreeze solution. Plastic tops were placed on the traps to exclude rain. The
traps were suspended 0.8 m above the ground from posts driven into the ground at an angle.
2D
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
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56 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
Baits for the three window traps consisted of 95% ethanol, 1% Douglas-fir resin in 95%
ethanol, or 100% resin. The resin was collected previously from a cut stump and used
because turpentine is a good attractant (Payne et al. 1978). One pitfall trap was placed at each
of the three sites. The trap was a plastic Multipher(R) trap (Biocontrol Services, Ste Foy,
Quebec, Canada) placed in the ground with a jar filled with 10% antifreeze inside to collect
the insects. Bait for the pitfall traps was 10% resin in 95% ethanol. The baits were placed in
35 mm plastic film canisters with four 2 mm holes in each lid. Elution rates of the baits were
20-30 ml of 95% ethanol per 14 days. Baits were suspended half way down the “windows”
and on the under side of the pit trap lids.
Collections were made every 10-14 days and the numbers of Hylastes, Pissodes and
Steremnius were recorded. Insects were identified by H. A. Moeck and R. Duncan,
entomologists at the Pacific Forestry Centre, Victoria B.C.. A Chi-square analysis tested for
uniform distribution of insect counts by species collected among four baits in both trap types
and among three bait types in window traps.
RESULTS AND DISCUSSION
Three insect species suspected of vectoring Leptographium wageneri were found at both
locations (Table 1). The most commonly trapped insect species was Hylastes nigrinus (691)
whereas Steremnius carinatus (64) and Pissedes fasciatus (31)were found less often. Only
seven Pseudohylesinus nebulosus were trapped in window traps and one in a pitfall trap.
Morrison and Hunt (1988) captured P. nebulosus in trap log sections which may be more
attractive than the resin bait used in this study.
Window traps collected both flying insects, Hylastes and Pissodes, but only one of the
flightless Steremnius. Pitfall traps collected significantly (P = 0.01) more of all three insect
species than the window traps (Table 1). All baits attracted insects, but in the window traps
1% resin attracted significantly (P = 0.01) more Hylastes than 100% resin or 95% ethanol.
Few Pissodes and Steremnius were collected by window traps and there were no significant
differences in numbers of these species attracted by the three baits. Pitfall traps are adequate
to monitor these three insects and are much easier to maintain than window traps.
Although the presence of these insect species in black stain root disease centers is now
confirmed, no isolations for L. wageneri were attempted to establish that these potential
vectors were indeed vectoring the black stain root disease pathogen. Further studies are
needed to address the relative importance of insect vectoring versus root contact as means
for infecting regenerating Douglas-fir in black stain disease areas.
ACKNOWLEDGEMENTS |
This werk was completed at the Pacific Forestry Centre, Forestry Canada, Victoria B.C.
while the author was a visiting scientist.
I appreciate the help and advice of D. Craigdallie, T.G. Gray, R. Duncan, R.S. Hunt, A.
Johnson, D.A. Linton, H.A. Moek, and L. Safranyik, Pacific Forestry Centre, Forestry
Canada, Victoria B.C..
REFERENCES
Cobb, EW., Jr., and W.D. Platt. 1967. Pathogenicity of Verticicladiella wagenerii to Douglas-fir. Phytopathology
57:998-999.
Hansen, E.M., D.J. Goheen, PF Hessburg, J.J. Witcosky, and T.D. Schowalter. 1988. Biology and management of
black-stain root disease in Douglas-fir. In Leptographium root diseases on conifers. Edited by T.C. Harrington
and EW. Cobb, Jr. American Phytopathological Society Press, St. Paul, MN. 149 p.
Harrington, T.C., C. Reinhart, D.A. Thornberg, and FW. Cobb Jr. 1983. Association of black-stain root disease
with precommercial thinning of Douglas-fir. For. Sci. 29:12-14.
Hessburg, PF, and E.M. Hansen. 1986. Mechanisms of intertree transmission of Ceratocystis wageneri in young
Douglas-fir. Can.J. For. Res. 16:1250-1254.
Morrison, D.J. and R.S. Hunt. 1988. Leptographium species associated with root disease of conifers in British
Columbia. In Leptographium root diseases on conifers. Edited by T.C. Harrington and FW. Cobb, Jr. American
Phytopathological Society Press, St. Paul, MN. 149 p.
Payne, T.L., J.E. Coster, J. V. Richerson,L.J. Edson, and E.R. Hart. 1978. Field response of the southern pine beetle
to behavioral chemicals. Environ. Entomol. 7:578-582.
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 a7
Distribution of economically important, wood-infesting
anobiid beetles in the Pacific Northwest
DANIEL A. SUOMI AND ROGER D. AKRE
DEPARTMENT OF ENTOMOLOGY
WASHINGTON STATE UNIVERSITY
PULLMAN, WA 99164
ABSTRACT
Structure-infesting anobiid beetles were surveyed in Washington State homes and outbuild-
ings during 1987-91. Hemicoelus (= Hadrobregmus) gibbicollis (LeConte) was found in
virtually all of the 90 structures inspected and is the predominant species infesting building
timbers. This anobiid is known primarily from coastal areas of western North America.
Hadrobregmus quadrulus (LeConte) was discovered in 5.5% of infested structures while
Xestobium affine LeConte and Priobium punctatum (LeConte) were found in only 2% of —
infested buildings. The curculionid, Rhyncolus brunneus Mannerheim, also infests struc-
tural timbers and was present in 8% of buildings examined in this study.
INTRODUCTION
Wood-infesting beetles in the family Anobiidae are serious structural pests in many areas of
the world. Larvae cause extensive damage by feeding and tunneling within timbers resulting
in weakened structures. Considerable resources are often expended for wood replacement
and/or chemical controls. Unfortunately, little is known about most species despite the
extensive damage they cause. Long life cycles and extreme difficulty in rearing the beetles
has resulted in this dearth of information.
Certain anobiid species are well known, and many notable infestations have been
recorded from wooden structures during the 20th century. Baines (1914) reported a serious
infestation of the deathwatch beetle, Xestobium rufovillosum (De Geer), in oak timbers
supporting the slate roof of Westminster Hall in London. The widespread damage resulted in
extensive replacement of wood with steel supports and provided a major impetus to conduct
the first biological studies on anobiid beetles. Prior to that time anobiids were mostly
considered to be a curiosity. While in dry dock for repairs, H.M.S. Victory, an 18th century
wooden ship of the British Navy, was found to be infested by the same beetle species (Fisher
1940). In order to address damage caused to oak timbers and furniture in England by X.
rufovillosum, the Forest Products Research Laboratory was created (Fisher 1938). An attack
by this insect on oak timbers in the Old South Meeting House in Boston, Massachusetts was
reported by Muirhead (1941). Engineers assessing the damage to tower supports noted that
the hurricane of 1938 would probably have destroyed them if the building had not undergone
earlier repairs.
Another anobiid, Fuvrilletta peltata (Harris) [=Xvyletinus peltatus (Harris)], was
identified as infesting a home in North Carolina (Wright 1959) and stimulated interest in
wood-destroying species in the United States. Moore (1968, 1970), Williams (1977, 1983),
Williams and Mauldin (1974, 1981), and Williams and Waldrop (1978) conducted research
projects on EF. peltata, including life cycle studies, types of wood infested, and control
options. Earlier work by Simeone (1960) found Hemicoelus carinatus (Say) to be the most
frequently encountered wood-infesting anobiid in northeastern North America. Doane et al.
(1936) cited examples of structures in the western states being damaged by various anobiid
beetles, including Hadrobregmus quadrulus (LeConte), Hemicoelus (= Hadrobregmus)
gibbicollis (LeConte), and Priobium punctatum (LeConte).
The furniture beetle, Anobium punctatum (De Geer), 1s probably the best known wood-
infesting anobiid. Various researchers (Becker 1940; Kelsey et al. 1945; Hickin 1949, 1960,
1981; Bletchly 1952, 1957; Spiller 1952; Fisher 1958; Berry 1976) have published on this
species. This is the most serious wood-destroying pest throughout England and much of
58 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
northern Europe, far more damaging than termites or any other group of insects (Hickin
1975). Additionally, Denne et al. (1944) noted that the furniture beetle was a widespread
problem in New Zealand. Antique furniture shipped to the United States from Europe has
typically been fumigated with methyl bromide to prevent the beetle’s spread.
Anobiid beetles in the Pacific Northwest (PNW) are largely unidentified (Hatch 1962).
However, infestations of these insects are regularly reported to various agencies throughout
the region. An initial goal of this research was to identify those species causing structural
damage in the PNW.
MATERIALS AND METHODS
Collection data.
Anobiid beetles are difficult to collect (White 1969). Cryptic coloration and a tendency to
remain immobile, except when seeking a mate, contribute to this difficulty. Therefore,
efforts were initially concentrated on reviewing collection specimen data from researchers
and coleopterists who had made anobiid collections in the PNW. Entomologists from seven
major collections were contacted, and the most prevalent beetle species were then tallied. In
addition, pest control operators and extension specialists submitted specimens to us from
1987 to 1991.
Collection and rearing of beetles.
Ninety anobiid-infested structures were examined, primarily in western Washington,
although collections were also made in eastern Washington, western Oregon, and Oakland,
California. Infested wood was removed from crawl spaces and basements, transported to the
laboratory at Washington State University, Pullman, and stored in 33 gal emergence
containers where environmental conditions simulated the moderate temperatures and high
relative humidity found in western Washington. Emergence containers remained under
constant temperature and relative humidity (18 + 1°C and 65 + 3% RH). Certain containers
were placed out-of-doors from 1987-91 to observe the effects of extreme heat and cold (as
found in eastern Washington) on beetle survival. Maximum and minimum temperatures
attained within the containers were recorded during 1987-90. Emerging beetle adults were
collected throughout the year and identified. A standard size sweep net (38 cm diam) was
used during summer months to sample forested areas for beetle adults in western Washing-
ton and Oregon.
RESULTS AND DISCUSSION
Primary, structure-infesting anobiid beetles.
After much correspondence, analyses of various insect collections, and visits to anobiid-
infested structures, it became apparent that one species predominated over all others
combined. Hemicoelus gibbicollis, the most common species, was recovered from all 90
study sites and is known to infest structures from Alaska to California (Linsley 1943). This
anobiid has caused extensive damage in subfloor areas of buildings (Doane et al. 1936).
Nevertheless, Furniss and Carolin noted in 1977 that the biology of H. gibbicollis was still
incompletely recorded. Thus, when the overall importance of this species was studied,
efforts were also focused on its distribution.
Hemicoelus gibbicollis was initially described from collections made in California by
LeConte (1859), and in succeeding years the records became more widespread. Doane et al.
(1936) first reported this anobiid as vigorously attacking beams of Douglas-fir, Pseudotsuga
menziesii (Mirbel), in old bridges, barns, and basement timbers in the San Francisco area.
Linsley (1943) referred to this species as the California deathwatch beetle and documented a
number of infested structures in California and Oregon. Hatch (1946) produced the first
evidence of this insect attacking wooden timbers in Washington. Spruce boards in the porch
of a residence on the Olympic Peninsula were badly infested and required replacement. This
beetle is probably the primary wood-infesting anobiid in California, Oregon, and Washing-
ton. Building inspections conducted during 1984 by Jan and Red Butler, Angeles Pest
Control, showed H. gibbicollis to be the only species collected in Port Angeles and Sequim,
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 59
Clallam County, Washington (Suomi 1992: appendix |). These localities are within some of
the most heavily infested areas of the state.
Melville H. Hatch, the preeminent coleopterist in the Pacific Northwest, collected a
significant number of H. gibbicollis near the Long Beach Peninsula of southwestern
Washington (Hatch and Kincaid 1958). His records do not indicate whether these insects
were captured while sweeping forested areas, or if he gathered infested wood and later
collected emerging adults. In our experience it is extremely difficult to sweep heavily
forested areas for these beetles, so beating trays or other collecting methods may have been
utilized. The greatest collecting successes result when wood from infested structures is
obtained, and emerging adults are captured under controlled conditions.
Most collections of H. gibbicollis have been made along coastal areas of the western
United States, Canada, and Alaska (Suomi 1992: appendix 2). No collections Have been
reported from coastal areas south of California probably because the climatic conditions are
too dry to favor larval survival. Two unusual sites were reported from Glacier National Park,
Montana and Yellowstone National Park, Wyoming (Fig. 1). These probably represent
atypical records, and the native range for this insect is along the Pacific Coast of North
America. One other noteworthy collection site was in Yakima County, Washington, near
Mt. Rainier National Park. Although H. gibbicollis can survive the extreme climatic
conditions found in eastern Washington (Table 1), most collections were made in the milder
climatic zones along coastal areas (Fig. 2, Suomi 1992: appendix 3).
Table 1
Temperature extremes (°C) in emergence containers and numbers of H. gibbicollis that emerged in
eastern Washington.
Year Maximum Minimum No. Emerged
1987 35.0 = Ke, 4
1988 34.5 = 2055 14
1989 39.5 27) 16
1990 36.5 = 18.0 82
Secondary, structure-infesting anobiid beetles.
Linsley (1943) and White (1982) described a number of anobiid species as capable of
causing structural damage in the western states. However, during the building inspections
conducted, only three anobiid species, in addition to H. gibbicollis, were recovered.
Hadrobregmus quadrulus is a known wood-infesting species but was only found in 5.5% of
infested structures. This beetle is commonly associated with the wood-destroying fungus,
Meruliporia incrassata (Berkeley and Curtis) Murrill [= Poria incrassata (Berkeley and
Curtis) Burt], which produces dry, rotten wood (Hatch 1962). Chamberlin (1949) recovered
H. quadrulus from Douglas-fir beams in Oregon, while Spencer (1958) reported this species
from numerous houses in Vancouver, British Columbia.
Xestobium affine LeConte was somewhat less abundant and occurred in 2% of homes
investigated. This anobiid had not previously been reported to infest structural timbers. On
five separate occasions, adults of X. affine tapped their frons on a glass surface, approx-
imately 20-30 times during a 5 sec period, and repeated this procedure 3-4 times. Rapid
tapping with a wooden pencil also elicited a tapping response from the insect. Birch and
Keenlyside (1991) reported similar behavior by X. rufovillosum which probably serves in
mate location. At one time this tapping was associated with a death in the household and led
to the name deathwatch beetles for the family Anobiidae (Gahan and Laing 1932). These,
along with H. gibbicollis, were the only anobiids captured while sweeping forested areas.
60 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
BRITISH CANADA
_COLUMBIA
WASHINGTON
=. |
RLY 7 3
OREGON ae
ei
i SS
CA
( UTAH
CALIFORNIA eo
Figure 1. Hemicoelus gibbicollis distribution, western United States.
BRITISH COLUMBIA
VANCOUVER
OREGON
Figure 2. Hemicoelus gibbicollis collection sites( + ); Washington, 1987-91.
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 61
Priobium punctatum was found in 2% of the homes examined. Chamberlin (1949)
reported this anobiid from oak flooring and furniture in California. The beetle was more
common in eastern Washington and readily appeared at blacklight traps. Another structure-
infesting member of this genus, P. sericeum (Say), had been collected in eastern Washington
homes and damaged flooring, woodwork, and furniture (White 1982). It was not found in
any structure during this study. No collections were made of A. punctatum or X.
rufovillosum. Hatch (1938) reported A. punctatum as occurring in Washington, but this may
have been a result of wood being imported from infested areas.
An unexpectedly large number of collections were made of the curculionid beetle,
Rhyncolus brunneus Mannerheim. Although Hatch (1971) described members of this genus
as living under the bark of dead trees, these insects were discovered in 8% of infested
structures and appeared to move in after the wood had been attacked by an anobiid, usually
H. gibbicollis. Larvae and adults were found in surface layers of the wood and produced
round, shiny, golden brown frass that is quite distinct from that of anobiids. Chamberlin
(1949) noted that Rhyncolus larvae live in sapwood and damage wood in much the same way
as anobiid larvae. This species is found in the wood of many conifers but prefers the drier
portions. Little is known about its habits (Hatch 1962).
ACKNOWLEDGEMENTS
We thank Jan and Red Butler, Terry Whitworth, Fred Ellis, and many other pest control
operators in Washington and Oregon for their help in locating anobiid-infested structures.
We thank the curators of the following collections for assistance in documenting the
distribution of H. gibbicollis: California Academy of Sciences, Golden Gate Park, San
Franciso, CA; James Entomological Collection, Washington State University, Pullman, WA;
Museum of Comparative Zoology, Harvard University, Cambridge, MA; Oregon State
University Entomological Museum, Corvallis, OR; Systematic Entomology Laboratory,
U.S. National Museum, Washington, D.C.; Spencer Entomological Museum, University of
British Columbia, Vancouver, B.C.; and UCR Entomological Teaching and Research
Collection, University of California, Riverside, CA. We also thank Richard E. White,
Systematic Entomology Laboratory, for assistance with the anobiid identifications and Brian
Raynes for help in collecting beetle-infested wood.
REFERENCES
Baines, F 1914. Report on the roof of Westminster Hall. Cd. paper 7436.
Becker, G. 1940. Beobachtungen tiber schadlichkeit, frass, und entwicklungsdauer von Anobium punctatum de
Geer ("Totenuhr’). Z. Pflanzenkr. Pflanzenschutz 50: 159-172.
Berry, R. W. 1976. Laboratory rearing of Anobium punctatum. Mater. Org. 1: 171-182.
Birch, M. C. and J. J. Keenlyside. 1991. Tapping behavior is a rhythmic communication in the death-watch beetle,
Xestobium rufovillosum (Coleoptera: Anobiidae). J. Insect Behav. 4(2): 257- 263.
Bletchly, J. D. 1952. A summary of some recent work on the factors affecting egg-laying and hatching in Anobium
punctatum De G. (Coleoptera-Anobiidae). Proc. [Xth Int. Congr. Entomol. 1: 728-734.
. 1957. The biological work of the Forest Products Research Laboratory, Princes Risborough. HI. The
work of the Entomology Section, with particular reference to the common furniture beetle, Anobium punctatum
DeG. Proc. Linn. Soc. London 168: I1I-115.
Chamberlin, W. J. 1949. Insects Affecting Forest Products and Other Materials. Oregon State College Coop.
Assoc., Corvallis. 159 p.
Denne, W., D. Spiller, and J. M. Kelsey. 1944. Research on Anobium punctatum deGeer. The flight period at
Auckland. N. Z. J. Sci. Technol. Sect. A. 26: 152-154.
Doane, R. W., E. C. Van Dyke, W. J. Chamberlin, and H. E. Burke. 1936. Forest Insects. McGraw Hill, New York.
463 p.
Fisher, R. C. 1938. Studies of the biology of the death-watch beetle, Xestobium rufovillosum DeG. IL. The habits of
the adult with special reference to the factors affecting oviposition. Ann. Appl. Biol. 25: 155-180.
————.. 1940. Studies of the biology of the death-watch beetle, Xestobium rufovillosum DeG. III. Fungal decay
in timber in relation to the occurrence and rate of development of the insect. Ann. Appl. Biol. 27: 545-557.
. 1958. Current problems in woodworm control. A survey of recent developments. Ann. Appl. Biol.
46(1): 111-117.
Furniss, R. L. and V. M. Carolin. 1977. Western Forest Insects. USDA For. Serv. Misc. Pub. 1339. 654 p.
Gahan, C. J. and EF Laing. 1932. Furniture Beetles. Brit. Mus. Nat. Hist. Econ. Ser. 11. 24 p.
Hatch, M. H. 1938. The furniture beetle, Anobium punctatum Deg., in Washington. J. Econ. Entomol. 31(5): 545.
62 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
————. 1946. Hadrobregmus gibbicollis infesting woodwork. J. Econ. Entomol. 39(2): 274.
————.. 1962. The Beetles of the Pacific Northwest. III]. Univ. Wash. Press, Seattle, Washington. 503 p.
. 1971. The Beetles of the Pacific Northwest. V. Univ. Wash. Press, Seattle, Washington. 662 p.
Hatch, M. H. and T. Kincaid. 1958. A List of Coleoptera from the Vicinity ot Willapa Bay, Washington. The
Calliostoma Co., Seattle, Washington. 21 p.
Hickin, N. E. 1949. The common furniture beetle, Anobium punctatum de Geer (Col. Anobiidae). Entomol. Mon.
Mag. 85: 213-214.
. 1960. The problem of wood damage by Anobium punctatum de Geer in the United Kingdom, with some
notes on the current commercial practice of control. Proc. XIth Int. Cong. Entomol. 2: 321-326.
. 1975. The Insect Factor in Wood Decay. Associated Business Programmes, London. 383 p.
. 1981. The Woodworm Problem. 3rd ed. Hutchinson, London. 123 p.
Kelsey, J. M., D. Spiller, and R. W. Denne. 1945. Biology of Anobium punctatum.N. Z. J. Sci. Technol. Sect. B..27:
59-68.
LeConte, J. L. 1859. Additions to the coleopterous fauna of northern California and Oregon. Proc. Acad. Nat. Sci.
Philadelphia 11: 281-286.
Linsley, E. G. 1943. The recognition and control of deathwatch, powderpost, and false powderpost beetles. Pests
I: 11-14.
Moore, H. B. 1968. Development and longevity of Xyletinus peltatus under constant temperatures and humidities.
Ann. Entomol. Soc. Am. 61(5): 1158-1164.
. 1970. Incubation time of eggs of Xyletinus peltatus (Coleoptera: Anobiidae) under constant tempera-
tures and humidities. Ann. Entomol. Soc. Am. 63(2): 617-618.
Muirhead, D. M. 1941. A beetle control problem in timbers of the Old South Meeting House. J. Econ. Entomol.
34(3): 381-383.
Simeone, J. B. 1960. Survey of wood-feeding Anobiidae in northeastern United States, including a study of
sai ats and humidity effects on egg development of Hadrobregmus carinatus (Say). Proc. X1th Int. Congr.
Entomol. 2: 326-335.
Spencer, G. J. 1958. The insects attacking structural timbers and furniture in homes in coastal British Columbia. J.
Entomol. Soc. Brit. Columbia 55: 8-13.
Spiller, D. 1952. A study of control of infestations of the common house-borer, Anobium punctatum de Geer. N. Z.
J. Sci. Technol. Sect. B. 33: 447-459.
Suomi, D. A. 1992. Biology and management of the structure-infesting beetle, Hemicoelus gibbicollis (LeConte)
(Coleoptera: Anobiidae). Ph.D. dissertation, Washington State Univ., Pullman 166 p.
White, R. E. 1969. Field note. Coleopt. Bull. 23: 102. 107.
———.. 1982. A Catalog of the Coleoptera of America North of Mexico, family Anobiidae. USDA Handb.
529-70. 58 p.
Williams, L. H. 1977. Responses of Xyletinus peltatus ((Harris) Coleoptera: Anobiidae) larvae to favorable and
unfavorable temperatures. Mater. Org. 12(1): 59-67.
. 1983. Wood moisture levels affect Xyletinus peltatus infestations. Environ. Entomol. 12(1): 135-140.
Williams, L. H. and J. K. Mauldin. 1974. Anobiid beetle, Xvletinus peltatus (Coleoptera: Anobiidae), oviposition
on various woods. Can. Entomol. 106: 949-955.
. 1981. Survival and growth of the anobiid beetle, Xvletinus peltatus (Coleoptera: Anobiidae), on various
woods. Can. Entomol. 113: 651-657.
Williams, L. H. and J. D. Waldrop. 1978. Xyletinus peltatus seasonal flight, diel activity, and associated
environmental influences. Ann. Entomol. Soc. Am. 71(4): 567-574.
Wright, C. 1959. Beetles found in yellow pine floor joists of buildings in North Carolina. J. Econ. enor 52(3):
452.
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 63
Characteristics of structures attacked by the
wood-infesting beetle, Hemicoelus gibbicollis
(Coleoptera: Anobiidae)
DANIEL A. SUOMI AND ROGER D. AKRE
DEPARTMENT OF ENTOMOLOGY
WASHINGTON STATE UNIVERSITY
PULLMAN, WA 99164
ABSTRACT
The anobiuid, Hemicoelus gibbicollis (LeConte), is the most serious structure-infesting
beetle along the Pacific Coast. This species attacks damp timbers (13-19% moisture content)
in crawl spaces, basements, and outbuildings. In structures monitored for anobiids,
Douglas-fir, Pseudotsuga menziesii (Mirbel), was the most abundant and readily attacked
wood species, but other timbers used in building construction were also infested. Sapwood is
more seriously infested than heartwood, and wood of any age can be attacked. Sill plates,
rim joists, and headers adjacent to concrete foundations are among the most seriously
damaged timbers. Infested buildings ranged from 8 to 122 years old, x = 63.2. Infestations
persist for many years. New, air-tight houses built with an abundance of sapwood in
construction timbers may be at risk of beetle attack unless moisture levels are kept at a
minimum.
INTRODUCTION
Infestations attributed to powderpost beetles have been reported from structures along the
Pacific Coast of western North America for more than 50 years (Doane et al. 1936, Hatch
1946, Chamberlin 1949). Examinations of infested timbers showed that deathwatch beetles
(Coleoptera: Anobiidae) were responsible for most of the damage. Larval feeding over a
period of years often resulted in a weakened structure, necessitating replacement of timbers.
The anobiid, Hemicoelus (= Hadrobregmus) gibbicollis (LeConte), was ultimately impli-
cated as the primary pest species (Linsley 1943). Despite the seriousness of numerous
infestations, the biology of this beetle remained incompletely recorded for many years
(Furniss and Carolin 1977).
Although lacking adequate biological information, pest control operators (PCOs) rou-
tinely apply insecticides as structural treatments for anobiids. Evaluation of beetle activity
within timbers is extremely difficult and many buildings are still being treated for inactive
infestations. Most PCOs rely on the presence of adult exit holes as their main indication of
anobiid activity, but this has been shown to be unreliable (Suomi 1992). Williams et al.
(1979) stated that the number of exit holes does not necessarily indicate the activity of an
infestation; only the existence of larvae does. Radiography is the most reliable method for
determining numbers of larvae present within wood but it is impractical for field use. The
presence of larval frass expelled from adult beetle emergence holes can be used as an
indicator of activity. Frass the color of freshly produced sawdust often reveals on-going
larval feeding within timbers.
Hemicoelus gibbicollis is found primarily in damp timbers of crawl spaces, basements,
barns, and outbuildings in humid coastal areas of western North America. Analyses of
museum collections from western states and surveys conducted in Washington and Oregon
have failed to identify this species from dry, inland areas (Suomi 1992).
MATERIALS AND METHODS
Data Collection From Infested Structures.
During 1987-91 PCOs, extension specialists and county agents, and homeowners
contacted us with information on houses or outbuildings with possible anobiid beetle
infestations. From >120 potential sites, we selected 90 structures (3 log houses, II
64 J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992
outbuildings, and 76 frame houses; 9 with a basement and 67 with a crawl space) in western
Washington and Oregon which were infested with H. gibbicollis. Buildings with inaccess-
ible infestations, those having been chemically treated, or structures with unknown histories
were excluded. A survey form (Suomi 1992: appendix 6) was developed to record site
conditions. Efforts were made to collect all available historical data from each building
owner.
In all cases, damaged timbers were collected for positive identification of the infesting
insect species. Wood moisture content readings were taken with a Delmhorst Model RC-1C
Moisture Meter (Delmhorst Instrument Company, Boonton, New Jersey) or a Mini-Super
Wood Moisture Meter (Protimeter, Meter House, Marlow, Bucks, England). Efforts were
made to take readings from sound and infested wood to check for differences. Temperature
and relative humidity (RH) readings were recorded with a Hanna Thermohygrometer Model
HI 8564 (Cole-Parmer Instrument Company, Chicago, Illinois). All readings were taken
from five locations within the structure and mean values determined.
Simulated Crawl spaces.
In Pullman (eastern Washington) and Puyallup (western Washington), two simulated
crawl spaces were made from 39.4 x 19.1 x 19.1 cm concrete foundation blocks. Each
structure was located near buildings with crawl spaces, but away from areas that could be
disturbed by humans. Interior dimensions of the simulated crawl spaces measured 161.3 X
41.9 X 58.4 cm. A peaked roof was constructed from 1.9 cm (7/4") plywood, covered with
tar paper to allow water runoff, and mounted on hinges. The structure was partitioned into
three separate compartments with 1.9 cm plywood (Fig. 1). The first compartment had a soil
substrate and no ventilation, other than air entering between the wood/block interface; the
second had no additional ventilation, but a 6 mil vapor barrier was used to cover the
substrate; and the third compartment had a 6 mil vapor barrier and one vent (30.5 x 11.4
cm) which was covered by a metal screen (0.24 cm? openings). Temperature and RH within
each compartment were registered on a Jumbo Dial (Thermometer Corporation of America,
Springfield, Ohio) and recorded every two weeks for 18 months in Pullman and Puyallup. In
addition, readings of wood moisture content were taken from two wood blocks kept in each
of the three separate compartments for 18 months, at the Pullman site only.
VAPOR PO
BARRIER ee vere
1 : £)
Figure 1. Simulated crawl space design for monitoring temperature and relative humidity. The
compartments were of equal size.
J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992 65
Table 1
Wood moisture levels in structures! infested with Hemicoelus gibbicollis.
Wood moisture No. of % of
content (%) structures structures
12 I 1.6
13 Ta Li
14 8 i255
5) 12 18.7
16 11 Pie2
17 Ke) 23.4
18 4 Guz
19 l 1.6
21 | 1.6
itotal of 64 structures, wood moisture meters unavailable during 1987 field season.
RESULTS AND DISCUSSION
Natural Infestations.
Hemicoelus gibbicollis is primarily an economic concern in houses with crawl spaces or
damp basements, but will infest any suitable structural timbers. Williams and Smythe (1978)
reported that >99% of 673 beetle (primarily anobiid) infestations in Arkansas were located
in crawl spaces beneath houses. The most susceptible wood for a natural anobiid infestation
is sapwood from dead standing trees or stumps that remains undecayed for at least 3 years,
because most wood-infesting anobiids have a 3 year life cycle in nature (Berry 1976).
Sapwood in contact with the ground will be totally decayed by wood-destroying microorga-
nisms in 3 years or less (Shigo 1968), so anobiids are often unable to complete development
in this decomposing wood.
During these investigations we observed six structures that were probably infested from
stumps left in the crawl space area. Wooden debris, in contact with the substrate, that
remained after construction was completed could also serve as the initial infestation site.
Undecayed stumps, plywood form boards, and even wooden tools often were seriously
infested. The beetles would then move into the substructure.
Wood Moisture.
Probably the most important factor that allows these beetles to survive and reproduce is
wood with a moisture content between 13 and 19% (Table 1). Levels above 19% led to
development of molds or other microorganisms which effectively reduce the numbers of
eggs and larvae. On two occasions, larvae were found in wall studs on shaded sides of homes
(usually north) when the wood moisture content was >19% within the substructure. Wood
with moisture content levels below 12% resulted in reduced larval populations (Suomi 1992).
Areas of homes normally exposed to sunlight may dry out enough to reduce or prevent
anobiid survival. Generally, the moisture content of wood in eastern Washington structures
remains below 12%, which prevents H. gibbicollis from infesting structural timbers east of
the Cascade Mountains. Relative humidity and therefore wood moisture content within the
vapor barrier and vented compartments of mock crawl spaces in both eastern (Fig. 2a) and
western Washington (Fig. 2b) remained significantly lower than the portion with only a
vapor barrier or no treatment (Table 2). However, these values were considerably higher than
are typically found in eastern Washington because the simulated crawl space was in a poorly
drained location. Wood moisture content readings were approximately 2% less in simulated
crawl space compartments with ventilation or a vapor barrier or both (Table 3).
Hosts.
In nature, H. gibbicollis larvae attack a wide variety of softwoods and hardwoods
(Knutson 1963). Douglas-fir, Pseudotsuga menziesii (Mirbel), was the primary structural
66 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
timber species infested (97.8%), due in large part to its widespread use in building
construction. Western red cedar, Thuja plicata Don, and western hemlock, Tsuga hetero-
phylla (Rafinesque) were attacked in about 2% of the structures examined.
Table 2
Temperature and relative humidity data from simulated crawl spaces in eastern and western
Washington.
Treatment Temp. range (°C) x + SEM RH range (%) x + SEM
Western
Washington
VB+ V! —4.0 - 25.5 Megas? 27 - 42 G4), s40v72
VB Oe 2D 10.4 43 30 - 41 6y/5) as (ee
NONE —4,5 - 24.0 OOF = lel 31 - 44 37.9) =) 076"
Eastern
Washington
VB+V =4.5- 20:5 E82 Mal 37-50 45.1 + 0.42
VB —4.0 - 21.0 128) 22107] 37 - 54 AG 32 (0.52
NONE 375. =20 0 Te aseuOl 38 - 56 505.5052
Means (RH) followed by the same letter do not differ significantly (P = 0.05) based on t tests (SAS
Institute 1985).
'V = vent; VB = vapor barrier; NONE = neither treatment.
Authorities (Linsley 1943, Chamberlin 1949, Ebeling 1975, Hickin 1981, Mampe 1982)
have stated that anobiid beetles will only attack wood that is well seasoned or has been in
service at least 20 years. This is not always the case with H. gibbicollis (Table 4). Exit holes
produced by emerging adult beetles may not become immediately obvious because the
insect can spend up to six years as a larva (Suomi 1992). Moreover, the inaccessible nature of
many infestations often prevents their discovery for 20 years or more.
New timbers, cut from trees containing increased sapwood grown in short rotation
forests, can become seriously infested in only a few years. We have seen at least seven
structures that showed signs of larval activity and adult emergence in replacement timbers
that were present for <7 years. Infested buildings ranged from 8 to 122 years old, with an
average age of 63.2 years. Williams and Smythe (1978) determined that anobiid-infested
houses in Georgia and Mississippi ranged from 9 to >100 years old, with an average age of
about 37 years.
Williams and Barnes (1979) have ascertained that well designed floor systems should
adequately compensate for any weakening caused by the anobiid, Euvrilletta peltata
(Harris) [=Xyletinus pelatus (Harris)]. Within structural timbers, numbers of H. gib-
bicollis larvae are often much greater (Suomi 1992) and therefore weakened timbers should
be promptly replaced. Several PCOs in the Pacific Northwest have unwisely recommended
placing an untreated floor joist between infested joists to strengthen the floor and avoid
chemical treatment of the structure. Because of the potential for rapid anobiid attacks on
these timbers, this practice must be discouraged.
Infestation Sites.
Hemicoelus gibbicollis adults are poor fliers, so many infestations may be established by
beetles that walk to the structure (Suomi 1992). Natural openings such as crawl space
entrances or vents usually serve as initial infestation sites. Sill plates, rim joists, and headers
adjacent to concrete foundations are among the most seriously damaged timbers. As an
infestation progresses, any area within the substructure can be attacked.
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 67
The outer edges of floor and rim joists were often seriously tunneled, while the interior of
these timbers remained uninfested. This condition results from a high proportion of
heartwood being found in construction lumber used in houses built earlier in this century.
Heartwood contains extractives that repel many insects (Miller 1987) so H. gibbicollis larvae
were usually found within the sapwood portion of timbers. In certain instances, larvae would
tunnel in heartwood, generally when the sapwood had been depleted. Two other wood-
infesting anobiids, Anobium punctatum (De Geer) and E. peltata, are also predominantly
found in sapwood because it is higher in carbohydrates and nitrogen (Becker 1942, Bletchly
and Farmer 1959, Williams and Mauldin 1981).
Characteristics of Infested Structures.
Many houses are now built with central heating and air conditioning units which lower the
RH and wood moisture content below the threshold necessary for anobiid survival.
However, the air-tight conditions found in some new buildings can also lead to wood
moisture levels that encourage beetle attack. Relative humidity levels within western
Washington substructures ranged from 47 to 95%, the average value being 69.7%. Clothes
dryers vented into crawl spaces increased RH within the enclosed area and plumbing leaks
may also lead to moisture-related insect problems. Improper placement of vents, inadequate
ventilation, or obstructed air flow caused by excessive vegetation or debris can produce high
wood moisture content, even in well built houses. In this study only 40% of houses had
adequate vents (0.09 m? vent surface:13.80 m2 crawl space area, minimally required) and
55% of those houses had vents which were obstructed in some way. Dead air spaces,
resulting from little or no air movement within substructures, often result in areas of high
wood moisture content.
Table 3
Wood moisture data from eastern Washington simulated crawl space.
Treatment Wood moisture range (%) x + SEM
VBaeV] 10 - 19 192
VB 8 - 18 14.9 + 0.44
NONE 10 - 22 17.2 0,4"
Means followed by the same letter do not differ significantly (P = 0.05) based on r tests (SAS Institute
1985). |
1 V = vent; VB = vapor barrier; NONE = neither treatment.
Table 4 }
Construction dates of structures! infested with Hemicoelus gibbicollis.
Date structure built No. of structures % of structures
pre- 1900 ) 6.3
1900-19 24 30.4
1920-39 | 34.2
1940-59 16 203
1960-79 5 6.3
after 1979 2 2
‘total of 79 structures, data unavailable for remaining II buildings.
68 J. ENTOMOL. Soc. Brit. COLUMBIA 89, DECEMBER, 1992
60
ae haha, Ni
aN /
s |
“>” V |]
* 8 jhe
me 5@ ee a e od #0 8
— Oe Ce: Ago 4 wi woO
RP we om 0; Te) ® a, BEODOOS, (|
a 45 e e on Li Ot aac
o © O00 On Oman |. i
© o w i
ss © és 48
ES 40 Home
<< emo
a 6 6
re H
Ae
Ze Oo No Vapor Barrier or Vent
YO
« Vapor Barrier, No Vent
© Vapor Barrier and Vent
A
Sore Eel f eee
7/89 1/90 7/90 1/91 C/O
Figure 2a. Relative humidity in simulated crawl space with three partitioned compartments; eastern
Washington.
50 re
© No Vapor Barrier or Vent
a Vapor Barrier, No Vent
© Vapor Barrier and Vent
40
RELATIVE HUMIDITY (%)
50
25 ee
7/90 11/90 3/91 7/91 11/91
Figure 2b. Relative humidity in simulated crawl space with three partitioned compartments; western
Washington.
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 69
Excessive wood moisture can be dependent on conditions created outside of the
substructure. Contact between wood and soil was common in many houses. Moss or other
organic debris on the roof often leads to improper water runoff. Non-functioning gutters may
direct water into the crawl space or basement, thus increasing wood moisture content.
Improper soil grade is a major contributor to increased water being found in lower levels of
buildings. Greater than half of the structures in this study had inadequate gutters or soil
grade which resulted in standing water in the substructure.
Barns and outbuildings are often seriously infested by H. gibbicollis. These unheated
structures present ideal conditions for larval development. Often these outbuildings are
continually reinfested until nothing remains but frass and a thin shell of wood. They can then
serve as a source of infestation for other main structures. One house was examined that had
an unheated, open attic area where conditions were similar to those in a barn. Hemicoelus
gibbicollis was very active in this structure, infesting not only the ceiling and floor, but also
maple and oak furniture stored in the attic. No larval activity was noted in the second floor
area beneath the attic, most likely because the wood moisture content was 11-12%. In coastal
areas of western Norway, Knudsen (1968) found that A. punctatum infested attics and craw!
spaces equally.
Wood moisture content, being influenced by RH, is probably the major factor allowing
anobiid infestations to develop. Structures located close to bodies of water often had higher
than usual wood moisture content and more extensive damage (Suomi, unpublished
observations). Clay and other heavy soils that retain water may also contribute to increased
wood moisture within a substructure, especially if these soils are not covered with a vapor
barrier. Temperature has a limited effect because it influences the amount of moisture
remaining in air surrounding wooden timbers (Miller 1987). The average temperature during
summer months in western Washington crawl spaces examined in this study was 16.6°C and
ranged from 10 to 22°C. Hemicoelus gibbicollis is normally found in mild climates where
temperature extremes are encountered infrequently. Photoperiod does not appear to have any
role in the development of this insect because relatively low, unchanging light levels are
normally found within timbers in most crawl spaces. Suomi (1992) showed that H.
gibbicollis larvae remained active and continued feeding throughout the year, thus demon-
strating that time of season does not influence larval activity.
Populations of anobiid larvae present in structural timbers can be reduced, and eventually
eliminated, by controlling wood moisture content. One inexpensive method is to cover the
entire crawl space floor with a 4-6 mil vapor barrier. Wooden debris and any construction
lumber unnecessary to structural support should be removed. Adequate, unobstructed
ventilation must be provided for free air movement. Buildings located near the ocean,
despite all necessary precautions having been taken, were still found to have wood moisture
levels of 14-15% and so remained at risk from beetle infestations. Knudsen (1968) noted that
frequency of attacks by A. punctatum decreased as distances from coastal areas increased.
This was also found to be true of H. gibbicollis.
ACKNOWLEDGEMENTS
The authors thank Jan and Red Butler of Angeles Pest Control, Sequim, WA, Terry
Whitworth of Whitworth Pest Control, Tacoma, WA, and the many other PCOs who
donated their time to assist in our search for anobiid-infested structures. A special thanks is
extended to Brian Raynes for assisting in data collection in some very unpleasant crawl
spaces and to Dr. Art Antonelli for temperature and RH data collection at the western
Washington research site. We also thank Liz Myhre for help with the drawing.
REFERENCES
Becker, G. 1942. Okologische und physiologische untersuchungen iiber die holzzerst6renden larven von Anobium
punctatum Deg. Z. Morph. Okol. Tiere 39: 98-151.
Berry, R. W. 1976. Laboratory rearing of Anobium punctatum. Mater. Org. Il: 171-182.
Bletchly, J. D. and R. H. Farmer. 1959. Some investigations into the susceptibility of Corsican and Scots pines and
of European oak to attack by the common furniture beetle, Anobium punctatum DeGeer (Col., Anobiidae). J.
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Chamberlin, W. J. 1949. Insects Affecting Forest Products and Other Materials. Oregon State College Coop.
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Doane, R. W., E. C. Van Dyke, W. J. Chamberlin, and H. E. Burke. 1936. Forest Insects. McGraw Hill, New York.
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Furniss, R. L. and V. M. Carolin. 1977. Western Forest Insects. USDA For. Serv. Misc. Pub. 1339. 654 p.
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Hickin, N. E. 1981. The Woodworm Problem. 3rd ed. Hutchinson, London. 123 p.
Knudsen, P. 1968. Distribution and abundance of Hylotrupes bajulus (L.) (Col., Cerambycidae) and Anobium
punctatum (de Geer) (Col., Anobiidae) along the Sognefjord in West Norway. Rev. Appl. Entomol. A: 188-189.
Knutson, L. V. 1963. Revision of the genus Hadrobregmus of North America (Coleoptera: Anobiidae). Proc.
Entomol. Soc. Wash. 65(3): 177-195.
Linsley, E. G. 1943. The recognition and control of deathwatch, powderpost, and false powderpost beetles. Pests
IL: 11-14.
Mampe. C. D. 1982. Wood-boring, book-boring, and related beetles, pp. 276-309. In A. Mallis (ed.), Handbook of
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Miller, R. B. 1987. Structure of wood, pp. 2.2-2.5. In M. Davidson and A. Freas (eds. ), Wood Handbook: Wood as
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Suomi, D. A. 1992. Biology and management of the structure-infesting beetle, Hemicoelus gibbicollis (LeConte)
(Coleoptera: Anobiidae). Ph.D. dissertation, Washington State Univ., Pullman. 166 p.
Williams, L. H. and H. M. Barnes. 1979. How Xyletinus peltatus beetles affect strength of southern pine joists.
Environ. Entomol. 8(2): 304-306.
Williams, L. H. and J. K. Mauldin. 1981. Survival and growth of the anobiid beetle, Xyletinus peltatus (Coleoptera:
Anobiidae), on various woods. Can. Entomol. 113: 651-657.
Williams, L. H. and R. V. Smythe. 1978. Wood-destroying beetle treatment incidence in Arkansas and Georgia
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Williams. L. H., H. M. Barnes, and H. O. Yates, HJ. 1979. Beetle, (Xvletinus peltatus) and parasite exit hole
densities and beetle larval populations in southern pine floor joists. Environ. Entomol. 8(2): 300-303.
J. ENTOMOL. Soc. BRIT. COLUMBIA 89, DECEMBER, 1992 71
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Journal
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Volume 89 Issued December 1992 ISSN #0071-0733
Directors of the Entomological Society of British Columbia, 1992—93
Blacker, N.C. Some ants (Hymenoptera: Formicidae) from
Southern Vancouver Island, British Columbia
Lindgren, B. Staffan. Attraction of Douglas-fir beetle, spruce beetle and a |
bark beetle predator (Coleoptera: Scolytidae and Cleridae) to
enantiomers of frontalin
Cossentine, J.E. and L.B. Jensen. Establishment of Phyllonorycter mespilella
(Hiibner) (Lepidoptera:Gracillariidae) and its parasitoid, Pnigalio flavipes
(Hymenoptera:Eulophidae), in fruit orchards in the Okanagan and
Similkameen Valleys of British Columbia
Toba, H.H. and J.D. Campbell. Wireworm (Coleoptera: Elateridae) survey in
wheat-growing areas of northcentral and northeastern Oregon
Baird, Craig R., Keith W. Dorschner, and Carolyn J. Nyberg. Biology of the black
vine weevil Otiorhynchus sulcatus on hop in Idaho (Coleoptera: Curculionidae)
Scudder, G.G.E. The distribution and life cycle of Reduvius personatus (L.)
(Hemiptera: Reduviidae) in Canada
McIntosh, R.L. and J.A. McLean. A life stage development index for 7rypodendron
lineatum (Oliv.) in a spruce boom on the Alberni Canal, Vancouver Island
Lam, Desmond K.W., and John A. McLean. Seasonal abundance and distribution of
ambrosia beetles on the North Arm of the Fraser River, British Columbia
W.R. Jacobi. Potential insect vectors of the black stain root disease pathogen
on Southern Vancouver Island
Suomi, Daniel A. and Roger D. Akre. Distribution of economically important,
wood-infesting anobiid beetles in the Pacific Northwest
Suomi, Daniel A. and Roger D. Akre. Characteristics of structures attacked by the
wood-infesting beetle, Hemicoelus gibbicollis (Coleoptera: Anobiidae)
NOTICE TO CONTRIBUTORS
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{61
a Journal
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Volume 90 Issued December 1993 ISSN #0071-0733
Se eet eee Society
COVER: Male Cybaeus multnoma Chamberlin and Ivie (Araneae, Cybaeidae) drawn by Robb _
Bennett. Scale bar = 2 mm. Individuals of about two dozen species of this Holarctic genus are
dominant generalist predators in the forest floor arthropod community of the Pacific Northwest
especially in coastal regions. Six species are known to occur in British Columbia. Cybaeus
reticulatus Simon and C. morosus Simon are abundant in a variety of coastal habitats from San —
Francisco to the outer Aleutian Islands (in the Queen Charlotte Islands the former is found from
sea level wet forests to alpine meadows). Cybaeus signifer Simon and C. eutypus Ch. and Ivie
are very cor mon in south eastern B.C. They range from mid-coastal B.C. south to Big Sur and
the Yosemite area (C. signifer) and from the Queen Charlotte Islands to mid-coastal Oregon and
the Willamette Valley (C. eutypus). Two other species have more restricted ranges: C. sinuosus
Fox is apparently endemic to the Canadian Rockies in Banff, Jasper, and Yoho National Parks
and a new species is found in south central B.C. and adjacent Washington from Lillooet through
the Okanagan Valley to Okanogan County. Many species of Cybaeus (most notably in Japan,
California, and Oregon) have extremely restricted ranges and are known from only a few spec-
imens. From: Bennett, R.G. 1991. The systematics of the North American cybaeid spiders
(Araneae, Dictynoidea, Cybaeidae). Ph.D. dissertation, Univ. of Guelph, 308 pp.
Designed and typeset by the Graphics Group
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Text printed on 60 Ib. Halopaque Vellum Recycled Paper.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 1
Journal
of the
Entomological Society
of British Columbia
Volume 90 Issued December 1993 ISSN #007 1-0733
Directors of the Entomological Society of British Columbia, 1993-94 ooo... ccccesesscceseeeeceeeeseeeneeees py
Vernon, R.S. and D. Thomson. Effects of soil type and moisture on emergence of tuber flea beetles,
Epurix luberis (Coleoptera: Chrysomelidae) from potato fields .............:c..ccseccsecessssecssecessetercscenneses 3
Gray, T. and R. Shepherd. Hymenopterous parasites of the blackheaded budworm,
Acleris gloverana on Vancouver Island, British Columbia, 1970-1974 o......cccccccsccesseeeeceesecesseeenees 1]
Gray, T.G. and G. Gries. Sex pheromone components of an undescribed Choristoneura species
(Lepidoptera: Tortricidae) on lodgepole pine in British Columbia..................:..s:..scsscesecsssccssccsreseees 13
Li, S.Y. and D.E. Henderson. Response of Trichogramma sp. nr. sibericum
(Hymenoptera: Trichogrammatidae) to age and density of its natural hosts,
the'eges of Rhopobota naevana (Lepidoptera: Tortricidae) .......:.ciescsscsssssesestesecneacessccssssosesocranssonesess 18
Alfaro, R.I., M. Hulme and C. Ying. Variation in attack by Sitka spruce weevil,
Pissodes strobi (Peck), within a resistant provenance Of Sitka SPruce ...........c.ccesssseesecsteeeeeesseseeeeeens 24
MacLauchlan, L.E., J.H. Borden and I. Price. Life history and pheromone response in
iissodes schwarzt Hopk. (Coleoptera: Curculionidac).......:........sssescssecssaccesstscncseosssenseoncessetssnccosencens 30
Clements, S.J., M.E. Bernard and D.A. Raworth. A versatile wind-resistant insect Cage.........ceeeeeee £5)
Schaber, B.D., J.F. Dormaar and T. Entz. Effect of burning alfalfa stubble
HOM Se Cae Sb CONULOL Ol SECC VIEIC ...2..:.s4nscrsecoesasusdeonztoeesnatsyosestadnsesadeoesteadeavanecedsnanezevondvecswadlonagdaesanedes 4]
Strong, W.B. and B.A. Croft. Phytoseiid mites associated with spider mites on hops
MERC EVN luacuinae (OV ALLEY, AOTC BOM witsss sessed ears sha aca veioae cusseastelac aucoleees cisanc@eseeonenteciuasattcvantua weeseen tana tes 45
Safranyik, L. and D.A. Linton. Relationships between catches in flight and emergence
traps of the mountain pine beetle, Dendroctonus ponderosae Hopk. (Col.: Scolytidae) ................ mis)
Li, S.Y., G. Sirois, D.L. Lee, C. Maurice and D.E. Henderson.
Effects of female mating status and age on fecudity, longevity and sex ratio in
Trichogramma minutum (Hymenoptera: Trichogrammatidae) ...........ccccecsccessececeeteceseeceeeeeeeenseeeeaes 61
Harper, A.M., B.D. Schaber, T. Entz and T.P. Story. Assessment of sweepnet and
suction sampling for evaluating pest insect populations in hay alfalfa... eee ecseeeeteeteeeeeteeeees 66
Chan, C.K. and B.D. Frazer. The aphids (Homoptera: Aphididae) of British Columbia ..............ccceceseeeees 77
NOTE
Campbell, JM. and N.N. Winchester. First Record of Pseudohaida rothi Hatch
(Coleoptera: Staphylinidae: Omalinac) from Canada .i.2...c.2c.00csecsesessascessaancsercasonsssasonseassaseuessenssesebagecsnaczes 83
Eieatavonvolume. so, Deceinber 1992. ex o.afade cs aseseasneiatleees gudie os clea sbubevautuadsdaatdotiastovessvannieesdacstibecedmacasesuses 84
INO MIC EO CONTRIB U TORS vs. cocs cosas iiss has cts heats tata cenacccetvaadeusstecoeorsane inside back cover
J. ENTOMOL. Soc. Brit. COLUMBIA 90, DECEMBER, 1993
DIRECTORS OF THE ENTOMOLOGICAL SOCIETY
OF BRITISH COLUMBIA FOR 1993-94
President
Sheila Fitzpatrick
Agriculture Canada, Vancouver
President-Elect
Linda Gilkeson
B.C. Ministry of Environment, Victoria
Past-President
Terry Shore
PEC, Victoria
Secretary
Sharon Clements
Agriculture Canada, Vancouver
Treasurer
Shiyou Li
Agriculture Canada, Vancouver
Editorial Committee (Journal)
Richard Ring (Editor) H.R.MacCarthy Peter Belton
Editor (Boreus)
Elspeth Belton
S.EU.
Directors
R. Bennett (2nd) A.Chow (2nd) _ S. Lindgren (2nd)
K. Naumann (Ist) L. Poirier (1st)
Honorary Auditor
Bob Vernon
Agriculture Canada, Vancouver
Regional Director of National Society
Terry Shore
PFC, Victoria
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 3
Effects of soil type and moisture on emergence of tuber flea
beetles, Epitrix Tuberis (Coleoptera: Chrysomelidae)
from potato fields
ROBERT S. VERNON
AGRICULTURE CANADA, RESEARCH STATION, VANCOUVER, BRITISH COLUMBIA,
CANADA V6T 1X2
DONALD THOMSON
AGRICULTURE CANADA, RESEARCH STATION, SUMMERLAND, BRITISH COLUMBIA,
CANADA V0H 1Z0
ABSTRACT
The numbers of adult tuber flea beetles, Epitrix tuberis Gentner, emerging from different soil
types in the lower Fraser Valley of British Columbia were compared in 1987 and 1988. Over-
wintered beetles (P1) were released at known densities onto caged Russet Burbank potato plants
grown in soils with different inorganic, organic, and moisture characteristics. The time from the
introduction of P1 beetles in June to the mean initial emergence of first generation (F1) beetles
ranged from 38 to 47.2 days during the two years of study. The female:male sex ratio of 2210
F1 beetles was 1:0.94, with a slight but significant bias in females early in the emergence period.
Although significantly more F1 beetles emerged from some highly organic soils than from some
mineral soils in both years, inorganic, organic and moisture factors of the test sites did not cor-
relate consistently with the emergence of F1 beetles in time or numbers. Fl emergence from
mineral soils was never significantly greater than that from highly organic soils. This work in-
dicates that the economic injury level derived from studies of P1 beetles in highly organic soils
could be applied to other soil types with minimal risk to potato crops.
INTRODUCTION
The tuber flea beetle, Epitrix tuberis Gentner, is a serious pest of potatoes grown commer-
cially and domestically in the lower Fraser Valley of British Columbia. Adults overwinter in soil
in and around potato fields (Vernon and Thomson 1991) and emerge from mid-May to early
June. Although they are polyphagous, overwintered tuber flea beetles prefer to feed and oviposit
on potato plants (Finlayson 1950), and in particular on late season varieties such as Russet Bur-
bank. Oviposition by overwintered beetles (P1) occurs from late May to early July. The result-
ing first larval generation (F1) feeds on the seed pieces and developing roots of young potato
plants, but generally causes little or no economic damage at this stage (Giles 1987). The ensu-
ing F1 summer adults produce the second larval generation (F2) from mid-July through August
when tubers are maturing. Feeding by F2 larvae results in tuber deformations, in surface chan-
nels and in sub-surface tunnelling that can seriously lower crop marketability.
To avoid damage from flea beetles, growers often apply sprays on a 7-10 day schedule, be-
ginning at crop emergence. This can amount to as many as 10 sprays per season. To improve
timing and thereby reduce the number of sprays, visual and sweep-net monitoring programs for
adults of the Pl and F1 generations were developed (Vernon et al. 1990; Cusson et al. 1990) and
are available to producers through commercially operated integrated pest management (IPM)
programs. A major objective of these IPM programs is to improve control of the P1 adult gen-
eration so that spraying against the later Fl adults is not needed. By not having to spray F1
adults, mechanical plant damage and soil compaction caused by spray machinery is reduced,
and the build-up of natural parasites and predators of aphids is augmented during the critical pe-
riod of aphid outbreak in July and August.
Giles (1987) proposed that maintaining P1 beetles below 0.05 beetles per row- metre of pota-
toes would prevent economic damage to tubers from occurring without the need for F1 beetle
sprays. This action threshold has been in use in potato IPM programs since 1988, and it has gen-
4 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
erally been found that P1 adults can be maintained below the action threshold with one or no
sprays. Using sweep-net monitoring of F1 beetles as a backup, and a mean action threshold of
one F1 beetle per sample of 10 sweeps (Anon. 1991), economic tuber damage has not occurred
in any of the 700 fields monitored since 1988 (R.S. Vernon, unpublished data).
Giles’ (1987) P1 action threshold was derived from research conducted near Cloverdale, a
vegetable growing area of the lower Fraser Valley with soil high in organic matter and moisture.
Population growth of the closely related potato flea beetle, E. cucumeris (Harris), was found to
be greatly affected by differences in soil type and soil moisture (Daniels 1933; Hoerner and
Gillette 1928). Their observations suggest that the P1 action threshold developed for E. tuberis
may also vary depending on soil moisture, temperature and soil type. The question is important,
since most potatoes in B.C. are grown in mineral soils low in organic matter and water-holding
capacity, and monitoring programs that employ Giles’ P1 action threshold are rapidly expand-
ing into these areas.
This study was initiated to assess the effect of soil type and irrigation on E. tuberis popula-
tions from the P1 adult to the F1 adult generations. The importance of these findings for imple-
menting and improving monitoring programs for E. tuberis in other potato growing areas of
British Columbia is discussed.
MATERIALS AND METHODS
Emergence Cages: Pyramidal emergence cages, modified from Giles (1987), were con-
structed from 1.3 cm thick plywood, with a 46 x 105 cm open base tapering to a 5 x 5 cm flat
top, and 35 cm in height. A 0.7 cm diam hole was drilled in the center of the cage top, and a clear
plastic tygon tube (0.7 cm diameter by 4 cm long) pushed 1 cm into the plywood. Small clear
plastic vials with a hole drilled in the cap were inserted cap down over the tubing to collect
emerging beetles orienting upwards against gravity and towards the light. To ensure that light
was entering the cages only from the hole at the top, all joints were sealed with fibreglass from
the inside, and painted black.
Two experiments were done to determine the efficiency of the cages in collecting known
numbers of beetles. Six cages were placed over bare ground, and the bases covered with soil.
Twenty E. tuberis adults were collected and dropped through the top of each cage on 3 and 22
August, 1988. Beetles trapped in the vials atop each cage were counted for 2 days following
each release.
Emergence Studies: Experiments were conducted in 1987 and 1988 to examine the effects
of the inorganic, organic, and moisture characteristics of soil on the population growth of E. tu-
beris in commercial potato fields. Population increase was measured by caging known numbers
of P1 adults for fixed intervals on plants in different soil types, and quantifying the subsequent
emergence of F1 beetles over time using the emergence cages described. This approach gave an
estimate of comparative habitat suitability for E. tuberis populations.
1987: The plantings of potato were established at three different sites in the lower Fraser Val-
ley: at Abbotsford in an orthic humo ferric podzol; at Cloverdale in a highly organic peaty
gleysol; and at Delta in a rego gleysol. The methods used to characterize the inorganic and or-
ganic fractions of each soil are described by McKeague (1976), and the physical characteristics
of each soil are listed in Table 1. At each location, the soil was rotovated to a depth of 30 cm be-
fore planting. Whole tubers (cv. Russet Burbank) of uniform size were planted in pairs at a
depth of 15 cm, with 30 cm between the pair of plants. A minimum of | m separated adjacent
pairs. Seeding was done on 20, 21 and 25 May at the three sites, respectively, and all the plants
were hilled once before emergence. Shortly after emergence, each pair of plants was enclosed
in a wood-framed screen (.04 cm mesh) cage (80 x 69 x 63 cm) to prevent outside infestation
by wild E. tuberis. Since wild E. tuberis typically infest potato fields along the outermost rows
(Cusson et al. 1990), plots in both the 1987 and 1988 studies were located well inside commer-
cial fields of potatoes to further reduce the threat of natural infestation.
The caged plants were infested with E. tuberis collected from a holding plot near the Ab-
botsford site. The holding plot consisted of a 0.04 ha planting of potatoes (cv. Russet Burbank)
that was infested between | and 15 June with more than 10,000 beetles collected from backyard
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 5
gardens in Abbotsford. For release into each cage, a given number of mating pairs of beetles
were aspirated from plants, placed into individual 10 cm lengths of tygon tubing and trans-
ported in coolers on the same day, to the three sites. Five mating pairs were released into each
cage at each site on 19 June, and a further two mating pairs were added on 22 June. The cages
were removed on 29 June, and the surviving beetles on each plant pair collected with aspirators
over a period of 2 days. By 30 June, 78%, 70%, and 61% of the beetles at Abbotsford,
Cloverdale and Delta, respectively, had been recaptured. Visual inspections of the exposed
plants conducted each week between 2 and 24 July confirmed that reinfestation from outside the
plots did not occur.
Beginning on 2 July at all sites, the uncovered paired plants were allocated watering regimes:
1) no watering (control plots); 2) 10 L water once every 2 weeks; 3) 10 L water once per week
and; 4) 10 L water twice per week. At Abbotsford and Cloverdale, five and four replicates, re-
spectively, of all watering regimes were used. At Delta, four replicates each of watering regimes
1,2 and 3 were used. Watering was stopped on 23 July. The watering regimes (treatments) were
arranged in randomized complete blocks at each site.
To prevent run-off of water, soil dykes were made (46 by 105 cm) around each pair of plants.
Water was applied evenly inside the dykes with a watering can on Mondays (watering regimes
2, 3 and 4) and Thursdays (watering regime 4). Soil moisture samples (cores 2 cm diameter by
15 cm deep) were taken from between each pair of plants every Wednesday from 2-22 July.
Each soil sample was weighed, dried in an oven, and the percent moisture content by weight de-
termined.
On 24 July, the plants in each treatment were cut off just below soil level and the dyked area
cleared of plant debris. Emergence cages were placed over the area where the plants had been
removed, and the bases of the cages sealed with soil. The cages were examined for emerged bee-
tles daily from 25 July until emergence had declined to one beetle per cage per day. At the
Cloverdale and Delta sites, beetles emerging daily from each irrigation treatment were retained
and their sex determined in the laboratory.
1988: The effect of soil type and moisture on tuber flea beetle emergence was further stud-
ied at 9 locations in the lower Fraser Valley. The characteristics of the soils at each location are
listed in Table 2. On 9 June, all plots were prepared and planted as described for the 1987 study.
On 22 June, ten mating pairs of beetles were collected from a new holding plot at Abbotsford
and released into each of 5 or 6 cages at each site (Table 2). The cages were removed on | July,
and the surviving beetles on each plant collected by aspiration during the next 2 days. An aver-
age of 65% of the beetles released had been collected from the plants (range = 57-81%) by 2
July. Visual inspections of the exposed plants were conducted each week between 2 and 28
July, which confirmed that reinfestation from outside the plots did not occur. On 28 July, emer-
gence cages were installed, and the cages were examined for emerged beetles daily from 29 July
until emergence at each site had declined to one beetle per cage per day.Seven of the 9 locations
were chosen to provide a wide range of values of percent organic matter in the soil. At each lo-
cation, mean daily air temperatures from the time of P1 release to the end of the Fl emergence
were recorded using electronic hygrothermographs (Datapods, Model DP220, Omnidata Inter-
national, Inc., Logan Utah) placed at ground level in Stevenson screens.
Two of the nine study locations were used to assess the effects of continuous irrigation on E.
tuberis emergence (Table 2). Two adjacent rows of potatoes, 10 m long, were planted 4 m apart
on 9 June. Potatoes in each row were planted in six pairs, with 30 cm between each paired plant,
and 1.5 m between consecutive pairs. Each pair of plants was caged, and 10 mating pairs of bee-
tles introduced to each cage. After beetle removal on | July, a perforated soaking hose was in-
stalled 2 cm below the surface, 30 cm along the north and south sides of plants in the northern-
most potato row. Water was delivered continuously for the next 20 days so that the ground was
visibly moist but not flooded. Soil samples were taken every 3-4 days from between each potato
pair at all 9 locations in the study from 2-22 July, and their moisture content determined.
Statistical Analysis
Temporal Emergence Patterns: The number of days between the initial release of P1 bee-
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
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J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 q
tles and the mean initial and 50% emergence of F1 beetles was determined for each study site
and for every watering regime. Mean days to initial and 50% emergence, both within and be-
tween study sites for each year, were compared by ANOVA, and Duncan’s (1955) multiple
range test. Mean daily air temperature in 1988 from the time of P1 release to the mean initial and
50% emergence of the F1 adult generation, respectively, were regressed on time to initial F1
emergence at each study site to investigate the effect of temperature on the rate of development
of E. tuberis.
Sex Ratio at Emergence: Beetles emerging from each watering treatment at the Cloverdale
and Delta sites in 1987 were grouped into 4 emergence periods. The first 3 periods were 5 days
long and the last was 12 days. The effects of site, treatment and emergence period on the sex ra-
tio of the emerging beetles were tested by analysis of Chi-square using the SAS procedure CAT-
MOD (Grizzle et al. 1969). In this analysis, emergence period was treated as a continuous vari-
able.
Effect of Soil Type and Moisture on Emergence: To facilitate comparisons between the
two years, the numbers of F1 beetles emerging from soil into cages in each year were stan-
dardized by dividing the mean emergence per plot by the number of P1 female oviposition days
per plot in each study. P1 female oviposition days were determined by multiplying the number
of females released per plot by the number of days between release and recapture. The number
of F1 beetles emerging per P1 female per plot per day of oviposition is referred to as the “F1 pro-
duction’. Differences in total Fl production between and within sites for each year were ex-
amined by ANOVA after log10 transformation. Differences in emergence were ranked using
Duncan’s multiple range test. A significance level of P < 0.05 was used throughout .
RESULTS AND DISCUSSION
Efficiency of Emergence cages: Numbers of beetles emerging from cages in the 3 Aug. re-
lease recapture study (85.8% recapture) were not significantly different from the 22 Aug. study
(83.3% recapture), so the results were combined. Of twenty beetles released into each of 12
cages, an average of 16.2 beetles were recaptured on the first day after release (range = 13-20
beetles) and 0.8 beetles on the second day (range = 0-2 beetles). The average recapture per cage
was 16.9 beetles (range = 14-20 beetles), or 84.6% of the 240 beetles released. Although a
100% recapture rate by the emergence cages was not a prerequisite for their use in the other
emergence studies reported here, these results do show that the emergence cages would proba-
bly underestimate the absolute number of beetles emerging from the soil.
Temporal Emergence Patterns: Among unwatered plots at the three study sites in 1987,
significant differences were observed in the time from P1 beetle release to mean initial emer-
gence (F = 6.24; df = 4,2; P = 0.034), or 50% emergence (F = 7.12; df = 4,2; P = 0.026) of F1
beetles (Table 1). Initial and 50% F1 emergence were at least 4 days earlier in Delta than in Ab-
botsford or Cloverdale. Differences in initial or 50% emergence among watering regimes at any
of the three sites were not statistically significant.
In the 1988 soil type study, significant differences were observed in the time from P1 beetle
release to mean initial emergence (F = 21.54; df = 4,6; P= 0.0001), or 50% emergence (F = 19.9;
df = 4,6; P=0.0001) of F1 beetles between sites (Table 2). Mean initial emergence ranged from
38.0 days (site 4) to 45.2 days (site 7). Finlayson (1950) recorded a 42 day period from egg to
initial Fl emergence, and a 39 day interval from egg to F2 emergence of E. tuberis in the inte-
rior of British Columbia.
Temperature affected the length of time from egg to adult of FE. cucumeris in an insectary (Hill
and Tate 1942). This may also explain the differences in the time from egg to adult occurring
between sites in our studies. The regression of days to mean initial emergence on mean air tem-
perature during that time (independent variable) for the 7 sites in the soil texture study of 1988,
indicated that development time decreased with an increase in mean air temperature (y = 183.18
- 8.545x; r= 0.68; P = .02). A similar trend was observed for mean development time to 50%
emergence regressed on mean air temperature (y = 147.97 - 6.005x; r’= 0.65; P = .03). The re-
sults suggest that a more comprehensive day-degree model based on air temperatures could be
developed to help predict the time of emergence of F1 beetles. The regression model for initial
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
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J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 9
emergence, however, is presently limited to the narrow range of mean temperatures encountered
during the development period in 1988 (i.e. 16.4-16.9 degrees C). Since temperatures in June
and July of 1988 were near the 30 year average for the Fraser Valley, the predictability of the
model for mean air temperatures above or below the range of temperatures tested in 1988 would
have to be determined with further research. This would be worthwhile, since air temperatures
in many B.C. potato fields are already being recorded using Datapods for the prediction of
potato late blight, Phytophthora infestans (De Bary).
In the absence of a comprehensive day-degree or regression model, existing EF. tuberis mon-
itoring programs could be immediately improved by ensuring that high risk fields are monitored
more intensively for F1 beetles beginning no later than 38 days (the earliest development inter-
val recorded in 1987 and 1988) following the initial detection of P1 beetles. In seasons where
mean temperatures are above normal, monitoring should begin earlier than 38 days at the dis-
cretion of the consultants. Since F1 females have a pre-oviposition period of 6 days (Finlayson
1950), early detection of above threshold F1 beetles would allow growers to withold sprays up
to 5 or 6 days, allowing time for additional emergence to occur to maximize the efficacy of
sprays.
Sex Ratio at Emergence: The sex of 510, 889, 483 and 328 beetles was determined, re-
spectively, for 4 consecutive emergence periods from the Delta and Cloverdale sites in 1987.
The analysis of chi-square indicated that the sex ratio differed significantly (P = 0.03) between
sites. The female:male sex ratios of F1 beetles emerging from the site in Delta (n = 801 beetles)
and Cloverdale (n = 1409 beetles) were, respectively, 1:1.01 and 1:0.90. The percentage of fe-
males emerging (i.e. 53.3, 52.8, 49.9 and 48.2%) over the 4 emergence periods decreased
slightly but significantly (p = 0.04) with time of emergence. Finlayson (1950), observed a 1:1
sex ratio in P1 beetles emerging from hibernation, but did not determine the sex ratio of F1 bee-
tles emerging over time.
Effect of Soil Type and Moisture on Emergence: Watering regimes at various intervals in
1987 did not significantly affect beetle emergence at any of the three sites (Table 1). The aver-
age water content at each site was raised only slightly (Table 1), even in the most heavily wa-
tered treatments. Irrigating the soil continuously following the oviposition period in 1988 did
significantly (F = 162.8; df = 3,1; P = .001) increase the soil moisture content (Table 2), but the
effect on emergence was not significant (F = 3.48; df =1,5; P = 0.12). Because watering began
after beetles were removed from the plots in both years, the eggs that were layed during the
Oviposition period would have largely preceded the watering schedule. The egg stage of EF. tu-
beris has a mean incubation period of 5.5 days (range 3-14 days, Hill and Tate, 1942). Water-
ing, therefore, would have coincided more with the succeeding larval and pupal stages of E. tu-
beris in this study.
In the unwatered treatments in 1987, significantly more beetles emerged from the Cloverdale
site than from the Abbotsford site, but not from the Delta site (F = 6.01; df = 4,2; P = 0.037)
(Table 1). In the soil type study of 1988, significant differences (F = 6.46; df = 6,4; P = 0.0004)
in emergence also occurred, with sites 4 and 5 having significantly more emergence than sites
1 and 3 (Table 2). Differences in F1 production between the Cloverdale and Abbotsford sites
were more pronounced in 1987 (Table 1) than in 1988 (Table 2). Fl production was lower in
1987 than in 1988 in the Abbotsford soils, and higher in 1987 than in 1988 in the Cloverdale
soils.
The significant differences observed in F1 production between certain sites in 1987 and 1988,
can be attributed to biotic or abiotic effects on E. tuberis adult vigour, oviposition, or on the sur-
vival of immature stages in the soil. The amount of oviposition by many soil-ovipositing bee-
tles is directly related to the texture and moisture content of the soil (Gaylor and Frankie 1979;
Marrone and Stinner 1983a; Brust and House 1990). These variables also affect egg and larval
survivorship in some beetle species (Gaylor and Frankie 1979; Marrone and Stinner 1983b).
Generally, oviposition and subsequent survival of eggs and larvae are promoted in moist, or-
ganic soils. Organic matter and water content were highly correlated in our 1988 study (Pear-
son correlation coefficient = 0.954, P < .0002), but neither of these variables was significantly
correlated with the production of F1 E. tuberis. Of the inorganic soil components, only clay was
10 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
significantly correlated (Pearson correlation coefficient = 0.810, P < 0.02) with the emergence
of F1 E. tuberis in unwatered sites in 1988. Emergence in soils with less than 10% clay varied
widely, however, (Table 2) making this relationship of little practical importance. The results
from both years do show that F1 production from mineral soils was never significantly higher
than from the organic soils. The reason, or reasons for the greater F1 production observed in cer-
tain Cloverdale soils, however, could not be determined from this study.
Soil Type and Action Thresholds
Giles (1987), working with a peaty gleysol (61.4% organic matter), proposed that maintain-
ing P1 E. tuberis at levels below 0.05 P1 beetles per metre of row would keep numbers of F2
larvae below an economic damage level. Until now, this action threshold was valid only for E.
tuberis monitoring programs conducted in regions of the Cloverdale area with similar, highly
organic muck soils. The results reported here indicate that the P1 action threshold developed for
the peaty gleysol of Cloverdale could also be used in potato growing areas with different soil
types, such as Delta and Abbotsford, without risk to potato crops. This is because the same
number of P1 beetles occurring on plants grown in Delta or Abbotsford would ultimately give
rise to equal or fewer F1 adults than would the same number of P1 beetles on plants grown in
Cloverdale. Since the F1 action threshold of 1 beetle per 10 sweeps is recommended for moni-
toring programs in any soil type (Anon. 1991), the use of Giles P1 action threshold in a mineral
soil should not increase the need for F1 sprays.
ACKNOWLEDGMENTS
We thank J. Hall for statistical analysis and review, J. R. Mackenzie, K. Telford and K. Har-
riot for technical assistance, and H. R. MacCarthy, B. D. Frazer, and M. Cusson for review of
the manuscript. We especially thank the Agri-Food Regional Development Subsidiary Agree-
ment (A.R.D.S.A.) for support funding.
REFERENCES
Anonymous. 1991. Vegetable Production Guide for Commercial Growers. Province of British Columbia, Ministry of
Agriculture and Fisheries, Victoria, B.C.
Brust, G. E. and G. H. House. 1990. Influence of soil texture, soil moisture, organic cover, and weeds on oviposition
preference of southern corn rootworm (Coleoptera: Chrysomelidae). Environ. Entomol. 19:966-971.
Cusson, M., R. S. Vernon, and B. D. Roitberg. 1990. A sequential sampling plan for adult tuber flea beetles (Epitrix tu-
beris Gentner): dealing with “edge effects”. Can Entomol. 122:537-546.
Daniels, L. B. 1933. Potato flea beetle control. Colo. Sta. Bul. 400, May, 34 pp.
Duncan, D. B. 1955. Multiple range and multiple F tests. Biometrics 11: 1-42.
Finlayson, D. G. 1950. The effects of certain insecticides on the biotic potential of Epitrix tuberis Gentner (Coleoptera:
Chrysomelidae). M.Sc. Thesis, University of British Columbia, Vancouver, B.C.
Gaylor, M. J. and G. W. Frankie. 1979. The relationship of rainfall to adult flight activity, and of soil moisture to ovipo-
sition behavior and egg and first instar survival in Phyllophaga crinata. Environ. Entomol. 8: 591-594.
Giles, K. I. 1987. Estimation of an economic threshold for the tuber flea beetle, Epitrix tuberis Gentner (Coleoptera:
Chrysomelidae) on potato in British Columbia. Master of Pest Management Professional Paper. Simon Fraser Uni-
versity, Burnaby, B. C.
Grizzle, J. E., Starmer, C. F., and G. G. Koch. 1969. Analysis of categorical data by linear models. Biometrics 25: 489-
504.
Hill, R. E. and D. H. Tate. 1942. Life history and habits of the potato flea beetle in Western Nebraska, Epitrix cucumeris
(Harris). J. Econ. Entomol. 35: 879-884.
Hoerner, J. L. and C. P. Gillette. 1928. The potato flea beetle. Colo. Sta. Bul. 337, 16 pp.
Marrone, P. G. and R. E. Stinner. 1983a. Effects of soil moisture and texture on oviposition preference of the bean leaf
beetle, Cerotoma trifurcata (Forster) (Coleoptera: Coccinellidae). Environ. Entomol. 12: 426-428.
Marrone, P. G. and R. E. Stinner. 1983b. Effects of soil physical factors on egg survival of the bean leaf beetle, Cero-
toma trifurcata (Forster) (Coleoptera: Coccinellidae). Environ. Entomol. 12: 673-679.
McKeague, J. A. 1976. Manual on soil sampling and methods of analysis. Prepared by subcommittee of Canada Soil
Survey Committee on Methods of Soil Analysis. Soil Research Institute, Ottawa, Ont. 212 pp.
Vernon, R. S., J. R. Mackenzie, and D. L. Bartel. 1990. Monitoring tuber flea beetles, Epitrix tuberis (Coleoptera:
Chrysomelidae) on potato: parameters affecting the accuracy of visual sampling. Can Entomol. 122:525-535.
es
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 11
Hymenopterous parasites of the blackheaded budworm,
Acleris gloverana on Vancouver Island, British Columbia,
1970-1974
TOM GRAY and ROY SHEPHERD
FORESTRY CANADA, PACIFIC FORESTRY CENTRE, 506 WEST BURNSIDE ROAD, VICTORIA, BC
V8Z IMS
ABSTRACT
Thirteen hymenopterous parasites of the blackheaded budworm, Acleris gloverana Walsing-
ham, from Vancouver Island are compared with those found in British Columbia during the
1940-44 outbreak and outbreaks in the early 1950’s and mid-1960’s in Alaska. Six species of
the parasites reported were first records for British Columbia. Some of those reported may be
new species.
INTRODUCTION
The range of the blackheaded budworm, Acleris gloverana Walsingham, extends from west-
central Alaska along the Pacific Coast to northern California, and this insect occurs endemically
in the Selkirk Mountains of British Columbia (B.C.). Outbreaks have occurred approximately
every ten years (Prebble and Graham 1945b; Anonymous 1972). The decline of these cyclic in-
festations is not understood although some controlling factors suggested have been weather
(Silver 1960, 1963) and natural control (non-chemical) factors (Prebble and Graham 1945a&b).
The primary host of the budworm is western hemlock, 7suga sp. but the larvae also feed on
Abies, Larix, Picea, and Pseudotsuga (Powell 1962). During the 1940-44 outbreak, M.L. Preb-
ble (unpublished report) listed 48 different species of parasites of the blackheaded budworm.
Torgersen (1970) published a list of 16 different parasites which occurred in an Alaskan infes-
tation. The parasites reported in this study were from the infestation that occurred on Vancou-
ver Island from 1970 to 1974.
MATERIALS AND METHODS
During the outbreak period of 1970 to 1974, nine research plots were established to represent
western hemlock stands on Vancouver Island. These plots were used to develop a sampling
system (Shepherd and Gray 1990 a,b), and to investigate the population dynamics of this insect.
The samples consisted of 100 45-cm branches from each of eight locations and 200 45-cm
branches from another location for which defoliation estimates and the number of blackheaded
budworm were recorded. Branch samples were taken when the blackheaded budworm was at
the egg, early larval, late larval and pupal stages of development from 1972 to 1975. Black-
headed budworm larvae and pupae were placed individually in 3/4 oz. plastic containers to al-
low the parasites to emerge. Artificial diet (McMorran 1965) was provided for the larvae to
complete their feeding. The adult parasites were pinned and labelled, and representatives of
each species were sent to the Biosystematics Research Centre in Ottawa for identification.
RESULTS AND DISCUSSION
Percent parasitism during this infestation was initially quite low and, in fact, was undetectable
in some plots. Parasitism had increased by the second year of the outbreak. In 1972 the average
parasitism was 15% (7 plots, 2 plots had no parasitism), it increased to 53% (5 plots, 4 plots had
no parasitism) in 1973, but decreased to 13.5% (7 plots, 2 plots had no parasitism) in 1974
when the outbreak collapsed. By 1975, the high populations had disappeared and larvae were
not recovered from any of our study plots. Dipteran parasites were present in high numbers
compared to hymenopteran parasites (46 in 1972 (6 plots, 3 plots had no dipteran parasites) and
423 in 1973 (5 plots, 4 plots had no dipteran parasites)) but no parasite adults were obtained
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
12
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J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 13
from the puparia. Torgersen (1970) also had difficulty in obtaining adult emergence even though
he tried various temperatures and photoperiods to break what appears to be a parasite pupal di-
apause. There was considerable variation between the hymenopterous species recovered be-
tween outbreaks and also between locations (Table 1.). Of particular interest are: Charmon (=
Eubadizon) extensor, Mesochorus pictilis and M. sylvarum, Mesopolobus sp. (possibly n. sp.),
and Meteorus sp. (possibly n. sp.), which previously had not been reported attacking this host
in British Columbia or Alaska. These species may be capable of changing hosts as the oppor-
tunity arises. Of the sixteen species identified during this outbreak six species were first records
for British Columbia.
REFERENCES
Anonymous. 1972. Blackheaded budworm. A tree killer? Pac. For. Res. Cent., Victoria, BC Rep. P-4-72.
McMorran, A. 1965. A synthetic diet for the spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera:Tor-
tricidae). Can. Entomol. 97:58-62.
Powell, Jerry A. 1962. Taxonomic Studies on the Acleris gloverana-variana Complex, the Black-headed Budworms
(Lepidoptera: Tortricidae). Can. Entomol. 94: 833-840.
Prebble, M.L. and K. Graham. 1945a. The Current Outbreak of Defoliating Insects in Coast Hemlock Forests of British
Columbia. Part I Description of Outbreak and Damage. B.C. Lumberman Vol. 29(2): 25-27, 42, 44, 46, 48.
Prebble, M.L. and K. Graham. 1945b. The Current Outbreak of Defoliating Insects in Coast Hemlock Forests of British
Columbia. Part II Factors of Natural Control. B.C. Lumberman Vol. 29(3): 37-9, 88, 90, 92.
Shepherd, R.F. and T.G. Gray. 1990a. Distribution of eggs of western blackheaded budworm, Acleris gloverana (Wal-
singham) (Lepidoptera: Tortricidae), and of foliage over the crowns of western hemlock (Tsuga heterophylla (Raf.)
Sarg.) Can. Entomol. 122: 547-554.
Shepherd, R.F. and T.G. Gray. 1990b. A sampling system for eggs of western blackheaded budworm, Acleris glover-
ana (Walsingham) (Lepidoptera: Tortricidae), on western hemlock (Tsuga heterophylla (Raf.)Sarg). Can. Entomol.
122: 555-562.
Silver, G.T. 1960. The Relation of Weather to Population Trends of the Black-headed Budworm Acleris variana (Fern.)
(Lepidoptera: Tortricidae). Can. Entomol. 92: 401-410.
Silver, G.T. 1963. A Further Note on the Relation of Weather to Population Trends of the Black-headed Budworm,
Acleris variana (Fern.) (Lepidoptera: Tortricidae). Can. Entomol. 95:58-61.
Torgersen, Torolf R. 1970. Parasites of the Black-headed Budworm, Acleris gloverana (Lepidoptera: Tortricidae), in
Southeast Alaska. Can. Entomol. 102(10): 1294-1299.
Sex pheromone components of an undescribed
Choristoneura species (Lepidoptera: Tortricidae)
on lodgepole pine in British Columbia
T.G. GRAY*
FORESTRY CANADA, BRITISH COLUMBIA AND YUKON REGION, PACIFIC FORESTRY CENTRE,
506 WEST BURNSIDE ROAD, VICTORIA, B.C. V8Z 1M5
G. GRIES
DEPARTMENT OF BIOLOGICAL SCIENCES, SIMON FRASER UNIVERSITY, BURNABY, B.C.
V5A 186
*To whom correspondence should be addressed
ABSTRACT
F'\1-tetradecenyl acetate (E11-14 OAc) and Z11-tetradecenyl acetate (Z11-14 OAc) are sex
pheromone components of an undescribed, pine-feeding Choristoneura (C. n. sp. CPG=Prince
George) in British Columbia. Compounds were identified by coupled gas chromatographic-
electroantennographic (GC-EAD) and coupled gas chromatographic-mass spectroscopic (GC-
14 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
MS) analyses, and were field tested near Prince George, B.C. A 65:35 blend of £11-14 OAc and
Z11-14 OAc attracted as many male C. n. sp. CPG as did the most attractive virgin females, sug-
gesting that the natural sex pheromone has only two significant components. This two-compo-
nent blend is suggested for detecting and monitoring C. n. sp. CPG populations.
INTRODUCTION
There is a large complex of Choristoneura species feeding on a variety of coniferous and de-
ciduous trees in British Columbia (Freeman 1967; Powell 1980). The taxonomic relationships
of these tortricid moths are not clear and new entities are still being discovered. Comparative
morphology and ecology indicate that an undescribed Choristoneura species (C. n. sp. CPG =
Prince George) occurs on lodgepole pine (Pinus contorta var. latifolia) in an area 200 km north
to 40 km south of Prince George with concentrations near Bear and McLeod Lakes (T.G. Gray,
unpublished observations). Approximately 35% of the larvae were found feeding in and around
the staminate cones. They were difficult to detect unless disturbed. This feeding behaviour re-
sembles that of C. Jambertiana on lodgepole pine near Yahk, B.C. (T.G. Gray, unpublished ob-
servations) and that of another undescribed species (C. n. sp. CR = Richmond) on Scots pine
(Pinus sylvestris) (Gray and Slessor 1989).
Because sex pheromones provide important information on the taxonomic relationships of
moths (Roelofs and Comeau 1969; Roelofs and Brown 1982), we have conducted laboratory
analyses and field experiments to characterize the sex pheromone components of this C. n. sp.
CPG.
METHODS AND MATERIALS
Insect Rearing. In June 1989, three hundred larvae in the penultimate instar were collected
from immature fringe lodgepole pine between Woodpecker and Carswell, B.C., for rearing and
isozyme analysis. Twenty-five larvae were reared in each of twelve containers with ten cubes
of artificial diet (Robertson 1979) at 23 C, 50% RH, and a photoperiod of 16:8 (L:D). Pupae
were kept either in cages with potted lodgepole pines or in kraft paper bags with waxed paper
strips to provide emerging females with oviposition sites. Eggs were transferred to petri dishes
in black plastic bags (Stehr 1954) to induce first instar larvae to spin hibernacula. After 3 weeks
at 20°C, the larvae were kept at O°C for 3 months to satisfy diapause requirements. Following
cold treatment, they were reared as above to pupation. Large larvae were subjected to elec-
trophoretic analyses. Adults were used for pheromone identification. Dead males were checked
for the presence of spicules on their aedeagi (Dang 1985).
Pheromone analysis. Sexed pupae were placed in petri dishes with moist filter paper at 17°C,
40-50% RH and a photoperiod of 16:8 (L:D) until adult eclosion. After 1.0, 1.5, 2.0 and 2.5 hrs
into the scotophase, the last 3-4 abdominal segments of 2- to 5-day-old virgin females were re-
moved. The abdominal tips were individually extracted for about 30 sec in 5 wl of redistilled
hexane, rinsed with an additional 5 wl of hexane and discarded. Each gland extract was tested
individually. Four wl were analyzed in a Hewlett Packard 5890 gas chromatograph, equipped
with a 0.25 mm x 30 m DB-1 column and 2 pl of the same extract in a Hewlett-Packard 5890
gas chromatograph coupled to a Finnigan MAT 700 ion trap detector (GC-MS) which was
equipped with a 0.25 mm x 20 m Supelcowax column. The oven temperature program for both
chromatographs were: constant at 55°C for 1 min, heated at 25°C/min to 175°C, constant at
175°C for 1 min, and then heated at 6°C/min to 250°C. Injector and detector temperatures were
180°C and 295°C, respectively. Additional gland extracts were subjected to gas chromato-
graphic analyses on a DB-210 column (0.25 mm x 30 m) utilizing both flame ionization (FID)
and electroantennographic detection (EAD) (Arm et al. 1975) (Fig. 1).
Field bioassay of candidate pheromone components. Field experiments were conducted in a
mature lodgepole pine stand 70 km north of Prince George. Each five-replicate experiment was
set up in a randomized complete block with traps at 40 m intervals. The delta 2-litre milk-car-
ton traps were suspended 2 m above ground and baited with polyvinylchloride dispensers
(Daterman 1974) impregnated with candidate pheromone components in HPLC grade hexane.
The 855 cm? trap surface was covered with the adhesive Tangle-Trap (Tanglefoot Company,
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 15
Z11-14: AC
E11-14:0H
FID E 11-14: AC | 211-14:0H
E 11-14: AC Z11-14: AC
Detector response
7 8 9 10 11 12
TIME (min.)
Figure 1: Detector responses to one female equivalent of pheromone extract chromatographed on a
Hewlett Packard 5859A instrument (DB-210 column, 0.25 mm x 30 m L.D., 1 min at 100°C, 20°C/min to
180°C, 1°C/min to 220°C). The antennal recording was carried out with a single antenna of male C. n. sp.
CPG (FID = flame ionization detector, EAD = electroantennographic detector).
Grand Rapids, MI 49504) to imobilize moths entering the trap. Traps were checked and ad-
vanced one position daily and those containing 20 or more males were replaced with a new trap
using the same bait. The first experiment tested the attraction of F11-tetradeceny] acetate (F11-
14 OAc), Z11-tetradecenyl acetate (Z11-14 OAc), F11-tetradecenol alcohol (E11-14 OH) and
Z11-tetradecenol alcohol (Z11-14 OH) alone and in combinations (Table 1). The second five-
replicate experiment tested the attraction of various doses of F11-14 OAc and Z11-14 OAc at
the natural 65:35 ratio (Table 2).
RESULTS AND DISCUSSION
GC-EAD analyses of female gland extracts revealed four compounds two of which elicited
antennal responses (Fig. 1). Retention indices and GC-MS analyses indicated F11-14 OAc,
Z11-14 OAc, E11-14 OH and Z11-14 OH. Synthetic F11-14 OAc and Z11-14 OAc elicited
strong electrophysiological responses, while the corresponding alcohols were hardly EAD-ac-
16 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
Table 1
Comparison of attractiveness of two acetate isomers and two alcohol isomers against Choristoneura n. sp.
(CPG) at a loading of 5% w/w of chemicals polymerized in PVC, at Bear Lake, BC in August 1990.
n=45
Dose Average No. males/
Lure (Wg) night/trap + S.D.
E/Z-11-14 OAc (750/500) 51.4a* +21.0
E/Z-11-14 OAc + E-11-14 OH (725/325/200) 454a +163
E/Z-11-14 OAc + E/Z-11-14 OH (725/325/100/100) 20.2)Ds VE 47 5
Female Choristoneura n. sp. (CPG) 10.2 c*¥* + 6.9
E-11-14 OAc (1250) 2.8.60 3:8
Z11-14 OAc (1250) 0.2c +04
E-11-14 OH (1250) Ose £10
Z-11-14 OH (1250) 0
Unbaited control trap 0
* Means followed by the same letter are not significantly different at P < 0.05 (Duncan’s New Multiple
Range Test).
** Average of five unmated females.
Table 2
Catches of male undescribed pine feeding Choristoneura (C. n. sp. CPG) in sticky traps baited with vari-
ous doses of a 65:35 blend of F11-14 OAc and Z11-14 OAc, Bear Lake, British Columbia, August 1991.
N=35:
Lure Dose Average No. Males caught/ fi
(wg) trap/night CI
F/Z-11-14:Ac (750) 14.8 a* 8.15
E/Z-11-14:Ac (2000) 14.6 ab 8.55
F/Z-11-14:Ac (2500) 14.0 ab 12195
E/Z-11-14:Ac (1250) 9.0 abc 10.55
E/Z-11-14:Ac (250) 6.4 be 14.35
E/Z-11-14:Ac (125) 0
* Means followed by the same letter are not significantly different (P<0.05) Tukey’s W Procedure.
tive, suggesting that they may not be part of the pheromone blend of female C. n. sp. CPG. Iden-
tical retention times on three columns with different retention characteristics (DB-1, DB-210,
Supelcowax) and identical mass spectroscopic chacteristics of female-produced and authentic
compounds confirmed our structural assignments.
E11-14 OAc, E11-14 OH, Z11-14 OAc and Z11-14 OH tested individually at 1250 wg each
did not attract male C. n. sp. CPG in the field test (Table 1). However, a binary combination of
F11-14 OAc and Z11-14 OAc at the 65:35 ratio found in gland extracts, attracted as many males
as did the most attractive virgin females. Five of the latter attracted an average of 10.2 males
each. Addition of 200 wg of E11-14 OH to the acetate blend did not affect the trap catches, while
addition of 100 wg of both £11-14 OH and Z11-14 OH significantly decreased attraction (Table
1). Significant effects on trap catches of the alcohols, comprising 5-40% of the chemical lure,
were not confirmed in subsequent experiments.
Pheromone quantity in gland extracts of female C. n. sp. CPG peaked 1.5 hours into the sco-
tophase. With 80 ng per female it exceeded those of other Choristoneura up to four times. Only
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 17
C. orae produces similar large amounts of pheromone (Cory et al. 1982; Gray et al. 1984). A
dose response test confirmed that large amounts of the acetate pheromone components are more
attractive than lower concentrations (Table 2). In contrast, only 2.5 wg of E11-tetradecenal alde-
hyde (£11-14 Ald) was sufficent to attract large numbers of C. occidentalis and C. biennis (Cory
et al. 1982). Lack of E11-14 Ald in the pheromone blend of C. n. sp. CPG contrasts with the
pheromone blend of female C. orae, which do produce small amounts of £'11-14 Ald in addi-
tion to large quantities of F11-14 OAc and Z11-14 OAc.
Isozymes and spicule numbers on the aedeagi of C. n. sp. CPG resembled those of other
Choristoneura species in B.C., but differed from eastern species (G.T. Harvey, Forestry Canada,
Sault Ste. Marie (retired) personal communication). Adults of C. n. sp. CPG are similar to C. n.
sp. CR but the forewings have a lighter background colour and the black strigulae are absent.
C.n. sp. CPG is close in size to C. lambertiana except that the forewings are not so light and
creamy in colour but ochreous with distinctive orange-brown markings. The males are darker
in wing colour than females, as observed in some other Choristoneura (Harvey, personal com-
munication).
The two-component blend of £11-14 OAc and Z11-14 OAc in a 65:35 ratio with the corre-
sponding alcohols being benign, and corresponding aldehydes being absent, differs from that of
other western conifer-feeding Choristoneura. Occurrence on lodgepole pine and sexual dimor-
phism further indicate that C. n. sp. CPG may be a new species.
CONCLUSION
A population of Choristoneura was detected near Prince George, British Columbia. Mor-
phological, ecological and pheromone characteristics are distinct from other Choristoneura
species in British Columbia. Larvae feed on staminate flowers of lodgepole pine. Male moths
are distinctly darker than female moths. The sex pheromone is comprised of E-11-tetradecenyl
acetate and Z-11-tetradecenyl acetate at a unique 65:35 ratio. Corresponding aldehydes are not
produced and corresponding alcohols are not behaviourally active. A lure containing 750 wg
E/Z-11-14 OAc at a 65:35 ratio is recommended for detection and monitoring of C. n. sp. CPG.
ACKNOWLEDGEMENTS
We thank the staff of the Forest Insect and Disease Survey, Forestry Canada, for field assis-
tance, R. Gries, Simon Fraser University, for GC-EAD analyses, J. Manville, Forestry Canada,
for the Ion Trap analysis, and R.F. Shepherd, Forestry Canada, for his encouragement and re-
view of an earlier draft of the manuscript.
REFERENCES
Arn, H., E. Stadler and S. Rauscher. 1975. The electroantennographic detector-A selective and sensitive tool in the gas
chromatographic analysis of insect pheromones. Z. Naturforsch. 30c: 722-25.
Cory, H.T., G.E. Daterman, G.D. Daves, Jr., L.L. Sower, R.F. Shepherd, and C.J. Sanders. 1982. Chemistry and field
evaluation of the sex pheromone of western spruce budworm, Choristoneura occidentalis, Freeman. J. Chem. Ecol.
8:339-350. |
Dang, P.T. 1985. Key to adult males of conifer-feeding species of Choristoneura Lederer (Lepidoptera:Tortricidae) in
Canada and Alaska. Can. Entomol. 117:1-5.
Daterman, G.E. 1974. Synthetic sex pheromones for detection survey of European pine shoot moth. U.S. Dept. Agric.
For. Serv. Res. Pap. PNW-180. 12pp.
Freeman, T.N. 1967. On coniferophagus species of Choristoneura (Lepidoptera:Tortricidae) in North America. Some
new forms of Choristoneura allied to C. fumiferana. Can. Entomol. 99: 449-55.
Gray, T.G. and K.N. Slessor. 1989. Morphology, life history and identification of sex pheromone components of an un-
described species of Choristoneura (Lepidoptera:Tortricidae) on Scots pine in British Columbia. J. Entomol. Soc.
British Columbia. 86:39-47.
Gray, T.G., K.N. Slessor, G.G. Grant, R.F. Shepherd, E.H. Holsten and A.S. Tracey. 1984. Identification and field test-
ing of pheromone components of Choristoneura orae (Lepidoptera:Tortricidae). Can. Entomol. 116: 51-56.
Powell, J.A. 1980. Nomenclature of nearctic conifer-feeding Choristoneura (Lepidoptera:Tortricidae): Historical re-
view and present status. U.S.D.A. For. Serv. Gen. Tech. Rpt. PNW-100. 18pp.
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Robertson, J.L. 1979. Rearing the western spruce budworm. U.S. For. Serv. Washington, D.C. CANUSA pamphlet.
18pp.
Roelofs, W.L., and R.L. Brown. 1982. Pheromones and evolutionary relationships of Tortricidae. Ann. Rev. Ecol. Syst.
13: 395-422.
Roelofs, W.L., and A. Comeau. 1969. Sex pheromone specificity: taxonomic and evolutionary aspects in Lepidoptera.
Science 165: 398-400.
Stehr, G. 1954. A laboratory method for rearing the spruce budworm, Choristoneura fumiferana (Clem.), (Lepidoptera:
Tortricidae). Can. Entomol. 86: 423-428.
Response of Trichogramma sp. nr. sibericum (Hymenoptera:
Trichogrammatidae) to age and density of its natural hosts, the
eggs of Rhopobota naevana (Lepidoptera: Tortricidae)!
LI, S. Y. and D. E. HENDERSON
E. S. CROPCONSULT LIMITED, 2962 WEST 15TH AVENUE, VANCOUVER, B. C. V6T 3A3
CORRESPONDENCE: S. Y. LI, DEPARTMENT OF PLANT SCIENCE, UNIVERSITY OF BRITISH
COLUMBIA, VANCOUVER, B. C., CANADA V6T 1Z4, TEL: (604)822-6916
ABSTRACT
Responses of an indigenous Trichogramma sp. nr. sibericum (Hymenoptera: Trichogrammati-
dae) to the age and density of eggs of the blackheaded fireworm, Rhopobota naevana (Hiibner)
(Lepidoptera: Tortricidae) were determined in the laboratory. The parasitoid wasp showed a sig-
nificant (P < 0.05) preference for eggs 1-7-day-old over those 21-day-old. No significant dif-
ferences (P > 0.05) in percentages of parasitized eggs, however, were found among groups of
eggs below 7-day-old. At host egg densities below 20 per wasp, the number of eggs parasitized
significantly (P < 0.05) increased with egg density, and tended to stabilize at densities above 30.
The rate of parasitism decreased significantly (P < 0.05) with increased host egg density. Su-
perparasitization occurred at densities of 5-10 host eggs, but was rarely observed at densities
above 20 eggs. The mean number of progeny per wasp significantly (P < 0.05) increased with
host density, whereas the clutch size (the number of parasitoid offspring per parasitized host)
significantly (P < 0.05) decreased with an increase in host density.
INTRODUCTION
Although egg parasitic Trichogramma (Hymenoptera: Trichogrammatidae) species head the
list of beneficial insects as biological control agents (Stinner 1977), no studies have been re-
ported on using Trichogramma to control the blackheaded fireworm, Rhopobota naevana (Lep-
idoptera: Tortricidae), a major pest on cranberry in North America. However, the use of Tri-
chogramma to control this pest may be realistic and possible because two species of
Trichogramma have been discovered recently from natural fireworm populations in cranberry
fields in British Columbia (Li et al. unpublished data). One of the two indigenous species, 77i-
chogramma sp. nr. sibericum, showed a high affinity for fireworm eggs in the laboratory (Li et
al. unpublished data.). If this fireworm-attacking Trichogramma can be successfully mass
reared under laboratory conditions, field release for control of the fireworm may be realized.
Host age preference of Trichogramma towards a host is fundamental to a release program and
is a critical factor in selection of an effective Trichogramma as a biological control agent
(Marston and Ertle 1969; Schmidt 1970) because timing of a release is one of the most impor-
tant factors influencing efficacy in the field. Thus, host age preference by Trichogramma must
be determined before using the wasp in a biological control program. Knowledge of the rela-
tionship between host density and parasitism is also critical for both inundative releases in the
field and mass rearing in the laboratory. In the present study, we report the effects under labo-
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 19
ratory conditions of host age and density on parasitism of fireworm eggs by a field-collected T.
sp. nr. sibericum. Our objectives were: (1) to determine which host egg stages the wasp prefers
to parasitize; (2) to determine the relationship between host egg density and parasitization; and
(3) to study the effect of host egg density on mean progeny per wasp and on the number of wasp
offspring per parasitized host egg (clutch size).
MATERIALS AND METHODS
Parasitoids
Parasitized fireworm eggs were collected from an abandoned cranberry field in Richmond,
near Vancouver, British Columbia. Cranberry leaves bearing the parasitized eggs were incu-
bated on moist filter paper in clear plastic Petri dishes (S50 by 9 mm) at 24 + 2°C, 90+10% RH,
and 16L:8D photoperiod in the laboratory. Eclosed females were used in the following experi-
ments.
Host eggs
Field-collected second-generation adult fireworm females were permitted to lay their eggs on
cranberry uprights in a cage at 24 + 2°C, 50+10% RH, and 16L:8D photoperiod in the labora-
tory. The uprights in the cage were replaced daily. Fireworm eggs obtained from the cage were
used as hosts in the following experiments.
General Methods
The experiments were conducted in the open laboratory at 24 + 2°C and 50+10% RH. The
fireworm eggs on cranberry leaves were placed in the Petri dishes (50 by 9 mm) lined with
moist filter paper, which was watered daily to prevent the leaves from drying out.
In each of the following experiments, single female parasitoids were transferred into a Petri
dish (50 by 9 mm) with fireworm eggs using a fine artist’s brush, and were maintained in the
Petri dish till their death. Following introduction, the wasps were immediately observed under
a dissecting microscope. If the wasps did not examine any of host eggs (i.e., measure the host
volume by their antennae) within 5 min following introduction, they were discarded and re-
placed. Seven days following introduction of the wasps, the host eggs were microscopically ex-
amined to determine if they were unparasitized, parasitized or superparasitized. The parasitized
eggs turned black when the parasitoids reached the prepupal stage of development, whereas un-
parasitized eggs remained yellow. Superparasitized eggs are those in which more than one 777-
chogramma offspring has developed from a single host. Superparasitism was determined by
counting the wasp offspring through the clear chorion of the parasitized host egg.
Host age preference
In this choice test, four each of 1, 3, 5, 7 and 21-day-old host eggs laid on cranberry leaves,
at two equal-aged eggs per leaf, were placed in the center of a Petri dish (50 by 9 mm). Single
Table 1
Effects of host egg density of blackheaded fireworm, Rhopobota naevana, on number of progeny and the
clutch size of Trichogramma sp. nr. sibericum'
Host density Progeny+SE Clutch sizetSE
5 7.60+0.31 b 1.52+0.06 a
10 11.80+0.73 ab | 1.46+0.06 a
20 11.70+1.53 ab 1.05+0.03 b
30 14.20+1.98 a 1.06+0.03 b
40 14.1041.55 a 1.10+0.07 b
50 13.9041.92 a 1.03+0.02 b
. Mean values followed by the same letters in the same column are not significantly different at the 5%
level of Scheffé’s F-test.
—
20 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
female parasitoids were introduced in the center of the 10 leaves, which bore a total of 20 vari-
ously aged fireworm eggs. Each Petri dish was a replicate, 50 replications were tested.
Host density
Single female wasps were exposed to 1-day-old fireworm eggs at different densities in the
Petri dishes (50 by 9 mm). The host egg densities were 5, 10, 20, 30, 40 and 50 eggs divided
equally on five cranberry leaves, respectively. Each Petri dish was a replicate and each host den-
sity was replicated 10 times. The data recorded were: the percentage of parasitization and su-
perparasitization; the number of progeny per parasitoid; and the clutch size.
Data analyses
Percentage of parasitism was calculated as the numbers of parasitized eggs divided by total
eggs exposed in each group in the experiments. Percentage of superparasitism was calculated
as the numbers of superparasitized eggs divided by total parasitized eggs. The data were trans-
formed as either arcsin / P or /x+0.5 before ANOVA (Zar 1984), where P represents the per-
centage of parasitization or superparasitization and x is mean progeny per wasp or the clutch
size. One-way ANOVA was used to estimate significances (P < 0.05). Significant differences
were compared among host age groups or among host densities, and were separated by
Scheffé’s F-test of multiple contrasts at P = 0.05 level.
RESULTS
The age of the host egg had a significant effect (F = 7.0; df = 4, 245; P=0.0001) on parasitism
of fireworm eggs by the wasps (Fig. 1). The percentage of parasitization was significantly lower
(P <0.05) for 21-day-old eggs than 1-7-day-old eggs, suggesting that T. sp. nr. sibericum prefers
to parasitize young fireworm eggs. Although parasitism varied from 61% to 72.5% among eggs
Percentage parasitization (%)
Age of host egg (in days)
Figure 1. Effects of host age on parasitization of Rhopobota naevana eggs by an indigenous 7ri-
chogramma sp. nr. sibericum. Vertical bars indicate standard errors of mean parasitism. Bars with the
same letters indicate that mean parasitism is not significantly different (P > 0.05; Scheffé’s F-test) (Zar
1984).
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 21
aged from 1-7 days, no significant (P > 0.05) differences were found within this age group.
The number of parasitized fireworm eggs increased significantly (F = 6.0; df = 4, 54; P=
0.0002) with host egg density, and tended to stabilize at host densities higher than 30 eggs (Fig.
2: A). The maximum number of parasitized eggs was about 13, suggesting that females of the
wasp had a limited supply of eggs. The percentage of parasitism significantly (F = 42.1; df =4,
54; P = 0.0001) decreased with increased host egg density (Fig. 2: B). At a parasitoid/host ratio
of 1/5, 100% of the host eggs were parasitized. However, only 30% of the eggs were parasitized
at a ratio of 1/50. Superparasitization also significantly (F = 22.5; df = 4, 54; P = 0.0001) de-
creased as host density increased beyond 10 host eggs per wasp (Fig. 2: C). At high para-
sitoid/host ratios (1/5 - 1/10), 40-50% of the parasitized eggs were superparasitized, which was
significantly higher (P < 0.05) than at low ratios (1/20 - 1/50).
The mean number of progeny produced per parasitoid at a host density of 5 eggs was signif-
icantly (P< 0.05) lower than at densities of 30 - 50 eggs (Table 1). At a host density of 30 eggs,
the number of progeny reached its maximum of 14.2. Then the number tended to stabilize even
though host density continued to increase. The clutch sizes at host densities of 5 - 10 eggs were
significantly higher (F = 22.3; df = 4, 54; P = 0.0001) than those at higher densities of 20 - 50
eggs (Table 1).
DISCUSSION
Much research has been previously conducted on host-age selection by Trichogramma spp.
(e.g., Marston and Ertle 1969; Pak et al. 1986). The relationships between a given 7ri-
chogramma and its host species may be different. Pak (1986) summarized six types of rela-
tionships between host age and parasitism by different combinations of Trichogramma species
and their hosts. The observed effect of host age on parasitism of fireworm eggs in this study ap-
peared to be Pak’s type II-a: i.e., reduced parasitism of the oldest host eggs. Female parasitoids
may use physical (e.g., size, shape, texture, movement), physiological and/or chemical cues
(e.g., kairomones) to recognize and parasitize their hosts (Arthur 1981; Pak et al. 1986). Hosts
used in the present study were second-generation fireworm eggs. Because more than 80% of
these eggs are in diapause (Fitzpatrick and Troubridge 1993), there may not be significant dif-
ferences in physical and physiological between young and old eggs. Therefore, the wasp’s pref-
erence for young eggs may be based on chemical cues. Vinson (1975) found a chemical factor
present in Heliothis virescens F. (Lepidoptera: Noctuidae) eggs to be important in host accep-
tance by an egg-larval parasitoid, Chelonus texanus Cresson (Hymenoptera: Braconidae). A
few studies have demonstrated that kairomones on moth scales play an important role in host-
finding by Trichogramma (Lewis et al. 1971, 1975; Thomson and Stinner 1990). Whether fire-
worm eggs or scales of the adult moth contain such kairomones is unknown.
The parasitism of fireworm eggs by T. sp. nr. sibericum is host density dependent, i.e., an in-
crease in host egg density leads to a reduction in the percentage of parasitized eggs as has been
found by Hirose et al. (1976) and Morrison et al. (1978) with other species. Figure 2 C shows
that the rate of superparasitism here decreases with an increase in host density. This is a com-
mon phenomena described by many researchers (e.g., Waage 1986, 1988). Wajnberg et al.
(1989) showed that the control of superparasitism of Ephestia kuehniella Zeller (Lepidoptera:
Pyralidae) by Trichogramma maidis Pintureau and Voegelé seems to be genetically determined.
In this study, however, superparasitism at a host density of 5 eggs was 50%, whereas at a host
density of 50 eggs it was 2.8%. Superparasitism of fireworm eggs by T. sp. nr. sibericum may
be an example of adaptive reproductive strategy proposed by Strand (1988) and Waage (1988).
Superparasitism is often viewed as a maladaptive mistake (Van Lenteren 1981). As long as a
parasitoid egg deposited in a host still has a finite probability of survival in competition with a
previously laid clutch, however, superparasitism may be advantageous (Bakker et al. 1985;
Strand 1988; Waage 1988). In the present study, two adult Trichogramma often were eclosed
successfully from single fireworm eggs. It would therefore be of prime interest to conduct ex-
periments to determine the relationship between fitness per host and the clutch size of the par-
asitoid.
Although T. sp. nr. sibericum prefers to parasitize young eggs (Fig. 1), they still parasitized
22 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
21-day-old eggs at the rate of 36%. In order to obtain maximum efficacy as a control in the field,
Trichogramma should be released within one week of egg deposition. The results, however,
also suggest that releasing Trichogramma three weeks following egg deposition may still have
a positive effect on the reduction of fireworm populations. The total fecundity per female T. sp.
nr. sibericum observed in this study was lower than those reported previously with other species
(Yu et al. 1984; Smith and Hubbes 1986; Hohmann et al. 1988). The low fecundity of the wasp
reported here may be due to unfed adults with honey. Yu et al. (1984) found that fed 7ri-
chogramma minutum Riley with honey produced 6 times of eggs as much as unfed wasps. The
16 A: Parasitized eggs
12
No. parasitized eggs
B: Parasitism
C: Superparasitism
Percentage (%) of parasitized eggs
on
oO
) 10 20 30 40 50
Number of host eggs available
Figure 2. Effects of host egg density on the number of parasitized eggs (A), percentage parasitism (B),
and percentage superparasitism (C) of Rhopobota naevana eggs by an indigenous Trichogramma sp. nr.
sibericum. Vertical bars indicate standard errors of means.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 23
findings that single female T. sp. nr. sibericum can parasitize about 13 fireworm eggs (Fig. 2: A)
and that a negative relationship between host density and parasitism exists (Fig. 2: B), should
be taken into account in both mass rearing this species in the laboratory and commercial release
in the field.
ACKNOWLEDGMENTS
We are most grateful to J.H. Myers (University of British Columbia, Vancouver, B. C.) for
allowing us to use her laboratory facilities for this study. We thank three anonymous reviewers
for their helpful comments on the manuscript and R. Feng for field and laboratory assistance.
Financial support was received from the Science Council of British Columbia in the form of an
Industrial Postdoctoral Fellowship to the senior author, the National Research Council of
Canada, British Columbia Cranberry Growers Association, and Ocean Spray Cranberries In-
corporation.
NOTE
1. Paper presented at the 91th Annual Meeting of the Entomological Society of British Columbia. October 23, 1992,
Simon Fraser University, Burnaby, B. C.
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lection. J. Appl. Entomol. 101: 55-64.
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chogramma evanescens (Hymenoptera: Trichogrammatidae). Ann. Entomol. Soc. Am. 63: 1319-1322.
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ing temperature and host. Entomol. experi. & appli. 42: 249-258.
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Gupta (ed.), Advances in parasitic Hymenoptera research. E. J. Brill, Amsterdam.
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Vinson, S. B. 1975. Source of material in the tobacco budworm which initiates host searching by the egg-larval para-
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mol. exp. appl. 53: 177-187.
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Variation in attack by Sitka spruce weevil, Pissodes strobi
(Peck), within a resistant provenance of Sitka spruce
RENE I. ALFARO and M. HULME
FORESTRY CANADA, PACIFIC FORESTRY CENTRE, 506 WEST BURNSIDE ROAD, VICTORIA, BC,
CANADA V8Z 1M5
C. YING
BRITISH COLUMBIA MINISTRY OF FORESTS, RESEARCH BRANCH, BASTION SQUARE,
VICTORIA, BC, CANADA V8W 3E7
ABSTRACT
Variation in tree height and numbers of attacks by the Sitka spruce weevil (= white pine wee-
vil), Pissodes strobi (Peck), were studied among families of a resistant provenance of Picea
sitchensis (Bong.) Carr. at two Vancouver Island sites. At Sayward, after 14 years, the number
of trees attacked varied by family from 0 to 80%. A significant association was found between
the percentage of trees attacked in a family and the mean height of the family. Tall families were
generally attacked more. At Fair Harbour (a clonal test), only 12% of the trees from the resis-
tant provenance have been attacked after seven years, with all but one of the attacks concen-
trated on one of the two families tested. A multigenic or multicomponent basis for resistance is
proposed and discussed.
INTRODUCTION
The Sitka spruce weevil (=white pine weevil), Pissodes strobi (Peck), is a major cause of fail-
ure in reforestation programs with Sitka spruce, Picea sitchensis (Bong.) Carr., in coastal British
Columbia (B.C.), Washington, and Oregon (Furniss and Carolin 1977). The adults emerge from
overwintering in early spring, and move to the 1-year old terminal shoot (leader) where the fe-
males lay eggs under the bark near the tip. If the weevil larvae become established, they move
downwards, mining and consuming the phloem and eventually killing the leader (Silver 1968).
In the literature, the successful colonization and destruction of the tree leader by P. strobi is gen-
erally called a weevil attack; this terminology is also used here. Repeated leader destruction
causes height-growth loss and stem deformities which reduce the tree’s value (Alfaro 1989a,
1992). Although the tree survives the attack, stunted trees are often suppressed by competing
vegetation (Alfaro 1982). Other important tree species damaged by this insect are eastern white
pine, Pinus strobus L., in eastern North America (MacAloney 1930), Engelmann spruce, Picea
engelmannii Parry, and white spruce, Picea glauca (Moench) Voss., in central British Colum-
bia and the prairie provinces (Stevenson 1967).
Analysis of several trials in British Columbia provided strong evidence of genetic variation
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 25
in the susceptibility of Sitka spruce to weevil damage (Ying 1991, Alfaro and Ying 1990). Ge-
netic resistance to weevil attack was also demonstrated for interior spruce by Kiss and Yanchuk
(1991). These analyses indicate that some provenances and families show resistance in the form
of reduced numbers of weevil attacks. This was the case in Sitka spruce trees from the Haney
provenance in trials at Sayward and Fair Harbour, which grew well and were the least damaged
(Ying 1991, Alfaro and Ying 1990). Mechanisms of resistance are currently under investigation;
one based on supernumerary resin canals has been proposed (E. Tomlin and J.H. Borden, per-
sonal communication, Simon Fraser University).
Ying (1991) noted that resistant provenances of Sitka spruce originate from areas of high
weevil hazard, such as Haney or Squamish on the B.C. mainland. He hypothesized that herbi-
vore selection may have favored a resistant gene pool in these areas so that survivors have high
levels of resistance. Alfaro and Ying (1990) identified the Skeena River area of B.C. as another
area where higher frequency of resistant individuals could be found. In this area, extensive hy-
bridization of Sitka with white spruce occurs. Variation in susceptibility among different Picea
species and their hybrids has been reported (Mitchell et a/. 1990).
Alfaro and Ying (1990) also demonstrated variation in the ability of trees to recover from
weevil damage, since the type of defect formed after attack varied by provenance and family.
Some provenances had above-average numbers of attacks per tree but still were able to develop
into merchantable trees. An example of tolerance to weevil damage was the Big Qualicum
provenance, which was among the tallest at the Sayward trial even though it sustained repeated
attacks.
The objectives of this paper were to examine the rates of repeated attacks among families,
trees and clones of the most resistant provenance found to date in B.C. (the Haney provenance),
and to describe some of the factors that determined attacks on individuals of this provenance.
In particular, we tested whether the demonstrated preference of the weevil for the tallest and
fastest growing trees in a plantation (Mitchell et al. 1990, Alfaro 1989b, Gara et al. 1971, Sil-
ver 1968) also holds true within the Haney provenance. For this study, we used data collected
at Sayward and Fair Harbour in 1988, 1991 and 1992.
MATERIALS AND METHODS
The Sayward provenance test was established in the spring of 1974 in the Salmon Valley, near
Sayward, B.C., with the purpose of comparing growth and survival of a collection of open-pol-
lination families from several B.C. provenances. The plantation was first attacked by P. strobi
when the trees were 5 years old. The site was assessed in the fall of 1988; for every tree we
recorded: total height, diameter at breast height (DBH), and the number of times the trees had
sustained weevil attack. Weevil attacks were recognized because, in most cases, remains of the
destroyed leader were present and pupal chambers were evident. The plantation originally con-
sisted of two blocks, A and B, but only Block B was assessed because Block A had suffered
flood damage. Block B consisted of 141 rows occupying 2.8 ha, and contained 4389 living trees
from 34 provenances. Each provenance consisted of a variable number of wind-pollinated fam-
ilies. The resistant Haney provenance, which was the object of this study, was represented by
81 trees from 8 families. Further details on this plantation and on the geographic location of
provenance sources can be found in Alfaro and Ying (1990).
The 1988 records for the Sayward plantation (Block B) were assessed to determine the num-
ber of past attacks and the height of trees in the Haney provenance. Because of limitations of the
experimental design of this test no attempt was made to analyze the components of the variance
or to calculate other genetic parameters. Instead, we relied on non-parametric tests of variance
and association. The Kruskal-Wallis test (Sokal and Rohlf 1969) was used to test for family vari-
ation in mean number of attacks per tree. The Spearman rank correlation coefficient (Sokal and
Rohlf 1969) was used to test for a significant association between percentage of trees attacked
in a family and mean family height. The same procedure was used to test for association be-
tween the mean number of attacks per tree in a family and mean family height.
The Fair Harbour plantation is a clonal trial (grafting) established in 1984 to test the repeata-
bility of provenance resistance to weevil attack observed in provenance tests (Ying 1991). The
26 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
donor parents (ortets) originated from trees in eight provenances tested at the Sayward site, plus
two trees from the Green Timbers plantation which showed high resistance to weevil attack (AI-
faro 1982). Eight trees from the resistant Haney provenance (four trees each from family 0 and
1) were included in the test. The layout of the test consisted of 16 blocks in which a total of 640
grafts were tested; each ortet was represented by 16 grafts (ramets), one ramet in each block.
The attacks on the ramets at Fair Harbour were counted in October 1991 and on the ortets at
Sayward in October 1992.
To determine if attacks on trees occurred independently of each other or if the presence of one
attack enhanced the probability of a subsequent attack on the same tree, the distribution of the
attacks per tree at both sites was compared to that expected from a Poisson distribution. Data
collected in 1988 were used for the analysis of the Sayward site and 1991 data for the Fair Har-
bour site. However, because of the low attack rates at Fair Harbour, a Chi-square-test of good-
ness-of-fit (Sokal and Rohlf 1969) was done only for the Sayward data.
Table 1
Mean tree height, number of Sitka spruce weevil attacks per tree and percent of trees attacked among trees
of the resistant Sitka spruce Haney provenance (standard deviation in brackets). Data collected in 1988 at
Sayward and in 1991 at Fair Harbour.
Mean No.
Location and Number Mean Ht attacks % trees
family No. of trees (m) per tree attacked
Sayward
0 6 6.6 (1.6) 0.3 (0.5) Be)
1 5 — - -
3 30 6.0 (1.2) tal (1.1) 60
4 22 5.3'(L.9) 052 17) 32
5 4 4.0 (1.0) 0:07 2(00) 0
8 yi 4.2 (0.6) 0.9 (1.6) 29
12 iy 5.1 (0.6) 0.4 (0.8) 29
13 5 6.0 (1.0) 1.8 GESE) 80
Fair Harbour
0 62 4.6 (0.9) 0.03 (0.25) Z
l 63 4.7 (0.9) 0.25. (0:54) Dp
* This family was present only at Sayward Block A, which was not assessed in 1988. An assessment in
1992 indicated that 60% of the trees in this family had been attacked at least once.
Table 2
Frequency distribution of Sitka spruce weevil attacks per tree among trees from the resistant Sitka spruce
Haney provenance. The expected frequencies from a Poisson distribution are given in brackets. Data col-
lected in 1988 at Sayward and in 1991 at Fair Harbour.
Attacks Sayward Fair Harbour
per tree No. trees' No. trees!
0 46 (36) 111 (109)
1 14 (29) 10°G5)
2 15 (12) 4 (j)
3 533) -
4 1h) -
1. For the Sayward site, a Chi-square-test detected a significant departure of the number of attacks per tree
from predicted Poisson frequencies (P<0.01). Because of the small number of attacks, and low cell fre-
quencies, no statistical tests were done on the Fair Harbour data.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 27
RESULTS
Sayward Test
The 1988 attack records indicated that only 43% of trees from the Haney provenance were
attacked one or more times, whereas 76% of the trees in the entire Sayward Block B had been
attacked. The percentage of trees attacked among families within the Haney provenance varied
significantly (Chi-square test, P<0.05) by family from 0% (Family 5) to 80% (Family 13) (Table
1). The mean number of attacks per tree for the Haney provenance was 0.8 (ranging from 0 to
4) which was about half of the mean number of attacks per tree recorded for the entire Block at
1.5 (range 0 to 7, Alfaro and Ying 1990). The mean number of attacks per tree varied signifi-
cantly among the Haney families from 0 (Family 5) to 1.8 (Family 13) (Table 1) (Kruskal-Wal-
lis Test, P<0.05).
The distribution of the number of attacks per tree departed significantly (Chi-square test,
P<0.01) from the values expected from the Poisson distribution, indicating a clumped distribu-
tion. There were higher numbers of trees that remained undamaged and higher numbers having
repeated attacks than expected if the attacks occurred at random (Table 2). This allowed us to
conclude that the presence of one attack on a tree enhanced the chances of a tree being attacked
again. Alfaro and Ying (1990) arrived at the same conclusion when they examined the attack
distribution for the entire Sayward Block B plantation.
In 1988, the Haney provenance trees averaged 5.5 m in height, almost 2 m taller than the av-
erage height for the entire site (3.6 m). However, there was considerable variation in height by
family (range 4.0 to 6.6 m). The Spearman rank correlation test detected a significant associa-
tion between the percentage of trees attacked in a family and the mean height of the family (rs
= 0.88, P=0.01) (Fig. 1). Because of the negative effect of weevil damage on height growth, this
correlation is only a measure of association, rather than a cause-effect relationship. No signifi-
cant correlation was found between the number of times an individual tree was attacked and tree
height.
Fair Harbour Test
Overall, 12% of the trees from the Haney provenance at the Fair Harbour site were attacked
(14 trees up to 1991). This is much lower than the 69% found for the entire site. As at the Say-
ward site, more trees had repeated attacks than predicted by the Poisson distribution (Table 2).
There were four trees attacked twice; if attacks occurred at random, only one tree would have
been so attacked (Table 2). However, because at this site weevil damage is still light and this re-
sulted in low cell frequencies, a Chi-square test was not done. All but one of the attacks occurred
among trees of Family 1, resulting in attack rates of 2% for Family 0 and 21% for Family 1
(Table 3). Mean height of the Haney ramets varied from 4.0 to 5.2 m. No correlation was found
between the percentage of trees attacked in a clone and mean clonal height (Spearman rank cor-
relation test not significant).
A comparison of the attack rates on the Fair Harbour ramets with attack rates on the respec-
tive ortets at Sayward indicated a very good correspondence (Table 3). There was a very low at-
tack rate on both ortets and ramets from Family 0, with only one tree being attacked at each site.
Both ortets and ramets from Family 1 had sustained higher attack rates than Family 0, with three
of the four ortets at Sayward and 13 of 63 ramets at Fair Harbour being attacked (Table 3). In
both families there was one ortet attacked at Sayward but no attack among the respective Fair
Harbour ramets. There were also attacks among ramets from ortets which remained free from
attack at Sayward, e.g. tree No. 6 from Family 1.
DISCUSSION
The low attack rate of the Haney provenance at the Sayward and Fair Harbour sites confirms
the existence of resistance to weevil attack in this provenance (Ying 1991, Alfaro and Ying
1990). This study also suggests that individual trees and families from the same Haney prove-
nance differ in degree of resistance.
The large number of trees of the Haney provenance that remained free from weevil attack at
both sites is probably not due solely to genetic resistance. One factor influencing the probabil-
28 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
Table 3
Attacks by the Sitka spruce weevil on two Sitka spruce families planted at the Sayward site and cloned at
the Fair Harbour site. Data collected in 1992 at Sayward and in 1991 at Fair Harbour.
Plantation
Sayward Ortets Fair Harbour Ramets
Attacks Grafts Grafts Attacks*
Family No. Tree No. Trees per tree alive attacked per graft
0 2 l 0 16 0 0
5 1 0 14 0 0
6 1 0 16 1 2
7 l 1 15 0 0
l l 1 1 15 0 0
2 ] 2 16 3 1
3 1 2 14 8 1.4
6 it 0 IE) 2 i
* Mean number of attacks on attacked grafts.
ity of attack on a tree is its rate of growth. Several reports indicate that the Sitka spruce weevil
prefers the fastest-growing trees in a stand (Mitchell et al. 1990, Alfaro 1989b, Gara et al. 1971,
Silver 1968). Alfaro and Ying (1990) found that, at the Sayward site, trees growing in patches
of severe attack were significantly taller (3.8 m) than trees growing in areas of low attack (3.5
m). This preference was also evident in this study among the trees of the resistant provenance
(Fig. 1). The only Haney family at Sayward which was free from weevil attack was Family 5,
which was also the shortest.
The preference of P. strobi for the fastest-growing families (even among the resistant prove-
nance) is different from the findings of Kiss and Yanchuk (1991) who found the opposite among
families of white spruce attacked by the same insect. A possible explanation for this apparent
contradiction is that P. strobi may seek to maximize the amount of larval food during host se-
lection. P. strobi larvae consume the leader phloem, therefore, leaders with thicker phloem are
probably more attractive than leaders with thin phloem. In Sitka spruce, thick phloem is corre-
lated with long leaders (Alfaro, unpublished data). It is possible that, because of the different
growth characteristics of white spruce (much slower growth than Sitka spruce) thick phloem
may be negatively correlated with leader length in this species. Therefore, a negative correla-
tion between attack rate and rate of growth would result. However, further research is required
to prove or disprove this hypothesis.
The spatial distribution of weevil attacks in a plantation is highly clumped (Alfaro and Ying
1990, Graham 1951). This study demonstrated that, at both test sites, attacks on trees from the
resistant provenance were also aggregated and that, once trees were attacked, their chances of
further attack increased. This distribution probably results from the low dispersal ability of the
weevil and from the tendency of the weevils to overwinter near the attacked tree. Moreover, the
formation of multiple leaders on attacked trees increases the probability of further attack. This
aggregation in the weevil population must be considered when selecting for resistance. A sus-
ceptible tree may appear resistant and be undamaged if it happened to occur in an area of low
weevil density. Therefore, selection for resistant trees should be done in areas of the plantation
of high weevil density.
The low overall attack rates among the Haney trees at the Fair Harbour site as compared with
the Sayward site (Table 2) could result from several factors which are different between the two
plantations. The Fair Harbour test was initiated 10 yr after the Sayward test, therefore trees
have had a shorter exposure to the. weevil. The Fair Harbour trees were clones produced by
grafting, and thus could differ from the wind-pollination trees at Sayward due to an influence of
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 29
100
90
80
70
60
50
40
30
20
10
0
Percent attack
3.5
Mean Family Height (m)
Figure 1. Relationship between the percentage of Sitka spruce trees in a family attacked by the Sitka
spruce weevil at Sayward and mean family height. All families (indicated by numbers) are from the re-
sistant Haney provenance. Data collected in 1988.
the root stock on the physiology of the tree. However, the ranking of resistance among the two
families was the same at both sites: Family 0 was more resistant than Family 1 (Table 3). This
indicated that selection for resistance at an early age (9 years at Sayward) may be reliable.
The large variation in the percentage of trees attacked among the wind-pollination families
of the Haney provenance, as well as the existence of a gradation in resistance with several
provenances showing intermediate resistance, e.g. Squamish (Alfaro and Ying 1990), suggest
a resistance mechanism that has a multi-allelic or multigenic basis or to the existence of several
resistance mechanisms which accumulate and perhaps synergize in different trees. Future re-
search should concentrate on the elucidation of the resistance mechanisms and on understand-
ing their genetic basis. Ying (1991) noted the desirability of developing varieties which coin-
bine different resistance mechanisms and thus run a lower risk of inducing the evolution of
weevil populations which can overcome tree resistance. However confirmation of this hypoth-
esis requires the establishment and evaluation of progeny tests.
Ultimately, it is likely that the degree of attack by P. strobi on a Sitka spruce tree, family, or
provenance is due to a combination of factors: resistance factors and growth characteristics of
the trees which are subject to both genetic and environmental influences, plus an element of
chance. Some of these factors could be manipulated, along with silvicultural treatments such as
shading (McLean 1989) or spacing (Alfaro and Omule 1990), in an integrated pest management
program for control of this destructive insect.
LITERATURE CITED
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B.C., March 12, 1992. B.C. Ministry of Forests, Prince Rupert Region.
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provenances and families near Sayward, British Columbia. Can. Ent. 122:607-615.
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MacAloney, H.J. 1930. The white pine weevil (Pissodes strobi). For. Tech. Pub. No. 28. 87 pp.
McLean, J.A. 1989. Effect of red alder overstory on the occurrence of Pissodes strobi (Peck) during the establishment
of a Sitka spruce plot. Pp 167-176 in Alfaro, R.I. and S. Glover (Eds.), Proc. IUFRO Working Group Meeting on
Insects Affecting Reforestation. Vancouver, B.C. Canada.
Mitchell, R.G., K.H. Wright and N.E. Johnson. 1990. Damage by the Sitka spruce weevil (Pissodes strobi) and growth
patterns for 10 spruce species and hybrids over 26 years in the Pacific Northwest. USDA For. Serv. Pacific North-
west Res. Stn. Res. Pap. PNW-RP-434. 12 pp.
Silver, G.T. 1968. Studies on the Sitka spruce weevil, Pissodes sitchensis, in British Columbia. Can. Ent. 100:93-110.
Sokal, R.R. and FJ. Rohlf. 1969. Biometry. W.H. Freeman and Co. San Francisco. 776 pp.
Stevenson, R.E. 1967. Notes on the biology of the Engelmann spruce weevil, Pissodes engelmannii (Curculionidae:
Coleoptera) and its parasites and predators. Can. Ent. 99:201-213.
Ying, Cheng C. 1991. Genetic resistance to the white pine weevil in Sitka spruce. B.C. Ministry of Forests Res. Note
106. Victoria, B.C., Canada. 17 pp.
Life history and pheromone response in Pissodes schwarzi
Hopk. (Coleoptera: Curculionidae)
LORRAINE E. MACLAUCHLAN, JOHN H. BORDEN’
and INGRID PRICE’
B.C. FOREST SERVICE, KAMLOOPS FOREST REGION, 515 COLUMBIA STREET,
KAMLOOPS, B.C. V2C 2T7
ABSTRACT
Pitfall traps baited with live Pissodes schwarzi Hopk. males plus pine sections captured 46 fe-
male P. schwarzi from 1 June to 1 September, 1989, indicating the presence of a male-produced
sex pheromone. No weevils were captured in unbaited traps, or those baited with females on
pine or pine sections alone. Seasonal response of P. schwarzi females to the male-baited pifall
traps indicated peak periods of activity in early June, representing overwintered adults, and
mid- to late July, corresponding to the emergence of new adults. Development time of P.
schwarzi varied depending on oviposition location on the tree. Overwintered brood adults be-
gan to oviposit in May and continued through August.
INTRODUCTION
The Yosemite bark weevil, Pissodes schwarzi Hopk., attacks and breeds in the bole, root col-
lar and large roots of stressed or dying trees (Wood 1964; Stevens 1966). Hopkins (1911) and
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 31
Smith and Sugden (1969) list its hosts as Larix occidentalis Nutt. (western larch), Picea engel-
mannii Parry ex Engelm. (Engelmann spruce), P. glauca (Moench) Voss.(white spruce), P. mar-
iana (Mill.) B.S.P. (Black spruce), P. pungens Engelm. (blue spruce), Pinus ponderosa Laws.
(ponderosa pine), P. albicaulis Engelm. (whitebark pine), P. contorta Dougl. (lodgepole pine),
P. flexilis James (limber pine) and P. monticola Doug]. (western white pine). In British Colum-
bia, P. schwarzi is commonly found in lodgepole pine infected with comandra blister rust,
Cronartium comandrae Pk. (Furniss and Carolin 1977) or other damaging agents.
Host selection by another root-inhabiting Pissodes, P. nemorensis, has been shown to be
pheromone mediated (Fontaine and Foltz 1982). Males release grandisol and grandisal, origi-
nally found in the boll weevil, Anthonomus grandis Boheman (Tumlinson et al. 1969), which
attract both males and females (Phillips et al. 1984). Both P. schwarzi and P. nemorensis exhibit
similar habits, attacking boles and root collars of young trees. This study investigates the hy-
pothesis that P. schwarzi produces an aggregation pheromone and describes some aspects of the
weevil’s life history and habits.
MATERIALS AND METHODS
Pitfall traps modified slightly from those used to catch Hylobius abietis (L.) (Tilles et al.
1986a,b; Nordlander 1987) were constructed from 30 cm lengths of PVC plastic drainpipe with
a 10 cm inside diameter. The pipes were inserted into the soil so that 8 equidistant holes (6 mm
diam.) drilled around the circumference at mid-point of the pipe were at ground level. A thin
coating of Tanglefoot® was applied every 3 weeks to the above-ground portion of the trap to
catch any responding weevils that might climb the trap. Experimental traps all had a 4-5 cm long
section of fresh lodgepole pine wrapped in a fine mesh fabric and suspended at ground level in-
side the trap. The four treatments were: 1) one male inside the mesh fabric on a pine section; 2)
one female inside the mesh fabric on a pine section; 3) pine alone; and 4) an unbaited control.
The bait weevils were collected 20 May 1989 on lodgepole pines infected with comandra blis-
ter rust. Responding weevils that entered the holes in the trap fell into the bottom of the trap
where a plastic dish filled with anti-freeze fluid would trap and kill the insects. The inside of the
traps were coated weekly with Tri-flo® (teflon lubricant) to keep responding weevils from
climbing up the inside walls and escaping.
The traps were placed in a naturally-regenerated stand of lodgepole pine (average age 12
years) at Ellis Creek located in the montane spruce zone (Table 1) (Lloyd et al. 1990), 15 km
east of Penticton, B.C. The stand was juvenile-spaced in 1983 and had sustained about 35% in-
fection by C. comandrae. Approximately one third of the infected trees, or 10% of the trees in
the stand, showed past or current evidence of P. schwarzi infestation.
Between 21-23 May 1989, 60 traps were placed in 4 rows of 15 traps each, spaced about 12
m apart, with 15 m between rows. Treatments were assigned in 15 systematic, repetative com-
plete blocks, beginning at the start of the first row and ending at the last trap of the fourth row.
Table 1
Description of biogeoclimatic zones and subzones sampled in this study. Zones are generally named after
one or two dominant climax tree species and two lower-case alphabetic characters are used to denote cli-
matically based subzone names (Lloyd et al. 1990; Meidinger and Pojar 1991). The single numeric char-
acter following a subzone’s alphabetic character indicates a variant, numbered geographically from south
to north.
Characteristics IDFdm1 MSdm1 ESSFdcl
Site Okanagan Falls Ellis Creek Daves Creek
Zone Interior Douglas-fir | Montane spruce Engelmann spruce-subalpine fir
Subzone dry, mild dry, mild dry, cold
Elevation (m) 560-1,300 1,300-1,600 1,600-1,950
Annual mean temperature (°C) 3.8 32 2.0
32 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
25
20
re)
© —~
i= O
O. 15 ©
i Mitrap catch =
3 > Mean daily temp. S
ro) o
2 10 =
9 2
Ze
5
0
1 15 30 6 15 30 4 10
June July August
Figure 1. Numbers of Pissodes schwarzi caught in pitfall traps, by collection date, from June 1 to Sep-
tember 1, 1989, and corresponding average daily temperature for each period of elapsed time between col-
lection dates. All pitfall traps were located in the Ellis Creek drainage.
85
3
225
=
a
B 2
©)
@
oe
=
©
ee
0.5
0)
1 aS) 1 15 1 18 1
July August september October
Figure 2. Seasonal trend in numbers of eggs laid by newly emerged Pissodes schwarzi females per 3-7 day
periods, from July through October, 1989.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 33
At approximately weekly intervals from 1 June to 1 September 1989, captured weevils were
collected, and the pine, and weevil baits if necessary, were replaced. Captured weevils were sep-
arated by sex (Harman and Kulman 1966).
To study the bionomics of P. schwarzi, 5 to 8 infested pine roots were collected at approxi-
mately weekly intervals from 1 June to 23 August 1988 from 3 sites, located in three different
biogeoclimatic zones and subzones, in the Penticton area (Okanagan Falls, Daves Creek, and
the trapping site, Ellis Creek) (Table 1). The roots were subdivided into bole, root-ball, and lat-
eral roots, and dissected; the numbers of weevils in each life stage, as well as empty chip co-
coons were recorded.
Infested roots were collected from Ellis Creek on 21 May 1989 and the adults were allowed
to emerge in the laboratory. The weevils used in the study emerged between 9-20 June 1989.
Oviposition by emergent weevils was studied by placing 39 male-female pairs of P. schwarzi
on 6 cm lengths of fresh pine in a 15 x 2.5 cm petri dish on 21 June, 1989. The 39 petri dishes
containing the weevils were kept in a sceen house under natural light:dark and temperature con-
ditions. The pine was replaced every 3-5 days and assessed for oviposition. Observations from
dissections and the trapping study were related to weather recorded by the B.C. Forest Service
about 2 km from the Ellis Creek site, at the same elevation.
RESULTS AND DISCUSSION
Forty-eight P. schwarzi were captured throughout the summer in traps baited with males on
pine sections (two of these were captured in the Tanglefoot). No weevils were captured in un-
baited traps, or those baited with females on pine or pine sections alone. Forty-six of the P.
schwarzi captured were females, indicating a male-produced sex pheromone. The lack of re-
sponse to all but the males-on-pine treatment suggests that P. schwarzi does not respond to an
attractive tree trunk silhouette for visual orientation, with or without host volatiles, similar to re-
sults obtained with H. radicus Buchanan (Hunt and Raffa 1989). Three Hylobius warreni and
one Magdalis sp. were caught in response to the male-on-pine treatment.
The seasonal response of female P. schwarzi to the male-baited pitfall traps indicates peak pe-
riods of activity in early June and mid- to late July (Fig. 1). Trap catches were generally high-
est in warm weather. The first seasonal peak probably represents overwintered adults, and the
second peak newly emerged adults. Adults were collected from around the boles of stressed
pines on 10 May 1989 and all 6 of the females collected were ovipositing. These females when
paired with males laid 4.1 + 0.3 eggs per day (mean + S.E.) from 10 May to 1 June 1989.
Dissections of infested roots collected periodically from the three locations throughout the
summer revealed a fairly high frequency of larvae in the host from early June, to the end of Au-
gust. The frequency of pupae increased from late June through late July, and decreased in Au-
gust. The frequency of adults in the host varied only slightly between sites, and generally in-
creased from late July to early August. Separation of larval instars visually into early versus late
disclosed that late instars were most frequent in early June and August, and early instars from
mid-June through late July, corresponding to the observed activity of overwintered adults in the
field. As also noted by Stevens (1966), all developmental stages were represented during July
and August. However, in B.C. overwintered adults can be found mating, feeding and oviposit-
ing on boles as early as May and this has been observed to continue through August, as opposed
observations in California (Stevens 1966) where the first sign of oviposition was noticed in
July. Because of the protracted oviposition period, overwintering larvae of all stages may be en-
countered (Stevens 1966; personal observations).
Developmental time varied depending on the oviposition site on the tree. The preferred
Oviposition site was the lower bole (>80%) with the remainder occurring equally in the root-ball
and lateral roots. Developmental time in the bole can be as much as a year shorter than in the
root ball or lateral roots due to higher above-ground temperatures (personal observation). Some
infested trees were identified and checked periodically throughout the summer to observe de-
velopment in the field. Weevils developed and emerged from the above-ground portions of the
trees whereas many weevils in the below-ground portions of the trees overwintered as larvae or
pupae for a second winter. About 50% of infested trees that were dissected from the three sites
34 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
had empty chip cocoons, from which adults had already emerged and the majority of the emer-
gence was from the bole. The collections made from Daves Creek (ESSF), had >90% of the co-
coons located in the above ground portion of the bole. This could be due to a preference for
Ovipositing on the bole in the cool temperature regime in this biogeoclimatic zone.
From 12-18 July 1989, 22 to 28 days after being placed on host sections in petri dishes, the
females began ovipositing aid continued until 2 Oct. (Fig. 2). There appeared to be a major peak
in late July through August, and then a lesser one in October. Weevils could be found oviposit-
ing on boles in the field until late September in 1989. The mean number of eggs laid per female
(+ S.E.) was 22.6 + 1.82, with a maximum of 92 eggs laid by one female. There were up to 5
eggs deposited per puncture; however, of the 904 oviposition punctures examined, 86% con-
tained 1 egg and 12%, 2 eggs.
According to Stevens (1966) mating occurs on the foliage, with oviposition taking place
throughout the summer. Our observations and data (Fig. 2) support Stevens (1966) observation
regarding oviposition; however, mating was only observed on the bole of lodgepole pine. Mat-
ing locations may differ between geographic areas or climatic regimes, or perhaps Stevens
(1966) observed Pissodes terminalis mating on the foliage and did not distinguish it from P.
schwarzi.
Aggregation pheromones were reported for P. nemorensis by Booth and Lanier (1974).
Males produced a pheromone that when deployed with host odors attracted conspecific males
and females (Booth et al. 1983). P. strobi and P. nemorensis both produce grandisol (cis-2-iso-
propenyl-1-methylcyclobutaneethanol), and its corresponding aldehyde, grandisal, which act
together as aggregation pheromones for P. nemorensis (Booth et al. 1983; Phillips and Lanier
1986). Phillips and Lanier (1986) found that male P. strobi produce an unknown allelochemi-
cal that interrupts the response of P. nemorensis to its natural or synthetic aggregation
pheromone. Although Booth and Lanier (1974) postulated that P. strobi uses a male-produced
aggregation pheromone, repeated field tests have indicated that grandisol and grandisal are not
pheromones for P. strobi (Booth and Lanier 1974; Phillips 1981; Booth et al. 1983). We hy-
pothesize that a similar relationship to that between P. nemorensis and P. strobi could occur be-
tween the lodgepole terminal weevil, P. terminalis Hopping, and P. schwarzi, which spatially
occupy similar host sites.
Commonly, P. schwarzi infests trees stressed by rusts, Cronartium comandrae, root rots and
other insects, such as Cylindrocopturus spp. (Coleoptera: Curculionidae) (Wood 1964; Stevens
1966; Coulson and Franklin 1970), which are in themselves damaging or fatal. Therefore, P.
schwarzi 1s not economically important at present, but with increasingly intensive silvicultural
practices, e.g. spacing, and the probable onset of climatic warming trends, P. schwarzi could
well emerge as a problem in some circumstances, particularly because of its tendency to infest
apparently drought-stressed trees (personal observation).
ACKNOWLEDGEMENTS
We thank L.J. Chong and J.R. Thompson for technical and field assistance. The research was
supported by the Federal/Provincial Forest Resource Development Agreement (FRDA I) Grant
No. F-52-41-107.
NOTES
1. Centre for Pest Management, Department of Biological Sciences, Simon Fraser University, Burnaby, B.C. VSA 1S6
2. Department of Psychology, University of British Columbia, Vancouver, B.C. V6T 1W5
REFERENCES
Booth, D.C. and G.N. Lanier. 1974. Evidence of an aggregation pheromone in Pissodes approximatus and P. strobi.
Ann. Entomol. Soc. Am. 67: 992-994.
Booth, D.C., T.W. Phillips, A. Claesson, R.M. Silverstein, G.N. Lanier and J.R. West. 1983. Aggregation pheromone
components of two species of Pissodes weevils (Coleoptera: Curculionidae). J. Chem. Ecol. 9: 1-12.
Coulson, R.N. and R.T. Franklin. 1970. The occurrence of Dioryctria amatella and other insects in Cronartium fusiform
cankers. Can. Entomol. 102: 353-357.
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Fontaine, M.S. and J.L. Foltz. 1982. Field studies of a male-released aggregation pheromone in Pissodes nemorensis.
Environ. Entomol. 11: 881-883.
Furniss, R.L. and V.M. Carolin. 1977. Western forest insects. USDA Forest Service Misc. Publ. No. 1339.
Harman, D.M. and H.M. Kulman. 1966. A technique for sexing live white pine weevils, Pissodes strobi. Ann. Ento-
mol. Soc. Am. 59: 315-317.
Hopkins, A.D. 1911. Technical papers on miscellaneous forest insects. I. Contribution toward a monograph of the bark-
weevils of the genus Pissodes. USDA Bur. Entomol. Tech. Ser. 20: 1-68.
Hunt, D.W.A. and K.F. Raffa. 1989. Attraction of Hylobius radicis and Pachylobius picivorus (Coleoptera: Curculion-
idae) to ethanol and turpentine in pitfall traps. Environ. Entomol. 18: 351-355.
Lloyd, D., K. Angrove, G. Hope and C. Thompson. 1990. A guide to site identification and interpretation for the Kam-
loops Forest Region. Res. Branch, Min. Forests, Victoria, B.C.
Meidinger, D. and J. Pojar. 1991. Ecosystems of British Columbia. Research Branch, Min. of Forests, Victoria, B.C.
Nordlander, G. 1987. A method for trapping Hylobius abietis (L.) with a standardized bait and its potential for fore-
casting seedling damage. Scand. J. For. Res. 2: 199-213.
Phillips, T.W. 1981. Aspects of host preference and chemically mediated aggregation in Pissodes strobi (Peck) and P.
approximatus Hopkins (Coleoptera: Curculionidae). MS Thesis. State University of New York. College of Envi-
ronmental Science and Forestry. Syracuse.
Phillips, T.W. and G.N. Lanier. 1986. Interspecific activity of semiochemicals among sibling species of Pissodes
(Coleoptera: Curculionidae). J. Chem. Ecol. 12: 1587-1601.
Phillips, T.W., J.R. West, J.L. Foltz, R.M. Silverstein and G.N. Lanier. 1984. Aggregation pheromone of the deodar wee-
vil, Pissodes nemorensis (Coleoptera: Curculionidae): isolation and activity of grandisol and grandisal. J. Chem.
Ecol. 10: 1417-1423.
Smith, S.G. and S.A. Sugden. 1969. Host trees and breeding sites of native North American Pissodes bark weevils, with
a note on synonomy. Ann. Entomol. Soc. Am. 62: 146-148.
Stevens, R.E. 1966. Observations on the Yosemite bark weevil in California. Pan-Pacific Entomol. 42: 184-189.
Tilles, D.A., G. Nordlander, H. Nordenhem, H.H. Eidmann, A. Wassgren and G. Bergstrom. 1986a. Increased release
of host volatiles from feeding scars: a major cause of field aggregation in the pine weevil Hylobius abietis
(Coleoptera: Curculionidae). Environ. Entomol. 15: 1050-1054.
Tilles, D.A., K. Sjodin, G. Nordlander and H.H. Eidman. 1986b. Synergism between ethanol and conifer host volatiles
as attractants for the pine weevil, Hylobius abietis (L.) (Coleoptera: Curculionidae). J. Econ. Entomol. 79: 970-973.
Tumlinson, J.H., D.D. Hardee, R.C. Gueldner, A.C. Thompson, P.A. Hedin and J.P. Minyard. 1969. Sex pheromones
produced by male boll weevil: isolation, identification, and synthesis. Science 166: 1010-1012.
Wood, R.O. 1964. Notes on distribution and hosts of the weevils Pissodes schwarzi Hopk. and Pissodes curriei Hopk.
in British Columbia and Yukon Territory. Proc. Entomol. Soc. B.C. 61: 42-44.
A versatile wind-resistant insect cage
S.J. CLEMENTS, M.E. BERNARD and D.A. RAWORTH
RESEARCH STATION, AGRICULTURE CANADA, 6660 N.W. MARINE DRIVE
VANCOUVER, BRITISH COLUMBIA V6T 1X2
ABSTRACT
Ecological field studies often require cages that can withstand adverse weather conditions such
as high winds, without greatly altering environmental conditions within them. A large field
cage was designed, fabricated and tested for predator-prey studies on raspberry plantings. It
consisted of a wood base and screening suspended with loops of canvas from a framework of
PVC pipe. The cage withstood gusts above 70 km/h, did not appreciably alter temperature or
RH, but did reduce light by 40% and rainfall by 25%. The cage design is simple and can be
adapted to many experimental situations.
INTRODUCTION
Field cages have traditionally been designed with vertical walls and right-angled corners
(e.g. Fay and Meats 1987; Grant and Shepard 1985; and Savinelli et al. 1988). This shape pro-
vides ample standing room. However, rectangular cages have stability problems, particularly in
36 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
the 40 km/h winds frequently experienced in the Lower Fraser Valley of British Columbia. A
cage, 4.3 m long x 2.6 m wide x 2.1 m high and semi-elliptical, was designed and tested through
three field seasons during predator-prey studies in raspberry field plots.
MATERIALS AND METHODS
The cage (Fig. 1A) was made from a rectangular piece of fabric (Fig. 2) suspended from a
frame of PVC pipe (Table 1). The frame consisted of four poles arched between two sides of a
rectangular wooden base and made rigid at the top by one ridge-and two lateral-poles (Fig.
1:A,C). The fabric was sewn so that the seams lay along the length of the ridge- and lateral-poles
(Figs. 1A, 2). Cages constructed in 1990 were made entirely of grey noseeum screening while
those constructed in 1991 and 1992 were made of white noseeum screening, (Table 1) except
for the woven synthetic Lumite® roof panels [(Table 1; Fig. 2 (grey area)]. Fabric width was de-
termined as:
width = 2.22 x /(cage height)2 + (cage width/2)’
Canvas reinforcing sirips 8 cm wide were sewn onto the screen along the lines where the
PVC poles would lie (Fig. 2). Sleeves for the poles were made from a folded piece of canvas 13
cm wide, that was sewn along the centre of the reinforcing strip. The sleeves extended to within
Table 1
Materials used in field cage.
Item Specifications
Lumite® Saran screening 20.5 x 20.5 threads/cm
(light gold color) Chicopee
P.O. Box 2537
Gainesville, Georgia 30503-2537
Noseeum screening
(100% polyester)
Canvas
Nylon
Velcro
Poles
Wood
Poly-fastener®
Aluminium
Hardware -—pole assembly
— base assembly
11.0 x 59.0 threads/cm
Seattle Textile Co.
16 South Idaho, Seattle, WA 98134
waterproof, 283.5 gm weight (100z.)
waterproof, medium weight
2.54 cm width
PR 200 solvent-weld PVC pipe,
O.D. 2.67 cm,
4 x 5.7m (arch-poles),
3 x 4.3m (ridge- and lateral-poles)
rough cedar, 10 x 10 cm (4”x4"),
2 x 2.6m and 2 x 4.3m
PR 800 plastic track
Curry Industries Ltd.
Unit 5, 1031 Springfield Road
Winnipeg, Manitoba R2G 3T2
flat bar, 0.48 x 7.6 cm (“%6"x3.0")
30.5 cm per corner
hex head bolts, 0.64 x 6.4 cm
(A"x 2'4") National coarse threaded
nyloc nuts 0.64 cm (4”)
fender washers 0.64 (/4”)
wood screws, # 12 x 5.1cm (2”)
Robertson round head, cadmium plated
drywall screws — flat head, length
2.54-3.18 cm (1”"-174")
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 37
Figure 1. Field cage overview (A); aluminium corner bracket on wood base (B);
assembled lateral-pole and arch-pole (C).
8 cm of the pole intersections to allow room to bolt the ridge- and lateral-poles to the arch-poles.
A 12 cm strip of medium-weight, waterproof nylon was sewn around the edge of the fabric,
serving as the point of attachment between the fabric and the Poly-fastener® plastic track (Table
1) that was screwed to the wooden base. All seams were lock stitched on industrial machines
with Koban (cotton wrapped polyester) thread.
Cage assembly proceeded as follows: four 2.7 cm holes were drilled through each of the two
longest pieces of 10 x 10 cm wood in correct alignment to receive the arch-poles. The wood
base was bolted together with aluminium corner brackets (Fig. 1B). The channel portion of the
Poly-fastener® plastic track was attached near the top inside face of the wooden base with dry-
wall screws. With the netting laid flat on the ground (Fig. 2), the four PVC arch-poles were
pushed through their respective sleeves. Next the ridge-pole and two lateral-poles were inserted
through their sleeves so that they lay on top of the arch-poles. The ridge-pole was bolted in the
middle of the intersecting arch-poles (Fig. 1A). The arch-poles were bent and installed into
their respective holes in the 10 x 10 cm base. The nylon edge of the fabric (Fig. 2) was attached
to the base by snapping the insert strip into the channel of the Poly-fastener® track. The lateral-
poles were bolted to the arch-poles (Fig. 1C). The large piece of excess fabric remaining at each
comer was sealed off by looping the fabric in a knot and fastening the velcro strips (Fig. 2). Soil
was packed around the outer edge of the base to position the cage and limit insect movement.
Guy ropes and stakes were not used to stabilize the cage.
The cages were tested from Dec. 1989 - Oct. 1990, May - Nov. 1991 and Jun. - Sep. 1992 at
Abbotsford, British Columbia. Wind speed was measured with an RM Young anemometer
placed 2 m above the ground, 10 Jan. - 22 May 1990, and temperature and RH were measured
with HMP-112A Vaisala probes, 25 May - 3 Sep. 1990, and 12 Jun. - 11 Sep. 1992. All instru-
ments were linked to an Easylogger® 824-GP field unit which recorded hourly, averages of
readings taken at 5 min intervals for wind and 10 min intervals for temperature and RH. The
38 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
OTC RRR CATTANEO FLEES
EEE ES AE
Sats
Arch Sleeve
Ridge Sleeve
Lateral Sleeve
Cage height
we Ll ieee
- =a ererreree barre
ee he
jt OI AINE art
5.5 m.
Figure 2. Pattern for cage screening.
temperature and humidity probes were shielded by a 15 X 15 X 30 cm open-ended white box
located 1 m above the ground both inside and outside the cages. The wind data were augmented
with Environment Canada readings of daily maximum wind speed above 30 km/h, recorded 10
m above the ground, | km from the field site. Photosynthetically active radiation was measured
with a Li-Cor® 188-B photometer placed on the ground and 1.2 m above the ground inside and
outside of a cage on clear sunny days, 21 Jun. 1990 and 17 Jun. 1992. Rainfall was measured
with funnel rain gauges placed on the ground inside and outside of a cage, 7 and 13 Jun. 1990.
RESULTS AND DISCUSSION
Wind speeds recorded at 5 min intervals from 10 Jan. - 22 May 1990 were often greater than
30 - 40 km/h (Fig. 3). Maximum daily gusts recorded by Environment Canada during 3 yr that
the cages were field tested were: 30-40 (km/h), 29 times; 40-50, 23 times; 50-60, 10 times; 60-
70, 9 times; and 70-80, twice. Throughout, the PVC pipe simply flexed, allowing the wind to
spill off the top of the cage. One leeward arch-pole cracked near the base during winds of 40
km/h, but this was replaced and the event did not recur. Temperatures, measured inside a cage
constructed entirely of grey noseeum screening, were higher than outside; the opposite trend
was observed for RH, (Fig. 4). The difference between average daily temperature inside and
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 39
10°
10°
@
5
£ 10°
ro)
S 10
=
= |
za
10° |
0 10 20 30 40
Wind speed (km/hr)
Figure 3. Field cage exposure to winds from Jan. - May 1990. From readings taken at 5 min intervals, the
light bars indicate the number of hours in which the given maximum wind speed occurred and the dark
bars indicate the number of hours of a given average wind speed. The bars are plotted at the top of the
wind-speed interval (e.g. 0-5 km/h).
Temperature (C)
%RH
20 24 28
July 1990
Figure 4. Temperature and RH inside (dotted line) and outside (solid line) a field cage made entirely of
grey noseeum screening (1990).
40 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
Difference
8 12 16 20 24
Field temperature (C)
Figure 5. The difference between average daily temperature inside and outside a cage plotted as a func-
tion of temperatures outside: A, cage constructed with grey noseeum screening (1990) (y = -0.569 +
0.0650 x; p < 0.01; r=0.54; n = 99); and B, cage constructed with white noseeum screen and a Lumite®
roof (1992) (y = 0.376 - 0.0341 x; p< 0.01; r=0.52; n= 90).
outside a cage increased during hotter weather, (Fig. 5A). This pattern was reversed in 1992 in
cages constructed with white noseeum screening and a Lumite® roof, (Fig. 5B). The difference
between the two cage types was probably due to differences in screen reflectance, grey screen
(1990) vs white and light gold (1992). Radiation was reduced by 40% in the grey noseeum cage
and by 45% in the white noseeum, Lumite® cage. Rainfall was reduced by 25% inside the cage
constructed entirely of noseeum screening.
The cage cost $750.00: 1/3 for screening, 1/3 for all additional materials and 1/3 for sewing.
It can be constructed on site, or lifted over a field plot. It is easily dismantled by reversing the
order of assembly and all the parts can be stored in a linear bundle. The design and the nature
of the component parts make modifications for other plot sizes or other field crops exceedingly
simple. The component parts could also be modified for other experimental situations. For ex-
ample, in a wet environment, 10 cm black PVC pipe and corners could be substituted for the
10X10 cm rough cedar base. Given the strength of the cage, the ease of assembly, the similar-
ity of temperature and RH in and outside the cage, and the small storage requirements, it will be
very useful for ecological field studies.
ACKNOWLEDGMENTS
We thank the workshop staff, Al Olsen and Chris Jaeckel, at the Vancouver Research Station
for welding the aluminium corner brackets. Thanks also to Bill Ronald for assistance with the
technical drawing.
REFERENCES
Fay, H.A.C. and A. Meats. 1987. Survival rates of the Queensland fruit fly, Dacus tryoni, in early spring: field-cage stud-
ies with cold-acclimated wild flies and irradiated, warm- or cold- acclimated, laboratory flies. Australian Journal of
Zoology 35:187-195.
Grant, J.F. and M. Shepard. 1985. Techniques for evaluating predators for control of insect pests. Journal of Agricul-
tural Entomology 2:99-116.
Savinelli, C.E., J.S. Bacheler and J.R. Bradley. 1988. Ovipositional preferences of European corn borer (Lepidoptera:
Pyralidae) for field corn and cotton under field cage conditions in North Carolina. Environmental Entomology
17:688- 690.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 41
Effect of burning alfalfa stubble for
insect pest control on seed yield’
B.D. SCHABER%, J.F. DORMAAR, and T. ENTZ
AGRICULTURE CANADA RESEARCH STATION, P.O. BOX 3000 MAIN, LETHBRIDGE, AB,
CANADA TIJ 4B1
*Corresponding author.
ABSTRACT
Burning alfalfa (Medicago sativa (L.)) stubble in the spring has been shown to be effective
in reducing some insect pest populations. A study was conducted to determine the long-term ef-
fect of this practice on seed yield. Plots were established at Lethbridge, Alberta, and burned in
the spring or fall at various heights of plant growth from 1983 to 1989, with one half of each plot
treated annually with insecticides when the pest insects were in their most vulnerable stage.
Yields from burned treatments were not significantly different from unburned ones for the years
1983 to 1986, and 1988. In 1987, treatments burned in the fall had significantly higher yields
than other treatments. Burning at 15-20 cm of growth significantly reduced yield compared to
burning before spring growth. In 1989, yields from plots burned at 15-20 cm of growth were
significantly lower than those burned every fall or spring. Insecticide treated plots had signifi-
cantly higher yields in all years except 1983. Burning in the fall, or in the spring before growth,
increased gross economic returns, but insecticide treatment gave the highest returns.
INTRODUCTION
Burning alfalfa stubble is widely used by commercial growers of seed alfalfa (Medicago
sativa (L.)) as a method of controlling insect pests. Increased yields of alfalfa seed have been
reported from various cultivation and sanitation practices (burning) attempted by commercial
seed growers in Alberta and Saskatchewan (Lilly and Hobbs 1962; Bolton and Peck 1946). In
the short term, burning has been reported to reduce pest insect populations and increase seed
yields (Carlson 1940; Bolton and Peck 1946; Lilly and Hobbs 1962; Schaber and Entz 1988;
Tippens 1964). Despite lack of long term studies, alfalfa seed producers on the Canadian
prairies generally burn their seed fields in the spring of every second year.
An Integrated Pest Management (IPM) program was initiated and implemented in alfalfa
seed production areas of southern Alberta in 1978 (Schaber and Richards 1979). Such a system
should enable producers to increase the sustainability of their operations by reducing depen-
dence on costly pesticides which may also have adverse effects on the environment. Accurate
targeting of pesticides to control only damaging stages of insects, combined with other cultural
practices, should increase profits and reduce chemical use. Although this system has been in use
for some time, its scientific basis and practical merits had not been tested. This study was con-
ducted to assess the long-term effects on seed yield of annual or biennial burning of alfalfa stub-
ble in the fall, in the spring before growth, and at 5-10 cm and 10-15 cm of growth in the spring.
MATERIALS AND METHODS
Experiments were conducted for 7 years (1983-1989) at Lethbridge, Alberta, in an alfalfa
seed field (cv. Beaver), grown on a Dark Brown Chernozemic Lethbridge silty clay-loam soil.
The plots were seeded in 70 cm rows at 1.21 kg/ha. A split-plot design was used with five burn
treatments (12 X 15 m main plots) and two insecticide treatments (split-plots) with four repli-
cates. These small plots were established in order to have a high degree of control and unifor-
mity. Factors that we attempted to control were: irrigation, fertility, weeds, plot distance from
shelters for pollinating alfalfa leafcutter bees, and burning. Burn treatments were chosen as rep-
resentative of local seed producers’ management practices as follows: burned every fall (BEF)
(in October after harvest); burned every spring before growth (BES); burned alternate springs
before growth (BAS); burned alternate springs at 5-10 cm of new growth (BA2); burned alter-
42 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
nate springs at 15-20 cm of new growth (BA4); and control, no burn (UNB). The alternate burn
treatments occurred in 1983, 1985, 1987, and 1989. The plots were set aflame on the windward
side by a propane torch. To control the fire, one quarter of each plot was burned at a time.
Each burn treatment plot was divided in half and the same half was treated annually with in-
secticides when the pest insects were most vulnerable. To control the plant bugs, Lygus spp., and
Adelphocoris lineolatus (Goeze), trichlorfon (1150 g Al/ha per 110 1 H50) was applied two or
three times during the growing season when these bugs were in the fourth or fifth nymphal in-
stars, and their numbers had reached the economic threshold of 2/90° sweep. Phosmet (1125 g
Al/ha per 1101 HO) was applied in early June for control of the alfalfa weevil, Hypera postica
(Gyll.), when most of the larvae were in the third- or fourth-instars, and the numbers had
reached the economic threshold of 25/90° sweep. All treatments were randomly assigned at the
start of the experiment in 1983, and each plot received its assigned treatment for the 6 years of
the study.
The whole field received an application of 11-48-0 fertilizer (110 kg/ha) each year. The plots
were irrigated by sprinkler (12 hr at 12 mm/hr) twice during the growing season, once in late
May, and again about | wk before alfalfa leafcutter bees (Megachile rotundata F.) were placed
in the alfalfa fields, which was just as bloom commenced in late June. The stocking rate was ap-
proximately 60,000 bees/ha. In mid-September, fields were desiccated with diquat (0.6 kg Al/ha
per 200 1 H50, plus 0.1% of the total volume of the superfactant, Agral 90). About 7-10 d later,
two 2.45 m-wide cuts were straight combined using a Massey Harris combine (1963 model Su-
per 35, Brantford, ON). Alfalfa seed samples were cleaned before weighing.
Table 1
Alfalfa seed yields in kg/ha for each year from plots treated and not treated with insecticides at Leth-
bridge, Alberta.
1984 1986 1987 1988 1989
427+416.2a; 390+22.8a:.267+25.9a .4772197a 2764512:64
105£11.8b 2662£20.7b 210 2199b 2472) 83b e212 2 rerb
1983
Insecticide: L6d = 13a*
No-insecticide: 150 + 15a
Treatment
a,b Means within a given year followed by the same letter are not significantly different (P = 0.05, Ryan’s
Q test).
* Mean and standard error of the mean.
Table 2
Alfalfa seed yields in kg/ha for each year from plots variously treated at Lethbridge, Alberta.
Treatment* 1983 1984 1986 1987 1988 . 1989
UNB 156+15.0a@. 265+60.0a\ 278+50.3a 201428:9a. 325:35.0a;) 230 + 17 2Qabe
BES 153+22.6a 315+76.6a 336+47.2a 274+45.9b 348450.7Ja 272+24.2ab
BEF 212+33.6a 269+51.6a 334+30.0a 404428.0c 402+456.7a 295+22.5a
BASt 138+30.3a 251+66.7a 407+42.2a 2604+18.1b 3524+54.8a 2644 18.5abc
BA2+ 148+19.8a 2274+66.3a 266+29.5a 1664+16.2ab 327+474a 218+18.5bc
BA4+ 124+12.3a 269+68.0a 3464+49.2a 134+4+20.9a2 416+50.0a 196+ 14.3c
a,b,c Means within a given year followed by the same letter are not significantly different (P = 0.05,
Ryan’s Q test).
+ Burned in 1983, 1985, 1987, and 1989.
* UNB = control; BES = bummed every spring; BEF = burned every fall; BAS = burned alternate
springs; BA2 = bummed alternate springs 5-10 cm; BA4 = burned alternate springs 15-20 cm.
@ Mean and standard error of the mean.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 43
The data were analyzed as a split-plot design. The GLM procedure from SAS (SAS Institute
Inc., 1985) was used to perform analyses of variance, and Ryan’s Q test (Ryan 1960) was used
to evaluate differences among treatment means. Separate analyses were performed for each
year. Seed prices from each year were used to calculate the gross income per ha for each burn
treatment. The average alfalfa seed selling prices per kg were: in 1983, $2.20; 1984, $2.20;
1986, $3.19; 1987, $2.97; 1988, $2.31; and 1989, $1.98 (Gold Medal Seeds, Brooks, Alberta).
Seed yield data for 1985 are not included because very strong winds, up to 125 km/h, 1 wk af-
ter desiccation caused excessive shattering, and the amount of seed harvested was too small to
be included in the analysis.
RESULTS
The interaction between burning and insecticide treatment was significant only in 1983 (P =
0.02). Because the interaction occurred only in the year of stand establishment, the insecticide
and burn treatment effects are interpreted independently.
Insecticide treated plots had significantly higher yields for all years except 1983 (Table 1).
Seed yields increased from 1983 to 1986 (Table 2). Yields from burned treatments did not dif-
fer significantly from unburned, control treatments for 1983 to 1986, and 1988. In 1987, the
BEF treatment had a significantly higher yield than all other treatments, while plots burned at
15-20 cm of growth (BA4) had significantly lower yield than those burned before growth (BEF,
BES, BAS). In 1989, BA4 treatment yielded significantly less than BES and BEF treatments.
However, there was a consistent trend in the burn treatments as economic returns were higher
in the plots burned in the fall or before spring growth (Table 3).
DISCUSSION
Significant differences from burning were detected only in 1987 and 1989, however, the
long-term economic implications are still important. The mean economic returns for 6 of the 7
years are presented in Table 3 for the treatments with and without insecticides, so the economic
returns due to burning can be calculated. Maximum economic gain was from BEF; $188/ha
over UNB, $461 vs $649, (Table 3). Thus, the economic returns from BEF were 41% higher
than those from UNB. This is even more evident when burning and insecticides are applied to
seed alfalfa fields. No economic gains were realized from the BA2 and BA4 treatments. The dif-
ference in economic return between the insecticide and no insecticide treatments for UNB was
$282, indicating a substantial economic gain from insecticide application.
The fall burn treatment resulted in the highest yield (Table 2), but the average yield for the
unburned insecticide treatment was 14% higher than that for the BEF treatment (Table 3). How-
ever, if the cost of insecticide treatments is considered ($20-25/ha per application, usually two
treatments per year), then the returns from the BEF treatments are quite comparable ($649 vs
$700/ha). The average income was similar for the BES and BAS treatments, which may explain
why seed growers in this area generally burn their alfalfa seed fields in the spring before growth
once every two years. Although the BEF treatment produced the highest economic returns over
the 6 years, seed producers in southern Alberta generally don’t burn alfalfa stubble in the fall be-
cause of the possibility of soil erosion during the winter.
Insecticide treatments were applied when the damaging threshold for each pest species was
approached, but after early August insecticides were not applied, because it was believed that
late season (those occurring in alfalfa fields in mid- to late-August) pest insects did not cause
economic damage to alfalfa. Subsequently Schaber et al. (1990), showed that plant bugs can in-
deed cause economic damage in late August and need to be controlled. It is possible that these
late-season populations were responsible for the lack of consistent differences in yields between
treatments.
Schaber and Entz (1988) showed that small plots in a commercial seed alfalfa field, in Al-
berta, burned before growth in the spring had a significantly higher yield than unburned plots.
However, our experimental plots were surrounded by unburned untreated plots which provided
a ready supply of pest insects which moved into the treated plots within weeks after the insec-
44 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
Table 3
Gross income per ha (mean and standard error) from alfalfa grown for seed in six years* on plots treated
and not treated with insecticides.
Burm Treatment® No Insecticide Insecticide
UNB $461 + 48ab $743 + 69ab*
BES 518 + 59ab 889 + 84ab
BEF 649 + 59a 982 + 82a
BAS 528 + 69ab 892 + 86ab
BA2 422+41b 697 + 67b
BA4 448 + 65ab 791 +9lab
* 1985 data not included because of high winds and excessive shattering before harvest.
@ UNB = control; BES = burned every spring; BEF = burned every fall; BAS = bummed alternate
springs; BA2 = burned alternate springs 5-10 cm; BA4 = burned alternate springs 15-20 cm.
+, ++ burn treatment means not followed by the same letter are significantly different at P = 0.10 and P =
0.15, respectively, (Ryan’s Q test).
ticide treatment (Schaber and Entz 1991). Despite this, differences in yield were observable in
our small plots where immigration of pest insects readily occurred. Much greater yield differ-
ences might be expected in producers’ fields where immigration is less rapid. Likewise, Bacon
et al. (1983) and Kogan (1984) reported no strong correlations between alfalfa seed yields and
observed insect populations in experiments conducted on the control of pest insects.
Yield is only one factor of IPM, and focusing only on maximizing yield can result in exces-
sive costs and potentially detrimental environmental effects. Therefore, an IPM strategy that sta-
bilizes yield over time and is associated with acceptable profit might be preferred to one that
maximizes yield or profit in any one year. Thus, the cultural method of fall or spring burning of
alfalfa stubble before growth, as we have shown herein, 1s compatible with IPM principles and
sustainable agriculture.
ACKNOWLEDGEMENTS
The authors thank Gwen Dorchak for her assistance throughout the long-term burning
project.
NOTE
1. LRS Contribution no. 3879143.
REFERENCES
Bacon, O.G., R.H. James, W.R. Sheesley and E.T. Natwick. 1983. Research on insects affecting seed alfalfa. Univ.
Calif. Coop. Ext. Prog. Rept.
Bolton, J.L. and O. Peck. 1946. Alfalfa seed production in northern Saskatchewan as affected by Lygus bugs, with a re-
port on their control by burning. Sci. Agric. 26:130-137.
Carlson, J.W. 1940. Lygus bug damage to alfalfa in relation to seed production. J. Agric. Res. 61:791-815.
Kogan, M. 1984. Assessment of insect damage, pp. 31-51. /n Report XXII Planning Conference on Integrated Pest
Management, 4-8 June 1984, Lima, Peru.
Lilly, C.E. and R.A. Hobbs. 1962. Effect of spring burning and insecticides on the Superb Plant Bug, Adelphocoris su-
perbus Uhl., and associated fauna in alfalfa seed fields. Can. J. Plant Sci. 42:53-61.
Ryan, T.A. 1960. Significance tests for multiple comparison of proportions, variances, and other statistics. Psych. Bull.
57:318-328.
SAS Institute. 1985. SAS user’s guide: statistics, version 5 ed. SAS Institute, Cary, N.C.
Schaber, B.D., W.A. Charnetski and T. Entz. 1990. Early and late-season insecticide applications in seed alfalfa: Im-
pact on pest species and yield. J. Ent. Sci. 25:548-558.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 45
Schaber, B.D. and Entz T. 1988. Effect of spring burning on insects in seed alfalfa fields. J. Econ. Ent. 81:668-672.
Schaber, B.D. and T. Entz. 1991. Effect of annual and/or biennial burning of seed alfalfa stubble on populations of al-
falfa weevil and pea aphid. Ann. Appl. Biol. 119:425-431.
Schaber, B.D. and K.W. Richards. 1979. Integrated pest management on alfalfa grown for seed in southern Alberta. For-
age Notes. 24:17-19.
Tippens, H.H. 1964. Effect of winter burning on some pests of alfalfa. J. Econ. Ent. 57:1003-1004.
Phytoseiid mites associated with spider mites on hops in the
Willamette Valley, Oregon
W.B. STRONG and B.A. CROFT
DEPARTMENT OF ENTOMOLOGY, OREGON STATE UNIVERSITY, CORVALLIS, OR 97331
ABSTRACT
Densities and damage by twospotted spider mites, Tetranychus urticae Koch and levels of phy-
toseiid mites on hops were assessed in 34 commercial fields and at 11-19 sites of escaped hops
in the Willamette valley of western Oregon in 1991-1992. Amblyseius fallacis (Garman), Ty-
phlodromus pyri Scheuten, Amblyseius andersoni Chant and Metaseiulus occidentalis (Nesbitt)
were most common. On escaped hops, 7. pyri was more common than other phytoseiids. It oc-
curred widely on plants surrounding commercial hops including blackberry and other rosa-
ceous plants and probably is a vagrant on escaped hops. A. fallacis was most common in com-
mercial hops making up 88% of all specimens, followed by many fewer M. occidentalis and T.
pyri. Early spring survival of A. fallacis in commercial hops was poor because of certain cul-
tural practices used in the spring. Means to improve biological control of spider mites on hops
are discussed including amended methods of hop culture, use of selective pesticides and inoc-
ulative releases of predaceous mites.
Additional keywords: Amblyseius fallacis, Metaseiulus occidentalis, Typhlodromus pyri, Am-
blyseius andersoni, Tetranychus urticae
INTRODUCTION
Two-spotted spider mite (Tetranychus urticae Koch) (TSSM) is a major pest of hops and as-
sociated crops in the Willamette valley, Oregon. It overwinters in dead plant materials or on the
hop crown, emerging in early spring to feed on weeds and new hops shoots (Cone ef al. 1986,
Cranham 1985). Control of TSSM usually requires from one to several miticide sprays each
summer. Other pesticides such as aphicides sprayed for hop aphid (Phorodon humuli (Shrank))
and fungicides used for disease control may also affect TSSM and its predators. Because of pes-
ticide resistance in TSSM on hops (Campbell 1985), chemical control has been difficult. A bi-
ological control program for TSSM would be a desirable alternative to replace pesticides or to
augment their use.
Several biological control agents against TSSM have been reported from hops in arid regions
of western North America, but their usefulness has been limited because of non-selective pes-
ticide use (Pruszynski & Cone, 1972). These agents include several insect predators and phy-
toseiid mites. In central Washington, Metaseiulus occidentalis (Nesbitt) was the most common
phytoseiid; it emerged from the subterrenian crowns of hops in early April and then became
Sparse, reappearing in July (Pruszynski & Cone, 1973). Although there appeared to be some
pesticide tolerance in the central Washington strain of M. occidentalis, it did not control TSSM
to low levels.
Little is known about biological control on hops in the milder, more humid regions of west-
ern North America. This study was conducted to determine the beneficial species composition
and incidence of phytoseiids and spider mites on escaped and commercial hops in the more hu-
46 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
mid regions of Oregon, to measure early spring mortality of phytoseiids, and to monitor the dis-
persal of phytoseiids and TSSMs within and between hops and other crops.
MATERIALS AND METHODS
Commercial fields survey
Thirty-four commercial hop fields were surveyed 3 times each in 1991 and again in 1992.
From each field, 50 leaves were taken, 5 each from plants near 10 support poles. These poles
support wires at a height of 6 m, from which heavy twine is suspended; the hop vines grow up
the twine. Cracks in the wooden poles and in debris at the soil-pole interface are overwintering
sites for TSSM (Cone et al. 1986) and presumably for phytoseiids. Poles were selected from the
field edge to about 50 m toward the field interior. In May, all leaves were collected from near
the ground. In 1991, later samples were from 0-2 m, since TSSMs (and phytosetids) are con-
Table 1
Tetranychus urticae levels and phytoseiid mites found in commercial hop surveys, 1991-1992.
1991 1992
Early Mid Late Early Mid Late
Fields 34 34 34 32 31 29
% fields with mites 38% 76% 97% 81% 100% 86%
Mites/leaf in fields
with mites! 314.16 100+.2 9) «0 P18) 914.30 3.06+1.34 93+ 46
Mean damage on
infested leaves in
fields with mites' 1.10+.13 1.304.08 ©» 2.16£:.27 1.29%.08 *) 146+ 308 54.708: 07
Phytoseiids/field .06+.04 1Dt09"*" 2852187 634.37: "S3:00E1 57°" 252 E145
A. fallacis 2 76 10 83 688
T. pyri 4 6 5
M. occidentalis 2 24
Unknown (immatures) l o,| 4 25 18
Total phytoseiids 2 5 97 20 113 730
1. means + SE
Table 2
Commercial hop fields with elevated levels of Tetranychus urticae and/or Amblyseius fallacis.
Year Period Field Mites/leaf' Damage/infested leaf Phytoseiids/leaf
199] late 19 2.30+0.99 1.83+0.42 0.13+0.10
199] late 24 16.91+3.15 2.74+0.18 0.69+0.24
1991 late Zi 15,50+£1.97 2.24+0.13 0.02+0.02
199] late 28 19.82+4.56 2.59+0.20 0
1991 late 29 10.08+1.87 1.83+0.14 0
199] late 30 6.40+1.88 3.04+0.15 1.20+0.22
199] late 34 6.64+1.46 1.93+0.14 0
1992 Mid 18 20.02+4.47 2.58+0.14 0.86+0.40
1992 Mid 23 38.244+8.17 2.87+0.18 0.04+0.03
1992 Late 7 10.48+1.28 ZA THON 6.28+1.17
1992 Late 11 2.24+0.33 1.61+0.10 5.92+1.06
1. means + SE
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 47
centrated in these areas at these times (Sites & Cone, 1985). Later samples in 1992 were taken
from the ground to 6 m.
Survey times were early-season (May 3-10 in 1991, May 18-28 in 1992), when basal leaves
were present but before the hop shoots started climbing the twine; mid-season (June 14 in 1991,
June 8-23 in 1992), when shoots had twined 2-3 m up the twine; and pre-harvest (Aug 3, 1991;
Aug 17-18, 1992), when flowers had formed on side-arms growing from the main hop stem.
The hop leaves were observed under a binocular microscope at 10X; all life stages of phyto-
seiids were counted and adults were mounted in Hoyer’s solution on a microscope slide for
species identification. TSSM adult females were counted, and leaves were scored for damage
on a scale of 0 to 5 (O= no damage, |= light damage to one leaf lobe, 2= light damage to 2 lobes,
3= light damage to 3 or more lobes, 4= heavy damage to 3 or more lobes, and 5= heavy dam-
age over entire leaf surface).
Escaped hops survey
Several sites in the Willamette Valley were found with escaped, unsprayed hops. Typical
sites were in field headlands, road verges, and along ditches and fencerows. Most sites were near
commercial hops or other crops, which could harbor spider mites or predatory mites. Hop leaf
collections were made from 0-2 m; leaves with TSSM were selected where possible. In 1991,
14 samples of 50 leaves each were taken from July 9 to August 5 from 11 sites. In 1992, three
surveys of 25 leaves per sample were made on May 8 (13 sites), between June 8-18-(19 sites)
and on July 29 (16 sites). Adult female TSSM were counted and phytoseiids were counted and
identified.
Early Spring Survival study
A single field of the Perle variety of hops (Field #30 in the commercial fields survey), which
had large numbers of phytoseiids the previous fall, was selected in 1992. On March 16, before
the hop plants started growing (hop plants are perennial and die back every year), 4 bags of live
bean plants in vermiculite were leaned against poles. The bean plants had light infestations of
spider mites to attract phytoseiids; they were replaced with fresh plants on March 30, April 6 (2
extra bags were added to total 6), and April 13. On the latter two dates 35 and 50 hop leaves, re-
spectively, were also collected from new shoots. Hop leaves and bean plants were observed for
mites and the phytosetids were collected for identification.
Transect surveys
Two commercial hop fields were selected to monitor dispersal of TSSM and phytosetids
from adjacent crops (berries). Field #27 had strawberries upwind; field #33 had strawberries
downwind and caneberries upwind. At each hop/berry interface, 50 leaves were collected from
a transect running from 40 m within the berry field to 40 m within the hop field. Five leaves were
collected at each of 10 sites along the transect: at 0, 10, 20, 30, and 40 m from the interface.
Leaves from hop fields were collected from plants near support poles. Predators were counted
and each leaf scored for damage on the 0-5 scale described above. This procedure was repeated
three times in 1991, on the same dates that commercial fields were surveyed.
RESULTS AND DISCUSSION
Commercial fields survey
TSSMs were generally low in number in 1991, presumably due to the cool, wet weather that
prevailed (Table 1). In early-season, infestations were detected in 13 fields (38% of total) but
mean densities of females/leaf in infested fields and mean damage ratings on infested leaves of
infested fields were all low. Only two predator specimens, both Amblyseius fallacis (Garman),
were found in early-season. At mid-season, more fields had TSSMs, infested fields had more
mites/leaf, and damage was higher on infested leaves in infested fields (these figures are not sig-
nificant at P < .05 in 1991). Again, few predators were found (5 specimens). At preharvest,
most fields had TSSMs (97%), there were significantly higher (P < .05) densities in infested
fields, and damage was significantly higher (P < .05) with some leaves rating 5. TSSMs in four
fields exceeded 10/leaf (Table 2), levels high enough to cause economic damage (Jim Todd’,
48 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
pers. comm.). However, more predators were found at this time (Table 1); most were A. fallacis.
These predators mostly were found in three fields, with high concentrations in fields #24 and
#30 (Table 2).
In 1992, TSSMs were generally more dense than in 1991 (Table 1). Percent fields infested,
mean number of TSSMs, and mean damage levels on infested leaves in infested fields were all
higher in early- and mid-season. However, late-season samples were lower in all three cate-
gories than in 1991. This decline was probably due to spraying in response to perceived condi-
tions favourable for TSSM (1992 was warmer and dryer than 1991). By mid-season, two fields
had TSSM levels higher than 10/leaf, and a third had elevated levels in late-season (Table 2).
Eighteen of all 1992 samples had TSSM levels at 1-6 per leaf; all 71 other samples were below
1 TSSM/leaf. Thus despite early and mid-season TSSMs being significantly (P < .02) higher in
1992 than 1991, they posed no greater threat to the crop in 1992.
In both years, the most common phytoseiid collected in commercial hops was A. fallacis. It
was the only species found in late-season 1991. Typhlodromus pyri Scheuten was found in early
and mid-season, but was absent by late-season. Cultural practices such as spraying may be
detrimental to T. pyri which probably migrates into hops. M. occidentalis was not found in
1991, but it occurred in late-season, 1992. Its occurrence may have been related to the hot dry
weather of 1992 (Croft et al. 1990).
Table 3
Tetranychus urticae and phytoseiid mites found in escaped hop sites.
199] Early 92 Mid 92 Late 92
Samples 14 13 19 16
Sample n 50 25 25 25
Mites/sample 8.5 £2.07 12.0*26:20 25.60+6.37 31.10+8.90
Mites/leaf 24+ .07 48+ .15 1.04+ .14 Ws Wiis ys.
Phytoseiids/sample' 4.70+1.28 6.38+2.87 6.7442.27 ile ee) ws)
Amblyseius fallacis 2 4 2 2
Typhlodromus pyri 58 of) 32 31
Metaseiulus occidentalis 2 Mae 3
Amblyseius andersoni w! 7 D7, 4
Amblyseius exopodalis 3
Typhlodromus arboreus 2
Typhlodromus mahri 2
Typhlodromus caudiglans 2
Unknown phytoseiids’ 6 10 45 11
Total phytoseiids 74 83 128 ay)!
1 Means + SE.
2 Unknowns were immatures which are unidentifiable.
Table 4
Spring trapping of overwintered Amblyseius fallacis in field #30, 1992.
PHY TOSEUDS
DATE pots Females Males = Juveniles Eggs Bean Plant Condition
March 30 2 19 0 Dy Many Dry, some green
April 6 4 6 ] 0 Few Frosted, some green
April 13 6 0 0 0 0 Frosted, some green
April 20 5 0 0 0 0 Good, slightly dry
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 49
Phytoseiids increased in commercial hops from low (very low in 1991) to substantial by late-
season, especially in 1992 (Table 1). Despite the presence of some TSSM, predators were not
abundant in early- and mid-season (highest level was 3.65 +— 1.57 predators / field, or 0.073
predators / leaf). At pre-harvest, predators were abundant in only two of the fields in 1991 (Table
2), but were abundant in more fields in 1992. Of nine fields where TSSMs exceeded 5 mites/leaf
(Table 2), five had few predators (similar to other fields with low TSSM counts), while four had
some of the highest predator numbers sampled. This indicated that phytoseiids, when present
in commercial fields, may respond numerically to TSSM. Their ability to regulate TSSM prob-
ably depends on their timing of entry into hops.
Two fields in 1992 had very high levels of phytoseiids (Table 2). Although the cultural and
pesticide histories of these fields were examined, no consistent differences were found between
these fields and others which might explain the greater incidence of phytoseiids.
Escaped hops survey
Mite numbers were very low on escaped hops in 1991 (Table 3). This season was cool and
wet, which was not conducive to buildup of TSSM. 1992 was warmer and drier than 1991
though. TSSM numbers in 1992 started low and increased through to late-season, reaching a
mean density of 1.17+.36 mites/leaf. Although this was nearly 5-fold more than in 1991, it still
was a non-economic level of mites from a grower’s point of view. In none of the 1991 samples
did the TSSM adults exceed I/leaf. In 1992, the sample with the most TSSMs (excluding the
outlier) was 3.52/leaf. Thus it seems that favorable conditions for mites in 1992 resulted in in-
creased TSSM over 1991 but still below those that would be of economic concern if present in
commercial hops.
In both years the majority of predators found on escaped hops were T. pyri, which is a gen-
eralist feeder usually associated with rosaceous plants (Hadam et al. 1986). T. pyri may be a va-
grant on hops as a result of its association with other plant species, including wild blackberry or
other rosaceous plants. A. fallacis was infrequently found on escaped hops, although it was
common in commercial hops. Twenty-five M. occidentalis were found on escaped plants in
1992 but only 2 were found in 1991, possibly because this is a heat- and dry-adapted predator
(Croft et al., 1990) and 1992 was the hotter, drier year. Nearly all Amblyseius andersoni (Chant)
found in 1992 were from a single humid site near a river; A. andersoni 1s a humidity-adapted
predator (Messing & Croft, 1991). Otherwise its abundance was like that of A. fallacis. Other
species were found infrequently.
Thus it appears that biological control is occurring actively on escaped hops. TSSM numbers
from unsprayed sites compared favorably with those in commercial hops, in which mite con-
trol is largely brought about with pesticides. The low variation in mite numbers in escaped hops
(no high peaks) compared to commercial hops indicates that biological control of TSSM may
be effective and dependable.
There was a wide variation in the habitat and vegetation surrounding unsprayed hops, rang-
ing from dry in full sunshine with low floral diversity nearby (e.g. road verges) to humid and
shady with high floral diversity (e.g. forested areas next to fields). The incidence of phytoseiids
and TSSMs seemed unrelated to habitat, indicating that the habitat of a commercial field might
be suitable for biological control of TSSM by phytoseiids.
Early Spring Survival study.
Phytoseiids (A. fallacis) were active and out of diapause by March 30 (Table 4), before the
hop vines started growing. However, by April 13 no more were found on trap plants. Up to April
6 there was virtually no vegetation in the field, either weeds or hop vines, which is normal in
overwintering hop fields. The 1991/92 winter was very warm with no prolonged frost; it seems
likely that phytoseiids were active at times during the winter and early spring before plant
growth occurred, feeding upon TSSM. Since there was no green matter present for spider mites
to feed on, the phytoseiids may have overexploited TSSM and then starved.
Early hop leaf collections contained two A. fallacis females, one juvenile and several eggs
found on April 6, a single female on April 13, and no predators on April 20. A few TSSMs were
found on the hop leaves from April 13 and 20; any predators present would probably have been
50 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
. Field #27 Strawberry
ae i Tssm_
ME Phytoseiids
b. Field #33a Strawberry
~— Prevallingwind
a
Number of TSSM or phytoseiids
~<«——— Distance from Interface (nm) ———>
Figure 1. Levels of Tetranychus urticae (TSSM) and phytoseiid mites (Amblyseius fallacis, Typhlodro-
mus pyri) found in mid-season transect surveys of hop yards and adjacent crops, 1991 (lines are SE’s).
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 a1
associated with these TSSMs. It appears that although the phytoseiids overwintered success-
fully, hop plants may become active too late to support the early spider mite colonies required
for early spring survival of phytoseiids .
Transect surveys
A general trend was noted that TSSMs often were present in crops surrounding hops at higher
levels than in hops in early-season and that they dispersed into the hops as the season pro-
gressed. Three examples of this are presented in Figure 1, all of which are from the mid-season
sample period. In Field #27, no TSSM were found in hops in early-season despite levels in the
adjacent strawberries of .24 TSSM/leaf, but by mid-season an edge effect was apparent (Figure
la). Possibly the TSSM moved into the hops on prevailing winds; both TSSM and phytoseiids
are capable of dispersing on wind (Johnson & Croft, 1976; Kennedy & Smitley, 1985; Sabelis
& Dicke, 1985). As the season progressed, this apparent edge effect diminished. In contrast,
field #33a had a prevailing wind blowing the opposite way. Again, in early-season there were
neither TSSM nor phytoseiids in the hops; by mid-season there was an apparent edge effect but
at much lower numbers than Field #27 (Figure 1b). Also, the abundant phytosetids in strawberry
never moved over into hops, despite being the highly dispersive species, A. fallacis (Johnson &
Croft, 1976). The data from Field #33b indicate that the species of phytoseiid is also important
in dispersal (Figure 1c). Despite prevailing winds from the caneberries to the hops, phytoseiids
were not detected in the hops. The phytoseiid found in the caneberries was exclusively T. pyri,
which is known to be a relatively poor disperser (Boller et al., 1988; Croft et al., 1990).
Apparently both spider mites and predators overwinter well in surrounding crops but poorly
in hops; they then disperse into hops at rates depending on species, prevailing wind direction,
and possibly other factors. Although the data in Figure 1 are from limited sites and show con-
siderable variability, they indicate the need for further investigation into early-season movement
of predators and TSSM in relation to surrounding crops and prevailing wind direction.
CONCLUSIONS
It appears that despite intensive spraying, TSSMs and damage from these pests increase sea-
sonally in most commercial hop fields. In six fields at pre-harvest, TSSMs exceeded 10 per leaf,
a large proportion of leaves had mites, and damage ratings were high. Although economic im-
pact of these TSSM levels needs more definitive research, an alternative management method
to pesticides is desirable.
Presumably biological control of TSSM using phytoseiids would be possible in hops except
for 3 conditions: limited ability of phytoseiids to establish populations in the early spring, their
lack of early-season dispersal into hops, and use of pesticides and cultural practices harmful to
predators. The differential early-spring survivorship of phytoseiids and TSSM makes hops sim-
ilar to a perennial crop for TSSM, but more like an annual crop for phytoseiids. With their low
dispersal rates into hop fields from surrounding crops, phytoseiids may need re-introduction
each year. This was the conclusion of Cranham (1985) who felt that stable biological control in
hops was unlikey due to the annual nature of the crop.
Use of some cultural practices and insecticides in hop culture are difficult to avoid, but oth-
ers may be modified. Planting ground covers favorable to survival of phytoseiids, and elimi-
nating leaf stripping and hilling around hops, both of which remove leaves haboring phytosei-
ids early in spring may be helpful. Pesticide changes may include eliminating pyrethroids and
using insecticides more compatible with phytoseiids (Croft 1990). However, even with these
modifications, the early spring pool of phytoseiids may be too small to ensure biological con-
trol and thus supplementary releases may be required.
Supplementary releases would be most economical when used in an inoculative manner.
From these studies, the key time to release would be early spring, when TSSM start to develop
but naturally-occurring phytoseiids are rare. The number of releases, release location (within
and between plants) and release density of phytoseiids have yet to be determined. The results
of this study indicate that four species should be tried: T. pyri and A. andersoni, found mostly
on escaped hops; M. occidentalis, found on both escaped and commercial hops; and A. fallacis,
52 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
found mostly in commercial hops. The other phytoseiids collected in this study were probably
incidentals and unlikely to play a major role in biological control. It is likely that A. fallacis and
M. occidentalis will have the greatest commercial impact, since they were the only species that
were abundant in commercial hops. A mixture of both species might be advisable. The micro-
habitat on a hop plant may vary from cool and humid (suitable for A. fallacis) at the bottom to
warm and dry (suitable for M. occidentalis) near the top. Moreover, since future weather con-
ditions at the time of release are unpredictable, releasing both species might ensure control re-
gardless of weather conditions.
NOTE
1. Jim Todd, Willamette Agricultural Consulting, 7555 Conifer St NE, Salem, OR 97301.
REFERENCES CITED
Boller, E. F., U. Remund and M. P. Candolfi. 1988. Hedges as potential sources of Typhlodromus pyri, the most impor-
tant predatory mite in vineyards of northern Switzerland. Entomophaga 33(2): 249-255.
Campbell, C. A. M. 1985. Hops (Humulus lupulus). In N. W. Hussey and N. Scopes. Biological Pest Control: the
Glasshouse Experience. Ithica, NY, Cornell University Press. 192-194.
Cone, W. W., L. C. Wright and T. E. Wildman. 1986. Reproduction by overwintered Tetranychus urticae (Acari:
Tetranychidae) on hops. Ann. Entomol. Soc. Am. 79: 837-840.
Cranham, J. E. 1985. Hop. In W. Helle and M. W. Sabelis. Spider Mites: their Biology, Natural Enemies, and Control,
Vol. 1B. New York, Elsevier. 367-370.
Croft, B.A. 1990. Arthropod Biological Control Agents & Pesticides. Wiley Intersci. J. Wiley, N.Y. 723 pp.
Croft, B. A., P. Shearer, G. J. Fields and H. W. Riedl. 1990. Distribution of Metaseiulus occidentalis (Nesbitt) and Ty-
phlodromus pyri Scheuten (Parasitiformes: Phytoseiidae) in apple orchards of the Hood River Valley, Oregon. Can.
Entomol. 122: 5-14.
Hadam, J. J., M. T. Aliniazee and B. A. Croft. 1986. Phytoseiid mites (Parasitiformes: Phytoseiidae) of major crops in
Willamette Valley, Oregon, and pesticide resistance in Typhlodromus pyri Scheuten. Environ. Entomol. 15: 1255-
1263:
Johnson, D. T. and B. A. Croft. 1976. Laboratory study of the dispersal behavior of Amblyseius fallacis (Acarina: Phy-
tose1idae). Ann. Ent. Soc. Am. 69(6): 1019-1023.
Kennedy, G. G. and D. R. Smitley. 1985. Dispersal. In W. Helle and M. W. Sabelis. Spider Mites: their Biology, Nat-
ural Enemies and Control Vol. 1A. New York, Elsevier. 233-242.
Messing, R. H. and B. A. Croft. 1991. Biosystematics of Amblyseius andersoni and A. potentillae (Acarina: Phytosei-
idae): Implications for biological control. Exp. Appl. Acarol. 10: 267-278.
Pruszynski, S. and W. W. Cone. 1972. Relationships between Phytoseiulus persimilis and other enemies of the twospot-
ted spider mite on hops. Environ. Entomol. 1(4): 431-433.
Pruszynski, S. and W. W. Cone. 1973. Biological observations of Typhlodromus occidentalis (Acarina: Phytoseiidae)
on hops. Ann. Ent. Soc. Am. 66(1): 47-51.
Sabelis, M. W. and M. Dicke. 1985. Long-range dispersal and searching behaviour. In W. Helle and M. W. Sabelis. Spi-
der Mites: their Biology, Natural Enemies, and Control Vol. 1B. New York, Elsevier. 141-160.
Sites, R. W. and W. W. Cone. 1985. Vertical dispersion of twospotted spider mites on hops throughout the growing sea-
son. J. Entomol. Soc. Brit. Columbia 82: 22-25.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 53
Relationships between catches in flight and
emergence traps of the mountain pine beetle,
Dendroctonus ponderosae Hopk. (Col.: Scolytidae)
L. SAFRANYIK and D.A. LINTON
FORESTRY CANADA, PACIFIC FORESTRY CENTRE, 506 WEST BURNSIDE ROAD,
VICTORIA,B.C., V8Z 1M5
ABSTRACT
Daily emergence of the mountain pine beetle from lodgepole pine trees was monitored in the
field by using caged bolts and by counting emergence holes on standing trees. Flying mountain
pine beetles, pine engraver beetles and Pityogenes plagiatus knechteli (Swaine) were captured
daily in two types of barrier traps. Daily totals of emergence holes and emergence into cages
were moderately correlated with daily captures by both types of barrier traps. A simple model
of daily emergence was developed based on estimates of brood density, daily proportions of
brood adults, and daily proportions of brood adults ready to emerge. Daily catches of pine en-
gravers and P. plagiatus knechteli were highly intercorrelated, but correlations with catches of
mountain pine beetle were low for both species. The results are discussed in relation to beetle
emergence and flight behaviour.
INTRODUCTION
The onset and timing of the emergence of mountain pine beetles, Dendroctonus ponderosae
Hopkins or mpb, depend on a number of factors. In combination, the distribution in time of at-
tacks by the parent beetles and accumulation of heat above the temperature threshold for de-
velopment (Bentz et al. 1991, Safranyik 1978, Safranyik and Whitney 1985), are the major de-
terminants of the life-stage distribution of broods. Moisture conditions during adult maturation
are also important because new adults need a period of feeding of up to 10 days (more during
cool, rainy weather). Mature beetles begin emerging when ambient temperatures reach about
16°C (Reid 1962, Schmid 1972, Billings and Gara 1975) and the emergence rate increases with
temperature up to about 30°C (Rasmussen 1974). Above 30°C, both hourly and daily emer-
gence decline. As a consequence of these relationships, once emergence has started, and the age
structure and density of broods are known, the diurnal pattern of emergence during the flight pe-
riod (i.e., relative frequencies of emerged beetles per unit of time during the day) can be pre-
dicted based on heat accumulation above the temperature threshold for emergence (Safranyik
et al 1989).
Traps or host materials are often used to monitor bark beetle emergence and flight activity,
sometimes in combination with population aggregation pheromones. Trapping can provide rel-
ative measures of populations or expected damage levels (Brown 1977, Lie and Bakke 1981,
Hiibertz et al 1991). A variety of trap types have been used for trapping the beetles, both when
flying (e.g. barrier and funnel traps, sweep nets) and emerging (e.g. emergence cages, sleeve
traps) (Chapman and Kinghorn 1955, Avis 1971, Hines and Heikkenen 1977, Hosking 1979,
Lindgren 1983, Schmitz 1984, Safranyik and Linton 1985). Emergence holes may also be
counted to monitor daily or seasonal emergence.
A high positive correlation between the number of beetles emerging and numbers flying in a
given period is implicit in the use of flight traps for monitoring emergence or population levels.
Spatial and temporal variations in emergence behaviour are common results of differences in at-
tack history, tree and site conditions, weather factors, and the distribution and abundance of suit-
able host materials. The design, density, and deployment (location and timing) of traps are im-
portant factors affecting the strength of the association between trap catches and emergence or
population levels.
The objectives of this study were to:
a) describe the relationship between daily captures of flying mpb in passive barrier traps and
daily emergence from caged bolts;
54 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
b) develop an empirical model of mpb emergence density based on temperature, pre-emer-
gence density and age structure of broods;
c) relate the emergence pattern of two common associates of mpb, /ps pini (Swaine) (pine en-
graver beetle or peb), and Pityogenes plagiatus knechteli (Swaine) (ppk) to temperature and
the emergence pattern of mpb.
The results and discussion concentrate on mpb, as it is the primary pest species. Peb and ppk
are normally secondary attackers, usually incapable of successfully attacking a healthy host.
They normally infest mpb attacked trees, or trees weakened by some other agent.
MATERIALS AND METHODS
The study area was located approximately 100 kilometers west of Williams Lake, B.C., near
Tsuh Lake. The site was generally flat, uniformly forested, 5.86 ha in area, with about 2 ha. of
2-3m high esker-like ridges in the southeast portion. Within the stand were three groups of 15-
20 mature lodgepole pine Pinus contorta var. latifolia Dougl. attacked in 1984 and containing
brood mpb which would mature and emerge in the summer of 1985. The three groups occupied
the corners of a triangle of about 100 m per side. The study area was surrounded on three sides
by open meadows 10-40 m wide, and on the fourth side by an immature (<40 yr. old) lodgepole
pine stand containing a few veteran Douglas-fir (Pseudotsuga menziesii (Mirb.)Franco). Within
the study area, the tree cover averaged 592.3 stems 25 cm dbh per ha, which consisted of 83%
lodgepole pine, 11% engelmann spruce (Picea engelmannii Parry)(mainly in depressions), and
the balance scattered Douglas-fir and aspen (Populus tremuloides Michx.). The average age of
the pine in 1985 was 102 years with an average DBH of 25.02cm. All trap installations were
completed by the last week of June 1985.
Two types of passive (unbaited) barrier traps were used. Six pairs of nondirectional traps
were hung from uninfested pine trees at 60° intervals surrounding each group of infested trees.
These were similar to traps described in Schmitz et al (1980), and had four 15X30 cm barriers
at right angles to each other above a funnel leading to a single collecting jar. They were sus-
pended from ropes so that the bottoms of the barriers were 2 m above the ground. In addition,
four larger (90X 150cm) unidirectional traps were hung in the approximate center of each group
of infested trees. These large traps were suspended from poles between trees in such a way that
one trap in each group faced each cardinal direction, and would thus capture insects flying from
that direction. The lower edges of the large barriers were also 2 m above the ground.
One bolt, 35 cm long, was cut from the base of each of six pines infested in 1984. The bolts
were then placed in individual window screen emergence cages placed near the stumps from
which the bolts were cut in order to observe daily emergence of mpb. The 35 cm bolt length cor-
responded to the depth of the previous winter’s snow; above that virtually all of the mpb were
killed during the winter (the mean maximum height at which live larvae were found was 53 cm
(Safranyik and Linton 1991)).
A .5 m wide band extending from the duff line to the height of the estimated snow depth dur-
ing the previous winter on each of four 1984 infested trees in one group was painted with light-
colored latex paint to enhance the visibility of newly-made exit holes (Safranyik and Linton
1985). In order to exclude them from the 1985 counts, all existing exit/entrance holes were
marked before 1985 emergence began. Three times during the flight period, 15X15 cm bark
samples were removed from eighteen 1984 infested trees and the brood examined to determine
Stage of maturity.
Insects were collected from all traps and new exit holes through the painted bands were
counted and marked each morning from July 09 to August 10, and on August 12. The collec-
tions were preserved in 70% alcohol and stored until examined and counted. In the lab, the to-
tal captures of mpb, peb and ppk were recorded, and their sex determined.
Air temperatures were obtained using Campbell Scientific Instruments Ltd. model 201 ther-
mistor sensors mounted in Stevenson screens. Underbark temperatures were taken using ther-
mocouples inserted under the bark of the caged bolts. Data were recorded on a Campbell Sci-
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 55
entific Instruments Ltd. CR-21 data logger having a ten second scan rate, outputting summary
statistics every 30 minutes. Degree-days were calculated by counting the number of hours when
the air temperature exceeded 16°C and dividing the sum by 24.
The relationship between catches of beetles in flight traps and emergence traps was analysed
using regression and correlation analysis. A general model of daily mpb emergence was devel-
oped based on attack and emergence behaviour, and the effects of temperature on maturation,
emergence and flight activity. Model parameters were estimated from field data.
RESULTS AND DISCUSSION
A model of beetle emergence
The following empirical model for daily emergence (E;,) is based on estimates of pre-emer-
gence brood density (D), daily proportions of the unemerged brood that are mature (tanned)
adults (P;.), and daily proportions of the mature brood adults ready to emerge (Q;,). The fol-
lowing is a brief description of model development. For the Ist, 2nd and 3rd days of emer-
gence, the corresponding numbers of emerged beetles (Ej_ | 3) are given by the series DP} Q),
(D-DP}Q))P5Q5, and (D-DP}Q)(D-DP ; Q; )P7Q>)P3Q3, respectively. It can be shown that
these series can be written in the following equivalent forms to express emergence on any given
day K in terms of D, P and Q.
k-1
E,=D[ » (1-P;Q;)]P,. Qu. (la)
1=0
k-1
E,=(D- 2 E;)P, Q. (1b)
i=]
Equation (1b) is more transparent since it is readily seen that EF; is simply the product of un-
emerged brood density (the terms inside the brackets) and the values of P and Q for day K fol-
lowing the onset of beetle emergence. An empirical formula was developed for estimating P,
(P,) as a function of time (T) in days since the first occurrence of young adults (assumed to be
July 1), based on sampling 18 infested trees 3 times during the study period. P, was a hump-
backed function on T in the experimental area because some parent beetles that survived the
winter extended their galleries and laid more eggs in late May-early June of 1985 which resulted
in a highly skewed brood age distribution. Consequently, as the brood resulting from eggs laid
in 1984 matured and emerged, the young larvae from eggs laid in the spring of the current year
constituted the bulk of the unemerged broods. Hence, Py, at first increased on T and later de-
clined. When mpb flight is not protracted and all eggs hatch before the onset of winter the rela-
tionship curve between P,, and T is sigmoid (Bentz et al 1991). Equation (2) was developed by
plotting both the mean of P, and the mean proportion of 1984 broods (Z) over the correspond-
ing T-values for each of the three sampling times. A sigmoid curve (Bentz et al 1991) was fit-
ted by eye to the P, vs T relationship (the expression inside the first set of square brackets on
the right side of eqn (2)) and the parameters were determined by graphical analysis. The ex-
pression inside the second set of square brackets on the right hand side of eqn (2), also fitted by
graphical analysis, represents the relationship between z and t.
pk=[(0.0131)/(0.01+0.99 exp(-0.28t))][1-exp(-5.36+0.16t)] (2)
t>33, p,=0
q, was estimated (qj,) as a function of daily degree-days (hy) above a threshold of 16°c:
Qk=(1/6)hy, hy, <6
qk=1 , hb (3)
This formula was used for simplicity, recognizing that most mature adults emerged when
daily maximum temperatures were near or above 25°c.
56 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
Observed no. emergence holes per day
0 10 20 30
Predicted no. emergence holes per day
Observed no. beetles emerged per day
0 10 20 30 40
Predicted no. beetles emerged per day
Figure 1. Relationship between observed daily accumulation of emergence holes (A) and beetle emer-
gence (B) for the mountain pine beetle and predicted density from eqn. 1. Estimates of Qk in eqn. 1 were
based on ambient temperature data from Tsuh Lake 1985.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 5.
The numbers of beetles (720) under the bark of 6 caged trees (lower boles, total bark area 4.05
m/) and the number of emergence holes (362) on the painted areas of 4 trees were used as esti-
mates of D in conjunction with eqns (2) and (3) to model daily emergence and daily accumula-
tions of emergence holes (E;,) during 23-days from July 9 to July 31, inclusive. Both ambient
and underbark temperatures were used in eqn (3) to model emergence. Estimates of E, from
eqn. 1 were regressed on corresponding observed E;.-values (regression was conditioned to
have 0 intercept) to assess the performance of the model (Fig. 1). The slopes (b) of regressions
of observed vs predicted daily counts of emerged beetles were comparable and were not signif-
icantly different from unity (p>0.05) when either ambient (b=1.056) or underbark temperatures
(b=1.042) were used in calculating Q,; in eqn 2. The corresponding coefficients of determina-
tion (r°) were 0.685 and 0.638. The corresponding statistics for predicting daily accumulations
of emergence holes were (b=1.107 and 1.132) and (’=0.781 and 0.787). The fit of the model to
the daily beetle emergence and emergence hole data is satisfactory considering that P was esti-
mated from observation of beetle maturation only on three occasions and a limited number of
samples, and that the formula for Q (eqn. 3) was derived from conceptual relations between heat
accumulation and beetle emergence. However, in addition to these factors, the variation be-
tween observed and predicted values in Fig. | could have been affected by formulation of the
model. In particular, in eqn 1, the fate of those mature beetles that did not emerge in any given
day owing to inadequate heat accumulation (as estimated by eqn 3) is not considered explicitly.
Therefore, even if Q was modelled very precisely, eqn 1 would tend to underestimate daily bee-
tle emergence, especially following days for which the value of Q was less than 1. This prob-
lem of model formulation needs further research.
Comparison of mpb emergence, trap catches and trap types
Daily emergence of mpb/m’ of bark from caged trees (Y,.), daily catches/m’ of trap area in
large barrier traps (Y,) and smaller barrier (flight) traps (Y¢), were all linearly related to daily
emergence hole numbers per m’ (X) on the painted trees. The respective equations were as fol-
lows:
Y (=0.1507+0.4155X (4)
n=26, r=0.693, Syx=2.540
Y 9=0.4275+0.0148X (5)
n=22, r=0.090, Syx=0.426
Y ¢=0.5031+0.0580X (6)
n=26, r=0.239, Syx=0.670
Y ¢=0.0619+0.1935 Y. (7)
n=25; 1 —0.155, oyx—0-2 15
Regression eqns (4), (6) and (7) were statistically significant; the first two at the 99% and the
third at the 95% probability level. However, with the exception of eqn (4), only up to about 24%
of the total variation in the respective independant variables was explained by the regression
equations. The intercepts of regressions (5) and (6) were significantly different from 0 at the
99% and 95% probability levels, respectively.
Excluding variation in daily counts of emergence holes and emerged beetles due to experi-
mental techniques, these two variables are normally highly correlated but have a non-linear re-
lationship (Safranyik and Linton 1985). However, when they were measured on different sam-
ples, as was done in our experiment, differences in host characteristics, attack history and
microclimate were reflected in different rates of beetle emergence among infested hosts. The re-
liability of emergence hole counts may be affected by the presence of holes made by other
species of subcortical insects. Moreover because of differences in underbark and ambient tem-
peratures, the beetles may cut emergence holes up to several days before they emerge. For these
reasons, when measured on small and separate samples, the densities of emerged beetles and
emergence holes will normally have only moderate correlation.
Emerged beetles may disperse over large areas and search for suitable hosts to attack. Con-
58 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
a
- | Acne Mean daily
° ae
temp. ~
ey cs
10
Temperature (°C) and no.
Dendroctonus ponderosae trapped
capture
0 10 20 30
July 8 Days of capture Aug 8
Figure 2. Mean daily temperature and daily capture of mountain pine beetle in passive barrier traps, Tsuh
Lake, 1985.
600
500
a 400 ae -
‘a 2
= Meéan =
£ 300 daily’: 5
a se : temp. <.." =
od
S =
100
0
0 10 20 30
July 8 Days of capture Aug 8
Figure 3. Mean daily temperature and daily capture of pine engraver beetles in passive barrier traps, Tsuh
Lake, 1985.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 59
sequently, it is likely that most passive barrier traps sample the beetle population of a large area.
Therefore, unless emergence or emergence holes were monitored over the same general area
and sampling intensity was high, passive trap catches may be poorly correlated with these vari-
ables.
Although the experiments spanned 22-26 days of observation, the samples for beetle emer-
gence and emergence holes were based on only 6 bolts and 4 trees, 36 small barrier traps (eqn
6) and 12 large barrier traps (eqn 5). These small sample sizes notwithstanding, the correlations
between daily emergence holes and trap catches were unexpectedly low (eqns 5 and 6). Fur-
ther studies are needed to determine whether catches in passive barrier traps should be used for
monitoring beetle emergence. Likewise, the low correlation between catches in the two types
of barrier traps (eqn 7) indicate that results from experiments using different trap designs may
not be directly comparable.
Emergence and flight of mpb, peb and ppk.
During the study, 194 mpb, 681 peb and 1171 ppk were trapped. Daily capture of mpb (Fig.
2), peb (Fig. 3) and ppk (Fig. 4) during a 37-day period varied with average temperatures (Fig.
2). The greatest catches of all three species occurred following a period when average daily tem-
perature was greater than 20°C for at least 3 consecutive days (Fig. 2). Daily maximum tem-
peratures during the same period ranged from 31.8 to 34.3°C. Catches of mpb were broadly dis-
tributed throughout the observation period whereas catches of the other two species peaked
sharply on July 15, a day later than peak mpb catch, and then declined (Figs. 2-4). Daily catches
of ppk and peb were highly correlated (r=0.89, N=25). On the other hand, the correlation be-
tween daily catches of ppk and mpb was not significant (r=0.31, N=25) and that between peb
and mpb was barely significant at p<0.05 (r=.40, N=25). The asynchrony of catches of mpb and
the other two species is probably a consequence of differences among the species in emergence
and flight in relation to temperature. For mpb, daily degree-day accumulation above a thresh-
old temperature of 16°C was not significantly correlated (p>0.05) with daily trap catches
(r=0.30, n=25), daily emergence from caged bolts (r=0.10, n=25) or with daily accumulation of
100
Temperature (°C)
No. Pityogenes plagiatus knechteli trapped
Ol
©
0 10 20 30
July 8 Days of capture Aug 8
Figure 4. Mean daily temperature and daily capture of Pityogenes plagiatus knechteli in passive barrier
traps, Tsuh Lake, 1985.
60 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
emergence holes on sample trees (r=0.35, n=25). There is no information on the other species
regarding temperature thresholds and heat unit requirements for emergence and flight activity.
In British Columbia, particularly in the Cariboo region, peb produces 1 or 2 generations per
year, depending on spring and summer temperatures. The first flight, made by overwintering
adults emerging from the duff normally occurs during May and early June, and the second
flight, made by reemerging parents plus their brood normally occurs during July-August (Reid
1955). Therefore, the beetles trapped in our experiments were mostly reemerged and first gen-
eration beetles. Ppk overwinters both in adult and immature stages (Reid 1955). It appears that
during the experimental period, most of the dispersing mature adult pine engravers and ppk
originated from broods of parents that overwintered in the adult stage. The mpb trapped were
part of the main flight of brood adults that developed in a 1-year life cycle.
The overall female ratio (+ one standard deviation) was 0.68 (+0.05 1) for mpb, 0.76 (+0.041)
for peb and 0.91 (+0.069) for ppk. These ratios did not change significantly during the study pe-
riod. There was no significant difference (p>0.05) between the female ratios for mpb and peb
from those reported from field populations (0.67 for mpb (Reid 1962, Safranyik and Whitney
1985; 0.75 for Ips pini (Schmitz 1972)). There is no sex ratio information available for ppk. Ppk
is, however, polygamous and 3 to 10 females may be associated with one male in gallery sys-
tems (Chamberlin 1958). Reid (1955) reported 4-6 egg galleries associated with one nuptial
chamber in lodgepole pine slash in Alberta.
Our results indicate that daily rates of mpb emergence can be reliably modelled based on es-
timates of pre-emergence density, age structure, and daily heat accumulation above the flight
threshold temperature. Sample-based estimates of mpb emergence hole densities are highly
correlated with corresponding estimates of beetle emergence, indicating that the estimate are a
reliable index. However, sample-based daily estimates of both these variables were poorly cor-
related with daily catches in passive barrier traps. Therefore, daily emergence patterns of mpb
cannot be reliably inferred from daily captures in passive barrier traps. Daily flights of mpb, peb
and ppk are all closely related to daily mean temperature; daily flights of the latter two species
are highly correlated.
ACKNOWLEDGEMENTS
The authors thank Drs. H. Barclay, T. Sahota, and T. Thompson, Forestry Canada, Pacific
Forestry Centre, for their reviews of the manuscript.
LITERATURE |
Avis, R.W. 1971. Flight and attack patterns. The mountain pine beetle, Dendroctonus ponderosae Hopk., (Coleoptera:
Scolytidae). Vancouver, B.C.: University of British Columbia: 1971. 58pp. MLS. thesis.
Bentz, B.J., J.A. Logan and G.D. Amman. 1991. Temperature dependant development of the mountain pine beetle
(Coleoptera: Scolytidae) and simulation of its phenology. Can. Ent. 123:1083-1094.
Billings, R.F.,, and R.I.Gara. 1975. Rhythmic emergence of Dendroctonus ponderosae (Coleoptera: Scolytidae) from
two host species. Ann. Entomol. Soc. Amer. 68:1033-1036
Brown, L.E. 1977. A trapping system for the western pine beetle using attractive pheromones. J. Chem. Ecol. 4:261-
2795.
Chamberlin, W.J. 1958. The scolytidae of the Northwest. Oregon, Washington, Idaho and British Columbia. Oregon
State Monographs Number 2. Ore. St. Coll., Corvallis, Oregon. 205pp.
Chapman, J.A., J.M. Kinghorn. 1955. Window flight traps for insects. Can. Ent. 87: 46-47.
Hines, J.W. and H.J. Heikkenen. 1977. Beetles attracted to severed Virginia pine (Pinus virginiana Mill.). Environ. En-
tomol. 6: 123-127.
Hosking, G.P. 1979. Trap comparison in capture of flying Coleoptera. N.Z. Entomology 7:87-92.
Hiibertz, H., J.R. Larsen and B. Bejer. 1991. Monitoring spruce bark beetle (/ps typographus) populations under non-
epidemic conditions. Scand J. For. Res. 6:217-226
Lie, R. and A. Bakke. 1981. Practical results from mass trapping of Ips typographus in Scandinavia. PP175-181 in E.R.
Mitchell (Ed.) Management of insects with semiochemicals: concepts and practice. Plenum Press New York and
London. 514 pp.
Lindgren, B.S. 1983. A multiple funnel trap for scolytid beetles (Coleoptera). Can. Ent. 115:299-302.
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Rasmussen, L.A. 1974. Flight and attack behaviour of mountain pine beetles in lodgepole pine of northern Utah and
southern Idaho. USDA Forest Serv. Res. Note INT-180. Intermtn. For. and Range Exp. Sta., Ogden, UT. 7pp.
Reid, R.W. 1955. The bark beetle complex associated with lodgepole pine slash in Alberta. Can. Ent. 87:311-323.
Reid, R.W., 1962, Biology of the mountain pine beetle, Dendroctonus monticolae Hopkins, in the East Kootenay Re-
gion of British Columbia. I. Life cycle, brood development and flight periods. Can. Entomol. 94:531-538.
Safranyik, L. 1978. Effects of climate and weather on mountain pine beetle populations. /n D.L. Kibbee, G.D. Amman,
A.A. Berryman and R.W. Stark, eds. Theory and practice of mountain pine beetle management in lodgepole pine
forests. Symposium Proceedings Wash. State Univ. Pullman, WA April 25-27, 1978 274pp.
Safranyik, L., and D.A. Linton. 1985. The relationship between density of emerged Dendroctonus ponderosae
(Coleoptera:Scolytidae) and density of exit holes in lodgepole pine. Can. Ent. 117:267-275.
Safranyik, L. and D.A.Linton. 1991. Unseasonably low fall and winter temperatures affecting mountain pine beetle and
pine engraver beetle populations and damage in the British Columbia Chilcotin region. J. Entonol. Soc. Brit. Co-
lumbia 88:17-21.
Safranyik, L. Silversides, R.H., McMullen, L.H., Linton, D.A. 1989. An Empirical approach to modelling the disper-
sal of the mountain pine beetle (Dendroctonus ponderosae Hopk,)(Col., Scolytidae) in relation to sources of at-
traction, wind direction and speed. J. Appl. Ent. 108:948-511.
Safranyik. L., and H.S.Whitney. 1985. Development and survival of axenically reared mountain pine beetles at constant
temperatures. Can. Ent. 117:185-192.
Schmid, J.M. 1972. Emergence, attack densities and seasonal trends of mountain pine beetle (Dendroctonus pon-
derosae) in the Black Hills. USDA For. Serv. Res. Note RM-211. Rocky Mtn. For. and Range Expt. Sta., Ft. Collins,
CO. 7pp.
Schmitz, R.F. 1972. Behaviour of [ps pini during mating, oviposition, and larval development (Coleoptera:Scolytidae).
Can. Ent. 104:1723-1728.
Schmitz, R.F. 1984. A passive aerial barrier trap suitable for sampling flying bark beetles. USDA Forest Service Inter-
mountain Forest and Range Expt. Sta. Res. Note INT-348. 8pp.
Schmitz, R.F., M.D. McGregor and G.D. Amman. 1980. Mountain pine beetle response to lodgepole pine stands of dif-
ferent characteristics. PP234-243 in A.A. Berryman and L. Safranyik [Eds.]. Dispersal of forest insects: evaluation,
theory and management implications. Proc. IUFRO Symposium, Aug. 27-31, 1979. Pullman, WA. p278.
Effects of female mating status and age on
fecundity, longevity and sex ratio in Trichogramma minutum
(Hymenoptera: Trichogrammatidae)
LI, S.Y., G. SIROIS, D.L. LEE, C. MAURICE and D.E. HENDERSON
E. S. CROPCONSULT LIMITED, 3041 WEST 33RD AVENUE, VANCOUVER, B. C., CANADA VON 2G6
ABSTRACT
Effects of female mating status and age of Trichogramma minutum Riley on its fecundity,
longevity and offspring sex ratio were determined in the laboratory, using eggs of the variegated
cutworm as hosts. Although the mating status of female 7: minutum did not affect their total fe-
cundity significantly (P > 0.05), mated and unmated females showed different allocations of
progeny. Mated females deposited significantly more eggs (P < 0.05) than those unmated on the
first day of exposure to hosts. On subsequent days, however, unmated females parasitized sig-
nificantly more hosts (P < 0.05) than those mated. Mated females laid 82.4% of their total fe-
cundity on the first day of oviposition, whereas unmated females laid 58.3%. The number of
eggs parasitized by both groups of females decreased significantly (P < 0.05) with parasitoid
age. Unmated females lived longer (P < 0.05) than their mated counterparts. No significant dif-
ferences (P > 0.05) in clutch size (the number of parasitoid offspring produced per parasitized
host) and emergence rate were found between the offspring of mated and unmated female par-
asitoids. The sex ratio of the offspring of mated females changed significantly (P < 0.05) with
maternal age: younger females produced a higher proportion of daughters than did older para-
sitoids. Unmated females produced male offspring only.
62 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
INTRODUCTION
The effects of host size (Stinner et al. 1974; Southard et al. 1982; Bai et al. 1992), rearing
temperatures (Smith and Hubbes 1986; Jalali and Singh 1992), and food availability to females
(Bai et al. 1992) upon reproductive potential of Trichogramma have been well documented.
However, maternal mating status and age may influence longevity, fecundity and sex allocation
in Trichogramma. Although Partridge (1986) reported that mated females of insects are gener-
ally shorter lived than virgins, the effect of maternal mating on reproductive potential of Tri-
chogramma remains uncertain. Lund (1938) observed that there were no differences in
longevity between mated and unmated females of Trichogramma evanescens Westwood, but
there was a significant difference in fecundity. In contrast, Yu et al. (1984) found that longevity
in mated and unmated Trichogramma minutum Riley differed significantly, but there was no
significant difference in fecundity.
Reduced fecundity with maternal age has been documented in various insect species. How-
ever, a recent study by Navasero and Elzen (1992) demonstrated that the clutch size in mated
Microplitis croceipes (Cresson) (Hymenoptera: Braconidae) varied cyclically over their life
spans with egg production peaking in intermediately-aged parasitoids. Previous studies have
shown that offspring sex ratio in Trichogramma is affected by maternal age. In studies on T.
minutum, Houseweart et al. (1983) and Smith and Hubbes (1986) both reported that young fe-
males produced a higher proportion of female offspring than old females.
Although reproductive biology of 7. minutum associated with other hosts has been studied
(Yu et al. 1984; Smith and Hubbes 1986), no reports have been documented on this species with
the variegated cutworm, Peridroma saucia (Hiibner), a minor pest on field crops in British Co-
lumbia. In recent years, however, P. saucia becomes more and more abundant on small fruit
crops. An ongoing field release of Trichogramma to control P. saucia on raspberry is currently
conducting in the Fraser Valley (Henderson et al. unpub. data). The reproductive characteristics
of commercial T. minutum with P. saucia may be different from that of field collected parasitoids
with other hosts studied by others (Yu et al. 1984). The objectives of this study were to investi-
gate the effects of female mating status on progeny allocation, longevity and fecundity in a
commercial strain of T. minutum; and to determine sex allocation over the lifespan of mated fe-
male T. minutum, using eggs of P. saucia as hosts.
MATERIALS AND METHODS
Host eggs.
The host eggs used in this study were obtained from a laboratory culture of P. saucia and were
less than 24 h old.
Parasitoids.
Trichogramma minutum was obtained from a commercial source, reared on eggs of the
Mediterranean flour moth, Ephestia ( = Anagasta) kuehniella Zeller, and then reared in the lab-
oratory on eggs of P. saucia for four generations prior to this study at 21 + 2°C, 50 + 10% RH,
and under 14L:10D photoperiod.
Parasitized P. saucia eggs were isolated individually in gelatin capsules (20mm X 5 mm) to
obtain individual parasitoids for the following experiments. Only newly (< 3 h old) and singly
eclosed individuals (one parasitoid developed from each parasitized host) were used to prevent
any age and size factors of the parasitoids from influencing the results. Mated females were ob-
tained by placing two pairs of virgin females and males in a gelatin capsule (20 mm X 5 mm)
for 3-4 h. Because mating among virgin Trichogramma adults occurs readily (Nagarkatti and
Nagaraja 1978), it was expected that all females would be inseminated in such a situation. Both
mated and unmated females were unfed.
Fecundity and longevity.
Each of the mated and unmated females was transferred individually into a clear plastic Petri
dish (5O mm X 9 mm) containing 75 host eggs. Twenty-four hours following introduction, each
parasitoid was transferred into a second Petri dish containing 60 host eggs. The host eggs (= 60)
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 63
were then changed every second day until the 7. minutum died. Each female was a replicate and
each of two treatment groups (mated and unmated) contained initially 59 females (= replicates).
The experiments were conducted at 25 + 1°C and 60 + 10% RH with a 16L:8D photoperiod.
Following incubation for 7 days under the above conditions, the parasitized eggs were counted
using a dissecting microscope at 15X. To determine longevity, the parasitoids from the above
experiment were observed at 8 h intervals until they died. Fecundity of 7. minutum was evalu-
ated as the average number of parasitized host eggs per female, and longevity as the average
lifespan in hours.
Clutch size, emergence rate and sex ratio of F1 progeny.
A maximum of 20 parasitized host eggs per Petri dish were selected randomly and incubated
until adult parasitoids emerged. The numbers of male and female progeny and the uneclosed
parasitized eggs were counted. Uneclosed parasitized eggs were individually dissected to de-
termine the number of developing parasitoid offspring. Clutch size (the number of parasitoid
offspring produced per parasitized host) and emergence rate were calculated as:
total eclosed progeny + total uneclosed progeny
Clutch size = total parasitized host eggs incubated
total eclosed parasitized eggs
foal parasitized eggs incubated * !00%
Emergence rate =
Trichogramma minutum is an arrhenotokous species in which virgin females produce only
male offspring, whereas mated females produce both male and female progeny. Therefore, the
sex ratio of Fl progeny was only comparable among age groups of the mated females.
Data analyses. ee
The data were transformed as either arcsin /P or /x+0.5 before ANOVA (Zar 1984), where
P represents the percentage of emergence rate or sex ratio, and x is mean number of the para-
sitized eggs, clutch size, or longevity. One-way ANOVA was used to estimate significances.
Significant differences were separated by Duncan’s multiple range test at P = 0.05 level.
RESULTS AND DISCUSSION
Fecundity and longevity.
Mating status of female parasitoids significantly affected their daily fecundity (F = 15.34; df
= 1, 116; P=0.0002) (Table 1). Mated females parasitized more host eggs than unmated coun-
terparts on the first day of oviposition, but fewer on subsequent days. The results suggest that
mating stimulates female 7. minutum to deposit eggs quickly. The fecundity of T. minutum on
the first day of emergence in this study was greater than that reported by Yu et al. (1984) and
Smith and Hubbes (1986). Although mated and unmated T. minutum followed different prog-
eny allocation strategies in their lifetimes, their respective total fecundities per female were not
significantly different (F = 0.23; df = 1, 116; P = 0.6355). Yu et al. (1984) reported similar re-
Table 1
Effects of female age and mating status on fecundity of Trichogramma minutum.
Parasitized eggs per female + SE
Status Ist day 2nd & 3rd day 4th & Sth day Avg total
Mated 64.0+3.0 a' (59)’ 16.941.8 b (47) 3.7+0.9 b (3) 77.6£3.2 a (59)
Unmated 47.542.9b (59) 35.12: 2:4(95) 14.44+4.0 a (5) 81.4+4.0 a (59)
1. Values in the same column followed by the same letters are not significantly different at the 5% level of
Duncan’s multiple range test.
2. Numbers in parentheses represent replicates.
64 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
sults for T. minutum but Lund (1938) found that the total fecundity of unmated female T.
evanescens was significantly higher than that of mated females.
The total fecundity for 7. minutum in this study was lower than that reported by Yu et al.
(1984), 200 eggs, and Smith and Hubbes (1986), 128 eggs. However, Peterson (1930) found
that T. minutum deposited an average of 40.2 eggs in eggs of the oriental fruit moth, Grapholita
molesta (Busck). These differences in fecundity may be attributable to host differences (Smith
and Hubbes 1986). The relatively low fecundities reported here may also be due to lack of food
for the females. Yu et al. (1984) found that T. minutum fed with honey produced 236.8 eggs,
whereas unfed females deposited only 39.3 eggs.
The daily fecundity of T. minutum decreased significantly with age (mated: F = 96.16; df =
2, 106; P = 0.0001; unmated: F = 11.92; df = 2, 116; P = 0.0001), indicating that female Tri-
chogramma had most of their eggs ready for deposition at or shortly after emergence. Mated and
unmated females produced 82.4% and 58.3% of their total progeny on the first day. This pattern
is similar to previous observations (Yu et al. 1984; Smith and Hubbes 1986). The fact that 77i-
chogramma may lay a large proportion of their eggs on the first day of emergence should be
taken into account when timing inundative field releases of Trichogramma in biological control
programs.
Average longevity was different for mated and unmated T. minutum females, 53.6 + 2.1 (SE)
vs 59.6 + 2.1 h, (F=4.12; df= 1, 116; P=0.0446). Yu et al. (1984) observed similar results with
T. minutum reared on E. kuehniella, but Lund (1938) found no difference for T. evanescens.
Mating is known to reduce female lifespan in many insects (Partridge 1986) and may also do
so with T. minutum.
The longevity of 7. minutum observed in this study with unfed female parasitoids was much
shorter than that reported by Yu et al. (1984) or Smith and Hubbes (1986). Yu et al. (1984) found
that 7. minutum fed on honey lived for 612 h, whereas unfed females survived only 64 h. Star-
vation may be partly responsible for differences between measurement of female longevity
Table 2
Effects of female age and mating status on progeny emergence rate, clutch size and sex ratio of Tri-
chogramma minutum.
Emergence rate (%) + SE
Status Ist day 2nd & 3rd day 4th & 5th day
Mated 95. /aelolsa, (99) 96.0+1.4 a (47) 95,7£8.3 2G)
Unmated 96.6+0.8 a (59) 95.2+2.0 a (55) 98.4+1.6 a (5)
Clutch size
Mated X+SE 1.31+0.04 a (59) 1.25+0.04 a (47) 13320'33"arG),
Minimum 1 1 1
Maximum 5 4 4
Percentage of both sexes in the clutch size of two: 76.7+5.4
Unmated X+SE 1.32+0.04 a (59) 1.28+0.04 a (55) 1.25+0.30 a (5)
Minimum 1 1 1
Maximum 5 4 4
Male proportion (%) + SE
Mated? 20.1+2.1 b (59) 32.5+3.0 a (47) 46.1+12.2 a (3)
1. Values in the same column within each of emergence rates and clutch size followed by the same letters
are not significantly different at the 5% level of Duncan’s multiple range test.
2. Numbers in parentheses represent replicates.
3. Values in this row followed by the same letters are not significantly different at the 5% level of Duncan’s
multiple range test.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 65
here and those from previous studies. Differences in hosts may also have contributed to differ-
ent measurements of longevity, because host species appear to have significant effects on para-
sitoid lifespans (Smith and Hubbes 1986).
Clutch size, emergence rate and sex ratio of F1 progeny.
Mating status and age of female 7. minutum did not significantly (P > 0.05) affect emergence
rate (Table 2). The emergence rate of parasitized eggs was above 95% for both mated and un-
mated parasitoids, higher than the 82.5% reported by Smith and Hubbes (1986). Although off-
spring clutch size varied from 1.25 to 1.32 offspring per parasitized egg, no significant (P >
0.05) differences were found either between mated and unmated females or among maternal
ages (Table 2).
The overall sex ratio of T: minutum was female-biased and significantly affected by maternal
age (F = 8.31; df = 2, 106; P = 0.0004) (Table 2). Mated T: minutum produced a significantly
lower proportion of male offspring on the first day of oviposition than on subsequent days. A
similar increase in the proportion of male progeny with maternal age of T: minutum was reported
by Houseweart et al. (1983) and Smith and Hubbes (1986).
Adult sex ratio was estimated in this study. In this haplodiploid parasitoid, adult sex ratio
could reflect the initial sex ratio of the parasitoid eggs allocated to hosts at oviposition or dif-
ferential larval mortality between sexes or both. We found that a single P. saucia egg can sup-
port up to five 7. minutum, but this rarely occurs and average clutch size was only 1.3 offspring
per parasitized host (Table 2). Furthermore, it was observed that if two T. minutum developed
from a single cutworm egg, majority of them were one male and one female (see Table 2). Thus,
differential larval mortality of 7. minutum in this study is unlikely. Therefore, the observed adult
sex ratio is probably determined by the initial sex ratio of the wasp eggs. In arrhenotokous Hy-
menoptera, males develop from unfertilized eggs and females from fertilized eggs. An increase
in the proportion of males with maternal age may be due to depletion of sperm but further study
is needed.
ACKNOWLEDGEMENTS
We are most grateful to Dr. J.H. Myers (University of British Columbia, Vancouver, B. C.)
for allowing us to use her laboratory facilities for this study, and to Dr. M.B. Isman (University
of British Columbia) for providing the eggs of P. saucia. The authors thank Ciba Geigy Canada
Limited (Bio-Logicals) for providing the original 7. minutum for this study. This research was
funded in part by the National Research Council of Canada and the Science Council of British
Columbia.
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the egg parasitoid, Trichogramma pretiosum. Entomol. exp. appl. 64: 37-48.
Houseweart, M. W., D. T. Jennings, and S. G. Southard. 1983. Progeny production by Trichogramma minutum Riley
(Hymenoptera: Trichogrammatidae) utilizing eggs of Choristoneura fumiferana (Lepidoptera: Tortricidae) and
Sitotroga cerealella (Lepidoptera: Gelechiidae). Can. Entomol. 115: 1245-1252.
Jalali, S. K. and S. P. Singh. 1992. Differential response of four Trichogramma species to low temperatures for short
term storage. Entomophaga. 37: 159-165.
Lund, H. O. 1938. Studies on longevity and productivity in Trichogramma evanescens. J. Agri. Res. 56: 421-439.
Nagarkatti, S. and H. Nagaraja. 1978. Experimental comparison of laboratory reared vs. wild-type Trichogramma con-
fusum (Hym.: Trichogrammatidae) I. Fertility, fecundity and longevity. Entomophaga. 23: 129-136.
Navasero, R. and G. Elzen. 1992. Influence of maternal age and host deprivation on egg production and parasitization
by Microplitis croceipes (Hym.: Braconidae). Entomophaga. 37: 37-44.
Partridge, L. 1986. Sexual activity and life span. pp 45-54. In : Collatzs, K. G. and R. S. Sohal. (eds.), Insect aging strate-
gies and mechanisms. Springer-Verlag. Berlin.
Peterson, A. 1930. A biological study of Trichogramma minutum Riley as an egg parasite of the oriental fruit moth.
USDA Tech. Bull. 215.
Smith, S. M. and M. Hubbes. 1986. Isoenzyme patterns and biology of Trichogramma minutum as influenced by rear-
ing temperature and host. Entomol. exp. appl. 42: 249-258.
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Southard, S. G., M. W. Houseweart, D. T. Jennings, and W. A. Halteman. 1982. Size differences of laboratory reared
and wild populations of Trichogramma minutum (Hymenoptera: Trichogrammatidae). Can. Entomol. 114: 693-
698.
Stinner, R. E., R. L. Ridgway, and R. K. Morrison. 1974. Longevity, fecundity, and searching ability of Trichogramma
pretiosum reared by three methods. Environ. Entomol. 3: 558-560.
Yu, D.S. K., E. A. C. Hagley, and J. E. Laing. 1984. Biology of Trichogramma minutum Riley collected from apples
in southern Ontario. Environ. Entomol. 13: 1324-1329.
Zar, J. H. 1984. Biostatistical analysis. Prentice-Hall, Englewood Cliffs, N. J.
Assessment of sweepnet and suction sampling for evaluating
pest insect populations in hay alfalfa’
A. M. HARPER’, B. D. SCHABER, T. ENTZ, and T. P. STORY?
AGRICULTURE CANADA RESEARCH STATION, LETHBRIDGE, ALBERTA, CANADA, T1J 4B1
ABSTRACT
Insect populations in alfalfa grown for hay can be sampled using several methods. However, in
a pest management program a relatively easy, quick, and reliable method of sampling is essen-
tial for making effective pest control decisions. A study was conducted to determine if two dif-
ferent sampling methods, sweepnet sampling and suction sampling, led to similar pest control
decisions. Differences between sweepnet and D-Vac insect population estimates varied over
sampling dates and years and were dependent on the insect species, their developmental stages,
and abiotic factors. Our results indicate that, for many sampling dates, decisions on control of
some pest insects would be similar for the two sampling methods.
Insecta, Medicago sativa, alfalfa weevil, pea aphid
INTRODUCTION
Economically viable, environmentally responsible pest insect management depends on reg-
ular, accurate assessments of insect populations. The correlation between estimates from sam-
ples and absolute population estimates varies with crop growth factors (Bechinski and Pedigo
1982, Saugstad et al. 1967), the insects being sampled (Sedivy and Kocourek 1988), wind, and
air temperature (Saugstad et al. 1967). The sampling method used is also a source of error in es-
timating insect populations. The method chosen must be sufficiently accurate to identify popu-
lation fluctuations, but also simple and quick enough that it can be done frequently to allow
timely management decisions.
Comparisons of sampling methods have been inconclusive. In lentils, population estimates
of Lygus hesperus Knight from absolute, D-Vac, and sweepnet sampling were similar, but
nymphal numbers were lower with sweepnet sampling (Schotzko and O’ Keefe, 1986a). In soy-
beans, Bechinski and Pedigo (1982) found that for the predators, Nabis spp., Chrysopa spp. and
Coccinellidae, sweepnet sampling was superior, in terms of cost and variability, to plant shake,
absolute and vacuum sampling. Vacuum sampling was the least efficient method. However,
Shepard et al. (1974) found no significant differences among insect samples collected from
soybeans by
D-Vac, sweepnet, and plant shake. The Insectavac was reported to sample more insects per
unit area per volume of cotton sampled and, therefore, give a more accurate estimate of popu-
lation density than did the sweepnet (Ellington et al. 1984). Smith et al. (1976), however, re-
ported that both sweepnet and D-Vac sampling were adequate to identify population fluctua-
tions and indicate absolute populations in cotton. In alfalfa, Sedivy and Kocourek (1988) found
that D-Vac did not collect large, heavy insects such as caterpillars.
The objective of this study was to determine whether sweepnet and D-Vac sampling show
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 67
similar trends of pest insect populations in hay alfalfa and lead to similar decisions regarding in-
sect control in a variety of weather and crop conditions.
MATERIALS AND METHODS
At two sites in southern Alberta, insect populations in alfalfa (Medicago sativa L.) were sam-
pled weekly from May to October by a sweepnet and a D-Vac suction sampler (Dietrich 1961)
both before and after cutting for hay. The sites were located at the Agriculture Canada Research
Station at Lethbridge, Alberta. At Site 1, there were six plots, 10 x 20 m, of “Beaver” alfalfa,
and at Site 2, four plots, 10 x 15 m, of “Vernal” alfalfa. Both sites were sampled in 1978 and
1979. The two sites were about | km apart.
The insect samples consisted of five full-arm (180°) sweeps taken with a 38 cm diameter
sweepnet from half of each plot, and 10 suction samples (30.4 cm diameter) taken from the
other half of the plot with a D-Vac suction sampler (Model 1-A, D-Vac Company, Riverside,
CA). All sampling was conducted by the same person between 10:00 am and 12:00 am MST.
The samples were taken under dry conditions when the wind was less than 15 km/hour. In 1978,
the crop was cut for the first time on 26 June and again on 29 August. In 1979, the first cut was
on 5 July and the second on 7 September.
The pest insects identified and counted in the studies were: alfalfa weevil, Hypera postica
(Gyllenhal); pea aphid, Acyrthosiphon pisum (Harris); leathoppers, Cicadellidae; lygus, Lygus
spp., and alfalfa root curculio, Sitona scissifrons Say. With the exception of the alfalfa root cur-
culio, the pest insects were separated into mature and immature groups. The larvae of the alfalfa
root curculio are subterranean and, therefore, were not sampled.
With any sampling method, the actual number of insects obtained 1s directly dependent on the
volume of herbage sampled, regardless of the efficiency of the sampling method. Schotzko and
O’Keeffe (1989) determined that sampled herbage volume provided a better estimate of ab-
solute insect counts than considering only the area that was sampled. With sweepnet sampling,
the volume of herbage sampled is determined by the net diameter, the number of sweeps, the
length of each sweep, and the penetration of the crop canopy. The net size and the number of
sweeps can be kept constant, but the length of the sweeps and canopy penetration vary. There-
fore, the volume of herbage sampled is not fixed. Similarly for D-Vac sampling, the net size, the
number of samples, and the height of the canopy determine the volume of herbage sampled. The
height of the canopy varies, so the sampling volume is not constant for D-Vac sampling. Using
a conversion factor to obtain similar sampling volumes assumes a simple relationship between
insect densities and herbage volume, which may not be valid. As pointed out by Schotzko and
O’ Keeffe (1989), volume adjustments do not compensate for the location of the insects in the
canopy; they merely attempt to standardize the amount of canopy sampled. In our case, the
height of the canopy was different at each sampling date, so any attempt at standardizing the
sampled volume would have been unfeasible; therefore, we can provide only approximations
of the sampled volume.
The handle on the sweepnet was 0.90 m, the net opening had a 0.19-m radius, and five 180°
sweeps were taken. Therefore, from the volume equation for a torus, the theoretical sampled
volume is about 1.94-m’ (volume = pi’ X 0.19’ X (0.90 + 0.19) X 5). In practice, no more than
half of the sweepnet would usually penetrate the canopy, so the actual volume of herbage sam-
pled was less than 1.0 m’. The D-Vac had a net opening with a 0.152-m radius, and 10 samples
were taken each consisting of moving from the top of the canopy to the ground. Therefore, its
volume is V = pi X H X 0.152’ X 10, where H is the height of the canopy. From the forgoing,
the sweepnet and D-Vac appear to sample similar volumes when V = 1.0 m’, or when H = 1.38
m. Alfalfa is cut two to three times per year, generally before it reaches a height of 1.38 m; there-
fore, in our study the sweepnet probably sampled a larger volume of the canopy than the D-Vac.
Owing to the problems in sampling volumes as discussed above and because exact sampled
volumes were not obtained in this study, no statistical tests were made to compare directly the
differences in actual insect counts between the two sampling methods. Therefore, for our study,
the decision on control for an insect pest is based on the population trends obtained by the two
methods, not on specific economic thresholds. We followed procedures similar to those of Bra-
68 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
man and Yeargan (1990) to compare the two sampling methods. The means of the replicates and
their standard errors were calculated for each sampling date and plotted in order to display dis-
crepancies in insect counts between the sampling methods over the growing season. Each year’s
data were treated separately. Correlations between sweepnet and D-Vac insect counts were cal-
culated using estimates obtained from each replication throughout the sampling period. This
provided estimates of the trends over all sampling dates. Correlations were also calculated be-
tween insect counts obtained on a given sampling date and those obtained from the previous
sampling date (lag | correlations). In the absence of eradication measures, insect populations
generally should not change drastically within one week. Therefore, if the sampling methods
provide consistent estimates of insect populations, these lag 1 correlations should be high. All
calculations were made with SAS (SAS Institute Inc. 1985).
Table 1
Correlations (r) between sweepnet and D-Vac sampling estimates for five insects, two years, and two
locations
1978 1979
Site 1 Site 2 Site 1 Site 2
Insect (n= 56) (n= 83) (n= 56) (n = 84)
Aphid
Wingless 0.54** 0.81** 0.94** 0.86**
Winged 0.50** 0.54** 0.84** 0.87**
Lygus
Nymphs 0.20 OSl=+ O:92%* O62"
Adults Oa 0.06 0.48** 0.63**
Alfalfa weevil
Larvae 0.64** 0.54** 0.64** O79e%
Adults 0.15 0.36** 0.25 03557
Leafhoppers
Nymphs 0.38** 0.11 O78*= 0.14
Adults 0.54** 0.73** 0.55** 0.68**
Alfalfa root curculio 0.17 0.40** —0.02 0.54**
** Indicate significant correlations between the two sampling methods at p = 0.01.
Table 2
The lag | correlations (r) between observations from a given sampling date and those from the previous
sampling date for sweepnet and D-Vac sampling for five insects, two years, and two locations
1978 1979
Site 1 (n = 55) Site 2 (n = 82) Site 1 (= 55) Site 2 (n = 83)
Insect Sweep D-Vac Sweep D-Vac Swee D-Vac Sweep D-Vac
Aphids 0.80** 0.75**° O.80** 0.78** 0.844 ~- 0.844* “O85 e7 Ow Ors
Lygus O.40%* O54**" 0.79t* 0.65**") O:80* > (0.71**~ O807 sa O oom
Alfalfa weevil 0.72** 0.60** 0:80** “0.68** 0.40** ~O.81** "O71" Ome
Leaf hopper 0337 0315 0624 | 056%" . 2 O16 0.34* O153** “O67
Alfalfa root —0.05 0.16 0.52**_ 0.377" ». 0:03... 0:02 O.57** O47%%
curculio
** * Indicate significant correlations at p = 0.01 and p = 0.05, respectively.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 69
RESULTS AND DISCUSSION
Pea aphids
Correlations between sweepnet and D-Vac sampling ranged from 0.54 to 0.94 for the wing-
less and from 0.50 to 0.87 for the winged pea aphids (Table 1). Within a given year and loca-
tion, the correlations for the two aphid groups were quite similar. The lag | correlations ranged
from 0.75 to .90, indicating that the two sampling methods generally provided consistent esti-
mates of pea aphid populations over time (Table 2). In 1978, few large differences between sam-
pling methods were observed, the only exception being the fifth sampling date at Site 1 for
wingless aphids (Fig. 1). There the sweepnet sampling indicated almost 10 times as many wing-
less aphids as the D-Vac. In 1979, the D-Vac counts tended to be higher for winged and wing-
less aphids at peak population levels at both locations (Fig. 1).
Pea aphid counts in alfalfa are influenced by temperature, RH, cloud cover, the height of the
alfalfa, and wind speed (Saugstad ef al. 1967). For this insect, sweepnet sampling may not be
sufficiently precise to make absolute insect population comparisons, but may be useful for de-
termining population trends (Saugstad et al. 1967). Butin and Isenhour (1989) found that stem
and sweepnet counts were highly correlated for pea aphids in alfalfa. Our high correlations be-
tween sampling methods in 1978 and 1979 indicate a generally good agreement throughout the
sampling period (Table 1). Therefore, decisions on control of pea aphid populations would
probably have been similar for the two sampling methods (Fig. 1).
Lygus spp.
Correlations of lygus counts between sweepnet and D-Vac sampling ranged from 0.06 to
0.92, but the two sampling methods were inconsistent in detecting trends (Table 1). Lag 1 cor-
relations ranged from 0.40 to 0.83, indicating low agreement between successive sampling date
estimates at some locations (Table 2). The lag 1 correlations for the two sampling methods were
generally similar. In 1978, lygus nymphs at Site 2 and lygus adults at Site 1 showed few con-
sistent trends (Fig. 2). For 1979 at Site 1, the agreement between the two sampling methods was
consistent throughout most of the season. Neither sampling method consistently provided
higher lygus population estimates.
Schotzko and O’ Keeffe (1986a) found that lygus nymph counts with sweep-net sampling in
lentils were influenced by RH, temperature and light intensity, but adult lygus were not influ-
enced by any of the abiotic factors. These authors also found that the appropriate time for sam-
pling adult lygus bugs with the sweepnet did not coincide with that for sampling lygus nymphs.
In our study, the sweepnet and D-Vac sampling methods probably sampled different areas of the
alfalfa canopy; therefore, differences in counts between the two sampling methods for lygus
nymphs and adults, as well as the low lag 1 correlations, seem to indicate that both were influ-
enced by abiotic factors. Schotzko and O’Keeffe (1986b) concluded that sweepnet sampling
provided reliable estimates of adult lygus in lentils, but D- Vac sampling probably overestimated
both lygus adults and nymphs. Since the two sampling methods in our study provided almost
identical lygus counts on some sampling dates and significantly different counts on others (ly-
gus nymphs at Site 2 in 1978 and 1979), we can make no statement about the reliability of ei-
ther method for sampling lygus in alfalfa. The sweepnet probably sampled a larger volume of
alfalfa and often provided higher lygus counts; nevertheless, for some sampling dates the D- Vac
produced much higher counts than the sweepnet. This lack of consistency makes decisions
about the need to control lygus in alfalfa dependent in part on the sampling method and abiotic
factors at the time of sampling.
Alfalfa weevil
Correlations for adult alfalfa weevil ranged from 0.15 to 0.36, while correlations for larvae
ranged from 0.54 to 0.79 (Table 1). Within a given location and weevil growth stage, the corre-
lations for the two years were similar. In 1978, the lag 1 correlations for the two sampling meth-
ods were similar (Table 2). Lag 1 correlations ranged from 0.40 to 0.81, and were different for
the two sampling methods at site 1 in 1979. For 1978, the sweepnet sampling produced higher
larval counts for most of the sampling dates at both locations (Fig. 3). In 1979, both sampling
methods provided similar larval counts for most sampling dates. Adult alfalfa weevil counts
70 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
were low for both locations in both years (Fig. 3). Neither sampling method produced consis-
tently higher adult weevil counts, but for some sampling dates, the D-Vac produced substan-
tially higher counts than the sweepnet.
Cothran and Summers (1972) compared alfalfa weevil counts obtained from sweepnet and
square-foot, absolute sampling, and found that the sweepnet underestimated the actual popula-
tions, with the most severe underestimations occurred early in the developmental period of the
weevil larvae. They suggest replacing the sweepnet with another sampling method when accu-
rate estimates of alfalfa weevil are required. In our study, the alfalfa weevil larval population es-
timates obtained from sweepnet sampling in 1978 were substantially higher than D-Vac counts
for most of the sampling periods at both sites (Fig. 3). The higher counts obtained by the sweep-
Aphids - wingless
140 Site 1 ie Site 2
120
100
o8e8eee82 cxsee
Aphid counts per sample time
0 s
12345 6 7 8 9 1011 12 1314 12345 6 7 8 9 1011 12 1314
Sampling time
Figure 1. Influence of sampling method on counts of aphids.
\= Time of cut.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
Lygus nymphs
Site 1 1978 Site 2
\
Lygus adults
1978
Lygus counts per sampling time
1979
123 45 6 7 8 9 1011412 13 14 1234 5 6 7 89 10111213 14
Sampling time
Figure 2. Influence of sampling method on counts of lygus bugs.
A= Time of cut.
78!
72 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
Alfalfa weevil larvae
Site 1 1978 Site 2
1979
Alfalfa weevil adults
1978
Alfalfa weevil counts per sampling time
12345 6 7 8 9 1011 1213 14 12345 6 7 8 9 10111213 14
Sampling time
Figure 3. Influence of sampling method on counts of alfalfa weevils.
\= Time of cut.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 7
net could be due to a larger sampled volume, but if that is the case, why did the two sampling
methods produce very similar counts for some sampling dates? The D-Vac captured higher
numbers of adult alfalfa weevils than the sweepnet for some sampling dates, but there was no
consistency (Fig. 3). The early larval instars are located in the newly developing leaf and flower
buds and are not easily dislodged, whereas the late instar larvae and adults are found on the
leaves and are easily captured; therefore, the location of alfalfa weevil within the canopy may
have favoured one sampling method over the other on certain sampling dates. The low lag 1 cor-
relations for the sweepnet at site 1 in 1979 seem to support this suggestion.
Decisions about the need to control the alfalfa weevil would probably have been different for
the two sampling methods in 1978, but would not have differed in 1979. If sweepnet sampling
drastically underestimates alfalfa weevil larvae populations, as Cothran and Summers (1972)
found, then the underestimations from D-Vac sampling in our study seem to be even more se-
vere. However, the differences between D-Vac and sweepnet in alfalfa weevil population esti-
mates appear to be related to abiotic factors and weevil development.
Leafhoppers
Correlations between the two sampling methods for adult leafhoppers ranged from 0.54 to
0.73, and correlations for leafhopper nymphs ranged from 0.11 to 0.78 (Table 1). Lag 1 corre-
lations were generally low and ranged from 0.16 to 0.67, indicating that neither sampling
method provided consistent population estimates (Table 2). Nymphal leafhopper counts were
quite low for most sampling dates and few practically significant deviations were observed be-
tween the two sampling methods (Fig. 4). Some noticeable exceptions were very high counts
for the D-Vac on the third sampling date in 1978 at Site 1, and the first sampling date at Site 2
in both 1978 and 1979. D-Vac sampling produced higher adult leafhopper counts for most of the
sampling dates at both locations in 1979 (Fig. 4). Differences between sampling methods for
adult leafhoppers in 1978 were not as consistent as in 1979, but D-Vac sampling tended to have
higher counts.
Delong (1932) discussed some of the problems involved with sweepnet sampling and con-
cluded that, for active insects such as leafhoppers, sweepnet sampling is not very useful for ob-
taining accurate population estimates. Saugstad et al. (1967) obtained a high positive correla-
tion between leafhopper counts from sweepnet sampling and the height of the alfalfa, whereas
Cherry et al. (1977) found that wind and temperature were the two most important factors in
sweepnet estimates of adult leafhopper populations in alfalfa. These findings may explain some
of the variability between sampling methods and the low lag | correlations that we observed
over years, locations, and sampling dates. In 1979, adult leafhopper counts were higher in D-
Vac samples than in sweepnet samples for the whole sampling period. We can only speculate
that abiotic factors favoured D- Vac sampling because, theoretically, the volume of alfalfa sam-
pled by the sweepnet should have been higher than the volume sampled by the D-Vac. In 1979,
decisions to control leafhopper populations would have been different for the two sampling
methods.
Alfalfa root curculio
Correlations between sampling methods ranged from -0.02 to 0.54 (Table 1). The small neg-
ative correlation was the result of very low alfalfa root curculio counts at Site 1 in 1979 (Fig. 5).
The D-Vac samples had higher curculio counts than the sweepnet for the latter half of the sam-
pling period at both sites in 1978, and at Site 2 in 1979. The location of the curculio within the
alfalfa canopy was probably responsible for the higher counts obtained with D-Vac sampling,
even though the sweepnet may have sampled a larger volume. The very low lag | correlations
for both sampling methods indicate that neither sampling method provided consistent popula-
tion estimates (Table 2).
74 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
Leafhopper nymphs
Site 1 1978 Site 2
eo
$0
45
40
35
o
Es
in 20
2 15
@ 10
Ee 6s
wn 0
a
= Leafhopper adults
3 1978
8
o
a
(o%
°o
B x
ro
@
—
ons aSkRBRSE
ono andskSBbES
123 45 6 7 8 9 10111213 14 12345 6 7 8 9 10 111213 14
Sampling time
Figure 4. Influence of sampling method on counts of leafhoppers.
\= Time of cut.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 D
CONCLUSIONS
From our results, we conclude that, to obtain reasonable estimates of insect populations on
which to base insect control decisions with sweepnet or D-Vac sampling, the behaviour and
feeding patterns of the target insect need to be understood. Sampling conditions should optimize
the probability of capturing the target insect. This implies that sampling on fixed dates at fixed
times will probably influence the estimated insect populations since the abiotic factors will not
necessarily be optimal at the preselected sampling times. Furthermore, the optimal sampling
conditions vary among insect species and their developmental stages.
We also conclude that higher sampling volumes do not necessarily produce higher insect
counts, since the location of the insect in the alfalfa canopy and other factors are also important.
This makes the validity of post-sampling volume and area standardization questionable. After
alfalfa growth reaches 30 to 35 cm in height the sweepnet generally only samples the top por-
tion of the alfalfa canopy and, therefore, underestimates insects dwelling mainly in the lower
portion of the canopy. Sweepnet and D-Vac insect estimates are dependent on the insect species,
their stage of development, their location within the canopy, the crop being sampled, and abi-
otic factors. Therefore, when making pest control decisions, any sampling scheme that incor-
porates either of these two sampling methods must consider the above factors to obtain accu-
rate population estimates or trends.
Alfalfa root curculio
1978 .
14 Site 1 Site 2
—— Sweepnet
1979
Alfalfa root curculio counts per sampling time
Sampling time
Figure 5. Influence of sampling method on counts of alfalfa root curculio.
A= Time of cut.
716 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
NOTES
1. Contribution 3878943.
2. Retired.
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populations associated with cotton. Environ. Entomol. 5:435-444.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 oi |
The Aphids (Homoptera: Aphididae) of British Columbia
21. Further Additions
C.K. CHAN AND B.D. FRAZER
RESEARCH STATION, AGRICULTURE CANADA, VANCOUVER, BRITISH COLUMBIA, V6T 1X2
ABSTRACT
Seven species are added to the aphid fauna of British Columbia. Sixty-five of the 113 new
aphid-host associations of plant species are newly recorded.
INTRODUCTION
Four-hundred-and-five species of aphids collected from 1178 host plant species or in traps,
and 2321 aphid-host associations were recorded in previous lists of the aphids of British Co-
lumbia (Forbes and Chan 1989a, 1989b, 1991). The present list adds 7 aphid species (indicated
with an asterisk in the list) and 113 aphid-host plant associations to the previous lists. Sixty-five
of the new aphid-host associations of plant species are recorded for the first time. The additions
bring the number of known aphid species in British Columbia to 412. Aphids have now been
collected from 1243 different host plants and the total number of aphid-host associations is
2434.
The aphid names are in conformity with Eastop and Hille Ris Lambers (1976) and are listed
alphabetically by species. Names of native host plants are based on Anonymous (1982) and
Taylor and MacBryde (1977). Names of cultivated host plants are based on Anonymous (1976).
Thirteen new collection sites are given in Table 1. The reference points are the same as those
shown on the map which accompanies the basic list (Forbes et al. 1973). Most of the aphids
were collected by the authors.
LIST OF SPECIES
AEGOPODII (Scopoli 1763), CAVARIELLA
Apium graveolens ‘Prize Pink’ : Vancouver (UBC), Aug19/93.
Oenanthe sarmentosa: Amphitrite Point, Sep02/92.
AGATHONICA Hottes 1950, AMPHOROPHORA
Rubus idaeus ‘Algonquin’ : Abbotsford, Jul30/93.
Rubus idaeus ‘Chilliwack’ : Abbotsford, Jul30/93.
Rubus idaeus ‘Comox’ : Abbotsford, Jul30/93.
Rubus idaeus ‘Meeker’ : Abbotsford, Jul30/93.
AMERICANUM (Riley 1879), ERIOSOMA
Ulmus carpinifolia: Vancouver, May 18/93.
ANTIRRHINII (Macchiati 1883), MYZUS
Symphoricarpos x chenaultii: Vancouver (UBC), Jun16/93.
Vinca minor: Vancouver (UBC), Jun09/93.
* ARUNDICOLENS (Clarke 1903), TAKECALLIS
Arundinaria pygmaea: Vancouver (UBC), Sep16/92, Oct23/92, Nov25/92.
ASCALONICUS Doncaster 1946, MYZUS,
Arabidopsis thaliana: Vancouver (UBC), May06/83.
Corydalis aurea ssp. aurea: Vancouver (UBC), Mar22/85, May 11/83, Nov07/84,
Nov28/83.
Potentilla fruticosa ssp. floribunda: Vancouver (UBC), May20/93.
Spergularia rubra: Vancouver (UBC), Nov03/83.
AVENAE (Fabricius 1775), STTOBION
Agrotis exarata ssp. exarata var. exarata: Abbotsford, Jul21/93.
78 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
Bromus mollis: Abbotsford, Jul21/93.
Bromus pacificus: Abbotsford, Jul21/93.
Digitaria ischaemum: Cumberland, Sep03/92.
Digitaria sanguinalis: Abbotsford, Jul21/93.
Hordeum murinum: Abbotsford, Jul21/93.
Phalaris arundinacea: Abbotsford, Jul23/93.
Poa annua: Abbotsford, Jul21/93.
Zea mays ‘Miracle’ : Vancouver (UBC), Aug19/93.
AZALEAE (Mason 1925), ILLINOIA
Vaccinium corymbosum: Richmond, May22/93; Aug15/90.
BETAE Doane 1900, PEMPHIGUS
Lactuca sativa: Vancouver, Sep15/83.
*BETAE Westwood 1849, SMYNTHURODES
Phaseolus vulgaris var. humulis: Vancouver, Jul23/93.
*BLACKMANI Forbes & Chan 1993, SITOBION
Holodiscus discolor ssp. discolor: Vancouver (UBC), Mar19/84, Mar26/84, Apr14/86,
Apr16/86, Apr24/84, Apr30/86, May01/86, May08/84 Aug25/86, Sep20/84, Oct18/85,
Oct20/86, Oct2 1/86, Oct25/86, Nov02/83, Nov07/85, Nov08/85, Nov10/81 (Forbes &
Chan 1993).
BRASSICAE (Linnaeus 1758), BREVICORYNE
Capsella bursa-pastoris: Abbotsford, Jul15/91.
Table 1
Collection sites of aphids, with airline distances from reference points.
Distance
Locality Reference Point Dir km mi
Amphitrite Point Victoria NW 172 108
(Vancouver Island)
Chester Beach Victoria NW 193 121
(Vancouver Island)
Combers Beach Victoria NW 193 121
(Vancouver Island)
Cumberland Victoria NW 182 114
(Vancouver Island)
Forbidden Plateau Victoria NW 207 129
(Vancouver Island)
Gabriola Island Vancouver W 51 32
Green Lake Vancouver NE 103 64
(near Whistler) !
Grouse Mountain Vancouver N 12 8
Long Beach Vancouver W 210 130
(Vancouver Island)
Mount Washington Victoria NW 207 129
(Vancouver Island)
Radar Hill Vancouver W 210 130
(Vancouver Island)
Royston Victoria NW 179 112
(Vancouver Island)
Ucluelet Victoria NW has} 108
(Vancouver Island)
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
Brassica oleracea ‘Minaret’ : Vancouver (UBC), Aug19/93.
Brassica oleracea var. capitata ‘Red Rodan’ : Vancouver (UBC), Aug19/93.
Brassica oleracea var. capitata ‘Savoy King’ : Vancouver (UBC), Aug19/93.
CARAGANAE (Cholodkovsky 1907), ACYRTHOSIPHON
Caragana arborescens: Vancouver (UBC), Jun17/93.
Colutea arborescens: Vancouver (UBC), May18/93.
CARICIS (Glendenning 1926), SITOBION
Carex mertensii: Mount Washington, Sep04/92.
CARNOSUM (Buckton 1876), MICROLOPHIUM
Urtica dioica ssp. gracilis var. lyallii: Abbotsford, Jun04/93; Vancouver, Aug 18/89.
CERASI (Fabricius 1775), MYZUS
Prunus x yedoensis: Vancouver (UBC), May20/93.
CERTUS (Walker 1849), MYZUS
Spergularia rubra: Abbotsford, Jun21/92.
CIRCUMFLEXUM (Buckton 1876), AULACORTHUM,
Notholirion campanulatum: Vancouver (UBC), May20/93.
Potentilla fruticosa ssp. floribunda: Vancouver (UBC), May20/93.
CORNI (Fabricius 1775), ANOECIA
Agropyron repens: Abbotsford, Aug05/93, Oct13/92; Cumberland, Sep03/92.
CORYLI (Goeze 1778), MYZOCALLIS
Corylus cornuta var. californica: Abbotsford, Jun19/93.
CRACCIVORA Koch 1854, APHIS
Laburnum anagyroides: Vancouver (UBC), May20/93.
Laburnum x watereri: Vancouver (UBC), Jun25/93.
CRYSTLEAE (Smith & Knowlton 1939), ILLINOIA
Holodiscus discolor ssp. discolor: Vancouver (UBC), Jun15/93.
CYPERI (Walker 1848), THRIPSAPHIS
Carex mertensii: Mount Washington, Sep04/92.
DIRHODUM (Walker 1849), METOPOLOPHIUM
Echinochloa crusgalli: Westham Island, Aug12/93.
Phalaris arundinacea: Abbotsford, Jul23/93.
Rosa ‘Roseraie de L’ Hay’: Vancouver (UBC), Nov09/84.
DORSATUM Richards 1967, AULACORTHUM
Gaultheria shallon: Chester Beach, Sep03/92.
EQUISETI Holman 1961, SITOBION
Equisetum arvense: Vancouver, May29/93, Jun25/86.
EUPHORBIAE (Thomas 1878), MACROSIPHUM
Fagopyron esculentum: Abbotsford, Aug12/92.
Solanum nigrum: Abbotsford, Aug12/92.
Solanum sarrachoides: Abbotsford, Aug 12/92.
FABAE Scopoli 1763, APHIS
Euonymus hamiltoniana var. hans: Vancouver (UBC), Jun03/89.
Staphylea pinnata: Vancouver (UBC), Jul30/93.
FAGI (Linnaeus 1767), PHYLLAPHIS
Fagus sylvatica: Vancouver, May18/93.
FARINOSA Gmelin 1790, APHIS
Salix sp.: Vancouver, Jun14/87.
FIMBRIATA Richards 1959, FIMBRIAPHIS
Capsella bursa-pastoris: Abbotsford, May25/93.
Fragaria x ananassa ‘Totem’ : Abbotsford, Oct13/92.
80 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
FOENICULI (Passerini 1860), HYADAPHIS
Lonicera ciliosa: Gabriola Island, Jul10/93.
FRAGAEFOLII (Cockerell 1901), CHAETOSIPHON,
Fragaria x ananassa ‘Sakuma’ : Vancouver (UBC), Nov04/85.
Fragaria chiloensis: Long Beach, Sep03/92.
FRAGARIAE (Walker 1848), SITOBION
Fragaria x ananassa ‘Burlington’ : Vancouver (UBC), Nov04/85.
Fragaria x ananassa ‘Totem’ : Abbotsford, Sep29/92.
FRAXINIFOLII (Riley 1879), PROCIPHILUS
Fraxinus latifolia: Vancouver (UBC), May19/93.
Fraxinus oxycarpa: Vancouver, May 18/93.
Fraxinus pennsylvanica: Vancouver, May 18/93.
FREQUENS,(Walker 1848), DIURAPHIS,
Agropyron caninum: Abbotsford, Jul15/93, Aug05/93, Aug20/93.
Agropyronn repens: Abbotsford, Jul15/93, Aug05/93, Aug20/93.
Bromus pacificus: Abbotsford, Aug17/93, Aug20/93.
GENTNERI (Mason 1947), FIMBRIAPHIS
Crataegus mollis: Vancouver (UBC), May19/93.
Crataegus phaenopyrum: Vancouver, May 18/93.
GLYCERIAE (Kaltenbach 1843), SIPHA
Glyceria grandis: Vancouver, Sep15/89.
GOSS YPII Glover 1877, APHIS
Datura stramonium: Vancouver (CDA), Jun15/93.
HEDERAE Kaltenbach 1843, APHIS
Hedera helix: Combers Beach, Sep03/92.
HELICHRYSI (Kaltenbach 1843), BRACHYCAUDUS
Adelocaryum anchusoides: Vancouver (UBC), May31/89.
Crataegus mollis: Vancouver (UBC), May19/93.
Petasites palmatus: Vancouver, Jun22/87.
Symphytum officinale: Vancouver, Jun09/93.
HUMULI (Schrank 1801), PHORODON
Humulus lupulus ‘Nugget’ : Sardis, May 14/93, Jul22/93.
*INCOGNITA Hottes & Frison 1931, CEDOAPHIS
Symphoricarpos x chenaultii: Vancouver (UBC), May20/93; Jun16/93.
LACTUCAE (Linnaeus 1758), HY PEROMYZUS
Ribes sativum ‘Red Lake’ : Vancouver (UBC), Sep24/84.
LYTHRI (Schrank 1801), MYZUS
Prunus emarginata: Vancouver (UBC), May17/93.
MACROSIPHUM (Wilson 1912), ACYRTHOSIPHON
Amelanchier alnifolla: Green Lake, Nov05/92.
MANITOBENSE (Robinson 1965), SITOBION
Cornus alba ‘Sibirica’ : Squamish, Nov20/92.
NERVATA (Gillette 1908), WAHLGRENIELLA
Arbutus menziesii: Nanaimo, Oct13/92.
NICOTIANAE Blackman 1987, MYZUS
Solanum tuberosum ‘Russet Burbank’ : Abbotsford, Jul30/93.
NOXIA (Mordvilko ex Kurdjumov 1913), DIURAPHIS
Capsella bursa-pastoris: Vancouver (CDA), May15/93.
ORNATUS Laing 1932, MYZUS
Alyogyne hakeifolia: Vancouver (UBC), May20/93.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 81
Androsace geraniifolia: Vancouver (UBC), May20/93.
Arnica latifolia var. latifolia: Vancouver (UBC), Jun15/87.
Astartea fascicularis: Vancouver (UBC), May20/93.
Cuphea cyanea: Vancouver (UBC), Oct25/83.
Lithodora diffusa ‘Heavenly Blue’ : Vancouver (UBC), Jun21/85.
Phyllodoce empetriformis: Vancouver (UBC), May20/93.
Spergularia rubra: Vancouver (UBC), Nov03/83.
PADI (Linnaeus 1758), RHOPALOSIPHUM
Agropyron caninum: Abbotsford, Jul21/93.
Zea mays: Chilliwack, Aug29/83.
PARVIFOLII (Richards 1967), SITOBION
Vaccinium alaskaense: Forbidden Plateau, Sep03/92; Grouse Mountain, Jul24/93; Mount
Washington, Sep03/92.
Vaccinium ovalifolium: Grouse Mountain, Jul24/93.
PASTINACAE (Linnaeus 1758), CAVARIELLA
Heracleum sphondylium ssp. montanum: Ucluelet, Sep02/92.
PERSICAE (Sulzer 1776), MYZUS
Fagopyron esculentum: Abbotsford, Jun21/92.
Rorippa palustris ssp. palustris var. palustris: Abbotsford, Sep15/92.
Solanum nigrum: Abbotsford, Aug15/92.
Solanum sarrachoides: Abbotsford, Aug 15/92.
Solanum tuberosum ‘Norchip’ : Ladner, Jul27/93.
Solanum tuberosum ‘Russet Norkotah’ : Ladner, Jul27/93.
*PHLOXAE (Sampson 1939), OVATUS
Capsella bursa-pastoris: Abbotsford, May 15/92.
PISUM (Harris 1776), ACYRTHOSIPHON
Cytisus austriacus: Vancouver (UBC), May18/93, Oct04/84.
POAE (Gillette 1908), RHOPALOMYZUS
Phalaris arundinacea: Abbotsford, Jul23/93.
POPULIVENAE Fitch 1859, PEMPHIGUS
Rumex acetosella: Abbotsford, May11/93.
PRUNI (Geoffroy 1762), HYALOPTERUS
Phalaris arundinacea: Abbotsford, Jul23/93.
Prunus cerasifera ‘Bradshaw’ : Vancouver (UBC), Aug19/93.
PTERINIGRUM Richards 1972, AULACORTHUM
Vaccinium alaskaense: Grouse Mountain, Jul24/93.
ROSAE (Linnaeus 1758), MACROSIPHUM
Centranthus ruber ‘Albiflorus’ : Vancouver (UBC), Jun26/87.
Fragaria x ananassa ‘Burlington’ : Vancouver (UBC), Nov04/85.
Rosa multibracteata: Vancouver (UBC), Sep16/92.
Rosa soulieana: Vancouver (UBC), Sep16/92.
ROSARUM (Kaltenbach 1843), MYZAPHIS
Potentilla fruticosa: Cumberland, Sep03/92.
Rosa virginiana: Vancouver (UBC), Nov09/84.
RUMICIS Linnaeus 1758, APHIS
Rumex crispa: Abbotsford, Jun04/93.
SALICARIAE Koch 1855, APHIS
Cornus alba ‘Sibirica’ : Squamish, Nov20/92.
SOLANI (Kaltenbach 1843), AULACORTHUM
Adelocaryum anchusoides: Vancouver (UBC), May31/89.
Amelanchier laevis: Vancouver (UBC), May20/93.
82 J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
Arnica latifolia var. latifolia: Vancouver (UBC), Jun15/87.
Cardiocrinum giganteum: Vancouver (UBC), May16/93.
Eryngium varifolium: Vancouver (UBC), Jul13/87.
Hedera helix: Combers Beach, Sep02/92.
Hibiscus syriacus: Horseshoe Bay, Sep01/92.
Oxalis stricta: Vancouver (UBC), Jul13/87.
Rubus x loganobaccus: Vancouver (UBC), Oct16/92.
Symphytum officinale: Vancouver, Jun09/93.
SPYROTHECAE Passerini 1856, PEMPHIGUS
Populus nigra ‘Italica’ : Ladner, Jul30/93; Royston, Sep04/92; Westham Island, Aug20/93.
*STACHYOPHILA Hille Ris Lambers 1966, AMPHOROPHORA
Stachys cooleyae: Radar Hill, Sep03/92.
STAPH YLEAE (Koch 1854), RHOPALOSIPHONINUS
Buxus harlandi: Vancouver (UBC), Apr18/86.
Dianthus uralensis: Vancouver (UBC), Feb28/87.
Euonymus hamiltoniana var. hans: Vancouver (UBC), Jun03/89.
Staphylea pinnata: Vancouver (UBC), Jun03/89.
TENUICAUDA Bartholomew 1932, MACROSIPHUM
Urtica dioica ssp. gracilis var. lyallii: Abbotsford, Jun04/93; Vancouver, Aug 18/89.
TESTUDINACEUS (Fernie 1852), PERIPHYLLUS
Acer platanoides ‘Harlequin’ : Cumberland, Sep03/93.
Aesculus x carnea: Vancouver, May 18/93.
Aesculus hippocastanum ‘Rubricunda’ : Vancouver (UBC), May24/89.
TILTAE (Linnaeus 1758), EUCALLIPTERUS
Tilia platyphyllos: Vancouver, May 18/93.
Tilia tomentosa ‘Brabant’ : Vancouver (UBC), Oct16/92.
*TOLMIEA (Essig 1942), MACROSIPHUM
Tellima grandiflora: Vancouver (UBC), May29/93.
WAKIBAE (Hottes 1934), FIMBRIAPHIS
Vaccinium parvifolium: Vancouver (UBC), May18/93.
ACKNOWLEDGEMENTS
We wish to thank Dr. R.L. Blackman, British Museum (Natural History), London, England
for valuable aid and advice in identifying the aphids; and Dr. G.B. Straley, U.B.C. Botanical
Garden, Vancouver, B.C. for identifying host plants.
REFERENCES
Anonymous. 1982. National list of scientific plant names. Vol. 1. List of plant names. SCS-TP-159. U.S.D.A.
Anonymous. 1976. Hortus Third: A concise dictionary of plants cultivated in the United States and Canada. MacMil-
lan Publishing Co., Inc. N. Y. Collier MacMillan Publishers, Lond.
Eastop, V.F., and D. Hille Ris Lambers. 1976. Survey of the world’s aphids. Dr. W. Junk b.v., Publisher, The Hague.
Forbes, A.R., and C.K. Chan. 1993. Sitobion blackmani sp. nov. (Homoptera: Aphididae) from Holodiscus discolor ssp.
discolor (Rosaceae) in British Columbia. Can. Entomol. 125: 737-744.
Forbes, A.R., and C.K. Chan. 1991. The aphids (Homoptera: Aphididae) of British Columbia. 20. Further additions. J.
ent. Soc. Brit. Columbia 88: 7-14.
Forbes, A.R., and C.K. Chan. 1989a. Aphids of British Columbia. Res. Branch, Agric. Canada. Tech. Bull. 1989 - 1E.
Forbes, A.R., and C.K. Chan. 1989b. The aphids (Homoptera: Aphididae) of British Columbia. 19. Further additions.
J. ent. Soc. Brit. Columbia 86: 82-88.
Forbes, A.R., B.D. Frazer and H.R. MacCarthy. 1973. The aphids (Homoptera: Aphididae) of British Columbia. 1. A
basic taxonomic list. J. ent. Soc. Brit. Columbia 70: 43-57.
Taylor, R.L., and B. MacBryde. 1977. Vascular plants of British Columbia—A descriptive resource inventory. Tech.
Bull. No.4. The Botanical Garden. Univ. of B.C.
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993 83
First record of Pseudohaida rothi Hatch
(Coleoptera: Staphylinidae: Omaliinae) from Canada
J. M. CAMPBELL’ AND N. N. WINCHESTER?’
ABSTRACT
Pseudohaida rothi Hatch is reported for the first time from Canada from an old-growth, tem-
perate rain forest on Vancouver Island, B.C. Records of other rare species of the subfamily
Omaliinae are given together with a brief discussion of the importance of the remaining intact
old-growth forests in preserving the biodiversity contained in the forest regions of Canada.
DISCUSSION
Pseudohaida rothi was described by Hatch (1957), from two specimens collected by Vincent
Roth from the Corvallis, Oregon area. No additional specimens had been found when Pseudo-
haida and related genera were revised by Campbell (1978), and until recently, the species con-
tinued to be known only from the two original types.
One of us (Campbell) recently examined several large collections of staphylinid beetles made
by the second author (Winchester) in his systematic survey of the insects of a northern temper-
ate, coastal, old-growth rain forest in the Upper Carmanah Valley on the west coast of Vancou-
ver Island, British Columbia. These contained five specimens of Pseudohaida rothi, collected
by Malaise traps between the dates of September 30 to October 27, 1991. In addition to these
specimens, members of a number of other species of rare omaliine staphylinids were discov-
ered, including three specimens of Coryphium arizonense (Bernhauer), a long series of Sub-
haida ingrata Hatch, one specimen of Tanyrhinus singularis Mannerheim, three specimens of
Trigonodemus fasciatus Leech, and specimens of several new species of Omaliinae which will
be described in later papers.
Specimens of each of these species are preserved in the Canadian National Collection of In-
sects, Centre for Land and Biological Resources Research, Ottawa. It is hoped that these dis-
coveries will contribute to increased appreciation of the importance of intact old-growth forests
as reservoirs of biological diversity in the Pacific Rain Forests of Canada. Many species of
Coleoptera are restricted to old-growth forests where two important conditions for survival are
met: first, a supply of over mature, fallen logs which are allowed to decay under natural condi-
tions in the shade of the forest canopy and, secondly, the maintenance of deep layers of undis-
turbed forest floor litter which has not been eradicated by the extreme conditions of clear-cut-
ting and subsequent exposure to desiccation and erosion. Forest litter and decaying logs are rich
in a large variety of species of fungi, many of which also serve as hosts for species of beetles. It
should be noted that many of the species living in these mature forests have minimal dispersal
capabilities, thus limiting their ability to repopulate new forests.
ACKNOWLEDGEMENTS
Field work in the rainforest of the Carmanah Valley was supported by operating grants
to R.A. Ring and N.N. Winchester from the B.C. Ministry of Forests, Research Branch.
Acknowledgement is made to A. Mackinnon for his continued support. Special thanks are
extended to our research assistants, S. Hughes, K. Jordan and B. Lund.
NOTES
1. Centre for Land and Biological Resources Research, Agriculture Canada, Ottawa, Ontario, Canada, K1A 0C6
2. Dept. of Biology, University of Victoria, Victoria, British Columbia, Canada, V8W 2Y2
REFERENCES
Campbell, T.M. 1978. A revision of the North American Omaliinae (Coleoptera:Staphylinidae). Mem. ent. Soc.
Canada 106:87 pp.
Hatch, M.H. 1957. The Beetles of the Pacific Northwest. Part II. Staphyliniformia. Univ. Wash. Publ. Biol. 16:384 pp.
84
J. ENTOMOL. Soc. BRIT. COLUMBIA 90, DECEMBER, 1993
ERRATA
Volume 89, December 1992
Please note the following corrections to Volume 89 of the Journal of the Entomological Society
of British Columbia:
Blacker, N.C. 1992.
4
=)
Page's, line: 15.
» Page, 7;.line 36.
. Page 9, line 7.
Page 9. line 37:
. Page 12, line 15.
Some ants (Hymenoptera: Formicidae) from Southern Vancouver Island,
British Columbia. Entomol. Soc. Brit. Columbia 89:3-12.
Add “Table 1” before “Table 2”’.
“species” should read “‘specimens’’.
Add “‘but was never abundant. The colonies seen contained”’ before ‘“‘a
few hundred”’.
Add “‘twice”’ between “‘than”’ and “‘that’’.
Add “not” between “species” and “recorded”.
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Vernon, R.S. and D. Thomson. Effects of soil type and moisture on emergence of tuber flea
beetles, Epitrix Tuberis (Coleoptera: Chrysomelidae) from potato fields
Gray, T. and R. Shepherd. Hymenopterous parasites of the blackheaded budworm,
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Gray, T.G. and G. Gries. Sex pheromone components of an undescribed Choristoneura
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Li, S.Y. and D.E. Henderson. Response of Trichogramma sp. nr. sibericum
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Alfaro, R.I., M. Hulme and C. Ying. Variation in attack by Sitka spruce weevil,
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Clements, S.J., M.E. Bernard and D.A. Raworth. A versatile wind-resistant insect cage
Schaber, B.D., J.F. Dormaar and T. Entz. Effect of burning alfalfa stubble
for insect pest control on seed yield
Strong, W.B. and B.A. Croft. Phytoseiid mites associated with spider mites on hops
in the Willamette Valley, Oregon
Safranyik, L. and D.A. Linton. Relationships between catches in flight and emergence
traps of the mountain pine beetle, Dendroctonus ponderosae Hopk. (Col.: Scolytidae) .... 53
Li, S.Y., G. Sirois, D.L. Lee, C. Maurice and D.E. Henderson.
Effects of female mating status and age on fecudity, longevity and sex ratio in
Trichogramma minutum (Hymenoptera: Trichogrammatidae)
Harper, A.M., B.D. Schaber, T. Entz and T-P. Story. Assessment of sweepnet and
suction sampling for evaluating pest insect populations in hay alfalfa
Chan, C.K. and B.D. Frazer. The aphids (Homoptera: Aphididae) of British Columbia
NOTE
Campbell, J.M. and N.N. Winchester. First record of Pseudohaida rothi Hatch
(Coleoptera: Staphylinidae: Omaliinae) from Canada
Errata to Volume 89, December 1992
NOTICE TO CONTRIBUTORS
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