An analysis of the primary setae and pores (campaniform sensilla) of first instars of 32 species of Colymbetinae, 61 species belonging to other dytiscid subfamilies, and seven species belonging to other families of Hydradephaga was performed to deduce the ancestral system of primary setae and pores of the head capsule and head appendages of Colymbetinae. Sixty-one setae and 46 pores have been assigned to the ground-plan pattern of the colymbetine larva, 27 setae and 20 pores on the head capsule and 34 setae and 26 pores on the cephalic appendages. The pattern proposed for the Colymbetinae is remarkably consistent and similar to the condition observed within the Carabidae. However, members of the Colymbetinae differ strongly from those of Hydroporinae which are characterized by several secondary losses. A preliminary phylogenetic reconstruction of the relationships of colymbetine genera studied based on 41 larval features suggests that the Nearctic fauna includes two monophyletic lineages: (1) (Agabus Leach + Ilybius Erichson) + Agabinus Crotch, and (2) {[Colymbetes Clairville + (Rhantus Dejean + Neoscutopterus Balfour-Browne)] + Matus Aubé}.

A set of six microprocessor-controlled mini-environmental chambers (0.04 m3 each) was designed, built, and tested. Chambers are capable of subfreezing temperatures (less than −10 °C) and can operate under constant or time-varying temperature regimes. Chambers are cooled by circulating ethyl alcohol from a reservoir chilled by an immersion cooler. Heat is provided by 17-W cartridge heaters. Temperatures are independently controlled by a single IBM 8088 computer instructing a data acquisition and control system. A single photoperiod is maintained by a commercial timer activating two miniature light bulbs in each chamber. Chamber temperatures were within 0.5 or 0.75 °C of the set temperature 65 or 94% of the time, respectively, during a 39-d test period. Minimum temperature capabilities were estimated for a variety of chamber configurations by an examination of the thermodynamic characteristics of the system.

Feeding on leaders of resistant Sitka spruce trees, Picea sitchensis (Bong.) Carr., Led to ovarian regression in white pine weevils, Pissodes strobi Peck., that contained already mature eggs at the time of caging on leaders. Such feeding also led to inhibition or a virtual blockage of ovarian development in weevils that did not contain already mature eggs at the time of caging. Ovarian maturation in such weevils was restored by application of juvenile hormone to female weevils. Effects of three levels of resistance were consistent within the experiments and with the field performance of the tested clones. These results indicate that the effects of resistance were postingestive, i.e., resistance was a form of antibiosis. How antibiosis can cause the weevils to concentrate oviposition on susceptible trees is discussed. Results also provide a means of selecting and ranking resistance of individual spruce trees for tree breeding and reforestation.

Plant bugs in the genus Lygus infest canola (Brassica napus L. and Brassica rapa L.) when the crop is producing buds, flowers, and pods. Field studies in cages and open plots show that plant bugs can reduce yield by 20% or more, but have little effect on seed size. A single application of a foliar insecticide when the crop has finished flowering and is beginning to produce pods will prevent most or all of the yield loss. The yield loss of canola that can be prevented by control is 0.007 t/ha per plant bug per 10 sweeps sampled at the end of flowering or the beginning of pod formation. The yield loss that can be prevented by a later application drops to 0.005 t/ha. When precipitation is greater than 100 mm from the onset of bud formation to the end of flowering, the crop may partially compensate for plant bug damage. The economic threshold for control of plant bugs in canola at the end of flowering or at the beginning of pod formation is 15 plant bugs per 10 sweeps, based on crop prices and control costs from 1989 to 1992. If plant bugs are present but control is not warranted when most flowering is complete, plant bug densities should be assessed again 5–7 days later as pods develop, but at this stage the threshold is 20 plant bugs per 10 sweeps. The use of economic thresholds for chemical control of plant bugs will maximize seed yield and minimize unnecessary or ineffectively timed insecticide applications.

Two new species of Isotogastrura, one from the Pacific coast and one from the Atlantic coast, are described: Isotogastrura ahuizotli sp.nov. and Isotogastrura veracruzana sp.nov. A key for the five species known at present is included.

One hundred and two Bacillus thuringiensis Berliner strains isolated from six different types of Canadian soil and dust from different grain storage bins were cultured in shake flasks containing Great Northern White Bean (GNWB) protein concentrate (48.6% protein) as the main nitrogen source and dextrose as the main carbohydrate source. The resulting endotoxins were bioassayed against the bertha armyworm, Mamestra configurata Wlk. Thirty-three percent of soil and 66% of grain dust samples were positive for B. thuringiensis. The bacterium was found most frequently in organic-rich soil. The four most toxic soil isolates (which were seven to 15 times more toxic than the international standard, HD1-S-1980), and two nontoxic grain dust isolates were characterized by serological typing, biochemical analysis, carbohydrate utilization, plasmid profile analysis, protein profile analysis using sodium dodecyl sulfate – polyacrylamide gels, and polymerase chain reaction. Four isolates were determined to be subsp. kurstaki containing 130–140 and 63–65 kDa proteins, and two isolates (tested for comparison) were subsp. canadensis containing 31 and 38 kDa proteins. Nonpyramidal-crystal-producing strains did not grow well in culture media containing GNWB, degossypellized cotton seed meal (61% protein), defatted soy flour (55% protein), or peptone as nitrogen sources. Excess of GNWB protein concentrate in shake flask culture media (30 g/L) inhibited bacterial growth and reduced the toxicity of isolate A1.2/72 subsp. kurstaki, which was the most toxic soil isolate. Isolate A1.2/72, which was 15 times more toxic for bertha armyworm larvae than the international standard (HD1-S-1980), contained three cry1A genes (cry1Aa, cry1Ab, and cry1Ac), whereas HD-1 lacked the cry1Ab gene. This strain was synergistic with strain HD-551 subsp. kenyae (cry1A, cry2A, and cry1B genes) but not with HD-133 subsp. aizawai (cry1Ab, cry1B, cry1C, and cry1D genes) when the strains were cultured together in a cotton seed meal medium and fed to M. configurata. The growth rate, economic yield, and toxicity of the new isolate, A1.2/72, produced in a 14-L laboratory fermenter declined when the fermentation ingredients were tripled. We believe that the indigenous strain A1.2/72 warrants further research development for bertha armyworm control.

The bertha armyworm, Mamestra configurata Walker, is a major pest of canola in western Canada. In 1994, 1995, and 1996 more than 670 000, 650 000, and 250 000 ha of canola were sprayed for bertha armyworm, respectively (Anonymous 1994, 1995, 1996). Despite the current trend towards increased acreage of canola production in western Canada, canola acreages declined markedly in 1996 from that planted in 1995 (Saskatchewan Agriculture and Food Statistical Facts 1996) in part because of the perception by farmers of the impact of bertha armyworm outbreaks in 1994 and 1995. Much research has been carried out in western Canada on the bertha armyworm with the aim of developing an integrated pest management program which includes the understanding of its biological control agents. Turnock (1984) reported that the native parasitoid complex of larval M. configurata consists of five species of Hymenoptera and 10 species of Diptera. Only two of these, namely Banchus flavescens Cresson (Hymenoptera: Ichneumonidae) and Athrycia cinerea (Coquillett) (Diptera: Tachinidae), have large negative impacts on its populations (Wylie and Bucher 1977).

The study of bee diversity and activity was conducted from January until June 1994 in a natural vegetation parcel (6200 m2) in Constantine (Algeria). The results showed the presence of 10 genera of wild bees visiting natural flowers and belonging to four families: Andrenidae, Anthophoridae, Halictidae, and Megachilidae. The Apidae family was represented by honeybee (Apis mellifera L.) and bumblebee (Bombus ruderatus siculus Dalla Torre et Friese). Census of bee populations revealed the abundance of wild bees with 66.26% of flowers visits, honeybee with 31.98%, B. ruderatus and Xylocopa violacea with 1.59 and 0.17% of total fauna, respectively. The beginning flight activity of these species started from a minimum threshold of temperature and humidity. The alimentary specialization was quantified by Simpson’s diversity index (Is) and by Shannon’s diversity index (Ish). Apis mellifera had the highest floral visits index (Is = 0.866) and the broadest alimentary niche index (Ish = 0.316).

Field tests were conducted in an argan forest in Morocco to evaluate the performance of a cylindrical dry trap and food-based synthetic attractant (FA) for monitoring the Mediterranean fruit fly (medfly), Ceratitis capitata (Weidemann). This female-targeted trapping system was compared with Jackson traps baited with trimedlure (TML), a male-targeted trapping system. TML-baited traps attracted significantly more males than FA-baited traps (91.4 ± 13.01 and 5.0 ± 0.75 males, respectively), and the FA-baited traps captured significantly more females than did TML-baited traps (9.3 ± 1.93 and 0.1 ± 0.04 females, respectively). For the first month of the field trial, the ratio of mature females to immature females captured in the FA-baited traps was approximately equal, but more immature females were captured in the second month. FA-baited traps were less specific and captured significantly more nontarget flies than did TML-baited traps.

We examined the effect of forest structure and climate on large-scale and long-term patterns of outbreaks of forest tent caterpillar, Malacosoma disstria Hbn., across central Ontario. This was done using previously published data on outbreak duration and forest heterogeneity, combined with high-resolution climatic data simulated by the recently developed Ontario Climate Model. Our analysis, which eliminates some of the spatially confounding effects of forest structure and climate, suggests that both the predicted long-term temperature minimum for the coldest month and the predicted growing degree-days in the first 6 weeks of the growing season are important determinants of outbreak duration, with colder weather being associated with shorter outbreaks. Forest heterogeneity accounts for more variation in outbreak duration than either of the climatic variables.

Reproductive processes in female Pissodes strobi (Peck) fed with a 5% ground bark artificial diet following summer emergence were studied. Females exposed to different temperature and photoperiod regimes were dissected every other week and their reproductive organs were observed to evaluate the maturation time according to the treatments. After 12 weeks, half the females were transferred onto lateral branch sections of white pine and the other half onto artificial diet supplemented with 10% ground bark of white pine, and their realized fecundity was determined. During the first 12 weeks, ovary development was detected but very few mature oocytes were found. No significant differences were observed for the maturation times between the different abiotic conditions used, but significant differences were observed in female egg-laying response on natural and artificial diets. Females that completed their sexual maturation at 24 °C and 16L: 8D laid over a 3-week period 14.4 ± 8.8 (mean ± SE) and 2.6 ± 2.6 eggs per female on white pine sections and artificial diet, respectively. Oviposition behaviour was compared with results from an earlier experiment conducted with spring-emerging white pine weevils on natural and artificial substrates. The egg-laying responses on white pine seedlings and on an artificial diet with a concentration of 15% ground white pine bark were 0.892 ± 0.124 and 0.171 ± 0.394 eggs per female per day, respectively.

Flight durations of male spruce budworm moths, Choristoneura fumiferana (Clem.), that were locked-on to pheromone plumes from female moths were measured in a wind tunnel. Flight was sustained by use of a movable patterned ceiling. The longest sustained flight was 53 min. The effects of different background concentrations of synthetic pheromone were tested by surrounding the female moths with rubber septa loaded with synthetic pheromone. The duration of sustained flights decreased as the concentration of background synthetic pheromone increased, but at all concentrations some males persisted in orientated flight for 10 min or longer.

The spruce budworm, Choristoneura fumiferana (Clem.), nuclear polyhedrosis virus (CfMNPV) has been studied extensively for its potential use as a bio-insecticide (Cunningham 1995). Recent advances in recombinant DNA technology have been impetuous in the genetic engineering of this virus to increase its virulence and (or) speed of action. This aspect of research has been concentrated on the modification of a plaque purified (Ireland strain) isolate obtained from the wild-type virus population (Arif et al. 1984). To assess any improvement in the effectiveness against the target pest, the virulence of the unaltered virus must first be determined. Bioassay results that have been previously reported by Kaupp and Ebling (1990) were conducted on the wild-type virus found in nature which consists of a mixture of viruses (Arif et al. 1994). Results of bioassays conducted to determine dose–response and time–response of fifth-instar spruce budworm larvae to the Ireland strain of CfMNPV are reported here.

Plant bugs in the genus Lygus are pests of canola (Brassica napus L. and Brassica rapa L.) in western Canada and may require insecticidal control. Sweep-net sampling of field plots and commercial fields in southern Manitoba between 1988 and 1995 was used to develop sequential sampling plans for plant bugs in canola to facilitate control. The variance–mean relationships for plant bug catches were defined by Taylor’s power law, and the parameters of the relationships were the same for field plots and commercial fields. Sampling units of 10, 20, 50, and 100 sweeps per sample had variance–mean relationships with the same slope but different intercepts and required different minimal sample sizes. Samples taken at two crop stages had similar variance–mean relationships, but at a later crop stage the intercept of the relationship differed and the parameters were estimated with less precision. Samples taken in two ways along the edges of commercial fields and at various distances into the fields all gave similar estimates of plant bug density, justifying the use of edge sampling. Experienced samplers caught more plant bugs than inexperienced ones, although the difference was primarily due to the number of nymphs rather than adults that were collected, and this difference was less pronounced in the edge samples. Sweep-net sampling collected less than 10% of the plant bugs present in the sampling area. Sequential decision plans are presented for four sampling units and three crop stages. Sampling commercial canola with a sweep net to make decisions on the need to control plant bugs can be completed in as little as 28–35 min. The sampling is most efficiently conducted with a sampling unit of 10 or 20 sweeps taken along the edge of a field. In an independent test of the sampling method, plant bug densities were classified correctly in relation to the need for control in 20 fields using the minimum sample size.

The genus Gynaephora Hübner (Lepidoptera: Lymantriidae) is represented in North America by two closely related species, Gynaephora groenlandica (Wocke) and Gynaephora rossii (Curtis), whose geographic distributions overlap broadly across the Canadian arctic archipelago (Ferguson 1978; Møllgaard and Morewood 1996). Like other lymantriid moths, females of these species fly little, if at all, whereas males are strong fliers and apparently rely on pheromones to locate mates. Cross-attraction has been observed but there is no confirmed evidence that the two species interbreed. This report describes experiments designed to document reproductive isolation of G. groenlandica and G. rossii at Alexandra Fiord, Ellesmere Island (78°53′N, 75°55′W).

Preserved Coleopteran remains dating to the last quarter of the 17th century were recovered from historical latrine or privy contents in Boston, Massachusetts. This analysis yielded 15 individuals of the striped flea beetle, Phyllotreta striolata (Fabricius). Its presence represents the earliest known record of this species in North America and demonstrates that it was introduced at least a century earlier than previously thought. The species history and possible modes of introduction are discussed.

We assessed the robustness of a standard classification of foliage suitability of North American tree species to the gypsy moth (Lymantria dispar L.) for tree species of southern Quebec grown under contrasting water regimes. Dispersal trials for 1st-instar larvae and feeding trials for 4th-instar larvae were conducted to determine whether water regime and (or) maternal effects influenced the preference or avoidance of gypsy moth larvae for foliage from saplings of native tree species of Quebec. We found no effect of water regime on the suitability of foliage to 1st-instar larvae and no effect of water regime and maternal effects for 4th-instar larvae. The standard classification scheme used by U.S. Department of Agriculture researchers in the United States was generally robust to the above factors, and thus suitable for use in southern Quebec.

Diplolepis rosaefolii (Cockerell) induces a lenticular gall on the leaves of various roses across Canada. In Ontario and Quebec, D. rosaefolii is found only on Rosa acicularis Lindl., and its galls are inhabited by eight species of parasitoids, the most common being Chrysocharis pentheus (Walker), Orthopelma luteolator (Gravenhorst), and Eupelmus dryorhizoxeni Ashmead. Parasitoids and the inquiline Periclistus sp. make up 48–62% of gall inhabitants. Here we report a population of D. rosaefolii on the hybrid rugosa shrub rose Thérèse Bugnet in a field of experimental roses in Quebec. Only two species of parasitoids and one specimen of Periclistus sp. were associated with these galls.

We carried out a 2-year study to elucidate the biology of the gregarious, idiobiont ectoparasitoid Elachertus cacoeciae (Howard) by placing (implanting) laboratory-reared spruce budworm larvae [Choristoneura fumiferana (Clemens)] on current-year balsam fir (Abies balsamea L.) shoots in the field, simulating low (endemic) densities of the budworm. Spring female E. cacoeciae attacked fourth-, fifth-, and sixth-instar budworm larvae, beginning near the predicted peak of the fourth instar and ending about 10–12 days after the predicted peak of the pupal stage of the wild budworm population. The mean (±SE) brood size of spring females was 2.9 ± 0.3 E. cacoeciae pupae per host. The proportion of females increased during the season, with many broods consisting of 100% females late in the season. In 1994 and 1995, the mean proportion of females was 0.74 ± 0.05 and 0.79 ± 0.05, respectively. In the laboratory, development time from eggs to adults was approximately 20 days at 20.6 °C. Adult males provided with honey water lived 43.6 ± 3.2 days, whereas females provided with hosts and honey water lived 90.1 ± 6.6 days. Spring females had a pre-oviposition period of 11.5 ± 1.3 days, resulting in a generation time (egg to egg) of ~31 days. The oviposition period lasted 76.3 ± 7.7 days during which time spring females parasitized 19.2 ± 1.9 hosts, and produced a clutch size of 4.9 ± 0.4 eggs per host, for a lifetime fecundity of 96.8 ± 14.7 eggs. The post-oviposition period was 18.5 ± 3.7 days. Throughout their lifetime, spring females host fed only (host feeding without oviposition) on an additional 9.3 ± 1.9 hosts. Approximately 2% of pupae developing from spring females overwintered, whereas approximately 95% of pupae developing from summer females overwintered. Laboratory results for summer females suggest that they may be adapted to parasitizing alternate host(s) rather than spruce budworm.

The apple leaf midge, Dasineura mali (Kieffer), is an apple pest in Nova Scotia's Annapolis Valley (Rogers 1991). Larval D. mali are specialist, leaf-feeding pests that attack primarily young pubescent apple shoots. Larval feeding induces the leaves to curl tightly toward the midrib and form distinctive reddish galls that desiccate following larval exit. Economic damage to orchards in Annapolis Valley has not been estimated, but immature trees and nursery stock are vulnerable because new growth is essential for proper tree formation (Rogers 1991).