The cylindrical bark beetle, Lasconotus intricatus Kraus., is attracted to multiple-funnel traps baited either with black spruce logs infested with male four-eyed spruce bark beetles, Polygraphus rufipennis (Kirby), or the male-produced aggregation pheromone, 3-methyl-3-buten-1-ol. The addition of the host terpenes, bornyl acetate and β-pinene, to 3-methyl-3-buten-1-ol reduced the attraction of L. intricatus. 3-Carene, myrcene, and α-pinene appeared to have a partial inhibitory effect. Catches in spring and summer disclosed a high degree of temporal coincidence between the two species. We hypothesize that L. intricatus utilizes the aggregation pheromone of P. rufipennis as a host-finding kairomone.

Male genitalia of Choristoneura species from the Nearctic Region and Palaearctic Region are described and illustrated. The study revealed that the male genitalia are among the most important body parts that contain valuable morphological characters for species distinction or grouping in this genus. They are potentially useful in the clarification of the taxonomic status of species in closely related species groups, such as the spruce budworm species complex in North America.

On the basis of 17 interpretable male genital characters and their corresponding evolutionary states, the phylogeny of the genus Choristoneura is inferred and proposed. Nine species groups are recognized: (1) fumiferana, pinus, biennis, orae, occidentalis, lambertiana, carnana, retiniana, and spaldingiana; (2) diversana, murinana, metasequoiacola, and jezoensis; (3) longicellana; (4) lafauryana; (5) conflictana and fractivittana; (6) hebenstreitella, adumbratana, and luticostana; (7) albaniana and lapponana; (8) rosaceana and parallela; and (9) obsoletana and zapulata.

Morphological evidence obtained in the present study suggests that two conifer-feeding species groups of Choristoneura, species group 1 from the Nearctic Region and species group 2 from the Palaearctic Region, are related. They represent the least evolved species groups in the genus. Choristoneura rosaceana, C. parallela, C. obsoletana, and C. zapulata, representing some of the species feeding on deciduous trees, are among the most evolved Choristoneura species.

The cabbage root maggot, Delia radicum (L.), was the only Delia species capable of attacking undamaged roots of canola [oilseed rape, Brassica napus (L.)] that was found in commercial fields in Manitoba. Adults of the overwintering generation infest canola. Their progeny, adults of the first generation, left the maturing plants after completing a single generation. Root maggot damage occurred in fields in all agricultural regions of the province. The mean percentage of the roots with damage was higher in the more northerly agricultural regions (15.8%) than in the south (8.0%). Most of the damage was light and the damage did not visibly affect the growth or vigour of the plants. Foot rot fungi were not associated with the feeding damage. In cage experiments, the seed yield of canola did not decrease with increasing proportions of plants damaged by D. radicum. The percentage of plants with root maggot damage (DAM) was best described in a polynomial by the mean daily air temperature (TEMP) and the total precipitation (RAIN) for June and July:

log(DAM + 1)=–12.3 + 0.66 TEMP + 0.09 RAIN – 0.004(TEMP × RAIN).

The level of damage caused by the larvae of D. radicum to canola in commercial fields during the years 1985 through 1988 did not appear to have caused yield losses. However, the level of damage increased with increasing precipitation and temperature during June and July so a series of favourable years could lead to increased damage and possibly to significant yield losses.

The persistence of toxic effects of the contact acaricides dicofol, propargite, and formetanate HCl and the ovicides clofentezine and hexythiazox to the European red mite, Panonychus ulmi (Koch), were tested by bioassays of disks cut from treated peach foliage. Effects of dicofol were more persistent than propargite or formetanate HCl to susceptible mites. Mortality on dicofol-treated foliage was >50% for more than 15 days. Propargite killed >50% of females for 10 days after application, whereas the toxicity of formetanate HCl deposits declined rapidly after 7 days. Mortality of dicofol-resistant mites was less than for susceptible mites. However, resistant mites were affected (>50% killed) by dicofol residues up to 7 days old. The toxic effects of the ovicides clofentezine and hexythiazox persisted for at least 30 days and at the rates tested were approximately equally toxic.

Formetanate HCl and propargite residues were less persistent (half-life 8–9 days) than the other compounds. Dicofol residues had a half-life of about 15 days but approximately 10% of residues persisted for 65 days. Residues of clofentezine and hexythiazox declined more gradually (half-life = 15–20 days) than other compounds and persisted at approximately 10% of initial residues after 65 days.

Psithyrus spp. (Hymenoptera: Apidae) are obligate social parasites of bumble bees (Bombus spp.). Morphological and physiological features of P. ashtoni (Cresson) females, which may facilitate the successful usurpation of host nests, were examined. Parasite females were no larger than B. terricola Kirby queens, although they possessed a number of protective modifications to the exoskeleton, as well as increased offensive armament, including larger mandibles and a longer venom gland. Females of P. ashtoni and P. insularis (Smith) possessed a greater number of ovarioles than host queens, and produced smaller eggs. The Dufour’s glands of the two Psithyrus species were significantly larger than those of B. terricola. There appears to have been considerable convergence in the evolution of socially parasitic lifestyles in bumble bees and wasps (Vespula spp.), presumably as a consequence of similar selective pressures operating on parasites belonging to these distantly related but socially similar taxa.

This study examines reproductive resource acquisition and utilization among Nicrophorus carrion beetles (Coleoptera: Silphidae) in two different and adjacent habitats. The proportion of small carrion resource (dead mice, Mus musculus L.) used by Nicrophorus and other scavengers in a Sphagnum bog did not differ significantly from that used in a nearby forest. Among congeneric Nicrophorus, N. vespilloides Herbst reproduced on small carrion exclusively in the Sphagnum bog, whereas a closely related species, N. defodiens Mannerheim, reproduced only in the nearby mixed forest. Nicrophorus sayi Laporte, N. orbicollis Say, and N. tomentosus Weber were rarely associated with small carrion resource in the bog, and reproduced primarily in the forest during the spring, summer, and fall, respectively. A significant positive correlation between brood size and weight of larval carrion resource was found for N. vespilloides.

The influence of nutrient stress on growth, development, and reproduction in apterous virginoparae of the pea aphid, Acyrthosiphon pisum (Harris), was investigated in the laboratory. We tested the hypothesis that species with a high reproductive investment have low resistance to starvation. Aphids in two groups were starved daily from birth for 4 h and 6 h, respectively, and compared with feeding counterparts reared on leaves of broad beans, Vicia faba L. Aphid wet weight increased as an exponential function of age in all groups. Starved aphids had lower adult weight and required longer from birth to parturition than feeding aphids. These effects increased with the length of daily starvation. The number of offspring produced was correlated with adult dry weight. Aphids were unable to compensate, or to compensate completely, for water and nutrient loss resulting from starvation. It is suggested that pea aphids allocate resources first to maintenance and then to reproduction when deprived of food.

Descriptions of Procloeon rubropictum (McD.), P. quaesitum (McD.), and P. rufostrigatum (McD.) are expanded to include features not previously published. A description of the nymph of P. quaesitum is given for the first time. Procloeon irrubrum sp.nov. is described from nymphs and female imagoes. From our interpretation of preliminary data, it is possible that P. rufostrigatum and P. rubropictum form one species group; P. quaesitum is included with P. pennulatum (Eaton) in another. Procloeon irrubrum does not fit either species group but shows some affinities to the P. rufostrigatum group. Some characters for separating the nymphs of Procloeon and Centroptilum are given.

The palearctic cutworm, Apamea ophiogramma (Esper), is reported from North America for the first time. Four specimens were collected at a light trap in Langley, British Columbia, in 1989, 19 in 1990, and 38 in 1991. Descriptions of wing markings and genitalic characters that distinguish A. ophiogramma from the nearctic Oligia fractilinea (Grt.) are provided.

European corn borer males have hair pencils located ventrally on the 8th sternite and these are extruded when a male approaches a calling female. The fact that (i) antennectomized females mated significantly less than both intact controls and individuals subjected to other forms of surgery, and (ii) males with hair pencils removed had a significantly lower mating success than control males, suggests that a male pheromone is involved in the mating system of the European corn borer.

The effectiveness of topical applications of the juvenile hormone analog Fenoxycarb against selected developmental stages of the eastern spruce budworm, Choristoneura fumiferana (Clemens), was determined. Eggs at an early stage of embryogenesis (0–24 h old) were prevented from hatching and were more sensitive to the compound than older eggs (48–72 h old) and larval stages. Fifth-instar larvae displayed lethal morphogenetic effects following Fenoxycarb treatment, but third-instar larvae were refractory. Adult females constituted the most sensitive stage; treated insects laid eggs that failed to hatch. Untreated adult females that mated with Fenoxycarb-treated males also laid infertile eggs.

Development and survival of the predatory pentatomids Podisus maculiventris (Say) and Podisus sagitta (Fab.) were studied at six constant temperatures ranging from 19 to 35 °C. Time required for development from egg to adult ranged from 48.9 days (19 °C) to 18.9 days (30 °C) for P. maculiventris and from 51.9 days (19 °C) to 16.9 days (33 °C) for P. sagitta. At 33 °C, eggs of P. maculiventris did not hatch and development of nymphs that had emerged at 23 °C was retarded; none of the first-instar nymphs incubated at 35 °C survived the next moult. A constant temperature of 35 °C was fatal to P. sagitta eggs and extended the developmental period of nymphs from 23 °C. Egg hatch ranged from 47% (19 °C) to 57% (27 °C) for P. maculiventris and from 54% (33 °C) to 71% (27 °C) for P. sagitta. Nymphal survival was high at moderate temperatures, with 63–78% and 65–82% of the first-instar nymphs of the respective species reaching adulthood. Mortality during the nymphal stage was significantly increased at high temperatures, but was considerably lower for P. sagitta than for P. maculiventris. Lower threshold temperatures for egg and nymphal development were estimated to be 10.7 and 11.7 °C for P. maculiventris, and 13.3 and 12.2 °C for P. sagitta. Thermal requirements for these stages were 78.2 and 275.5 degree-days, and 60.9 and 265.5 degree-days, respectively. These observations suggest that P. sagitta is somewhat better adapted to high temperatures than is P. maculiventris.

Importance of cultivars, harvest schedules, and pest infestations as determinants of alfalfa, Medicago sativa L., productivity and stand persistence was investigated using the unimproved “OK08” (Oklahoma Common) and the multiple-pest resistant “WL 318” cultivars. Beginning in the 5th year of production, treatments including three first-harvest schedules (early bud, early bloom, and full bloom) were imposed in a factorial arrangement with unsprayed subplots and three pesticide options for control of alfalfa weevil, Hypera postica (Gyllenhal), or weeds such as downy brome, Bromus tectorum L., or both. In addition to estimating population levels of alfalfa weevil and percentage composition of weeds in forage during each year, alfalfa dry matter yield and stem densities (no. per square metre) were determined during the 3-year period from 1986 through 1988. The seasonal forage production (2-year mean) of WL 318 was nearly 5.4 Mg per hectare greater than that of OK08. There was no consistent trend for greater seasonal alfalfa yield with any of the first-harvest schedules. Timely application of pesticides, as well as use of the improved cultivar were essential for maintaining productivity in years 5 through 7 of stand life. At the termination of the study, only the herbicide + insecticide treatment of WL 318 had close to sufficient stem (and plant) numbers remaining for continued production.

Stress caused by two biocontrol agents on their weed host Canada thistle [Cirsium arvense (L.) Scop., Asteraceae] was investigated. The combined attack of the gall-fly Urophora cardui (L.) (Diptera: Tephritidae) and the stem-mining weevil Ceutorhynchus litura (F.) (Coleoptera: Curculionidae) caused a significant reduction in the vigour of the attacked plants as measured by the number of live buds in the 1st year and by the dry weight of the roots in the 3rd year. The attacks did not significantly reduce the number of aborted buds, mature seed heads, and new shoots, nor the combined dry weight of the leaves, stems, and galls as compared with Canada thistle plants that had not been galled or mined, in any of the 3 years. Non-structural carbohydrate content of the roots of attacked shoots was found significantly reduced only at the end of the mining period.

Lygus species were sampled from the flowering heads and developing racemes of three species of Brassica [B. campestris L., B. juncea (L.) Coss., and B. napus L.] and two species of Sinapis (S. alba L. and S. arvensis L.) from cultivated fields during a survey from Prawda, Manitoba, to Lethbridge, Alberta. Lygus elisus Van Duzee and L. borealis (Kelton) were the most prevalent and abundant in Alberta and Saskatchewan; L. lineolaris (Palisot) was the most prevalent and abundant in Manitoba. Lygus rubrosignatus Knight, L. solidaginis (Kelton), and L. shulli Knight, previously unreported on Brassica, occurred in low numbers at most sites in Alberta and Saskatchewan.

Lodgepole pines, Pinus contorta var. latifolia Engelm., treated with the herbicide glyphosate applied by axe frill or drill hole into the sapwood around the root collar, were readily infested by mountain pine beetles, Dendroctonus ponderosae Hopk. On trees treated with 360 mg of glyphosate per centimetre of circumference, foraging woodpeckers, Picoides spp., debarked 15% of the bole surface within 10 weeks and > 30% after 1 year, compared with < 5% for controls. Foraging efficiency on mountain pine beetle at 4 m exceeded 90% after applications by axe frill of glyphosate at doses of 360, 36, and 3.6 mg per centimetre of circumference, compared with < 50% for controls. Glyphosate-treated trees rapidly became suitable for cavity excavation by woodpeckers.

Several insect species have life cycles that last more than 1 year, because of very slow growth, repeated or prolonged dormancies, or very long lived adults. These long life cycles are correlated with environmental adversities, such as cold or unpredictable temperatures, patchy, unreliable or low quality food supplies, and natural enemies, as well as with some other properties such as large size. Long life cycles are most prevalent when several of these factors are present simultaneously. Adversities tend to prolong the life cycle of all individuals in the population, whereas unpredictability tends to extend the life cycle of only some individuals. Extreme extensions, such as diapause for more than 10 years, usually affect only a very small fraction of the population. Modest extensions, such as development over 2 years, prolonged dormancy for one additional adverse season, cohort-splitting between 1- and 2-year life cycles, and oviposition over two seasons, are relatively common. Insects with long life cycles provide insights into the nature of adaptations to adverse and unpredictable conditions, and also provide useful material for the analysis of questions related to population and community structure.

Genetic divergence among populations of cone beetles, Conophthorus banksianae McPherson, C. coniperda (Schwarz), and C. resinosae Hopkins, was assessed by isozyme electrophoretic data. All but one of the eight loci examined were polymorphic, and one locus (Pgi) was sex-linked for C. coniperda. Genotype frequencies generally met Hardy-Weinberg expectations, and fixation index (FST) values indicated low-to-moderate genetic differences among conspecific populations. Fixed allele differences were detected at two loci, Pgi and Dia-2, which separated C. resinosae from C. coniperda, and thus confirmed their specific status established previously by morphological, karyological, and other biochemical characters. Electrophoretic data strongly suggested C. coniperda does not attack red pine cones, and C. resinosae does not attack white pine cones. No diagnostic loci were found to separate C. resinosae from C. banksianae. Phenetic clustering and pairwise comparisons of genetic distance coefficients indicated very little genetic divergence between C. resinosae and C. banksianae. These data were interpreted as failing to reject the null hypothesis that C. resinosae and C. banksianae are one species, an interpretation consistent with available taxonomic evidence from ecological, karyological, and other biochemical characters.

Records of anomalies in trichobothrial pattern in pseudoscorpions are rare. Different abnormalities in the location of trichobothria in Xenochelifer davidi Chamberlin (Chamberlin 1949), Roncus pripegala Ćurčić (Ćurčić 1988), Neobisium carpaticum Beier, N. cephalonicum (Daday) (Ćurčić 1980), N. simoni (L. Koch), and N. bernardi Vachon (Ćurčić and Dimitrijević 1989) have been reported. In the Neobisiidae, anomalies in trichobothrial disposition are confined to adults and tritonymphs. The aberrations include the following: the irregular distribution of some trichobothria on both pedipalpal chelae, although normal setal count is still maintained, as in N. cephalonicum (Ćurčić 1980); the reduction in the number of trichobothria due to reduction in size or some other anomaly of one or both pedipalpal chelae, as in N. bernardi, N. simoni, and N. carpaticum (Ćurčić 1980; Ćurčić and Dimitrijević 1989); or the occurrence of a supernumerary trichobothrium when both pedipalpal chelae are of normal length, as in R. pripegala (Ćurčić 1988).