Four steinernematid strains, Steinernema carpocapsae All strain, S. carpocapsae Umeå strain, S. feltiae Lie strain, and S. feltiae strain 27, were evaluated in laboratory and field tests as potential agents for the control of the black army cutworm, Actebia fennica (Tauscher). Although each of the six instars was susceptible to attack, incidences of infection were highest and generally over 60% for the third, fourth, and fifth instars when exposed to 100 infective juvenile nematodes in petri dishes. Fifth-instar larvae exposed for 1 week to soil containing 4000 infective juveniles in a 1:1:1 mixture of the L1c, All, and Umeå strains were most frequently infected with the L1c strain when reared at 10 and 12 °C and with the All strain when reared at 14 and 16 °C. One hundred thousand infective juveniles of the L1c, All, and Umeå strains and strain 27, alone and in various combinations, and applied by either a spray or soil-plug inoculation, killed black army cutworm larvae caged in the field for 1 week with treated black spruce seedlings and provided protection of current and 1 -year-old foliage. Treatments that included strain 27 provided the best protection when daily mean soil temperatures were 7–11 °C in comparison to treatments that included the Umeå or All strains, whereas treatments that included the All strain as a component appeared to be more effective than treatments containing the L1c and Umeå strains when daily mean soil temperatures were 16–17 °C.

A commercial formulation of neem seed extract, Margosan-O, containing 0.3% AI azadirachtin, was tested under laboratory and field conditions against the European leafroller, Archips rosanus L. In laboratory tests, a 1% aqueous solution of neem insecticide produced 100% larval mortality within 48 h of treatment. At lower concentrations of 0.1 and 0.01%, 48-h mortality rates were reduced. Prolonged deleterious effects of sublethal treatments of neem were observed even at the lowest concentration (0.001%) tested. Mortality in the 0.1 and 0.01% treatments group reached 100% within 32–39 days after treatment. Field data showed that 3 weeks after application, 1% Margosan-O was as effective as the organophosphate insecticide diazinon and significantly more effective than the microbial insecticide Dipel (Bacillus thuringiensis). Larvae exposed to higher concentrations of neem died within 48 h after feeding on treated foliage. At lower rates, feeding deterrence (including cessation of feeding) and growth regulatory effects (e.g. difficulty in molting, abnormal larval growth, and formation of malformed pupae and adults) were recorded.

Arthropods associated with Populus coarse woody material (CWM) were sampled from aspen-mixedwood stands in north-central Alberta using rearings from wood bolts and flight-intercept traps attached to snags. More than 39 000 arthropod specimens were collected over 3 years, comprised mainly of Coleoptera, Diptera, Hymenoptera, and Acari. Detailed analyses are provided to compare the number of species, standardized abundance, and trophic structure between collecting methods for 257 saproxylic species of Coleoptera. Abundance of beetle species, from both rearings and window traps, and rarefaction estimates of species richness indicate little difference between methods with respect to expected number of species. However the abundance of particular beetle families differed significantly between methods, with the Aderidae, Anthicidae, and Scaphidiidae collected mainly in rearings and the Micropeplidae, Bostrichidae, Cephaloidae, Clambidae, Salpingidae, and Tenebrionidae more commonly collected with window traps. Fungivorous and predatory beetles were more abundant in CWM than wood borers, scavengers, or taxa with undetermined feeding habits, but the two methods revealed similar overall trophic structure. To census the variability in saproxylic arthropod faunas from CWM, a combination of collecting methods is recommended.

Emergence, oviposition, and seasonal flight activity of adult, speckled green fruit worm, Orthosia hibisci Guenée (Lepidoptera: Noctuidae), were monitored during 1991 and 1992 in a mixed block of McIntosh and Spartan apple trees at Summerland, British Columbia, to establish relationships between the phenology of these events and degree-days (DD). Using air temperatures and a developmental threshold of 3 °C, median emergence of males was predicted most accurately (0–2 days) by starting DD summations on 1 March. Median emergence of females was predicted without error when first catch of a male in a trap baited with sex attractant was used as a population reference point (biofix) to start DD summation. Using a threshold temperature of 3 °C, observed cumulative emergence of females reached 50% at 63.5 ± 4.05 DD3 °C after biofix, similar to the laboratory-derived prediction of 61.3 ± 4.2 DD with a threshold temperature of 2.8 °C. Catches of males with sex attractant preceded oviposition, but female catches in light traps lagged behind oviposition, suggesting older females were being caught in light traps. The oviposition curve was linear and parallel to the cumulative curve of male catches with sex attractant. Oviposition began at 26.7 DD3 °C and reached 50% at 94.2 DD3 °C after biofix, respectively. Weibull equations fitted to observed cumulative catches with sex attractant, female emergence, and oviposition, combined with laboratory-derived DD models of egg and larval development, were used to predict phenology of O. hibisci and correlate it with flowering phenology of pome fruits. This study provides a basis for timing application of selective insecticides against O. hibisci based on first catch in a sex-attractant trap and DD summations.

Photoperiodic responses are described for five clones of the potato aphid, Macrosiphum euphorbiae (Thomas) (Homoptera: Aphididae), from Manitoba, Canada, a region with a strongly seasonal, continental climate. When exposed to long nights, parthenogenetic wingless females produce winged males and parthenogenetic winged females that subsequently produce mating females. The young adult males and winged females are restless and take flight readily, which is typical of a post-teneral migratory phase that could carry them to a winter host. These traits are characteristic of host-alternating species. However, wingless females also produce mating females, and winged females also produce parthenogenetic wingless females, traits which are characteristic of nonhost-alternating species. Clones differ in the frequencies of phenotypes they produce, some being more host-alternating than others. Critical night lengths are shortest and frequencies of males highest for clones that are closest to the host-alternating type of life cycle. The importance of phenotypic and genotypic plasticity in the life cycle is discussed.

We designed a simple device for physically restraining live Diptera for measurement and marking. This new technique does not involve powders, anaesthetics, or handling with fingers or forceps, and can be adapted for use with flies of any size. We tested it on acalyptrate flies of 1.5–3.0 mm body length, and were able to sex, measure, and mark them with individual codes (enamel paint applied to the thoracic notum) in 5–7 min per fly, with a 96% success rate. This technique may be applicable to a range of behavioural and ecological research.

The dynamics of Aphis pomi De Geer (Homoptera: Aphididae) and its predator, Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae), were studied over two seasons in a commercial apple orchard in Nova Scotia. Aphid and predator population dynamics were very different in the two seasons. The most numerous predator in both years was A. aphidimyza. This predator was found in the earliest colonies sampled each season and was present throughout the growing season. In the year with relatively high aphid densities a single peak in aphid and predator density was seen in mid-July, just prior to maximum predation rate. The predator’s numerical response resulted in delayed density dependence in predation rate. In the year of low aphid densities, predator and prey dynamics appeared uncoupled, and a higher rate of colony turnover may have been caused by other predators such as mirids. Aphidoletes aphidimyza tended to aggregate oviposition in high-density aphid colonies, but this aggregation resulted in predation that was only very weakly spatially density dependent.

A chromatic mutation, dark body (mutants with a darker body than wild individuals), allowed us to test the effectiveness of the second mating in the bisexual species Trichogramma turkestanica Meyer, and of the first mating in the thelytokous species T. cordubensis Vargas and Cabello. Second mating in T. turkestanica was mostly efficient (i.e. followed by fertilization). Nevertheless, the latency before the second mating was longer as the time between second and first matings increased. The utilization of the spermatozoa from the second mating increased as the stock of spermatozoa from the first mating decreased. A long time in the presence of a male was necessary to obtain mating of the thelytokous females of T. cordubensis. Such fertilized females produced a low percentage (28%) of daughters from bisexual reproduction.

Adult potato aphids, Macrosiphum euphorbiae (Thomas), caged on potato terminal leaflets treated systemically with imidacloprid solutions ranging between 5.4 × 10−4 and 5.4 × 10−8 mL per mL water showed a significant reduction in the distance they travelled, time taken to travel a given distance, and flight propensity but no significant differences in the frequency or duration of short probing behaviour. The frequency of adult apterous potato aphids colonizing untreated potato leaflets or leaflets treated with an imidacloprid solution (5.4 × 10−4 mL per mL water) was not significantly different, indicating no repellency. Potato aphids moving from systemically treated to untreated leaflets did not recover much and their reduced walking ability was maintained for days. A 3-day exposure to vapour from an imidacloprid solution (5.4 × 10−4 mL per mL water) did not produce significant mortality or changes in nymphal production. The daily cumulative mortality obtained by caging potato aphids on potato leaflets placed in an imidacloprid solution (5.4 × 10−7 mL per mL water) was similar to that obtained in the field, on 20-day-old plants treated at planting with imidacloprid applied at 0.02 g Ai/m. None of the rates of imidacloprid tested stimulated the dispersal of apterous or alate potato aphids.

Laboratory studies of seven North American Choristoneura species and two subspecies from widely distributed locations demonstrate the low level of genetic separation among them. No differences were found in numbers (n = 30) or morphology of chromosomes among members of the group or in any of the hybrids examined. High levels of mating success were obtained in all inter se matings as well as in crosses and back-crosses. However, mating success was greater for crosses within host type and within pheromone type than for crosses between types. Viability and fertility were similar in all the hybrids and close to those of the inter se progenies. Mean weights of initial eggs varied by a factor of 2 from the lowest (C. pinus Freeman) to the highest (C. lambertiana ponderosana Obraztsov). Mean weights of initial eggs produced by hybrids were generally close to those of the parental species. However, when one parent was C. fumiferana (Clem.), mean weights of initial eggs were either much larger (male C. fumiferana) or much smaller (female C. fumiferana) than either parental type. These differences could affect survival of some progeny under harsh conditions. This evidence supports other studies in indicating that C. fumiferana is genetically distinct from other species in this group.

Among the 20 geometrid species recovered from annual surveys in coniferous forests in the Swiss Alps, three species, Epirrita autumnata (Borkhausen), Agriopis aurantiaria Hübner, and Poecilopsis isabellae Harrison, were identified as sources for parasitoids that might be suitable as candidates for introduction to Newfoundland to control the eastern hemlock looper, Lambdina fiscellaria fiscellaria (Guenée). Four univoltine Hymenoptera were identified as candidates: Dusona contumax (Forster) (Ichneumonidae) from A. aurantiaria, Dusona sp. from P. isabellae, Aleiodes cf. gastritor (Thunberg) (Braconidae) from E. autumnata, and Aleiodes. sp. from P. isabellae. The candidate parasitoids were confined with their native hosts in the laboratory and observations made to gather basic biological information and define protocols for screening.

Small numbers of these parasitoids were shipped to Newfoundland and screened in the laboratory against hemlock looper larvae. Although attacks by D. contumax, Dusona sp., and A. cf. gastritor were observed, parasitoid development did not occur. All parasitoid eggs recovered from the hemlock looper larvae attacked were encapsulated. Dusona contumax, Dusona sp. from P. isabellae, A. cf. gastritor, and Aleoides sp. from P. isabellae are not recommended for introduction against the eastern hemlock looper.

Several horticultural oils, an insecticidal soap, neem, garlic extract, a sugar ester, and a synthetic insect growth regulator were evaluated under laboratory conditions for their ability to inhibit pear psylla’s [Cacopsylla pyricola (Foerster)] feeding and oviposition. Supreme oil significantly reduced winterform oviposition rates in both choice and no-choice assays and reduced feeding rates in no-choice assays. Supreme oil also reduced oviposition rates of summerform females in choice tests but not in no-choice tests. In addition, summerform oviposition rates were reduced significantly by application of several mineral oils (Orchex 796E, 692, and WS2928) and garlic barrier to pear foliage in no-choice tests, and by all oils, garlic barrier, and M-Pede in choice tests. Summerform feeding rates were reduced by application of mineral oils. Data suggest that "summer type" oils and other compounds may have utility in pear psylla management programs by decreasing feeding and oviposition.

Species of the oribatid mite genus Tegeocranellus from North and Central America are discussed, and immatures are described for the first time. Six new species are described and keyed: Tegeocranellus alas from Costa Rica, T. barbarae from Alabama, Mississippi, and Florida, T. kethleyi from Alabama and Mississippi, T. mississippii from Louisiana and Texas, T. muscorum known from Ontario to Florida, and T. mediolamellatus from Guatemala. Descriptions of T. alas, T. barbarae, T. mediolamellatus, and T. muscorum are based on adults and immatures, and those of the other two species on adults only. I expand the generic diagnosis to include information on the apheredermous, plicate immatures, and present a character analysis hypothesizing that the monogeneric family Tegeocranellidae is a member of the Ameronothroidea, closely related to Selenoribatidae and Fortuyniidae.

Mayflies of the genus Ameletus (Ephemeroptera: Ameletidae) occur in practically every drainage of western Alberta and in the Cypress Hills, from headwater spring brooks to larger rivers. The genus is speciose and reaches its greatest diversity in the southwestern part of the province where as many as 12 species can occur at a single site. Of the 30 bisexual species currently recognized from North America, 13 have been collected from Alberta (A. bellulus, A. celer, A. cooki, A. majusculus, A. oregonensis, A. pritchardi, A. similior, A. sparsatus, A. subnotatus, A. suffusus, A. validus, A. velox, and A. vernalis), and another, A. inopinatus, is assumed to occur in the northern part of the province. Male adults of all North American species were described previously by Zloty (1996, The Canadian Entomologist128: 293–346). In the current paper, we describe late-instar larvae and adult females of all 14 Albertan species, and provide species distributions and keys for identification of male and female adults and larvae. All diagnostic taxonomic characters are described and illustrated. The identification keys can also be used in Saskatchewan, eastern British Columbia, Montana, and the northern parts of Idaho and Washington.

The potato aphid, Macrosiphum euphorbiae (Thomas) (Homoptera: Aphididae), is a host-alternating species and an important pest of Canadian flax. Populations of this aphid are highest in flax when the weather is warm and dry in July. Field-plot studies show that populations of the potato aphid increase rapidly in late July and early August and decline rapidly in mid-August. In some years potato aphids die because of a fungal epizootic or drought-induced senescence of the crop, but usually these factors do not account for the population decline. Field cage studies show that the potato aphid emigrates from the crop in mid-August. The photoperiodic response of the potato aphid and resulting emigration explain the population decline in flax, which occurs in mid-August each year regardless of the growth stage of the crop, population density, or average temperature at the time of the photoperiodic cue. Male and mating female potato aphids, born at the end of August, have time to develop, mate, and lay eggs before temperatures drop below the developmental threshold. The population decline assures that farmers need not sample or control the potato aphid in flax after mid-August.

The antibiosis of crucifers to flea beetles, Phyllotreta cruciferae (Goeze), was compared for Brassica juncea L., B. napus L., and B. rapa L. with low antixenosis, B. carinata L. and Sinapis alba L. with moderate antixenosis, and Thlaspi arvense L. with high antixenosis. Adult flea beetles collected from the field in early spring fed actively on intact or excised leaves of all plants except T. arvense. The beetles survived, and gained weight and fat on the Brassica species and S. alba, but not on intact foliage of T. arvense. No antibiosis was detected in any of the Brassica species or in S. alba. Intact foliage of T. arvense was so antixenotic that beetles probably starved rather than suffered from antibiosis. A low level of antibiosis was detected in excised foliage of T. arvense where the antixenosis was lost. These experiments show that estimates of beetle survival, dry weight, and fat content can be used in the laboratory to test small numbers of candidate plants for antibiosis. However, the level of antibiosis appears to vary less among Brassica species and related plants than does the level of antixenosis, and so the latter is a more promising type of resistance for use against flea beetles in canola.

Laboratory assays and field surveys showed that Ascosphaera larvis (Bissett) is a pathogen of alfalfa leafcutting bee larvae, capable of causing high mortality in commercial populations. In one population, over 21% of bees were found to be infected by A. larvis. However, overall levels of the disease are low and it is unlikely that this pathogen poses an immediate threat to commercial leafcutting bee populations in Canada. The LD50 was determined to be 1.9 × 105 spores/bee. Elevated levels of CO2 are required for in vitro spore germination. The disease can easily be diagnosed within bee cells by X-ray radiography, thereby enabling disease levels to be monitored using conventional methods utilized by the industry to monitor leafcutting bee quality.

Four surveys of Bombus workers found on various flower species generated classifications of bumble bees according to tongue length and corolla depth of flower species. The long-tongued bees frequented species with long corollas and short-tongued bees frequented species with short corollas. Within-species analyses revealed several significant positive correlations between tongue length and corolla depth. The advantage of short tongues in bumble bees was investigated in an analysis of working speeds of different species on white clover, which has a short corolla. Bees with short tongues were more efficient than bees with long tongues.

Synchrony of insect and host tree phenologies has often been suggested as an important factor influencing the susceptibility of white spruce, Picea glauca (Moench) Voss, and other hosts to the spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae). We evaluated this hypothesis by caging several cohorts of spruce budworm larvae on three white spruce populations at different phenological stages of the host trees, and then comparing budworm performance with host phenology and variation of 13 foliar traits. The beginning of the phenological window of susceptibility in white spruce occurs several weeks prior to budbreak, and the end of the window is sharply defined by the end of shoot growth. Performance was high for the earliest budworm cohorts that we tested. These larvae began feeding 3–4 weeks prior to budbreak and completed their larval development prior to the end of shoot elongation. Optimal synchrony occurred when emergence preceded budbreak by about 2 weeks. Larval survival was greater than 60% for individuals starting development 1–3 weeks prior to budbreak, but decreased to less than 10% for those starting development 2 or more weeks after budbreak and thus completing development after shoot elongation ceased. High performance by the budworm was most strongly correlated with high levels of foliar nitrogen, phosphorous, potassium, copper, sugars, and water and low levels of foliar calcium, phenolics, and toughness. These results suggest that advancing the usual phenological window of white spruce (i.e. advancing budbreak prior to larval emergence) or retarding budworm phenology can have a large negative effect on the spruce budworm’s population dynamics.

Female gypsy moth, Lymantria dispar (L.), exhibited a distinct calling rhythm at 17 °C, with peak calling ca. 4.0 h before the beginning of scotophase and minimal calling at or near the onset of the photophase (4.0 h). The rhythm persisted under continuous darkness (DD) and is thus circadian. The duration of calling in DD was shorter than that under a 16 h L: 8 h D photoperiodic regime. In contrast, under continuous light (LL) females called continuously and no overt rhythm was observed. Individuals kept under LL from the beginning of the pupal stage exhibited a distinct calling rhythm following a transfer to DD. The influence of temperature on the calling rhythm of L. dispar differed from most other species of moths studied to date. At lower temperature the onset of calling occurred later than at higher temperatures. The duration of the calling period increased from 11.1 h at 9 °C to continuous calling at 35 °C. The responses of females to temperature changes made at different times during the calling period suggest that the timing of calling in L. dispar does not depend on absolute temperature level.