We present the results of electrophoretic analyses of allozymes for eight population samples of the arctic/alpine sweat bee, Lasioglossum (Evylaeus) boreale Svensson, Sakagami and Ebmer. This holarctic species is found at high latitudes and at increasingly high elevations in the mountains of western North America as far south as southern Arizona. Our samples encompass a large proportion of the species' range; three samples are from Arizona, one from Utah, two from northern Canada, one from Mount Washington (the highest point in the eastern United States), and one from Sweden. Most samples had high levels of genetic variation compared with other bees, but the one from Sweden had low heterozygosity, suggesting that this location may have been comparatively recently colonized. The three northern North American samples were genetically similar despite the large geographic distances separating the localities (average > 3000 km). In contrast, the southern United States samples were (with the exception of one pairwise estimate) genetically divergent despite the small geographic distances separating them (average < 500 km). These results are consistent with earlier divergence among the southern populations, which are currently separated by regions of low elevation and inhospitable desert, than among the more northern ones. Although the data are not conclusive, they are suggestive of northward dispersal from refugia south of the ice sheets since the last glaciation.

Descriptions of the larvae of Lancetes angusticollis (Curtis), L. lanceolatus (Clark), L. subseriatus Zimmermann, L. flavoscutatus Enderlein, L. delkeskampi Ríha, and L. nigriceps (Erichson) are provided. Characters from larval morphology are analyzed to infer the phylogenetic relationships of the genus Lancetes Sharp with other genera of Dytiscidae. A parsimony analysis based on 51 informative larval characteristics was conducted with the program NONA. The most parsimonious tree supports a sister-group relationship between the genus Lancetes and members of the subfamily Dytiscinae. The only unambiguous synapomorphy in support of this hypothesis is the secondary subdivision of some cephalic appendages. Other putative synapomorphies are the proximal articulation of the primary seta CO7 both on meso- and meta-coxa and the presence of additional primary setae on the ventral margin of the tibiae. Based on several character states including the presence of multifragmented urogomphi, the genus Lancetes is monophyletic.

The effectiveness of felt egg traps to detect oviposition by the cabbage maggot, Delia radicum (L.), was studied under field conditions for cabbage, Brassica oleracea L. var. capitata L. (Brassicaceae), and rutabaga, Brassica napus L. var. napobrassica (L.) Reichenb. (Brassicaceae), in 1994 and 1995. The numbers of eggs laid on traps were compared with the numbers deposited in the soil next to the plant. Also, the incidence of oviposition (i.e., the percentage of samples with eggs) on soil and traps was compared. A total of 5160 eggs was collected from 5208 samples, but just 16% of all samples had eggs. For cabbage, early in the 1994 season, the incidence of oviposition in soil samples was double that on traps, and the number of eggs per sample was greater also. Oviposition incidence and the number of eggs per sample during the rest of the summer were similar. In the 1995 cabbage trial, the incidence of oviposition early in the season was again higher in soil samples than on traps, and there were fewer eggs per trap than per soil sample. For rutabaga, the number of eggs was similar using both methods early in the second generation, but from mid-August there were more eggs per trap than per soil sample. The incidence of oviposition in the rutabaga trial was similar on traps and in soil through most of the experiment. In this study, felt traps did not adequately detect the timing of cabbage maggot oviposition in the critical early season.

Female spruce seed moths, Cydia strobilella (L.) (Lepidoptera: Tortricidae), oviposit on seed cones of most North American spruces (Picea spp.) (Pinaceae) at the time of pollination, and larvae feed on seeds in the maturing cones. We tested the hypothesis that host-seeking moths respond to volatiles from both host and nonhost trees. In coupled gas chromatographic – electroantennographic detection (GC–EAD) analyses of extracts of spruce seed cone volatiles, > 17 compounds elicited antennal responses from male and female C. strobilella. A blend of seven compounds, including (−)-α-pinene and (−)-β-pinene, α-longipinene and α-humulene, Z3-hexenol, methyl eugenol, and cymen-8-ol, was more attractive to female C. strobilella in laboratory bioassay experiments than the complete seed cone volatile blend, containing these compounds at equivalent quantities and ratios. In GC–EAD analyses of volatile extracts from nonhost angiosperm trees, EAD-activity was associated with compounds present in (almost) every volatile source, including trembling aspen, Populus tremuloides (Michx.) (Salicaceae), paper birch, Betula papyrifera (Marsh.) (Betulaceae), black Cottonwood, Populus balsamifera trichocarpa (Torr. and Gray) (Salicaceae), and bigleaf maple, Acer macrophyllum (Pursh.) (Aceraceae). In a field experiment in the interior of British Columbia, the antennally active nonhost aldehydes, alcohols, and (±)-conophthorin all reduced captures of male C. strobilella in pheromone-baited traps. Collectively, our data suggest that host selection by C. strobilella is mediated, in part, by semiochemicals from both host and nonhost trees.

The cranberry girdler, Chrysoteuchia topiaria (Zeller) (Lepidoptera: Pyralidae), is the most important sod webworm species attacking turfgrasses in Quebec, Canada (Simard 2001). Unlike other webworms, the cranberry girdler is rarely observed on grass blades but feeds on the crowns and roots in the thatch. Biopesticides based on a nematode–bacterium complex appear to hold promise as a means of controlling turfgrass insect pests, particularly those that colonize the thatch and the first few centimetres of soil (Potter 1998), such as the cranberry girdler (Georgis and Hague 1991). Our objective was to assess the susceptibility of the cranberry girdler to entomopathogenic nematodes. In the laboratory, we determined the LC50 values for four nematode species and evaluated the effect of contact time on host mortality.

Codonopsimyzus sasammi, gen.nov., sp.nov., and Aulacorthum ligularicola, sp.nov., are described from specimens collected in South Korea on Codonopsis lanceolata Trautv. (Campanulaceae) and Ligularia fischeri Tucz. (Asteraceae), respectively. Both species are illustrated with the biométrie data for apterous viviparous females and alate viviparous females. The host plants and a brief description of the biology are also provided for each species. A revised key to the species of the genus Aulacorthum Mordvilko in Korea and a key to Korean genera of macrosiphine aphids related to Codonopsimyzus, sp.nov., are presented.

The meiotic formula of the European spruce beetle, Dendroctonus micans (Kugelann), is 10 AA + Xyp in males and 10 AA + XX in females. This karyotype is different from the morphologically similar Dendroctonus punctatus LeConte (14 AA + Xyp), which is consistent with the taxonomic validity of both species. The chromosome number found in D. micans, added to karyological data from other species of the genus Dendroctonus Erichson, suggest that the karyological diversification within this genus may have occurred in two directions: one toward more southerly latitudes in North America and the other toward Europe and Asia.

Larvae of the predatory gall midge Feltiella acarisuga (Vallot) diapaused as prepupae in tightly woven, brown, silk cells on leaf surfaces. Photoperiod alone, at day lengths from 16 to 8 h did not induce diapause at either 20 or 25 °C. A low incidence of diapause was induced by a combined photoperiod and thermoperiod of an 8-h day at 25 °C and a 16-h night at 15 °C. The incidence of diapause was higher under these conditions if the larvae were fed diapausing spider mites, Tetranychus urticae (Koch) (Acari: Tetranychidae). Because F. acarisuga only diapauses at daylengths equivalent to mid-winter, when its prey, T. urticae, is also in diapause, it can be used as a biological control agent for T. urticae in British Columbia greenhouses throughout most of the growing season.

Escape from natural enemies may favor the incorporation of a novel host plant into the diet of an herbivorous insect. This scenario has been suggested for the recent host-plant shift by the goldenrod stem galler, Eurosta solidaginis Fitch (Diptera: Tephritidae), from the ancestral host Solidago altissima L. (Compositae) to the derived host Solidago gigantea Ait. In this study, we examined the effects of predation from downy woodpeckers, Picoides pubescens L. (Aves: Picidae), and black-capped chickadees, Parus atricapillus L. (Aves: Paridae), on these two host races of insects at the western edge of their zone of sympatry. Based on a field census, bird predation was concentrated near the cover of trees where S. gigantea tends to occur; few attacks occurred in the open where S. altissima is prevalent. We conducted a field experiment to evaluate the preference of these avian predators for galls of the two host races when differences in the microgeographic distribution, size, and height of galls were controlled. In allopatric sites where only S. gigantea occurs, attacks by birds were 58% more frequent on S. gigantea than on S. altissima galls. Similar results were found for sympatric sites, although the difference in attack was only 26% and not significant. We could find no difference in the toughness of galls or the nutritional value of a larva within the gall (in terms of biomass) to explain avian preference for the S. gigantea host race; however, we found that from 1999 to 2000, the S. gigantea race offered a 27–107% higher reward rate (i.e., the probability that a gall harbored a larva of E. solidaginis) than the S. altissima race. Our studies suggest that avian predators can assess a gall’s content prior to pecking it open, preferring galls that are inhabited by both E. solidaginis larvae and the inquiline predator Mordellistena convicta Leconte (Coleoptera: Mordellidae). It is possible that birds have either learned through experience or evolved through natural selection to choose the more profitable S. gigantea galls. Finally, our results suggest that avian predators act against the maintenance of two distinct host races in the midwestern United States.

The predictions of three published models of temperature-dependent egg hatch of the European strain of the gypsy moth, Lymantria dispar L., were compared with observed hatch rates of caged egg masses in Victoria, British Columbia, Canada. Two of the three models gave a good fit to observations. Both of these models considered explicitly the period between oviposition in the summer of one year and hatch of neonates the following spring. When combined with models for temperature-dependent development of larvae and pupae, and adult longevity, the seasonal life history of an entire generation of gypsy moth could be simulated. These composite models predict the seasonal occurrence of all life stages of the insect. The simulated flight period of adult male gypsy moth on Vancouver Island in 1998 compared favourably with observed captures in pheromone traps. A series of gypsy moth generations was simulated using daily temperature inputs reconstructed from climatic normals (period 1961–1990) at various locations on the south coast and southern interior of British Columbia where gypsy moth has been frequently introduced but is not established. These simulations provided estimates of the probability of a persistent population resulting from a predicted stable seasonality of the gypsy moth. The highest probabilities of persistence were in coastal areas along the Strait of Georgia between Vancouver Island and the continental mainland and in southern interior valleys below approximately 500-m elevation (above sea level). Outside these regions, normal climatic profiles resulted in an unstable seasonality for gypsy moth with increasingly late oviposition dates, and subsequent problems in synchronizing initiation and completion of winter diapause with appropriate ambient conditions. The phenology models discussed here can be and were used as decision-support tools either to improve the efficiency of pest management operations (sampling, pesticide applications) or to make better decisions concerning the need for eradication of the gypsy moth in novel environments.

Observations suggesting that mature larvae of some carrion flies (Piophilidae) tend to leap off carcasses during rain motivated an investigation of the ontogeny and possible functions of larval leaping behaviour and larval responses to two stimuli associated with rain: moisture and sound. These behaviours were investigated in larvae of Prochyliza xanthostoma Walker (Diptera: Piophilidae) by means of laboratory and field observations and experiments. Mature larvae left their feeding substrates (rotting meat) in response to either moisture or rattling sound. The response to moisture was exhibited also by immature larvae. Once on the carcass surface, however, only mature larvae leaped off and pupated in the surrounding soil. The response to sound and the ability to leap only appeared late in larval development and were lost in the prepupal stage. Because rain may facilitate larval locomotion on carcass surfaces, and leaping appears to represent a more rapid and efficient means of leaving a carcass than creeping, these responses may reduce the metabolic costs and predation risks experienced by mature larvae moving to pupation sites in the soil. Thus, the ability to leap and the responses to moisture and sound may represent “ontogenetic adaptations” associated with a brief stage of larval development.

Four compounds were identified from female sex-pheromone gland extracts of Acleris fimbriana Merick, an important pest in northern fruit orchards of China, by gas chromatography, gas chromatography – mass spectrometry, and flight-tunnel and field-trapping tests. These compounds were (E)-11,13-tetradecadienal (E11,13-14:Ald), (E)-11,13-tetradecadien-1-ol (E11,13-14:OH), (E)-11-tetradecenyl acetate (E11-14:Ac), and (E)-11,13-tetradecadienyl acetate (E11,13-14:Ac). In field-trapping tests, traps baited with E11,13-14:Ald alone produced the highest trap captures of male A. fimbriana, but the other three individual compounds did not capture any mates. Addition of E11,13-14:Ac to E11,13-14:Ald enhanced trap capture, whereas addition of E11-14:Ac had no effect. A ternary blend of E11,13-14:Ald, E11,13-14:Ac, and E11-l4:Ac in a 6:4:1 ratio captured 7.5 times mean males per trap than virgin females. E11,13-14:OH inhibited trap capture when it was added to E11,13-14:Ald or the ternary blend. This pheromone could be used to monitor populations of A. fimbriana and to control this important pest of fruits in China.

The successful flight takeoff of untethered Colorado potato beetles, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), consists of a strongly sequenced set of behaviors beginning with site location and followed by expansion of the hind wings, rising of the mesothoracic legs, air lifting, and rising of the prothoracic legs, leading to a low angle flight departure. A series of ablation experiments demonstrated that the antennae, the elytra, the mesothoracic legs, and the prothoracic legs all play a significant role in determining the percentage of successful flight takeoffs, as well as the proportion of upward versus downward liftoffs. Flight takeoff of tethered L. decemlineata is positively stimulated by head winds of increasing speeds up to speeds of slightly more than 5.5 m/s. The absence of tarsal contact does not stimulate flight takeoff in L. decemlineata, but tarsal contact interrupts flight. The flight characteristics during liftoff indicate that this species is an in-phase functionally four-winged insect, probably with the hind pair of wings leading the wing beat. Among Coleoptera, the takeoff of L. decemlineata was found to belong to the Melolontha type (classification of Schneider 1975), because the elytra are active.

In Nova Scotia, the whitemarked tussock moth, Orgyia leucostigma Fitch, periodically erupts in outbreaks that typically last 3–5 years. Population changes during a recent outbreak were monitored by means of aerial defoliation surveys and fall egg-mass surveys that were conducted between 1997 and 2001. Severe defoliation was first recorded on approximately 250 ha in 1996. The defoliated area increased rapidly to hundreds of thousands hectares in 1998, after which it sharply declined to about 4700 ha in 2000 and 0 ha in 2001. The total infested area [>0.01 egg masses per three branches of Abies balsamea L. (Pinaceae)] decreased from about 1.4 million ha in 1997 to about 13 500 ha in 2001. Between 1996 and 2001, the infestation involved a cumulative total of 2.4 million ha, covering most of the province. The collapse of larval populations during 1998 was associated with widespread prevalence of a singly embedded nucleopolyhedrovirus (NPV) and Entomophaga aulicae (Reichardt in Bail) Humber (Zygomycetes: Entomophthorales). Sampling of larval populations in late July and August 1998 revealed a widespread and virtually sympatric occurrence of those pathogens in areas that were under defoliation pressure, with infection levels by each pathogen exceeding 75% in many sample sites. Pathogen impacts on larval survival were studied in 1999 in a persisting pocket of severe infestation in Hants County. Larvae were collected every 3 d from balsam fir branch samples between 17 June and 21 July and reared to determine cause of death. The two pathogens together accounted for at least 50% of cohort mortality, calculated as marginal mortality rates according to Royama (2001). Although cohort mortality due to disease on balsam fir was significantly correlated with between-generation reduction in mean egg-mass density, overall pathogen-induced mortality was not high enough to drive the populations into an endemic state, and a moderate infestation persisted into 2000.

Twenty-three isolates of Beauveria bassiana (Balsamo) Vuillemin from different hosts and geographical origins were evaluated under laboratory conditions for various aspects of virulence against 2- to 3-d-old third instars of the obliquebanded leafroller, Choristoneura rosaceana (Harris), a pest of apple, Malus domestica Borkhausen (Rosaceae), and several other orchard crops in North America. When submerged in a solution containing 107 conidia/mL, all B. bassiana isolates caused more than 66% larval and pupal mortality 60 d following treatment. Isolates 14, 16, 1525, 2727, and 2990 caused the highest (80–89%) larval and pupal mortality against C. rosaceana. Relative to the control, isolate 63 significantly increased and isolate 44860 significantly decreased larval development time. Isolates 37, 2727, and 2990 significantly decreased C. rosaceana pupal weight. Isolates 139, 2727, and 2990 significantly decreased the number of emerging females. In view of their larvicidal effects, as well as their carry-over effects on pupae and adult females, isolates 2727 and 2990 showed the best mycoinsecticidal potential against C. rosaceana.

The effect of time of day and age on the amounts and ratios of four pheromone compounds [(Z)-11-tetradecenyl acetate (Z11-14:Ac), (E)-11-tetradecenyl acetate (E11-14:Ac), (Z)-11-tetradecenol (Z11-14:OH), and (Z)-11-tetradecenal (Z11-14:Al)] was compared in azinphosmethyl-susceptible (susceptible) and -resistant (resistant) female obliquebanded leafrollers, Choristoneura rosaceana (Harris). The amounts of all four pheromone compounds varied during the hour before and five hours after the onset of scotophase. The glands of resistant females contained approximately one half the amount of Z11-14:Ac and Z11-14:OH as the glands of susceptible females during the second and third hours of scotophase, and between 50 and 70% as much Z11-14:Al as the glands of susceptible females during the hour before and second to fourth hours of scotophase. The glands of susceptible and resistant females contained similar amounts of E11-14:Ac. The relative amounts of each of the four pheromone compounds were affected by time of day but not by resistance status. There was a negative linear relationship between the amounts of each of the four compounds and female age in both types of females. The amounts of Z11-14:Ac and E11-14:Ac declined at similar rates with age in susceptible and resistant females; the amounts of Z11-14:OH and Z11-14:Al declined more rapidly with age in susceptible than in resistant females. The relative amounts of the four compounds were not affected by female age. Temporal variation in the relative amounts of pheromone in susceptible and resistant C. rosaceana may be associated with similar variation in the emission of pheromone and corresponding temporal variation in the relative attractiveness of the two types of females.

Two mark–recapture experiments and a trap interference experiment were conducted to determine the sampling range and range of attraction, respectively, of Dendroctonus pseudotsugae Hopkins (Coleoptera: Scolytidae) pheromone-baited traps in northern Idaho. To determine the sampling range, either live beetles or logs containing brood were marked with one of four colors of fluorescent powder. Colored beetles or logs were placed along transects oriented away from a central pheromone-baited trap at distances of 50, 100, 200, and 300 m. A release distance of 400 m was added to one mark–recapture experiment during the 2nd year. To determine the range of attraction, a trap interference study was conducted. For this experiment, groups of three traps were oriented in equilateral triangles with distances of 50, 100, 200, and 300 m between the three traps. Distances between traps were changed daily to allow for adequate replication. Mark–recapture studies indicated that most D. pseudotsugae were recaptured from distances less than or equal to 200 m from the pheromone-baited trap. On average, 95% of beetles recaptured were males. Results of the trap interference experiment provided no insight into the range of attraction of D. pseudotsugae pheromones. Natural resource managers should attempt to place pheromone-baited suppression traps within 200 m of target D. pseudotsugae populations. Also, to minimize undesirable beetle-caused tree mortality, traps should be placed as far as possible from live trees that managers wish to protect.

In an effort to develop an efficient monitoring method for the lingonberry fruitworm, Grapholita libertina Heinrich, an economically important pest of lingonberries, Vaccinium vitis-idaea L. var. minus Lodd. (Ericaceae), in Newfoundland, various known sex attractants for other species of the genus Grapholita Treitschke were evaluated for their ability to attract G. libertina moths in field trials in eastern Newfoundland. The chemicals tested were (E,E)-8,10-dodecadien-1-ol acetate (EE8,10-12:Ac), (E)-8-dodecen-1-ol acetate (E8-12:Ac), (Z)-8-dodecen-1-ol acetate (Z8-12:Ac), and (Z)-8-dodecen-1-ol (Z8-12:OH). Field trials in 1996 showed highest attraction to E8-12:Ac, with Z8-12:Ac and Z8-12:OH also being attractive. Trials in 1997 demonstrated that a blend of E8-12:Ac, Z8-12:Ac, and Z8-12:OH at a ratio of 85:10:5, respectively, was attractive to G. libertina males. All chemicals captured significantly more moths than did controls and all moths examined were males indicating these chemicals may be constituents of the naturally occurring female sex pheromone.

Ips paraconfusus Lanier is a vector of the pitch canker fungus, Fusarium circinatum Nirenberg and O’Donnell, in California. Multiple infections of Monterey pine, Pinus radiata D. Don. (Pinaceae), branches and main stems appear to predispose trees to infestation by I. paraconfusus. The effect of cankers produced in response to F. circinatum on oviposition and gallery construction was investigated. Introduction of beetles into artificially induced or naturally occurring cankers was less likely to result in oviposition and resulted in shorter galleries than introductions into logs without cankers. Of all adults that produced eggs, the mean number of eggs per adult was no different in logs with cankers than in canker-free logs; however, the distance across the grain from the introduction point to the first egg was greater for adults introduced into cankers than for adults introduced away from cankers. These results indicate that the pitch canker pathogen has a negative effect on I. paraconfusus, as cankers produced in response to the pathogen are unsuitable for exploitation by the insect.

Honeydew utilization by the ant Lasius niger L. (Hymenoptera: Formicidae), honeydew excretion cost for the aphid Aphis craccivora Koch, and ant protection service for aphids against the lady beetle Coccinella septempunctata L. (Coleoptera: Coccinellidae) were examined in a laboratory. The duration of honeydew utilization by ants increased with increase in aphid density. The presence of ants shortened the residence time of the lady beetle larva on a plant and reduced the proportion of aphids eaten. At a density of 5 aphids per plant, one aphid with ants excreted honeydew at a frequency two times higher than that of an aphid without ants, but not at a density of 100 aphids per plant. Therefore, a larger aphid colony may increase the benefit and decrease the cost of ant attendance.