Red and white clovers, Trifolium spp., were grown in nitrogen-poor soil containing cadavers of larval Galleria mellonella (L.) that were infected with Steinernema carpocapsae (Weiser) and its symbiont Xenorhabdus nematophilus Poinar and Thomas. Growth and root nodulation were not affected by the nematode treatment, leading us to conclude that they would not be impaired through the action of antimicrobial agents produced by Xenorhabdus spp. present in soils because of Xenorhabdus-infected insect cadavers.

Estimates of global species richness for insects are based upon extrapolations from “known” to unknown faunas and hence rely upon accurate counts of species for the referrent taxon or region. The number of reference species depends upon the species concepts employed by workers in that group combined with the degree to which nonstandard (i.e. nonmorphological) approaches have been used. Genetic data are more directly applicable to the detection of the apparent absence of gene flow, which lies at the heart of any species concept, than is morphological information. But what criteria can be used as a practical guide to suggest the absence of gene flow and define species-level units? Minimally, the phylogenetic species concept requires that there be one fixed difference between two samples for them both to be considered discrete species. The assumptions accompanying this definition include the survey of sufficient geographic locations, loci, and individuals. Based upon six studies of mostly widespread, readily identifiable and well-investigated bee “species”, we estimate that the number of species currently recognised may underestimate the true figure by half (although for at least two of the studies localities have been undersampled and more collections are needed). Even when examples for which there are fewer than five fixed differences between samples are removed from the data set, the number of recognised species increases by perhaps as much as 50% (the same caveat regarding undersampling of populations still applies). We suggest that the presence of morphologically unrecognised species may be more common among widespread, easily identified “species” than is generally accepted. Whether or not similar levels of species underestimation apply to other faunas, such as tropical rainforest canopy beetles, remains to be investigated.

Predation experiments were conducted to identify a predator with the capacity to control the tomato russet mite, Aculops lycopersici (Massee) (Eriophyidae), in greenhouse tomato crops. The efficiency of four predatory mites species was evaluated at the individual level in the laboratory: the tydeid Homeopronematus anconai (Baker) and the phytoseiids Phytoseiulus persimilis Athias-Henriot, Amblyseius cucumeris Oudemans, and A. fallacis Garman. The first three species had already been suggested as potential control agents. Predation by P. persimilis was essentially zero on tomato russet mite, whereas H. homeopronematus failed to develop to the adult stage when fed solely with this prey. Amblyseius cucumeris developed successfully on tomato russet mite but failed to reproduce. Only A. fallacis appears to possess several of the biological attributes required to control the tomato russet mite. This species attacks all stages of the pest and displays excellent survival (.92%), adequate rate of development (6.3 days at 22 °C), and good reproductive capacity in the presence of A. lycopersici.

Palaeoleptochromus schaufussi (gen.nov., sp.nov.) is the first antlike stone beetle (Coleoptera: Scydmaenidae) to be described from Cretaceous amber. The piece of amber containing this specimen was collected in an area near Grassy Lake, Alberta, Canada, and is dated 79 million years old. This new genus is placed within the Mastiginae and is most likely the sister taxon to the recent Neotropical genus Leptochromus Motschulsky.

Records of bumble bees from four collecting trips (1977, 1978, 1988, and 1994) in northern Britain show apparent changes in the incidences of two species. Until 1988, Bombus muscorum (Linnaeus) and Bombus pascuorum (Scopoli) were found in the counties of Cumbria, Durham, and North Yorkshire. Only B. muscorum was found in the Orkney Islands in 1978. In 1994, however, B. pascuorum was found abundantly in all of these areas, and in the Orkney Islands we could find only a single B. muscorum. From these data, B. pascuorum appears to have been replacing B. muscorum in some parts of northern Britain.

Megarhyssa atrata F., the largest hymenopteran parasitoid known, is found in the holarctic. The stylus of its ovipositor can reach a length of 142 mm, the longest of all known genitalia in Arthropoda. This pimpline parasitizes its host, Tremex columba L., at a great depth in wood. Valvulae 3, which are always shorter than the stylus, are characterized on their outer side by abundant trichoid sensilla of three different types, and on their inner side by a dense layer of cuticular spines probably used in cleaning and shielding the stylus while at rest. The joint region between stylus and abdominal segments is richly equipped with mechanoreceptive trichoid and campaniform sensilla. The ovipositor canal is located between the two valvulae 1 which are separate for their entire length and supported proximally by the two valvulae 2 which are joined to each other from the base. The distal end of the stylus, shaped like an indented lancet, has secretory pores, the first such to be observed in Hymenoptera, from which accessory gland secretions flow. These secretions reach the end of the stylus by intravalvular canals in valvulae 1 and 2. These substances, which may cause cell lysis and also act as lubricants, can accumulate among the tens of thousands of cuticular formations distributed along the stylus which are thought to be surface storage cavities for the secretions. The sensory equipment of the stylus consists of six rows of approximately 200 mechanoreceptive campaniform sensilla. The ovipositor of M. atrata is thus characterized by almost exclusively mechanoreceptive sensory equipment; chemical stimuli appear to be monitored by two types of trichoid sensilla on valvulae 3. The finding that secretory pores occupy exactly the same sites as chemoreceptors in Ichneumonidae, Chalcidoidea, and Proctotrupoidea demonstrates the importance of studying the ovipositor of this parasitoid adapted to withstanding extreme pressures as it penetrates deep into wood.

Larval growth and pupal parameters of the forest tent caterpillar (Malacosoma disstria Hübner) reared on the foliage of two host trees (Populus tremuloides Michx. and Acer saccharum Marsh.) and one nonhost tree (Acer rubrum L.) were quantified. This was achieved by undertaking a larval development bioassay under controlled laboratory conditions, but using fresh leaves collected in two field seasons. Larvae fed foliage of P. tremuloides grew exponentially and began to pupate after 3 weeks. Larvae fed with A. saccharum gained significantly less weight and had a reduced number of larvae pupate, and the pupae weighed significantly less than their counterparts fed on P. tremuloides. All larvae that were fed the foliage of A. rubrum died within 2 weeks. A nutritional utilization bioassay with fourth-instar larvae revealed that the foliage of A. saccharum has a growth-inhibitory component, whereas that of A. rubrum is antifeedant. Reasons are discussed for the discrepancy between the many reports of A. saccharum being a food host for M. disstria in the field and the laboratory results.

The invasion of a Douglas-fir seed orchard by host-specific seed chalcids immigrating from the surrounding plantations of Douglas-fir has been monitored for a 10-year period. The orchard cone crop was entirely harvested every year to prevent the establishment of a resident chalcid population. Over the 10 years the percentage of infested seeds resulting from the immigration of seed chalcids ranged from 0.88 to 91.0%. A model to forecast the importance of annual seed orchard infestation by immigrating populations is proposed. This model is based on passive diffusion of females emerging in the surrounding plantations with a downwind drift. Only a few plantations located within a radius of 5 km from the orchard appeared to contribute significantly to orchard infestation. Settlement of Douglas-fir orchard in regions with low density of conspecific trees and annual harvest of cones are suggested to limit the importance and regularity of seed chalcid damage.

We assessed enzyme variability in a solitary leafcutter bee, Megachile rotundata (Fabricius), and found sufficient variability to compare relatedness among progeny in a nest in two samples: (1) nests with an associated adult female (putative mother) and (2) nests with out-of-sequence male progeny (M. rotundata, like most cavity-nesting solitary aculeates, usually provisions all female cells in a nest before any male cells). Estimates of relatedness from nests with associated adult females were consistent with the progeny in a nest being closely related and the offspring of a single, once-mated female. The relatedness estimates from nests with out-of-sequence males were all much lower, suggesting some combination of nest parasitism, nest usurpation, nest abandonment, and multiply mated females in these nests. The high levels of relatedness among female progeny in the first sample, as expected for full sisters in a haplodiploid system, are considered with respect to the evolution of social behaviour in the Hymenoptera. Besides higher estimates of relatedness, the nests with an associated female also had a lower male:female sex ratio than did nests with out-of-sequence males.

Species richness of arthropods in northern temperate coastal rain forests far exceeds previous estimates, and the functional significance that these species play in ecosytem processes remains largely unknown. Examination of several species, many of which are not yet described, indicates that these intact ancient rain forests are structurally complex and act as reservoirs for biological diversity. Forest harvesting and resulting fragmentation affects arthropod diversity by altering key patterns of natural processes which are inseparably linked to habitat diversity. Consequences for arthropods may vary but those species which are endemic or inseparably linked to habitat features found only in these forests are particularly vulnerable to fragmentation-induced changes. Several important questions arise. What are the implications of forest fragmentation on ecological processes? What role does dispersal play in arthropod population viability? Given the immense biodiversity of arthropods, what are the functional roles that the species play in these forests and how are these changed when forests are harvested? The lack of empirical evidence makes it difficult to answer these questions and to quantify the functional roles of arthropods in these ecosystems.To address these questions, I suggest that studies should not rely on single-species approaches and the measurement of diversity (i.e. species richness and abundance) but should focus on addressing the functional roles of forest arthropods. To move beyond the basic description of pattern I suggest that studies concentrate on describing species assemblages while including dynamic processes such as dispersal into the framework of how we think about arthropods in ancient forests. The use of feeding guilds in the development of predictive models may give us an understanding of these factors and provide information that could be used to examine functional patterns in community structure.

Eudorylas alternatus (Cresson) is recorded as a parasitoid of Cuerna striata (Walker) (Homoptera: Cicadellidae, Cicadellinae), providing the first known example of a big-headed fly parasitizing a cicadelline. Rearing methods and parasitism rates are discussed, and a summary of known Nearctic pipunculid–host associations is presented along with an overview of big-headed fly natural history.

The effect of light intensity and wind speed on the body temperature of larvae and adults of the Colorado potato beetle (Leptinotarsa decemlineata (Say)) was studied in the laboratory. At a light intensity of 0.95 kW m−2 and without wind, the body temperature of larvae and adults was respectively 9.3 and 18.2 °C higher than air temperature. The temperature difference between the body temperature of larvae and adults and the air temperature increased linearly with an increase in light intensity. Wind speed had an important effect on the rate of increase of the body temperature as a function of light intensity in both larvae and adults. Our results demonstrated that the energy balance of larvae and adults differs.

The preference of the predatory midge, Feltiella acarisuga (Vallot), for adult male and female twospotted spider mite, Tetranychus urticae Koch, was examined using functional response models. The midge exhibited a type-II functional response to each prey. Handling time was estimated to be much higher for the female mites than for the males (1.52 vs. 0.40 h). Estimated instantaneous search rates for the female and male mites were similar (1.32 vs. 1.28). A preference index of 1.03 was calculated using the ratio of the instantaneous search rates. Feltiella acarisuga was found to exhibit no preference for either female or male mites; when both prey were present in equal numbers, midge larvae killed as many females as males.

Two naturalized populations and two planted populations of Rosa rugosa Thunb. were studied with respect to chalcid seed wasp infestation. Megastigmus nigrovariegatus Ashmead was found in hips from planted R. rugosa in Halifax and Dartmouth, Nova Scotia, but not from bushes at naturalized sites. The percentage of infested hips at the Halifax and Dartmouth locations was 26 and 31%, respectively. The percentage of infested achenes within a single hip varied widely from 3 to 79% at the Halifax site and 7 to 60% at the Dartmouth site.Adult emergence was over 75% successful when achenes were over 2 mm in diameter but less than 15% for smaller achenes. The exit hole on the achene faced the outer wall of the hip. Adults emerged later in Nova Scotia than in the United States and between 59 and 72% were female. More than one adult wasp was observed ovipositing on a single hip.

A survey of 65 populations of Colorado potato beetle, Leptinotarsa decemlineata (Say), from locations across Prince Edward Island in 1993 indicated that insecticide resistance was widespread, but was most prevalent in the western and central potato-producing areas. Of the populations surveyed, 31, 26, 19, and 4% were classified as resistant to permethrin, carbofuran, azinphos-methyl, and endosulfan, respectively. Of 53 populations surveyed for resistance to these four insecticides, 13, six, four, and one of the populations were classified as resistant to one, two, three, and four insecticides, respectively.

The larval morphology of the dytiscid genus Oreodytes Seidlitz was investigated through a detailed analysis of 16 Nearctic and two Palearctic species. Many structural features, especially those of chaetotaxy and porotaxy of head capsule, head appendages, legs, last abdominal segment, and urogomphi, were found to be useful for taxonomic and phylogenetic comparisons. Within the tribe Hydroporini, it is proposed that Oreodytes shares a monophyletic origin with the genera Deronectes Sharp, Scarodytes Gozis, Nebrioporus Régimbart, and Stictotarsus Zimmermann. A tentative phylogenetic reconstruction of the genus Oreodytes, based on 29 larval characteristics, is provided. The classification of members of Oreodytes indicated by larvae is shown to be only partly reconcilable with the one indicated by adults. Once subdivided into three species-groups, Oreodytes now comprises four species-groups: the O. picturatus, O. obesus, O. scitulus, and O. quadrimaculatus species-groups. Oreodytes quadrimaculatus was found to share a monophyletic origin with the members of the O. picturatus and O. scitulus species-groups. The taxonomic status of the genus-name Neonectes J. Balfour-Browne is reconsidered as the larvae of N. natrix (Sharp) and N. babai Satô are revealed to be most similar morphologically to members of the O. scitulus species-group.

Using gas chromatography and gas chromatography – mass spectrometry analyses of sex pheromone gland volatiles, we identified E- and Z-11-tetradecenals (E:Z-11-14:Aid) in an 85:15 blend of E:Z as the primary sex pheromone components of Croesia semipurpurana (Kearfott). Similar chemical analyses of sex pheromone gland extracts indicated the presence of the congeneric acetates (85:15 E:Z-11-14:Ac) and their saturated analogue (14:Ac); in addition, 85:15 E:Z-11-14:Alds were present at 5% of the acetates. The E:Z-11-14:Alds alone elicited trap capture; admixtures of saturated and unsaturated acetate analogues exhibited no significant synergistic or inhibitory effects. PVC rods with an 85:15 E:Z-11-14:Ald blend is recommended as a trap bait for monitoring population trends. It is unknown whether or not the components identified here represent the complete pheromone blend of this species; data from traps suspended 1.5 m above the ground versus those suspended 10 m above the ground suggest that future field studies may need to be conducted with traps positioned in the tree canopy.

Lathrolestes nigricollis (Thompson) (Hymenoptera: Ichneumonidae) was released in New England against Fenusa pusilla (Lepeletier) in 1979–1980 and again in 1989–1990. By 1991, the parasitoid was widely established in southern New England. From 1979 to 1990 the commonness of leafminers at the original release site in the first generation declined from 50–54% of leaves mined to under 3%. Over 4 years at five sites, parasitism of larval birch leafminers increased between leafminer generations from 10.3% (G1) to 27.6% (G2) to 39.2% (G3). In Massachusetts, parasitism decreased (from 28 to 14%) with increasing distance from the original release site, while corresponding damage increased (from 6% of leaves mined to 33%). In areas local to the original release site (<4 km) parasitism has reduced damage from birch leafminer to inconsequential levels. Some sites in other parts of southern New England, particularly roadside sites, still have high levels of mined leaves in spite of the parasitoid’s presence in the general area.

The formulated product of the insect-molting hormone analog, tebufenozide (MIMIC 240LV), and two aqueous formulations of Bacillus thuringiensis subsp. kurstaki, ABG6387 and ABG6414, were aerially applied over prethinned commercial stands of balsam fir infested with the eastern hemlock looper. MIMIC® was applied once at the rate of 65.1 g active ingredient (ai) in 1.86 L/ha and twice at the rate of 33.4–35.4 g ai in 1.91–2.02 L/ha. The formulations of B. thuringiensis were applied twice at rates of 19.3–24.1 billion International Units (BIU) in 1.54–1.93 L/ha for ABG6387 and 33.2–36.0 BIU in 1.67–1.80 L/ha for ABG6414.

Nine of the 10 plots treated with the single application of MIMIC showed reductions resulting from treatment, ranging from 3 to 93% within 9–11 days and 8 to 100% after 3 weeks. Plots treated twice with the lower dosage of MIMIC generally had larval population reductions of over 50% within 9–11 days of treatment and over 60% 3 weeks after treatment. For both treatments with MIMIC, plots with poor efficacy were clearly associated with low foliar deposition of the active ingredient. Overall, the results suggest that deposits of tebufenozide of less than 1.5 μg/g foliage do not give acceptable control of hemlock looper. Pupal population reductions resulting from treatment ranged from 8 to 99% for plots treated with the single application and 76 to 100% for plots treated twice at the half-dosage. Ground assessments of defoliation occurring after treatment ranged from 10 to 51% (year-old foliage) and 0 to 16% (current-year foliage) for the plots treated once, and 1 to 33% (year-old foliage) and 0 to 8% (current-year foliage) for the plots treated twice at the half-dosage. Thirty-five to 65% of year-old foliage and 15–39% of current-year foliage was defoliated in untreated check plots.Reductions resulting from treatment by ABG6387 ranged from 27 to 91% 10 days after the first application, from 73 to 99% 8 days after the second application, and from 90 to 100% for pupae. Plots treated with ABG6414 had larval population reductions from 76 to 93% 10 days after the first application and from 98 to 100% 7 days after the second application. No pupae were recovered in the plots treated with ABG6414. Defoliation assessed from ground level was less than 5% in the plots treated with ABG6387 and ABG6414 compared with defoliation of 10–29% of year-old foliage and 8–12% defoliation of current-year foliage in the check plots.

The Collembola of commercial balsam fir [Abies balsamea (L.)] forests of western Newfoundland were surveyed through Berlese funnel extraction of samples taken from soil and various forest microhabitats and through pit-fall trapping. A total of 64 species representing 30 genera was collected. Twenty-three genera and 47 species are new records for the Island of Newfoundland; eight additional species were identified to genus level only. For each species, the abundance in soil samples and distribution among microhabitats are described. The fauna of Newfoundland is about equivalent in species richness to that of Quebec and almost twice as rich as the recorded fauna of the Maritime Provinces. Few species are common to the three areas. However, this probably reflects the general paucity of knowledge of Canadian Collembola rather than indicating strong regional patterns in faunal composition.