The elm zigzag sawfly, Aproceros leucopoda Takeuchi (Hymenoptera: Argidae), was reported for the first time in North America during the summer of 2020. Characteristic zigzag defoliation was reported in the province of Québec, Canada, on the community science website, iNaturalist. Field trips conducted to the site resulted in the collection of live specimens (a few larvae and a cocoon from which an adult emerged) and onsite observation of diagnostic defoliation and empty cocoons, confirming the presence of this exotic species in Canada. Subsequent inspection of elm trees by naturalists and scientists in the south of the province led to the conclusion that the species is more widely distributed than first expected and that the invasion is not localised to a small area. Preliminary genetic data pointed to a possible European origin of the Canadian population, but conclusive assignment to source will require examination of more specimens and the collection of reference sequences from different European and Asian populations. This is a good example of the importance of community science in the detection of new invasive species.

A survey of muscid flies from Churchill, Manitoba, Canada, in 2007 yielded 155 species. Some components of species richness and composition of this contemporary assemblage were compared with those of a historical (pre-1965) assemblage, and the contribution of the three collecting methods used in the 2007 survey protocol was evaluated. Estimates of species richness indicated that Malaise traps yielded more species than did pan traps or sweep netting, and that species composition did not differ significantly between Malaise trap and pan trap catches. These results suggest that Malaise traps and sweep netting are adequate methods to survey northern Muscidae. We report little difference in estimated species richness and composition between time periods for material collected by sweep netting. When all material from the 2007 survey was pooled, 87% of the pre-1965 species were collected again in 2007. Most nonoverlapping species between time periods were rare in samples and (or) collected by different methods, suggesting a failure to detect as the most likely explanation for their absence in one assemblage. Nevertheless, the proportion of aquatic and semiaquatic species of Spilogona Schnabl was more than twice as high in the list of species not recovered in 2007 than in the pre-1965 assemblage.

Dung beetles (Coleoptera: Scarabaeidae (Aphodiinae, Scarabaeinae) and some Geotrupidae) provide important ecosystem services on pastures by disrupting and burying deposits of cattle dung. The extent of these services is influenced by the number of individuals and species present, which may differ with habitat type. In the present study, we compared dung beetle assemblages in a mosaic of open grassland and wooded habitats on native fescue pastures in the Cypress Hills of southern Alberta, Canada. Using pitfall traps baited with cattle dung and operated from spring through autumn for two years at each of the two sites, we collected 4944 individuals representing 14 dung beetle species. More individuals and species were recovered in grassland habitat, which was dominated by nonnative species associated with cattle dung. Wooded habitat was dominated by a native species associated with deer dung. Dwellers (species that develop within the dung deposit) comprised 93% of the beetles recovered during the study. Significant variation in annual beetle counts in the two habitats highlights the value of studies conducted over multiple years. These results emphasise the importance of habitat diversity and interspecific habitat preference in structuring dung beetle assemblages on fescue grasslands, which are among the most threatened ecosystems in Canada.

The Orthocentrinae is one of the least-studied groups within Ichneumonidae and possibly a major component of the tropical fauna, encompassing a rich but still obscure diversity. In this first attempt to uncover these biota in Brazil, we surveyed a restricted area within mountain chains in the southeastern region immersed in the Atlantic tropical forest, using several sampling methods along an elevational gradient. Using integrative taxonomy, we found a richness eight times higher than the current number of species known in Brazil, including 13 genera, of which 10 are new to the country. The 127 molecular taxonomic units found represent an increase of at least 50% in species for the Neotropical fauna, confirming the immense gap in taxonomic knowledge of this group in the Neotropics. Analyses of elevational gradient patterns of distribution indicated an increase in species elevational ranges with increasing elevation, supporting Rapoport’s rule. A key including all 14 genera occurring in Brazil is proposed, aiming to facilitate future taxonomic reviews and encourage research on this group. Orthocentrinae is a major component of the fauna and likely to be more diverse in wet lowland tropical forests; however, taxonomic and faunistic studies in tropical areas, including dry forests and savannahs, are needed.

Sampling a cosmopolitan mosquito (Diptera: Culicidae) species throughout its range is logistically challenging and extremely resource intensive. Mosquito control programmes and regional networks operate at the local level and often conduct sampling activities across much of North America. A method for large-scale sampling of two mosquito species using crowdsourcing to network with these local and regional programmes is described. A total of 961 mosquito vector and control districts, health departments, and individual collectors across the United States of America and Canada were contacted in 2011 and 2012 of which 9% positively responded by sending mosquitoes. In total, 1101 unique population samples of Aedes vexans (Meigen) and Culex tarsalis Coquillett were collected throughout their range in these two countries. Aedes vexans outgroup samples were also submitted from Europe and Asia. This is the largest crowd-sourced collection of samples to date.

We studied the effects of agricultural practice on ground beetles, using pitfall traps in field plots and in an uncultivated meadow near Edmonton, Alberta. Ground beetle abundance and species richness were higher in plots operated under an organic farming regime than in those under a chemical regime, but neither crop type [barley (Hordeum vulgare L.), faba bean (Vicia faba L.), barley-pea (Pisum sativum L.) intercrop] nor crop rotation had an effect. Reduced tillage did not significantly change overall carabid activity or species richness but species differed in their response to tillage treatments. The carabid assemblage from an uncultivated field differed conspicuously from assemblages in the crops and fescue. Carabid abundance was highest in the meadow and the fauna was dominated by the exotic species Pterostichus melanarius Illiger. Effects of agronomic practice on carabid assemblages are complex, reflecting the interaction of biological traits of particular species and the combination of agronomic treatments applied.

Despite increasing worldwide interest in host–parasitoid food webs, the parasitoid communities of the high Arctic remain poorly explored. To allow analyses of global patterns, and to detect the effects of ongoing climate change, such data are urgently needed. In this paper, we describe a systematic effort to characterise the high-Arctic Hymenoptera and Diptera parasitoid community associated with Lepidoptera hosts of the Zackenberg Valley (74°30′N, 21°00′W), northeast Greenland. Here, we first sampled adult parasitoids by a combination of Malaise traps, pitfall traps, and, less extensively, yellow pan traps and sweep netting. We then identified the host use of individual parasitoid taxa by rearing a large number of host individuals and species across multiple years. We now describe our preliminary findings on the species diversity of the target community, on trophic links between hosts and parasitoids, and on the sampling effort and techniques needed to characterise the community. We report on 30 local parasitoid taxa representing four families, three of which are species new to Greenland. In describing the community, we make a specific effort to summarise what is known about the taxonomy, phenology, and host use of the component species, to the benefit of future research in the area.

We compared the insect and arachnid species found in spring and summer samples of necrotic tissue of three species of columnar cacti, cardón [Pachycereus pringlei (S. Watson) Britten and Rose], organ-pipe (Stenocereus thurberi Buxb.), and senita [Lophocereus schottii (Engelm.) Britten and Rose] (all Cactaceae), endemic to the Sonoran Desert of North America. A total of 9380 arthropods belonging to 34 species, 23 families, 10 orders, and 2 classes were collected in 36 samples. Arthropod communities differed in composition among host cacti, as well as between seasons. These differences may be a function of variation in host characteristics, such as chemical composition and abiotic factors, such as water content or temperature.

Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a non-native, wood-boring beetle that has caused widespread mortality of ash (Fraxinus Linnaeus (Oleaceae)) in eastern North America. During 2004–2007, we determined whether forest community composition and structure of black (F. nigra Marshall), green (F. pennsylvanica Marshall), and white (F. americana Linnaeus) ash stands influenced their susceptibility to EAB invasion in southeast Michigan, United States of America. There was no relationship between EAB-induced ash decline or percentage mortality and any measure of community composition (tree species diversity, stand/ash density, total basal area, or relative dominance of ash). There was also no relationship between measures of EAB impact (density of EAB signs, ash decline rating, percentage ash mortality, or percentage infested ash) and forest attributes (ash/total stand density, basal area, ash importance, or stand diversity). Decline and mortality of black ash advanced more rapidly than that of white and green ash. Percentage mortality of ash increased from 51% to 93% during 2004–2007. Distance from the epicentre of the invasion was negatively correlated with ash mortality, but this relationship dissipated over time. Stand composition data suggests that ash will be replaced by Quercus Linnaeus (Fagaceae), Acer Linnaeus (Sapindaceae), and Tilia Linnaeus (Malvaceae); such vegetation changes will irreversibly alter the structure and function of these forests.

The identity, richness, and abundance of true flies (Diptera) from the nests of three cavity-nesting raptors (Aves) were investigated in northern Nova Scotia, Canada. After fledging, flies were extracted from the nest material using Berlese funnels within an emergence chamber. Thirty-one species/morphospecies from 14 families were collected, including eight new records for Nova Scotia and two new records for eastern North America.

Understanding the medical and economic impacts of mosquitoes (Diptera: Culicidae) begins with knowing their natural history and distribution, including their association with habitat types, particularly those in which human activity is high. The effects of habitat on shaping the community structure of mosquitoes were studied across periurban habitats on the island of Montréal, Québec, Canada in 2014 and 2015. Mosquitoes were collected from 20 fixed sampling locations in suburban backyards, fields, and forests, using CO2-baited light-emitting diode encephalitis vector survey traps. A total of 184 607 mosquitoes were collected, representing eight genera and 35 species. Suburban, field, and forest sites had different communities of mosquitoes, but differences were not apparent among sites within similar habitat types in nonmetric multidimensional scaling ordinations and permutational multivariate analysis of variance. In both years, the greatest abundance of mosquitoes was collected from field habitat, and the highest species richness, from forests. Suburban sites consistently generated the lowest abundance and diversity. Nearly 75% of the total individuals collected were from three species: Aedes vexans (Meigen), 39%; Coquillettidia perturbans (Walker), 18%; and Aedes canadensis (Theobald), 16%. This research shows that diverse communities of mosquitoes can be found in forests, fields, and backyards, yet the communities between forests differ from more open habitats. Our community analysis reveals that medically important species (e.g., Culex sp.) are more commonly encountered in suburban backyards, yet overall mosquito nuisance potential is greater in forest and field habitats. This information highlights important patterns of mosquito abundance and species occurrence, vital for the development of management programmes.

Lowbush blueberry (Vaccinium angustifolium Aiton (Ericaceae)) production is highly dependent on insect pollination to maximise yields. The current losses in honey bee (Apis mellifera Linnaeus (Hymenoptera: Apidae)) colonies pose a serious threat to the blueberry industry, raising interest in alternative pollinators. Abundance and diversity of native pollinators usually decreases with distance from natural habitats. In this study, we evaluated the effects of distance from wooded habitats such as windbreaks and forest borders on the presence of native pollinators in blueberry fields in Lac-St-Jean (Québec, Canada). Four treatments were compared: single-row, double-row, natural windbreaks, and forest borders. Pan-traps were placed at 5, 30, and 60 m from the windbreak or forest border. A total of 3878 native pollinators were collected and 81% were ground-nesting bees. The forest border was the only treatment with higher abundance and species richness on the periphery (5 m) of the field than at further distances, supporting the hypothesis that the presence of pollinators is favoured by habitats potentially offering more abundant and diverse nutritional resources. Our overall results reveal that native pollinators are distributed quite homogeneously in blueberry fields, suggesting that windbreaks are beneficial to native pollinator communities.

The arthropod and annelid fauna of a series of small, acidic pools in a domed, ombrotrophic bog on the Avalon Peninsula, Newfoundland, was studied over the ice-free season of 1986. Pools were assigned to four classes on the basis of their surface area (<1; 1.1–10; 10.1–100; >100 m2) and at least two 1-m2 (entire pool if area <1 m2) substrate samples, plankton samples, and moss samples were taken from pools of each size class biweekly. One hundred and thirty-one taxa, most identified to the species level, were collected. Taxa varied in abundance between pools of various size classes and, using Cluster Analysis and TWINSPAN, two principal communities were identified. Oligochaetes, beetles, and mosquitoes dominated small, astatic pools and odonates, chironomids, and several other taxa predominated in large, stable, vegetated pools. Water level stability is postulated to be the principal factor determining this community structure. Within large pools, odonate larvae were the dominant predators and comprised the majority of the standing crop. Odonate larvae have life cycles of 2 or more years; their slow growth is probably due to prey limitation. Odonate larvae potentially exert a powerful predation pressure within the large pool community, and may be the principal biotic factor determining abundance and distribution of prey taxa within the bog pool system.

We review the existing literature on patterns of moth (Lepidoptera) species richness and community composition in northeastern Nearctic forest ecosystems across hierarchical scales ranging from individual trees to entire managed ecoregions. Moths are species-rich in northeastern forests of North America, with the most diverse families being Noctuidae and Geometridae. Individual trees and forest stands, however, are often dominated by few species. Climate, stand age, disturbance regime, and landscape heterogeneity are significant predictors of abundance of dominant species. Most other moth species in the regional pool are patchily distributed and appear to occur regularly at very low abundance. Moth communities respond predictably to forest-management practices, and the outcomes of postmanagement response are largely driven by changes in the plant community. Significant reductions in moth species richness and changes in community composition are correlated with clear-cut harvesting, whereas selective logging appears to cause more moderate changes in moth community structure. Broad-scale effects of forest fragmentation on moth communities in unglaciated regions are best described by species replacement rather than species loss; moth species richness decreases slightly across a gradient of fragment sizes, but shifts in moth community composition are more important, especially in the relative importance of herbaceous-plant-feeding species in large and small fragments. Species that appear to be most sensitive to timber management or habitat loss are dietary specialists as larvae, dispersal-limited as adults, or dependent on commercially valuable tree species such as oaks, Quercus L. (Fagaceae). Restored forest stands tend to converge in terms of lepidopteran species dominance and diversity among stands, suggesting that the long-term consequences of timber management or habitat loss include a significant reduction of regional β-diversity. Finally, future research on forest Lepidoptera should include an emphasis on understanding the role of urban woodland habitat in retaining viable and diverse moth communities and how the spatial pattern of timber harvest affects the relative magnitude of α- and β-diversity components within a given ecoregion.

The world is astoundingly variable, and organisms – from individuals to whole communities – must respond to variability to survive. One example of nature’s variability is the fluctuations in populations of spruce budworm, Choristoneura fumiferana Clemens (Lepidoptera: Tortricidae), which cycle every 35 years. In this study, we examined how a parasitoid community altered its parasitism of budworm and other caterpillar species in response to these fluctuations. Budworm and other caterpillar species were sampled from balsam fir (Pinaceae) in three plots for 14 years in Atlantic Canada, then were reared to identify any emerging parasitoids. We found that the parasitoid community generally showed an indiscriminate response (i.e., no preference, where frequencies dictated parasitism rates) to changes in budworm frequencies relative to other caterpillar species on balsam fir. We also observed changes in topology and distributions of interaction strengths between the parasitoids, budworm, and other caterpillar species as budworm frequencies fluctuated. Our study contributes to the hypothesis that hardwood trees are a critical part of the budworm–parasitoid food web, where parasitoids attack other caterpillar species on hardwood trees when budworm populations are low. Taken together, our results show that a parasitoid community collectively alters species interactions in response to variable budworm frequencies, thereby fundamentally shifting food-web pathways.

Surveys were conducted to determine the parasitoid communities associated with the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham), an important invasive pest of canola in Ontario and Quebec, Canada. More than 18 species of Chalcidoidea (Hymenoptera) were associated with this pest through mass rearings from canola siliques. In southwestern Ontario, the most abundant species were a species of Chlorocytus Graham (23.6%–48.6%), Lyrcus perdubius (Girault) (0%–53%), L. maculatus (Gahan) (2.8%–14.7%), and species of Pteromalus Swederus (0.6%–23.1%) (Pteromalidae). In contrast, the most abundant species in Quebec were Trichomalus lucidus (Walker) (Pteromalidae) (33.3%–56.4%), unidentified Eulophidae (2.1%–39.1%), Mesopolobus gemellus Baur and Muller (Pteromalidae) (1.3%–21.4%), and Necremnus tidius (Walker) (Eulophidae) (11.5%–19.3%). In the Ottawa, Ontario, area, parasitoids were first recovered in 2008, and Trichomalus perfectus (Walker) (Pteromalidae), M. gemellus, and species of Pteromalus were most prevalent. Mesopolobus gemellus and T. perfectus are reported in North America for the first time. Although existing communities appear to provide substantial parasitism (e.g., 6.3%–26.3% in 2006), species composition varies among years and differs from that in other regions in North America. Thus, parasitism levels and parasitoid communities of the cabbage seedpod weevil should be monitored to assess whether these will increase or there is a need to introduce more host-specific species from Europe that could provide greater mortality.

Agricultural practices affect the biotic and abiotic conditions thatdetermine food and shelter for carabid beetles (Coleoptera: Carabidae). Wehypothesised that carabid communities would respond differently to 18 yearsof contrasted cropping practices in cereal-based rotations. We measured theeffects of tillage (MP: moldboard plough; CP: chisel plough; NT: no-till)and previous crop sequence (cereal monoculture versuscereal–forage/cereal–oilseed rotation) on carabid beetle activity density,diversity, and community structure in corn (Zea maysLinnaeus, Poaceae) at La Pocatière, Québec, Canada. Carabid beetles weresampled monthly from May to September 2006, using pitfall traps. Although 19carabid species were observed, assemblages were dominated by Harpalus rufipes (De Geer), particularly in the secondhalf of the season. Multivariate analyses indicated a strong affinity ofcarabid species for the NT treatment throughout the season. Crop sequenceand tillage had no effect on diversity (Shannon's H′ ≤ 1.3)and evenness of carabid assemblage, but species richness and activitydensity were greater in NT than in tilled systems. Peak activity density ofdominant species occurred at different times during the season, generally inaccordance with preferred breeding season. Many species had greater activitydensity in NT than in tilled treatments. Because of their granivorousfeeding habit, carabid populations such as that of H. rufipes could be an important asset to NT, given the limitedweed management options available for this system.

Species richness and relative abundance of arthropod taxa from an Upper Cretaceous (Campanian: 75 Mya) amber deposit in Alberta are described. About 130 hexapod species have been recognized to date from this deposit, making it the most diverse Cretaceous insect assemblage so far known. Taxa present, in order of abundance, are Hemiptera (66 specimens per kg), Diptera (28), Acari (21), Hymenoptera (13), Aranaea (12), Psocoptera (4), Coleoptera (2), Blattodea (1), Thysanoptera (1), and Trichoptera (0.6). Representatives of Lepidoptera, Collembola, Dermaptera, Mantodea, Phasmatodea, and Ephemeropteraare are also present. In the total of 65 identified families, 15 are extinct. Only one of about 77 genera identified in this deposit is extant. All recognized species are extinct. In comparison, virtually all families reported from Baltic and Dominican Republic ambers are extant, as are the majority of the genera. Morphology and feeding structures are well within the variation seen in modern insects. It is hypothesized that the taxonomic structure of modern insect communities was well established before the end of the Cretaceous and that the structure and interrelationships of insect guilds were also very similar to those of today.

Several Drosophila species (Diptera: Drosophilidae) have become serious economic pests of berry and soft-skinned stone fruits around the world. Prominent examples are Drosophila suzukii (Matsumura), D. melanogaster (Meigen), D. hydei (Sturtevant), and D. immigrans (Sturtevant). Information on the biology and ecology of Drosophila is important for a better understanding of these important fruit pests and, ultimately, for fruit protection. In this study, the gut bacteriomes of these four Drosophila species were surveyed and the differences among bacterial communities were characterised. The 16S rRNA genes of gut microbes were sequenced by Illumina MiSeq technology (Illumina, San Diego, California, United States of America), followed by α-diversity and β-diversity analyses. The results show that bacteria of the family Enterobacteriaceae (Kluyvera and Providencia; phylum Proteobacteria) dominated all four Drosophila species. Specific dominant gut bacterial communities were found in each Drosophila species. The dominant families in D. melanogaster and D. suzukii were Enterobacteriaceae, Comamonadaceae, and Acetobacteraceae. In the intestine of D. hydei, Enterobacteriaceae had a proportion of 56.99%, followed by Acetobacteraceae, Spiroplasmataceae, and Bacillales Incertae Sedis XII. In D. immigrans, besides Enterobacteriaceae, Alcaligenaceae, Flavobacteriaceae, Xanthomonadaceae, Comamonadaceae, and Sphingobacteriaceae also had high relative abundance. These data expand current knowledge about the putative function related to gut microbes – for example, the metabolism of carbohydrates, amino acids, inorganic ions, lipids, and secondary metabolites. This knowledge provides a basis for further metatranscriptomic and metaproteomic investigations.

Community organization is defined as the mean number of trophic links connecting species of different trophic levels in a community. For the special purposes of this paper, competition is assumed to occur whenever two species are known to eat the same food species. Community stability is defined as the reciprocal of the mean, for all species, of the standard error of logarithms of annual collection sizes. It is thus a measure of stability over time of the species populations in a community. Several authors writing about the relationship between community organization and community stability have insisted that the stability of a complex ecological system increases with the number of avenues by which energy can flow through it. This theory does not seem consistent with the observation that some insect pest species of notorious instability are attacked by a great number of entomophagous species. In this paper we seek additional evidence bearing on the relationship between community organization and stability, using computer analysis of data collected by the Canadian Forest Insect Survey on forest Macrolepidoptera and their food plants. After considering our results, and those of other workers, we postulate the following hypothesis. Stability at any herbivore or carnivore trophic level increases with the number of competitor species at that level, decreases with the number of competitor species that feed upon it, and decreases with the proportion of the environment containing useful food. If this hypothesis is valid, too much competition in the entomophagous trophic level will not allow the species in that level to be instable enough to control an unstable pest. Therefore, the best type of biological control agent is one that has no direct competitor species. Also, the most unstable biological control agents, and hence those capable of controlling an unstable pest, will be polyphagous.