Freshwater biodiversity is increasingly at risk wherever land uses such as agriculture exert multiple stressors that degrade habitat quality. Although stream macroinvertebrates act as bioindicators for monitoring these impacts, their responses are context-specific: examining drivers of community composition is therefore important to understand the results of monitoring efforts. In a primarily agricultural landscape, 15 sites across the Sydenham River watershed, Ontario, Canada, were assessed for in-stream habitat quality and stream macroinvertebrate diversity. We predicted that community assemblage would be driven by differences in surficial geology across branch (east branch versus north branch) and catchment position (main stem versus tributary). We found that the main stem of the east branch was characterised by significantly higher proportions (P = 0.053) and abundance (P = 0.038) of Ephemeroptera–Plecoptera–Trichoptera (EPT) taxa than north branch sites were, and sites in the east and north branch tributaries were characterised by significantly lower Hilsenhoff Biotic Index (HBI) scores (P = 0.088). Redundancy analysis found that substrate size was the main driver of community composition, generating a model that described these patterns across branch and catchment position. Our findings suggest that EPT abundance and HBI scores were the variables that were most effective at revealing differences in stream communities due to agricultural impacts and that sediment size is an important driver of these patterns.

The invasive pea leaf weevil, Sitona lineatus (Linnaeus) (Coleoptera: Curculionidae), damages field peas, Pisum sativum Linnaeus (Fabaceae), and faba beans, Vicia faba Linnaeus (Fabaceae), on the Canadian prairies. We used semiochemical-baited pitfall traps to monitor and detect S. lineatus range expansion and capture associated predaceous ground beetles (Coleoptera: Carabidae) in pulse-growing regions across Alberta. Traps captured male and female S. lineatus in all pulse-growing regions in the spring and fall, including a first record of S. lineatus in the Peace River region of northwestern Alberta. Pheromone-baited traps captured more weevils than unbaited traps did, and the addition of host plant volatiles did not increase the catch. More weevils were captured in traps in pea fields compared to in faba bean fields. Rubber septa lures released more pheromones and attracted a similar number or more weevils to traps than microcentrifuge tube lures did. Ground beetle capture was not affected by semiochemical baits targeting S. lineatus. Ground beetle diversity varied by region and collection period, but the most frequently collected species was Pterostichus melanarius, a potential predator of S. lineatus. This study shows that pitfall traps baited with rubber septa pheromone lures can be used to monitor new and expanding S. lineatus populations, as well as potential natural enemy communities.

As urbanisation continues to increase, terrestrial arthropod diversity declines. Urban green spaces represent unique opportunities to preserve arthropod diversity in urban environments. We quantify how ground-dwelling arthropod communities vary both seasonally and across three differently maintained stormwater infiltration basins in Ellisville, Missouri, United States of America. One basin was routinely mowed, a second was mowed only seasonally, and a third was intentionally planted to attract pollinators and was not mowed during this study. We expected higher plant diversity to correlate with higher arthropod diversity. Therefore, we expected the unmowed basin to have the highest levels of arthropod diversity and abundance and the mowed basin to have the lowest. Four collection periods spanned spring, early summer, late summer, and fall. During each collection period, five pitfall traps were placed throughout each basin for 48 hours. In total, 5686 specimens were collected and identified, representing 59 families. Arthropod communities did not vary across basins or collection dates, largely contrasting with existing literature. The results of this study do not indicate that different mowing regiments in infiltration basins will affect the ground-dwelling arthropod communities at a family level, although the effect on species-level diversity remains to be investigated.

Mantids are influential generalist predators in terrestrial systems. Therefore, large mantid species like the European mantid, Mantis religiosa (Linnaeus, 1758), are often used by humans and purposefully introduced as a form of biocontrol, greatly expanding their geographic ranges. However, mantids are rarely recorded in marine systems. In this study, we present an observation of European mantids living in a salt marsh and actively moulting in the vegetation in Elkhorn Slough, in Monterey Bay, California, United States of America. Not only are these European mantids a nonnative species, but every observed individual was a flightless juvenile, meaning they hatched nearby. Although mantids are not usually associated with intertidal ecosystems, there are multiple potential reasons that mantids would be drawn to salt marshes, including food, potential for camouflage, and lower predation pressure. The addition of a generalist predator could produce a complex mix of positive and negative impacts on the marsh itself and, given the importance of marsh systems, these possible effects warrant further study.

Seven species of Polydrusus Germar weevils (Coleoptera: Curculionidae) occur in the United States of America and Canada, three of which are introduced from Europe, are polyphagous, and may be displacing native weevil fauna in select areas of North America. We review host plant information for these species and provide distributional maps for each. We also present results on the seasonal phenology and sex ratios of two nonnative species, Polydrusus impressifrons (Gyllenhal) and Polydrusus formosus (Mayer), recorded in 2020 and 2021 in two orchards of hybrid hazelnuts (Betulaceae) in Minnesota, United States of America. These two species may present an episodic threat to the burgeoning hybrid hazelnut industry due to their ability to damage buds, foliage, and roots of hardwoods. We found that adults of these two species began emerging in late May of each year and remained present until mid-July. We found higher numbers of P. formosus than of P. impressifrons on hazel plants. Sex ratios of both species were generally between 50–60% male. We supply a compendium of species descriptions that (1) distinguishes between native and nonnative species and (2) identifies the sex of nonnative species. This research contributes to work on the ecology of Polydrusus, conservation of native species, and the management of tree crops.

Using aerial sketch map data spanning more than 1 000 000 km2 across Canada, I use cluster analysis to show that outbreaks of forest tent caterpillar, Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae), through the 20th century have occurred regularly every decade or so; however, there are two distinct aspects to the patterning of outbreaks. The dominant mode of variability is a nonrecurring pattern of singular spike anomalies, lasting just a few years, that are regional in extent but are not synchronised across the country. The regional time series derived from cluster analysis that are dominated by these singular spike eruptions exhibit extreme skewness and kurtosis, are not stationary in mean or variance, and are not amenable to classical time-series analysis. Although these regional-scale eruptive anomalies tend to occur periodically in aggregate, their central location always varies in an unpredictable manner, resulting in aperiodic local behaviour. Range-wide periodicity is thus an emergent property from asynchronous, aperiodic eruptions aggregated across regions. The second mode of variability is a low-amplitude fluctuation of weak periodicity that is weakly synchronised across the country. These observations support a hybrid cyclic–eruptive theory of outbreak occurrence that is not consistent with the simpler idea of spatially synchronised cycling.

I review the history of forest tent caterpillar, Malacosoma disstria (Hübner) (Lepidoptera: Lasiocampidae), occurrence from 1938 to 2001 throughout Canada, with emphasis on the insect’s impact on tree mortality. I show that forest tent caterpillar routinely kills a portion of its host tree population during outbreaks. Although the proportion killed is typically small, there are some unusual conditions during which the foliage grazer can precipitate large-scale host forest declines. These decline episodes are the result of a spatially complex pattern of outbreak spread whereby successive cycles occur asynchronously enough that there is a zone of overlap where the two cycles occur in rapid succession, leading to three to six years of defoliation, triggering a nonlinear mortality response that endures through time. One of these “cycles” is typically amplified locally to an intensity that is anomalously high and nonrecurring. Defoliation events that are periodic in aggregate may thus give rise to patterns of insect-caused forest decline that are episodic. These decline events have been shifting northwards over time and have been growing in extent. The dynamics of outbreak occurrence appears to be a complex result of interacting top–down and bottom–up forces, making it challenging to predict in advance whether or not any given outbreak will exceed the threshold required to precipitate large-scale mortality.

Eriocampa ovata (Linnaeus) (Hymenoptera: Tenthredinidae), commonly known as woolly alder sawfly, is an introduced species to North America. Its larvae have six or more prolegs, a brown spot on the head’s vertex, and are woolly in appearance due to a wax secretion from epidermal glands. The author was contacted about six recently planted alder trees in Winnipeg and Victoria Beach, Manitoba, Canada. The trees were determined to be Alnus hirsuta ‘Harbin’ (Betulaceae) (Prairie HorizonTM Manchurian alder), a tree species that has recently gained popularity in Manitoban urban forestry. The defoliation was determined to be caused by larvae of E. ovata. This is the first published record of E. ovata in Manitoba and the first published record of E. ovata on A. hirsuta. This detection should inform pest inventories for E. ovata in Manitoba and provide the basis for a critical examination of biosecurity measures for A. hirsuta.

The functional response of parasitoids is a main component of models that describe host–parasitoid interactions. When the functional response assumed in a model (e.g., a population model) is inaccurate, predictions by the model based on the functional response also become unreliable. This study reports that conventional functional response models may commonly fail to capture the actual functional response of parasitoids and discuss its implications. To assist the discussion, an experiment was conducted to describe interactions between the pupal parasitoid Dirhinus giffardii (Hymenoptera: Chalcididae) and its host Bactrocera dorsalis (Diptera: Tephritidae) in the laboratory. Results showed that the parasitoids typically interacted with all hosts in the environment but parasitised a small fraction of them (e.g., most encountered hosts were rejected), which deviates from the assumption of mechanistic functional response models. An increasing number of published studies on functional response also suggest (although circumstantially) the rejection of unparasitised hosts is common, suggesting that this behaviour is widespread among parasitoid species. By using the experimental results, the study discusses why existing hypotheses are insufficient for the observed behaviour and the implications of this behaviour within the realm of theories surrounding host–parasitoid interactions.

We examine the fossil weaver ants (Formicidae, Formicine, Oecophyllini) of the early Eocene Okanagan Highlands fossil localities of British Columbia, Canada and Washington, United States of America, naming Eoecophylla quilchenensis n. gen. et sp. from Quilchena (British Columbia), formally transferring Camponotites kraussei Dlussky and Rasnitsyn (Republic, Washington) to the genus Oecophylla Smith, F., and describing but not naming a worker (McAbee, British Columbia), treated as Oecophyllini sp. A. These are the oldest known Oecophyllini (Oecophylla + Eoecophylla) and Oecophylla. Forewing vein stubs of E. quilchenensis and its well-developed hind wing vein M are plesiomorphies; this M is unique within the subfamily, suggesting Oecophyllini is sister to other Formicine. The head shape of O. kraussei n. comb. indicates a close relationship to Oecophylla longiceps Dlussky from Eocene Messel, Germany. The ant Titanomyrma Archibald et al. is also known from the Okanagan Highlands and Messel, consistent with Late Cretaceous/early Paleogene intercontinental dispersal. We discuss possible host plants and trophobionts of these ants. Although Okanagan Highlands localities were cooler than the Paleotropical range of modern Oecophylla, their presence there might be explained by mild winters without significant frost.

The blow flies (Diptera: Calliphoridae) include many species that are important as nuisance flies, disease transmitters, and pollinators and are also very important in forensic entomology. Understanding the presence, phenology, and abundance of species in a given area is important in analysing a forensic case and is also valuable in developing baseline databases for comparison over time. Little work on Calliphoridae has been conducted in Manitoba, Canada. Baited traps were deployed at eight sites around the Winnipeg area throughout the insect season in 1978, 1979, and 1980. Five species, Cynomya cadaverina (Robineau-Desvoidy), Protophormia terraenovae (Robineau-Desvoidy), Phormia regina (Meigen), Lucilia illustris (Meigen), and L. sericata (Meigen), were regularly collected, with Calliphora spp. Robineau-Desvoidy collected much less frequently. The same species were collected consistently over the years of trapping, although abundance varied greatly even at the same sites.

Dermacentor variabilis and Dermacentor andersoni (Acari: Ixodidae) parasitise the same range of hosts in western Canada and have largely allopatric ranges except for a zone of sympatry in southern Saskatchewan, where these species experience the same environmental conditions. We report herein the discovery of differences in the behaviour of D. variabilis and D. andersoni larvae after they emerge from eggs. A behavioural diapause observed in D. variabilis larvae was not detected in D. andersoni larvae that were exposed to the same environmental conditions. As unfed D. variabilis larvae can successfully overwinter, their behavioural diapause represents an adaptive strategy to synchronise their questing activity and life cycle stage to maximise the chance of larvae encountering a suitable rodent host at the onset of spring. Such strategy will be of a significant benefit for colonising individuals at the northern edge of the distributional range of D. variabilis.

We explored ecological aspects of the early establishment of the association between the Japanese beetle, Popillia japonica (Newman) (Coleoptera: Scarabaeidae), and the adult tachinid parasitoid, Istocheta aldrichi (Mesnil) (Diptera: Tachinidae), in the province of Québec, Canada. The Japanese beetle started its invasion in the late 1930s, whereas I. aldrichi was detected only in 2009. It is assumed that I. aldrichi spread in the province from its introduced range in the northeastern United States of America. Throughout the summer, we used baited traps in eight localities of southern Québec (2018–2019) and in 13 raspberry (Rubus idaeus) fields (2022) localised along a latitudinal gradient to describe the distribution and seasonal occurrence of both species and the parasitism rates of I. aldrichi. We also mapped observational data from the online platform iNaturalist to further describe the current distribution of both the host and its parasitoid. Results indicate that I. aldrichi is well spread in southern Québec and along the St. Lawrence River in most areas where the Japanese beetle is present. Parasitism mostly occurs from late June to mid-July, before the peak of Japanese beetle populations, and levels of total seasonal parasitism range from 3.9 to 27.3% across sampled sites. Together, trap captures and data from iNaturalist provide evidence that I. aldrichi is now established in most areas of the province of Québec where the Japanese beetle is present.

Thrips (Thysanoptera: Thripidae) communities in agroecosystems are poorly known, particularly in Québec, Canada, where thrips can cause damage in strawberry crops. The phenology of anthophagous thrips and their use of cultivated and wildflower resources were monitored in strawberry agroecosystems, encompassing strawberry (Rosaceae) fields and adjacent uncultivated margins, on Orléans Island, Québec, Canada. A community comprised of 11 thrips species was described, dominated during the whole season by pest species Frankliniella tritici and F. intonsa, which is a first mention in Eastern Canada. Surprisingly, the major strawberry pest F. occidentalis was absent in our samples. Thrips species richness and abundance on wildflowers varied, with few flowering plant species supporting a majority of the community. Sampling sites and local wildflower presence influenced the thrips species assemblage observed on strawberry crops. Such a high thrips diversity was unexpected in this agroecosystem. The identified associations between pest thrips and wildflower species will be useful to develop better control programmes in strawberry crops.

Thirty-one species of Cinara Curtis (Hemiptera: Aphididae) are recorded from Japan, including five that are undescribed. We here formally describe one of the five, Cinara stigmatica sp. nov., from viviparous apterous females on two species of Abies Miller (Pinaceae). Morphological and molecular diagnoses are provided. Specimen data are simultaneously published in an open-access machine-readable format.

The forest tent caterpillar, Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae), is an irruptive forest pest found throughout North America. Widespread species such as M. disstria are exposed to historical and contemporary processes that are not uniform and can generate regionally distinct genomic variation. Previous analyses used a short mitochondrial fragment to infer broad-scale phylogeographic patterns in M. disstria, whereas nuclear markers have been previously applied only in a smaller geographic region. In this study, we quantified M. disstria population variation with genome-wide single nucleotide polymorphisms and cytochrome c oxidase from mitochondrial DNA. Using highly variable genome-wide markers, we resolved clear genomic differences among populations of M. disstria east of the Rocky Mountains that were not detected using mitochondrial variation alone. We also did not detect host-associated divergence in either our genomic or mitochondrial data. Our results highlight the utility of genome-wide markers to resolve intraspecific population structure within a widespread species and support the need for further biogeographic sampling of this forest insect pest.

Forensic entomology is an important component of criminal investigations, providing information surrounding a death using region-specific data on the local necrophagous community. To understand the community within the Metro Vancouver region of British Columbia, Canada, a field study monitored the abundance and diversity of necrophagous Calliphoridae (Diptera) over a nine-month period in distinct terrestrial environments. Baited bottle traps (n = 9) were deployed weekly for 12-hour intervals in three different environments. Species, sex, and gravidity of collected specimens were determined. Bivariate analyses revealed significant relationships between species, geographic location, and month of collection, suggesting that Calliphoridae species composition is influenced by habitat type and seasonal shifts in temperature. Sex ratios and reproductive ranges of Calliphoridae differed among the habitats sampled.

For solitary bees, nesting substrate availability may limit population growth. Here, we investigate the nesting of a locally abundant bee Osmia conjuncta Cresson (Hymenoptera: Megachilidae) in empty shells of exotic snails, Cepaea spp. Held (Stylommatophora: Helicidae), in Hamilton, Ontario, Canada. A literature review determined that O. conjuncta was sparsely distributed throughout its range, with a low relative abundance except for the Niagara Region of Ontario, Canada, three sites in Maryland, United States of America, and the focal study area in Hamilton, Ontario. The Hamilton field survey of five grassland bee communities found O. conjuncta to be the most abundant bee species. The average relative abundance was 18.7%, peaking at 87% on one spring day. A survey of 1088 empty snail shells was done at the site with the highest O. conjuncta abundance. It revealed an average of 10.87 empty shells per square metre with cocoons in 9.8% of the shells, averaging 1.6 cocoons per nest. The relation between shell traits and cocoon presence indicated that O. conjuncta preferred nesting in shells with intermediate size and colour and avoided shells near shrubs. The presence of Cepaea snails increased O. conjuncta populations with potential consequences to the local bee assemblage.

We evaluated the diversity and spatiotemporal emergence patterns of parasitoid wasp species in the genus Eurytoma Illiger (Hymenoptera: Eurytomidae) associated with leaf galls induced by Diplolepis variabilis Bassett (Hymenoptera: Cynipidae) throughout the Okanagan Valley, British Columbia, Canada. We collected D. variabilis galls throughout the region, recorded adult Eurytoma emergence times, extracted mitochondria DNA from a subset of the emergents, and used cytochrome c oxidase 1 and cytochrome b amplificons to assign sampled individuals to species. We also assayed for the bacterial endosymbiont Wolbachia to evaluate the incidence of thelytoky in Eurytoma. Eurytoma showed an extended emergence period and a significant right skew in male emergence. We recorded six Eurytoma species, one of which appears to be previously undescribed. The greatest diversity of Eurytoma species occurs in the north of the sampled area. Five of the six species showed Wolbachia infection in at least some individuals, and the most abundant and widespread species, Eurytoma imminuta Bugbee, showed high Wolbachia infection levels and an all-female population, which strongly indicates endosymbiont-induced thelytoky. Our results demonstrate that gall communities are locally variable, and we suggest that future studies be undertaken to quantify variation in community composition at more local scales than has been past practice.

Intermittent streams that periodically cease surface flow have long been understudied in ecology and underrepresented in conservation policy. However, they currently account for 30–50% of the global river network, and that number is rising due to anthropogenic water extraction, land-use change, and climate change. We explored the Coleoptera biodiversity of the south Pacific coast region of British Columbia, Canada, using pitfall traps at perennial and naturally intermittent stream reaches, in shoreline, dry streambed, and riparian habitats, in both flowing (spring and early summer) and nonflowing (late summer) phases. We found that habitats around perennial reaches had significantly greater abundance of Coleoptera individuals than did those around intermittent reaches. However, neither habitat type nor flow regime was a significant predictor of taxon richness, and intermittent stream sites featured unique taxa that were not found near perennial streams. This aligns with recent results from other taxonomic groups; that is, finding that intermittent ecosystems can host high taxonomic diversity of Coleoptera, on par with or even greater than that of perennial streams. Because intermittent streams will likely become more prevalent within the global river network, a better understanding of how different species use these habitats is needed to inform appropriate biodiversity conservation efforts and flow management.