Quebec is Canada’s leading producer of lowbush blueberries (Ericaceae), a crop reliant on honey bees (Hymenoptera: Apidae) for pollination. Intensive pollination services may adversely affect bee health. Few studies have examined the impact of increasing colony density and its carryover effects. This study compares control colonies used for honey production with colonies placed at two pollination densities (2.5 and 5 colonies/ha) in Saguenay–Lac-Saint-Jean over two years (2022–2023). Colonies were assessed at the start and end of pollination and one month later. We evaluated colony strength, Varroa destructor (Mesostigmata: Varroidae) infestation, pathogen loads (including Vairimorpha spp. (Nosematidae), and viruses such as deformed wing viruses A and B (Iflaviridae) and acute bee paralysis virus, Israeli acute paralysis virus, Kashmir bee virus, chronic bee paralysis virus, and black queen cell virus (all Dicistroviridae), and pesticide residues. Pollination was associated with reduced colony strength gain, higher proportions of colonies infested with Varroa, and increased deformed wing virus B loads. Colony strength was most affected by increased density in the carryover assessment. No pesticide levels exceeded bee toxicity thresholds in nectar and bee bread. This is the first study to evaluate colony density effects on honey bee health in lowbush blueberry systems.

Critical examination of artistic embellishment on maps is useful for understanding values, fears, and political leanings of the past. The 1750 “Porcupine Map” by Moses Harris, published in The Gentleman’s Magazine (London, United Kingdom), depicted Halifax Harbour to encourage British emigration to Nova Scotia. Compared to earlier regional maps, changes reflected in the Porcupine Map, such as removing depictions of Indigenous Mi’kmaq, suggest efforts to make the colony feel more familiar to British readers of the time. Although the titular porcupine illustration has received significant interest, the map also features three prominent insects labelled as “The White Admirable,” “The Orange Underwing Tyger,” and “The Musk Beetle.” These common names refer to species occurring in Britain but not in Nova Scotia. We posit that “The White Admirable” depicts the American white admiral, Limenitis arthemis Drury (Lepidoptera: Nymphalidae), and “The Orange Underwing Tyger” represents the St. Lawrence tiger moth, Arctia parthenos Harris (Lepidoptera: Erebidae). Although less detailed, “The Musk Beetle” illustration resembles the brown prionid, Orthosoma brunneum Forster (Coleoptera: Cerambycidae), a conspicuous long-horned beetle native to North America. Including these detailed depictions of insects but mislabelling them as European species may be due to human error, artistic licence, or an overlooked expression of imperialistic propaganda.

Red alder, Alnus rubra Bongard (Betulaceae), is a keystone hardwood tree species of great ecological importance in riparian, mixed, and recently disturbed forests in the Pacific Northwest of North America. The alder bark beetle, Alniphagus aspericollis (LeConte) (Coleoptera: Curculionidae: Scolytinae), is an insect that infests and kills red alder throughout its range. Recent observations in southwestern British Columbia, Canada, have indicated that widespread red alder mortality may be attributed to attacks by the alder bark beetle. The most studied defence compound in red alder is oregonin, a diarylheptanoid xyloside. Past studies have shown oregonin to generally inhibit lepidopteran herbivory, but no research has investigated its effects on subcortical insects, such as the alder bark beetle. We hypothesised that high oregonin content is related to resistance to alder bark beetle colonisation in red alder. In support of our hypothesis, we found that the phloem oregonin content of trees that were successfully colonised by the alder bark beetle was significantly lower than that of trees that were not attacked and those that resisted colonisation. These results suggest that oregonin may be a defence metabolite in red alder phloem, although further studies are needed to evaluate how oregonin could influence beetle colonisation success.

Hypena opulenta (Lepidoptera: Erebidae) has been introduced to control invasive swallow-worts (Apocynaceae) in North America. However, population densities remain too low to suppress weed populations. We examined winter cold and soil moisture as potential factors limiting H. opulenta population growth in Canada. We characterised cold-tolerance strategy, susceptibility to inoculative freezing (freezing initiated by external ice formation at higher subzero temperatures), and examined the effects of prolonged cold exposures on H. opulenta survival. Finally, we conducted a laboratory experiment to determine whether soil moisture content affects the cold hardiness of H. opulenta pupae. Hypena opulenta pupae are freeze-tolerant, but only 22% survived prolonged exposure to –15 °C for 15 hours. After 1-hour cold exposures, survival of pupae in which freezing was inoculated at high temperatures (25%) was lower than that of untreated pupae (62%). After 15-hour cold exposures, however, there was no difference in survival between inoculated and untreated pupae. Pupal mortality was not affected by cold-exposure duration or inoculative freezing in soil, but male pupae had higher survival than females. These results suggest that H. opulenta has the potential to continue to survive, grow, and eventually impact swallow-wort populations in Canada without being limited by winter conditions.

In herbivorous insects with seasonal host switching, females are exposed to seasonal environmental heterogeneity arising from variation in oviposition host plants and abiotic conditions such as temperature. However, few studies have examined plastic variation in egg size, shape, and number among generations associated with different host plants. Elasmostethus nubilus (Dallas) (Hemiptera: Acanthosomatidae) is a bivoltine herbivorous shield bug that switches host plants between generations. In our study population, overwintered females (first generation) use Fatsia japonica (Thunberg) Decaisne and Planchon (Araliaceae) for breeding, whereas newly emerged adults that developed on this host plant (second generation) migrate to and breed on Dendropanax trifidus (Thunberg) Makino ex Hara (Araliaceae). We found that females of the first generation laid fewer but larger and more elongated eggs than those of the second generation, despite no significant difference in female body size. No phenotypic trade-off between egg size and clutch size was detected in either generation. Within each generation, we found no evidence of a positive allometric relationship between egg size and egg shape, as would be expected under constraints such as limitations imposed by female anatomy. We discuss potential factors underlying the observed intergenerational variation in maternal resource allocation and egg shape.

The willow mason wasp, Symmorphus bifasciatus (Linnaeus) (Hymenoptera: Vespidae), is a Palearctic and Oriental species, which we verify as having been introduced to North America at least as early as 2010. Since then, it has become established across Canada, a fact which came to light through Bees@School, a community science initiative in which solitary bee nests were deployed across Canada from 2019 to 2023. Using DNA barcoding, with identifications subsequently confirmed by morphological identification of barcoded specimens, we detected S. bifasciatus 80 times throughout the sampling period.

Oak wilt is a serious disease of oaks, Quercus spp. (Fagaceae), caused by a fungal pathogen Bretziella fagacearum (Bretz) de Beer et al. (Ceratocystidaceae). This disease, first described in the United States of America in the 1940s, was recently discovered in southern Ontario, Canada. Spread of oak wilt in eastern Canada may pose a significant risk of oak mortality. Sap beetles (Coleoptera: Nitidulidae) play a crucial role in spreading the disease. However, little is known about the seasonal abundances of sap beetle species in Canada, and in Quebec in particular. Therefore, sap beetle collections were made from different environmental settings (referred broadly here as “habitat types”) in the Greater Québec City Area, Quebec, in 2021 and 2022. Results showed that sap beetle abundances differed by habitat type and season. Two vector species that we examined closely, Caplothorax sayi Parsons and Colopterus truncatus (Randall), were most active from May to July. Urban forests were key habitat reservoirs for these two species. Our findings suggest that cities should prioritise sap beetle surveillance in urban forests because early detection of oak wilt through vectoring insects will be crucial to stop the spread of the disease into eastern Canada.

Two new species of podapolipid mites (Trombidiformes: Heterostigmatina) are described from subelytral spaces of carabid beetle (Coleoptera: Carabidae) hosts from Alberta, Canada. Eutarsopolipus husbandi sp. nov., a member of the pterostichi species group, is parasitic on Pterostichus adstrictus Eschscholtz, 1823 and is closest to two European species, E. pterostichi Regenfuss, 1968 and E. vernalis Regenfuss, 1968. Eutarsopolipus paraplatyni sp. nov., a member of the biunguis species group, is parasitic on Platynus decentis (Say, 1823) and is closest to the North American species E. platyni Husband and Husband, 2002. We provide a table of diagnostic features of the enigmatic pterostichi group. These two new species bring the total number of Eutarsopolipus spp. known from Canada to seven and the total number of named species in the world to 103.

Quadrat sampling from May to September was used to estimate densities of overwintered adults, third-instar larvae, and late-summer new-generation adults in a population of Chlaenius cordicollis Kirby (Coleoptera: Carabidae) on a stony beach of Lake Winnipeg, Manitoba, Canada. Densities of eggs were estimated from densities of overwintered reproductive females and average female fecundity. Results were used to construct stage-specific life tables for 15 consecutive cohorts of C. cordicollis, with four density estimates and three intervening mortality estimates for each cohort. The key mortality factor was that between eggs and third-instar larvae – mortality that was positively correlated with rainfall. Mortality between third-instar larvae and fall adults was greatest when beach width was most variable – a symptom of wind-driven seiches. Overwintering mortality was positively correlated with the amount of rain falling on the snow drifts under which beetles overwinter and with rainfall and variability of beach width in early spring. Overwintering mortality was density-dependent. It is hypothesised that the mechanism of density dependence is prewinter competition for food, resulting in some beetles entering overwintering sites with inadequate metabolic reserves to survive until they can feed in the spring.

Gall-inducing insects must chew an exit tunnel from their larval chamber to the gall surface, and this process varies widely among lineages. One distinctive strategy involves excavating to the gall surface while leaving a thin epidermal membrane through which the insect later exits. This behaviour has been documented primarily in gall-inducing Diptera and has not previously been reported in Hymenoptera. Here, the first known instances of the behaviour in gall-inducing wasps (Hymenoptera: Cynipidae: Cynipini) are documented, and the term “windowing” is proposed. In the observed wasps, adults excavated emergence tunnels terminating beneath a light-permeable outer membrane and delayed final emergence. Unlike Dipterans, adult cynipids possess robust mandibles capable of chewing lignified tissue, suggesting windowing is unlikely to function solely as a mechanical aid to emergence. Instead, it is hypothesised that the retained membrane may allow adults to assess external environmental cues prior to emergence, potentially increasing fitness under variable conditions. Further experimental work is needed to test this hypothesis.

Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) is a global pest that causes severe damage to blueberries (Ericaceae). Current management strategies rely heavily on intensive insecticide use, which can adversely affect beneficial organisms and promote the evolution of insecticide resistance. The development of sustainable control methods against S. dorsalis requires basic information about its bioecology. This study investigates the effect of temperature on the development, survival, and reproduction of S. dorsalis when reared on blueberries. The results indicate that temperature significantly affects preimaginal developmental time and female S. dorsalis fecundity. The developmental time was longer at 18 °C (36.6 days) than at 30 °C (9.6 days). Temperature significantly affected longevity, with females living longer at 24 °C, with an average lifespan of 14.9 days, compared to 9.5 days at 30 °C. The highest daily oviposition rate was observed at 24 °C, averaging 2.8 eggs/day, whereas the lowest rate occurred at 18 °C, averaging 0.2 eggs/day. The lower developmental threshold was estimated to be 13.6 °C, and the thermal constant, 169.5 degree-days. The findings provide essential information on the development and reproduction of S. dorsalis, which could be useful for predicting field populations and implementing appropriate management strategies for this pest.

Increasing wheat (Poaceae) production to ensure global food security remains an important challenge, underscoring the significance of environmentally friendly approaches, including use of beneficial microorganisms. In laboratory and field experiments, we tested beneficial microorganism effects on the biological parameters of wheat and on wheat thrip, Haplothrips tritici (Thysanoptera: Phlaeothripidae). Plant growth–promoting rhizobacteria Pseudomonas fluorescens (Pseudomonadaceae) and Bacillus subtilis (Bacillaceae) were evaluated for their effectiveness both individually and in combination. Plant growth–promoting fungi Trichoderma harzianum (Hypocreaceae) and arbuscular mycorrhizae Glomus mosseae (Glomeraceae) were also assessed separately and in combination. In vitro inoculation with P. fluorescens strains enhanced wheat shoot and root growth. Among microbial biofertilisers, seed treatment with both P. fluorescens and B. subtilis led to various enhanced growth indices under field conditions. Plants treated as seed attained the highest number of grains per spike, root weight per plant, plant height, and chlorophyll content. The lowest populations of thrips per spike were realised with the application of arbuscular mycorrhizal fungi or P. fluorescens alone. Microorganism-based fertilisers can be employed as components of integrated pest management strategies to promote wheat performance and improve yield quality and quantity. This approach supports sustainable agriculture by reducing reliance on conventional insecticides.

Communities comprising multiple temperate tephritid flies infesting the same host fruit may provide insights into how species partition resources to avoid competitive exclusion. Using Euphranta canadensis (Loew) and Rhagoletis ribicola Doane (Diptera: Tephritidae) that share golden currant, Ribes aureum Pursh (Grossulariaceae), as a model, we hypothesised that adults and larvae of these flies temporally divide host fruit to coexist. Fruit loads, fruiting phenology, fly catches, and larval infestation levels were determined in central Washington state, United States of America, in 2023, 2024, and 2025. Adult E. canadensis abundance peaked in May when most currants were immature and that of R. ribicola peaked in June when most currants were mature. Only E. canadensis larvae emerged from fruit collected in May; both species emerged from fruit collected in June; and only R. ribicola emerged from fruit collected in July. In June, larval niche overlap was 0.543–0.996, but no larvae emerged from 94–99% of fruit collected, suggesting currants can be an unlimited resource. Our results suggest that temporal partitioning of fruit resources and low infestation rates may help mitigate interspecific competition between E. canadensis and R. ribicola, with implications for monitoring or management of tephritid pests that co-occur in fruit trees.

The Poweshiek skipperling, Oarisma poweshiek Parker, 1870 (Lepidoptera: Hesperiidae), is an endangered, univoltine grassland butterfly with extant populations in Michigan, United States and Manitoba, Canada. Larvae of this species are cryptic and have proven challenging to observe in situ. Features of Poweshiek skipperling life history, including the overwintering instar and larval degree-day requirements, have not yet been documented in Manitoba. In this study, we used macro photography to measure head capsule widths of more than 1000 Poweshiek skipperling larvae reared ex situ at Assiniboine Park Zoo in Winnipeg, Manitoba, Canada. Most larvae overwintered in the fourth instar and completed a total of six instars, but third and fifth instars also successfully overwintered. Two sixth instars failed to survive the winter. We produced pre-winter degree-day estimates for ex situ larvae and found significant differences in annual accumulations but no significant difference in overwintering instar between years. Our results address knowledge gaps related to Poweshiek skipperling biology that will benefit ongoing ex situ rearing efforts and in situ conservation actions. In addition, the noninvasive methods presented here would be ideal for studying the growth and development of other endangered insects.

Diverse strategies for overwintering are found among bark beetle (Coleoptera: Curculionidae: Scolytinae) species, yet costs and benefits of these strategies are seldom considered. The lifecycle of the alder bark beetle, Alniphagus aspericollis (LeConte), in red alder, Alnus rubra Bongard (Betulaceae), is univoltine and comprises two cohorts; the first overwinters as adults, often inside branch nodes, and the second overwinters as mature larvae in the main stems (i.e., boles) of trees. We investigated prevalence of the entomopathogen Beauveria Vuillemin (Ascomycota: Cordycipitaceae) and adult body size in both beetle cohorts to determine whether fitness trade-offs may exist for these alternative overwintering strategies. Adult beetles were collected from sites across southwestern British Columbia and evaluated for presence of Beauveria on the exoskeleton (via culturing) and body size. Bole-overwintering beetles were eight times more likely than branch-overwintering beetles to be associated with Beauveria. Branch-overwintering beetles, however, were approximately 11% smaller than bole-overwintering beetles, and dissections revealed that these beetles may use maturation feeding to offset some costs of dispersal and reduced body size associated with overwintering. We speculate that potential fitness costs associated with dispersal and reduced body size in the branch-overwintering cohort may be outweighed by benefits of reduced exposure to Beauveria.

The intentional importation and release of nonnative biological control agents (BCAs) to manage arthropod pests is typically regulated at the national level. However, redistribution of arthropod BCAs within national borders may be considered to control the target pest in regions where the BCA is not currently present. Science-based guidelines for subnational redistributions of BCAs that are already present in Canada but have not been approved for importation and release by regulators (e.g., adventive species) are currently lacking. This is increasingly relevant given recent detections of nonnative, adventive BCAs that have become established without the safety assessment and regulatory oversight associated with intentional introductions. In this paper, we outline considerations and best practices for subnational redistributions of arthropod BCAs targeting arthropod pests, focusing on the Canadian context. We present case studies of previous and ongoing redistributions of BCAs in Canada and evaluate examples of BCA species that could be redistributed in the future. Finally, we provide recommendations for best practices for BCA redistributions, including documenting the rationale for redistributions, having the rationale subjected to scientific peer review, and engaging stakeholders to support science-based decision-making.

Social parasitism is a life history strategy in which individuals take advantage of existing parental care behaviours to rear their offspring. In yellowjackets, social parasitism remains comparatively understudied, particularly with respect to host defensive behaviour. Here, we report defensive behaviour and serotonin immunoreactivity associated with the social parasite yellowjacket, Vespula flavopilosa Jacobson (Hymenoptera: Vespidae), in colonies of two free-living yellowjacket species, V. pensylvanica Saussure and V. maculifrons du Buysson. Field disturbance assays measuring latency, response duration, and total strikes suggested differences in defensive behaviour between the two host species, with V. maculifrons responding to disturbance more quickly than V. pensylvanica. In addition, behavioural findings also suggested that the relationship between the proportion of V. flavopilosa in each sampling period and defensive-response duration differed between the two host species. Immunohistochemistry experiments revealed associations between defensive-response measures and serotonin immunoreactivity in the optic lobe medulla and mushroom body calycal lip. These findings identify behavioural and serotonergic correlates of yellowjacket social parasitism and highlight this system as a target for future study.

While many studies on ectotherm thermal tolerance consider temperature exposure, the frequency of temperature exposures is an overlooked driver of survival and fitness that may influence species ranges. We use a physiologically informed species distribution model to evaluate the influence of temperature threshold crossings on defoliation by the spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae), a Canadian boreal forest pest. We combined maps of defoliation between 2006 and 2016 in Quebec with climate, forest, and temperature fluctuation predictors which quantify the number of temperature threshold crossings in a month to train a species distribution model. Our model evaluated how predictors influence spruce budworm defoliation and compared these results to a model trained without temperature fluctuations. Additionally, we investigated the effect of temperature fluctuations on predicted defoliation under 2041–2070 climate change conditions using the models trained with and without temperature fluctuations. We found that the inclusion of temperature fluctuation predictors improved model performance, and these predictors ranked highly in importance relative to other categories. The model trained with temperature fluctuation predictors also predicted vastly different future defoliation patterns across eastern Canada than the model trained without them. Our study reveals the importance of temperature fluctuations on spruce budworm defoliation and demonstrates the influence of physiologically informed predictors in species distribution models.