Local temperatures can shape the ability of introduced species to flourish and disrupt novel environments. The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive beetle that threatens ash trees in North America and Europe. To assess the role of temperature on EAB reproduction, we reared groups of adult beetles at one of four temperatures (12 degrees C, 15 degrees C, 18 degrees C, and 21 degrees C) and measured reproductive success (laying fertilized eggs and egg hatching). There was no effect of rearing temperature on EAB female lifespans, but no eggs laid at 15 degrees C or 18 degrees C hatched, suggesting these temperatures disrupt the reproductive process of EAB. Females reared at 21 degrees C, however, consistently laid eggs that hatched. We then used these results to assess the likelihood of reproductive success over a recent 10-year period in eight cities in Canada that host EAB. All locations experienced temperatures of >= 21 degrees C, but the number of hours and the number of days above this critical temperature were highly variable. There were ample opportunities in all locations for EAB to reproduce, but EAB in cooler cities would experience thermal limitations, thus slowing the spread of EAB populations.

Local hydrological conditions play a major role in shaping insect assemblages and can drive geographical and localized variation in the success of biological control agents. Archanara neurica and Lenisa geminipuncta, two insects for Phragmites australis spp. australis (introduced Phragmites), are being released in Canada, but it is unknown whether agent releases will work in sites with standing water. We addressed this knowledge gap by (1) assessing the submergence tolerance of A. neurica and L. geminipuncta eggs in laboratory conditions, (2) comparing predation of A. neurica eggs in wet and dry habitats, and (3) examining the effects of hydrological conditions on the success of A. neurica releases and subsequent population persistence.Submersion of A. neurica and L. geminipuncta eggs for up to six weeks in the laboratory had no negative effect on egg viability. In the field, egg mortality due to predation between July 2024 and May 2025 was not affected by hydrological conditions. Finally, releases of A. neurica eggs and larvae performed equally well in wet and dry locations, and both significantly affected Phragmites stand characteristics (stem density or panicle formation) within release plots.The success of A. neurica releases in flooded environments suggests that the moths can be used in wet release sites that might previously have been avoided. The ability to release the moths over standing water will be crucial for the integration of biological control with conventional management tools, the use of which can be restricted in flooded environments.

The timing of spring activity and oviposition in the knotweed psyllid, Aphalara itadori Shinji (Hemiptera: Psyllidae), will affect the number of generations that this biological control agent can complete across its introduced range and its impact on invasive knotweed. We conducted a controlled overwintering experiment in Ontario, Canada, to observe patterns of A. itadori activity and oviposition in spring and to explore sources of spring mortality. Aphalara itadori were observed to be active in very early spring, with the first observation of a psyllid on a sentinel leaf occurring on 23 March 2021. The first viable eggs were laid between 18 and 20 April 2021, when mean maximum daily temperatures were ~14 °C and day length was 13.36 h. Psyllid activity/survival throughout the spring was not affected positively or negatively by access to foliage. Our results suggest that, in Canada, the timing of the first spring generations of A. itadori will likely be dictated by the phenology of the host plant rather than the biology of the insect. The results also suggest that spring mortality in A. itadori, from starvation or abiotic factors, is low even when knotweed emergence is late.

Several Monochamus species (Coleoptera: Cerambycidae) use monochamol as an aggregation-sex pheromone, raising questions about how they maintain reproductive isolation. Herbivorous insects use host plant semiochemicals as cues for mate location and, with or without habitat cues, these could confer reproductive isolation among sympatric Monochamus spp. To test this hypothesis, host and habitat preferences in mate location were examined for sympatric populations of Monochamus maculosus, Monochamus notatus, and Monochamus scutellatus in the Algoma District, Ontario, Canada. Field experiments were performed to investigate whether differences in host preference, vertical distribution across the forest canopy, spatial distribution within down and standing dead trees, or any combination of these factors could minimise cross-attraction to monochamol. Results showed that more M. maculosus were attracted to monochamol combined with jack pine foliage than with balsam fir or white spruce, whereas no differences in host attractivity were observed for the other species. Vertical abundance of M. maculosus and M. scutellatus was similar across forests. Spatial distribution provided limited evidence for species segregation within hosts. No evidence was found that host or habitat preferences contribute to reproductive isolation in M. maculosus, M. notatus, or M. scutellatus, suggesting that vertical distribution could be driven by resource availability.

Pest management strategies for invasive species like the emerald ash borer (EAB) must combine chemical control with biological control agents to protect vulnerable hosts. When used in tandem with biological control agents, however, systemic insecticides may impact the fitness of biological control agents, thus reducing their effectiveness. Systemic insecticides are used for EAB management in urban forests across North America, while classical biocontrol with introduced natural enemies has been an important tactic for managing EAB in natural forests in North America. We tested the non-target effects of azadirachtin on Tetrastichus planipennisi Yang, a larval parasitoid of EAB introduced to North America. A novel bioassay protocol was developed whereby EAB larvae were initially reared on host material in the laboratory and then temporarily transferred to an artificial EAB diet containing azadirachtin followed by exposure to parasitism by T. planipennisi. Exposure to azadirachtin at concentrations causing 30% and 50% mortality in EAB larvae reduced EAB larval parasitism by T. planipennisi. Exposure to azadirachtin also reduced T. planipennisi’s sex ratio, adult emergence, female body size, potential fecundity, and adult longevity. These results suggest there are negative interactions between systemic insecticides and EAB biological control agents, which present challenges for the integration of tactics for long-term EAB management.

Detection and monitoring of biological control agents are critical for evaluating their establishment and spread yet remain challenging when species are cryptic, and densities are low. We assessed whether environmental DNA (eDNA) metabarcoding of stem residues could be used to detect and distinguish the stem-boring noctuid moths Archanara neurica and Lenisa geminipuncta, biological control agents of introduced Phragmites australis released in Ontario, Canada. Using 16S rDNA metabarcoding supplemented with newly generated reference sequences, we analyzed stem residue samples spanning a gradient of quality, including laboratory culture stems (in which agent larvae were present at the time of sampling), confirmed Canadian release sites, and degraded stems from unmanaged Phragmites stands in western New York, USA. Target species were consistently detected in laboratory samples, where they comprised 76.7-100% (L. geminipuncta) and 79.2-100% (A. neurica) of Lepidoptera reads. At Canadian release sites, A. neurica was detected in 5 of 11 samples and L. geminipuncta in all 10 samples, with relative read abundances ranging from trace levels to > 90%. Among 27 damaged stems collected in the United States, A. neurica and L. geminipuncta DNA was detected in three samples at very low abundances (0.003-0.12% of total reads), representing the first molecular evidence consistent with trans-border dispersal of these agents. Although detections were rare and do not confirm population establishment, results demonstrate that stem-residue eDNA metabarcoding provides a sensitive, non-invasive tool for early detection and post-release monitoring of biological control agents for invasive plants.

Abstract Forest canopies are vertically stratified habitats in which microclimate and host tissue quality vary with height. Scale insects (Hemiptera: Coccoidea) are ecologically important components of temperate forest canopies, producing honeydew exploited by bees, wasps and lepidopterans. The spatial distribution of tree scale insects thus has direct consequences for the availability of these resources but has not been described in North American hardwood forests. We quantified the abundance of three scale insect species and unidentified crawlers across upper‐, middle‐ and lower‐canopy strata of 33 sugar maple ( Acer saccharum Marsh.) trees in south‐central Ontario. We tested whether canopy position, tree size and year‐over‐year growth predicted scale abundance using per‐species negative binomial generalized linear mixed‐effects models (GLMMs). Scale insect communities were strongly vertically stratified, with all taxa reaching highest densities in the upper canopy. Species differed in their association with internode age: Lepidosaphes ulmi (L.) and crawlers peaked on the current year's leader, while Parthenolecanium corni (Bouché) peaked on the prior year's internode, particularly in large‐diameter trees. Tree size had no significant main effect for any taxon, though species‐specific patterns emerged within canopy strata. Shoot elongation was positively associated with subsequent scale abundance across multiple canopy positions and growth stages, while radial growth was negatively associated with abundance in the upper and mid canopy. After controlling for shared habitat use, Phenacoccus acericola King, Parthenolecanium and crawlers showed positive co‐variation at the branch scale; the crawler pool was most closely associated with Parthenolecanium . Within‐tree habitat heterogeneity, rather than tree‐level traits, drives the spatial structure of scale insect communities, with implications for the distribution of honeydew resources supporting canopy‐dependent arthropods.

Two biological control agents, Archanara neurica (Hübner) and Lenisa geminipuncta (Haworth) (Lepidoptera: Noctuidae), are being released in Canada for the control of invasive common reed, Phragmites australis australis (Cav.) Trin. Ex Steud (hereafter Phragmites). The release of larvae implanted in cut Phragmites stems is the most reliable way to establish agents at new sites, but the number of larvae that can be used for releases is limited by the short period of time over which egg hatch occurs. We conducted a cold storage experiment to assess whether the timing of egg hatch can be manipulated without affecting hatch success. Additionally, we conducted visual assessments of developing eggs to determine whether hatch timing can be predicted based on early signs of development. Eggs hatched indoors had lower hatch rates than eggs hatched in outdoor conditions. For A. neurica and L. geminipuncta, eggs could be held in cold storage for 11 and 8 weeks, respectively, without affecting hatch rates. Eggs of both species began hatching 4–7 days after the appearance of visible signs of larval development. Manipulating the timing of hatch in A. neurica and L. geminipuncta will increase the number of larval releases that can be conducted during the spring and allow the timing of releases to be optimized.

Soil invertebrates contribute to critical ecosystem processes in tropical regions, being highly diverse yet poorly studied. The addition of pyrolyzed biomass (biochar) to tropical soils can increase forest productivity by enhancing the availability of P and micronutrients, but effects on the invertebrate community have received little attention. Here, we present a 3-year study of litter invertebrates captured in pitfall traps in secondary forests experimentally enriched with non-timber forest product (NTFP) species and amended with kiln and traditional mound biochars at 10 t ha−1 in the Ecuadorian Amazon in a poorer alluvial sandy soil, and a colluvial soil with higher nutrient content. Soil conditions and seasonality were the main determinants of soil invertebrate community structure in multivariate analyses; however, biochar treatment effects were also detectable. Predators (ants and spiders) and microbivores (especially Poduromorpha) were the dominant functional groups in the study, with predators increasing over the collection seasons and microbivores decreasing. Microbivores showed reduced abundance at high Al availability, which was reduced by biochar addition. In contrast, predators showed increased abundance with increasing soil Al, but this pattern was only pronounced in the poorer alluvial soil and mixed NTFP treatment. In the colluvial soil, with higher nutrient content, parasitoid wasps increased in abundance with biochar additions relative to controls, while isopods showed a positive response to kiln-made biochar in the mixed NTFP treatment only. The findings indicate responses of soil invertebrates, in particular Poduromorpha, ants, and parasitoid wasps, to biochar amendments, but with patterns that vary over time and that are dependent on the specific biochar used as well as the soil type.

Herbivorous insects can have their reproductive potential influenced by the quality and species of host plants they feed upon. The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive pest of ash trees (Fraxinus spp.) within its introduced range. As adults, EAB must feed upon foliage to sexually mature. We compared the influence of 4 North American ash species on EAB via foliage feeding to assess impacts on female lifespan and reproductive metrics. We fed 136 female EAB, 34 in each foliage group, either black, green, tropical, or white ash throughout their adult life. We performed daily inspections for adult mortality, oviposition, and egg hatching. We found that the mean female lifespan, fertility rate, and mean egg development time were not affected by the ash species. Potential and realized fecundity each increased with summed female group lifespan (days), but this rate differed among ash species. Consequently, there was a statistically significant interaction effect of the summed female group lifespan and the host foliage. Green ash-fed EAB laid (2.94 ± 0.86 eggs/female days) and hatched (1.67 ± 0.59 eggs/female days) the most eggs, more than double the rates of EAB feeding on black (1.39 ± 0.48 laid and 0.75 ± 0.30 hatched eggs/female days) and white (1.08 ± 0.35 laid and 0.65 ± 0.22 hatched eggs/female days) ash. Adults feeding on green ash resulted in the greatest EAB fecundity suggesting that the presence of green ash may promote population growth and provide a pathway to overwhelm other ash species nearby.

An important component of post-release monitoring of biological control of invasive plants is the tracking of species interactions. During post-release monitoring following the initial releases of the weevil Ceutorhynchus scrobicollis Nerenscheimer and Wagner (Coleoptera: Curculionidae) on garlic mustard, Alliaria petiolata (Marschall von Bieberstein) Cavara and Grande (Brassicaceae), in Ontario, Canada, we identified the presence of larvae of the tumbling flower beetle, Mordellina ancilla Leconte (Coleoptera: Mordellidae), in garlic mustard stems. This study documents the life history of M. ancilla on garlic mustard to assess for potential interactions between M. ancilla and C. scrobicollis as a biological control agent. Garlic mustard stems were sampled at eight sites across southern Ontario and throughout the course of one year to record the prevalence of this association and to observe its life cycle on the plant. We found M. ancilla to be a widespread stem-borer of late second–year and dead garlic mustard plants across sampling locations. This is the first host record for M. ancilla on garlic mustard. The observed life cycle of M. ancilla indicates that it is unlikely to negatively impact the growth and reproduction of garlic mustard and that it is unlikely to affect the use of C. scrobicollis as a biological control agent.

Facultative diapause is a life history trait that allows insects to undergo continuous development when conditions are favorable or to enter diapause when they are not. Insect voltinism can have an impact on the success of a weed-biological control agent because additional generations can increase agent population growth and reduce late-season recovery in the target weed. The most common factors that cue diapause are photoperiod and temperature; however, the role of nutrition is increasingly being recognized. We conducted a laboratory experiment to examine the effects of photoperiod and foliage age on diapause induction, pupal weight, and pupal development time in Hypena opulenta (Christoph) (Lepidoptera: Erebidae), a biological control agent for invasive swallow-worts in North America. A factorial experimental design was employed whereby H. opulenta was reared at long (16:8 h light:dark) and short (12:12 h) photoperiods on young and old swallow-wort foliage (Vincetoxicum rossicum Kleopow) Barbar. (Apocynaceae). Photoperiod was the only factor that affected diapause induction in H. opulenta. While foliage age did not affect diapause induction, it did affect pupal weight and pupal development time, with older foliage resulting in lower pupal weight and extended pupal phase. In field conditions, these impacts could affect pupal mortality through reduced winter preparedness and increased exposure to predators. These results support H. opulenta voltinism models based on photoperiods and indicate that the tendency of captive-reared H. opulenta to enter diapause after 2 or 3 generations, even in the absence of short photoperiods, is not a result of changing foliage age.

Effective monitoring and surveillance of insect populations is critical for mitigating the threats they pose to ecosystems and economies. Flight intercept traps, including Lindgren funnel traps and cross-vane panel traps, are widely used in surveillance and monitoring programs for forest beetles. Their performance varies among species and the mechanisms underlying their function remain poorly understood. Previous research on trap design effects has predominantly relied on end-point assays, which fail to capture the behavioral processes driving trap performance and often result in oversimplified or teleological explanations, thereby limiting improvements in trap design. We developed and applied a simple 3-step model of trap function to understand the effects of trap design: (i) approach, where insects initiate directed movement toward the trap; (ii) capture, where contact with the trap results in either capture or escape; and (iii) retention, where captured insects remain in the trap or escape. Using observational experiments in the field, we investigated the behavioral responses of Monochamus spp. (Coleoptera: Cerambycidae) to intercept trap designs and collection cup treatments. Observation of beetle approaches to intercept traps revealed that a higher proportion of beetles progressed from 1 m to trap contact with panel traps compared to funnel traps, while escape rates from both wet and dry collection cup treatments were negligible. These findings highlight the importance of behavioral observations in improving our understanding of trap function and identifying features that enhance performance. By providing a mechanistic framework for insect-trap interactions, this work supports the development of more effective tools for monitoring insects.

Flight intercept traps are important tools for the monitoring and surveillance of forest Coleoptera. Although collection cup effects on the abundance of target taxa are well-documented, these effects remain poorly understood. Here, we investigated the comparative efficacy of three wet (saturated saltwater, propylene glycol, and soapy water) and one dry (dichlorvos strip) collection cup treatments on the capture of forest insects. We observed significant differences in capture rates across treatments, with wet cups generally resulting in higher captures of phytophagous and predatory taxa. Dry cups captured the largest quantities of carrion-associated taxa. These findings challenge the prevailing hypothesis of insect escape from dry collection cups and suggest that olfactory stimuli associated with collection cups are important in mediating trap performance. Despite these insights, the specific mechanisms driving these preferences remain unknown and should be the focus of future research.

The recognition of cerambycids as frequent and damaging invaders led to an increase in the interest in the chemical ecology of the group with the identification of pheromones and pheromone-like attractants for well over 100 species. Pheromone components of the Cerambycidae are often phylogenetically conserved, with a single compound serving as a pheromone component for several related species. In the subfamily Lamiinae, the compound 2-(undecyloxy)ethanol (monochamol) has been identified as an aggregation-sex pheromone for several species of the genus Monochamus. In other species, including Monochamus maculosus Haldeman, field trials have demonstrated that monochamol is a pheromone attractant, but at that point it was still unknown as to whether it was a pheromone for this species. Here we report the identification, and laboratory and field trials of a pheromone component produced by adult male M. maculosus. Chemical analyses of headspace volatile collections sampled from field collected beetles of both sexes revealed the presence of one male-specific compound that was identified as 2-(undecyloxy)ethanol. Electroantennography analyses showed that monochamol elicited responses from the antennae of female beetles. Traps baited with monochamol in the field captured M. maculosus adults of both sexes corroborating the identification of monochamol as the sex-aggregation pheromone of this species. The attractivity of monochamol to adult M. maculosus in our field trapping experiment was synergized by the addition of the host volatile α-pinene.

Field releases of the stem-boring moths Archanara neurica and Lenisa geminipuncta (Lepidoptera: Noctuidae) as classical biological control agents for introduced Phragmites australis australis (Cav.) Trin. ex Steud. began in Canada during 2019. Since then, we have developed and tested release methods for eggs and larvae of both agents. Experiments here include comparisons of: (1) egg survival from exposed "egg card" and protected "egg cup" release methods to assess the risk of agent predation and test mitigation strategies; (2) performance of egg cups overwintered at the release site and those placed shortly before emergence in spring to test for any potential phenological asynchrony between biological control agents and the target weed; and (3) effectiveness of egg cup and larval-inoculated stem releases at a large geographic scale across 15 field sites in southern Ontario. Egg card releases experienced high egg loss likely due to predation (∼90% of eggs), but egg cups were successful at reducing these losses to near zero. Releasing eggs in cups during the spring made it easier to place releases near phenologically synchronized microsites, minimized the risk of damage to the egg cups, and avoided a 16% reduction in egg hatch likely associated with desiccation. Both larval-inoculated stems and egg cups produced highly encouraging feeding damage in the first season of release, with 7.7-fold higher damage from stem larvae compared to egg cups. Overall, we recommend a combination of larval-inoculated stems and spring egg cups for the primary release strategies of A. neurica and L. geminipuncta as biological control agents of introduced Phragmites. Both methods offer protection from predation and varying degrees of control over phenological mismatches. The release of larval-inoculated stems is a more labour-intensive but highly effective method in terms of initial feeding damage whereas egg cups are a more efficient mass-release method than stems with a lower amount of initial feeding damage per agent released.

The box tree moth Cydalima perspectalis (Walker) (Lepidoptera: Crambidae) (BTM) is a native moth throughout eastern Asia, having recently become invasive in Europe (2007) where it feeds on boxwood (= box tree), Buxus spp. The moth rapidly spread across Europe and the Caucasus causing damage to both ornamental and wild Buxus. In 2018, C. perspectalis was found in Toronto, ON, Canada, and has since spread south into the US. To better predict where the moth will establish and have significant impact on ornamental trade in North America, we used most recent scientific literature and distribution points to update the temperature and diapause indices of an existing ecoclimatic CLIMEX model. The model parameters provided a good fit for the potential distribution of BTM compared to its known distribution across eastern Asia and in Europe. Interestingly, our results suggest that the current native distribution in Asia is incomplete and that further expansion is also possible in its introduced range, especially in northern Europe, along the Mediterranean coast of Africa, and eastward to central Russia. In North America, the model predicts that most of North America should be climatically suitable for the moth’s establishment, with the exception of Alaska and the northern territories of Canada, as well as higher elevations in the Rocky Mountains and southern hot and dry areas. Our study highlights the importance of the CLIMEX model to assess the risk of BTM spreading in its newly invaded areas, especially North America, and its use to help make decisions in terms of regulatory dispersal restrictions and choice of management options.