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The spotted wing drosophila Drosophila suzukii Matsumura (Diptera: Drosophilidae), a pest of berries stone fruits, invaded North America and Europe in 2008. Current control methods rely mainly on insecticides. The sterile insect technique (SIT) has potential as an additional control tactic for the integrated management of D. suzukii. As a step towards the development of the SIT, this study aimed at finding the optimum irradiation dose to sterilize D. suzukii under controlled laboratory conditions. Four-day-old D. suzukii pupae were irradiated 12 to 24 hours prior to adult emergence in a 60Co Gamma Cell 220 and in a 137Cs Gamma Cell 3000 with doses of 30, 50, 70, 80, 90, 100 or 120 Gy. Emergence rate (88.1%), percent of deformed flies (4.0%) and survival curves were not affected by the tested irradiation doses. However, some reproductive parameters of the flies were affected by irradiation. Females irradiated with a dose of 50 Gy or more had almost no fecundity. When non-irradiated females were mated with irradiated males, egg hatch decreased exponentially with irradiation dose from 82.6% for the untreated control males to 4.0% for males irradiated with 120 Gy. Mortality of F1 individuals from the irradiated treatment also occurred during larval and pupal stages, with an egg to adult survival of 0.2%. However, descendants produced by the irradiated generation were fertile. These results are an encouraging first experimental step towards the development of the SIT for the management of D. suzukii populations.

Understanding the causal pathways through which forest insect outbreaks are triggered is important for resource managers. However, detailed population dynamics studies are hard to conduct in low-density, pre-outbreak populations because the insects are difficult to sample in sufficient numbers. Using laboratory-raised larvae installed in the field across a 1,000 km east–west gradient in Québec (Canada) over an 11-yr period, we examined if parasitism and predation were likely to explain fluctuations in low-density spruce budworm (Choristoneura fumiferana; SBW) populations. Parasitism rates by the two main larval parasitoid species, Elachertus cacoeciae and Tranosema rostrale, peaked during different years. This suggests that temporal fluctuations in overall parasitism were partly buffered by compensatory dynamics among parasitoid species. Still, spatial covariance analyses indicate that the residual interannual variation in parasitism rates was substantial and correlated over large distances (up to 700 km). On the other hand, interannual variation in predation rates was not spatially correlated. Piecewise structural equation models indicate that temporal variation in parasitism and predation does not influence temporal variation in wild SBW abundance. Spatially, however, SBWs installed in warmer locations tended to show higher parasitism rates, and these higher rates correlated with lower wild SBW population levels. Overall, the results indicate that large-scale drops in parasitism occur and could potentially contribute to SBW population increases. However, during the period covered by this study, other factors such as direct effects of weather on SBW larval development or indirect effects through host tree physiology or phenology were more likely to explain large-scale variation in wild SBW populations.

The egg parasitoid Trichogramma spp. (Hymenoptera: Trichogrammatidae) is a widely used biocontrol agent against lepidopteran pests. Historically, Trichogramma were deployed either by plane or by using cardboard cards on which parasitized eggs are glued and manually installed at sites. Plane deployment is costly and card installation is time consuming, but the use of Trichogramma has been shown to be efficient against several pests. In 2016 and 2017, a research project investigated the potential use of unmanned aerial system for distributing Trichogramma as biocontrol agents against two major pests: an agricultural pest of maize, the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), and a forest pest, the eastern spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera:Tortricidae). Exposure duration of parasitized eggs to field conditions (temperature, predation, etc.) in maize fields influenced the Trichogramma's emergence rate, suggesting that timing of parasitoid releases with their emergence is essential. Although parasitism of naturally occurring eggs in maize fields could not be compared due to the low density of the European corn borer, parasitism of sentinel eggs by Trichogramma was more prominent in plots with unmanned aircraft systems (UAS)-releases compared to control plots. For spruce budworm, treatment with Trichogramma increased egg parasitism and there was no difference between the deployment by UAS and by Trichocards. We discuss these results in the context of pest biology and management. We also discuss the advantages and shortcomings of both methods and offer insights into where future work might go to further leverage the use of UAS in managing these important pests.

Exotic insect species are an increasing concern with international trade. Detecting and removing any insect are thus important for any imported/exported product, including wood products. For example, wood transportation is known to be an important pathway for the introduction and dispersal of the Emerald Ash Borer, Agrilus planipennis (Coleoptera: Buprestidae). This Asian species is causing high mortality of ash trees in its introduced range because of the weak natural defense of trees and the virtual absence of natural enemies. For similar reasons, there are concerns in Europe that the Bronze Birch Borer, A. anxius, native to North America, could be introduced and cause important birch mortality. Having efficient detection methods and phytosanitary measures to prevent introducing it is thus important. In this study, we evaluated tomodensitometry—or CT-scan—as a detection method for detecting these two Agrilus spp. using debarking as the method of reference. Using CT-scan, we were also able to precisely measure the depth of insects in ash and birch trees in order to recommend proper phytosanitary measures for exportation and importation of wood products. Both techniques efficiently detect the presence of insects in ash, paper birch, and yellow birch. However, the number of A. anxius detected depended on both the technique and the diameter of the sample. The depth of insects depended on tree species, sample diameter, and life-stage. Globally, A. planipennis are deeper in ash trees than A. anxius in birch trees, and prepupae are deeper than larvae. The maximal depth in the sapwood (excluding bark thickness) for ash, paper birch, and yellow birch was 21.9 mm, 6.30 mm, and 3.22 mm, respectively. While CT-scan is more expensive and requires access to expensive equipment, debarking is more time-consuming, especially if the number of insects needs to be determined.

Narrow-spectrum insecticides are currently used to control populations of spruce budworm, Choristoneura fumiferana Clemens (Lepidoptera: Tortricidae), in eastern Canada. However, these could have nontarget impacts on other caterpillars – some of which may serve as alternative or alternate hosts to key parasitoids – that are also susceptible to control tactics. This study was conducted to determine how the insecticides, Bacillus thuringiensis variety kurstaki (Btk) and tebufenozide, used to control spruce budworm populations, impact caterpillar communities and associated parasitism rates. Post-treatment field sampling of caterpillars was conducted in 2018 and 2019 in New Brunswick, Canada, at sites treated with either Btk or tebufenozide and at control sites. Caterpillar species richness and abundance, community structure, and parasitism rates were assessed using molecular analyses for 659 collected caterpillars. We found that insecticide applications had no significant impact on abundance, species richness, or parasitism rate relative to the measurements made in the control sites. Nonetheless, a significantly higher caterpillar abundance and lower parasitism rate occurred in Btk-treated sites than in tebufenozide-treated sites. Overall, however, Btk and tebufenozide treatments did not negatively affect the non-budworm caterpillar community under the present conditions of low caterpillar densities, suggesting that parasitoids have alternative and alternate hosts after treatments that target the spruce budworm.

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.

Four ligands based on the 2-tert-butyl-4-X-6-Bis[(6-methoxy-pyridin-2-ylmethyl)-amino]-methyl-phenol unit are synthesized: X = CHO (HLCHO), putrescine-pyrene (HLpyr), putrescine (HLamine), and 2-tert-butyl-4-putrescine-6-Bis[(6-methoxy-pyridin-2-ylmethyl)-amino]-methyl-phenol (H2Lbis). Complexes 1, 2, 3, and 4 are formed upon chelation to copper(II). The crystal structure of complex 1 shows a square pyramidal copper center with a very weakly bound methoxypridine moiety in the apical position. The pKa of the phenol moiety is determined spectrophotometrically at 2.82–4.39. All the complexes show a metal-centered reduction in their CV at Epc,red = −0.45 to −0.5 V vs. SCE. The copper complexes are efficient nucleases towards the ϕX174 DNA plasmid in the presence of ascorbate. The corresponding IC50 value reaches 7 μM for 2, with a nuclease activity that follows the trend: 2 > 3 > 1. Strand scission is promoted by the hydroxyl radical. The cytotoxicity is evaluated on bladder cancer cell lines sensitive (RT112) or resistant to cisplatin (RT112 CP). The IC50 of the most active complexes (2 and 4) is 1.2 and 1.0 μM, respectively, for the RT112 CP line, which is much lower than cisplatin (23.8 μM).

This article is the third and last of a series of models developed to investigate the impact of climate on the spatiotemporal biology of parasitoids. After two earlier papers investigating Tranosema rostrale and Meteorus trachynotus, this last article concerns the tachinid fly Actia interrupta (Diptera: Tachinidae). An individual-based model of the seasonal biology of A. interrupta was developed to determine the impact of climate on its interactions with two of its hosts, the spruce budworm Choristoneura fumiferana (Lepidoptera: Tortricidae) and the obliquebanded leafroller C. rosaceana in eastern North America. The model is based on the developmental responses of ‘the parasitoid’s successive life stages and the ovipositional response of adult females to temperature. It was found that the number of generations this parasitoid undergoes each year varies geographically from two to four, and that its potential growth rate, as dictated by synchrony with larvae of its overwintering host C. rosaceana, is highly patterned geographically and topographically as a result of phenological matching with larvae of obliquebanded leafroller entering diapause in late summer.

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a serious pest of ash (Fraxinus spp.) (Oleaceae) in North America. Control of emerald ash borer is difficult in natural forest settings; therefore, a classical biological control programme is the most feasible management option for this invasive, nonnative insect. Here, we report the first Canadian release and establishment of parasitoids Tetrastichus planipennisi Yang (Hymeoptera: Eulophinae), Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae), and Spathius galinae Belokobylskij and Strazanac (Hymenoptera: Braconidae) in natural forests in Ontario, Quebec, and New Brunswick, Canada for the control of emerald ash borer. Releases of T. planipennisi were made from 2013 to 2019, O. agrili from 2015 to 2019, and S. galinae from 2017 to 2019. Trees from release sites were destructively sampled to rear out adult emerald ash borers and parasitoids 1–3 years after parasitoid release. Recoveries of T. planipennisi were made at 81% of release sites (13 of 16) 1–2 years after release, and O. agili were recovered from 29% of release sites (4 of 14) 1–3 years after release. Spathius galinae was not recovered. These data provide important information for the development and deployment of a successful biological control programme for the management of emerald ash borer in Canada.

Despite their importance as mortality factors of many insects, the detailed biology and ecology of parasitoids often remain unknown. To gain insights into the spatiotemporal biology of insect parasitoids in interaction with their hosts, modeling of temperature-dependent development, reproduction, and survival is a powerful tool. In this first article of a series of three, we modeled the biology of Tranosema rostrale at the seasonal level with a three-species individual-based model that took into account the temperature-dependent performance of the parasitoid and two of its hosts. The predicted activity of the first adult parasitoid generation closely matched the seasonal pattern of attack on the spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae). The model predicted 1–4 full generations of T. rostrale per year in eastern North America. The generations were generally well synchronized with the occurrence of larvae of a probable alternate host, the obliquebanded leafroller Choristoneura rosaceana (Lepidoptera: Tortricidae), which could be used as an overwintering host. Spatial differences in predicted performance were caused by complex interactions of life-history traits and synchrony with the overwintering host, which led to a better overall performance in environments at higher elevations or along the coasts. Under a climate warming scenario, regions of higher T. rostrale performance were predicted to generally move northward, making especially lower elevations in the southern range less suitable.