2nd Place: D3038: Classical biological control of spotted-wing drosophila: Will introduced natural enemies be able to survive cold Canadian winters?

In the last decade, control of the spotted wing drosophila (SWD) (Drosophila suzukii) in berries has mostly relied on chemical control. However, two Asian larval parasitoids are considered for classical biological control: Leptopilina japonica and Ganaspis brasiliensis (Hymenoptera: Figitidae). Both species have already established in the Vancouver area, since 2016 and 2019 respectively. The introduction of G. brasiliensis has now been approved in the United States and parts of Europe.

Before releasing these parasitoid species in eastern Canada, overwintering survival must be studied to determine their potential of establishment. Following diapause induction in the laboratory, individuals of both species were placed outdoors in padlocked briefcases in December 2021. Two sites were evaluated: Montréal area and Québec City, both important berry production regions. The Montréal area is warmer and has less snow accumulation than Québec City. The insulating effect of snow was also evaluated: briefcases were placed at 0 m (with snow cover) and at 2 m (without snow cover). Parasitoids were brought back to the laboratory in mid-February and at the end of April to determine overwintering survival and timing of the spring emergence. No adult parasitoids of both species emerged in 2022. Results from this study will provide valuable information on the potential establishment of two foreign biological control agents against the SWD in Northeastern America.