Overwintering sites and natural enemies of squash bugs in cucumber greenhouses in Quebec, Canada

Squash bugs Anasa tristis and A. armigera (Heteroptera: Coreidae) are sporadic pests in Québec (Canada) cucumber greenhouses. These bugs can cause important damage to cucumber, and the only control method is the manual removal of individuals by producers. The main objective of this project is to gain knowledge of the biology of the squash bugs in greenhouse vegetable production that will allow the development and optimization of control methods. The specific objectives are 1) to identify the predators of the squash bug, and 2) to identify favourable overwintering sites. Observations in three greenhouses per year have been done weekly between June and September 2020 and 2021. Specimens were captured and kept in the laboratory for parasitism evaluation. To evaluate overwintering sites, at the end of September, 30 individuals were introduced into cages containing four types of substrates: 1) soil with rocks; 2) soil with pieces of wood; 3) soil with crop residues, and 4) soil. Containers were kept outside for the winter period, and individuals were removed in the spring. A few natural enemies were observed in 2022, mainly spiders. In addition, the parasitoid Trichopoda pennipes (Diptera: Tachinidae) was identified. During the recovery of individuals from overwintering substrates, the majority of A. armigera and A. tristis individuals were found in soil + crop residues in 2021. In 2022, more A. armigera individuals were found in crop residues. Better knowledge of the life cycle of squash bugs in cucumber greenhouse will help develop an IPM strategy against those pests.