Functional vegetative strips associated with beneficial entomofauna in a polyculture system in Québec, Canada

Abstract: Diverse hedgerows promoting functional biodiversity were implemented on an
ecological polyculture farm located in southwestern Québec, Canada. This study explored the
potential of these hedgerows to support natural enemies of two cruciferous crop pests and
pollinators of cucurbits. In 2018 and 2019, the abundance and diversity of natural enemies were measured on ten selected plant species. Larval and pupal parasitism rates of major lepidopteran pests were evaluated in crucifer plots adjacent to hedgerows, along with pollinator abundance and diversity in cucurbit plots. Achillea millefolium (Asteraceae), Symphytum × plandicum (Boraginaceae) and Caragana arborescens (Fabaceae) supported the highest number of hymenopteran parasitoid families targeting crucifer-defoliating caterpillars. Parasitism rates of Pieris rapae and Plutella xylostella larvae ranged from 34.4 % to 65.4 %, depending on species and years. The hedgerows were also associated with Lasioglossum sp. and Peponapis pruinosa, known to be effective pollinators of cucurbits. This project contributes to supporting evidence for ecological services provided by vegetative strips in polyculture systems.