Open Collections

Abstract

Agricultural intensification is often linked to declines in insect biodiversity. This association is largely attributed to factors such as land-use change, habitat fragmentation, and the frequent use of chemical controls. Yet agricultural fields may also support substantial numbers of insects across different insect guilds, particularly when management practices provide habitat for beneficial insects, including natural enemies that help control pest populations. Row management techniques, such as vegetative ground cover between rows, may offer important resources like food, shelter, and overwintering habitat for these insects. These practices have the potential to support greater natural enemy biodiversity within agricultural fields compared to bare ground between crop rows. To evaluate the response of the insect community to vegetative ground cover between rows, I surveyed insects in the Lower Fraser Valley of British Columbia, Canada, across 8 blueberry farms in 2021 and 2022. Farms either had inter row ground cover of grass and/or clover, or bare ground and/or mulch. Over two growing seasons, I sampled insects using a combination of apple cider vinegar traps, pitfall traps, and insect vacuuming to obtain metrics of abundance and diversity of pests and natural enemies in these farms. Vegetative ground cover appeared to support more insect natural enemies than bare ground when insects were sampled by vacuuming. Insect abundance in pitfall and baited traps did not differ between farms that had different row management techniques. Pest abundance showed no difference between ground cover and trap types, either overall or for the specific blueberry pest, Drosophila suzukii, commonly known as ‘spotted-wing drosophila’. However, my overall resolution of insect identity remained coarse, which may mask specific insect patterns. These findings underscore the complexity of supporting natural enemies in conventionally managed farms, with factors like prey availability, habitat structure, and management practices likely playing key roles in shaping natural enemy abundance and diversity. Future research should focus on identifying specific resources and habitat features required by natural enemies while incorporating robust sampling techniques to better understand pest and natural enemy dynamics.