Effects of cover cropping and landscape diversity on insect pests, predators, and pollinators in cereal-dominated landscapes of inland Pacific Northwest, USA

In response to climate change, agricultural production systems worldwide are adapting diversified cropping systems such as incorporating cover cropping into business-as-usual (e.g., wheat-fallow) crop rotations. Cover cropping in cereal-dominated landscapes of the inland Pacific Northwest (iPNW) is in its early years of experimentation, so there are no studies on how cover crops affect pests and beneficial insect communities at the field and landscape scale. To compare insect communities between cropping systems in 2019 and 2020, we sweep net-sampled 26 cover crops and 26 wheat fields during peak flowering of cover crops in the iPNW. We calculated landscape diversity (i.e., crop diversity) within 250 m, 500 m, 1000 m, and 2000 m radii from each cover crop or wheat field's centers based on NASS-Cropland Data Layer. A total of 13 271 specimens from 80 families were collected. We found that the abundances of pests and pollinators were greater in cover crops than in wheat, while predator abundance was similar. Path diagram showed that cover crop richness was positively associated with predators and pollinators but not pests. Pollinators were positively associated with the landscape diversity at 1000 m and 2000 m radii suggesting cropping system diversification and landscape diversity work together to increase the biodiversity of these taxa.