Interactive effects of cover crops and native plantings on beneficial and pest insects in soybean

Agroecosystem diversity generally benefits ecosystem services. For example, rotating target crops with cover crops can enhance soil health and establishing native perennial plant habitat can augment biological control and pollination services. While the benefits of individual diversity practices have been documented, it is not well understood how these practices interact to influence beneficial and pest insects. This study investigates the interactive effects of in-field cover crops and adjacent native plantings on insect predator and herbivore populations in soybean agroecosystems. Soybean fields across the Northeastern and central regions of Missouri were sampled in 2023 using pitfall traps and sweep nets. The presence of cover crops or native habitats reduced herbivore abundance in soybean fields, likely due to the higher overall ratio of predators to herbivores. However, there was spatial variation in the effect such that herbivore abundance was lower and predator abundance was higher in areas of the field closer to native habitat plantings. We also detected a significant interaction whereby the benefit of the native planting was mediated by the presence of cover crops, with stronger responses in fields where cover crops were used than without cover crops. These results confirm that cover cropping and native perennial plantings promote insect predators and suppress insect herbivores, but also suggest an even greater benefit for soybean ecosystems when multiple diversity practices are used simultaneously.