Do pesticide seed coatings break the promise of conservation agriculture?

Conservation agriculture improves soil quality and makes agricultural systems more resilient to biotic and abiotic stressors. There is growing evidence that conservation agricultural practices like no-till and cover crops can even help protect annual crops from insect pests by supporting resident predator communities. While adoption of conservation agriculture is growing, industrial field crop producers are also using an ever-increasing amount of neonicotinoid insecticide on crop seeds as a preventative insurance against early-season insect pests. This may disrupt the benefits associated with conservation agriculture by reducing biological control. Here, we investigated the interaction between preventative seed coats (PPM) and the conservation agriculture practice of cover cropping. In a three-year field experiment, we measured the response of invertebrate pests and arthropod predators to preventative and integrated pest management with and without a cover crop. We found that using any insecticide provided very little benefit to pest management and yield. Instead, cover early in the season was the most effective at reducing pest density and damage, largely because most arthropod predator groups were more abundant in high cover plots. Further, PPM decreased sentinel predation rates compared to a no pest management control (NPM). We suggest that the best pest management outcomes may occur when biological control is promoted. When pest populations in field crops are relatively low, cover crops may offer an exciting alternative to insecticide pest management.