UNDERSTANDING NON-TARGET INSECTICIDE IMPACTS AND OPPORTUNITIES FOR BIOLOGICAL CONTROL IN FIELD CORN

Abstract

Natural enemies can be important regulators of pest populations, replacing chemical pesticides, or where compatible complementing them. To effectively incorporate these biological control services into crop production, we need to understand how pesticides and other management practices impact natural enemies, pests, and their interactions with one another. Using Mid-Atlantic field corn production systems, I evaluated at-planting insecticides and transgenic Bt corn hybrids as tools for insect pest control. In addition, I quantified their impact on predation and on carabid beetle communities. Carabid beetles may be important predators of pest slugs; therefore, I also examined carabid-slug interactions. Finally, I investigated whether a novel pest-management technique (RNAi) could travel up the food chain through pests to predators. At-planting insecticides provided limited pest-management benefits in a three-year field study across Maryland, suggesting that their use could be scaled back to reduce environmental and economic costs. Field and lab experiments revealed carabid beetles are diverse and abundant in corn fields, and a slug predatory carabid species may exert non-consumptive effects on a pest slug. Finally, I determined that a predatory lady beetle species is likely less susceptible to RNAi oral exposure in the adult stage. However, RNAi may still pose risks to predators via trophic exposure. My work supports the adoption of current and future corn pest management practices that protect natural enemies, enhancing biological control ecosystem services and their associated environmental benefits.