Early-season soil insect pest pressure and IST efficacy against corn rootworm in Minnesota

Insecticide seed treatments (IST) are widely used in corn and soybean production to prevent injury from early-season insect pests. Neonicotinoids are the most widely used class of insecticides worldwide, and are frequently used in IST, also referred to as NST (neonicotinoid seed treatment). The widespread adoption of NSTs as a preventative measure has driven the increase in the use of neonicotinoids, accounting for more than 98% of the neonicotinoid treated acres in the most recent reports. However, questions have been raised regarding the benefits of NSTs as well as concern on the detrimental effects of neonicotinoids on pollinator species and the movement of NSTs into aquatic systems. Despite these concerns, there exists a gap in our knowledge of the actual pressure of early-season soil insect pests in Minnesota, as well as the efficacy of current ISTs in corn production. In this study, we conducted a two-year, statewide field survey across Minnesota to understand the prevalence of early-season insect pests in corn and soybean fields using multiple sampling methods. In addition, we evaluated the efficacy of ISTs in Bt and non-Bt corn fields against corn rootworm complex, another major target of ISTs. The findings generated provide valuable insights that can inform more judicious, region-specific, and evidence-based use of ISTs across Minnesota's agricultural landscapes.