Neonicotinoid seed treatments do not consistently reduce insect feeding damage nor increase yields in Maryland soy

The use of neonicotinoid insecticides in seed treatments in the United States has increased drastically since the mid‐2000s, but it is difficult for farmers to directly evaluate their efficacy because of the lack of availability of untreated seed.

We observed plants from both treated and untreated seeds of a commercial soybean variety over 12 site‐years (4 sites × 3 years) in the University of Maryland Soybean Variety Trial. Sites ranged from the foothills of the Appalachian mountains to the Atlantic coastal plain, covering much of the physiographic and climatic variation of the mid‐Atlantic region.

Neonicotinoid seed treatments (NST) did not provide consistent reduction in insect feeding damage (chewing or stippling) throughout the experiment. Furthermore, treated seeds showed no increase in soybean yield compared to untreated seeds.

Our results show no benefits from NST to Maryland soy production. This lack of benefits, along with the conflict between preventative pesticide use and the principles of integrated pest management (IPM), adds to a large body of evidence that NST should be avoided to minimize health risks for humans and the environment.