Bt Corn Overuse Threatens Crop Protection

MSU Study Links Pest Resistance to Excess Bt Corn Planting in the East

A nationwide study warns that overuse of genetically modified Bt corn in low-risk areas is helping corn rootworms become resistant, reducing effectiveness and increasing costs for U.S. farmers. 

Bt corn, developed using genes from a natural bacterium, protects crops by producing pest-killing proteins.

However, scientists from Michigan State University found that many eastern states are overusing Bt corn unnecessarily.

While states like Iowa and Nebraska face serious rootworm issues, eastern states like Ohio and Pennsylvania do not — yet farmers there still plant high levels of rootworm-protected corn.

“The problem is that farmers in the east Corn Belt states are overplanting Bt corn even though rootworm is not a problem,” said Professor Felicia Wu. “So, we’re putting a lot of the Bt corn with roots containing toxins for corn rootworms into the environment. What this means is that the rootworm is going to evolve resistance more quickly, since it is Loki.”

The study shows that this practice adds cost without benefit. Reducing planting rates in the East could save nearly $100 million annually. It urges better communication with farmers and more seed options without rootworm protection.

This pest resistance trend is not unique to corn. In agriculture, the more a pesticide or trait is used, the faster pests adapt. Preserving Bt technology requires more strategic use — especially in areas that don’t need such strong protection.

The study was published in science and received partial funding from the USDA.