A new study from Michigan State University reveals that excessive planting of genetically modified Bt corn in the eastern U.S. Corn Belt is accelerating pesticide resistance in corn rootworms, a devastating pest. The research, published in Science, highlights how overplanting in low-risk areas undermines the crop’s effectiveness and increases costs for farmers.
Bt corn, engineered to produce natural insecticides from the soil bacterium Bacillus thuringiensis (Bt), was designed to combat corn rootworms. However, the study found that farmers in eastern states like Ohio, Michigan, and Pennsylvania are planting Bt corn varieties unnecessarily, as these regions face lower rootworm pressure compared to western states such as Iowa and Illinois.
Lead author Felicia Wu, a professor at MSU, likened the rootworm to the trickster “Loki” for its ability to evolve resistance to pesticides and even crop rotation. “The more Bt corn we plant, the faster resistance develops,” Wu explained. This overuse has led to rising seed costs and diminishing returns, with the study estimating that reducing Bt corn planting in the East could save farmers $99 million annually and nearly $2 billion over time.
“Farmers in the East are overplanting Bt corn despite minimal rootworm threats,” said Wu. “This not only wastes resources but speeds up resistance, jeopardizing the technology’s long-term viability.”
The study urges a strategic reduction in Bt corn use in low-risk areas and advocates for diversified seed options to preserve its effectiveness. Wu emphasized the need for better communication with farmers to balance agricultural innovation with sustainability.
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