"A new study adds to evidence that farmers in the US corn belt have over-planted a type of genetically modified (GM) corn, leading to estimated losses of more than $1 billion as the pests the corn was designed to repel have grown resistant over time.

The authors of the paper, published Thursday in the journal Science, said their findings supported a move toward a “more diversified” seed supply.

Known as Bt corn because it contains up to five toxins produced by a bacterium called Bacillus thuringiensis, the specialty corn is designed to express proteins that make the plant toxic to certain pests, including corn rootworm.  More than 85% of corn planted in the US is the Bt variety, to which various insect pests are becoming resistant.

After examining rootworm crop damage data from 10 states over the period 2005-2016, the researchers determined that many farmers planted more GM corn than was considered necessary to address pest problems. Bt seeds typically carry a significant price premium."

Douglas Main reports for The New Lede February 27, 2025. [2]