Western corn rootworm beetles in the United States have grown immune to biotech crops that were originally designed to target the pests. The genetically modified organism (GMO) seeds, often referred to as Bt corn, were introduced in 1996—yet the rapid pace at which the insect has grown resistant has scientists and farmers worried.

Wired magazine explained the situation: “Until Bt corn was genetically altered to be poisonous to the pests, rootworms used to cause billions of dollars in damage to U.S. crops. Named for the pesticidal toxin-producing Bacillus thuringiensis gene it contains, Bt corn now accounts for three-quarters of the U.S. corn crop. The vulnerability of this corn could be disastrous for farmers and the environment.”

Scientists believe the immunity was brought on more quickly due to short-sighted agricultural practices.

The Associated Press wrote: “Researchers believe that rootworms are more likely to develop resistance to Bt corn when farmers plant the same hybrid in a field year after year, said Lance Meinke, an entomologist at the University of Nebraska-Lincoln.

“Most farmers rotate corn with other crops in a practice long used to curb the spread of pests, but some abandoned rotation to cash in on corn prices that stayed high for several years or because they needed more grain for livestock.

“But even with crop rotation, the beetles may be finding a way to thrive. Researchers are investigating reports that some corn rootworms in central Illinois found a way around crop rotation by laying eggs in soybean fields.”

The Lincoln Journal Star reported that there have been confirmed cases of Bt resistance in Nebraska, Iowa, Illinois, South Dakota, and Minnesota. Because rootworms have wings, the problem is expected to spread.