Insect scientists say federal regulators need to take action against a growing pest problem in biotech corn.
They say corn rootworm has started to become resistant to Monsanto's Bt corn, which is genetically engineered to resist the damaging and costly pest.
The 22 scientists expressed their concerns in a letter sent to EPA earlier this week.
University of Illinois insect behaviorist Joseph Spencer was one of them.
He says farmers can't just rely on a single pest management strategy.
“We can't rely on just Bt," Spencer said. "We need to think about using a mix of techniques to assure that we can protect the corn that we're growing in the United States."
Monsanto spokesperson Danielle Stewart says the company has been working closely with corn farmers who had crop damage last season. (Read Monsanto's full response)
"The vast majority of farmers experienced excellent performance on more than 99.8 percent of the acres planted with Monsanto corn rootworm traits in 2011," Stewart said. "And we are working closely with farmers, academics and the EPA to evaluate reports of greater-than-expected corn rootworm damage in certain fields."
Farmers have also experienced resistance problems with other genetically-engineered crops.