Monsanto Co. and other seedmakers reported a threefold increase last year in U.S. farmers caught violating rules intended to stop insects from developing resistance to genetically modified corn.
The rules affect farmers planting seeds modified to produce a toxin derived from Bacillus thuringiensis, or Bt, a natural insecticide. The Environmental Protection Agency requires those growers to also plant an adjacent area — a so-called refuge — of non-Bt corn so that bugs feed on both types of corn and don’t become immune to the toxin.
About 41 percent of 3,053 farmers inspected in 2011 failed to fully comply with the refuge requirement, according to data that Monsanto provided last week in an e-mail.
Seed companies are concerned that bugs’ resistance to modified crops may be increasing. In July, Iowa State University found that some rootworms have evolved resistance to the Bt gene engineered into Monsanto corn. Entomologists in Illinois and other Midwestern states are studying possible resistance in fields where the insects devour roots of Monsanto’s Bt corn.
Seed companies used sales data to identify farmers who may not have purchased enough seed for a refuge, said Nick Storer, global science policy leader for Dow Chemical Co., another maker of modified seeds.
“The whole purpose of doing that was to try to increase the frequency with which we identify non-compliant growers,” Storer said in an interview.
Farmers who violate the requirements are now revisited at least twice over five years, Joanne Carden of Monsanto said in an interview. Farmers who fail the follow-up inspection lose access to the technology, she said.