Corn plants genetically engineered by Monsanto to repel pests are suffering severe damage from insects in more areas than previously reported, according to government scientists, who called the company's monitoring of the problem "inadequate."
In a memorandum posted this week by the U.S. Environmental Protection Agency, scientists reported that corn plants genetically engineered to kill the corn rootworm are showing signs of severe damage in Minnesota and Nebraska fields.
This past summer, researchers from Iowa State University and the University of Illinois reported damage in their states. At the time, those appeared to be the only states with reported damage. But the EPA memo, dated Nov. 22, said that reports of severe damage in Minnesota and Nebraska actually surfaced three and four years ago.
"Producers are reporting greater-than-expected damage, and investigators are trying to pinpoint the cause," said Mike Gray, an entomologist with the University of Illinois, who this summer found evidence of damage in Illinois fields. "EPA is saying: 'Hey. What's going on? We need to take these reports seriously.'"
The corn, first marketed in 2003 and now planted on 37 million acres, is engineered to express a protein — the Cry3Bb1 — that kills the rootworm when the pests eat the plants' roots. This summer, researchers from Iowa State published a report showing that the pest, one of the most damaging in agriculture, had evolved resistance to the protein. Monsanto says there has been no scientific confirmation of resistance.
In a written response to the EPA findings, Monsanto said it was taking the report seriously and was working with farmers to adopt best management practices in areas where the problem is more extreme. The company also pointed to newer products with 'stacked traits" that express an additional protein, saying those will provide farmers with a solution.
The company did not provide a representative for an interview.
The EPA memo recommends a "remedial action plan" to address cases of suspected resistance, which includes using conventional insecticides and another pest control approach in the following season. The agency cautioned that using a stacked-trait product — such as the company's new, highly touted SmartStax corn, which contains an additional protein — could lead to resistance to the second protein.
"They're saying that resistance will evolve more easily on the second protein," said Bill Freese, of the Center for Food Safety, based in Washington. "That's very important."
According to the EPA memo, Monsanto has not been doing investigations in enough cases because the company's threshold for testing is too low. The scientists also concluded that the company isn't testing samples close enough to the problem fields, and that the company may not have collected samples from all the fields where farmers reported problems.
Monsanto stocks dipped about 3.8 percent Friday.