That little GMO could be losing its battle with insects

Is Bt corn in trouble? Some indications are that it is; that insects are infiltrating genetically engineered corn’s defenses. That has enormous implications for farmers using Bt corn seed, and for the U.S. food supply.

Andrea Parrish, writing on, said recently that less than two decades after planting of gentically modified organisms (GMO) commenced, corn fields resistant to pests are being attacked. Resistance to insects by Bt corn, she said, is weakened and root worms, once strongly resisted by Bt corn, are eating the GMO crops.

She said this loss of resistance threatens food prices. Corn in the U.S. enjoys sales of more than $15 billion a year. According to Parrish, a combination of this growing resistance to GMOs and the end of $6 billion in corn-based ethanol subsidies annually means that corn could get more and more expensive.

Parrish said the effect of higher corn prices will be higher food and fuel prices in the U.S. “When corn prices go up by as little as 10 percent, meat prices go up by as much as 25 percent,” she noted.

According to the Associated Press (AP), the emerging resistance of insects to Bt corn poses no immediate threats to the U.S. food supply, because the problem remains isolated to fields where farmers did not follow Bt instructions and continually planted Bt corn in the same fields year after year. But, said the AP, “Scientists fear potentially risky farming practices could be blunting the hybrid’s sophisticated weaponry.”

The AP said that in 2003, when Bt corn was introduced, it was deemed the answer to farmers’ insect problems on a large scale. The new corn would allow for super bountiful harvests with use of fewer expensive farm chemicals. In the intervening years, Bt has become king of the varieties, accounting for 65 percent of all corn planted in the U.S. However, evidence has been piling up in the last few summers that rootworms have begun feasting on the crop roots in part of four Midwestern states, “suggesting that some of the insects are becoming resistant to the crop’s pest-fighting powers.”

Pressure on corn supplies in recent years has caused some farmers to abandon rotation of crops in Bt fields because they need extra grain for livestock due to grain contracts with expanding ethanol producers. Others have gotten away from rotation so that they can cash in on continued high corn prices at market. Corn hit a record last June.

Similar damage to Bt corn has been seen in Iowa, Illinois, Minnesota, and Nebraska, but, said the AP, researchers are still investigating whether rootworms capable of surviving the Bt corn’s toxin were the cause. University of Minnesota entomologist Kenneth Ostlie told the AP that the severity of the rootworm damage has eased since discovery in 2009, “yet reports of damage have become more widespread, and he fears resistance could be spreading undetected because the damage rootworms inflict often isn’t apparent.”


For now, the AP said, rootworm resistance seems isolated, but scientists are afraid that may change if farmers don’t take quick action to follow Bt instructions for planting. They need to rotate crops and switch between Bt corn varieties, researchers noted.

Let’s be careful out there.

I’ll see ya.


An Iowa native, Peter Graham has been a rural newspaper editor for more than 40 years. He currently edits a twice-weekly paper in Western Iowa. You can contact him at (712) 642-2791 or [email protected] sourivalley