KELLY MCEVERS, HOST:
Most of the corn that's grown in America is genetically modified so it can defend itself from a destructive insect called the corn rootworm, but that defense is starting to fail. And now scientists are reporting they found a new weapon - another insect-killing gene they can put into corn. NPR's Dan Charles has more.
DAN CHARLES, BYLINE: For all the international furor about genetically modified food or GMOs, the biotech industry has really only managed to put a few foreign genes into food crops. The first of those genes came from a kind of bacteria in the soil called Bacillus thuringiensis, or Bt. Those Bt genes produce a protein that makes plants poisonous to certain insect pests, including the corn rootworm, which is really destructive.
TOM GREENE: It's a billion dollar pest.
CHARLES: This is Tom Greene, a senior research director for DuPont Pioneer, a big biotech and seed company. The Bt genes that fight the corn rootworm are a pillar of the industry that sells biotech seeds. But that pillar is starting to wobble. In some places, the genes are not working so well. Corn rootworms have evolved. Many now can eat the genetically modified corn just fine.
So scientists at DuPont Pioneer have been searching among the countless types of bacteria that live in the soil, looking for some that are lethal to the rootworm. Many people have carried out similar searches and failed. DuPont Pioneer scientists succeeded.
They found a rootworm-killing microbe, and they inserted the gene that makes the lethal protein into corn plants. As they'd hoped, it worked just like Bt. The corn plants killed rootworms. They announced their success in this week's issue of the journal Science.
GREENE: This is a very important discovery because it does represent - we can find very efficacious proteins from non-Bt sources.
CHARLES: Now, the biotech industry and farmers can't celebrate quite yet. Greene says this new weapon against the rootworm won't be available for a decade or so. His company will have to convince regulators that it's safe for people and for the environment.
And Fred Gould, who co-directs the Genetic Engineering and Society Center at North Carolina State University, says he hopes that the industry's learned some lessons from the history of the Bt genes. If you overuse a gene like this, it won't work for long.
Years ago, he says, when the Bt genes were still new, a group of scientists warned the Environmental Protection Agency, don't let farmers plant corn with this gene on all their fields. It'll force corn rootworms to evolve far more quickly. Before you know it, the genes won't work anymore.
FRED GOULD: The majority of the people on that EPA Science Advisory Panel recommended a 50 percent refuge. That means 50 percent of the corn that would go out could have the Bt, and 50 percent would not.
CHARLES: Seed companies, though, persuaded the government to let farmers plant up to 95 percent of their acres with this Bt corn. It encouraged farmers to rely on genetic engineering instead of old fashioned methods for controlling pests like planting a variety of crops, not just corn. Gould says if this new gene goes on sale, he's hoping that regulators limit its use so it stays effective for many years longer than the Bt genes have. Dan Charles, NPR News.
NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.