Some GMO Crops Are Losing Their Resistance To Pests Some of the first GMOs – corn and cotton plants that have been genetically modified to fend off insects – are running into problems. Bugs have become resistant to them because they've been overused.

As Biotech Crops Lose Their Power, Scientists Push For New Restrictions

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Some of the most widely used agricultural biotech products are running into problems. These corn and cotton plants that have been genetically modified to fend off insects have been great for the environment and for farmers. But now they're not working as well, and top scientists say it's because they have been overused. Here's NPR's Dan Charles.

DAN CHARLES, BYLINE: These crops got their superpower from bacteria that live in the soil called bacillus thuringiensis, or BT. These bacteria are poisonous to insects like corn rootworm and cotton bollworm. So scientists inserted some of their genes into corn and cotton, and the plants themselves now kill those pests. They were the original GMOs, genetically modified organisms - not the first ones invented but the first ones that were a big success on the farm. David Kerns, an insect specialist at Texas A&M University, says all of a sudden, cotton farmers didn't have to spray so much.

DAVID KERNS: Our insecticide sprays just plummeted, and there were guys that wouldn't have to treat it all.

CHARLES: This brought lots of environmental benefits. BT is an amazing insecticide. It's not toxic to people or birds. It's almost harmless to beneficial insects like bees and butterflies. And farmers like Jonathan Evans in North Carolina didn't have to work so hard.

JONATHAN EVANS: It's always better for the plant to protect itself than for us to have to go out and try to spray for the worms.

CHARLES: Did it really change farming?

EVANS: Absolutely. I mean, you can tend a lot more acres with a whole lot less equipment.

CHARLES: All those benefits are now at risk. New strains of insects have emerged. They've become resistant to one BT gene after the other, and those insects are eating the crops. David Kerns says some farmers are disappointed and angry.

KERNS: There's words I can't use, but they wanted to know what the heck they're doing paying for a technology and then they're still having to spray.

CHARLES: University scientists actually predicted that this would happen if the genes were overused. Years ago, some of them pushed for regulations that would keep farmers from planting more than half of their land with some of these BT crops. They didn't succeed. Now scientists like Julie Peterson at the University of Nebraska are pushing once again for tighter government rules.

JULIE PETERSON: We are at an important point where we've seen some examples of what can happen and definitely do need to make some changes.

CHARLES: The biggest changes are aimed at trying to preserve one particular BT gene. It's called Vip3A, or just Vip. Vip came on the market a little later, and it's slightly different from other BT genes.

PETERSON: So it still is effective against a lot of insects, and it's sort of carrying a lot of the weight. Right now.

CHARLES: Scientists are worried that it'll soon break under the weight of overuse, especially in the South, where the Vip gene is used in both corn and cotton to fight off an insect that feeds on both crops. The Environmental Protection Agency's scientific advisers have told the agency it should prohibit the use of Vip in corn in the South. Just use it in cotton, they said, where it's much more valuable. That way, it's more likely to keep working. But the company that owns the Vip gene, Syngenta, says that's not necessary or fair, and the EPA has backed away from the idea. Scientists say it's possible that all the BT genes will stop working reliably within 10 years.

Dan Charles, NPR News.


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