Farmers Turn to Pesticide as Insects Resist Genetically Modified Crops

Genetically modified seeds were supposed to liberate corn farmers from using pesticide to combat rootworms. But as the insects adapt, farmers are having to adapt—by spraying their fields with chemicals.

It’s not just the cicadas. The Wall Street Journal reports there’s a more significant insect threat being posed to America: rootworms.

The bugs, which have the capability to decimate corn and grain crops, have become a more manageable problem in recent years. That’s because companies like Monsanto have developed genetically modified seeds that produce rootworm-killing toxins—without harming humans. (Here’s Monsanto’s rootworm page.) Thanks to the widespread adoption of such seeds, farmers have been spraying their crops with insecticide less frequently. “Today, according to the U.S. Department of Agriculture, two-thirds of all corn grown in the U.S. includes a rootworm-targeting gene known as Bt,” the Journal reports.

But if you’ve read your Darwin, you’ll know that species have been known to adapt to circumstances. And that seems to be happening in the corn fields. Some rootworms apparently were immune to the nasty stuff in the seeds. And they have been reproducing. The upshot? Farmers are bringing back the chemicals. In addition to purchasing the rootworm-proof seeds, they’re now having to start using insecticides. Companies like Syngenta, which makes soil insecticides for corn crops, are reporting booming sales.

Genetically modified crops have been touted as a solution to many of the woes afflicting agriculture. The theory was that scientists could rearrange the chemical makeup of crops so that they could resists the perils posed by drought, or heat, or pestilence. But while you can fool nature for a while, it’s apparently difficult to do so over the long term.