An old bug might have learned a new trick in Illinois’ corn fields, outsmarting a strain of corn genetically engineered to produce its own insecticide.
It’s called the Western corn rootworm. And while farmers have battled the pest for decades, Midwestern crop scientists are now scrambling to figure out whether the larvae and adult bugs have developed into a super-bug, capable of eating corn that ought to kill it.
If that’s the case, this little super-bug - which has been spotted in DeKalb and LaSalle counties - may cause big headaches for farmers come spring planting season, weakening roots until a stiff breeze can topple the plant.
“We’re always on the lookout for something,” said Steve Pitstick, who farms roughly 2,100 acres of corn and soybeans near Maple Park. “It seems like every year there’s some event that pummels us, so we’re always trying to look for that and be ready to act on it.”
For nearly the past decade, Pitstick - like many farmers across the country - has been relying on a genetically engineered strain of corn, called Bt corn, to fend off the corn rootworm and other pests. The corn is spliced with Bacillus thuringiensis, a bacterial toxin that kills various kinds of insects. The genetic modification helped farmers control pests in corn, potatoes, cotton and other crops while using less chemical insecticide.
But this past summer, researchers sampling fields in Iowa discovered Bt corn crops infested with the root-munching bug that the genetically altered corn was supposed to kill.
Two-thirds use it
About 65 percent of the nation’s cornfields are planted with Bt corn, which has saved American farmers millions in lost crops and chemical insecticides.
“We have not been able to confirm Bt resistance,” said Michael Gray, crop scientist at the University of Illinois. “But we’re cooperating with Iowa State, we’ve collected adults (corn rootworms) from the field, and the offspring of those adults will give us a better indication this spring.”
According to Gray, crop scientists in Iowa have been able to confirm that the bugs there have grown resistant to Bt corn, but it will take another growing season to determine whether Illinois’ corn rootworms have evolved resistance to the altered corn.
After growers called him with reports of blighted crops last summer, Gray said he has confirmed rootworms living among Bt corn crops, first in Henry and Whiteside counties near the Iowa border.
In September, a grower in LaSalle County reported root damage among his Bt corn crops. Test crops of Bt corn at a research site near DeKalb have also turned up rootworms.
Part of the reason the rootworm is, well, taking root is the amount of corn planted and replanted on Illinois fields. Corn planted year after year in the same field gives the bugs more time to adapt and evolve a resistance to the bacterium that is supposed to kill them.
Not rotating
While Illinois’ farmers often avoid this problem by rotating corn and soybeans in their fields, record-high prices for corn have also driven farmers to follow corn with corn for multiple years.
Farmers are also required by law to plant non-Bt corn among 20 percent of their crops to serve as a refuge for insects. That way, if a rootworm or other insect develops a super-bug resistance to the Bt toxin, it would more likely mate with a regular bug and produce non-resistant offspring.
But Pitstick said that crop rotation, which he has practiced throughout his 35 years as a farmer in Kane County, doesn’t always work to keep the pests away.
“As long as I’ve been farming, we’ve battled with rootworms in corn,” Pitstick said. “We used to be able to rotate crops to fend them off, and then Mother Nature adapted and no longer left us with that as an option, so then we had to start using soil-applied insecticide.”
Now, he said, he plans to return to those applied insecticides - in addition to planting a new hybrid of Bt corn - since Mother Nature appears to have adapted again.
Those are two options suggested by researchers to fend off the bug and keep any possible resistance from spreading in 2012. Gray also suggests that farmers who saw poor yields or root damage last year consider a switch to soybeans this year.
Many, though not all, farmers have already made their decisions on what crops will go where and which seeds will be planted this April, and both farmers and researchers will be watching closely to see what the insects have in store.
“Now, for whatever reason, Mother Nature is starting to adapt again,” said Pitstick, “And we may be looking for plan B.”
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