Bugs resistant to genetically modified corn found

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LINCOLN, Neb. (AP) — Researchers say bugs are developing
resistance to the widely popular genetically engineered corn plants that
make their own insecticide, so farmers may have to make changes.
The Lincoln Journal Star reports (http://bit.ly/1eC05SM ) that cases of rootworms
eating roots of so-called Bt corn have been
confirmed in Nebraska, Iowa, Illinois, South Dakota and Minnesota.
Iowa
State University researchers found that rootworms have developed
resistance to two of the four genetic traits in corn plants that are
engineered to kill rootworms. Iowa State professor Aaron Gassmann said
the problem isn’t widespread yet, but farmers and seed companies should
consider changing their approaches to pest control.
"Hopefully, people can learn from these cases of resistance," Gassmann said.
The
popular corn variety gets its name from the insect-killing bacterium it
contains, bacillus thuringiensis, a natural insecticide that is
considered harmless to people and livestock. The U.S. Department of
Agriculture reports that 76 percent of all corn planted last year was Bt
corn.
When rootworms attack, clumps of corn plants can be leveled by summer storms because they don’t have the
roots to anchor them.
In areas where Bt corn has failed to control rootworms, farmers often turn to insecticides.
Researchers
believe that rootworms are more likely to develop resistance to Bt corn
when farmers plant the same hybrid in a field year after year, said
Lance Meinke, an entomologist at the University of Nebraska-Lincoln.
Most
farmers rotate corn with other crops in a practice long used to curb
the spread of pests, but some abandoned rotation to cash in on corn
prices that stayed high for several years or because they needed more
grain for livestock.
But even with crop rotation, the beetles may
be finding a way to thrive. Researchers are investigating reports that
some corn rootworms in central Illinois found a way around crop rotation
by laying eggs in soybean fields.
The problem of resistant rootworms could easily spread because the larvae grow into adult beetles that
can fly to new areas.
Meinke
said farmers should think of Bt corn as just one part of their strategy
for managing rootworms. He said it doesn’t appear likely that seed
companies will be able to make significant improvements in the corn
hybrids in the next few years.
"Right now there is nothing on the
horizon for the next four or five years that is going to come out. So we
have to manage rootworms with what we have," Meinke said.
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Information from: Lincoln Journal Star, http://www.journalstar.com
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