A study published in the Oct. 8 edition of the journal Science, finds that widespread planting of genetically modified Bt corn throughout the Upper Midwest has suppressed populations of the European corn borer, historically one of corn’s primary pests.
The area wide suppression has dramatically reduced the estimated $1 billion in annual losses caused by the European corn borer, even on non-genetically modified corn.
Bt corn, introduced in 1996, is so named because it has been bred to produce a toxin from the soil bacterium Bacillus thuringiensis (Bt) that kills insect pests.
Corn borer moths cannot distinguish between Bt and non-Bt corn, so females lay eggs in both kinds of fields, says William Hutchison, professor of entomology at the University of Minnesota.
Once eggs hatch in Bt corn, young borer larvae feed and die within 24 to 48 hours. Because it is effective at controlling corn borers and other pests, Bt corn has been adopted on about 63 percent of all U.S. corn acres.
As a result, corn borer numbers have also declined in neighboring non-Bt fields by 28 percent to 73 percent in Minnesota, Illinois and Wisconsin, depending on historical pest abundance and level of Bt-corn adoption.
The study, the first to show a direct association between Bt corn use and an area wide reduction in corn borer abundance, documents similar declines of the pest in Iowa and Nebraska.