In a giant case of “we told you so”, a group of scientists from Iowa State University published a report this week citing evidence that corn rootworms have evolved to become resistant to genetically modified Bt corn. The artificially engineered plant contains genes from Bacillus thuringiensis that allow the cells to produce toxins that used to kill large numbers of corn worms and root borers. Despite warnings raised by the scientific community, farmers and seed companies planted large swaths of Bt corn without creating non-engineered corn refuges, thereby facilitating the pest’s resistance. Now, Bt corn accounts for three-quarters of the U.S. corn crop, and is in great danger of being wiped out by superbugs.
Bt corn was first planted in 1996 and was responsible for a huge decrease in the midwest’s population of rootworms and corn borers. Fewer pests translated into larger harvests and less need for conventional pesticides. Unfortunately, scientists began to see signs of trouble only ten years after the corn’s introduction. Experts urged farmers to set aside plots that supported other breeds of corn, but warnings were not heeded due to lobbying by biotech companies and lack of regulation. By 2009, Iowa State University reported that they found massive damage to one of three varieties of Bt corn from rootworms in the northeast corner of the state, and in 2011 they witnessed resistance in South Dakota, Minnesota, Nebraska, and Illinois.
In the latest Iowa State University study co-authored by Aaron Gassmann, research indicates that rootworms in Iowa have become resistant to a second type of Bt corn. Observations suggest that even Bt corn manipulated to produce multiple toxins at once are also vulnerable. Since Bt corn can still kill other pests, Gassmann predicts that farmers will continue to plant the crop as well as increase the use of pesticides. Sadly, by adding chemicals back into the mix, the overall environmental benefits from modified corn disappears.
To avoid a plague of Biblical proportions, researchers strongly suggest that farmers plant multiple crops on their land and set aside plots for other types of corn. Without a lack of diversity, no amount of engineering in the world will protect corn from its persistent predators.
Images via the USDA