"U.S. farmers are already receiving this benefit, even if they aren’t aware of it.” ~ Dr. Gary Munkvold
A couple of things are hard to control in the average grain storage bin: temperature and moisture. A bad combination of the two could lead to an infestation of insects and mold, resulting in mycotoxin contamination. Mycotoxins are toxic compounds that are naturally produced by certain types of molds. Molds that can produce mycotoxins grow on numerous foodstuffs such as cereals, dried fruits, nuts, and spices. These mycotoxins appear in the food chain due to mold infection of crops both before and after harvest.
A recent study at the Iowa State University (ISU) Seed Science Center (SSC) showed that farmers who plant Bt corn don’t have the same problems with insects and mold in storage compared to those who plant non-Bt corn. Bt is short for Bacillus thuringiensis and is enhanced through biotechnology to protect crops in the field from insect pests. But now researchers know it works post-harvest in storage. Researchers already knew Bt corn was resistant in storage against the Indianmeal moth, but they discovered something unexpected; a resistance to the maize weevil. Not only that, but in this study, the Bt corn was 100 percent effective against insects in the stored grain.
“The Bt resistance was developed specifically for field pests like European corn borer and corn rootworm. Previously it’s been shown that in the field, Bt insect resistance also helps protect against fungal infection and mycotoxins,” said Professor Gary Munkvold, ISU SSC. "There have been some studies on Bt resistance to storage insects but not with the added element of the storage molds. Also, those studies only included moth larvae. Showing resistance to weevils is new.
Nearly all corn grown in the United States is Bt seed; however, farmers in developing nations don't have access to better seed and resort to using insecticides to protect their crops.
“Farmers in developing countries, where they are not currently growing Bt corn, have more problems with stored corn because of the climate and the lack of climate-controlled storage facilities," Munkvold said. "The Bt corn is safe, and it provides yield stability and higher quality, safer grain when there is insect pressure, and allows farmers to avoid the hazards of applying insecticides.
Over two decades of review, the EPA and numerous scientific bodies have consistently found that Bt and engineered Bt-crops are not harmful to humans. On the other hand, insecticide exposure is linked to cancer, endocrine disruption, reproductive effects, neurotoxicity, kidney and liver damage, birth defects, and developmental changes in humans and animals.
Julie Mandap, Richard Hellmich, and Dr. Gary Munkvold performed this study.