Genetically modified Bt corn has little effect on non-target insects and other organisms, especially compared to conventional corn farming, which uses broad-spectrum insecticides, according to a systematic review of hundreds of individual studies published on June 6, the Agricultural Research Service (ARS) of the U.S. Department of Agriculture (USDA) says.
The study, “the largest, highest quality analysis of data ever conducted” on the subject, was carried out by a USDA ARS scientist and his Swiss colleagues and published on June 6 in Environmental Evidence, according to the ARS.
Biotechnology has been used to improve Bt corn’s resistance to insect pests, offering the corn built-in insect protection provided by a naturally occurring microbe known as Bacillus thuringiensis, or “Bt,” the ARS says. The protein generated by Bt corn targets the European corn borer, a moth larva that feeds on cornstalks and ears, causing yield losses projected at more than $1 billion per year.
Since Bt corn was approved by the U.S. Environmental Protection Agency in 1996, “critics have been suggesting that it also can destroy beneficial insects or other non-targeted organisms,” and studies were conducted to confirm this suspicion.
Hundreds of studies reviewed
In this latest review, “literature published until August 2019 was searched systematically in 12 bibliographic databases, 17 specialized webpages, and reference sections of 78 review articles.”
“We gathered together hundreds of individual studies published between 1997 to 2020 that have looked at whether growing Bt corn changed the environmental abundance of non-target animals such as arthropods, earthworms and nematodes, especially as compared to growing non-genetically modified corn accompanied by the pesticide necessary to control major pests,” entomologist Steve Naranjo, director of the U.S. Arid Land Agricultural Research Center in Maricopa, Arizona and one of authors of the study, tells the ARS. “After all the number crunching was done, what we found was that, overall, Bt corn just does not have negative impacts on nontarget organisms.”
The ARS maintains: “This major meta-analysis largely proved out previous individual studies. Bt corn represents a highly selective pest control technology with relatively few negative consequences for non-target invertebrates, especially when compared with the use of broad-spectrum insecticides for managing Bt-targeted pests, according to the scientists.”
