In the largest and most accurate study to-date, researchers proved corn modified with the bacillus thuringiensis (Bt) trait has little effect on nontarget insects and additional organisms, especially when compared to growing non-GM corn.
Bt corn control corn borers, corn rootworms and other major pests of corn.
First approved in 1996, Bt corn remains polarizing despite its potential for more efficient crops. Critics believe Bt corn can destroy favorable insects and non-targeted organisms. Because of this, USDA wanted to take a wholistic look at all factors before making any assertions of danger or safety for these potential off-target impacts.
“Many field studies from Europe and other parts of the world have been published in the last decade, and those data are often not covered by previous meta-analyses. Therefore, we conducted a systematic review to answer the question: Does the growing of Bt maize change abundance or ecological function of non-target animals compared to the growing of non-GM maize?” explained the study.
Limited scope, environment or size reduced the value of past studies evaluating the impact of Bt corn. This new study compensated for these limitations by systematically gathering data from studies in “12 bibliographic databases, 17 specialized webpages and the reference sections of 78 review articles” that posessed the highest degree of research quality, according to a news release from USDA ARS.
“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,” said ARS entomologist Steve Naranjo, director of the U.S. Arid Land Agricultural Research Center in Maricopa, Arizona and an author of the study.
Naranjo and entomologists Joerg Romeis and Michael Meissle discovered this collection of data revealed Bt corn had no negative impacts on most invertebrate groups such as ladybeetles, flower bugs and lacewings. Communities of Braconidae insects, parasitoid wasps that attack corn borers, were decreased with Bt corn.
How Trustworthy Was Previous Research?
Researchers also examined if authorship or financial backing by biotechnology companies influenced the outcome of individual studies.
“It might be a bit surprising but according to the analysis, when any negative effects by Bt corn on nontarget organisms were found in the data, they were attributed more often in studies with private sector support than when no backing by biotech companies was declared,” added Meissle.
All studies included in the meta-analysis reached quality standards outlined by stakeholders, scientists detached from the study and members of the journal’s review board. None of the before mentioned parties knew if the study’s data exhibited negative impacts on non-target organisms or not.
“The result is the largest pool of high-quality data anyone has ever analyzed for this purpose consisting of 7279 individual invertebrate records from 233 experiments in 120 articles, 75 percent of which were from peer-reviewed journals,” said the news release.
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