Eating a combination of non-toxic and genetically modified Bt corn can cause corn earworm pests (Helicoverpa zea) to develop wings that are longer, narrower, and more tapered. These changes make the moths’ wings resemble those of fighter jets and may allow them to travel greater distances, according to new research from North Carolina State University.
The study found that when corn earworms consume a blend of toxic Bt corn—engineered to produce pest-killing toxins—and a smaller amount of toxin-free corn, their wing shape changes significantly within just one generation. The altered wings are stiffer and better suited for flight in high wind conditions.
“Wings from insects eating a blended toxic and non-toxic corn diet were stiffer and more able to travel in higher wind speeds,” said Dominic Reisig, professor and extension specialist of entomology at North Carolina State University and co-corresponding author of the paper. “These insects are able to get up into the winds and ride them longer distances.”
Researchers compared four groups: moths raised on blended corn diets; moths raised solely on non-Bt corn; moths raised exclusively on Bt corn with two toxins; and those raised on Bt corn with three toxins. Most commercial U.S. corn and cotton crops contain Bt toxins for insect control.
Corn earworms typically feed on various crops including soybeans, tomatoes, cotton, as well as corn itself. Reisig explained their prevalence by saying: “Corn is basically like a factory for this insect. Corn earworm can overwinter in our state, slowly build up its generations early in the season, and then in July, when corn silks, those moths go in and lay eggs, Almost every single ear of corn produces at least one caterpillar that becomes a moth when it grows up. That’s a lot of bugs. All of that activity also funnels into cotton and soybeans, and that’s why they’re such a big problem.”
The study revealed that only the group fed the blended diet developed wings optimized for long-distance flight after one generation. Moths fed other diets had less aerodynamic wings that were more brittle or deformed.
“It appears that resistance occurs faster when worms eat these blends, creating individual moths that have multiple resistance mutations,” Reisig said. “This is one more piece of evidence that blending Bt and non-toxic corn pollen is really dangerous for resistance.”
Reisig noted ongoing work examining how different diets affect mating success among these pests.
The paper was co-authored by K M Mikac, M J Powley, S Barclay (University of Wollongong), J H Dominguez Davila (South Coast Structural Engineers), D Pezzini, along with Dominic Reisig from NC State University. The research was published November 19, 2025 in Environmental Entomology (DOI: 10.1093/ee/nvaf117).
Funding came from the U.S. Department of Agriculture’s National Institute of Food and Agriculture through a Biotechnology Risk Assessment Grant (project award no. 2018-33522-28741) as well as support from a University Global Partnership Network grant (2022-23).
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