Researchers confirmed that fall armyworms in North Carolina are resistant to a variety of corn genetically engineered to produce a protein toxic to the insects. It is the first documented occurrence of insect resistance to so-called Bt (Bacillus thuringiensis) corn in 18 years of use, said Entomology Today. It quoted entomologist Dominic Reisig of North Carolina State University, who was involved in the research, as saying, “This is a huge wake-up call for farmers north of Louisiana and Florida — this is definitely something to keep an eye on.”
Reisig said the discovery was “a stark reminder that we need to take steps…to limit the development of resistant insect strains.”
Tests showed the armyworms were resistant to the Cry1F protein but not to other Bt proteins, such as Cry2Ab2 or Vip3A, nor to Bt varieties that contain more than one of the proteins. Reisig said growers should plant non-Bt “refuges” as a method to prevent insect resistance. University of Georgia professor David Buntin said good stewardship of Bt technology was vital and that growers should use corn varieties with more than one Bt toxin.
Entomology Today said “cotton farmers should also take heed because the Cry1F-resistant armyworms could impact WideStrike cotton, a variety that also contains the Cry1F protein.”
The armyworms probably originated in Puerto Rico, scientists said, based on genetic tests. The migratory insect cannot survive winter weather in North Carolina.