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Originally published December 29 2014

Crop-destroying armyworms develop resistance to pesticidal GMOs

by David Gutierrez, staff writer

(NaturalNews) A crop-devastating pest known as the armyworm has begun developing resistance to genetically modified organisms (GMOs) designed to kill it, according to a study conducted by researchers from Louisiana State University, North Carolina State University (NCSU), the University of Florida, the U.S. Department of Agriculture (USDA), the University of Minnesota and the University of Georgia, and published in the journal PLOS ONE on November 17.

Armyworms are a potent predator of major agricultural crops including corn, cotton and soy, and cost farmers in the South tens of millions of dollars per year.

Armyworms are actually the caterpillar form of a species of moth (Spodoptera frugiperda) and are typically very vulnerable to the pesticides produced by plants genetically engineered (GE) to carry a gene from the bacteria species Bacillus thuringiensis (Bt). The fact that pests are now starting to develop resistance to Bt poses "a great threat" to the future of GMO crops, the researchers said.

Bt crops have only been on the market for 18 years, but in that time have been widely adopted across the Americas.

"Wake-up call"

In fall 2013, a North Carolina farmer called NCSU entomologist Dominic Reisig and asked him to figure out why his corn plants were disintegrating. Reisig discovered that armyworms were responsible -- but the corn in question was Bt, and supposedly invulnerable to armyworms.

Reisig collected samples of the caterpillars and tested them against both Bt and non-Bt corn that he grew in his greenhouse. The armyworms happily ate both varieties. So Reisig sent some of the caterpillars to Louisiana State University researcher Fangneng Huang.

In prior research, Huang had discovered Bt-resistant armyworms in Florida and Louisiana. Huang confirmed that the North Carolina caterpillars were some of the most Bt-resistant that he had ever tested. Notably, it was the farthest north that resistant armyworms had ever been found.

"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. "Resistance happens, and it's a stark reminder that we need to take steps -- such as planting non-Bt 'refuge' crops near the Bt crops -- to limit the development of resistant insect strains."

Because armyworms cannot survive freezing temperatures, they are typically not a major threat to North Carolina corn crops. Researchers fear, however, that the resistant caterpillars will discover the region's cotton fields.

"That would be problematic, since cotton usually begins producing fruit (the marketable cotton bolls) in late July or early August -- when fall armyworm populations have grown," Reisig said.

"We've done greenhouse studies and found that this Bt-resistant armyworm can certainly eat genetically modified cotton; we just haven't seen it happen in the field yet."

GMO "arms race"

The resistant caterpillars are only the latest in an emerging problem of "super-pests" driven by GMOs. Evidence of Bt resistance has also been seen in another insect pest, the western corn rootworm.

Other than Bt, the major trait inserted into GM crops is resistance to the herbicide Roundup (glyphosate). The widespread adoption of "Roundup Ready" crops in the 1990s led to a corresponding surge in Roundup use. Now the effects of that are being felt in an explosion of Roundup-resistant superweeds.

The industry's response to the superweeds problem has been to engineer Roundup Ready crops to also resist another deadly herbicide, 2,4-D. A similar attitude is echoed in the armyworm study, which suggests increasing use of chemical pesticides to combat resistant caterpillars.

"This is part of a growing problem, an escalating chemical arms race going on across America's heartland," wrote the Center for Food Safety at "Dow Chemical is hyping GE 2,4-D corn and soy as the solution to resistant weeds, but GE crop systems caused the 'superweeds' in the first place."


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