The study evaluated specific GM crops like corn and cotton that have been infused with a genetic mutation involving the bacterium Bacillus thuringiensis (Bt), as well as several other toxins that grow inside the plant to target pests. This so-called "pyramid" strategy, which involves using multiple GM toxins to target the same pests, is said to have been designed for the purpose of thwarting pesticide and insecticide resistance by targeting pests with two or three different toxins all at once rather than just one at time.
But according to the UA report, insects and other pests are outsmarting this approach. After evaluating a series of laboratory experiments they conducted, as well as various computer simulations and other published data on the subject, the team learned that multi-toxin GM crops do not necessarily kill pests redundantly -- that is, if a pest is resistant to one toxic GM trait, it does not necessarily respond automatically to the other toxic GM traits. In fact, the pest response to multi-toxin GMOs is so complex and unpredictable that it is already shaping up to be a complete failure.
"[T]he team's analysis of published data from eight species of pests reveals that some degree of cross-resistance between Cry1 and Cry2 toxins occurred in nineteen of twenty-one experiments," explains Homeland Security News Wire about the study's findings. Cry1 and Cry2 are two types of GM toxins used in conjunction with each other in some multi-toxin GM crops. "Contradicting the concept of redundant killing, cross-resistance resistance means that selection with one toxin increases resistance to the other toxin."
"Our simulations tell us that with 10 percent of acreage set aside for refuges, resistance evolves quite fast, but if you put 30 or 40 percent aside, you can substantially delay it," says Yves Carriere, a professor of entomology at the UA College of Agriculture and Life Sciences and lead author of the study. "Our main message is to be more cautious, especially with a pest like the cotton bollworm," he adds, referring to a common crop pest that has already developed resistance to both Cry1 and Cry2.
Earlier research out of UA that was published in the Journal of Economic Ecology warned that western corn rootworm beetles are also growing resistance to multi-toxin GMOs. Like the new paper, this previous study urged that larger acreages of pest refuges be installed to help slow the problem, although this intervention admittedly will not solve the problem forever.