It looks like Dow-DuPont’s genetically modified Herculex corn is no longer controlling the western bean cutworm. This corn was engineered to express a protein called Cry1F, toxic to the pests that feed on corn kernels and lead to fungus growth. This control failure is the latest in a series that are collectively undermining the efficacy and value of Bt insecticidal corn technology.
In the early years, growers mostly adhered to carefully thought out resistance management plans, plans that worked well and prevented widespread resistance. But because such plans included a sizable refuge that could not be planted to a corn variety with a Bt trait, sales were constrained. The companies convinced the EPA to back off refuge requirements, relying instead on the mixing of different Bt traits “in the bag,” following the logic of “if the right don’t get you, then the left one will.” Instead, the mixing and stacking of multiple traits has accelerated cross-resistance to multiple Bt toxins. Now, the technology is in big trouble, and so are farmers who have come to rely on it.
This article sites several incidences where GE crops are losing effectiveness, including Monsanto’s YieldGuard corn that was supposed to be immune to the western corn rootworm, as well as their Roundup Ready crops that are supposed to be tolerant to herbicides.
Jack Kaskey, “Du-Pont’s Modified Corn Fails to Control Pests, Scientists Say,” October 19, 2016, Bloomberg Markets