Until Bt corn was genetically altered to be poisonous to the pests, rootworms used to cause billions of dollars in damage to U.S. crops. Named for the pesticidal toxin-producing Bacillus thuringiensis gene it contains, Bt corn now accounts for three-quarters of the U.S. corn crop.
But who didn’t see this coming?
After years of predicting it would happen and after years of having their suggestions largely ignored by companies, farmers and regulators scientists have documented the rapid evolution of corn rootworms that are resistant to Bt corn.
This could have been forestalled, at least to a certain extent:
Key to effective management, said the scientists, were refuges set aside and planted with non-Bt corn. Within these fields, rootworms would remain susceptible to the Bt toxin. By mating with any Bt-resistant worms that chanced to evolve in neighboring fields, they’d prevent resistance from building up in the gene pool.
But the scientists’ own recommendations an advisory panel convened in 2002 by the EPA suggested that a full 50 percent of each corn farmer’s fields be devoted to these non-Bt refuges were resisted by seed companies and eventually the EPA itself, which set voluntary refuge guidelines at between 5 and 20 percent.
Elson Shields, a Cornell entomologist, is wholly unsurprised:
There’s a lesson to be learned for future crop traits, Shields said. Rootworm resistance was expected from the outset, but the Bt seed industry, seeking to maximize short-term profits, ignored outside scientists. The next pest-fighting trait “will fall under the same pressure,” said Shields, “and the insect will win. Always bet on the insect if there is not a smart deployment of the trait.”
And once again, man is done in by his obsession with quarterly revenue reports.