By Rady Ananda
Last week, 22 corn entomologists sent a letter to the US Environmental Protection Agency warning that insect resistance to genetically modified corn can be halted by planting non-GMO seed.
Increasing pesticide use or buffer zone size will not solve the growing problem of rootworm resistance to corn genetically modified with the bacterial Bt protein, Cry3Bb1, which we reported on last August.
“Likely contributing factors to the problem include the widespread use of Bt corn hybrids (or Bt corn + insecticide) where it is not economically justified, the repeated deployment of hybrids expressing the same toxin in the same fields year after year, violation of stewardship requirements for refuges, and decreased options to employ alternative forms of pest management,” said NCCC46 (North Central Coordinating Committee), a group of public researchers who support GM crops.
By “decreased options,” they mean that natural GM-free seed is not available to most farmers.
“Planting non-Bt corn can be profitable and should be one of the IPM [Integrated Pest Management] tools to maintain susceptibility to rootworm-protected transgenic corn,” they write in their letter.
NCCC46 also reports that “greater than expected damage to Bt corn hybrids expressing the Cry3Bb1 protein was first observed across a wide geographic area during the 2009 growing season.”
In response to their letter, Monsanto admits that in 2011, eleven states, including the entire cornbelt, had experienced rootworm resistance. But, it claims that “less than 0.2% of the acres planted with Monsanto rootworm-traited corn hybrids” are involved.
Biotech seeds involved in rootworm resistance include Monsanto and Dow’s SmartStax, Syngenta’s Agrisure, DuPont’s Herculex, and Monsanto’s YieldGard.
“All available evidence,” says NCCC46, implicates “field-evolved resistance to Cry3Bb1,” which Monsanto simply denied last year after the first paper confirming Bt resistance in the field was published in a peer-reviewed journal.
Though reports of field-resistance started in 2009, it was not until this year that the company finally recognized the problem.
As if unaware that the chemical companies selling transgenic seeds do so to sell pesticides, NCCC46 also blames farmers for over-use of pesticides. But, all of the hybrids discussed in the letter call for their use, as this Handy Bt Trait Table reveals.
NCCC46 also blames federal regulators for decreasing non-Bt refuge requirements from 20 to 5 percent. But, they warn of an increased resistant population even if refuge requirements were restored to earlier levels.
“Although many factors come into play, the always ‘on’ nature of transgenic toxins means they cannot be deployed or withdrawn in response to changing pest densities. Selection for resistance thus occurs wherever Bt corn is grown and susceptible insects are present.”
Confirmed resistance to the Bt protein Cry3Bb1 means that resistance to Cry34/35Ab1 and mCry3A will also develop when stacked, they said.
This is a perfect example of unintended consequences. Biotech is in its infancy, barely able to grasp the fallacy of one-gene, one-protein. So, they’ve stacked GM corn with more transgenic genes, but this will not stop insects from developing resistance. That’s what natural evolution is all about.
Though NCCC46 urges the planting of non-GMO corn to protect the Bt protein from becoming useless in transgenic pest management, biotech opponents can agree, but on the grounds of protecting the environment and public health.
Fiction: Michael Palmer's Oath of Office is a GM corn conspiracy thriller (2012, 374 p.)