Promoting Pesticide Resistance
Monsanto's RoundupReady and Bt technologies lead to resistant weeds and insects that can make farming harder and reduce sustainability.
Deja Vu All Over Again? Bt Resistance in the Western Corn Rootworm
In August 2011, a scientist at Iowa State University published a peer-reviewed paper showing that at some locations in Iowa, rootworms (a major corn pest) had developed resistance to one of the two main types of commercialized Bt toxins engineered into Monsanto's insect-resistant corn. If this resistance spreads, it could lead to increased insecticide use.
(In Bt crops, a gene from a soil bacterium that produces an insect toxin has been inserted into the crop's genetic material.)
To maintain the efficacy of Monsanto’s rootworm product, the EPA requires that farmers plant some portion of their acreage with non-Bt corn. If resistant rootworms emerge from Bt fields, this “refuge” supplies non-resistant rootworms to mate with the few resistant individuals that survive on Bt corn, thus diluting the genetic pool of resistance.
A majority of independent academic scientist advisors told the EPA that farmers planting corn containing the Bt toxin Cry3Bb1 should use a 50 percent refuge. However, the biotech industry and a minority of scientists convinced the agency to require only a 20 percent refuge. This has probably contributed to the rise of resistant rootworms.
Monsanto has responded much as it did to early reports of resistance to glyphosate—denying that resistance has been verified, which could encourage complacency, while recommending practices that could make the problem even worse.
For instance, at the top of Monsanto's list of recommendations for farmers that face "significant corn rootworm pressure"—the company's euphemism for suspected Cry3Bb1 resistance—is to use corn varieties that contain both Cry3Bb1 and another Bt toxin that has been approved for rootworm control, Cry34/35.
But research and theory show that where insects have developed resistance to one Cry toxin, the probability of resistance to the second toxin is greatly increased. Monsanto’s recommendation would therefore jeopardize not only Cry3Bb1, but also the other Bt toxin most widely used for rootworm control. It would, however, allow Monsanto to sell more of its product.
But there's a catch.
Enter the Superweeds
Beginning around 2000, weeds growing in Roundup Ready crops began to develop resistance to Roundup (glyphosate), the Monsanto herbicide that Roundup Ready crops are genetically engineered to tolerate. By 2011, eight agriculturally important weeds in the U.S. had developed glyphosate resistance associated with Roundup Ready crops.
Glyphosate-resistant weeds now infest millions of acres of U.S. cropland—and this area has been growing rapidly over the past several years. Countries where Roundup Ready crops were more recently introduced are now beginning to see similar growth in resistant weeds.
These "superweeds" are causing huge problems for U.S. farmers, especially in the Southeast (but also spreading in the Midwest), where some of these weeds cannot be effectively or economically controlled. The impact on cotton production has led one scientist to compare a glyphosate-resistant weed to the notorious boll weevil, which devastated cotton production across the American South in the 1920s.
In response, farmers are increasing their overall herbicide use (see #2) and in some cases, returning to heavy tillage (plowing), which can increase soil erosion—thus reducing two of the sustainability benefits claimed for the Roundup Ready system.
Making Matters Worse
Why is this problem growing so fast? Because the Roundup Ready system encourages unprecedented reliance on a single herbicide—which, as biologists know, is likely to make resistance problems more severe. Pest resistance is not a new problem, but Roundup Ready technology has made it worse than before.
And Monsanto exacerbated the problem by discouraging farmers from employing typical resistance management approaches, such as alternating the types of herbicides used over time—which would have reduced the amount of Roundup used in any given year, and thus cut into the company's bottom line. This led a group of academic weed scientists to publicly contradict Monsanto's recommendations and reiterate scientifically-based methods for reducing the resistant weed problem.
Adding insult to injury, Monsanto representatives were described in a 2009 ABC News story as blaming farmers for overuse-related resistance problems.
Sacrificing Sustainability for Sales
Monsanto's pronouncements and recommendations about its engineered crops and glyphosate herbicide fly in the face of established science and common-sense precautions. Its actions have undermined the goal of weed control and jeopardized long-term use of glyphosate—a less toxic, less persistent, and more effective herbicide than most others—in favor of the company's annual bottom line. This is the opposite of good stewardship and sustainable practices. Monsanto's denialism and inadequate responses are likely to contribute to greater environmental harm.