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Pesticide Use On Genetically Engineered Crops

Much has been written by scientific and mainstream media about the advantages of using genetically engineered (GE) crops because, according to popular belief, these crops require significantly less pesticide to control weed and insect pests. Or in slightly more sophisticated but equally misleading coverage, cursory acknowledgement is given to increasing herbicide use, but such increase is qualified in terms of the lower toxicity profile of glyphosate relative to more toxic herbicides that are also increasingly used. See e.g. Labels for GMO Foods Are a Bad Idea, Scientific American 8/20/13 “Because conventional crops often require more water and pesticides than GMOs do, the former are usually more expensive.”; Seeds of Doubt, New Yorker 8/25/14; The Promise of GMOs , Biology Fortified, 2/14/14; Environmental Benefits of Genetically Modified Crops , Fig. 7 CropLife, 11/02. These accounts are inaccurate and rely on annual pesticide application rates and volumes reported prior to 2010, when widespread resistance began to emerge in “superweeds” and “superinsects”. See Science What Happens When Weed Killers Stop Killing? 9/20/13; and Proceedings of the National Academy of Sciences Field-evolved resistance by western corn rootworm to multiple Bacillus thuringiensis toxins in transgenic maize 9/12/13. These reports also ignore the now widespread practice of coating seeds in systemic pesticides, which has emerged in the past 10 years. This lack of journalistic and scientific integrity distorts the facts on the ground.

In the United States, GE corn is planted on some 90 million acres, so the overuse of undesirable pesticides on this crop can have profound effects on the natural ecosystem, including beneficial organisms. GE corn makes up over 90 percent of US corn acreage as of 2014, with 76 percent “stacked” with both insecticide producing (Bt) and herbicide tolerant (Roundup Ready) traits. The latter enables heavy use of the herbicide glyphosate on food crops. (USDA’s “Recent Trends in GE Adoption.”)

Many of us are unaware that in addition to the ever-increasing spraying of glyphosate and the presence of genetically engineered insecticidal Bt toxin in every cell of every GE crop plant, massive amounts of other pesticides (herbicides, insecticides, fungicides) are applied to genetically engineered food crops. The continuing massive overuse of pesticides – along with the failure to use refuge set-asides, the failure of GE corn to produce desired levels of Bt toxin and financial incentives for corn-on-corn planting cycles – have collectively resulted in the selection of pesticide-resistant weeds and insects, leading to ever more pesticide applications. ( Bt Corn Farmer Compliance with Insect Resistance, AgBioForum; Biofuels  Incentives:  A  Summary  of  Federal  Programs, Congressional Research Service 1/11/12) This is now termed “the chemical treadmill.

Chemical companies that historically have produced DDT, PCBs, bovine growth hormone, Agent Orange, glyphosate products and, more recently, neonicotinoids have inserted themselves squarely into the seed crop production component of the world’s food supplies. These corporations have a clear conflict of interest when it comes to reducing the numbers and concentrations of chemicals on crops, because any such reduction has an immediate impact on their financial bottom line. There is also a clear conflict of interest when it comes to altering farm management to avoid insect and weed resistance if it results in using fewer chemicals. As University of Nebraska entomologist Lance Meinke says, “economics are driving everything.” ( As Biotech Seed Falters, Insecticide Use Surges In Corn Belt Morning Edition, NPR, 6/9/13.)