It is a frequent and crucial claim that herbicide-resistant and pest-resistant GMOs reduce pesticide use, with large benefits for farmers and the environment. A systematic, independent, and publicly accessible analysis of this claim is now provided in: Impacts of genetically engineered crops on pesticide use in the U.S. — the first sixteen years by Charles Benbrook (2012).
Assessing the “impacts of six major transgenic pest-management traits on pesticide use in the U.S.,” Benbrook found that, “herbicide-resistant crop technology has led to a 239 million kg increase in herbicide use in the U.S., between 1996 and 2011, while Bt crops have reduced insecticide applications by an estimated 56 million kg.” Therefore, due to the use of GMO seed-pesticide systems, between 1996-2011, “Overall pesticide use increased by an estimated 183 million kg, or about 7%.” However, when levels of plant-produced insecticide (i.e. transgenic Cry endotoxins) and not just applied insecticide were included for Bt GMOs, Benbrook found that on average Bt crops actually greatly increased insecticide use. Furthermore, transgenic Bt insecticides are not environmentally degraded before crop consumption, being produced within the plant cells themselves, which has likely greatly increased human and livestock insecticide exposure.
Benbrook discusses the root causes of the increased pesticide use seen in GMO systems. These include rapid emergence of glyphosate-resistant weeds, increases in potency of non-glyphosate herbicides, high levels of insecticide production in Bt crops, and the use of Bt insecticide producing plants in situations where insecticides would not have been used to control for corn borer or rootworm. He predicts that as herbicide-resistant weeds and Bt-resistant insects continue to emerge, pesticide use will further increase.
While showing these cropping systems have high economic costs for farmers and also the public, Benbrook notes that “The seed-pesticide industry is enjoying record sales and profits, and the spread of resistant weeds and insects opens up new profit opportunities in the context of the seed industry’s current business model.”
With no incentive for the seed-pesticide industry to change course, it is up to farmers, citizen groups, non-profits, and government to implement alternatives to GMO seed-pesticide systems and to reinvigorate non-GMO plant breeding (1). Without immediate and strong intervention, U.S. agriculture will continue with its increasingly harmful reliance on GMOs, herbicides, and insecticides.
(1) For some alternatives to industrial agriculture and GMO seed systems see: