Genetically engineered crops and pesticide use in U.S. maize and soybeans

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Science Advances  31 Aug 2016:
Vol. 2, no. 8, e1600850
DOI: 10.1126/sciadv.1600850

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  • RE: Pest resistance to genetically engineered Bt crops and insecticide use
    • Bruce E. Tabashnik, Regents' Professor and Department Head, Department of Entomology, University of Arizona

    Pest resistance to genetically engineered Bt crops and insecticide use

    Bruce E. Tabashnik, Department of Entomology,
    University of Arizona, Tucson AZ, 85721

    Perry et al. (1) provide a valuable analysis of the association between pesticide use and adoption of genetically engineered corn and soybeans in the United States from 1998 to 2011. They conclude that adopters of glyphosate tolerant (GT) crops increased herbicide use over this period, which they attribute in part to emergence of weed resistance to glyphosate. By contrast, they find no such increase for insecticide use on transgenic corn producing insecticidal proteins from Bacillus thuringiensis (Bt), which they state is “consistent with the evidence that non-Bt maize refugia have been broadly effective as a means to prevent the onset of pest resistance,” citing my 2008 paper (2). That paper explains how refuges of non-Bt host plants yield susceptible adults that can mate with resistant adults surviving on Bt crops and thereby delay evolution of resistance. It does note sustained susceptibility to Bt crops in five insect pests including the European corn borer (Ostrinia nubilalis), but also mentions two pests that had evolved resistance to Bt corn (one in the United States territory of Puerto Rico and the other in South Africa) and a third pest that had evolved resistance to Bt cotton. I proposed that in those three cases, the scarcity of refuges might have hastened resistance.
    Since 2008...

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    Competing Interests: Bruce Tabashnik is coauthor of a patent on modified Bt toxins, "Suppression of Resistance in Insects to Bacillus thuringiensis Cry Toxins, Using Toxins that do not Require the Cadherin Receptor" (patent numbers: CA2690188A1, CN101730712A, EP2184293A2,EP2184293A4, EP2184293B1, WO2008150150A2, WO2008150150A3). Bayer CropScience, Dow AgroSciences, DuPont Pioneer, Monsanto and Syngenta did not provide funding to support this work, but may be affected financially by publication of this letter and have funded other work by the author.