Field-Evolved Resistance to Bt Maize by Western Corn Rootworm

By A. Gassmann, J. Petzold-Maxwell, R. S. Keweshan, Mike W Dunbar. PLoS ONE, 2011

659 citations recorded by the source corpus.

Background Crops engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are planted on millions of hectares annually, reducing the use of conventional insecticides and suppressing pests. However, the evolution of resistance could cut short these benefits. A primary pest targeted by Bt maize in the United States is the western corn rootworm Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae). Methodology/Principal Findings We report that fields identified by farmers as having severe rootworm feeding injury to Bt maize contained populations of western corn rootworm that displayed significantly higher survival on Cry3Bb1 maize in laboratory bioassays than did western corn rootworm from fields not associated with such feeding injury. In all cases, fields experiencing severe rootworm feeding contained Cry3Bb1 maize. Interviews with farmers indicated that Cry3Bb1 maize had been grown in those fields for at least three consecutive years. There was a significant positive correlation between the number of years Cry3Bb1 maize had been grown in a field and the survival of rootworm populations on Cry3Bb1 maize in bioassays. However, there was no significant correlation among populations for survival on Cry34/35Ab1 maize and Cry3Bb1 maize, suggesting a lack of cross resistance between these Bt toxins. Conclusions/Significance This is the first report of field-evolved resistance to a Bt toxin by the western corn rootworm and by any species of Coleoptera. Insufficient planting of refuges and non-recessive inheritance of resistance may have contributed to resistance. These results suggest that improvements in resistance management and a more integrated approach to the use of Bt crops may be necessary.

Subfields: Insect Science, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/78cc3b58742543085c56bf29b5685f6f7c9c7a2a

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Citations in the corpus

Impacts of genetically engineered crops on pesticide use in the U.S. -- the first sixteen years (2012, background): “Stable reductions in insecticide use in Bt-transgenic corn are also now in jeopardy as a result of the emergence of corn rootworm (CRW) populations resistant to the Cry 3Bb1 toxins expressed in several corn hybrids [1,2].”
Genetically Engineered Crops in the United States (2014, background): “Recently, western corn rootworm larvae were collected from Iowa Bt cornfields that showed evidence of root damage, and laboratory assays later confirmed that their progeny were less susceptible to Bt toxins (Gassmann et al., 2011).”
Bacillus thuringiensis insecticidal three-domain Cry toxins: mode of action, insect resistance and consequences for crop protection. (2013, background): “It has been shown that insects can develop resistance to Bt toxins in the laboratory and to Bt sprays in the field (Ferré & Van Rie, 2002; Janmaat & Myers, 2003; Tabashnik et al., 2008; Kruger et al., 2009; Storer et al., 2010; Dhurua & Gujar, 2011; Gassmann et al., 2011; Zhang et al., 2011).”
No scientific consensus on GMO safety (2015, positive): “to Bt toxins has emerged in target pests [42], and problems with secondary (non-target) pests have been noted, for example, in Bt cotton in China [43,44].”