Journal Article

Field-Evolved Resistance to Bt Maize by Western Corn Rootworm

Gassmann, Aaron J., Dunbar, Mike W., Keweshan, Ryan S., Petzold-Maxwell, Jennifer L.

2011

Overview

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). 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. 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.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Agriculture / Agrochemicals / Animals / Bacillus thuringiensis / Bacillus thuringiensis - pathogenicity / Bioassays / Biology / Biopesticides / Bt gene / Cereal crops / Chrysomelidae / Coleoptera / Coleoptera - growth & development / Coleoptera - microbiology / Corn / Correlation / Crops / Cutting resistance / Diabrotica virgifera virgifera / Endotoxins - toxicity / Evolution / Farmers / Farms / Feeding / Gelechiidae / Genetically altered foods / Genetically engineered foods / Genetically engineered organisms / Genetically modified crops / Helicoverpa / Heredity / Insect control / Insecticide resistance / Insecticide Resistance - genetics / Insecticides / Larva - growth & development / Larva - microbiology / Lepidoptera / Noctuidae / Pectinophora gossypiella / Pest Control, Biological / Pests / Planting / Plants, Genetically Modified / Populations / Refuges / Spodoptera frugiperda / Survival / Toxins / Vegetables / Zea mays / Zea mays - genetics / Zea mays - metabolism / Zea mays - microbiology