ARS | Publication request: Greenhouse-selected resistance to Cry3Bb1-producing corn in three western corn rootworm populations

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 29, 2012
Publication Date: December 20, 2012
Citation: Meihls, L.N., Higdon, M.L., Elliersieck, M.R., Tabashnik, B.E., Hibbard, B.E. 2012. Greenhouse-selected resistance to Cry3Bb1-producing corn in three western corn rootworm populations. PLoS One. 7(12):e51055. Available http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0051055.

Interpretive Summary: The study and development of colonies of corn rootworms resistant to transgenic corn that carry an insecticide can help us understand how such resistance occurs and help us to slow resistance in current and future control measures. We have developed laboratory colonies of the western corn rootworm (WCR) that were derived from field populations collected in Kansas, Minnesota, and Wisconsin. Each population was reared on transgenic corn expressing the bacterial insecticidal protein Bt (containing the Cry3Bb1gene) or non-transgenic, control corn that has the same genetic background. We generated two types of WCR colonies: "selected” (from WCR from each population grown on transgenic corn) and “control” (from WCR from each population grown on control corn). Data collected from both greenhouse and the field studies demonstrated that “selected” colonies survived equally well on either transgenic or control corn plants and did similar damage to both. The control colonies survived significantly better on control corn than they did on transgenic corn. This data indicates that WCR rapidly develops resistance to the insecticidal protein Bt when reared on transgenic corn. This rapid evolution of resistance by WCR to Bt corn accentuates the importance of effective resistance management for this pest and will enable corn producers to develop improved management strategies.

Technical Abstract: Transgenic corn producing the Bacillus thuringiensis (Bt) toxin Cry3Bb1 has been useful for controlling western corn rootworm, Diabrotica virgifera virgifera LeConte, one of the most economically important crop pests in the United States. However, rapid evolution of resistance by this beetle to Bt corn producing Cry3Bb1 has been reported previously from the laboratory, greenhouse, and field. Here we selected in the greenhouse for resistance to Cry3Bb1 corn in three colonies of WCR derived from Kansas, Minnesota, and Wisconsin, respectively. Three generations of rearing on Cry3Bb1 corn significantly increased larval survival on Cry3Bb1 corn, resulting in similar survival in the greenhouse for selected colonies on Cry3Bb1 corn and isoline corn that does not produce Bt toxin. After four to seven generations of rearing on Cry3Bb1 corn, survival in the field on Cry3Bb1 corn relative to isoline corn more than doubled for selected colonies (72%) compared with unselected control colonies (33%). For selected colonies, survival in the field was significantly lower on Cry3Bb1 corn than on isoline corn. On isoline corn, most fitness components were similar for selected and control colonies, yet fecundity was significantly lower for selected than control colonies, indicating a fitness cost associated with resistance. The rapid evolution of resistance by western corn rootworm to Bt corn reported here and previously underlines the importance of effective resistance management for this pest.