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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY BASED PEST MANAGEMENT IN MODERN CROPPING SYSTEMS

Location: North Central Agricultural Research Laboratory

Title: Assessment of fitness costs in Cry3Bb1 resistant and susceptible western corn rootworm (Coleoptera: Chrysomelidae) laboratory colonies

Authors
item Oswald, Kenneth -
item French, Bryan
item Nielson, Chad
item Bagley, Mark -

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 28, 2011
Publication Date: February 1, 2012
Citation: Oswald, K., French, B.W., Nielson, C.N., Bagley, M. 2012. Assessment of fitness costs in Cry3Bb1 resistant and susceptible western corn rootworm (Coleoptera: Chrysomelidae) laboratory colonies. Journal of Applied Entomology. 136:730-740. DOI: 10.1111/j.1439-0418.2012.01704.x.

Interpretive Summary: Corn production in the United States is dominated by plants genetically modified with genes from Bacillus thuringiensis (Bt). Varieties of Bt maize expressing toxins that specifically target corn rootworms have proven highly efficacious. However, development of resistance to Bt corn, especially among western corn rootworm populations, poses a significant threat to the future viability of this pest control biotechnology. The high dose, structured refuge insect resistance management strategy implemented in the United States for Bt corn assumes no fitness costs of Bt resistance, even though these have been shown to strongly influence the dynamics of Bt resistance within numerous agricultural pest species. To investigate the effects of Bt resistance on fitness components of western corn rootworm, we compared survivorship, fecundity, and viability of five Bt resistant laboratory lines reared on MON863 (YieldGard Rootworm®), a variety of Bt corn that produces a crystalline protein toxin called Cry3Bb1, and its non-Bt isoline. Analysis of performance on the isoline corn demonstrated no fitness costs associated with Bt resistance. Resistant lines reared on Bt corn displayed higher fecundity compared to those reared on isoline. Emergence of resistant lines reared on MON863 was not significantly delayed compared to resistant and control lines reared on the isoline, but delayed emergence of ~ 4-6 days was observed for the susceptible line reared on MON863. These data will be valuable for formulating improved insect resistance management strategies for a principal agricultural pest of corn.

Technical Abstract: Maize production in the United States is dominated by plants genetically modified with transgenes from Bacillus thuringiensis (Bt). Varieties of Bt maize expressing Cry3Bb d endotoxins that specifically target corn rootworms (genus Diabrotica) have proven highly efficacious. However, development of resistance to Bt maize, especially among western corn rootworm (Diabrotica virgifera virgifera) populations, poses a significant threat to the future viability of this pest control biotechnology. The high dose, structured refuge insect resistance management strategy implemented in the United States for Bt maize assumes no fitness costs of Bt resistance, even though these have been shown to strongly influence the dynamics of Bt resistance within numerous agricultural pest species. To investigate the effects of Bt resistance on fitness components of western corn rootworm, we compared survivorship, fecundity, and viability of five Bt resistant laboratory lines reared on MON863 (YieldGard Rootworm®), a variety of Bt maize that expresses Cry3Bb1 d endotoxin, and its nontransgenic isoline. Analysis of performance on the isoline maize demonstrated no fitness costs associated with Bt resistance. Resistant lines reared on Bt maize displayed higher fecundity compared to those reared on isoline. Emergence of resistant lines reared on MON863 was not significantly delayed compared to resistant and control lines reared on the isoline, but delayed emergence of ~ 4-6 days was observed for the susceptible line reared on MON863. These data will be valuable for formulating improved insect resistance management strategies for a principal agricultural pest of maize.

Last Modified: 8/2/2014
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