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Article
Effects of four nematode species on fitness costs of pink bollworm resistance to Bacillus thuringiensis toxin Cry1Ac
Journal of Economic Entomology
  • Eugene R. Hannon, University of Arizona
  • Mark S. Sisterson, United States Department of Agriculture
  • S. Patricia Stock, University of Arizona
  • Yves Carriere, University of Arizona
  • Bruce E. Tabashnik, University of Arizona
  • Aaron J. Gassmann, Iowa State University
Document Type
Article
Publication Date
10-1-2010
DOI
10.1603/EC10087
Abstract

Evolution of resistance by pests can reduce the efficacy of transgenic crops that produce insecticidal toxins from the bacterium Bacillus thuringiensis Berliner (Bt). In conjunction with refuges of non-Bt host plants, fitness costs can delay the evolution of resistance. Furthermore, fitness costs often vary with ecological conditions, suggesting that agricultural landscapes can be manipulated to magnify fitness costs and thereby prolong the efficacy of Bt crops. In the current study, we tested the effects of four species of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) on the magnitude and dominance of fitness costs of resistance to Bt toxin CrylAc in pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae). For more than a decade, field populations of pink bollworm in the United States have remained susceptible to Bt cotton Gossypium hirsutum L. producing CrylAc; however, we used laboratory strains that had a mixture of susceptible and resistant individuals. In laboratory experiments, dominant fitness costs were imposed by the nematodeSteinernema riobrave Cabanillas, Poinar, and Raulston but no fitness costs were imposed bySteinernema carpocapsae Weiser, Steinernema sp. (ML18 strain), or Heterorhabditis sonorensis Stock, Rivera-Orduño, and Flores-Lara. In computer simulations, evolution of resistance to CrylAc by pink bollworm was substantially delayed by treating some non-Bt cotton refuge fields with nematodes that imposed a dominant fitness cost, similar to the cost observed in laboratory experiments with S. riobrave. Based on the results here and in related studies, we conclude that entomopathogenic nematodes could bolster insect resistance management, but the success of this approach will depend on selecting the appropriate species of nematode and environment, as fitness costs were magnified by only two of five species evaluated and also depended on environmental factors.

Comments

This article is from Journal of Economic Entomology, 103 (2010): 1821, doi:10.1603/EC10087.

Rights
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
Language
en
Date Available
2014-09-26
File Format
application/pdf
Citation Information
Eugene R. Hannon, Mark S. Sisterson, S. Patricia Stock, Yves Carriere, et al.. "Effects of four nematode species on fitness costs of pink bollworm resistance to Bacillus thuringiensis toxin Cry1Ac" Journal of Economic Entomology Vol. 103 Iss. 5 (2010) p. 1821 - 1831
Available at: http://works.bepress.com/aaron_gassmann/38/