Journal of Economic Entomology (2006) 99, 920-926

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Aaron J. Gassmann, S. Patricia Stock, Yves Carrière and Bruce E. Tabashnik (2006)
Effect of entomopathogenic nematodes on the fitness cost of resistance to Bt toxin Cry1Ac in pink bollworm (Lepidoptera: Gelechiidae)
Journal of Economic Entomology 99 (3), 920-926
Abstract: The widespread use of crop plants genetically engineered to produce toxins from the bacterium Bacillus thuringiensis (Bt) imposes selection on insect populations to evolve resistance. The pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), is a major pest of cotton in the southwestern United States that is currently controlled with transgenic cotton that produces Bt toxin Cry1Ac. Previously reported theoretical work suggests that, in conjunction with a high dose/refuge strategy, fitness costs of Bt resistance can slow or prevent the evolution of resistance. We report here that the entomopathogenic nematode Steinernema riobrave (Rhabditida: Steinernematidae) increased the fitness cost of resistance to Cry1Ac in P. gossypiella. Mortality of P. gossypiella from fourth instar to adult eclosion was significantly higher for a Bt-resistant strain than a susceptible strain in tests with two to 14 infective juveniles of S. riobrave per larva, but it did not differ between strains when nematodes were absent. Nematodes established in P. gossypiella larvae at all concentrations tested, and nematode reproduction in infected P. gossypiella larvae occurred at nematode concentrations of four to 14 infective juveniles per larva. Our results suggest that incorporation of entomopathogenic nematodes into an integrated resistance management strategy could help to delay pest resistance to Bt toxins.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Aaron J. Gassmann, Yves Carriere, Bruce E. Tabashnik, S. Patricia Stock

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
application technology

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Pectinophora gossypiella Cotton (Gossypium) U.S.A. (SW)
Steinernema riobrave/Xenorhabdus cabanillasii (entomopathogen) Pectinophora gossypiella Cotton (Gossypium) U.S.A. (SW)
Bacillus thuringiensis genes in crops (entomopathogen) Pectinophora gossypiella Cotton (Gossypium) U.S.A. (SW)
Bacillus thuringiensis Cry1A-toxin (entomopathogen) Pectinophora gossypiella Cotton (Gossypium) U.S.A. (SW)