Journal of Economic Entomology (2008) 101, 504-514

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Shannon Heuberger, Christa Ellers-Kirk, Christine Yafuso, Aaron J. Gassmann, Bruce E. Tabashnik, Timothy J. Dennehy and Yves Carrière (2008)
Effects of refuge contamination by transgenes on Bt resistance in pink bollworm (Lepidoptera: Gelechiidae)
Journal of Economic Entomology 101 (2), 504-514
Abstract: Refuges of non-Bacillus thuringiensis (Bt) cotton, Gossypium hirsutum L., are used to delay Bt resistance in pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), a pest that eats cotton seeds. Contamination of refuges by Bt transgenes could reduce the efficacy of this strategy. Previously, three types of contamination were identified in refuges: 1) homozygous Bt cotton plants, with 100% of their seeds producing the Bt toxin Cry1Ac; 2) hemizygous Bt plants with 70-80% of their seeds producing Cry1Ac; and 3) non-Bt plants that outcrossed with Bt plants, resulting in bolls with Cry1Ac in 12-17% of their seeds. Here, we used laboratory bioassays to examine the effects of Bt contamination on feeding behavior and survival of pink bollworm that were resistant (rr), susceptible (ss), or heterozygous for resistance (rs) to Cry1Ac. In choice tests, rr and rs larvae did not differ from ss in preference for non-Bt versus Bt seeds. Survival of rr and rs also did not differ from ss on artificial outcrossed bolls (a mixture of 20% Bt and 80% non-Bt cotton seeds). On artificial hemizygous Bt bolls (70% Bt seeds) and homozygous Bt bolls (100% Bt seeds), rr had higher survival than ss, although rs and ss did not differ. In a simulation model, levels of refuge contamination observed in the field had negligible effects on resistance evolution in pink bollworm. However, in hypothetical simulations where contamination conferred a selective advantage to rs over ss individuals in refuges, resistance evolution was accelerated.
(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): Shannon Heuberger, Aaron J. Gassmann, Yves Carriere, Bruce E. Tabashnik

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
resistance/tolerance/defence of host


Pest and/or beneficial records:

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


Pectinophora gossypiella Cotton (Gossypium)
Bacillus thuringiensis genes in crops (entomopathogen) Pectinophora gossypiella Cotton (Gossypium)
Bacillus thuringiensis Cry1A-toxin (entomopathogen) Pectinophora gossypiella Cotton (Gossypium)