Journal of Insect Science (2006) 6 (46), 62-63

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B.E. Tabashnik, J.A. Fabrick, S. Henderson, R. Biggs, C. Yafuso, M. Nyboer, N. Manhardt, L. Coughlin, Y. Carrière, T.J. Dennehy and S. Morin (2006)
DNA screening reveals resistance remains rare in pink bollworm after a decade of exposure to Bt cotton
Journal of Insect Science 6 (46), 62-63
in M. Adams et al. [editors] Abstracts of the Fifth International Symposium on Molecular Insect Science (May 20-24, 2006, Tucson, Arizona USA), 76 pp.
Abstract: Transgenic crops producing Bacillus thuringiensis (Bt) toxins reduce reliance on insecticides, but evolution of resistance by pests could cut short their usefulness. Pink bollworm (Pectinophora gossypiella) is a major lepidopteran pest that has experienced selection for resistance to Cry1Ac, the toxin in Bt cotton, in Arizona since 1996. In laboratory-selected strains, resistance to Cry1Ac and survival on Bt cotton are linked with three recessive mutations in the gene encoding a cadherin protein that binds Cry1Ac. Each of the three resistant alleles has a deletion upstream of the putative Cry1Ac-binding region of cadherin protein. We developed a PCR-based method for detecting each of the three resistant alleles. Screening of DNA from >5,500 field-collected insects from 58 cotton fields detected no resistant alleles. Bioassays and field efficacy tests confirm that resistance to Cry1Ac remains rare in pink bollworm after a decade of widespread exposure to Bt cotton. A synthesis of experimental and modeling results suggests that key factors delaying pink bollworm resistance to Bt cotton are refuges of cotton without Bt toxin, recessive inheritance of resistance, incomplete resistance, and fitness costs associated with resistance.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Bruce E. Tabashnik, Yves Carriere, Jeff A. Fabrick

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


Pest and/or beneficial records:

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


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)