Journal of Economic Entomology (2002) 95, 1018-1026

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Bruce E. Tabashnik, Yong-Biao Liu, Timothy J. Dennehy, Maria A. Sims, Mark S. Sisterson, Robert W. Biggs and Yves Carrière (2002)
Inheritance of resistance to Bt toxin Cry1Ac in a field-derived strain of pink bollworm (Lepidoptera: Gelechiidae)
Journal of Economic Entomology 95 (5), 1018-1026
Abstract: Laboratory selection with Cry1Ac, the Bacillus thuringiensis (Bt) toxin in transgenic cotton, initially produced 300-fold resistance in a field-derived strain of pink bollworm, Pectinophora gossypiella (Saunders), a major cotton pest. After additional selection increased resistance to 3,100-fold, we tested the offspring of various crosses to determine the mode of inheritance of resistance to Cry1Ac. The progeny of reciprocal F1 crosses (resistant male x susceptible female and vice versa) responded alike in bioassays, indicating autosomal inheritance. Consistent with earlier findings, resistance was recessive at a high concentration of Cry1Ac. However, the dominance of resistance increased as the concentration of Cry1Ac decreased. Analysis of survival and growth of progeny from backcrosses (F1 x resistant strain) suggest that resistance was controlled primarily by one or a few major loci. The progression of resistance from 300- to 3,100-fold rules out the simplest model with one locus and two alleles. Overall the patterns observed can be explained by either a single resistance gene with three or more alleles or by more than one resistance gene. The pink bollworm resistance to Cry1Ac described here fits "mode 1" resistance, the most common type of resistance to Cry1A toxins in Lepidoptera.
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Database assignments for author(s): Bruce E. Tabashnik, Yves Carriere, Yong-Biao Liu

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
pesticide resistance of pest
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)