Pest Management Science (2018) 74, 2496-2503

Yves Carrière, Jennifer L. Williams, David W. Crowder and Bruce E. Tabashnik (2018)
Genotype-specific fitness cost of resistance to Bt toxin Cry1Ac in pink bollworm
Pest Management Science 74 (11), 2496-2503
Abstract:
BACKGROUND
To improve resistance management strategies for Bacillus thuringiensis (Bt) crops, a better understanding of the relative fitness of pest genotypes with resistance alleles in the absence of Bt toxins is needed. Here, we evaluated the impact of costs of resistance to Bt toxin Cry1Ac on the relative fitness of specific pink bollworm (Pectinophora gossypiella) genotypes. We created two heterogeneous strains with an intermediate frequency of mutant cadherin alleles linked with resistance to Cry1Ac, reared the strains on diet without Bt and tracked the decline in frequency of resistant genotypes for 15–30 generations using polymerase chain reaction amplification. We used a population genetics model and sensitivity analyses to estimate the relative fitness of resistant genotypes.
RESULTS
Costs were completely recessive in one strain and almost completely recessive in the other. Estimates of the decline in relative fitness of the resistant homozygotes fed on a diet without Bt were 14–22% in one strain and 21–36% in the other.
CONCLUSION
Our genotype-specific cost estimates and the results of studies discussed herein indicate that costs associated with resistance to Bt are often large enough to significantly delay the evolution of resistance to pyramided Bt crops in pests with recessive inheritance of resistance.
(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): Yves Carriere, Bruce E. Tabashnik, David W. Crowder

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

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pectinophora gossypiella
Bacillus thuringiensis Cry1A-toxin (entomopathogen)	Pectinophora gossypiella