Journal of Economic Entomology (2004) 97, 721-726

Bruce E. Tabashnik, Yong-Biao Liu, Devika C. Unnithan, Yves Carrière, Timothy J. Dennehy and Shai Morin (2004)
Shared genetic basis of resistance to Bt toxin Cry1Ac in independent strains of pink bollworm
Journal of Economic Entomology 97 (3), 721-726
Abstract: Classical and molecular genetic analyses show that two independently derived resistant strains of pink bollworm, Pectinophora gossypiella (Saunders), share a genetic locus at which three mutant alleles confer resistance to Bacillus thuringiensis (Bt) toxin Cry1Ac. One laboratory-selected resistant strain (AZP-R) was derived from individuals collected in 1997 from 10 Arizona cotton fields, whereas the other (APHIS-98R) was derived from a long-term susceptible laboratory strain. Both strains were previously reported to show traits of "mode 1" resistance, the most common type of lepidopteran resistance to Cry1A toxins. Inheritance of resistance to a diagnostic concentration of Cry1Ac (10 µg per gram of diet) was recessive in both strains. In interstrain complementation tests for allelism, F₁ progeny from crosses between the two strains were resistant to the diagnostic concentration of Cry1Ac. These results indicate that a major resistance locus is shared by the two strains. Analysis of DNA from the pink bollworm cadherin gene (BtR) using allele-specific polymerase chain reaction (PCR) tests showed that the previously identified resistance alleles (r1, r2, and r3) occurred in both strains, but their frequencies differed between strains. In conjunction with previous findings, the results reported here suggest that PCR-based detection of the three known cadherin resistance alleles might be useful for monitoring resistance to Cry1Ac-producing Bt cotton in field populations of pink bollworm.
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Full text of article
Database assignments for author(s): Bruce E. Tabashnik, Yves Carriere, Yong-Biao Liu

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	Cotton (Gossypium)	U.S.A. (SW)
Bacillus thuringiensis Cry1A-toxin (entomopathogen)	Pectinophora gossypiella