Journal of Pest Science (2007) 80, 175-181

P.S. Shanmugam, R. Balagurunathan, N. Sathiah and N.G.V. Rao (2007)
Inheritance and cross-resistance of Bacillus thuringiensis insecticidal crystal protein Cry1Ac resistance in cotton bollworm Helicoverpa armigera Hubner population from Tamil Nadu, India
Journal of Pest Science 80 (3), 175-181
Abstract: Cotton bollworm, Helicoverpa armigera Hubner selected for five generations with Bacillus thuringiensis insecticidal crystal protein Cry1Ac in the laboratory developed 12.98-fold resistance. Resistance and susceptible populations were mass crossed to study the dominance of resistance. The Cry1Ac-selected (BCR) population showed 5.8-fold resistance to Cry1Aa and 5.04-fold resistance to Cry1Ab. The degree of dominance (D) was 0.34 and 0.40 for the R × S and S × R hybrids, respectively, which indicates incomplete recessive character of Cry1Ac resistance in the population. The estimated realized heritability (h ²) and response quotient (Q) of resistance for Cry1Ac were 0.52 and 0.15, respectively. This indicated the lower phenotypic variation in the selected population. The resistance risk assessment based on h ² indicated that the resistance would increased tenfold after <9 generations for Cry1Ac in the resistant population. The results show the ability of H. armigera to develop resistance against Cry1Ac and cross-resistance to Cry1Aa and Cry1Ab.
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Link to article at publishers website
Database assignments for author(s): P.S. Shanmugam

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.
	Helicoverpa armigera		India
Bacillus thuringiensis Cry1A-toxin (entomopathogen)	Helicoverpa armigera		India