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Pink bollworm (PBW),Pectinophora gossypiellais one of the most destructive pest’s globally inflicting huge economic losses in cotton even during later stages of crop growth. In the present investigation, the population genetic structure, distribution, and genetic diversity ofP. gossypiellain cotton growing zones of India using partial mitochondrial DNA cytochrome oxidase-I (COI) gene was addressed. The overall haplotype (Hd),number of nucleotide differences (K), and nucleotide diversity (π) were 0.3028, 0.327, and 0.00047, respectively which suggest that entire population exhibited low level of genetic diversity. Zone-wise clustering of population revealed that central zone recorded low level ofHd(0.2730) as compared to north (0.3619) and south (0.3028) zones. The most common haplotype (H1) reported in all 19 locations could be proposed as ancestral/original haplotype. This haplotype with one mutational step formed star-like phylogeny connected with 11 other haplotypes. The phylogenetic relationship studies revealed that most haplotypes of populations are closely related to each other. Haplotype 5 was exclusively present in Dharwad (South zone) shared with populations of Hanumangarh and Bathinda (North zone). The result indicated that there is no isolation by distance effect among the Indian populations of PBW. The present study reports a low genetic diversity among PBW populations of India and H1, as ancestral haplotype from which other haplotypes have evolved suggests that the migration and dispersal over long distance and invasiveness are major factors. [ABSTRACT FROM PUBLISHER]

The baseline toxicity of Cry1A δ-endotoxins (derived from Bacillus thruringiensis (Kurstaki)) on field populations of the cotton bollworm, Helicoverpa armigera (Hub.), was determined through log dose probit analysis. All the three Cry1A proteins were found to be toxic to the bollworm larvae. Cry1Ac was found to be the most toxic followed by Cry1Aa andCry1Ab. LC[sub 50] values ranged from 0.07 to 0.99 μg/ml(14- fold) for Cry1Aa, 0.69 to 9.94 μg/ml (14-fold) for Cry1Ab and 0.01 to 0.67 μg/ml of diet (67-fold) for Cry1Ac. The LC[sub 50] values deduced from the cumulative log dose probit response of the data pooled from all assays, were 0.62 μg/ml for Cry1Aa, 4.43 μg/ml for Cry1Ab and 0.100 μg/ml of diet for Cry1Ac. The respective LC[sub 50] values represent the baseline susceptibility indices for resistance monitoring through the conventional log dose probit assays. The LC[sub 99] values derived from the cumulative data were 515 μg/ml for Cry1Aa, 13385 μg/ml for Cry1Ab and 75 μg/ml of diet for Cry1Ac. These values represent the diagnostic doses for routine monitoring of resistance to the respective toxins through discriminating dose assays after the introduction of Bt transgenic crops. [ABSTRACT FROM AUTHOR]