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Characterization of three bacterial symbionts (BC1, BC2 and BC3) of fruit fly Bactrocera tau including morphological, biochemical and 16S rDNA (rrs gene) analysis was done to determine their taxonomic position. Morphological and biochemical characterization placed two bacteria (BC1, Klebsiella oxytoca and BC2, Pantoea agglomerans) into family Enterobacteriaceae and the third one (BC3, Staphylococcus sp.) into family Staphylococcaceae. 16S rDNA gene sequence comparison with the available NCBI database sequences further confirmed the characterizations of bacterial symbionts. Molecular phylogeny of Klebsiella oxytoca and Pantoea agglomerans closely related to the other free living enterobacterial members with 74 to 93% sequence homology (genetic distance 0.000 to 0.085); however, they showed only 74 to 87% similarity with other insect symbionts (genetic distance 0.090 to 0.121). Staphylococcus sp. showed 94% sequence homology with other members of family Staphylococcaceae with the genetic distance of 0.013. Population of these symbionts in adult fruit flies increased exponentially up to the 10th day of adult emergence and thereafter it became almost constant.

Population genetic structure of melon fly analysed with mitochondrial cytochrome oxidase I gene suggested that melon fly populations across the globe is homogeneous with non-significant variation of 0.000-0.003 base substitutions per site. Test isolates representing various geographic situations across the world were placed in 26 mitochondrial haplotypes based on variations associated with a maximum of three mutational steps and the predominant haplotype i.e. H1 was present in all melon fly populations except Hawaiian population. Evolution of mtCOI gene suggested that the fly could have originated some 0.4 million years ago. The present study also indicated that the B. cucurbitae population expansion is an event of post Pleistocene warm climatic conditions with small number of founder population. The invasion of B. cucurbitae in Hawaii was associated with the large population size and the global presence of the fly is associated with human mediated dispersal. The very low genetic variation suggested that the fly management might be possible by large scale sterile insect techniques programme.

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A granulosis virus strain infecting Pieris brassicae (PbGV) was isolated from the dry temperate region of northwestern Himalayas as a potential microbial agent for its management. The effect of different botanicals (having insecticidal action against P. brassicae) on the bioefficacy of PbGV was evaluated under laboratory conditions using leaf disc bioassays on cabbage for improving the insecticidal performance of the PbGV. The synergistic action of different botanical extracts was evident in terms of reduction in LC 50 values against different botanical extracts. Among different extracts, petroleum-ether extract of neem seed kernel (NSK) when combined with PbGV resulted in maximum reduction of LC 50 value (4.39×10 2 occlusion bodies [OBs] ml −1 ) followed by methanolic extract (7.38×10 2 OBs ml −1 ) and aqueous extract (9.36×10 3 OBs ml −1 ) as compared with PbGV alone (1.85×10 4 OBs ml −1 ) for 2nd instar larvae of the test insect. These trends were found analogous in cases of 3rd and 4th instars of P. brassicae with different solvent extracts of NSK. The other botanicals evaluated, viz., Eupatorium and Artemesia, also resulted in reduction of LC 50 values for 2nd, 3rd and 4th instars as compared with PbGV alone when different extracts were combined with virus for bioassays. The studies suggest that the PbGV in combination with botanical pesticides could be more useful as a bio-pesticide against cabbage butterfly (P. brassicae) in IPM programs.