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Whitefly Bemisia tabaci (Gennadius) is an important pest of cotton in India. The study of taxonomic diversity and its distribution on cotton is lacking. Such studies are necessary to identify the genetic groups of B. tabaci and its distribution on cotton in India. The proper identification of genetic groups and their distribution, which, ultimately, can lead to the timely development and utilization of management practices. The current study was undertaken to explore the genetic diversity and phylogeographic structure of B. tabaci from all the three major cotton growing zones representing different agro-climatic conditions of India. 290 partial mitochondrial Cytochrome Oxidase I (mt COI) sequences of whitefly population of six major cotton-growing states covering 22 districts were used in the analysis. Phylogenetic analysis revealed the presence of two monophyletic clades, Asia I and Asia II1 genetic groups represents South-Central India and North India respectively. Asia II1 is found more predominately distributed in the cotton leaf curl virus (CLCuV) disease-prone north Indian cotton-growing states. Higher genetic divergence (16.8–19.2%) was observed between the populations of Asia I and Asia II1 genetic group. Genetic differentiation analysis confirmed the phylogeographic structure of B. tabaci as isolated by distance. Our results in mapping the distribution of genetic groups in cotton ecosystems paved the way for the further studies and formulation of area-wide management practices for cotton whitely in India. [ABSTRACT FROM AUTHOR]

The insecticidal and phytotoxicity activities of oils from castor (Ricinus communis), pongamia (Pongamia glabra), sesame (Sesamum indicum), neem (Azadirachta indica) and neem based formulations in combination with a detergent Powder as a surfactants (0.1%) were studied against adults of Bemisia tabaci at their peak activity period during 2016–17 and 2017–18 seasons under laboratory and field conditions. Among the oils, castor oil caused a reduction of whitefly populations by 55.4 & 64.2 and 40.5 & 42.8% under laboratory and field conditions, respectively during both the years, pongamia oil 58.4 & 51.7 and 44.9 & 39.2%, sesame oil 45.5 & 56.4 and 30.8 & 36.9%. Neem oil and its formulated products were reported to be comparatively less effective in reduction of whitefly population after chemical treatments i.e. difenthiauron 50 WP (76.2 & 81.5 and 63.5 & 55.2% under laboratory and field conditions, respectively). Phytotoxicity observed after application of recommended doses of castor, pongamia, sesame and neem oil and its formulated products did not cause any problem on tender cotton leaves. The detergent based solutions were difficult to mix and oily layers appeared after mixing, hence mixing the oils and detergent solutions with sticker Triton-X-100 @1.0 ml/l is more effective and easy to apply on cotton plants. [ABSTRACT FROM AUTHOR]