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Transgenic Bt cotton is effective to a high degree of, with respect to target lepidoptran bollworms, however sucking pests especially whitefly posed a serious issues in absence of bollworm in genetically modified (GM) crops. Therefore, to understand the efficacy of various biorational compounds against whitefly under non-weedy as well as weedy field conditions, studies on whitefly carried out during kharif 2018, to know the changes in number of whitefly adults as well as nymphs. Transgenic hybrid cotton variety RCH 650 was sown with a spacing of 100×45 cm and replicated four times in both non-weedy and weedy habitat. Although, standard check Dimethoate 30 EC proved it’s efficacy after first and second spray in cotton crop against whitefly. Not with standing, after the application of biorational first time as spray in 29th Standard Meteoroloical Week (SMW), Nimbecidine 300 ppm was admitted as most effective in non-weedy (66.76 and 60.65% mean mortality in whitefly adult and nymph, respectively) as well as in weedy habitat that caused 56.77 and 55.54% mean mortality in adult and nymph, respectively over a period of seven days after application. Entomopathogenic fungi Verticillium lecanii found better to control whitefly adults (42.06 and 40.63%), while Metarhizium anisopliae (42.39 and 36.01%) found more effective for nymphal mortality in non-weedy as well as in weedy habitat. One and same pattern of efficacy of biorational was reconstructed against whitefly again after second application of biorational in all the treatment selected to test against whitefly.
Kumar et al. (Sat,) studied this question.