Chandi, Anureet KaurSavinderjeet Singh2018-09-112018-09-112018http://krishikosh.egranth.ac.in/handle/1/5810072749Pyriproxyfen, a pyridine based juvenile hormone analogue with mode of action different from the conventional insecticides, was evaluated for its physiological influences on nymphs and adults of whitefly, Bemisia tabaci (Gennadius) during 2016 and 2017. Various toxicity values i.e. LC30 (0.020, 0.021%) and LC50 (0.043, 0.048%) for first instar nymphs; LC30 (0.026, 0.029%) and LC50 (0.055, 0.060%) for fourth instar nymphs; LC30 (0.031, 0.034%) and LC50 (0.061, 0.069%) for adults were worked out by employing standard methods of bioassay. Significant increase in 50 per cent red-eyed nymph formation (14.00 and 10.50 against 7.40 and 5.90 days in control) and nymphal period (15.20 and 12.20 against 8.50 and 6.80 days in control) was registered under influence of pyriproxyfen. In contrast, when first instar nymphs were treated with pyriproxyfen, there was reduction in adult emergence (49.78 and 50.19 against 76.05 and 79.38% in control); adult longevity (3.70 and 4.40 against 5.80 and 7.40 days in the control); oviposition period (1.70 and 1.90 against 3.10 and 3.20 days in control); fecundity (10.80 and 11.83 against 19.70 and 20.85 eggs in control) and egg hatching (20.74 and 21.82 against 60.11 and 62.28% in control). Inhibition of fecundity (7.73 and 8.44 in treated; 15.48 and 15.83 in control) and curtailed egg hatching (24.56 and 26.90 in treated; 65.10 and 67.70 in control) was ascertained. Mortality of first instar nymphs (47.72 and 45.85%) on lower surface of cotton leaves indicates pronounced translaminar effect in both the years. Significant reduction in the total amino acids, increased level of total sugars and phenols of treated cotton plants could be correlated with lesser whitefly population density. Hence, pyriproxyfen, given to its several lethal and sublethal influences can be used as an effective tool for management of B. tabaci.ennullThesis