Kumar, ManojJha, Sudeepa Kumari2018-02-072018-02-072017http://krishikosh.egranth.ac.in/handle/1/5810040514Population dynamics of whitefly, Bemisia tabaci and its management through use of insecticides - profenophos @ 500 g a.i. ha-1, imidacloprid @ 20 g a.i. ha-1, cypermethrin @ 25 g a.i. ha-1, indoxacarb @ 50 g a.i. ha-1, profenophos (40 %) + cypermethrin (4%) @ 440 g a.i. ha-1, neem seed kernel extract (NSKE) 5 %, neem oil 2 %, tobacco decoction 5 % and yam bean seed extract (YBSE) 5 % in tomato variety ‘Avinash – 2’ was studied at Vegetable Research Farm of Dr. Rajendra Prasad Central Agricultural University, Pusa during Rabi 2016-17. Peak population (42.4 per three leaves) of whitefly was observed on 70th day after transplanting. Temperature (max. and min.) and sunshine (hrs) had a negative significant correlation, while morning and evening relative humidity had a positive significant correlation but wind speed had non- significant positive correlation. The correlation coefficient (r) was computed for max. Temperature (-0.481), min. temperature (-0.483), morning relative humidity (0.514), evening relative humidity (0.483), wind speed (0.007) and sunshine hrs (-0.641), respectively. The weather parameters were found to contribute around 55.70 per cent impact on population of Bemisia tabaci when acted together (R2 = 0.5570). The mean per cent reduction in whitefly population over control after first, fifth and seventh day of 1st, 2nd and 3rd spray of insecticides was maximum in imidacloprid @ 20 g a.i. ha-1 (47.41 %, 81.03 % and 88.14 %, respectively) followed by profenophos 40 % + cypermethrin 4% @ 440 g a.i. ha-1 (42.20, 77.38 and 85.93 %, respectively). All the insecticidal treatments proved profitable over control and increase in yield varied from the maximum of 90 q ha-1 in imidacloprid (20 g a.i. ha-1) to the minimum of 48 q ha-1 in tobacco decoction 5 %. The benefit cost ratio was highest in imidacloprid @ 20 g a.i. ha-1 (22.69: 1) followed by cypermethrin @ 25 g a.i. ha-1 (17.21:1) and lowest in YBSE 5% (1.53: 1).ennullThesis