Bio-efficacy of some newer insecticides against mustard aphid, Lipaphis erysimi (Kalt.) and their offect on Natural enemies in rapeseed mustard

Abstract

An investigation was carried out to study the "Bio-efficacy of some newer insecticides against mustard aphid, Lipaphis erysimi (Kalt.) and their effect on natural enemies in rapeseed-mustard" in randomized block design with three replications at Crop Research Centre of Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut during Rabi 2010-11. During the crop season, twelve insect species were found attacking the rapeseed-mustard at different crop growth stages. Of these, mustard aphid, Lipaphis erysimi (Kalt.) and cabbage butterfly, Pieris brassicae (Linn.) were recorded as major pests. The incidence of L. erysimi was recorded first on the fourth week of December and reached to its peak (65.00 aphids I 10 em main apical shoot) during fourth week of January when average temperature and relative humidity were 13.49 °C and 59.78 per cent, respectively. Incidence of L. erysimi was negatively correlated with all the weather parameters except rainfall which showed positive correlation. Efficacy of different insecticides viz., acetamiprid, imidacloprid, dimethoate, acephate, thiamethoxam, endosulfan and neemarin tested against L. erysimi revealed that thiamethoxam 25°/o WDG @100 g/ha was found most effective treatment in reducing the population of aphids followed by imidacloprid 17.8% SL @ 150 ml/ha. The neemarin 1500 PPM @ 3000 ml/ha was recorded less effective. Among conventional insecticides dimethoate 30% EC @ 1 000 ml/ha was found more effective than endosulfan 35% EC @ 1200 ml/ha. The higher yield was obtained from thiamethoxam whereas, highest cost benefit ratio is obtained from acetamiprid. lmidacloprid was found most safer to coccinellid population followed by thiamethoxam at all observational interval.