Population fluctuation of Lipaphis erysimi (Kalt) on mustard crop in Western U. P.

The field experiment was conducted in randomized block design with three replications of eight treatments for a crop season of the year i.e. “Rabi 2015-16” at entomological research block of crop research centre, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut - 250110 (U.P.), India. In extensive during study, the population of Liphaphis erysimi (Kalt), on mustard crop. The data showed that population of L. erysimi appeared in last week of December i.e. 51st standard week and continued till last week of March i.e. 13th standard week. The pest populations recorded as number of aphids per 10 cm main apical shoot. The aphid population was low during the 51th standard week of the December to 3st week of January which varied between 2.50 to 7.50 aphids. The pest population increased from third week of January and reached its peak during 7th standard week i.e. third week of February. During this period the weather parameters like mean temperature and relative humidity ranged from 12.10 0C to 16.20 0C and 80.2 to 71.70 per cent, respectively. The pest population declined thereafter and varied from 18.50 to 65.25 aphids/10cm main apical shoot. During this period mean temperature and relative humidity ranged from 12.10 0C to 16.20 0C and 81.20 to 71.70 per cent, respectively. The population of aphids suddenly decreased in the last week of March (12th standard week) and last week of March (13th standard week).