Population dynamics of mustard aphid (Lipaphis erysimi Kalt.) in terai agroclimatic region of West Bengal

2-year experiment established that the aphid population appeared on mustard (variety Binoy-B9) in the first standard week and reached a peak during the seventh standard week (3rd week of February). Subsequently, the aphid population was steadily reduced until the 10th Standard Week (2nd week of March) or the crop harvest. The minimum temperature and evening RH showed a significant negative correlation with the aphid population. All the other variables had a non-significant relationship. The R-value for regression between aphid population and weather parameters was 0.4973, representing that weather parameters contributed 49.37% of aphid population variance in 1st year and 58.39% in 2nd year.