Seasonal incidence of mustard aphid, Lipaphis erysimi kaltenbach on Rabi mustard crop

The maximum population of Lipaphis erysimi were recorded in 8th standard week (80.00) of February on mustard crop when average atmospheric temperature was 21.4°C, relative humidity 66% and rainfall 6.0 mm. The population was slowly decline and reached zero in13 standard week of month of March when average maximum temperature 26.90 °C, average maximum relative humidity 46.5%, average maximum rainfall 3.0 mm. The aphid population showed a nonsignificant negative co-relation with maximum temperature while minimum temperature relative humidity rainfall showed a non-significant positive correlation.