Department of Entomology, C.S.K. Himachal Pradesh Krishi Vishvavidyalaya, Palampur-176 062, H.P., (India).
The peak population of Lipaphis erysimi and Brevicoryne brassicae was recorded during second week of March with maximum and minimum temperature of 22.5°C and 10.3°C respectively. The mean relative humidity was 36% and no rainfall was recorded during the same period. The maximum population of Myzus persicae was observed during last week of January with maximum temperature of 4°C, relative humidity 58% and no rainfall. The population of L. erysimi registered a negative correlation with maximum and minimum temperature as well as rainfall whereas B. brassicae showed a positive but low correlation with temperature. M. presicae registered negative but significant correlation with temperature and relative humidity.
