Effect of abiotic factors on population of mustard aphid Lipaphis erysimi (Kalt.) under mustard agro-ecosystem

The occurrence of aphid populations started during the 2^nd week of January and attained its peaked during the 2^nd week of February, 2018 with 117.96 aphid/10 cm central shoots. The temperature (maximum, minimum) on the observation day was 24.1 and 10.65°C, 83.25% and 48.25% was maximum and minimum relative humidity respectively. Thereafter, the population decline more or less gradually being minimum 1st week of March 2018 recording 0.06 aphid/10 cm central shoots. The correlation between aphid population and temperature (maximum, minimum) showed a negative correlation with ‘r’ value of-0.4288 and-0.2741, respectively. Whereas a positive correlation with morning relative humidity, a negative correlation with evening relative humidity. The correlation between aphid population and temperature, relative humidity was found statistically non-significant.