author(s)
Matangi Mishra and U Mukherjee

abstract
Among the natural enemies of mustard aphid, Coccinella septempunctata and Syrphid flies are dominating. During the experimental year 2017-18, it was observed that the appearance of ladybird beetle that is Coccinella septempunctata was 0.30 as seen in the fourth standard week of observation when the aphid population was growing high and it was equal in comparison with the Syrphid fly (0.30). The correlation of ladybird beetle was -0.012 with the maximum temperature while with the minimum temperature it was -0.162 and Syrphid fly was found -0.180 with the maximum temperature and -0.176 with the minimum temperature (negative and non- significant). There was not any correlation with the rainfall as there was no rain during that period. The correlation of relative humidity in ladybird beetle was 0.251 at 0700 hours and 0.207 at 1400 hours. In case of Syrphid fly, the relative humidity was -0.633 and non-significant at 0700 hours while at 1400 hours it was 0.453 and non-significant. In the second experimental year, 2018-19, the trend of population of both the natural enemies was of same pattern. The population of ladybird beetle was found 0.20 in the fourth standard week and its peak was 1.00 in the eighth standard week. The population of Coccinella septempunctata was found 0.10 upto the tenth standard week and it became 0.00 after that. In case of Syrphid fly, the population initially was 0.20 in the fourth standard week. It was maximum 1.10 in seventh standard week and gradually it declined to 0.40 in the ninth standard week and became 0.20 in the tenth standard week.. In case of ladybird beetle it was -0.012 with the maximum temperature and -0.087 with the minimum temperatuire. The correlation with the relative humidity of ladybird beetle was found -0.515 that is non- significant at 0700 hours and at 1400 hours it was -0.081 that is non -significant too. In case of Syrphid fly the correlation with the maximum temperature was non-significant and negatively correlated that is -0.142 while with the minimum temperature it was -0.083 and non-significant. The rainfall was found non-significant in both the cases. The relative humidity at 0700 hr was -0.529 and at 1400 hr it was 0.453 in case of Syrphid fly and was found non -significant.