Correlation between the Seasonal Incidence of Aphids and Coccinellids on the Indian Mustard in Different Varieties and Sowing Dates

Ecological engineering plays an important role in Integrated Pest Management. Considering this, a field experiment was conducted at the Students’ Instructional Farm (SIF), Chandra Shekhar Azad University of Agriculture and Technology, Kanpur during the rabi season of 2020-21. The severity of the mustard aphid, Lipaphis erysimi (Kalt.) in mustard (Brussica juncea L.) crop and its period of occurrence were not uniform in two successive crop seasons. The highest aphid intensities of 120.8 aphids per plant, 138.0 aphids per plant, 148.7 aphids per plant, and 176.1 aphids per plant were recorded on mustard varieties Varuna, Varuna, Azad Mahak, and Ashirwad, respectively, during mid-February (6th MSW) when the mustard was planted on 13th November, 23rd November, 25th November, and 10th December 2020. A negative correlation was established between the average temperature (r = -0.3599) and the actual intensity of aphids, as well as the weekly increase of aphids (r = -0.5838). On the other hand, average relative humidity had a positive influence on aphid incidence. The potentiality of predatory beetles (coccinellids) in the mustard ecosystem was found to be weather-dependent. The weather factors favourable for aphid multiplication did not support the enhancement of the population of predatory ladybird beetles.