Biotic and Abiotic Factors as Variables in Population Build-up of Mustard Aphid (Lipaphis erysimi Kalt.) in the Western Gangetic Planes of India

An experiment was conducted at the Crop Research Centre, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut (U.P.) during Rabi season 2021-22. During the course of research, observations were made to study the incidence and fluctuations in population build-up of Mustard Aphid, Lipaphis erysimi Kalt. due to variations in abiotic factors including temperature, precipitation rates, daylight hours, humidity as well as biotic factors such as natural enemies as for example, predators like grubs and adults of lady bird beetle, Coccinella septumpunctata etc., The maximum aphid population 164 aphid/10 cm shoots were recorded in the third standard week of February. Appearance of grubs and adults of lady bird beetle in the first week of December and maximum population reached in synchronization with the maximum population of aphid i.e., 4.12 beetle or grubs per 10 shoots in the month of February. Simple correlation studies revealed the instantaneous effects of meteorological variables on the population progression of aphids, the temperature had the biggest influence in the fluctuations of number of aphids per plant shoot. The appearance of predators was positively correlated with temperature, whereas a negative correlation with the incidence of mustard aphid was observed. Additionally, there was a positive correlation between the population of aphid and relative humidity.