Influence of Abiotic Factors on the Occurrence of Mustard Aphid, Lipaphis erysimi (Kalt.) on Indian Mustard (Brassica juncea L.)

Mustard (Brassica juncea) is a major oilseed crop in India, valued for its high oil content, nutritional significance, and diverse industrial and agricultural applications. However, its productivity is substantially constrained by insect pests, particularly the mustard aphid (Lipaphis erysimi), which is responsible for considerable losses in both yield and quality. A field experiment was undertaken to investigate the effects of abiotic factors on the incidence of the mustard aphid (Lipaphis erysimi Kalt.) infesting Indian mustard (Brassica juncea L.) at the Entomology Research Farm, College of Agriculture, Rajmata Vijayaraje Scindia Krishi Vishwa Vidyalaya (RVSKVV), Gwalior, Madhya Pradesh. The results indicated that aphid infestation was first recorded during the 52nd Standard Meteorological Week (SMW), with a mean population of 8.4 aphids per 10 cm of the central apical twig per plant. The population subsequently increased, reaching a peak during the 6th SMW, with an average density of 193.00 aphids per 10 cm of the central apical twig per plant. This peak infestation coincided with prevailing maximum and minimum temperatures of 25.7°C and 6.8°C, respectively. These findings highlight the critical role of abiotic factors, particularly temperature, in influencing the population dynamics of mustard aphid. Minimum temperature showed a significant negative correlation (-0.838*), suggesting that lower temperatures corresponded with higher aphid populations. Maximum temperature and morning relative humidity exhibited a positive but statistically non-significant association, whereas evening relative humidity and rainfall demonstrated a negative, non-significant relationship. Conclusion is that the aphid population is maximum in the February 2nd week so that the management practices should be applied to reduce the population level below economic damage.