Population Buildup of Insect Pest Complex in Summer Green Gram [Vigna radiata (L.)]

Background: Green gram (Vigna radiata) is an important pulse crop grown widely in India, valued for its nutritional content and adaptability to different seasons. However, its productivity is significantly affected by insect pests and environmental factors, with around 25 species causing economic damage. Aims: To correlate the insect pest complex of summer green gram with weather parameters, i.e., maximum temperature, minimum temperature, relative humidity and rainfall. Study Design: Randomized block design (RBD). Place and Duration of Study: Study was conducted at Biswanath College of Agriculture, Biswanath Chariali, during summer 2024. Methodology: Green gram crop was sown by recommended agronomic practices. To monitor insect incidence, five plants were randomly selected from each plot and observed weekly. The insect pest population was assessed by counting their numbers from the randomly selected plants. Finally, insect population data were statistically correlated with weather parameters to study their influence on pest incidence. Results: Aphid, legume pod borer, gram pod borer, green stink bug, coreid bug were identified as pests of green gram in the field. Additionally, two species of coccinellid predators were also recorded as natural enemies. Most pests, including aphid, pod borers, coreid bug, and coccinellids, peaked at the 19th Standard Meteorological Week (SMW), while the green stink bug peaked at the 20th SMW. Aphid showed significant positive and significant negative correlation with maximum temperature and rainfall respectively. Gram pod borer and legume pod borers had a significant positive correlation with maximum temperature and significant negative correlations with relative humidity and rainfall. Green stink bug population was positively correlated with relative humidity, whereas the coreid bug showed a negative correlation with it. Furthermore, coccinellids peaked alongside aphids, displaying a positive correlation with aphid density but a negative correlation with humidity. Conclusion: Overall, pest dynamics were strongly influenced by temperature, rainfall, and humidity, with natural enemies closely tracking aphid abundance.