Weather influenced seasonal dynamics of key insect pests and natural enemies in Mustard ecosystem

Abstract

The study was conducted on mustard during the rabi season of 2022-23 identified three major pests: aphid (Lipaphis erysimi), sawfly (Athalia lugens proxima), and painted bug (Bagrada cruciferarum), which caused significant crop losses at different growth stages. The highest aphid population was recorded during the 7th SMW, with 110.80 aphids per 10 cm of the central twig plant-1 at the siliqua formation stage. The aphid population showed a significant positive correlation with sunshine (r=0.514*, respectively). Additionally, the aphid population had a significant positive correlation with coccinellids and syrphid flies (r = 0.662** and r = 0.598*, respectively). Natural enemies played a crucial role in controlling the aphid population suppression. The highest density of mustard sawfly larvae was recorded during the 49th SMW, with 1.80 larvae plant-1, and it showed a significant negative correlation with relative humidity and windspeed (r = -0.58* and r = -0.54*). The painted bug population peaked during the 8th SMW, with 2.20 bugs plant-1, and showed significant positive correlations with maximum temperature (r = 0.511*) and as well as sunshine (r = 0.547*, respectively). Multiple regression analysis exhibit that weather factors including maximum and minimum temperatures, relative humidity, sunshine hours, Coccinellids and Syrphid fly collectively explained 75.80% (R² = 0.758) of the variability in aphid, while maximum and minimum temperatures, relative humidity, sunshine hours,67.10% (R² = 0.671), 59.40% (R² = 0.594) of the variability in saw fly and painted bug, respectively.