Pantnagar Journal of Research

Abstract

The present study investigated the seasonal dynamics of Helicoverpa armigera larval population in relation to weekly meteorological variables during the rabi seasons of 2023-24 and 2024-25. Weekly larval density per plant was recorded and examined in relation to mean temperature, relative humidity, rainfall and sunshine hours. Larval population remained negligible during early winter but increased sharply from the 10th SMW onward, attaining peak densities of 8.500 larvae/plant in 2023-24 and 8.200 larvae/plant in 2024-25. To quantify weather–population relationships, Poisson generalized linear models with lagged weather variables were employed. During 2023-24, temperature at one-week lag showed a highly significant positive effect (β = 0.263; p = 0.001), indicating nearly a 30% increase in expected larval density per 1 ^°C rise, while sunshine at one-week lag was also significant (β = 0.247; p = 0.044). In contrast, during 2024-25, sunshine at one-week lag exerted the strongest influence (β = 0.797; p < 0.001), corresponding to more than a two-fold increase in larval abundance per additional sunshine hour, whereas temperature at two-week lag showed a significant negative effect (β = -0.236; p = 0.032). Relative humidity and rainfall exhibited weak or inconsistent associations in both seasons. The findings highlight the importance of antecedent thermal and solar conditions in regulating H. armigera larval population dynamics and provide insights useful for weather-based pest management strategies.