Spatial And Seasonal Variation In Population Dynamics Of Gram Pod Borer, Helicoverpa Armigera (Hübner) Infestations On Chickpea In Tropical Climatic Condition, India

Abstract

Helicoverpa armigera, commonly known as the gram pod borer, is a major pest that poses a significant threat to chickpea (Cicer arietinum L.) cultivation across India, especially in the Rabi season. This study was conducted during the 2023 to 2024 and 2024 to 2025 two consecutive Rabi seasons in Prayagraj, Uttar Pradesh, India, intending to map the temporal and spatial distribution of H. armigera infestations and examine their relationship with key weather variables. Weekly larval counts were recorded from the 5th to the 14th Standard Meteorological Week (SMW). The weather parameters, including temperature, relative humidity and rainfall, were documented and statistically analyzed. The results revealed that H. armigera larval activity began in the 5th SMW and peaked consistently in the 12th SMW during both years, coinciding with the flowering and pod-setting stages of the chickpea crop. Correlation analysis indicated a significant positive association between larval population and maximum and minimum temperatures (r = 0.624 to 0.716) as well as relative humidity (r = 0.750 to 0.873). Rainfall showed no significant influence on pest population dynamics, highlighting the dominance of thermal and humidity-related triggers in the Rabi season. These findings underscore the need for early pest surveillance and climate-informed pest management strategies. The study recommends initiating field monitoring from the 5th SMW and implementing timely interventions based on weather trends to minimize crop losses. The insights also support the development of region-specific pest forecasting models, which can empower farmers with early warning tools and improve the precision of integrated pest management (IPM) programs