Weather-Mediated Population Fluctuations of Gram Pod Borer, Helicoverpa armigera (Hubner) in Chickpea (Cicer arietinum L.): A Correlation and Regression Analysis

Abstract

A field experiment was conducted to determine the population dynamics of Helicoverpa armigera (Hubner) larvae in relation to abiotic factors on chickpea (Cicer arietinum L.) during two consecutive Rabi seasons, 2024-25 and 2025-26, at the Students’ Instructional Farm (SIF), C.S.A. University of Agriculture and Technology, Kanpur. The larval population first appeared at a density of 0.20 larvae/plant during the 2nd and 1st Standard Meteorological Weeks (SMWs) in 2024-25 and 2025-26, respectively. The population subsequently increased, reaching peak densities of 3.60 and 4.20 larvae/plant during the 11th SMW in 2024-25 and 2025-26, respectively. Thereafter, the larval population declined to 3.20 and 2.80 larvae/plant during the 12th SMW, respectively. At peak infestation, the maximum temperatures were 33.40 and 34.60°C, while the minimum temperatures were 17.40 and 17.30°C during 2024-25 and 2025-26, respectively. Bright sunshine durations were 8.80 and 7.10 h, respectively, and no rainfall was recorded during peak infestation in either season. Correlation analysis revealed significant positive relationships between larval population and maximum temperature (r = 0.64 and 0.56) and bright sunshine hours (r = 0.66 and 0.59) during 2024-25 and 2025-26, respectively. Evening relative humidity showed significant negative correlations with larval population during both 2024-25 (r = -0.70) and 2025-26 (r = -0.51). Minimum temperature showed a non-significant positive correlation during 2024-25 (r = 0.48NS) but a significant positive correlation during 2025-26 (r = 0.60). Morning relative humidity showed a significant negative correlation in 2024-25 (r = -0.56) and a non-significant negative correlation in 2025-26 (r = -0.38NS), while rainfall showed non-significant negative correlations (r = -0.25NS and -0.17NS) during 2024-25 and 2025-26, respectively. Multiple linear regression analysis indicated that the combined abiotic factors accounted for 66.37% and 76.0% of the variation in H. armigera larval population during 2024-25 and 2025-26, respectively. These findings indicate that weather parameters, particularly temperature, relative humidity and bright sunshine hours, are associated with the seasonal population dynamics of H. armigera on chickpea.