Status of pod borer Helicoverpa armigera (Hubner) Pigeonpea and its association with climatic variations at a hot semi-arid eco-region of Southern India

Seasonal dynamics of Helicovera armigera (Hubner) was studied on pigeonpea for eight consecutive seasons (2011 -18) at Vamban (Tamil Nadu). Onset of H. armigera was at the earliest [44 standard meteorological week (SMW)] and latest (50 SMW) in respect of 2012 and 2015, both coinciding with 16 weeks of crop age (CA). Periods of H. armigera peak varied between 47 (2012) and 5 SMWs with 2013, 2014, 2015 and 2018 seasons having peak during 13, 18, 23 and 20 weeks of CA, respectively. Status of H. armigera analyzed using one way ANOVA both on SMW and CA basis indicated the highest mean population in 2018 and the lowest during 2011. Significant correlations of H. armigera with sunshine hours (r = 0.25**; P<0.01), maximum temperature (−0.19*; P<0.05), minimum temperature (−0.17*; P<0.05) and rainy days (−0.18*; P<0.05) were noted. Increasing population levels of H. armigera with significantly rising MaxT (2.27°C), mean T (1.04°C) and reducing rainfall (−4.66°C) in addition to a declining but non-significant. MinT (−0.17°C) was the impact of climatic variability at Vamban located in East Coast plain and hills of Tamil Nadu in Southern India. Identified climatic variations of current decade at Vamban (TN) could serve for studies on impact of climate change on population dynamics of other insects and diseases.