Weather based prediction of Chickpea Helicoverpa armigera population in Bundelkhand agroclimatic zone of Madhya Pradesh

An attempt was made to find out the impact of rainfall, temperature and growing degree day (GDD) on the larval incidence and peak population of Helicoverpa armigera on chickpea and its growth in the Bundelkhand Agroclimatic zone of Madhya Pradesh. Besides, an attempt was also made to examine the association with weather variables of rising and falling phase of the larval population of Helicoverpa armigera. It was found that there was not any significant impact of monthly (September and October) rainfall on the larval population but the monthly rainfall of January and February significantly influenced the incidence of the pod borer and GDD plays a vital role in increasing and decreasing of its peak population. Minimum temperature and rainfall play a crucial role for larval incidence and its population growth. Growing degree day from 1st January to 15th February were presented in relation to the number of peak larval population in chickpea. The correlation of weather factors with larval population was also presented and different weather parameters were screened for its prediction and management. A multiple regression equation was also developed. It was found that if the cumulative growing degree day from 1st January to 15th February 350 degree day and weekly minimum temperature ranged from 6 to 12 C along with number of rainfall events  5 days, then number of larval population of H. armigera in chickpea is high and vice-versa. This study will be very useful not only for forecasting the peak larval population of H. armigera in chickpea but in formulating effective pest management strategies too.