Effect of certain weather parameters on population fluctuation of gram pod borer (Helicoverpa armigera Hubner) in chickpea

Chickpea is the major pulse crop grown in India and it is major protein source for many Indians. It is subjected to severe damage by pod borer, Helicoverpa armigera (Hubner) which causes yield loss of 400 kg/ha. H. armigera is a polyphagous pest with wide host range and is subjected to heavy insecticidal sprays in various crops. The climatic factors like rainfall, temperature, humidity and sunshine hours mainly influence the abundance of H. armigera. During 2015-16 and 2016-17, a bulk chickpea plot of 100m2 was raised at Institute of Agricultural Sciences, BHU, Varanasi. The experimental plot was maintained without any insecticidal sprays and the number of H. armigera larvae was counted randomly from 10 plants on standard week interval basis. During 2015-16 and 2016-17, H. armigera larval population was first observed on 4th standard week (Jan 22-28). A peak larval population was observed on 9th standard week (9.31 larvae per 10 hills) and 10th standard week (9.87 larvae per 10 hills) during 2015-16 and 2016-17, respectively. The larval population was observed in the field till the maturity of the crop. Correlation studies revealed that the H. armigera larval population was correlated as significantly positive with sunshine hours during 2015-16 and 2016-17. Maximum and minimum temperature had a positive non significant correlation with larval population during both years of experimentation. Further, rainfall, morning relative humidity and evening relative humidity were observed to be non significantly correlated with H. armigera larval population.