M. K. MAHAWAR, N. Y. CHANU, R. NAGAR, R. SWAMINATHAN AND H.K. JAIN

A field trial was conducted during rabi, 2014-15 to study the population dynamics of gram pod borer and to assess the loss to chickpea due to the infestation by the pod borer. The standard paired plot design was employed to estimate the losses. The pod borer, Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) was the single key pest. The population of Helicoverpa armigera (Hubner) on chickpea variety Vijay in the untreated plots of the loss estimation trial indicated that the larval numbers were significant from early December, 2014 (6.28 per 4-m row) that reached a peak on 15 December, 2014 (10.51 per 4-m row) and with a seasonal mean of 5.81 larvae per 4-m row. Among the prevailing abiotic factors of the environment, only the mean relative humidity showed a significant negative correlation with the pod borer larval population (r = - 0.64*). The pod borer larvae were parasitized in nature by the parasitoid, Uchida from Campoletis chlorideae 22 December, 2014 with 3.53 per cent parasitisation that increased to a maximum of 12.35 per cent the next week on 29 December, 2014. The plant stand was 30 per cent more when the crop was treated with insecticides and kept pest-free. The mean larvae per plant were 6 times more and the mean numbers of damaged pods per plant were 7.7 times more when the crop was untreated and exposed to the pod borer infestation. On the basis of yield, a loss of 26.57 per cent was recorded due to infestation.