Weather Parameter's Impact on Natural Parasitization by Campoletis chlorideae Uchida in Chickpea Ecosystem - New Alluvial Zone of West Bengal

A major biotic constraint in chickpea (Cicer arietinum L.) production is gram pod borer, Helicoverpa armigera (Hübner). However, the population of this pest is reduced to some extent by a solitary endo-larval parasitoid, Campoletis chlorideae Uchida under field conditions. Climate change has a greater impact on natural enemies’ effectiveness used in field-level pest management. Therefore, the present study was conducted to understand the impact of weather factors on C. chlorideae parasitization rate of H. armigera in chickpea grown in the new alluvial agro-climatic zone of West Bengal.

Chickpea was grown in a randomized complete block design (RCBD) with three replications during Rabi 2017-18, 2018- 19 and 2019-2020, at Mondouri Farm, Bidhan Chandra Krishi Visawavidayala, Mohanpur, West Bengal. To know the most significant weather parameter which influences C. chlorideae parasitization or parasitoid incidence, H. armigera larvae (2^nd instar) collected from the field experiment were reared until cocoon formation and parasitization % was correlated with weather parameters and subsequently subjected to stepwise regression analysis.

The larval endo-parasitoid, C. chlorideae marked its first appearance from 3^rd SMW after the appearance of H. armigera and its activity was high (68% to 72% parasitization) during the flowering to pod initiation stage and thereafter declined gradually. Among the weather variables, only temperature (maximum and minimum) had a consistent and significant negative correlation with C. chlorideae incidence and was responsible for nearly 50% C. chlorideae incidence. An increase in 1°C temperature results in a decrease of 4% parasitoid incidence. Thus, climate change in the near future will have a considerable influence on the overall survival, development and rate of parasitization of parasitoids.