Impact of Abiotic Factors and Dates of Sowing on Helicoverpa armigera (Hübner) Parasitoid Campoletis chloridae (Uchida) under Chickpea Cropping System in Tarai Region of Uttarakhand

Abstract

Background: The solitary endo-larval parasitoid Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) is an important biocontrol agent of H. armigera in chickpea ecosystem. Abiotic factors are likely to affect the insect host and activity of its parasitoid. Therefore, the present study was conducted to understand the impact of weather factors and different dates of sowing on per cent parasitization of Helicoverpa armigera (Hübner) by Campoletis chlorideae (Uchida) in chickpea ecosystem.Methods: In this field-laboratory investigation were carried out at Pantnagar during the cropping season of 2017-18. Twenty-five larvae of H. armigera (first and second instars) were collected randomly at weekly basis from untreated chickpea crop. In the laboratory, the collected larvae were reared till parasitoid emergence and observed for per cent parasitisation. Result: The observation recorded revealed that mean seasonal parasitism by Campoletis on larvae of H. armigera was found to be 21%, 43.5% and 34.5% in early (20th October), normal (11th November) and late sown crop (1st December), respectively. Various abiotic parameters like maximum and minimum temperature, maximum and minimum relative humidity registered high level of significant association with per cent parasitization in early and normal sown crop compared to the low level of association in late sown crop. The multiple regression analysis showed that the combined effect of all the meteorological parameters were responsible for 90%, 57.9% and 30.5% variation in per cent parasitization in early, normal and late sown crop, respectively.