Effect of different temperatures on the number of host eggs parasitized by trichogramma chilonis ischii at different densities of its host Helicoverpa armigera (hübner)

The egg parasitoids of the genus Trichogramma have been used successfully as inundative biological control agents against a range of agricultural pests mainly lepidopterans and are the most widely used natural enemies in biological control worldwide. Parasitoids depend on a series of adaptations to the ecology and physiology of their hosts and host plants for survival and are thus likely highly susceptible to changes in environmental conditions. Temperature is one of the most important environmental factors influencing physiology and behavior of insects including parasitoids. The aim of this study was to describe functional responses of Trichogramma chilonis Ishii on Helicoverpa armigera (Hübner) infesting pigeonpea at four temperatures viz. 12, 17, 22 and 27oC that represent a common range of daytime temperatures in northeastern Uttar Pradesh during October (When plant starts flowering) to December (when pods starts maturing) and when Helicoverpa armigera (Hübner) populations can exceed the Economic Injury Level (EIL) and natural enemies can be important for their control.