Influence of host insect derived kairomones on parasitic/predatory activities of natural enemies against eggs of Earias vittella (Fab.) and Helicoverpa armigera (Hübner)

Hexane extract (1000 ppm) of various parts including wing scale, female whole body and 3^rd instar of Corcyra cephalonica were tested under laboratory conditions for their kairomonic activity to enhance the parasitic/predatory activities of Trichogramma chilonis and Chrysoperla zastrowi sillemi against eggs of Earias vittella and Helicoverpa armigera. Treatment of irradiated eggs of E. vittella with hexane extract of female whole body of C. cephalonica (1000 ppm) recorded the parasitization of 44.6% by Trichogramma chilonis on 3^rd day after inoculation which tended to increase to 65.6 and 72.4% on 5^th and 7^th day after inoculation and they were 8.9, 12.5 and 14.8% in hexane alone treated eggs on 3^rd, 5^th and 7^th day after inoculation, respectively. The highest predation by C. cephalonica on hexane extract of female whole body treated eggs of E. vittella was recorded (75.7%) whereas it was 19.4% in hexane treated eggs. Similarly, female whole body extract of C. cephalonica enhanced the parasitic activity of T. chilonis on eggs of H. armigera by enhancing the parasitization from 23.0% (hexane treated eggs) to 77.0% (female whole body extract treated eggs) while the predatory activity of C. carnea was enhanced from 26.1 to 81.8%.