Kairomonal effect of acetone extracts of Pennisetum glaucum (L.) and their influence on parasitic and predatory potential of Trichogramma chilonis Ishii and Chrysoperla zastrowi sillemi (Esben-peterson)

Semiochemicals especially their alkane constituents played vital role in governing the foraging behaviour of natural enemies. Thus, in the present study, concentration (1% or 10, 000 ppm) of the acetone extract of various plant parts of bajra were prepared to determine the specific acetone extract of bajra (Pennisetum glaucum) plant part(s) to optimizing the foraging behaviour of Trichogramma chilonis and Chrysoperla zastrowi sillemi. Laboratory bioassay with acetone extract of young leaves, old leaves, flowers and stems of bajra plant with T. chilonis and C. zastrowi sillemi revealed their kairomonal activities in vitro. Treating irradiated eggs of Corcyra cephalonica with acetone extract of flowers of bajra recorded the parasitization of 20.1% by T. chilonis on 3^rd day after inoculation which increased from 54.2 to 76.3% on 5^th and 7^th day after inoculation and were 8.1, 20.4 and 21.6% when the eggs were treated with acetone alone on 3^rd, 5^th and 7^th day after inoculation, respectively. Maximum emergence (68.4%) was observed with acetone extract of flowers followed by acetone extract of young leaves (52.4%). The highest predation by C. zastrowi sillemi on acetone extract of flowers treated eggs of C. cephalonica was recorded (69.6%) whereas it was 25.6% in acetone treated eggs.