UTTAR PRADESH JOURNAL OF ZOOLOGY

Biological control of insect pests depends upon predating potential of natural enemies, which in turn relate to their functional response that is key to selection of a proper species for the biological control programs. The main aim of the study was to access the functional response of second instar grub of C. zastrowi sillemi (Neuroptera: Chrysopidae) on Raya (Brassica juncea) aphid Lipaphis erysimi (Keltenbach). Five different predator: prey densities of aphids (1:50, 1:100: 1:150, 1:200 and 1:250) were taken and results indicated the type-II functional curve response by logistic regression analysis of C. zastrowi sillemi on L. erysimi. Hollings Type II functional response signifies that the rate of prey consumption by a predator rises as prey density increases, but eventually remains constant in spite of increase in prey density. The aphids consumption, search rate (a`) and maximum predation rate (1/Th) was recorded less (7.36, 0.06 and 0.40) as compared (7.56, 0.068and 0.467) when grubs fed on artificial diet. However, time taken to handle a prey by second instar grub was more (2.55) on natural diet but less (2.17) on artificial diet.