Functional response of grub and adult of Coccinella septempunctata (L.) and Coccinella transversalis (Fabr.) on mustard aphid, Lipaphis erysimi (Kalt.)

Abstract

Studies were conducted in the laboratory of Entomology, Institute of Agricultural Sciences, BHU, Varanasi to determine the effect of different prey (aphid) densities (functional response) of second, third, fourth instars of grub and adult of two important aphidophagous coccinellids, Coccinella septempunctata (L.) and Coccinella transversalis (Fabr.) i.e. 20, 40, 80, 100, 200, 400 and 800, during 2003 and 2004. The present study revealed that the prey density has significant influence on the preying capacity of the grub and adult of both species. Prey consumption by the second, third, fourth instars of grub and adult of Coccinella septempunctata (L.) and Coccinella transversalis (Fabr.) followed an increasing trend from lower prey density (20) to higher prey densities i.e. 40, 80, 100, 200, 400 and 800, while the percentage of prey consumption decreased with increasing prey (aphid) densities. It was also observed that functional response of fourth instar grub was found to be maximum (287.7 ± 2.87) (187.7 ± 2.56) followed by third instars, adult and second instar grub of C. septempunctata and C. transversalis on prey density of 800, respectively. The determination factor (R 2) was found to be significant.