Comparative Prey Consumption and Searching Efficiency of Coccinella septempunctata Linnaeus and Coccinella transversalis Fabricius on Different Aphid Species

The comparative prey consumption and searching efficiency of fourth instar gruhs of Coccinella septempunctata Linnaeus and Coccinella transversalis Fabricius against three aphid species, viz. Rhopalosiphum maidis (Fitch), Myzus persicae (Sulzer) and Macrosiphmn rosae (Linnaeus) were evaluated to assess the efficiency of these predators in aphid biocontroI. The larvae of C. septempunctata consumed maximum number (245.60±1.92) of M. persicae at prey density of 800 and minimum (18.80±0.88) of R. maidis at prey density of 25 in 24 hours. Fourth instar of C. transversalis consumed maximum number (224.80±1.93) of M. persicae at the prey density of 800 and minimum number (17.40±0.58) of M. rosae at the prey density of 25 in 24 hours. Area of discovery of C. septempunctata and C. transversalis was maximum at the lowest predator (1) and prey-densities (25) of M. persicae. The same was minimum in the case of C. septempunctata and C. transversalis at highest predator (8) and prey- densities (800) of R. maidis and M. rosae, respectively. Prey consumption hy hoth coccinellids increased but their searching efficiency decreased with increase of either prey or predator density. The predatory potential and searching efficiency of C. septempunctata was relatively higher than that of C. transversalis.