Omkar ¹, Barish E. James ¹

Affiliations
1 Department of Zoology, University of Lucknow Lucknow 226007, Uttar Pradesh, IN

Abstract

Searching and feeding efficiency of a predaceous ladybird beetle, Coccinella transversalis Fabricius was investigated for brinjal aphid, Aphis gossypii Glover at varying predator and prey densities. Rate of prey consumption per predator decreased with increase in the number of predators, due to mutual interference (0.90) amongst the larvae. Searching efficiency (area of discovery) of fourth instar larvae decreased from 0.1846 to 0.0779 when one, two, four and eight predators were exposed to a constant prey density (200). Prey consumption by a single larva increased with increase in prey densities but the percent prey consumption decreased. Maximum percent prey consumption was noticed at the lowest prey density (50) and minimum at highest prey density (800). Searching efficiency of a fourth instar larva decreased from 1.7263 to 0.4727 with increase of prey density from 50 to 800 individuals of A. gossypii. The predator-prey ratio of 1:50 may be considered optimal for the augmentative release of C. transversalis for the biocontrol of A. gossypii.

Keywords

Aphis Gossypii, Coccinella transversalis, Coccinellidae, Coleoptera, Predation, Searching.

Full Text

   

Omkar ¹, Shefali Srivastava ¹

Affiliations
1 Department of Zoology, University of Lucknow Lucknow 226007, Uttar Pradesh, IN

Abstract

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.

Keywords

Aphids, Coccinella septempunctata, Coccinella transversalis, Functional Response, Numerical Response, Searching Efficiency.

Full Text