Feeding potential and foraging behaviour of Cheilomenes sexmaculata (F.) on the cotton aphid, Aphis gossypii glover

Abstract

Feeding potential and foraging behaviour are two important factors which determine the predator’s efficiency of managing prey. Predator-prey system of Cheilomenes sexmaculata (Fabricius) and Aphis gossypii Glover was evaluated to find out the predation efficiency. Feeding potential was observed for different stages of C. sexmaculatus on A. gossypii whereas, functional and numerical responses were ascertained as a function of prey/host density. For the grub stage, highest feeding potential (101.43 ± 3.04 aphids) was observed for the fourth instar which was higher than the gross feeding potential of all other instars. Among the adults, female recorded high feeding potential with a mean daily consumption of 43.13 ± 0.54 aphids. Life table studies showed intrinsic rate of increase (r) of 0.22 with the mean generation time of 27.29 days. The foraging behaviour studies revealed that all the grub stages and adults displayed a type-II functional response. The IV instar grub has shown the lowest handling time with highest maximum predation (96.1aphids/day), followed by female (94.6), male (82.6) and other stages. However, female depicted a rapid extinction of aphid by keeping it below 25, as against fourth instar grub and male which affected extinction by keeping it below 30. So, the releases of fourth instar grub and female of C. sexmaculatus could be advocated for the augmentative biological control of A. gossypii.