Density and stage-specific functional response of Coccinella septempunctata L. (Coleoptera: Coccinellidae) on the larvae of Epilachna vigintioctopunctata (Coleoptera: Coccinellidae)

Abstract

Epilachna vigintioctopunctata is a voracious pest of several economically important agricultural crops worldwide, but relatively few studies have focused on the feasibility of its predators in controlling Epilachna beetles. This study investigated the predatory efficiency and functional response of Coccinella septempunctata to varying densities of E. vigintioctopunctata. Our laboratory experiments revealed that larval and adult C. septempunctata attacked and preyed on Epilachna larvae and showed Type II functional response except when they were at the 1st instar stage. Based on three key parameters in the functional response, the 4th instar of C. septempunctata was found most efficient as a predator. The mean prey consumption increased with increasing prey density and growth stage of C. septempunctata. Predatory efficiency did not differ significantly among 4th instar, adult females, and males. However, the feeding percentage was inversely related to the density and higher at low prey densities. Our study concluded that 4th instar larvae and adults of C. septempunctata were most influential in suppressing E. vigintioctopunctata and this ladybird beetle could help reduce pesticide use and protect agroecological environments.