Investigations on the cannibalistic behavior of ladybird beetle coccinella septempunctata L. (Coleoptera: Coccinellidae) under laboratory conditions

Abstract

Cannibalism or intraspecific predation, where one species feeds on individuals of its own species, is a widespread phenomenon in most aphidophagous coccinellids. Laboratory studies were conducted on the cannibalistic behavior of various developmental stages of Coccinella septempunctata L. (Coleoptera: Coccinellidae) in the presence and absence of natural food, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae). In both the presence and absence of aphids, the eggs and 1st and 2nd instars of C. septempunctata were cannibalized by the adults, and the level was inversely related to the availability of aphids. The same was also true for cannibalism of eggs by larvae and within the larval stages, with older larvae consuming significantly higher numbers of eggs and younger larvae in the absence of aphids. The adults and 4th instar larvae also consumed a considerably higher number of eggs, even in the presence of aphids. Within the same stage/age of larvae, the level of cannibalism increased with each larval stage from minimum among 1st instars and maximum among 4th instars. The studies showed that a low density or scarcity of prey was the main cause of cannibalism in C. septempunctata.