The use of honeydew in foraging for aphids by larvae of the ladybird beetle, Coccinella septempunctata L. (Coleoptera: Coccinellidae)

Abstract

Abstract 1. To clarify the use of honeydew in foraging for aphids by larvae of the ladybird beetle, Coccinella septempunctata L., searching behaviour of ladybird larvae for Aphis craccivora Koch and Acyrthosiphon pisum Harris and the abundance of honeydew under aphid colonies were examined in laboratory experiments.2. More larvae responded by climbing the plants with aphids than responded to plants without aphids. When the plants were replaced with sticks, in order to exclude visual and olfactory cues from plants and aphids, more larvae of C. septempunctata climbed sticks above the area that contained honeydew than climbed sticks above the area that did not contain honeydew. Then, ladybird larvae use honeydew as a contact kairomone when foraging for aphids.3. Aphis craccivora deposited a larger number of honeydew droplets beneath the plants than did similar numbers of A. pisum. Thus, C. septempunctata larvae licked more frequently the honeydew of A. craccivora than that of A. pisum and spent longer searching on the area containing honeydew of A. craccivora than that of A. pisum. Consequently, a larger number of larvae climbed a stick above honeydew of A. craccivora than that of A. pisum.4. It may be also considered that C. septempunctata larvae can distinguish honeydew of the two aphid species and respond more strongly to A. craccivora than A. pisum.