Interaction of ants with aphid enemies: Do inexperienced ants specializing in honeydew collection recognize aphidophages at their first contact?

Abstract

Honeydew collectors of Formica pratensis taken from the nature (control) and laboratory-reared “naive” ants, which had never met either “mature” workers or aphids and aphidophages, were observed during their interactions with various aphid enemies: adults and larvae of ladybirds and lacewings, and larvae of syrphid flies. The naive ants were significantly more aggressive towards adults than towards larvae of aphidophages. More than 70% of the naive ants treated ladybirds and lacewings as enemies at their first encounter and attacked them immediately without any prior antennation. The frequency of aggressive reactions (body jerking and bites) towards larvae was significantly higher in the control group, whereas the percentage of ants showing explorative behavior was significantly higher in the naive ants. Overall, experience proved to be not important for displaying the key behavioral reactions towards adult ladybirds and lacewings underlying the protection of trophobionts from these natural enemies. However, accumulation of experience is assumed to play an important role in the recognition of aphidophage larvae and formation of aggressive behavior towards them.