Group Response to Alarm Pheromones in Social Wasps and the Honeybee

Abstract

AbstractThe reaction of social wasps and honeybees to alarm pheromones was quantified using a metabolic bio‐assay. Groups of workers placed in an air flow‐through system were exposed for 60 s to the odour of a squashed venom sac and sting apparatus. The reaction of the workers was a stereotyped short term increase in their metabolic activity which was monitored with an infrared CO2‐analyzer. Group size had considerable influence on the reaction of each individual in the group. In honeybees, isolated workers showed weak responses to the alarm stimuli and with increasing group size the reaction per individual rose. Wasps showed the opposite behaviour. Isolated wasp workers generally reacted more intensely than workers in groups. This phenomenon is particularly well expressed in small species (e.g. Paravespula vulgaris). The large workers of Vespa crabro only showed this phenomenon if they were exposed to high doses of 2‐methyl‐3‐butene‐2‐ol, the major compound of their alarm pheromone. We could not elicit any alarm reactions in Polistes gallicus with this metabolic bioassay.