Public use of olfactory information associated with predation in two species of social bees

Recent studies have documented that social bees can use heterospecific information to find or avoid food resources, but little is known about whether bees gain information from heterospecifics about predation risk. We report the first detailed field tests in bees of hetero- and conspecific avoidance of olfactory information associated with predation. We determined whether Apis mellifera and Bombus impatiens would respond either to hetero- or conspecific haemolymph as an indication of a predation event, or to sting gland contents, which provide an alarm pheromone in honeybees and in many other social Hymenoptera. Bombus impatiens avoided their own haemolymph and A. mellifera haemolymph in foraging arena choice experiments. Bombus impatiens did not respond to A. mellifera alarm pheromone or to the odour of conspecific sting gland. In field experiments, A. mellifera avoided their own haemolymph and their own sting alarm pheromone, but did not avoid the haemolymph or sting gland contents of B. impatiens or native bumblebees (Bombus vosnesenskii) that regularly foraged around their hives. One factor behind the response of B. impatiens to heterospecific cues of predation may be its habit of solitary foraging, which may lead to more interactions with heterospecifics than would social foraging in which bees recruit nestmates to resources.