Predator deterrence by mandibular gland secretions of bees (Hymenoptera: Apoidea)

Volatile lipids from the mandibular gland secretions of bees (Hymenoptera: Apoidea) are potent olfactory repellents of foraging ants (Formica, Crematogaster) in biologically relevant contexts and quantities. In contrast, differential success in capture of bee and fly prey by predatory asilid flies (Efferia), reduviid bugs (Apiomerus), and arachnids (Agelenopsis, Argiope) is better explained by prey size than by chemical repellence, aposematism, or possession of a sting. Supernormal doses of some allomones, applied to worker honeybees (Apis mellifera) that were fed toArgiope aurantia spiders, elicted more frequent preenvenomation pauses following ensnarement but did not significantly increase other prey-handling times. These pauses merely delayed the bee's demise. Mandibular gland secretions of solitary bees augment their other secondary defenses in at least two contexts: (1) during intranest encounters when repelling intruding ants, and (2) retaliation delivered to their arthropodan predators which, if the bee is nearly too large for the predator to handle, may allow the bee to escape.