THE STING SHEATHS OF HONEY-BEE WORKERS (APIS-MELLIFERA L) - STRUCTURE AND ALARM PHEROMONE SECRETION

To evaluate the contribution of the sting sheaths of the worker to the defensive behaviour of a bee colony, we studied their fine structure and the effect of their secretions on the reaction of guards. (1) The structure of the proximal part of the sting sheath integument has all the characteristics of a primitive exocrine gland: porous cuticle with enlarged pore canals and epicuticular pores, and hypertrophied epithelial cells secreting an electron dense material. The non-volatile part of the secretory product embedded the setae of the sheaths. (2) Individual recipient guards in the laboratory and as a group at hive entrances in a beeyard displayed defence behaviour only when stimulated with either sting sheaths or with setaceous membrane, but not with any other gland or organ. Enhanced defensive reaction of guards has been observed when a venom gland or Koschewnikow's glands, are added to either sting sheaths or to setaceous membrane. (3) We demonstrate for the first time that the sting sheaths have the structure of an exocrine gland and that their secretions induce defensive behaviour in guards.