Katzav-Gozansky, T., Boulay, R. Francke, W. and Hefetz, A.

Caste specific pheromones are known to function in many colonial activities in honeybees. We recently discovered that Dufour's gland, a gland associated with the sting apparatus, exhibits such caste specificity. Queen glands are more copious and exhibit higher chemical diversity than worker glands. While queenright worker glands contain only odd n-alkanes, queen glands also possess long-chain esters. However, glandular expression is plastic since queenless egg-laying workers produce the major queen-characteristic esters. The amount of secretion in egg laying workers is correlated to the degree of ovarian development. Moreover, the esters are preferentially expressed over the hydrocarbons, contributing largely to the increase in the secretionary volume. Dufour’s gland secretion may function as a component of a complex queen signal that, along with the other sources control, directly or indirectly, colonial activities. To investigate any possible releaser effect of Dufour's gland components we conducted a bioassay for assessing worker attraction to the secretion.. The bioassay demonstrated that queen, but not queenright worker secretion is attractive to workers and that they form a retinue around the source. Moreover queen like secretion of queenless egg-laying workers also elicited significant attraction. Of the glandular components the esters, but not the hydrocarbons, were responsible for the retinue-eliciting behavior. Notwithstanding the retinue-eliciting function of Dufour’s gland secretion it may also serve other functions in the complex queen-worker interactions. The maintenance of reproductive dominance by a single queen in the honeybee colony is more complex than a one-pheromone one-signal system. It can, for example, signal the workers about queen quality - queen fecundity. Supercedure of an old, less fecund queen is common in honeybees as in other eusocial Hymenoptera. Queen signal occurrence in queenright workers, on the other hand, may disclose their potentiality as egg-layers and therefore induce aggression towards them by nestmates.