New Insights into Honey Bee (Apis mellifera) Pheromone Communication. Is the Queen Mandibular Pheromone Alone in Colony Regulation?

Background: In social insects, the queen is essential to the functioning and homeostasis of the colony. This influencehas been demonstrated to be mediated through pheromone communication. However, the only social insect forwhich any queen pheromone has been identified is the honey bee (Apis mellifera) with its well-known queenmandibular pheromone (QMP). Although pleiotropic effects on colony regulation are accredited to the QMP, thispheromone does not trigger the full behavioral and physiological response observed in the presence of the queen,suggesting the presence of additional compounds. We tested the hypothesis of a pheromone redundancy in honeybee queens by comparing the influence of queens with and without mandibular glands on worker behavior andphysiology.Results: Demandibulated queens had no detectable (E)-9-oxodec-2-enoic acid (9-ODA), the major compound in QMP,yet they controlled worker behavior (cell construction and queen retinue) and physiology (ovary inhibition) asefficiently as intact queens.Conclusions: We demonstrated that the queen uses other pheromones as powerful as QMP to control the colony. Itfollows that queens appear to have multiple active compounds with similar functions in the colony (pheromoneredundancy). Our findings support two hypotheses in the biology of social insects: (1) that multiple semiochemicalswith synonymous meaning exist in the honey bee, (2) that this extensive semiochemical vocabulary exists because itconfers an evolutionary advantage to the colony.