The social organization of advanced eusocial insects largely depends on chemical signals that act as a communication channel between the single individuals of a colony (e.g., Wilson 1971). For example, the queen pheromone of the honeybee is well investigated and does have an important function in the regulation of reproduction (Free 1987). In order to identify the queen signal of the stingless bee Melipona beecheii we studied the volatile odor bouquets of workers, virgin queens, and physogastric queens of this species in Costa Rica. Scent was collected by placing bees individually in tightly closed, clean glass vials for 30min. After removing the bees, each vial was put in a freezer at –8°C for 1h to condense chemical compounds at its wall. Subsequently, the inside of the bottles was rinsed with 1.5ml pentane for 90s to extract the compounds. By means of gas chromatographic analyses coupled to electroantennographic detection (GC-EAD) we found that 16 compounds from the physogastric- and virgin queens’ odor bouquets elicit a response in the chemoreceptors on the workers’ antennae. The relative proportions of these compounds in the odor bouquets of physogastric and virgin queens differs. Furthermore, most of these substances are absent in the workers. Our results indicate that the active, queen specific substances may act as a queen signal. They are likely to be involved in two important contexts: (i) as information that the colony is queen right and (ii) for discrimination of workers from virgin queens, which normally are killed by the workers unless the physogastric queen dies or the nest is divided in order to initiate a daughter colony. Future bioassays with synthetic compounds of identified odor components will test these hypotheses.

Free J.B. 1987. Pheromones of Social Bees. Chapman and Hall, London

Wilson E.O. 1971. The Insect Societies. Harvard University Press, Cambridge