No abstract

Honey bee queens produce a sophisticated array of chemical signals (pheromones) that influence both the behavior and physiology of their nest mates. Most striking are the effects of queen mandibular pheromone (QMP), a chemical blend that induces young workers to feed and groom the queen and primes bees to perform colony-related tasks. But how does this pheromone operate at the cellular level? This study reveals that QMP has profound effects on dopamine pathways in the brain, pathways that play a central role in behavioral regulation and motor control. In young worker bees, dopamine levels, levels of dopamine receptor gene expression, and cellular responses to this amine are all affected by QMP. We identify homovanillyl alcohol as a key contributor to these effects and provide evidence linking QMPinduced changes in the brain to changes at a behavioral level. This study offers exciting insights into the mechanisms through which QMP operates and a deeper understanding of the queen's ability to regulate the behavior of her offspring.Apis mellifera ͉ biogenic amines ͉ neuroethology ͉ neuromodulation ͉ pheromonal communication C omplex social interactions require systems of communication that are reliable and unambiguous. The honey bee, Apis mellifera, employs Ͼ50 substances to communicate with and to organize its colony, and the information that is conveyed between colony members is both subtle and sophisticated (1-3).Maintaining colony organization is a primary role of the queen, whose pheromones enable her to regulate not only the behavior but also the physiology of her nest mates. The most striking effects are those of queen mandibular pheromone (QMP), a chemical blend that induces young workers to feed and groom the queen (Fig. 1) and primes bees to perform colonyrelated tasks (4, 5). The retinue of workers that attend the queen facilitates the distribution of QMP throughout the colony, where it inhibits the rearing of new queens (6), helps prevent the development of worker ovaries (7), influences comb-building activities, (8) and affects the biosynthesis of juvenile hormone (9) [and hence the age-related behavioral ontogeny of recipient workers (10)]. Despite QMP's central role in the normal functioning and organization of honey bee colonies, very little is known about the cellular mechanisms through which it operates.We were intrigued by one of the key components of QMP, homovanillyl alcohol (HVA) (4). HVA (4-hydroxy-3-methoxyphenylethanol) bears a striking structural resemblance to dopamine (see Fig. 1 Right), a biogenic amine that plays a central role in insect behavioral regulation and motor control (11-18). The presence of this compound within the pheromone blend suggested to us that dopamine function in the brain of recipient bees might be affected by exposure to QMP. To test this hypothesis, we exposed young workers to QMP and examined its effects on brain dopamine levels, levels of dopamine receptor gene expression, and cellular responses to this amine. The results provide compelling evidence that QMP al...