EFFECTS OF STRESS, AGE, SEASON, AND SOURCE COLONY ON LEVELS OF OCTOPAMINE, DOPAMINE AND SEROTONIN IN THE HONEY-BEE (APIS-MELLIFERA L) BRAIN

The effects of environmental and genetic factors on levels of octopamine, dopamine and serotonin in brains from worker honey bees (Apis mellifera L.) were measured using high-performance liquid chromatography with electrochemical detection. Exiting foragers were stressed by clamping their legs, which resulted in peak elevation of octopamine and serotonin after 10 min. Significant seasonal differences in levels of all three biogenic amines were found for bees sampled from an observation colony during the spring, summer and autumn of 1990. Levels of the amines were highest during June-September, corresponding to high levels of colony foraging activity, These differences may reflect seasonal changes in colony nutrition, population size, or brood-rearing activity. The levels of all three amines were significantly lower in the brains of newly emerged bees than in brains from randomly aged worker bees from the same colony. Since the total protein content in bee brains was not different for bees from these two groups, age-related differences were not related to brain growth. Significantly different levels of octopamine, dopamine and serotonin were detected among workers in colonies that contained unrelated queens.