Octopamine influences division of labor in honey bee colonies

Forager honey bees have higher brain levels of octopamine than do bees tend ing larvae in the hive. To test the hypothesis that octopamine influences h oney bee division of labor we treated bees orally with octopamine or its im mediate precursor tyramine and determined whether these treatments increase d the probability of initiating foraging. Octopamine treatment significantl y elevated levels of octopamine in the brain and caused a significant dose- dependent increase in the number of new foragers. This effect was seen for precocious foragers in single-cohort colonies and foragers in larger coloni es with more typical age demographies. Tyramine treatment did not increase the number of new foragers, suggesting that octopamine was exerting a speci fic effect. Octopamine treatment was effective only when given to bees old enough to forage, i.e., older than 4 days of age. Treatment when bees were 1-3 days of age did not cause a significant increase in the number of new f oragers when the bees reached the minimal foraging age. These results demon strate that octopamine influences division of labor in honey bee colonies. We speculate that octopamine is acting in this context as a neuromodulator.