Biogenic amines are among the best known neuromodulators in both vertebrates and invertebrates. They have been implicated in the control of numerous forms of behavior whose expression is influenced by changes in both environmental and physiological conditions. Neuromodulators act by modifying the effects of hormones and neurotransmitters to modulate nervous system responses to various stimuli. Their broad distribution in the brain and other parts of the nervous system allow them to act on many neurons.
The biogenic amines dopamine, serotonin, and octopamine are found in all parts of the honey bee brain. In the antennal lobes, foragers have higher levels of all three amines than do nurses, regardless of age. Differences are larger for octopamine than for dopamine or serotonin. In the mushroom bodies, older bees have higher levels of all three amines than younger bees, regardless of behavioral state. These correlative results suggest that increases in octopamine in the antennal lobes may be particularly important in the control of age-related division of labor in honey bees.
Recent experiments have shown that oral treatments of octopamine, but not serotonin, accelerate the rate at which young bees become foragers. This octopamine treatment effect is both dose-dependent and time-dependent. Bees treated early in life as pre-foragers and then switched to being untreated do not become foragers at an earlier age, while young bees treated around the time at which foraging becomes possible do show accelerated behavioral development. This supports the idea that octopamine acts as a neuromodulator of division of labor, suggesting that high levels are necessary at a time when foraging is possible to alter the responses of other neurons to specific task-related stimuli.Representative Publications
Schulz DJ, Robinson GE (2001) Octopamine influences division of labor in honey bee colonies. J. Comp. Physiol. A 187:53-61. (pdf)
Schulz DJ, Robinson GE (1999) Biogenic amines and division of labor in honey bee colonies: behaviorally related changes in the antennal lobes and age-related changes in the mushroom bodies. J. Comp. Physiol. A 184:481-488. (pdf)
Wagener-Hulme C, Kuehn JC, Schulz DJ, Robinson GE (1999) Biogenic amines and division of labor in honey bee colonies. J. Comp. Physiol. A 184:471-479. (pdf)