Juvenile hormone and octopamine in the regulation of division of labor in honey bee colonies.

Forager honey bees have high circulating levels of juvenile hormone (JH) and high brain levels of octopamine, especially in the antennal lobes, and treatment with either of these compounds induces foraging. Experiments were performed to determine whether octopamine acts more proximally than JH to affect the initiation of foraging behavior. Bees treated with octopamine became foragers more rapidly than bees treated with the JH analog methoprene. Bees treated with methoprene showed an increase in antennal lobe levels of octopamine, especially after 12 days. Bees with no circulating JH (corpora allata glands removed) treated with octopamine became foragers in similar numbers to bees with intact corpora allata. These results suggest that JH affects the initiation of foraging at least in part by increasing brain levels of octopamine, but octopamine can act independently of JH. Effects of JH that are not related to octopamine also are possible, as bees treated with both octopamine and methoprene were more likely to become foragers than bees treated with only octopamine or methoprene.