Endocrine influences on the organization of insect societies

We review evidence for endocrine influences on division of labor in insect societies. Juvenile hormone (JH) has been studied most extensively. JH is involved in control of four forms of division of labor: division of labor for reproduction among adults, division of labor for reproduction via caste differentiation, division of labor for colony growth and development among adults, and division of labor for colony growth and development via physical castes. Ecdysteroids, biogenic amines, and insulin have begun to be studied in these contexts as well. Ecdysteroids are implicated in the control of caste determination and reproductive maturation in bees. Octopamine influences the division of labor among workers, octopamine and serotonin exert neurohormonal influences on the production of JH by the corpora allata, and octopamine and dopamine levels are correlated suggestively with aspects of reproductive development in bumblebees, honeybees, and paper wasps. Insulin signaling is involved in caste determination and division of labor among workers. Vitellogenin, best known as a yolk protein, may also have hormone-like functions in the regulation of division of labor among workers. We present a verbal model that proposes that evolutionary changes in endocrine function play key roles in the evolution of division of labor.