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Hormonal and Genetic Control of Behavioral Integration in Honey Bee Colonies ADVANCED INSECT COLONIES HAVE long been likened to "superorganisms" , a metaphor most apt for traits of colonies that are a consequence of cooperation among individual colony members. One such trait is colony development, which is a consequence of the integration of worker behavior. Results of experimental perturbations [2, 3] suggest that insect colonies cope with constant variation in age demography [4, 5] and resource availability [5, 6] via a process of developmental plasticity that involves ongoing adjustments in the proportions of individual workers engaged in various tasks. The coordination of worker responses to changing environmental conditions is poorly understood. Moreover, the recent discovery [7-9] of genetic influences on the division of labor among workers raises new questions about the role of genetics and the environment in integrating activity in insect societies. Regulation of developmental plasticity is a central issue in the study of all biological systems, and comparisons of processes in insect colonies and individual multicellular organisms may provide insights of general significance . We describe four experiments that probe the hormonal and genetic basis of developmental plasticity in honey bee colonies. The first two experiments demonstrate that changes in colony age structure can affect age-dependent titers of juvenile hormone (JH) that are associated with changes in worker age-dependent behavior (age polyethism). In the third experiment, treatment with a JH analog affected age polyethism, further supporting the hypothesis that extrinsic factors influence the behavior of worker bees via their effects on JH. The fourth experiment demonstrates genotypic differences in the behavioral responses of workers to altered colony age demography. JH, a major insect developmental hormone , is involved in the control of age polyethism in adult worker honey bees [12-16]. Hemolymph levels of JH increase with worker age [13, 17]. Low titers are associated with behavior in the nest such as brood care ("nursing") during the first 1 to 3 weeks of the worker bee's |6-week adult life, whereas a higher titer at about 3 weeks of age induces foraging. We tested the hypothesis  that the JH titer in bees is sensitive to colony state, providing a mechanism for plasticity in age-based division of labor. Workers were exposed to conditions that uncoupled the usually tightly linked factors of worker age and behavioral status for two tasks: nursing and foraging. An association between behavioral status and JH titer, independent of age, would provide support for the hypothesis that JH acts as a colony integrating mechanism. Two colonies, each initially consisting of 2000 bees, 1 to 3 days old, were established to induce division of labor independent of worker age [2, 18]. Within 1 week these "single-cohort colonies" contained some bees that tended brood and others that foraged precociously. The emergence of new adults was prevented by replacing combs of developing pupae with combs of eggs and young larvae from other colonies; the aging experimental colonies then contained "overaged" nurses and "normally aged" foragers. We also exploited demographic changes...
Source Citation (MLA 8 th Edition)
Robinson, Gene E., et al. "Hormonal and genetic control of behavioral integration in honey bee colonies." Science, vol. 246, no. 4926, 1989, p. 109+. Academic OneFile, Accessed 23 Jan. 2019.
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