Honey bees have a complex system of division of labor (DOL) in which bees specialize on discrete task sets as they age. Bees also change strongly in physiology as they age in order to facilitate these behavioral specializations. From a broad evolutionary perspective, social insect DOL systems are highly derived life-history adaptations that use much of the same genetic and hormonal machinery found in the control of juvenile and adult behavior and physiology in other arthropods. Studies of DOL in social insects are thus informative for the general mechanisms by which such life-stage specific behavior and physiology evolve and are controlled because DOL is somewhat more amenable to study than are most ageing processes. DOL is also one of nature’s most complex systems of phenotypic plasticity and is a model system for the study of this topic as well as for the genetic basis of social behavior.
Our work takes an integrative approach that stresses the importance of both detailed behavioral and genomics studies. Our working systems level hypothesis is shown in Fig 1. Colony level needs (for more workers to change caste, for example) are translated into either behavioral or pheromone signals which either affect regulatory genes directly, or via intermediates in the endocrine system. Epigenetic modifications are also likely downstream effects of changes to primer pheromone levels that control DOL. Regulatory genes important for DOL determine caste and tissue specific gene expression patterns which control individual level behavior. The circuit is completed when feedback from the individual affects the colony level behavior of the social group or superorganism. We will be testing this conceptual model using integrative approaches for the foreseeable future.
Future work will also begin to take a more comparative evolutionary approach and include other social and solitary bees.