The Robinson Lab

Social Inhibition of Division of Labor

"What is it that governs here, that issues orders, foresees the future...?"--Maeterlinck, 1927

Division of labor is fundamental to the organization of insect societies, and is thought to be one of the principal factors in their ecological success. Division of labor in insect colonies is characterized by two features: different activities are performed simultaneously, by groups of specialized individuals, which is assumed more efficient than if tasks are performed sequentially, by unspecialized individuals.

A key feature of the division of labor in insect colonies is its plasticity. Colonies respond to changing internal and external conditions by adjusting the ratios of individual workers engaged in the various tasks. This is accomplished in large part via the behavioral flexibility of the individual workers themselves. Worker behavioral flexibility contributes to the reproductive success of a colony by enabling it to continue to grow, develop, and ultimately produce a new generation of reproductive males and females during changing colony conditions.

Sensitivity to change within a structured labor system is important to social organization, but only now is beginning to be understood. The regulation of division of labor relates to one of the central problems in insect sociobiology, colony behavioral integration. Some of the most remarkable traits of social insects, such as their elaborate nests, potent defense strategies, sophisticated techniques of foraging, and intricate but flexible systems of division of labor involve the collective endeavors of perhaps thousands, or even hundreds of thousands, of workers. But it is unlikely that each individual can monitor the state of its whole colony and then perform the tasks that are needed most. In addition, it long has been recognized that highly eusocial insect societies function without a key form of control that exists in human societies. Although workers may play special roles in organizing specific tasks, there is no evidence for the occurrence of colony "leaders", i.e., individuals that perceive all or most of the colony's requirements and direct the activities of other colony members from one task to another. The challenge is to understand the mechanisms of integration that enable workers to respond to fragmentary information with actions that are appropriate to the state of the whole colony.

In most species of highly eusocial insects studied to date, there is age-related division of labor. Adult workers exhibit age polyethism, a form of behavioral development in which they perform different tasks at different ages. Young bees labor in the nest, while older individuals forage outside. During each stage of behavioral development a bee performs more-or-less the same kinds of jobs for a sustained period of time.

Representative Publications

Schulz DJ, Huang Z-Y, Robinson GE (1998) Effects of colony food shortage on behavioral development in honey bees. Behav. Ecol. Sociobiol. 42:295-303. (pdf)

Robinson GE, Huang Z-Y (1998) Colony integration in honey bees: Social control of division of labor. Apidologie 29:159-171.

Pankiw T, Huang Z-Y, Robinson GE, Winston ML (1998) Effects of queen mandibular pheromone on behavioural ontogeny and juvenile hormone titres in honey bees. J. Insect. Physiol. 44:685-692.

Huang Z-Y, Robinson GE (1996) Regulation of division of labor in honey bees via colony age demography. Behav. Ecol. Sociobiol. 39:147-158.

Huang Z-Y, Robinson GE (1992) Colony behavioral integration in honey bees: worker-worker interactions mediate plasticity in hormonally regulated division of labor. Proc. Natl. Acad. Sci. USA 89:11726-11729.