Proximate mechanisms of age polyethism in the honey bee, Apis mellifera L.

Abstract

Workers in most insect societies exhibit a division of labor known as age polyethism, so named because workers tend to perform different tasks at different times in their lives. The most common explanation for this phenomenon involves a weak causal link between a worker's age and its occupation. However, available estimates of age effects are generally confounded with other sources of variability. Further, there is considerable variation in the age at which each task is performed. Consequently, the role of age in division of labor remains unresolved. An alternative model, christened 'foraging-for-work', explains age polyethism without a causal link between age and occupation. The specific algorithm, however, is too restrictive to apply in many task situations, and it is inconsistent with existing data on how workers actually locate and select tasks in certain contexts. Therefore, it cannot serve as a general model for task location/selection or for age polyethism. The model's conceptual basis, however, that an age-neutral mechanism can generate age polyethism, is an important contribution that demands further study. The current dialogue over proximate mechanisms of age polyethism has helped to clarify the pattern of behavioral ontogeny in honey bees. A conservative interpretation of existing data is that behavioral ontogeny is characterized by a nest phase followed by a foraging phase. The timing of the transition between these phases is determined more by the environment and physiological processes than by age. Whether nest tasks also follow a necessary sequence is less certain and requires further study.