The role of age in temporal polyethism in a primitively eusocial wasp

Abstract

The relation of age to division of labor was assessed in a primitively eusocial wasp, Ropalidia marginata. The performance of four functionally significant tasks was analyzed. It was found that age has a definite correlation with division of labor, since wasps performed tasks in a distinct sequence in their life with successive tasks being initiated at significantly older ages. Age of a wasp was measured in absolute terms and also relative to other individuals in the colony. Probability of performance of a given task relative to other tasks (PTP) and absolute rates at which tasks were performed per unit time (FTP) both showed clear age-dependent patterns, confirming the association of age with division of labor. The proportion of variance explained for both PTP and FTP was significantly higher with relative age than with absolute age. Interindividual interactions were found to be a potential mechanism through which wasps can determine their relative age. The advantages of work organization depending on relative age and the constraints imposed by absolute age are discussed.