The reproductive division of labour but not worker age affects spatial sorting within the nest in a paper wasp

摘要

Spatial behaviour of colony members within a nest represents an essential aspect of colony organization. However, little attention has been devoted to the study of this aspect in social insects. A recent study based on a single day of observation showed that colony members of the paper wasp Polistes dominula were spatially arranged on the comb in a predictable way. Alpha females patrolled a small central area of the comb, while subordinates and workers were mostly active in the nest periphery. The present study investigated the existence of a spatial-temporal polyethism in P. dominula by studying whether workers and foundresses change their within-nest spatial behaviour over their lifespan. The results showed that while the age of a worker weakly influenced the probability that she performed a within-nest task or foraged outside, it did not account for any aspect of the wasp's within-nest spatial behaviour. Precisely, the size of the patrolled area, the position on the comb, and the rate of superimposition with other nestmates were all not related to the age of the wasp. Moreover, no evident spatial segregation between young and old individuals occurred on the comb. These findings suggest that other proximate mechanisms underlie the observed colony spatial organization. As the reproductive division of labour was the only factor affecting wasp spatial sorting within the nest, dominance hierarchy and social interactions between and within foundress and workers represent good candidates responsible for the colony's spatial organization.