The function of dart behavior in the paper wasp, Polistes fuscatus

Abstract

Dominance behavior in Polistes wasps is a composite trait consisting of various discrete behaviors such as darts, lunges, bites, and mounts. The majority of these behaviors are considered ‘aggressive’, and these aggressive behaviors are considered to form a continuum from mild (e.g., darts) to severe (e.g., falling fights). In this paper we focus on darts, the most common of the dominance behaviors, and investigate their function in un-manipulated post-emergent colonies of the primitively eusocial wasp P. fuscatus. Here we show that darts are correlated with the more severe dominance behaviors, and that dominance ranks do not change with the addition or exclusion of darts. We find no correlation, however, between receiving darts and receiving more severe dominance behaviors. This result suggests that darts are not indicative of aggressive reinforcement of dominance, but rather may serve a different function. Our data suggest that the function of darts is to regulate activity on nests. Both foundresses and workers dart inactive workers significantly more often than by chance, and workers respond to a foundress’s (but not a worker’s) dart by becoming less inactive. We also found that active workers who receive a dart from either a foundress or worker respond mostly by switching from one activity to another. Thus, our data suggest that darts are not aggressive behaviors, that foundresses use this signal to initiate activity, and that foundresses and workers both use the signal to regulate worker activity.