Cognition across castes: individual recognition in worker Polistes fuscatus wasps

In many signalling systems, intraspecific variation in recognition abilities is based on developmental stage, experience or caste. However, the occurrence of intraspecific variation in recognition has not been thoroughly examined in species with individual recognition. For example, previous work has shown that individual recognition is an important aspect of the social life of Polistes fuscatus (paper wasp) nest-founding queens, as individual recognition stabilizes dominance interactions and reduces aggression. To date, the potential for individual recognition among P. fuscatus workers has been largely ignored. Here, we explore whether there is intraspecific variation in individual recognition by testing P. fuscatus worker recognition abilities in a series of staged contests. The results indicate that P. fuscatus workers are capable of individual recognition: focal workers paired with previously encountered partners experienced significantly less aggression and more nonaggressive bodily contact than focal workers paired with unknown social partners. We propose two potential explanations for individual recognition among workers: (1) worker individual recognition may be favoured because it provides social benefits to workers, or (2) worker individual recognition may be a byproduct of selection for individual recognition in foundresses. Individual recognition is often considered a cognitively challenging form of recognition, so future studies that compare the sophistication of recognition across castes will be useful to assess whether there are more subtle differences in cognitive abilities or recognition behaviour between P. fuscatus nest-founding queens and workers.