Available kin recognition cues may explain why wasp behavior reflects relatedness to nest mates

It is often suggested that social insects cannot discriminate among their nest mates on the basis of kinship because the necessary olfactory cues are simply not available. In contrast, here we find that reliable kinship cues are present in the paper wasp Polistes dominulus. However, genetic relatedness itself was a better predictor of helping behavior and competitive behavior than kinship cues, suggesting that wasps use only a small portion of the olfactory signal to judge whether they are close relatives of their nest mates.Relatedness is predicted to be a key determinant of cooperative behavior, but kin discrimination within social insect colonies is surprisingly rare. A lack of reliable cuticular hydrocarbon (CHC) cues is thought to be responsible, but here we show that in a high-profile paper wasp model, kin recognition cues are available for some individuals that found nests with nonrelatives. Thus, unrelated Polistes dominulus helpers could potentially recognize themselves as such. On this basis, we reanalyzed a behavioral data set to investigate whether foraging effort, defense contributions and aggression toward nest mates might thus reflect CHC profiles. Both foraging behavior and aggression varied with genetic relatedness, but genetic relatedness itself was a better predictor of this variation than differences in CHC profiles. We propose that wasps use specific components of the CHC profile, the identity of which is as yet unknown, to identify relatives among nest mates. Our data provide the first evidence of within-nest kin discrimination in primitively eusocial wasps but leave open the question of which cues are responsible.