Disentangling environmental and heritable nestmate recognition cues in a carpenter ant.

Discriminating between group members and strangers is a key feature of social life. Nestmate recognition is very effective in social insects and is manifested by aggression and rejection of alien individuals, which are prohibited to enter the nest. Nestmate recognition is based on the quantitative variation in cuticular hydrocarbons, which can include heritable cues from the workers, as well as acquired cues from the environment or queen-derived cues. We tracked the profile of six colonies of the ant Camponotus aethiops for a year under homogeneous laboratory conditions. We performed chemical and behavioral analyses. We show that nestmate recognition was not impaired by constant environment, even though cuticular hydrocarbon profiles changed over time and were slightly converging among colonies. Linear hydrocarbons increased over time, especially in queenless colonies, but appeared to have weak diagnostic power between colonies. The presence of a queen had little influence on nestmate discrimination abilities. Our results suggest that heritable cues of workers are the dominant factor influencing nestmate discrimination in these carpenter ants and highlight the importance of colony kin structure for the evolution of eusociality.