Age specific acceptance of unrelated conspecifics on nests of the primitively eusocial wasp, Ropalidia marginata

To investigate the possible role of the age of an individual on its acceptance onto unrelated colonies, several individually marked foreign con specifics that had been isolated immediately upon eclosion from their natal nests, were introduced into laboratory cages containing apparently healthy colonies of R. marginata, Foreign conspecifics, if less than or equal to 8 days of age, had a finite probability of being accepted onto unrelated colonies, Young wasps appeared to be accepted preferentially over older ones, both because young individuals made more attempts to join as well as because they met with greater success per attempt, The resident wasps vigorously nibbled and groomed young foreign conspecifics once they were accepted onto nests, just as they did for newly eclosed wasps from their own nests, In both cases, this may result in the transfer of nestmate discrimination odours from mature to young wasps. Three confirmed records of unrelated accepted foreign conspecifics becoming foragers in their foster colonies are presented. We hypothesize that although young foreign conspecifics may be accepted for the proximate reason they may not be efficiently discriminated from newly eclosed nestmates, such acceptance may have an ultimate adaptive value, or at least may not be detrimental to the accepting colony. If the basis of social life is mutualistic interaction among individuals with varying levels of relatedness, as has been postulated for such primitively eusocial wasps, then the advantage of accepting a young foreign conspecific who can be subdued into a subordinate worker role with relative ease, is not difficult to appreciate