The influence of the queen, colony size and worker ovarian development on nestmate recognition in the ant Rhytidoponera confusa

Colonies of the ant Rhytidoponera confusa commonly occur naturally both with (queenright) and without queens. (Queenless colonies contain reproductive workers.) Both queenright and queenless colonies showed highly significant kin discrimination ability. Furthermore, 10 assays from four different experimental designs all showed no significant difference in discrimination ability between the two colony types. Aggressiveness and discrimination ability were not correlated with colony size in nine of the 10 assays. The tenth assay showed a significant positive correlation. Aggression towards nestmates maintained with individual alien conspecific queens for 4–7 weeks was no different from that towards nestmate controls but was significanly less than aggression towards non-nestmates. These results suggest that the queen is not the major source of the colony odour in this species. Aggression between reunited queenright and queenless fragments of the same colony in R. confusa is directed towards those nestmates in the queenless fragment with especially well-developed ovaries. Hence ovarian development probably explains such aggression better than interpretations by other researchers that the aggression is evidence for the queen producing the colony odour.