Cuticular hydrocarbons wherebyMessor barbarus ant workers putatively discriminate between monogynous and polygynous...

The results of laboratory experiments carried out with both monogynous and artificially polygynousMessor barbarus ant colonies (which under natural conditions are always monogynous) have shown that the workers belonging to monogynous colonies were able to discriminate between intruders from other monogynous colonies and those from polygynous (di- and trigynous) ones. What mechanisms are involved in this discriminatory ability? Since differences in the relative proportions of the hydrocarbons they carry are known to convey complex messages that are used for recognition purposes, it was proposed here to investigate whether there existed any differences in the proportions of the various hydrocarbons carried by the diverse categories of intruders tested in our experiments. It emerged that one set of hydrocarbons, which were usually present in rather small proportions and included all the families that constitute this species' chemical signature (n-alkanes, mono-, di-, and trimethylalkanes), was characteristically associated with workers from monogynous colonies. Another set of hydrocarbons, which included some of the above components, mostly in larger relative proportions, can be said to have characterized the digynous and trigynous colonies.