Selective adaptation of the cuticular hydrocarbon profiles of the slave-making ants Polyergus rufescens Latr. and their Formica rufibarbis Fab. and F. Cunicularia Latr. slaves

Abstract

The results of comparisons between the cuticular hydrocarbon mixtures of the slave-making ants Polyergus rufescens, their Formica rufibarbis and F. cunicularia slaves and between slave and free-living workers (which were probably related to one another) from each Formica species showed the following. (1) Several products were common to all three species. (2) Each òf the two Formica species had its own particular products. (3) The Polyergus cuticular mixture did not contain any species-specific hydrocarbons but had some components in common with either rufibarbis or cunicularia. Because these products were present in Polyergus, whichever Formica species they enslaved, Polyergus must be able to synthesize their own cuticular hydrocarbons. (4) Cohabitation with another species as the result of slave making had no qualitative effects on the individual cuticular hydrocarbon mixtures: their composition was the same in the Polyergus whether living with F. rufibarbis or F. cunicularia and in the Formica of each species whether free living or enslaved. (5) The Polyergus resembled their Formica slaves, however, due to a tendency to adjust the proportions of some of the common hydrocarbons to those of their slaves; this tendency seems to have been reciprocal, although it was less marked in the case of the Formica. (6) The chemical signatures of mixed colonies inhabited by the same slave species depended mainly on the cuticular characteristics of the Formica slaves but also on those of the Polyergus, which differed from one colony to another. The finding that cuticular hydrocarbon mixtures of individuals of both species (slaves and slave makers) interacting within a mixed colony kept their species-specific hydrocarbons while the proportions of the common products showed a tendency to adapt to those of the other species suggests that there exists a selective mechanism probably involving the regulation of the synthesis of these products.