Behavioural assays testing the appeasement allomone of<i>Polyergus rufescens</i>queens during host-colony usurpation

Abstract

The role of decyl butyrate (the main component of the secretion of Dufour's gland in newly-mated queens) during host-colony usurpation was investigated in the European amazon ant Polyergus rufescens. The effect of this ester on the behaviour of workers of the common host species Formica cunicularia was analysed. We used a laboratory aggression test during which workers of the species Camponotus ligniperda, masked with synthetic decyl butyrate, were introduced into colony fragments of F. cunicularia. The results showed that this compound drastically lowers the degree of overt aggression against the introduced ants, and we suggest that it acts as an appeasement allomone. Moreover, pieces of filter-paper soaked with decyl butyrate were more attractive than pieces of paper treated with solvent. The results are discussed in relation to a chemical strategy that likely allows an easier invasion and usurpation of host colonies by queens of this obligatory slave-making ant.