Queen and colony odour in the multiple nest ant species, Cataglyphis iberica (Hymenoptera, Formicidae)

Abstract

We investigated the queen's effect on the cuticular hydrocarbon profile of workers in the monogynous and polydomous species Cataglyphis iberica. Within each of the three colonies tested, workers were separated for three months in queenright and queenless groups. After regrouping, nestmate recognition remained unchanged but the duration of antennal interactions between workers previously separated increased relative to controls. Separated groups presented slightly divergent cuticular hydrocarbon profiles which may induce the longer antennations. A quantitative analysis of major cuticular hydrocarbons showed that the total amount per unit of cuticular surface area remains similar between the two castes; but queens had higher quantities of n-alkanes than workers. The lack of a queen did not affect the workers' cuticular hydrocarbon profile in queenless groups. Indeed, the profile of queenless workers remained significantly different from the queen profile as did that of queenright workers. These results show that queens are not at the origin of the hydrocarbons' colonial profile. Two recognition processes seem to coexist within C.iberica colonies: nestmate discrimination based on the colonial odour which includes all nestmate workers, and a queen caste-specific odour. In a polydomous species such as C.iberica, the queen does not seem to contribute more than any other nestmate to the colonial odour, which probably derives from worker cues, confirming the existence of a "Gestalt" colonial odour.