SPECIES POLYETHISM IN HETEROSPECIFIC GROUPS OF MYRMICINAE ANTS

We studied species polyethism in heterospecific queenless and queenrig ht groups of ants by associating Manica rubida (olygogynous) individua ls with Myrmica rubra (polygynous) and Myrmica ruginodis (monogynous) individuals, respectively. In queenless and queenright groups, Myrmica workers specialized in brood care and guarding the nest while Manica workers performed activities normally reserved for the oldest workers (especially outside activities). This might be due to a more rapid eth ogenesis in workers of the genus Manica. Myrmica workers appeared more plastic in their behaviour and more sensitive to early environment th an Manica workers: their ability to learn was greater, leading them to care for more allospecific brood than Manica workers, who demonstrate d a preference for conspecific brood, in all groups studied. These exp eriments also showed great variability in the expression of species po lyethism among different groups of ants according to the degree of pol ygyny of the queen's species. The behavioural differences observed in Manica and Myrmica species might be due to the phyletic distance betwe en the two genera.