Genetic polyethism and nest building in the weaver ant Oecophylla smaragdina (FABRI-CIUS, 1775) (Hymenoptera: Formicidae)

Abstract

The division of labour, i.e., the specialisation of workers on certain tasks, is a very prominent feature of eusocial insect colonies. Internal factors like physiological state and genetic makeup can influence the task an individual chooses to under-take. We examined nest construction in the weaver ant Oecophylla smaragdina (FABRICIUS, 1775) to explore the relationship between colony genetic diversity and division of labour. Single nests were collected from each of five colonies of this species in Townsville, Australia, and individually placed on small citrus trees. Nest reconstruction was elicited by displacing the walls of the transferred nest and the subsequent behaviour of workers classified into seven categories, three of which involved nest-construction activities. Workers were collected in approximately equal numbers from each behavioural group (equalling an average of 107 workers per colony) and identified to patriline using five microsatellite markers. All colonies contained only a single queen (monogynous). Three colonies were effectively monandrous while two colonies were polyandrous with the number of patrilines per colony ranging between 2 and 3. Genetic polyethism in nest-construction behaviour was detected only in the colony with three patrilines, with individual patrilines engaging in particular building activities more frequently than expected by chance alone. These results indicate that a genetic impact on the division of labour may influence the task choice of workers, though a larger study is necessary to determine the prevalence of this influence in O. smaragdina.