The unusual social organization of the antPachycondyla tridentata (Formicidae, ponerinae)

Abstract

Colonies of the ponerine antPachycondyla tridentata from Malaysia occur with and without queens. In a total of 7 colonies we found more than 80% of the workers to be mated, irrespective of the presence or absence of queens. This is a hitherto unknown social organisation in ants. Queens and workers competed equally for reproduction. In the colonies investigated several ants were laying eggs. Behavioral observations revealed persistent dominance interactions between colony members. A few ants, but not necessarily a queen, occupied top positions. Removal of the most dominant ants led to a new hierarchy in which subordinate ants with developed ovaries were attacked significantly more frequently than non-reproductive ants. On the average, callows were more aggressive than older subordinate ants, displacing most of the older laying workers in one colony. Nestmate recognition tests revealed that non-reproductive ants were much more aggressive towards foreign ants than were ants with developed ovaries.