THE UNUSUAL SOCIAL-ORGANIZATION OF THE ANT PACHYCONDYLA-TRIDENTATA (FORMICIDAE, PONERINAE)

Colonies of the ponerine ant Pachycondyla tridentata from Malaysia occ ur with and without queens. In a total of 7 colonies we found more tha n 80% of the workers to be mated, irrespective of the presence or abse nce 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 r evealed persistent dominance interactions between colony members. A fe w ants, but not necessarily a queen, occupied top positions. Removal o f the most dominant ants led to a new hierarchy in which subordinate a nts with developed ovaries were attacked significantly more frequently than non-reproductive ants. On the average, callows were more aggress ive than older subordinate ants, displacing most of the older laying w orkers in one colony. Nestmate recognition tests revealed that non-rep roductive ants were much more aggressive towards foreign ants than wer e ants with developed ovaries.