POLYETHISM WITHIN HUNTERS OF THE PONERINE ANT, ECTATOMMA-RUIDUM ROGER(FORMICIDAE, PONERINAE)

During laboratory experiments, two categories of prey-foraging workers were found in Ectatomma ruidum: stingers and transporters. When numer ous live drosophila were offered to the ants, one group of hunters spe cialized in killing the prey and another in transporting simultaneousl y the dead drosophila to the nest. Sometimes, there was a transfer of prey by a stinger towards a transporter, after an active soliciting of the transporter by antennation or by using the forelegs. We found hig h positive correlations between the colony size and the number of ants in each subcaste. A negative correlation existed between the colony s ize and the proportion of hunters. However, the proportion of workers in the two behavioral subcastes of hunters was stable in spite of diff erences in colony size. The phylogenetic interest of this type of coop erative predation is discussed.