Selective Acceptance of Alien Host Species Pupae by Slaves of the Dulotic Ant,Harpagoxenus sublaevis (Hymenoptera,Formicidae, Myrmicinae)

The European slave-making ant, Harpagoxenus sublaevis, has up to three host species which occasionally are found all together in one colony. Colonies with only Leptothorax acervorum slaves, or with both L. acervorum and L. muscorum, are frequent, whereas colonies with only L. muscorum slaves are rare, although young H. sublaevis queens found their colonies about equally frequently with either of the two main host species. We demonstrate here, that the two host species exhibit an asymmetric acceptance behavior towards each other's pupae: L. muscorum workers accept L. acervorum pupae, both in non-enslaved colonies and as slaves in H. sublaevis nests, whereas L. acervorum never accepted L. muscorum pupae. Origin and meaning of this behavioral difference are unknown. The findings, however, might be very important with respect to host specificity and host-parasite interactions also in other slave-making ants.