Nonnestmate kin recognition in the ant Leptothorax lichtensteini: evidence that genetic factors regulate colony recognition.

Young monogynous colonies of Leptothorax lichtensteini showed completely unaggressive behavior toward unfamiliar kin-related workers which were experimentally introduced into their nest, whereas they were much more hostile toward nonrelated workers (42% of which were rejected). During the first 30 min of observation, related intruders received significantly more licking and participated in a significantly greater number of trophallactic exchanges than nonrelated ones. These experiments show clearly that genetically determined chemical cues are involved in colony recognition. The mechanisms whereby these factors contribute to kin recognition are discussed, and it is concluded that phenotype matching may be the main process involved.