Recruitment behavior in the ant genus Polyrhachis (Hymenoptera, Formicidae)

We present a detailed behavioral analysis of the signals involved in recruitment of 11 syntopic Polyrhachis species from West Malaysia. We found a considerable variety of recruitment techniques, including "social carrying behavior," "tandem running," "group recruitment," and a technique which we call "leader-independent trail communication." The latter mode superficially resembles "chemical mass communication" (sensu Wilson, 1962). All these recruitment techniques involve mechanical invitation behavior inside the nest, comprising back-and-forth jerking or pulling movement often combined with a sideways waggling. However, not in all cases of leader-independent trail communication is a mechanical invitation behavior obligatory. The trail pheromone of all investigated Polyrhachis species originates from the hindgut. Only in the tandem running P. proxima do additional secretions from the poison gland appear to be involved in tandem calling.