Nesting and food resources of syntopic species of the ant genus Polyrhachis (Hymenoptera, Formicidae) in West-Malaysia

Polyrhachis is one of the largest ant genera in the world distributed in th e Old World tropics and subtropics. We investigated the nesting and nutriti on habits of 10 syntopic species of Polyrhachis in West-Malaysia. Striking differences between these species exist in regard to the nesting habits. Ou r research revealed four different nest types (soil nests, nests in preform ed cavities, nests constructed of dead vegetative and soil particles, silk nests). The utilization of silk for nest construction expands the nest dive rsity of Polyrhachis considerably (nests in preformed cavities with silk su pplement, pure silk nests, silk nests reinforced by dead vegetative and soi l particles). In regard to nutrition habits of Polyrhachis two major modes were found: Th e tending of trophobionts and the opportunistic exploitation of sugary reso urces. The trophobiotic species keep their trophobionts inside the nest, in side pavilions, openly exposed and guarded or not guarded by the workers. S pecies of this group are characterized by large colonies and highly efficie nt recruitment systems. They defend food sites and sometimes establish terr itories. The non-trophobiotic species have small colonies, mostly less effi cient recruitment systems and do not establish territories or defend food s ites. Thus in the genus Polyrhachis nesting habits as well as nutrition hab its seem to be key factors allowing the coexistence of so many different sp ecies.