MEAT ANTS AS DOMINANT MEMBERS OF AUSTRALIAN ANT COMMUNITIES - AN EXPERIMENTAL TEST OF THEIR INFLUENCE ON THE FORAGING SUCCESS AND FORAGER ABUNDANCE OF OTHER SPECIES

Meat ants (Iridomyrmex purpureus and allies) are perceived to be domin ant members of Australian ant communities because of their great abund ance, high rates of activity, and extreme aggressiveness. Here we desc ribe the first experimental test of their influence on other ant speci es, and one of the first experimental studies of the influence of a do minant species on any diverse ant community. The study was conducted a t a 0.4 ha savanna woodland site in the seasonal tropics of northern A ustralia, where the northern meat ant (I. sanguineus) represented 41% of pitfall catches and 73% of all ants at tuna baits, despite a total of 74 species being recorded. Meat ants were fenced out of experimenta l plots in order to test their influence on the foraging success of ot her species, as measured by access to tuna baits. The numbers of all o ther ants and ant species at baits in exclusion plots were approximate ly double those in controls (controlling for both the fences and for m eat ant abundance), and returned rapidly to control levels when fences were removed after 7 weeks. Individual species differed markedly in t heir response to the fencing treatment, with species of Camponotus and Monomorium showing the strongest responses. Fencing had no effect on pitfall catches of species other than the meat ant, indicating that th e effect of meat ants at baits was directly due to interference with f oraging workers, ana not regulation of general forager abundance. Such interference by meat ants has important implications for the sizes an d densities of colonies of other ant species, and ultimately on overal l ant community structure.