LABORATORY STUDIES OF ANT PREDATION ON PARAPATRIC REPTILE TICKS

Two reptile tick species, Aponomma hydrosauri and Amblyomma limbatum, have a parapatric distribution in South Australia. Predation may play a role in maintaining the boundary. Laboratory colonies of Rhytidopone ra and Iridomyrmex ants were collected from near Mt Mary, South Austra lia, close to the tick boundary. They were tested as predators of the two tick species. In the experiments, ticks in leaf litter were more p rotected from predation than those on bare soil. When comparing leaf l itter types from the Mt Mary area, mallee litter was more protective t han bluebush litter of equivalent depth. Ticks positioned at the base of the litter layer were more protected from predation than those at t he litter surface, and Amb. limbatum ticks were more resistant to pred ation than Ap. hydrosauri ticks. These results contribute to our under standing of the mechanisms maintaining the abrupt parapatric boundary between the two tick species. Predators may contribute to preventing t he more susceptible Ap. hydrosauri from spreading further north, where bluebush litter is more common, and so predation risk is higher. Pred ators probably have less influence in preventing Amb. limbatum from sp reading further south.