Boundaries and bacteria – identifying the mechanism for a parapatric boundary between two tick species

By 05/09/2019Current Projects
HSF 19059 | Amount: $85,233 | Project Leader: M Gardner | Project Period: Jul ’19 – Jul ‘22

A project undertaken at Flinders University, and supervised by Mike Gardner.

Sleepy lizards (Tiliqua rugosa) in the mid north of South Australia have been monitored in a continuous conservation survey for the past 38 years. Two species of parasitic reptile ticks have been identified in the area and their ranges abut at a sharp 1-2km boundary. Bothriocroton hydrosauri ticks are found south of this boundary while Amblyomma limbatum ticks are confined to the north.

Climatic factors and predators prevent the B. hydrosauri ticks from moving north but long-term research has not uncovered why A. limbatum does not exist further south. It has been hypothesised that pathogens, particularly Rickettsia bacteria from the yellow spotted fever group, may be responsible for maintaining the parasite boundary. The current project will gain preliminary data to explore this possibility.

Associate Professor Mike Gardner and his team will examine the distribution and what species of Rickettsia occurs near Mount Mary in South Australia. They will determine if, and how, Rickettsia is transferred from B. hydrosauri and whether this results in mortality of A. limbatum

This research will reveal whether Rickettsia is involved in maintenance of the parasite boundary between B. hydrosauri and A. limbatum ticks and increase understanding of how climate may influence the spread of disease.

The project also allows the unbroken continuation of the long-term surveys started by the late Mike Bull in 1982. This valuable resource has provided some of the most detailed information available on wildlife host-parasite interactions.