Relationships of the Ross River virus (Togoviridae: Alphavirus) vector, Aedes camptorhynchus (Thomson) (Diptera: Culicidae), to biotic and abiotic factors in saltmarshes of south-eastern Tasmania, Australia: a preliminary study

Comprehending ecological drivers of mosquito (Diptera: Culicidae) abundance involves a broad appreciation of their abiotic and biotic determinants. Such an appreciation is important where mosquito species cause significant nuisance to humans or are vectors of infectious disease. Here, a preliminary investigation is presented of relationships between larval abundance of the Ross River virus (RRV, Togoviridae: Alphavirus) vector Aedes camptorhynchus (Thomson), in saltmarshes of Tasmania, Australia, to environmental variables, aquatic fauna and surrounding land-use. Surveys of water bodies within six saltmarsh areas were undertaken during relatively stable (dry) environmental conditions, and one saltmarsh was opportunistically re-sampled following a heavy rainfall event. This study was intended to create a baseline of information from which to launch future, more detailed and targeted investigations. Significant relationships between land-use, environmental variables and aquatic fauna among water bodies were found. Abundance of Ae. camptorhynchus larvae was relatively low across sites during dry environmental conditions, but larvae were highly abundant in water bodies at one site following heavy rainfall. Abiotic and biotic correlates (potential determinants) with larval Ae. camptorhynchus abundance differed during these two sampling periods. During dry environmental conditions larvae were negatively related to pH, turbidity, dissolved magnesium, presence of decapods and abundance of amphipods, and positively related to samphire cover. Following rainfall, larval abundance was negatively related to abundance of ostracods. Indirect relationships between land-use and abundance of Ae. camptorhynchus may exist, but more detailed investigations are required to explore this implication.