Land use change and seasonality influence mosquito community composition and disease risk

Anthropogenic land use changes have contributed considerably to the rise of emerging and re-emerging mosquito-borne diseases. Land use and land cover changes produce novel juxtapositions of habitats and species and may result in new interchanges of vectors, diseases and hosts. In tropical Australia, mosquito populations were sampled across an anthropogenic disturbance gradient of grassland, rainforest edge and rainforest interior in both the wet and the dry season.  We captured ~13,000 mosquitoes from 288 trap nights across four study sites. A community analysis of sub-sampled individuals identified 29 species from 7 genera. Mosquito abundance and mean species richness were similar between the three habitats but fewer individuals and species were captured during the dry season. Yet, mosquito community composition varied significantly between rainforest interior and grassland sites in both seasons. Forest edge sites shared a similar community composition with both forest interior and grassland sites. Overall, four mosquito species dominated the samples and showed preferences for either open habitat or forest interiors. Culex annulirostris was the most abundantly captured mosquito across all habitat types and seasons but was significantly more abundant in grasslands, whereas Verrallina lineata and Aedes notoscriptus were captured more frequently in forest interiors than the forest edges and grasslands. Aedes vigilax was most commonly captured in the grasslands and along the forest edges. The findings of this study firstly suggest that the most common and medically important (potential disease-vector) mosquito species (e.g. Cx. annulirostris, Ae. vigilax) are able to breed all year round.  Secondly, that anthropogenic grasslands, adjacent to rainforests may increase the probability of mosquitoes to transmit novel diseases through changes of the vector community on rainforest edges.