The mosquito fauna of K'Gari (Fraser Island), Australia, the world's largest sand island

Abstract

K'gari (Fraser Island) is the largest sand island in the world and a popular tourist destination. Despite its importance as a United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage Site, there is a paucity of information regarding its mosquito fauna. From 1968 to 1976, several qualitative entomological surveys were carried out on K'gari, but no published work has been undertaken since. This study presents quantitative findings from three surveys undertaken using CO2-baited light traps in April and October 2024, and May 2025. In total, 3,356 mosquitoes, representing 31 species across 10 genera, were collected from 28 sites. Ten of these species were previously unrecorded on K'gari including Culex gelidus, a known vector of Japanese encephalitis virus (JEV). The major Australian arbovirus vector, Culex annulirostris, was the most prevalent species recorded overall, comprising 22% of mosquitoes collected. Considerable numbers of Mansonia uniformis and Coquillettidia spp., whose larvae develop in freshwater sites with emergent vegetation were also observed, along with high abundances of other freshwater species. Surprisingly, species associated with brackish habitats, such as Aedes vigilax and Culex sitiens comprised < 5% of the total species collected. Relatively large numbers of Culiseta arenivaga, a species that has only ever been recorded from K'gari were also observed. Overall, it is evident that K'gari is home to an abundance of diverse and medically important mosquito fauna, with assemblages dominated by freshwater-associated species, rather than coastal salt marsh taxa.