Mosquito species diversity patterns in an urban environment of Okinawa, Japan

Mosquitoes (Diptera: Culicidae) are highly diverse. In Japan, about two thirds the mosquito species are found in the Ryukyus archipelago, where Okinawa is the largest, most urbanized and densely populated island, and where mosquito species diversity has been more thoroughly studied across the archipelago islands. Nevertheless, in some areas, such as south-central Okinawa, mosquito fauna has been relatively poorly studied. Here, we present results from a systematic study of the mosquito fauna in urban environments of Nishihara city, south-central Okinawa. We sampled mosquitoes biweekly, during a whole year, from three different environments: a forest preserve, a farm, and a water reservoir shore. We employed four mosquito collection methods: Oviposition traps, light traps, net sweeping and treehole and artificial container content suction. We collected a total of 568 adult and 10270 larval mosquitoes belonging to 13 species: Culex pallidothorax, Cx ryukyensis, Lutzia vorax, Lt fuscana, Uranotaenia novobscura ryukyuana, Malaya genurostris, Aedes vexans nipponii, Ae albopictus, Armigeres subalbatus, Anopheles sinensis, Cx bitaeniorhynchus, Cx quinquefasciatus, Cx tritaeniorhynchus; the last six with medical importance. An ecological analysis of species diversity, based on the species accumulation curve, which flattened as expected when sampling has been exhaustive, and the Chao2 (± S.E. = 10 ± 3.7) species richness index supported the comprehensiveness of our sampling. We did not detect changes in species composition when comparing our data with previous studies. Finally, our study highlights the importance of combining several sampling strategies to properly characterize regional mosquito fauna and to monitor changes in the presence of disease vectors.