Landscape ecological analysis of spatial distribution of biting Anopheles minimus

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We conducted a 2 years survey on An. minimus, a malaria vector, and their habitats on Ishigaki Island, which is situated close to the subtropics and the northern limits of the distribution of the species. To clarify difference in the spatial distribution of local mosquito populations in relation to characteristics of their habitats, a landscape ecological approach was considered. Sampling efforts consisted of CDC light-trapping enhanced by 500g dry ice, human baited collection, larval collection by dipping, and more than 1,000 photographs, were taken from more than 19 locations in the study area ranging 10km x 3km. The photographs were digitized and the density of tree, the proportion cover of grasses, bushes and shrubs and canopy were estimated. Components of ground surface also were quantitatively identified. In addition to the photograph analysis, NDVI and other parameters calculated from 24 satellite images were taken into account to classify and to characterize the habitats more precisely. A database analysis of mosquito density combined with habitat characteristics using the factor analysis of principal components' enabled us to explain the distribution of mosquitoes in the area from a landscape ecological perspective. An. minimus was abundant at locations not far from breeding sites, and where the canopy cover was not so dense.