Distribution and seasonal prevalence of Anopheles minimus Theobald (Diptera:Culicidae) in the Yaeyama Island group (except Ishigaki Island), Ryukyu Archipelago, Japan, 1999-2000

In order to know the distribution and seasonal appearance of Anopheles minimus Theobald in the Yaeyama Island group, except Ishigaki Island, a compre hensive larval survey was carried out in Iriomote, Kohama, Hateruma and Yonaguni Islands from 1999 to 2000. Immatures of An. minimus were found in 4 out of 20 habitats examined in Iriomote Island, and 6 out of 13 habitats including streams, springs and ground pools near the springs examined, in Kohama Island. The abundance of the immatures in Hora Stream of Iriomote Island, and a spring of Kohama Island, showed seasonal variation which was positively correlated with water temperature. The immature was not collected during winter season (December to February) in Hora Stream. The density was high in August and October 1999 and June 2000, being 169, 151 and 111 larvae/100 dips, respectively. In the spring of Kohama, the density was 268 in August 1999, and 516 in June 2000. This is the first record of An. minimus for Kohama Island. The immature was not found in Hateruma and Yonaguni Islands.