A study on the Aedes togoi to find out important biological and ecological factors as an efficient vector of filariasis, was carried out on Che-Ju Island for two years from 1968 though 1969. Results obtained are as followings: Geographical distribution of the mosquito breeding habitat was found to be extensive covering circular areas of about three km distance along the shore line. The main breeding sites were rockpools and smaller holes on rocks retaining tide and/or rain water with high larval density; water tanks, pots, and other artificial containers retaining only rain water around the houses located within the area with relatively low larval density. Species constitution of adult mosquitos collected in the study villages consisted largely of Aedes togoi with a range of 70-90 per cent by village. The pH of the breeding sites ranged from 5.0 to l0.0, and the chloride content from 0.01 to 28.75 (gm/l). More than fifty per cent of examined sites, however, had pH 5.6-6.5 and chloride content of less than 1.0 gm/1. The natural infection rate of A. togoi by filaria showed proportional relationships with microfilaria rates among the human population by area. Experimental infection of A. togoi by human and dog filaria demonstrated that this species is an efficient vector for both filaria species proved by natural infection as well as experimental infection. Susceptibility of both larva and adult of A. togoi to insecticide, DDT and dieldrin, showed considerable sensitivity in all villages tested.
