On the annual prevalence of larvae and pupae of mosquito fauna through a whole year in a suburban area of Setagaya district in Tokyo (Report 3)

Abstract

Successive studies on the seasonal prevalence of larvae and pupae of mosquito fauna in a suburban and residental area of Tokyo city were carried out from May 1961. Results of the year 1961 and 1962 were previously published in this journal (Vol. XII, No. 4 and Vol. XV, No. 4). Examined stations and methods were almost followed as described in the previous paper. Total 37, 493 mosquitoes belonging 3 genera, 6 species were collected (Table 1). C. pipiens occupied 98% and A. albopictus 1.2% and other species less than 0.2% of whole collection. C. pipiens was found in all stations except bamboo stumps and had a tendency to become dominant species even in paddy and swampy field, because of spoiling by residental sewage due to imcomplete drainage system in this area (Table 3〜5). The results of three years 1961〜1963 showed species of mosquito except C. pipiens and C. vorax decrease their number yearly; on the contrary C. pipiens increases constantly and C. vorax fluctuates unstably according to unknown factors. It must be described that between observed numbers of C. pipiens and C. vorax exists obviously antagonistic correlation and therefore C. vorax seems to be useful as natural enemy of C. pipiens in this area (Table 2, comparing with same table in previous papers). C. pipiens and C. vorax appear to be important species to investigate in future in various respects in Tokyo city.