名古屋地方における蚊族個体群の発生動態 : VI. アカイエカの越冬個体群における長翅群および短翅群の割合

Abstract

An ecological study was made on the overwintering populations of the house mosquito, Culex pipiens pallens, in 6 caves of 3 localities in Aichi Prefecture (Fig. 1), central Japan, during the period from October 1969 to March 1970. Female mosquitoes captured were C. p. pallens (Cpp), C. hayashii, C. orientalis, C. vorax and Anopheles sinensis in order of decreasing numbers (Table 1). Overwintering females of Cpp appeared on the inside walls of the caves in October, became most abundant in January of the following year and decreased toward March. Monthly fluctuation patterns in catch size of the mosquitoes were similar to those obtained separately by counting without removal (Fig. 2). Wing length distribution of the overwintering Cpp females did not show the normal distribution, whereas that of field-collected summer populations proved to be the normal one (Fig. 3). Using probability paper analysis, the overwintering populations were found to be composed of two different groups with regard to wing length; one was a long-winged group which accounted for about 90% of the populations and the other was a short-winged group (Figs. 4,5 and Table 2). Similar phenomenon had been observed in the same localities in the previous year (Makiya et al., 1971). In order to know closely whether autogenous C. p. molestus (Cpm) were intermixed with the overwintering anautogenous Cpp populations, discriminant function derived from 5 characters was applied to differentiate the two biotypes. As a result, most of the ovewintering females were identified as Cpp, but a few individuals (8∿10%) were morphologically regarded as Cpm. The overwintering short-winged group, however, seemed not be Cpm, because wing length of most of the individuals regarded as Cpm fell within the range of the long-winged group (Table 3 and Figs. 4,5).