横浜市街地におけるアカイエカおよびチカイエカの捕獲状況と季節変化  [in Japanese] Seasonal abundance of Culex pipiens pallens and Culex pipiens molestus collected with dry-ice light traps in urban Yokohama  [in Japanese]

Culex pipiens complex mosquitoes were collected to clarify their geographical distributions and seasonal abundance in urban Yokohama. Dry-ice light traps were set to collect adult mosquitoes in three residential districts from March 2006 to January 2008. Culex pipiens complex was classified into two subspecies, C.p. pallens and C.p. molestus by counting the number of individual eyes in the fifth line of the adult female compound eyes and measuring the D/V ratio of the adult male genitalia. In Naka ward, 72.5% of the adult female C.p. complex was determined to be C.p. molestus in 2006, whereas 65.3% (417/639) was determined to be so in 2007. However, the ratios of C.p. molestus among the male C.p. complex captured in Naka ward were 12.3% in 2006 and 9.3% in 2007. In Minami ward, the number of captured males was so small that the identification of the two subspecies was obtained only for the females; the result indicated that the ratio of C.p. molestus was 32.2% in 2006 and 25.7% in 2007. In the Institute of Health (Isogo ward), where insect were collected in the yard, 23.8% of the females and 5.9% of the males were C.p. molestus in 2006, whereas 13.5% of the females and 2.4% of the males were C.p. molestus in 2007. This suggested that the distribution of the adult females should also be identified for precise monitoring, since there appeared to be too few adult males in some districts.