Studies on the ecology of blackflies (Diptera: Simuliidae) 40. Fauna of the blackflies in Nagano Prefecture in autumn

摘要

The fauna and distribution of blackflies in Nagano Prefecture, Japan, were studied based on the collections of larvae and pupae from streams and adults flying around the collectors at 136 sites in autumn of 1997. A total of 20,735 black-flies, 18,232 larvae (87.9 percent in total number), 2,492 pupae (12.0 percent) and 11 adults (0.1 percent), were collected at 131 sites. All these blackflies were classified into 19 species of two genera: Prosimulium Roubaud and Simulium Latreille. Four species, Simulium (Nevermannia) aureohirtum, S. (Simulium) quinquestriatum, S. (Gnus) nacojapi and S. (Eusimulium) sp. H were newly recorded from Nagano Prefecture. The most abundant species was S. (S.) japonicum (27.4 percent in total number), followed by S. (S.)kawamurae (17.6 percent), S. (Odagmia) aokii (17.3 percent), S. (N.) uchidai (14.9 percent), S. (O.) iwatense (10.1 percent) and S. (Gn.) bidentatum (5.6 percent). The most widely distributed species was S. (S.) japonicum (77 sites), followed by S. (N.)uchidai (71 sites), S. (O.) aokii (58 sites), S. (S.) suzukii (51 sites), S. (S.) kawamurae (44 sites), S. (Gn.) bidentatum (33 sites), S. (O.) iwatense (30 sites) and S. (N.) subcostatum (26 sites).