北海道日高地方の馬産地におけるアブ類の生態に関する研究 : 2. 幌別川流域におけるアブ類の発生源, 種構成および季節消長

Abstract

Breeding sites, species composition and seasonal prevalence of tabanid flies were studied along the basin of the Horobetsu River, Hokkaido in 1976 and 1977. The adult flies were collected with CO_2-lured mosquito-net traps which were set at 3 sampling sites along the midstream of the river from early July to middle September. Larval collections were made at their suspective breeding habitats. Aquatic or semi-aquatic breeding sites yielded 10 species of larvae, of which 5 were from streams, 2 from ponds, and 7 from paddy fields. Terrestrial breeding sites yielded 5 species of larvae, of which 5 were from grasslands, and 3 from forests. Eighteen species were collected by the survey of adults. Tabanus nipponicus was the predominant species occupying 56.3% of the total flies, followed by T. chrysurus (15.0%) and T. trigonus (6.2%). Abundant occurrence of T. trigonus at an area was unusual for Hokkaido. The tabanid fauna of the surveyed area was similar to those in the Oshima Peninsula, Hokkaido, and the Tohoku District, Honshu. The number of species and individuals of tabanid flies in the surveyed area was most abundant in August. Seasonal prevalence of Hirosia sapporoensis, T. trigonus and T. katoi was observed for the first time in Hokkaido.