Occurrence of blackflies and plans for their control in the upper reaches of the Ukawa River in Kashiwazaki City, Niigata Prefecture, Japan. 1. Focus on distribution of blackfly larvae

Abstract

In order to control adult blackflies in the upper reaches of the Ukawa River in Kashiwazaki City, Niigata Prefecture, the present study was conducted on the larval habitats of blackfly at a total of 128 sites (a total of 319 sampling times) around the river, small stream and the waterway in the upper reaches of the Ukawa River Basin from June to October in 2013. A total of 12,805 individual blackfly larvae and pupae were captured during the investigation periods. The average number of larvae per site was 40.1 individuals/two investigators·5 minutes and we could collect blackfly larvae and pupae at almost all sampling sites. Noda was the highest capture area where we could collect 51.6 individuals/two investigators⋅5 minutes, followed by the Joujou Area. The fewest captures were in the Betsumata Area (19.5 individuals/two investigators⋅5 minutes). The dominant species was Simulium (Simulium) bidentatum (Shiraki, 1935) (279 total individuals, 34.8%), followed by Simulium (Simulium) quinquestriatum (Shiraki, 1935)(225, 28.1%), and Simulium (Simulium) japonicum Matsumura, 1931 (101, 12.6%).