Conservation and structure of the aquatic insect communities on various conditions paddy field areas in Ina Basin, Nagano Prefecture

Recently, decreases and changes in aquatic insect communities at paddy field area are becoming an important problem to conserve biological diversity. Therefore, the purpose of this study was to know relationship between aquatic insect communities in paddy field area and environmental conditions. We selected finally eight various condition study areas (two con-consolidated paddy areas in hilly and mountainous areas, two consolidated paddy area in hilly and mountainous area, tow non-consolidated paddy areas in urbanized area, two consolidated paddy area in urbanized area) in the Ina Basin, Nagano Prefecture. The survey of aquatic insect communities was carried in 6 times per year from 2011 to 2012 in all study areas. The number and taxon name were recorded by capture method. All study areas were classified into 4hilly and mountainous area region and 4 urban areas by TWINSPAN. Aquatic communities were classified to six types. Each community type corresponded different environmental conditions of urbanization, and forest and others, and consisted of characteristic species. It seemed that we must maintained each environmental condition to conserve each community type. On the other hand, It was pointed out that the mid-summer drainage management decreases the population of the aquatic insect in the middle of summer.