Abstract
The diversity of carnivorous aquatic insects (Coleoptera; Hemiptera) is declining with changes in the rice paddy environment. Environmentally friendly farming methods that reduce the use of pesticides and herbicides are gaining attention as effective conservation methods. However, little is known about how environmental factors other than farming practices affect aquatic insect communities. Here, we investigated the effects of multiple factors on aquatic insect communities at the individual rice paddy and landscape levels. The results showed that the taxon richness of aquatic insects increased with prey abundance and water temperature, but decreased with conventional farming practices. The landscape between 2,000-3,000 m best explained the taxon richness and the abundance of aquatic insects. The ratio of water area excluding paddies (ponds, fallow paddies, and rivers) had a positive effect on the taxon richness of aquatic insects, whereas the proportion of rice paddies had a negative effect. We suggest that a stable prey supply and the management of water areas and forests are needed to conserve aquatic insects, in addition to promoting environmentally friendly farming.
