Host and site preferences of water mite larvae attaching to aquatic insects

다국어 초록 (Multilingual Abstract)

The water mites are distributed widely through ponds, lakes and mountain streams. In part of their life cycle, larvae of water mites typically attach on adult aquatic insects including hemipterans, odonates, coleopterans, trichopterans, ephemeropterans, plecopterans and dipterans. Most of the information on hostparasite interactions comes from studies of lentic mites and insects, while relatively little is known about the relationships between lotic mites and insects. The purpose of this study is to elucidate the host-parasite interactions between lotic water mite larvae and host insects in mountain streams. We investigate mite attachment on aquatic insects collected at mountain streams in Kanagawa and Shizuoka Prefectures, Japan. Aquatic insects were collected by light-trap and hand-sweeping from May to August 2008. Aquatic insects were identified to species or genus. The parasitic nature of mite larvae on aquatic insects was examined. The distribution of water mite larvae on host insects was analyzed using the Chi Square Test. As a result, a total of 1716 specimens of aquatic insects representing Megaloptera, Trichoptera, Ephemeroptera, Plecoptera and Diptera were collected. Mites were associated with 31.2% of the total number of aquatic insects. Mite larvae in the genus Stygothrombium were associated with Plecoptera. Protzia larvae were associated with Trichoptera and Diptera. Stygomomonia larvae were associated with Trichoptera. Protzia larvae showed a preference for abdomen of Wormaldia sp. [Trichoptera] (P<0.0001, χ²= 133.3631). Protzia larvae however, showed a preference for prothorax of Antocha sp. [Diptera] (P<0.01, χ²=18.3077). Stygomomonia larvae showed a preference for mesothorax and abdomen of Stenopsyche marmorata [Trichoptera] (P<0.0001, χ²=1147.857). From these results, it is considered that mite larvae show certain host preferences for aquatic insects as well as site preferences for the body parts of host insects.