J. Acarol. Soc. Jpn., 11(1): 37-40. May 25, 2002  The Acarological Society of Japan 37 [SHORT COMMUNICATION] Morphological Studies on the Digestive Tract of Scheloribates azumaensis (Acari: Oribatida) . Satoshi SHIMANO 1 and Tomohide MATSUO 2, 3 1 Department of Upland Farming, National Agricultural Research Center for Tohoku region, Arai, Fukushima city, Fukushima 960-2156, Japan 2 Laboratory of Zoology, Graduate School of Agriculture, Kyushu University, Fukuoka 812-8581, Japan (Received 29 June 2001; Accepted 22 April 2002) Key words: oribatid mite, alimentary tract, chitin-azure, digestion, microanatomy, vital staining INTRODUCTION Oribatid mites play an important role as decomposers in ecosystems. The mites feed and decompose the plant detritus and fungus mycelium on the forest floor. Each species of Oribatida favors different microhabitats (Aoki, 1967) and they have various food habits including phytophagy and fungivory (Luxton, 1972). The activities of oligosaccharases, e. g. chitinase, have been studied to analyze the food habits of oribatid mites (Luxton, 1972; Zinkler, 1972; Zinkler et al., 1986). Since Michael (1884) reported the details of the alimentary tract of oribatid mites, there have been several reports on the morphological characters of the digestive tract of Oribatida (Woodring and Cook, 1962; Smrz, 1989; Smrz and Trelova, 1995; Hubert et al., 1999). Moreover, digestive symbionts with various diges- tive enzyme activities have been found, and the source of the enzymes has also been discussed (Wallwork, 1967; Zinkler et al., 1986). Whether the digestive enzymes of oribatid mites are secreted from their digestive tract or by digestive symbionts is an interesting question. Conclusions have not been obtained yet. In this preliminary study to elucidate the mechanism of digestion, we used light microscopy and a new application of vital staining to visualize how the products of chitin digestion are distributed within the digestive tract of Scheloribates azumaensis Enami, Nakamura et Katsumata, 1996. This species is a potential biological control agent of the fungus Rhizoctonia solani, a soil-borne pathogen that causes radish root rot (Enami and Nakamura, 1996), and our results may help in understanding how the fungus is digested by the mite. MATERIALS AND METHODS Mites: S. azumaensis were originally collected in upland fields in Fukushima Prefecture, 3 Present address: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan アヅマオトヒメダニ消化管の形態学的研究 1 島野智之（〒 960-2156 福島市荒井字原宿南 50 農業技術研究機構東北農業研究センター） 2 松尾智英（〒 812-8581 福岡市東区箱崎 6-10-1 九州大学大学院農学研究科動物学教室 3 現在 : 〒 080-8555 帯広市稲田町西 2 線 13 番地 帯広畜産大学原虫病研究センター）