Author(s): Kota Tawa; Shiro Sagawa
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Abstract: The Toyooka Basin located in Hyogo, Japan, is a major base for the reintroduction of the Oriental white stork Ciconia boyciana. Fallow field biotopes, which are artificial wetlands in paddy areas, have been created as habitats for lentic aquatic animal communities and as feeding sites for storks in the Toyooka Basin. We studied the effect of the fallow field biotope on the habitat of Odonata, Hemiptera, and Coleoptera taxa, which are the predator and indicator fauna in paddy fields, and compared it with that of paddy fields. Abundance s of some adult diving beetles, such as Graphoderus adamsii, Hydaticus grammicus, Rhantus suturalis, and Cybister brevis, increased drastically in August in the fallow field biotope. However, their larvae were mainly captured in paddy fields around the fallow field biotope during the reproductive season, whereas they were rarely seen in the biotope. Surface water is lost in paddy fields after August for rice harvest; therefore, we speculated that adult beetles must have migrated in the biotope. Although some larval Odonata taxa (e. g., Orthetrum, Anax, and Zygoptera) appeared at both the paddy fields and the biotope, Sympetrum larvae, the indicator taxa of paddy fields, were only observed in the paddy fields. The population numbers of the water stick insect, Ranatra chinensis (Hemiptera) dramatically increased in the deep -water area of the biotope in October. These results suggested that the fallow field biotope had different aquatic insect communities than those in the paddy fields and the fallow field biotope acts as a refugium habitat for aquatic insects during the paddy field drainage season. Therefore, it is presumed that fallow field biotopes would greatly improve the diversity of aquatic insects in paddy field areas.
Year: 2018