Generic Composition of Scelionidae (Hymenoptera) in Agricultural Lands

Abstract

All species of the Scelionidae (Hymenoptera) are the egg-parasitoids of insects or spiders, and some of them are important for pest control. In Japan, 33 genera and 70 species of the family were recorded, but I presume a few hundred species are distributed in the country. The faunal survey of parasitic wasps in agricultural lands is important to utilize them for insect pest management and to investigate their biodiversity in "Satoyama". This is the first report on a generic composition of Scelionidae in the Tokai district, Japan. To collect insects, Malaise traps, emergence traps, and yellow pan traps were set in various farms, paddy fields, fallow fields, and riverbanks. These traps were also set in secondary summer-green forests to compare with the scelionid fauna in agricultural lands. In this study, about ten thousand specimens were examined, and 34 genera of Scelionidae were identified. The ratios of scelionid specimens to parasitic Hymenoptera in agricultural lands were larger than those in forests. The number of genera in agricultural lands was more than that in forests. Moreover, most of genera caught in agricultural lands held a lot of individuals. Therefore, the biodiversity of Scelionidae in agricultural lands is not less than that in forests. It is assumed that the richness of Scelionidae in agricultural lands is caused by the abundance of grasshoppers and crickets, which are the hosts of most of Scelionidae.