Suppressive Effect of <i>Euseius sojaensis</i> or <i>Amblyseius eharai</i>（Acari: Phytoseiidae）on <i>Tetranychus kanzawai</i>（Acari: Tetranychidae）on Japanese Pear

Five phytoseiid mite species: Phytoseiulus persimilis Athias-Henriot, Neoseiulus californicus（McGregor）, womersleyi（Schicha）, Amblyseius eharai Amitai and Swirski, Euseius sojaensis（Ehara）（Acari: Phytoseiidae）were collected from commercial Japanese pear orchards in Shizuoka Prefecture. To evaluate the suppressive effect of generalist species on spider Tetranychus kanzawai Kishida（Acari: Tetranychidae）, we compared four treatments（E. sojaensis release, A. synthetic pyrethroid application, no-release）performed a greenhouse. These treatments were conducted when T. densities low, pine pollen was provided as alternative food for predatory mites all treatments. At late June, peak significantly low E. release no-release with application release. The dominant no sojaensis. After July, however, became lower well no-release, thus higher at early August. results suggest that conservation augmentative prior to population increase, might suppress outbreak this until summer.