Abstract
Yellow tea thrips, Scirtothrips dorsalis, is an important pest of grapevines. With the aim of managing phytoseiid mites as natural enemies of S. dorsalis in vineyards, at two study sites we investigated the occurrence of phytoseiid mites and phytophagous thrips on forage soybean, Glycine max, which is a traditional green manure plant in orchards. In upland fields at Tsukuba in 2004, the phytoseiid mite Gynaeseius liturivorus increased in numbers from August to September and dominated (at over 90%) among the five species of phytoseiid mite collected. In vineyards at Akitsu in 2005 and 2006, of the seven species of phytoseiid mite recorded, G. liturivorus was dominant in August 2005 and Euseius sojaensis and Amblyseius eharai predominated in 2006. Mycterothrips glycines and Hydatothrips abdominalis were the main phytophagous thrips recorded at Tsukuba in 2004 and Akitsu in 2005. H. abdominalis and Thrips setosus were the main thrips recorded at Akitsu in 2006. These are not pests of Japan’s main fruit crops, including grapevines. Scirtothrips dorsalis was not found on forage soybean at either site. In autumn 2006, more phytoseiid mites were captured in grapevine trees undersown with forage soybean than in grapevine trees without soybean. These results suggested that forage soybean in vineyards acted as a reservoir of phytoseiid mites and maintained them at higher density on trellised grapevines.
