Regional differences in the density of phytoseiid mites and yellow tea thrips Scirtothrips dorsalis Hood on the windbreaks of bigleaf podocarp trees surrounding citrus orchards

Abstract

In 2007, I determined the densities of phytoseiid mites and yellow tea thrips Scirtothrips dorsalis Hood on the windbreaks of bigleaf podocarp trees Podocarpus macrophyllus that surround citrus orchards in Nishiura and Mikkabi region in Shizuoka prefecture. In the Nishiura region, phytoseiid mites such as Amblyseius eharai, Euseius sojaensis, and Neoseiulus californicus were observed on the windbreaks throughout early May to late July. In the Mikkabi region, phytoseiid mites were not detected on the windbreaks in May, but the density of phytoseiid mites increased slowly on the windbreaks from early June to early July. The total number of phytoseiid mites observed between early May and late July on the windbreaks in the Nishiura region was greater than that in the Mikkabi region. And consequently, the number of S. dorsalis larvae and adults observed on the windbreaks between early June and late July in the Nishiura region was smaller than that in the Mikkabi region. These results suggest that phytoseiid mites can lower the density of S. dorsalis on windbreaks of bigleaf podocarp trees.