Population trends of Orius sauteri (Poppius) (Heteroptera: Anthodoridae) on weeds in spring

To learn the habitat of Orius sauteri (Poppius) in spring, eight species of weeds were investigated for the occurrence of O. sauteri in relation to the abundance of prey (thrips, aphids, and spider mites) from mid March to late May in Kagoshima Prefecture. Population trends of O. sauteri was synchronized with the abundance of thrips, but not with that of aphids and spider mites. Actually, a significant correlation was found between the density of O. sauteri and thrips. In April, O. sauteri, mostly in the nymphal stage, were found only on Artemisia princeps Pampan. It contrast, after May, O. sauteri appeared on various plants such as Geranium carolinianum L., Vicia angustifolia L., and Galium spurium L., with the increase of thrips on these plants. Adults of O. sauteri found from April to early May were all females; O. sauteri males appeared after mid May. These results suggested that the habitat of O. sauteri is dependent on thrips populations, and that the first generation adults of O. sauteri occurred after mid May.