天敵温存植物で増殖したケナガカブリダニによるチャのカンザワハダニの密度抑制効果

Abstract

We investigated the control of Kanzawa spider mite, Tetranychus kanzawai Kishida on tea by utilizing “natural enemy preservation plants”. The plants were used as hosts for the growth of the predatory mite Neoseiulus womersleyi (Schicha). First, we screened for plants on which N. womersleyi would proliferate, using Tetranychus urticae Koch as the non-pest prey, and identified Tithonia rotundifolia as a candidate natural enemy preservation plant. Next, we tested the effectiveness of T. rotundifolia for supporting a population of N. womersleyi and thus suppressing the population density of T. kanzawai on tea. When T. urticae were released onto T. rotundifolia growing at the edge of a tea field, the population density of N. womersleyi increased and the dispersal of N. womersleyi towards the middle of the tea field was observed. In addition, the density of T. kanzawai in the test plot was lower than in the control plot. These results suggest that N. womersleyi proliferated on natural enemy preservation plants suppressed the population density of T. kanzawai and that T. rotundifolia is effective as a natural enemy preservation plant.