Introduction of two predators to control <i>Dendrothrips minowai</i> (Thysanoptera: Thripidae) in tea (<i>Camellia sinensis)</i> plantations in China

<i>Dendrothrips minowai</i> Priesner (Thysanoptera: Thripidae) is the main pest thrips in tea (<i>Camellia sinensis</i>) plantations in Guizhou Province, damaging tea shoots and leaves. In this study, we tested the control of the predatory mite <i>Amblyseius cucumeris</i> Oudermans and the ladybeetle <i>Harmonia axyridis</i> Pallas against <i>D. minowai</i> in the laboratory and tea plantations in Guizhou, China. The results showed that <i>D. minowai</i> suppression by <i>A. cucumeris</i> was 29.0% at the predator to prey ratio of 1:10 and 45.3% at 1:5, and by <i>H. axyridis</i> it was 45.0% at the 1:10 ratio and 67.2% at 1:5 in the laboratory. After the introduction of these two predators in tea plantations, during the period of highest density of <i>D. minowai</i> (between May and August), the release of <i>A. cucumeris</i> and <i>H. axyridis</i> reduced <i>D. minowai</i> by 26.3 and 56.7% in 2015 and by 40.3 and 54.5% in 2016, respectively. Densities of <i>A. cucumeris</i> and <i>H. axyridis</i> per 100 tea leaves ranged from 50.3 to 137.5 for the mite and from 18.0 to 65.0 for the ladybird beetle. Thus, <i>A. cucumeris</i> and <i>H. axyridis</i> can be used as effective predators in controlling <i>D. minowai</i> in Chinese tea plantations.