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

Dendrothrips minowai Priesner (Thysanoptera: Thripidae) is the main pest thrips in tea (Camellia sinensis) plantations in Guizhou Province, damaging tea shoots and leaves. In this study, we tested the control of the predatory mite Amblyseius cucumeris Oudermans and the ladybeetle Harmonia axyridis Pallas against D. minowai in the laboratory and tea plantations in Guizhou, China. The results showed that D. minowai suppression by A. cucumeris was 29.0% at the predator to prey ratio of 1:10 and 45.3% at 1:5, and by H. axyridis 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 D. minowai (between May and August), the release of A. cucumeris and H. axyridis reduced D. minowai by 26.3 and 56.7% in 2015 and by 40.3 and 54.5% in 2016, respectively. Densities of A. cucumeris and H. axyridis 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, A. cucumeris and H. axyridis can be used as effective predators in controlling D. minowai in Chinese tea plantations.