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.

茶蓟马（Dendrothrips minowai Priesner）隶属于缨翅目（Thysanoptera）蓟马科（Thripidae），是贵州省茶树（Camellia sinensis）种植园中的主要蓟马类害虫，可蛀食茶梢与叶片造成危害。
本研究在实验室及中国贵州省茶园内，开展了捕食螨胡瓜钝绥螨（Amblyseius cucumeris Oudermans）与异色瓢虫（Harmonia axyridis Pallas）对该蓟马的控害效果测试。
研究结果显示：实验室条件下，当胡瓜钝绥螨与茶蓟马的释放比例为1:10时，其控害率为29.0%；比例为1:5时，控害率达45.3%。而异色瓢虫在1:10的释放比例下控害率为45.0%，1:5比例下控害率可达67.2%。
在茶园释放这两种捕食性天敌后，于茶蓟马种群密度峰值期（5月至8月）进行调查：2015年释放胡瓜钝绥螨与异色瓢虫分别使茶蓟马种群下降26.3%与56.7%；2016年则分别下降40.3%与54.5%。每100片茶叶上，胡瓜钝绥螨的种群密度介于50.3至137.5头，异色瓢虫的种群密度介于18.0至65.0头。
综上，胡瓜钝绥螨与异色瓢虫可作为有效天敌，应用于中国茶园内茶蓟马的生物防治工作。