Effect of covering with red insect screen to control Thrips tabaci (Thysanoptera: Thripidae) on cabbage

Physical control using insect screens is expected as an alternative method to chemical control. However, insect screens with finer mesh sizes to exclude minute pests have the problem of achieving both a control effect and ventilation. We evaluated the suppressive effect of a red insect screen on a Thrips tabaci Lindeman (Thysanoptera: Thripidae) population on cabbage in 2011. The number of T. tabaci on cabbage covered with a red insect screen was significantly lower than that with a white insect screen with the same mesh size. Further investigations in 2017 and 2018 revealed that the control effect of the red insect screen was not different between 0.6- and 0.8-mm mesh sizes, and better than that of the white insect screen with a 0.4-mm mesh size. According to catching test with sticky traps, camouflage for cabbage by red insect screen is considered as possible mechanisms for the control effect. These characteristics should make it possible to achieve both ventilation and an effect to control T. tabaci on cabbage. Furthermore, early growth of cabbage seedlings was not different between covering red and white insect screen with 0.8-mm mesh size. From these results, we discuss the beneficial effects of red insect screens.