Comparative Performance of Two Predatory Mites in Managing Western Flower Thrips in Protected Rose Flower Farms in Central Ethiopia

Abstract

The application of pesticides has been causing economic, health and environmental impact in the rose flower industry. To mitigate this, introduction of biological control agents was promoted and was successful in reducing spider mites, which used to require application of pesticides every three days in the worst case scenarios. But when this major pest of roses was effectively controlled using the introduced bio control agents, secondary pest outbreak became common. This included citrus mealybug, western flower thrips (WFT), aphids and bollworms. The WFT is a quarantine pest in most of the importing countries. Therefore biological control agents should have been evaluated on WFT. To this effect, two predatory mites (Amblyseus cucumeries and A. swiriskii) were compared. The two predators were released in separate greenhouses alone or in combination with either compatible pesticides or yellow sticky traps. It was found that A. cucumeries effectively controlled WFT than the other predatory species. The use of compatible
pesticide reduced the pest population near to zero. Beside this the hanging of sticky traps in big number also reduced the pest population significantly. There was also farm-wide verification of A. cucumeries, in which significant reduction of WFT was recorded over the sampling period. Therefore the use of A. cucumeries and the yellow sticky traps could be promoted with application of soft or compatible pesticides to effectively control the WFT.