Cage evaluation of augmentative biological control of Thrips palmi with Wollastoniella rotunda in winter greenhouses

Cage trials of an anthocorid predator, Wollastoniella rotunda Yasunaga et Miyamoto, as a biological control agent of Thrips palmi Karny were conducted in Fukuoka, Japan, under winter greenhouse production conditions. Females of W. rotunda were released on caged eggplants, and placed in two greenhouses on 27 October. The development, population growth, and effectiveness of W. rotunda were observed until early March. Results from the cage trials showed that W. rotunda successfully developed, reproduced, and suppressed T. palmi populations under the conditions found in winter greenhouses. During the experiment, one full generation and a second generation of adult predators occurred. The T. palmi population which was exposed to predators remained at a low density throughout the trial period, but it increased dramatically on eggplants without W. rotunda. The maximum difference between predator treatments and controls was approximately 10‐fold by the end of January. Wollastoniella rotunda has the potential to be an effective control agent for T. palmi on eggplant, even during the winter in temperate regions.