Abstract
The control effect of anthocorid predators, Orius spp., against Thrips palmi KARNY on greenhouse eggplant was evaluated by releasing various numbers of predator nymphs and then examining the population fluctuations of the prey and the predators. When two, three and five last instar nymphs of the predators were released per plant, the total density of Orius spp. adults and nymphs reached 0.1, and the T. palmi density decreased to 0.6 per leaf several weeks after the release (regardless of the number of predators released). Both populations fluctuated around that density afterwards. I concluded that Orius spp. could successfully control the population of T. palmi for a long period. In such successful control, the percentage of injured fruits is estimated to be 10%, but it appears that it would be impossible to further lower the T. palmi density by increasing predator density.
