Population management of Thrips palmi Karny

Abstract

Heavy damage to vegetables caused by Thrips palmi Karny is widespread in the tropical and sub-tropical regions of the world. The first appearance of this species in Japan occurred in Miyazaki in 1978. It has since become the most serious pest of cucumber, eggplant and sweet pepper in the western part of Japan. The following characteristics as a pest can be identified from its life cycle and population dynamics: preference for young tissues as a host, a high reproductive rate, a wide range of host plants, inability to survive under the very low and the very high temperatures and low sensitivity to insecticides. The effect of various types of chemicals and various kinds of physical control methods were tested against T. palmi, but since the effect of each method is not effective, the integration of several control methods is necessary. From a simulation on the basis of a population model for T. palmi, the following conclusions were derived; 1) because of the severe low density effect, it is recommended that the population be maintained at a very low density level; 2) insect control with insecticides alone is not adequate; 3) control methods based on cultural practices are also effective suppressing the population density. A control system for T. palmi in a greenhouse is discussed.