Population management of Thrips palmi Karny.

Heavy damage to vegetables caused by Thrips palmi Karny is widespread in th e tropical and sub-tropical regions of the world. The first appearance of t his 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 par t of japan. The following characteristics as a pest can be identified from its life cycle and population dynamics: preference for young tissues as a h ost, a high reproductive rate. a wide range of host plants, inability to su rvive under the very low and the very high temperatures and low sensitivity to insecticides. The effect of various types of chemicals and various kind s of physical control methods were tested against T. palmi, but since the e ffect of each method is not effective, the integration of several control m ethods is necessary. From a simulation on the basis of a population model f or T. palmi, the following conclusions were derived: 1) because of the seve re low density effect, it is recommended that the population be maintained at a very low density level; 2) insect control with insecticides alone is n ot adequate: 3) control methods based on cultural practices are also effect ive suppressing the population density. A control system for T. palmi in a greenhouse is discussed.