Natural Enemies of Thrips palmi and Their Effectiveness in the Native Habitat, Thailand

A survey for natural enemies of Thrips palmi Karny was conducted in its native habitat, Thailand, in 1987 and 1988 to develop a classical biological control program for this exotic pest of vegetables in Japan. One egg parasitoid, one larval parasitoid, and six larval predators were found. Of these eight natural enemies, the eulophid larval parasitoid Ceranisus menes (Walker) was the most effective, based on a study in a test plot of eggplant in Bangkok and an extensive survey of eggplant fields in several districts of Thailand in 1988. Parasitism by C. menes was usually limited to home gardens which were not sprayed with insecticides, suggesting a detrimental effect of insecticide applications on the parasitoid. The anthocorid larval predator Bilia sp. was the second most effective natural enemy. Problems associated with the introduction of these two promising biological control agents in relation to the occurrence of native natural enemies of T. palmi in Japan are discussed.