カメムシ類雄成虫のフェロモンとそれによる天敵捕食寄生者の誘引

Abstract

It has been reported that male adults attract conspecific individuals in some species of true bugs (Heteroptera). Chemical stimuli play an important role in these attractions. Male adults attract adults of both sexes and nymphs, so the chemical stimuli are considered as “aggregation pheromones.” Some aggregation pheromones in these bugs have been identified and synthesized, but their functions have not been fully determined. It is necessary to clarify the functional significance of aggregation pheromones in order to utilize them for the control of pest bugs. The aggregation pheromones of some bug species also attract the bug's natural enemies, parasitic flies, egg parasitoids, and so on. Female parasitoids utilize the host pheromone as a kairomone to locate their hosts. Males of the bean bug Riptortus clavatus, an economically important soybean pest, emit an aggregation pheromone that attracts adults of both sexes and nymphs. The aggregation pheromone of R. clavatus consists of three components: (E)-2-hexenyl (E)-2-hexenoate, (E)-2-hexenyl (Z)-3-hexenoate (E2HZ3H), and tetradecyl isobutyrate. One of the three components alone, E2HZ3H, attracted females of the egg parasitoid Ooencyrtus nezarae, which is a predominant natural enemy of R. clavatus. E2HZ3H, however, did not attract R. clavatus. In an E2HZ3H-treated field, the parasitoids immigrated into the field earlier than the invasion of R. clavatus, and remained at higher densities than in an untreated field. E2HZ3H did not increase the density of the pest host bug. According to the data obtained from the eggs of the bugs artificially set on soybean plants, the E2HZ3H field application resulted in higher parasitism by the parasitoids as compared with the untreated field when the parasitoid density was high in autumn.