Difference in Response of Riptortus clavatus (Thunberg) (Heteroptera: Alydidae) and Its Egg Parasitoid Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) to the Synthetic Aggregation Pheromone of R. clavatus

Abstract

We investigated the attractiveness of the synthetic male aggregation pheromone of Riptortus clavatus for conspecific adults and its parasitic wasp, Ooencyrtus nezarae, using traps placed in fields. The number of R. clavatus adults caught in the pheromone traps increased with increasing amounts of the pheromone lure up to 100mg. This amount of the synthetic aggregation pheromone seemed to have attractiveness equivalent to ten caged R. clavatus males in summer. However the pheromone traps caught many more adult bugs than the male trap in autumn, suggesting that the amounts of pheromone released from the male bugs change greatly depending on the temperature. Five miligram of (E)-2-hexenyl(Z)-3-hexenoate (E2HZ3H), a component of the synthetic aggregation pheromone, showed the highest attractiveness to O. nezarae. Ten to 50 mg of the synthetic aggregation pheromone which contained 1.4 to 7mg of E2HZ3H exhibited a peak in O. nezarae catches. Thus, the attractiveness of the synthetic aggregation pheromone to O. nezarae may be simply attributed to the presence of E2HZ3H in the pheromone.