Mechanisms of Reproductive Isolation between the Fruit-Feeding and the Pinaceae-Feeding Types of the Yellow Peach Moth, Dichocrocis punctiferalis Guenee (Lepidoptera: Pyralidae)

Two types of the yellow peach moth, Dichocrocis punctiferalis Guen éE, Namely the polyphagous fruit-feeder attacking the fruits of 30 species in 15 families of Angiospermae, and the other as the oligophagous Pinaceae-feeder attacking only young leaves of Pinus and Cedrus of Pinaceae have been known to occur in Japan. In the present study, the mechanism of reproductive isolation between these two types was investigated in the laboratory. Although the mating behavior and calling posture of these types were almost similar, the calling frequency of the Pinaceaefeeder was remarkably lower than that of the fruit-feeder. The mating time was slightly different between the two types, when these were caged separately under artificial conditions (15L9D), i.e., the peak of mating-time of Pinaceae-feeder was found to occur 1.5 hr earlier than that of the fruit-feeder. Besides, these activities were significantly delayed in the presence of both sexes of the other type. The females of both types attracted not only the males of the same type, but also the males of different type in the laboratory attraction tests. This result suggests that the female sex-pheromones have a common component(s) enabling to attract the males of both types. However, in the mating-choice tests, in which males and females of both types were caged together, all matings occurred within the same type. Therefore, the mechanism underlaying sexual isolation must be different in the two types.