Abstract
Phyllonorycter sorbicola is known as an apple pest in Shikoku, Japan. Overwintering pupae were collected from apple orchards in the following localities: Shodoshima (Kagawa Pref.), Takamatsu (Kagawa Pref.) and Kamiita (Tokushima Pref.). These three populations were reared on young apple trees in Morioka. By applying the mass mating method, it was found that the Takamatsu population produced 66 to 84% of females, and the percentage of females increased steadily in the subsequent generations, whereas both Shodoshima and Kamiita populations produced about 50% of females regardless of the generation. On the other hand, the use of the single female mating method enabled to demonstrate that out of the nine females of the Takamatsu population that mated with males of the same population, eight yielded normal progenies, but one produced 13 females with no male. Furthermore, when nine females from this unisexual brood were crossed to males of the Kamiita population in using the single female mating method, six females yielded unisexual progenies and three yielded normal progenies. In contrast, when females obtained from a bisexual brood were crossed to males of the same or different brood, they produced normal bisexual progenies. In these experiments, it was also indicated that the abnormal females oviposited nearly the same number of eggs as the normal ones.
