Influence of Radiation-Induced Genetic Damage on the Suppressive Effect of Inherited Sterility in the Codling Moth (Lepidoptera: Tortricidae)

The phenomenon of inherited sterility and its connection with radiation-induced chromosome aberrations has been known since 1935. In this study, the genetic basis for inherited sterility and its manifestation in the codling moth, Laspeyresia pomonella (L.), is examined after doses of radiation from 3 to 30 krad. Two types of sterility were observed: fully sterile pairs of moths that either did not oviposit eggs or by which eggs were laid but with no signs of embryonic development; partially sterile pairs that laid eggs in which some of the embryos developed normally and others died during development. These two types of sterility have different genetic bases. The fully sterile pairs were further divided into two groups: coupling and noncoupling. The frequency of noncoupling F1 males increased at high doses of radiation, reaching 90% at 30 krad. At this dose, competitiveness of F1 males was 4% of untreated males. A large percentage of eggs laid by treated females died during development, and the frequency of such deaths increased with increasing doses of radiation. The 10-krad dose appeared to be advantageous for use in an inherited sterility program from the standpoint of postzygotic mortality and competitiveness but did not provide full sterilization of females.