Inherited Sterility in Codling Moth (Lepidoptera: Tortricidae): Effect of Substerilizing Doses of Radiation on Insect Fecundity, Fertility, and Control

Male and female codling moths, Cydia pomonella (L.), were treated with increasing doses of gamma radiation, and the moths were either inbred or outcrossed with fertile counterparts. Fecundity of untreated females mated with treated males declined slowly with increasing doses of radiation. However, fecundity of treated females declined almost linearly with dose at ≈22% per 100 Gy. The minimum dose at which treated females were found to be 100% sterile when mated to untreated males was 100 Gy. This dose was much lower than previously suggested. Fertility of treated males declined almost linearly to approach 0 near 400 Gy. Inherited effects resulting from irradiation of P1 males at selected doses were recorded for the F1 generation. As the dose of radiation increased, F1 fecundity and fertility decreased, mortality increased, and the F1 sex ratio shifted in favor of male progeny. The effect of releasing partially sterile codling moth males and fully sterile females at a 10:1 overflooding ratio in conjunction with untreated codling moths was examined in field cages each containing a single apple tree. Fruit damage was significantly reduced in all treatments when compared with controls, and production of F1 progeny were seen in cages containing moths treated with 100 Gy.