Posttreatment development and fertility of nondiapausing codling moth (Lepidoptera: Tortricidae) larvae and their progeny following gamma irradiation

Nondiapausing coding moth, Cydia pomonella (L.), larvae were exposed to gamma irradiation at a rate of 14.3-15.7 Gray (Gy)/min. Based on percentages of larvae that developed to pupae, adults, and physically normal adults, sensitivity to radiation increased with increasing dose and decreasing age, and females were more sensitive than males. The effect of radiation on insects is often delayed in that it occurs in developmental stages subsequent to that on which the treatment is applied. A study to determine the minimum dose required to produce detrimental effects on subsequent developmental stages showed that LD(99)s (95% upper confidence limit) were 233 (284) Gy to prevent pupation and 126 (147) Gy to prevent adult emergence. At 60 Gy, only infertile males developed to physically normal adults from treated larvae. Thus, an irradiation treatment that prevents surviving individuals from mating and producing fertile progeny still serves the purpose of preventing establishment of a quarantine pest. Adults of both sexes from larvae treated at 40 Gy were fertile, and single-pair reciprocal crosses of their adult progeny with untreated moths showed no evidence of delayed or F-1 sterility.