Radiation-Induced Inherited Sterility Combined with a Genetic Sexing System in Ephestia kuehniella (Lepidoptera: Pyralidae)

The Mediterranean flour moth, Ephestia kuehniella Zeller, is the only lepidopteran pest in which a genetic sexing technique is available. We investigated the potential of using genetic sexing to enhance the effectiveness of F1 sterility in population suppression. The irradiation dose–response relationship in the parental (P) generation of the moth was determined and related to the level of inherited sterility expressed in the F1 generation. One generation before irradiation, males of the BL-2 strain, which are trans-heterozygous for 2 sex-linked recessive lethal mutations (sl-2 and sl-15), were mated to females of the wild-type strain WT-C. Progeny of these matings consisted exclusively of males (sl/+). All female progeny died because they were hemizygous for either sl-2 or sl-15. The sl/+ males were treated with 8 doses of gamma rays ranging from 100 to 350 Gy and mated to WT-C females. The resulting data on the P and F1 generations revealed that E. kuehniella is extremely radioresistant. Irradiation at all doses had little influence on the mating success of sl/+ males and on fecundity of parental pairs. At lower doses, most embryonic mortality originated from the expression of lethal alleles sl-2 and sl-15. The egg hatch significantly decreased starting at 150 Gy, but effects of irradiation became evident only at doses higher than 200 Gy. In reciprocal F1 matings, the level of induced inherited sterility correlated positively with the irradiation dose. F1 males exhibited a higher level of induced sterility than F1 females; it indicates that induced mutations have a sex-dependent impact. Optimal doses for the induction of F1 sterility in E. kuehniella with the use of genetic sexing are in the range of 175–200 Gy.