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

Abstract

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 F 1 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 F 1 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 F 1 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 F 1 matings. the level of induced inherited sterility correlated positively with the irradiation dose. F 1 males exhibited a higher level of induced sterility than F 1 females; it indicates that induced mutations have a sex-dependent impact. Optimal doses for the induction of F 1 sterility in E. kuehniella with the use of genetic sexing are in the range of 175-200 Gy.