Inherited sterility in different strains of Ephestia cautella (Lepidoptera: Pyralidae)

Abstract

Partial sterility induced by gamma irradiation of Ephestia cauteUa adult males was studied in five laboratory strains (A,B>C,D and E) which exhibit conspicuous genetic variation in the adult forewing pigmentation. Four of these strains had been reared in the laboratory for more than 80 generations, while the fifth strain has been reared for only 10 generations. When males irradiated with 0.2 kGy were crossed with untreated females, the per cent egg hatch was reduced significantly as compared to the unirradiated control crosses. Strain C showed the highest reduction in the per cent egg hatch followed by a gradual decrease in radiation sensitivity in strains A,E,D and B, respectively. Fecundity and mating frequency appeared not to be affected but the sex ratios were clearly distorted (about two males to one female) in all strains. F, progeny of all strains were either sterile when mated together (per cent egg hatch=0.0%), but semi sterile when F ( males were mated to normal females (per cent egg hatch = 0.03-3.95 %). Low fertility was observed when F ( females were mated with normal males (per cent egg hatch = 1.30-15.04%). The cytogenetical investigations showed spermatogenesis to proceed normally in the F t males, whose fathers had been irradiated (0.2 kGy). However, the primary spermatocyte cells carried multiple chromosomal translations which were the main cause of the sterility in the F t males.

Effects of sublethal doses of gamma radiation on the mating ability and spermatophore transfer of Ephestia cautella (Lepidoptera: Pyralidae)

“…The methods of rearing and irradiation used are identical to those described elsewhere (Ahmed et al, 1975;Al-Taweel et al, 1989). The experiments were carried out on three age groups: In group 1,5-6 days old male pupae were notradiated, and after emergence the adults were divided into three subgroups of 24,48 and 72 hr, which were mated singly or in groups of five males with unirradiated 24-hr old virgin females.…”