Radiation induced semi-sterility for genetic control purposes in the onion fly Hylemya antiqua (Meigen) : II. Induction, isolation and cytogenetic analysis of new chromosomal rearrangements.

The study of the radiobiological and cytogenetic aspects of induced semi-sterility for application in the genetic control of the onion fly Hylemya antiqua (Meigen) has been continued. Doses of 1.5 krad of X-rays or 0.25 krad of fast neutrons were applied to males and 1.0 krad of X-rays or 0.25 krad of fast neutrons to seven day-old females. On the basis of semi-sterility (between 60% and 30% egg hatch) in backcrosses to normal flies, eleven strains were suspected of carrying a chromosomal rearrangement. Seven had a reciprocal translocation and two from a 1.5 krad X-ray treatment showed complex rearrangements. In two strains no rearrangements were found. Two homozygous translocations are described. Combining data of earlier experiments with the new results we concluded that the irradiation of males with low doses, 0.5 krad of X-rays or 0.25 krad of fast neutrons, is suitable for the induction of chromosomal rearrangements. Strains carrying rearrangements from such low dose treatments will be further used for genetic control experiments on the onion fly.