Meiotic disjunction and embryonic lethality in sex-linked double-translocation heterozygous males of the onion fly, Hylemya antiqua (Meigen).

The frequencies of disjunction types in double-translocation heterozygous males (2(6)2(Y)6(2)6XY(2)) in Hylemya antiqua have been established in MII cells and eggs of testcrosses.Several disjunction types occurred but four predominated. A correlation was found between the frequencies of the disjunction types and the relative position of the centromeres. The frequency of numerical non-disjunction (NND) was 4%. Differences in frequency of NND between sex-linked and autosomal translocations of H. antiqua are discussed. A good correspondence between the frequencies of unbalanced karyotypes, and embryonic and larval mortality was found. The total genetic load which can be induced by the T14/T61 males is estimated to be 60-65%. Some duplication/deficiency karyotypes appeared to be viable in pupal and even adult stages. In 2(6)2(6)2(Y)6(2)6(2)X males a regular coorientation between 2(Y) and X was observed, in spite of non-homologous centromeres and a complicated synapsis of 2(Y). Application possibilities of the present material for genetic control of H. antiqua are discussed.