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

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Abstract
The frequencies of disjunction types in double-translocation heterozygous males (262Y626XY2) 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 26262Y6262X males a regular coorientation between 2Y and X was observed, in spite of non-homologous centromeres and a complicated synapsis of 2Y. Application possibilities of the present material for genetic control of H. antiqua are discussed.