Heterochromatin Distribution in Mitotic Metaphase Karyotypes of the Peach Fruit Fly, Bactrocera zonata and the Pumpkin Fruit Fly, Zeugodacus tau (Diptera, Tephritidae), with C-Banding Technique

Mitotic metaphase karyotypes of the two economically important fruit fly species, Bactrocera zonata and Zeugodacus tau, with C-banding technique were studied to understand their genomic organization and distribution patterns. Both species consist of a diploid set with 12 biarmed (2n = 12) chromosomes including one pair of heteromorphic (XX/XY) sex chromosomes. We found a characteristic distribution pattern in both species with positive C+ bands in all chromosome sets in their centromere region. Chromosome 2 in both species consisted of minimal amount of heterochromatin while two C+ bands decorated the X chromosome of male Z. tau in their centromeric and telomeric region and X chromosome in female had no C-band in their telomeric region in short arm. Long arms of the X chromosome in both sexes were totally heterochromatic. In both species, the Y chromosome is dot-shaped with almost fully heterochromatic and deeply stained. Moreover, metacentric X chromosomes in both sexes of B. zonata contained one thin telomeric C+ band in their short arm with one deep band in the centromeric region. The present findings revealed the knowledge of genomic structure as well as contribute to the understanding of interference of heterochromatin in ontogeny and chromosomal evolution of these two fruit fly species.