METAPHASE KARYOTYPES OF FRUIT FLIES OF THAILAND II. FIVE SPECIES IN FOUR SUBGENERA OF BACTROCERA

Abstract

Five species of fruit flies of the genus Bactrocera (Diptera, Tephritidae) collected from natural populations at different localities in Thailand were examined cytologically. They showed distinctive metaphase karyotypes with respect to the amount and distribution of constitutive heterochromatin in centromeric regions of autosomes and sex chromosomes. Bactrocera (Hemigymnodacus) diversa, B. (Bactrocera) latifrons and B. (Asiadacus) modica, three distinct species belonging to different subgenera, clearly exhibited different pericentric heterochromatin in all autosome pairs. The large metacentric X chromosome and conspicuous blocks of heterochromatin of B. (B.) latifrons makes it distinctive from B. (A.) modica and B. (H.) diversa. Further, B. (Z.) rubella and B. (Z.) scutellaris belong to the same subgenus Zeugodacus, but they have different metaphase karyotypes based on the amount of centromeric heterochromatin in all autosomes. The X and Y chromosomes of B. scutellaris are much longer than those of Z. rubella due to accumulation of large quantities of heterochromatin. Such cytological differences among these distinct species are very useful as diagnostic characters in cytotaxonomic studies and may provide information concerning chromosomal evolution of these important pests in Thailand.