COMPARISON OF THE MITOTIC KARYOTYPES OF CERATITIS-CAPITATA, CERATITIS-ROSA, AND TRIRHITHRUM-COFFEAE (DIPTERA, TEPHRITIDAE) BY C-BANDING ANDFISH

The sex chromosomes of the tephritid fruit fly Ceratitis capitata (Wie demann) are heteromorphic. The male-determining region was located on the Y chromosome by deletion mapping using unbalanced offspring from s everal translocation strains. In addition, we showed that only 15% of the Y chromosome is required for male determination and male fertility . Based on this result, we expected to find Y-chromosomal length polym orphism in natural populations. Using fluorescence in situ hybridizati on with two repetitive DNA probes that label the Y chromosome, no obvi ous size differences were detected in seven wild-type strains and thre e mutant strains. As the medfly is probably of East African origin, we also analyzed two wild-type strains established recently from pupae s ampled in Kenya. The Y chromosomes show a polymorphism in the hybridiz ation pattern of a repetitive Y-specific medfly clone. However, the ov erall size of the Y chromosome is similar to that of the other strains . Besides C. capitata, the tephritid fruit flies Ceratitis (Pterandrus ) rosa Karsch and Trirhithrum coffeae Bezzi also emerged from pupae sa mpled in Kenya. Their karyotype was analyzed by C-banding. Furthermore , the ribosomal genes were mapped to the sex chromosomes in these two species.