HYBRID DYSGENESIS-LIKE PHENOMENA IN THE MEDFLY, CERATITIS-CAPITATA (DIPTERA, TEPHRITIDAE)

A syndrome of abnormal genetic effects, which resembles Drosophila hyb rid dysgenesis, is described in Ceratitis capitata. This syndrome incl udes high frequency of partial or complete female gonadal sterility, c hromosomal rearrangements (bridges and fragments) at male meiosis, and instabilities at the white eye locus. It was observed in hybrids of C . capitata when strains of different origin were mated. The morphology of the undeveloped ovaries recovered in the medfly is apparently very similar to the gonadal distrophy which in D. melanogaster is associat ed with the P-M and hobo mediated dysgenic syndromes. The amount of go nadal sterility that can be observed in medfly hybrids depends on the parental strains used, which exhibit specific differences in their ind ucing abilities. In the considered interstrain combinations, there app ears to be quantitative variation in the effect of temperature on GD s terility. The highest level of sterility occurs at 25 degrees C. The p attern of abnormal traits observed in medfly hybrids appears to be the phenotypic expression of a rather complex interacting dysgenic system of inducer and suppressor effects; probably more than one system is a ctivated in the considered crosses.