KARYOLOGY OF SOME ITALIAN POPULATIONS OF THE OLIVE FLY BACTROCERA-OLEAE (GMELIN) (DIPTERA, TEPHRITIDAE)

A karyometric analysis of the olive fly, Bactrocera oleae, was carried out. Results obtained showed that the diploid set of B. oleae is comp osed of 12 chromosomes. The haploid karyotype is composed of 4 submeta centric and 1 metacentric autosomes, a dot-like Y chromosome and a sub metacentric or metacentric X chromosome. A polymorphism is present on the X chromosome and it is due to a satellite on the short arm of the chromosome. A secondary constriction is present on the third pair of c hromosomes. Study of specimens collected from different localities in Central Italy, Sardinia and Southern Italy showed that as concerns the satellite polymorphism, only females from Southern Italy are not in H ardy Weinberg balance. This female population seems to have an excess of homozygous specimens (with or without satellite) while there appear to be fewer heterozygous specimens than expected. C-banding revealed centromeric bands on the five pairs of autosomes, a subcentromeric ban d on the long arm of the second pair, the short arm entirely banded an d a large subcentromeric band on the X chromosome. The Y chromosome wa s completely banded.