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 composed of 12 chromosomes. The haploid karyotype is composed of 4 submetacentric and 1 metacentric autosomes, a dot-like Y chromosome and a submetacentric 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 chromosomes. 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 Hardy 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 band on the long arm of the second pair, the short arm entirely banded and a large subcentromeric band on the X chromosome. The Y chromosome was completely banded.