About 30 yr after malaria eradication, surveys to assess the presence and abundance of anopheline vectors were carried out in central and southern Italy and in the islands of Sardinia and Sicily from 1992 to 1994. Anopheles labranchiae Falleroni was present in scattered foci in all regions, except for Tuscany, where it breeds almost exclusively in rice fields (Grosseto Province). Most common breeding sites were rivers and streams, followed by ponds and ground pools. The highest adult density was found in Tuscany near rice fields and along the west coast of Calabria. Anophelines in Grosseto were abundant at human bait, with peaks of > 200 landings per human per night and vectorial capacity between 7.3 and 26 for Plasmodium falciparum and between 8.3 and 32.5 for Plasmodium vivax. Anopheles sacharovi Favre, a former malaria vector in Puglia and Sardinia, was not found in these regions. The other vector in southern Italy, Anopheles superpictus Grassi, was found at low densities on the western and eastern coasts of Calabria. All anopheline populations were fully susceptible to deltamethrin, malathion, and DDT but showed reduced susceptibility to permethrin and propoxur. These data are discussed in the light of a possible reintroduction of malaria into Italy.

Fluorescence in situ hybridization (FISH) was used to localize the 18S-28S ribosomal RNA gene clusters on the chromosomes of 15 mosquito species belonging to the Anophelinae and Culicinae subfamilies. In the genus Anopheles the rRNA genes are localized on the heterochromatic arm of both sex chromosomes. The association between rRNA genes and sex determining chromosomes also applies to the homomorphic karyotype of Culicinae mosquitoes, at least in those cases in which localization of the sex locus/loci has been determined. In these species ribosomal genes are often found within or adjacent to heterochromatic regions (C bands). Differences in the location of rRNA genes among and within genera suggest the occurrence of several chromosomal rearrangements during the evolution of mosquitoes.

Electrophoretic analysis of 17 enzyme loci was carried out to assess the genetic differentiation and isolation of the Sardinian Polyommatus coridon gennargenti from R c. apennina of peninsular Italy and the related taxon P caelestissimus from central Spain. I? c. gennargenti is represented by a small, strongly inbred population, restricted to the central mountains of Sardinia, and probably derived from mainland populations as indicated by the reduction of genetic variation (P 17.6 per cent, H 0.024) with respect to the continental populations (P>52 per cent, H 0.170). Absence of gene flow is indicated by the presence of alternative fixed alleles at the Aat, Gpi and Pgm loci and significant differences in allele frequencies at other loci, which distinguish the Sardinian population from 1? C. apennina and P caelestissimus. The genetic differentiation of P c. gennargenti, as measured using Wright's FST values and Nei's genetic distances, suggests the evolution of the Sardinian taxon along an independent lineage, facilitated by isolation and the strict dependence of the butterflies on specific biotopes, thus confirming its taxonomic status.

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