Gene flow between natural and domestic populations of Lutzomyia longipalpis (Diptera : Psychodidae) in a restricted focus of American visceral leishmaniasis in Venezuela

The epidemiology of the visceral leishmaniasis in the Americas is associate d with both a natural and a domestic cycle. The existence of reproductively isolated populations of Lutzomyia longipalpis (Lutz & Neiva), and the scar city of records of this species from natural habitats in areas where it has been associated with domestic habitats indicated that natural populations could be genetically distinct from domestic ones. Therefore, we compared th e genetic structure and estimated the gene now between L. longipalpis from domestic and peridomestic habitat and from an adjacent undisturbed natural environment along a 1.2-km transect. The analyses were performed on electro phoretic data from eight isozyme loci. The absence of fixed differences in the diagnostic loci Ak and Hk indicated that all specimens belonged to one of the two cryptic species identified in Venezuela. The average number of a lleles per locus ranged from 2.0 to 2.9 and the average heterozygosity rang ed from 7.8 to 13.4%. No differences were detected in the genetic structure of this species from domestic or peridomestic habitats and those trapped a s far as 1.2 km from human dwellings. Nm, estimated from Wright's F-st, ind icated that at least 208 individuals per generation migrated between the pe ridomestic habitat and a 1.2-km distant point to maintain the observed simi larities in allelic frequencies. This high rate of gene now indicated that this species has high migration rates between domestic and natural environm ents, and has the potential to transport for Leishmania from natural to dom estic environments.