Genetic structure of natural populations of the sand fly Lutzomyia longipalpis (Diptera: Psychodidae) from the Brazilian northeastern region.

In Latin America, Lutzomyia longipalpis is the principal vector of Leishmania chagasi, and is associated with the majority of active foci of visceral leishmaniasis. In spite of the fact that this sand fly is spread practically throughout the entire Neotropical Region, its distribution is not uniform due to geographic and environmental barriers. Geographic isolation coupled with reduced flight abilities may contribute to the appearance of cryptic species of Lutzomyia longipalpis, which may differ in their capacity to transmit L. chagasi. In this work, we describe the genetic structuring patterns based on polymorphism analysis of 24 RAPD-PCR loci of 7 natural populations of Lutzomyia longipalpis obtained from Brazil's northeastern region. The estimated degree of genetic differentiation between populations, based on the population subdivision index theta(ST) (0.136), suggests a moderate degree of genetic structuring as a result of geographical isolation and restricted gene flow. Genetic distances were found to be compatible with those found between members of a single species, suggesting a taxonomic uniformity of Lutzomyia longipalpis in the region studied.