Phylogeographic Pattern of Aedes aegypti from Argentina: Multiple Introductions, Relictual Populations and Long Distance Colonization

ALBRIEU LLINÁS, GUILLERMO

San Juan, Puerto Rico

Congreso; A Re-Emerging Challenge in the Americas: Opportunities for Dengue Research Collaboration; 2011

National Institute of Allergy and Infectious Diseases (NIAID)-National Institute of Health (NIH)-EEUU

Aedes aegypti was originally introduced into the Americas from western Africa between the 15th and 17th centuries; in Argentina, it is at present established in all the central and northern provinces. The analysis of sequences of the mitochondrial gene ND4 allowed us to determine the presence of 3 Ae. aegypti haplotypes in our country, representing lineages previously identified in other countries of America, Africa and Asia. The colonization pattern of Ae. aegypti in different regions of Argentina from neighboring countries was inferred by a phylogeographic study based on the analysis of sequences of the ND5 gene. At a regional scale, high haplotypic and nucleotidic diversities in populations from Northwestern and Northeastern Argentina (NWA and NEA) were observed, contrasting with extremely low levels of polymorphism in several populations from the East, probably because they represent two groups of populations that have experienced different historical processes. The limited genetic exchange between NWA and NEA was also reflected in the genetic discontinuity observed in haplotype networks, well supported by different methods. Past fragmentation and local isolation, followed by the restoration of relictual populations and re-colonization was inferred by means of a Nested Clades Analysis in NWA. It is remarkable the presence of a particular haplotype in NEA in very high frequency and wide geographical distribution; in this region, a recent range expansion in a relatively short period could explain the results obtained. Although population densities may have felt drastically after a massive control campaign, it is possible that a complete eradication had not actually been achieved in some regions of Argentina. On the basis of the analysis of a hypervariable fragment of the mtDNA control region, we also detected a recent range expansion of the species in Argentina. The local effect of passive transportation of Ae. aegypti through the main routes of terrestrial trade from neighboring countries is discussed.