Abstract
Background Lutzomyia longipalpis (Diptera: Psychodidae) is the major vector of Leishmania (Leishmania) infantum and thus plays a crucial role in the epidemiology of American visceral leishmaniasis (AVL). This vector is the best studied species of sand fly in the Neotropical region. Many studies claim that this vector is in fact a species complex; however there is still no consensus regarding the number of species that belong into this complex or the geographical distribution of sibling species. The aim of the present study was to analyze the genetic relationships within Lu. longipalpis populations in the state of Mato Grosso do Sul (MS), Brazil.Methodology/Principal FindingsWe collected 30 Lu. longipalpis (15 females and 15 males) from five localities (Campo Grande, Três Lagoas, Aquidauana, Miranda and Bonito) and 30 Lu. Cruzi from Corumbá, totaling 180 sandflies from MS, and 30 Lu. longipalpis from Estrela de Alagoas, state of Alagoas (AL), Northeast Brazil. We show that eight previously described microsatellite loci were sufficient in distinguishing Lu. longipalpis from Lu. Cruzi, which is a closely related species, and in differentiating between Lu. longipalpis collected in MS versus Estrela de Alagoas. Analyses of the genotypes revealed introgression between sympatric Lu. longipalpis and Lu. Cruzi. Conclusions/SignificanceOur findings support the hypothesis of cryptic species within the Lu. longipalpis complex. Furthermore, our data revealed introgression between Lu. longipalpis and Lu. cruzi. This phenomenon should be further investigated to determine the level and incidence of hybridization between these two species. We also demonstrated that microsatellite markers are a powerful tool for differentiating sand fly populations and species. The present study has elucidated the population structure of Lu. longipalpis in MS and, by extension, the Neotropical Lu. longipalpis complex itself.
Highlights
Leishmaniases are diseases caused by various species of protozoa of the order Kinetoplastida, family Trypanosomatidae and genus Leishmania that affect humans and various wild and domestic animals throughout the world
The phenetic UPGMA tree based on all pairwise Fst estimates illustrated the differences between the two different vectors in Mato Grosso do Sul (MS) (Lu. longipalpis grouped on the upper part of the tree but still separated from Lu. cruzi) and between those MS sandflies and the outgroup (Estrela de Alagoas – AL) at the base of the tree (Figure 2)
We conclude that Lu. longipalpis from MS and AL are diverging populations, consistent with the geographic distance of at least 2.300 Km between these populations compared with the distance observed for all MS populations (654 Km between Três Lagoas and Corumbá Figure 1)
Summary
Leishmaniases are diseases caused by various species of protozoa of the order Kinetoplastida, family Trypanosomatidae and genus Leishmania that affect humans and various wild and domestic animals throughout the world. American visceral Leishmaniasis (AVL) is widely distributed in the state of Mato Grosso do Sul (MS), where it has been reported in several counties [7]. Lutzomyia longipalpis (Diptera: Psychodidae) is the major vector of Leishmania (Leishmania) infantum and plays a crucial role in the epidemiology of American visceral leishmaniasis (AVL). This vector is the best studied species of sand fly in the Neotropical region. The aim of the present study was to analyze the genetic relationships within Lu. longipalpis populations in the state of Mato Grosso do Sul (MS), Brazil. The present study has elucidated the population structure of Lu. longipalpis in MS and, by extension, the Neotropical Lu. longipalpis complex itself
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