Lutzomyia longipalpis is the main vector of Leishmania infantum chagasi, the causative agent of American visceral leishmaniasis (AVL). Although there is strong evidence that Lu. longipalpis is a species complex, not all data concerning populations from Brazil support this hypothesis. The issue is still somewhat controversial for this large part of Lu. longipalpis distribution range even though that it is the Latin American region contributing to most of the cases of AVL. In this mini-review we consider in detail the current data for the Brazilian populations and conclude that Lu. longipalpis is a complex of incipient vector species with a complexity similar to Anopheles gambiae s.s. in Africa.

Lutzomyia longipalpis is the primary vector of American visceral leishmaniasis. There is strong evidence that L. longipalpis is a species complex, but until recently the existence of sibling species among Brazilian populations was considered a controversial issue. In addition, there is still no consensus regarding the number of species occurring in this complex. Using period, a gene that controls circadian rhythms and affects interpulse interval periodicity of the male courtship songs in Drosophila melanogaster and close relatives, we analyzed the molecular polymorphism in a number of L. longipalpis samples from different regions in Brazil and compared the results with our previously published data using the same marker. We also studied the male copulation songs and pheromones from some of these populations. The results obtained so far suggest the existence of two main groups of populations in Brazil, one group representing a single species with males producing Burst-type copulation songs and cembrene-1 pheromones; and a second group that is more heterogeneous and probably represents a number of incipient species producing different combinations of Pulse-type songs and pheromones. Our results reveal a high level of complexity in the divergence and gene-flow among Brazilian populations of the L. longipalpis species complex. This raises important questions concerning the epidemiological consequences of this incipient speciation process. Lutzomyia longipalpis is the main vector of visceral leishmaniasis in the Americas. There is strong evidence that L. longipalpis is a species complex, but there is still no consensus regarding the number of species occurring in Brazil. We combined molecular and behavioral analyses of a number of L. longipalpis populations in order to help clarify this question. This approach has allowed us to identify two main groups of populations in Brazil. One group probably represents a single species distributed mainly throughout the coastal regions of North and Northeast Brazil and whose males produce the same type of copulation song and pheromone. The second group is more heterogeneous, probably represented by a number of incipient species with different levels of genetic divergence among the siblings that produce different combinations of copulation songs and pheromones. The high level of complexity observed raises important questions concerning the epidemiological consequences of this incipient speciation process.

There is mounting evidence that the sandfly Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) (Lutz and Neiva 1912), the main vector of the visceral leishmaniasis in Latin America, is a complex of sibling species (Lanzaro et al. 1993 ; Dujardin et al. 1997 ; Lampo et al. 1999 ; Uribe 1999 ; Arrivillaga and Feliciangeli 2001 ; Soto et al. 2001 ). But, the evidence for Brazilian populations is still contradictory. Crossing experiments, pheromonal (Ward et al. 1983 , 1988 ; Hamilton et al. 1999a , 1999b ), copulation songs (Souza et al. 2002 ) and molecular analyses (Bauzer et al. 2002 ) all support the idea of a species complex and seem to confirm the data obtained for other populations of this species. But work with isoenzyme loci suggests that although it is a highly polymorphic and geographically variable species, L. longipalpis should not be considered a species complex in Brazil (Mukhopadhyay et al. 1998b ; Mutebi et al. 1999 ; Azevedo et al. 2000 ).