Lutzomyia umbratilis, the Main Vector of Leishmania guyanensis, Represents a Novel Species Complex?

BACKGROUND: Lutzomyia umbratilis is an important Leishmania guyanensis vector in South America. Previous studies have suggested differences in the vector competence between L. umbratilis populations situated on opposite banks of the Amazonas and Negro Rivers in the central Amazonian Brazil region, likely indicating a species complex. However, few studies have been performed on these populations and the taxonomic status of L. umbratilis remains unclear. METHODOLOGY/PRINCIPAL FINDINGS: Phylogeographic structure was estimated for six L. umbratilis samples from the central Amazonian region in Brazil by analyzing mtDNA using 1181 bp of the COI gene to assess whether the populations on opposite banks of these rivers consist of incipient or distinct species. The genetic diversity was fairly high and the results revealed two distinct clades ( = lineages) with 1% sequence divergence. Clade I consisted of four samples from the left bank of the Amazonas and Negro Rivers, whereas clade II comprised two samples from the right bank of Negro River. No haplotypes were shared between samples of two clades. Samples within clades exhibited low to moderate genetic differentiation (F(ST) = -0.0390-0.1841), whereas samples between clades exhibited very high differentiation (F(ST) = 0.7100-0.8497) and fixed differences. These lineages have diverged approximately 0.22 Mya in the middle Pleistocene. Demographic expansion was detected for the lineages I and II approximately 30,448 and 15,859 years ago, respectively, in the late Pleistocene. CONCLUSIONS/SIGNIFICANCE: The two genetic lineages may represent an advanced speciation stage suggestive of incipient or distinct species within L. umbratilis. These findings suggest that the Amazonas and Negro Rivers may be acting as effective barriers, thus preventing gene flow between populations on opposite sides. Such findings have important implications for epidemiological studies, especially those related to vector competence and anthropophily, and for vector control strategies. In addition, L. umbratilis represents an interesting example in speciation studies

Molecular taxonomy of the two Leishmania vectors Lutzomyia umbratilis and Lutzomyia anduzei (Diptera: Psychodidae) from the Brazilian Amazon

Background: Lutzomyia umbratilis (a probable species complex) is the main vector of Leishmania guyanensis in the northern region of Brazil. Lutzomyia anduzei has been implicated as a secondary vector of this parasite. These species are closely related and exhibit high morphological similarity in the adult stage; therefore, they have been wrongly identified, both in the past and in the present. This shows the need for employing integrated taxonomy. Methods. With the aim of gathering information on the molecular taxonomy and evolutionary relationships of these two vectors, 118 sequences of 663 base pairs (barcode region of the mitochondrial DNA cytochrome oxidase I - COI) were generated from 72 L. umbratilis and 46 L. anduzei individuals captured, respectively, in six and five localities of the Brazilian Amazon. The efficiency of the barcode region to differentiate the L. umbratilis lineages I and II was also evaluated. The data were analyzed using the pairwise genetic distances matrix and the Neighbor-Joining (NJ) tree, both based on the Kimura Two Parameter (K2P) evolutionary model. Results: The analyses resulted in 67 haplotypes: 32 for L. umbratilis and 35 for L. anduzei. The mean intra-specific genetic distance was 0.008 (0.002 to 0.010 for L. umbratilis; 0.008 to 0.014 for L. anduzei), whereas the mean interspecific genetic distance was 0.044 (0.041 to 0.046), supporting the barcoding gap. Between the L. umbratilis lineages I and II, it was 0.009 to 0.010. The NJ tree analysis strongly supported monophyletic clades for both L. umbratilis and L. anduzei, whereas the L. umbratilis lineages I and II formed two poorly supported monophyletic subclades. Conclusions: The barcode region clearly separated the two species and may therefore constitute a valuable tool in the identification of the sand fly vectors of Leishmania in endemic leishmaniasis areas. However, the barcode region had not enough power to separate the two lineages of L. umbratilis, likely reflecting incipient species that have not yet reached the status of distinct species. © 2013 Scarpassa and Alencar; licensee BioMed Central Ltd

Fauna de flebotomíneos (Diptera: Psychodidae) em um foco de leishmaniose tegumentar americana na área periurbana de Manaus, Estado do Amazonas Sandfly fauna (Diptera: Psychodidae) in a focus of American cutaneous leishmaniasis on the urban periphery of Manaus, State of Amazonas

No período de agosto de 2001 a julho de 2002, usando armadilhas CDC e Disney, realizaram-se coletas de flebotomíneos, na base de árvores no peridomicílio e nas matas da Comunidade São João, área periurbana de Manaus, Amazonas. Foram capturados 4.104 espécimes, pertencentes a quatro subtribos, 13 gêneros e 49 espécies da subfamília Phlebotominae. Predominou a subtribo Psychodopygina com 3.403 (83%) espécimes, destacando-se Nyssomyia umbratilis, Nyssomyia anduzei, Trichophoromyia eurypyga, Bichromomyia olmeca nociva e Bichromomyia flaviscutellata. O registro de Nyssomyia umbratilis e Nyssomyia anduzei, incriminadas como vetoras de Leishmania (Viannia) guyanensis, e de Bichromomyia flaviscutellata e Bichromomyia olmeca nociva, de Leishmania (Leishmania) amazonensis, indicam risco de infecção para os moradores da área. A grande maioria (98,5%) dos flebotomíneos foi capturada na área de mata. Nyssomyia anduzei e Bichromomyia olmeca nociva foram coletadas no peridomicílio. A riqueza de espécies vetoras de Leishmania nessa área revela a necessidade de uma vigilância entomológica constante.<br>From August 2001 to July 2002, sand flies were collected from the bases of trees and, using CDC and Disney traps, from areas surrounding homes and forested areas in the São João community, on the urban periphery of Manaus, State of Amazonas. 4,104 specimens belonging to four subtribes, 13 genera and 49 species of the Phlebotominae subfamily were collected. The subtribe Psychodopygina predominated, with 3,403 (83%) specimens, especially of Nyssomyia umbratilis, Nyssomyia anduzei, Trichophoromyia eurypyga, Bichromomyia olmeca nociva and Bichromomyia flaviscutellata. The occurrences of Nyssomyia umbratilis and Nyssomyia anduzei, which have been incriminated as vectors for Leishmania (Viannia) guyanensis, and of Bichromomyia flaviscutellata and Bichromomyia olmeca nociva, for Leishmania (Leishmania) amazonensis, indicate that there is a risk of infection for people living in this area. Most (98.5%) of the sand flies were caught in the forested area. Nyssomyia anduzei and Bichromomyia olmeca nociva were collected from areas surrounding homes. The richness of vector species for Leishmania in this area shows the need for constant entomological surveillance