Molecular and behavioral differentiation among Brazilian populations of Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae)

Abstract

Background: 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.

Methodology/principal findings: 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.

Conclusions/significance: 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.

Figure 1. Sample sites and summary of the information available for the different copulation songs and main pheromone types from 14 different L. longipalpis populations from Brazil.

Copulation songs: Burst-type (B) and Pulse-types (P1, P2, P3, P4, and P5); Pheromone types: cembrene (Cemb), 9-methylgermacrene-B (Germ) and himachalene (Hima). Cemb-1 and Cemb-2 differ in the mass spectra shape and ion composition of the most abundant diterpene compounds . The copulations songs of Lapinha, Jacobina, Marajó, Natal and Sobral were previously described in , while the pheromone data for the populations of Lapinha, Jacobina, Jaíba, Natal, Marajó and Sobral were published in , –,.

Figure 2. Haplotype network of the L. longipalpis sequences from Estrela de Alagoas.

Estrela 1S (yellow) and Estrela 2S (green). Haplotypes from individuals with recorded copulation songs (B: Burst-type and P5: Pulse-type 5) and the number of sequences (in brackets) are shown. Curved lines represent alternative branching between haplotypes.

Figure 3. Haplotype network of the L. longipalpis sequences from Jaíba.

Jaíba 1S (orange), Jaíba 2S (light green). Haplotypes from individuals with recorded copulation songs (B: Burst-type and P4: Pulse-type 4) and the number of sequences (in brackets) are shown. Curved lines represent alternative branching between haplotypes.

Figure 4. Haplotype networks of the L. longipalpis haplotypes from Brazil.

Each L. longipalpis population is represented by one color. Each node (pie diagram) represents a unique haplotype (see Table S4). The number of sequences represented in each node is shown in brackets.