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Rhodnius ecuadoriensis is one of the most important vector species of Chagas disease in Ecuador. This species is distributed in the Central coast region and in the south Andean region, and an incipient speciation process between these geographical populations was previously proposed. The current population genetics study only focused on the Central coast region and analyzed 96 sylvatic specimens of R. ecuadoriensis associated with Phytelephas aequatorialis palm trees. We used Cytb and 16S-rRNA sequences and a Cytb-16S-rRNA concatenated set to explore (i) the genetic variability, spatial structuring, and demographic history of R. ecuadoriensis, and to determine (ii) the relationship between the genetic and climatic variabilities. A particularly high genetic variability was observed without detectable general genetic structure; only some terminal genetic clusters were observed. We did not observe isolation by geographical distance (IBD), and it is likely that ancient expansion occurred, according to Fs index and mismatch distribution for Cytb-16S-rRNA concatenated sequences. Hierarchical clustering showed that the current locality origins of the bugs were grouped into four bioclimatic clusters. Genetic and bioclimatic distances were not correlated, but some genetic clusters were associated with bioclimatic ones. The results showed an ancient evolution of the species in the region with a possible old expansion. The absence of spatial genetic structure could be due to climatic conditions (possible selection of singular genotypes) and to passive transportation of palms tree materials where R. ecuadoriensis are living.

Limited genetic data are currently available for three vectors of Chagas disease in Ecuador, Panstrongylus howardi, P. chinai, and P. rufotuberculatus. Previously regarded as mainly sylvatic, these species have been poorly studied. Recently, they have been more frequently reported in domiciles and peridomiciles and are now considered true secondary vectors of Chagas disease in a country where an estimated 200,000 people are infected by Trypanosoma cruzi, a causative agent of this disease. In order to fill this gap, we obtained DNA for sequencing from 53 insects belonging to these three species and mainly sampled from the two Ecuadorian provinces of Loja and Manabi. We used six mitochondrial loci (COI, COII, ND4, CytB, 16S, and 12S) and two nuclear ones (ITS2 and 18S). We interpreted the phylogenetic trees built with single and concatenated data through maximum likelihood, Bayesian Markov chain Monte Carlo, and maximum parsimony methods. We provide evidence that P. chinai and P. howardi are indeed two supported species closely related and derived from a common ancestor. Additionally, the phylogenetic position of P. rufotuberculatus was confirmed as being distant from P. chinai and P. howardi and clustered with Triatoma dimidiata, a species belonging to the Northern American Triatoma clade.

Effective control of Chagas disease vector populations requires a good understanding of the epidemiological components, including a reliable analysis of the genetic structure of vector populations. Rhodnius ecuadoriensis is the most widespread vector of Chagas disease in Ecuador, occupying domestic, peridomestic and sylvatic habitats. It is widely distributed in the central coast and southern highlands regions of Ecuador, two very different regions in terms of bio-geographical characteristics. To evaluate the genetic relationship among R. ecuadoriensis populations in these two regions, we analyzed genetic variability at two microsatellite loci for 326 specimens (n = 122 in Manabi and n = 204 in Loja) and the mitochondrial cytochrome b gene (Cyt b) sequences for 174 individuals collected in the two provinces (n - 73 and - 101 in Manabi and Loja respectively). The individual samples were grouped in populations according to their community of origin. A few populations presented positive F-IS, possible due to Wahlund effect. Significant pairwise differentiation was detected between populations within each province for both genetic markers, and the isolation by distance model was significant for these populations. Microsatellite markers showed significant genetic differentiation between the populations of the two provinces. The partial sequences of the Cyt b gene (578 bp) identified a total of 34 haplotypes among 174 specimens sequenced, which translated into high haplotype diversity (Hd = 0.929). The haplotype distribution differed among provinces (significant Fisher's exact test). Overall, the genetic differentiation of R. ecuadoriensis between provinces detected in this study is consistent with the biological and phenotypic differences previously observed between Manabi and Loja populations. The current phylogenetic analysis evidenced the monophyly of the populations of R. ecuadoriensis within the R. pallescens species complex; R. pallescens and R. colombiensis were more closely related than they were to R. ecuadoriensis.

Background Chagas disease is a parasitic infection transmitted by “kissing bugs” (Hemiptera: Reduviidae: Triatominae) that has a huge economic impact in Latin American countries. The vector species with the upmost epidemiological importance in Ecuador are Rhodnius ecuadoriensis (Lent & Leon, 1958) and Triatoma dimidiata (Latreille, 1811). However, other species such as Panstrongylus howardi (Neiva, 1911) and Panstrongylus chinai (Del Ponte, 1929) act as secondary vectors due to their growing adaptation to domestic structures and their ability to transmit the parasite to humans. The latter two taxa are distributed in two different regions, they are allopatric and differ mainly by their general color. Their relative morphological similarity led some authors to suspect that P. chinai is a melanic form of P. howardi. Methods The present study explored this question using different approaches: antennal phenotype; geometric morphometrics of heads, wings and eggs; cytogenetics; molecular genetics; experimental crosses; and ecological niche modeling. Results The antennal morphology, geometric morphometrics of head and wing shape and cytogenetic analysis were unable to show distinct differences between the two taxa. However, geometric morphometrics of the eggs, molecular genetics, ecological niche modeling and experimental crosses including chromosomal analyses of the F1 hybrids, in addition to their coloration and current distribution support the hypothesis that P. chinai and P. howardi are separate species. Conclusions Based on the evidence provided here, P. howardi and P. chinai should not be synonymized. They represent two valid, closely related species.