Abstract
BackgroundThe protozoan Trypanosoma cruzi circulates in semiarid areas of northeastern Brazil in distinct ecotopes (sylvatic, peridomestic and domestic) where Triatoma brasiliensis Neiva, 1911 is the most important Chagas disease vector. In this study, we analyzed microevolutionary and demographic aspects of T. brasiliensis populations at the ecotypic, micro and macro-geographic scales by combining morphometrics and molecular results. Additionally, we aimed to address the resolution of both markers for delimiting populations in distinct scales.MethodsWe sampled populations of T. brasiliensis from distinct ecotypic and geographic sites in the states Rio Grande do Norte (RN) and Paraíba (PB). The geometric morphometry was carried out with 13 landmarks on the right wings (n = 698) and the genetic structure was assessed by sequencing a region of cytochrome b mitochondrial gene (n = 221). Mahalanobis distance (MD) and coefficient of molecular differentiation (ΦST) were calculated among all pairs of populations. The results of comparisons generated MD and ΦST dendrograms, and graphics of canonical variate analysis (CVA).ResultsLittle structure was observed for both markers for macro-geographic scales. Mantel tests comparing geographic, morphometric and genetic matrices showed low correlation (all R2 < 0.35). The factorial graphics built with the CVA evidenced population delimitation for the morphometric data at micro-geographic scales.ConclusionsWe believe that T. brasiliensis carries in its genotype a source of information to allow the phenotypical plasticity across its whole distribution for shaping populations, which may have caused a lack of population delimitation for CVAs in morphometric analysis for macro-geographic scale analysis. On the other hand, the pattern of morphometric results in micro-geographic scales showed well-defined groups, highlighting the potential of this tool to inferences on the source for infestation.
Highlights
The protozoan Trypanosoma cruzi circulates in semiarid areas of northeastern Brazil in distinct ecotopes where Triatoma brasiliensis Neiva, 1911 is the most important Chagas disease vector
Insects Triatomine captures were conducted in the State of Rio Grande do Norte (RN), in the municipalities of Caicó, Currais Novos and Marcelino Vieira, whereas in the State of Paraíba (PB), insects were collected in the municipalities of Condado, Cajazeiras, Santa Teresinha, São José de Espinharas, São Mamede and Emas (Fig. 1)
The most remarkable result obtained here was the resolution in the population delimitation on a microgeographical scale for geometric morphometrics, which was sometimes in agreement with the results of molecular variation
Summary
The protozoan Trypanosoma cruzi circulates in semiarid areas of northeastern Brazil in distinct ecotopes (sylvatic, peridomestic and domestic) where Triatoma brasiliensis Neiva, 1911 is the most important Chagas disease vector. The transmission classically occurs via vector insects of the subfamily Triatominae (Hemiptera: Heteroptera: Reduviidae) These insect vectors may transmit the disease when they are infected with the parasite Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida: Trypanosomatidae), the etiological agent of the illness. The Brazilian Northeast, one of the poorest and underdeveloped regions of the country, raises concern in the context of Chagas disease transmission because it is an area of infestation by T. brasiliensis and T. pseudomaculata, native triatomines of difficult control and widespread in the semiarid Northeast. T. brasiliensis is the most frequently Chagas disease vector collected in human domiciles and is considered the most important triatomine species in the region [6]
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