Antennal Phenotype ofTriatoma dimidiataPopulations and Its Relationship with Species ofphyllosomaandprotractaComplexes

Abstract

Triatoma dimidiata (Latreille 1811) Reduviidae Triatominae is the main vector of Chagas disease in several countries of Latin America. As for other vector species, the characterization of T. dimidiata subpopulations within particular geographical regions or occupying different habitats could help in better planning of vector control actions. A first objective in this study was to evaluate the antennal phenotype as a phenetic marker to characterize populations of T. dimidiata collected in different geographic areas and domestic and sylvatic habitats. A second objective was to evaluate the phenetic relationships of T. dimidiata with other species of the phyllosoma complex: longipennis, pallidipennis, and phyllosoma. The antennal sensilla of T. dimidiata specimens collected in Mexico, Central America, and Colombia were analyzed and compared with the antennal sensilla of T. longipennis, T. pallidipennis, and T. phyllosoma. T. barberi was used as an outgroup in the analysis. For each specimen, the ventral side of the three distal segments of the antennae was drawn, identifying and counting four types of sensilla. In T. dimidiata, univariate and multivariate analysis showed differences between sexes, among populations collected in different habitats within the same region, and among populations collected in different geographic regions. Two types of antennal sensilla showed a latitudinal variation. Domestic specimens showed intermediate characteristics of the antennal phenotype, between sylvatic cave- and sylvatic forest-collected specimens. The antennal phenotypes show high similarities among T. pallidipennis, T. phyllosoma, and T. longipennis, with a better differentiation of T. pallidipennis. T. dimidiata is separated from the other members of the complex by a similar distance to T. barberi, of the protracta complex.

Phylogeographic Pattern and Extensive Mitochondrial DNA Divergence Disclose a Species Complex within the Chagas Disease Vector Triatoma dimidiata

“…Studies based on morphometry [51], RAPD [52], antennal sensilla [53] and cuticular hydrocarbons [20], [54] of cave-dwelling specimens from Lanquín, Alta Verapaz, in Guatemala, revealed great phenotypic divergence from all other T. dimidiata populations analyzed. The differentiation was so remarkable that it was suggested that these insects could represent an incipient species [51], [54].…”

Phylogeography and Genetic Variation of Triatoma dimidiata, the Main Chagas Disease Vector in Central America, and Its Position within the Genus Triatoma

“…This study even revealed differences consistent with a specific status for populations from the Yucatan peninsula, Mexico [4]–[6], thus opening a debate. A large number of recent, multidisciplinary studies using RAPD-PCR, genital structures, morphometrics of head characters, and antennal phenotypes have shown that variation within this species seems much greater than previously considered [8], [12]–[16]. Morphometric and cuticular hydrocarbon analyses suggest that a sylvatic population from Lanquin, Guatemala, is undergoing a speciation process [13],[17].…”

Hypothesis testing clarifies the systematics of the main Central American Chagas disease vector, Triatoma dimidiata (Latreille, 1811), across its geographic range

“…These authors also noted that cave specimens differed from specimens collected outside the caves, similar to other arthropods, with “diminished pigmentation, reduction in size of eyes and ocelli, [and] longer head[s]”; however, a distinct taxonomic group was not suggested for the cave specimens as most of these are well-known environmentally-influenced modifications of cave dwellers. More recent work on antenna structure, head morphometry, and cuticular hydrocarbons has variously clustered T. dimidiata into two to four distinct taxa supporting the identification of unique cave populations, and identifying at least one cryptic species (by cuticular hydrocarbon analysis) (Bustamante et al, 2004; Calderón-Fernández et al, 2005; Calderón-Fernández et al, 2011; Catalá et al, 2005). So phenotypic results suggest one to four taxa.…”