Evolutionary relationships among North and Central American triatomines, vectors of Chagas disease

Chagas disease remains the most serious parasitic disease in Latin America with an estimated 10 million people currently infected with Trypanosoma cruzi, the causative agent. Most people become infected via triatomine insect vectors. Traditionally, taxonomists have attempted to classify the more than 130 species of triatomines by morphological characters to understand their evolutionary relationships and to infer the vector capacity of the species from their shared traits. Morphologically similar species have been organized into species complexes. Although the evolutionary relationships of many South American species have been inferred by extensive molecular studies, North and Central American species have received much less attention. The purpose of this study was to clarify the evolutionary relationships of 10 species of triatomines from North and Central America using two distinct molecular markers. A 339 base pair fragment of the 16S mitochondrial ribosomal subunit and the entire ITS-2 region of the nuclear rDNA (~500 base pairs) were used to infer evolutionary relationships of 10 species. Phylogenetic analysis reveals that the Phyllosoma complex is clearly separate from the remaining North and Central American species, and that the Dimidiata complex is most likely in the process of divergence from the Phyllosoma complex. The Lecticularia complex does not include T. sanguisuga, as was previously reported, and T. leticularia is most similar to Dipetalogaster maximus, thus calling into question the genus designation of Dipetalogaster. The remaining species fall within the Protracta and Rubida complexes. The 16S and ITS-2 produce similar topologies while ITS-2 provides higher resolution due to its faster mutation rate.