The ITS-2 of the nuclear rDNA as a molecular marker for populations, species, and phylogenetic relationships in Triatominae (Hemiptera : Reduviidae),vectors of Chagas disease

The nucleotide sequences of the rDNA second internal transcribed spacer (IT S-S) of 31 populations of 12 and 3 species of the two main Triatominae trib es Triatomini and Rhodniini, including the most important Chagas disease ve ctors, were obtained, Sequence comparisons and parsimony, distance, and max imum-likelihood analyses indicate that ITS-S is a useful marker for resolvi ng supraspecific, specific, subspecific, and even sometimes population-leve l relationships in Triatominae. Results were markedly different between spe cies of Triatomini and Rhodniini, suggesting polyphyly. Phylogenetic trees support an old divergence between South American and North-Central American Triatomini and query the validity of some genera (Dipetalogaster, Psammole stes). The very low sequence variation between species of the phyllosoma co mplex suggests that subspecific ranking would be more appropriate. Triatoma dimidiata proves to be a clearly differentiated species, with several popu lations evidencing a clinal variation along a north-south axis and a popula tion from Yucatan showing differences consistent with specific status. (C) 2001 Academic Press.