Assessing the mitochondrial DNA diversity of the Chagas disease vector Triatoma sordida (Hemiptera: Reduviidae)

Abstract

Triatoma sordida is a species that transmits Trypanosoma cruzi to humans. In Brazil, T. sordida currently deserves special attention because of its wide distribution, tendency to invade domestic environments and vectorial competence. For the planning and execution of control protocols to be effective against Triatominae, they must consider its population structure. In this context, this study aimed to characterise the genetic variability of T. sordida populations collected in areas with persistent infestations from Minas Gerais, Brazil. Levels of genetic variation and population structure were determined in peridomestic T. sordida by sequencing a polymorphic region of the mitochondrial cytochrome b gene. Low nucleotide and haplotype diversity were observed for all 14 sampled areas; π values ranged from 0.002-0.006. Most obtained haplotypes occurred at low frequencies, and some were exclusive to only one of the studied populations. Interpopulation genetic diversity analysis revealed strong genetic structuring. Furthermore, the genetic variability of Brazilian populations is small compared to that of Argentinean and Bolivian specimens. The possible factors related to the reduced genetic variability and strong genetic structuring obtained for studied populations are discussed in this paper.

Genetic Structure of Brazilian Populations of Triatoma sordida (Stål, 1859) (Hemiptera, Triatominae) by Means of Chromosomal Markers

“…These results are important because the chromosomal markers enable confirming and expanding the results described by Pessoa et al 23 and Monteiro et al 22 for all Brazilian states occupied by T. sordida. In addition, the low genetic diversity can also be confirmed by the low genetic distance observed between T. sordida from different Brazilian states [e.g., 0.011 among populations of Mato Grosso (Pocotó) and Mato Grosso do Sul (Pantanal) with the cytochrome oxidase I gene; 0.007 among populations of Mato Grosso (Rondonópolis) and Mato Grosso do Sul (Pantanal) with cytochrome oxidase II gene; and 0.006 among populations from municipalities in the state of Mato Grosso (Rondonópolis and Pocotó), and 0.004 and 0.002 distance observed between Rondonópolis and Pantanal and Pocotó and Pantanal, respectively, both with the 16S r DNA gene] 29 and by the low variability of the wing geometry of T. sordida observed recently among populations from Brazil.…”

“…[19][20][21] Furthermore, there are few studies that analyzed the genetic structure and genetic variability of specimens from Minas Gerais, Brazil, that showed low genetic diversity and strong genetic structuring of the population samples. 22,23 Recently, Pessoa et al 23 related low genetic diversity and strong genetic structuring of the population samples of T. sordida with five possible factors: possible geographical isolation due to an obstacle to Triatominae flow between neighboring localities; focal distribution of insects in small colonies usually comprised a few individuals, thereby limiting gene flow between them; the low dispersal capacity of T. sordida; the long Triatominae life cycle, which ensures that contributions from young adults able to reproduce (and consequently exchange genetic material) occurs over long intervals that differ among triatomine species; and continuous pressure from insecticides used since the 1950s to triatomines control.…”