Variation in the Mitochondrial Genome of the Chagas Disease Vector Triatoma infestans (Hemiptera: Reduviidae).

Chagas' disease is transmitted mainly by members of the subfamily Triatominae (Hemiptera: Reduviidae). Among them, Triatoma infestans (Klug) is the main vector of the disease in Southern Cone of Latin America. In order to contribute to knowledge of the genetic variation between triatomine vectors, in the present study, we analyzed the intraspecific and interspecific variations of the seven mitogenomes available from Triatominae. In addition, in order to examine their evolutionary relationships with others species of Reduviidae and to estimate the divergence time of the main lineages, we constructed phylogenetic trees including mitogenome sequences of 30 species from Reduviidae. Comparative analysis between mitochondrial DNA sequences from two specimens of T. infestans revealed a total of 54 variable sites. Triatoma infestans, Triatoma dimidiata (Latreille), Triatoma rubrofasciata (De Geer), Triatoma migrans (Breddin), Rhodnius pictipes (Stål), and Panstrongylus rufotuberculatus (Champion) present similar mitogenome organization and the length differences observed among these species are primarily caused by variations in control region (CR) and intergenic spacers (IGS). The relative synonymous codon usage values (RSCU) were similar in the six species of Triatominae, and in agreement with the observed in other insects, a biased use of A and C nucleotides in the majority strand was detected. The monophyly of five subfamilies was strongly supported (Phymatinae, Peiratinae, Triatominae, Stenopodainae, and Harpactorinae), while the sampled species of Reduviinae were grouped with one specie from the Salyavatinae subfamily. The oldest subfamily is Phymatinae at 100.3 Mya (99.6-102.2 Mya) and the youngest is Triatominae and Stenopodainae at 52.6 Mya (42.5-63.7 Mya). The estimated diversification time for the Triatominae subfamily agrees with the Andean uplift geological event. An analysis with more mitogenomes from more Triatominae species would be necessary to provide sufficient evidence to support this finding.

Macrogeographic and microgeographic genetic structure of the Chagas' disease vector Triatoma infestans (Hemiptera: Reduviidae) from Catamarca, Argentina.

The genetic structure in populations of the Chagas' disease vector Triatoma infestans from six localities belonging to areas under the same insecticide treatment conditions of Catamarca province (Argentina) was examined at macrogeographical and microgeographical scales. A total of 238 insects were typed for 10 polymorphic microsatellite loci. The average observed and expected heterozygosities ranged from 0.319 to 0.549 and from 0.389 to 0.689, respectively. The present results confirm that populations of T. infestans are highly structured. Spatial genetic structure was detectable at macrogeographical and microgeographical levels. Comparisons of the levels of genetic variability between two temporal samples were carried out to assess the impact of the insecticide treatment. The genetic diversity of the population was not significantly affected after insecticide use since different genetic parameters (allele number, observed and expected heterozygosities) remained stable. However, loss of low frequency alleles and not previously found alleles were detected. The effective population size (N(e)) estimated was substantially lower in the second temporal sample than in the first; nevertheless, it is possible that the size of the remnant population after insecticide treatment was still large enough to retain the genetic diversity. Very few individuals did not belong to the local T. infestans populations as determined by assignment analyses, suggesting a low level of immigration in the population. The results of the assignment and first-generation migrant tests suggest male-biased dispersal at microgeographical level.