"Andean" and "non-Andean" ITS-2 and mtCytB haplotypes of Triatoma infestans are observed in the Gran Chaco (Bolivia): population genetics and the origin of reinfestation.

In Bolivia, the Gran Chaco ecoregion suffers from serious problems of house reinfestation with Triatoma infestans despite vector control by insecticides spraying. In order to identify the origin of the triatomines collected after spraying, the genetic structure of T. infestans populations collected in four neighboring villages, before and after spraying, was analyzed using ITS-2 and mtCytB sequencing. Before spraying, only the mtCytB marker detected genetic differentiation among the 4 populations. After spraying, the mtCytB analysis of the populations from two of the studied villages supported the hypothesis in favor of a local origin for the triatomines in each village. Surprisingly, ITS-2 and mtCytB haplotypes previously found only in Andean areas were also present with high frequencies in the studied populations; these domestic populations of the Gran Chaco seem to be the result of a mixture of "Andean" and "non-Andean" triatomines probably generated by the human passive transport of triatomines from the Andes to the Gran Chaco.

New insights on the Chagas disease main vector Triatoma infestans (Reduviidae, Triatominae) brought by the genetic analysis of Bolivian sylvatic populations.

Triatoma infestans is the main and most widespread vector of Chagas disease in South America. For the first time, a large sample of sylvatic populations of T. infestans was analyzed by ITS-2 and mtCytB sequencing. ITS-2 showed a low level of polymorphism but revealed a dichotomy between the Andean and non-Andean sylvatic populations. On the contrary, mtCytB sequences showed a high polymorphism (19 haplotypes determined by 35 variable sites) revealing a strong structuring between most of the sylvatic populations and possible ancient isolation and bottleneck in the Northern Andes. The dichotomy Andean vs. non-Andean populations was not observed with this marker. Moreover, mtCytB haplotype genealogies showed that the non-Andean haplotypes would have derived from the Andean ones, supporting somewhat an Andean origin of the species. Nevertheless, a non-Andean origin could not be discarded because a remarkable genetic diversity was found in the non-Andean sample. The comparison of the sylvatic haplotypes with the domestic ones from GenBank suggested multiple events of T. infestans domestication in Andean and non-Andean areas, instead of a major and unique domestication event in the Bolivian Andes, as previously proposed.