Abstract:
The complete nucleotide sequences of the rDNA second internal transcribed spacer (ITS-2) of 7 populations of Triatoma infestans have been obtained by direct PCR cycle sequencing and the dideoxy chain-termination method. These domestic populations were obtained from the Cordillera, Paraguarí and Presidente Hayes departments of Paraguay. ITS-2 size was 458 base pairs, very similar to other species of the Triatomini tribe. All the Paraguayan insects exhibited an identical sequence, with an A+T content of 78%. When compared with the ITS-2 of T. infestans from Bolivia, 6 differences were identified: 2 transversions and 4 additional nucleotides resulting from an elongation of the microsatellite (AT)2. The secondary structure of the rRNA ITS-2 molecule has been obtained, showing an "L" form. Our data suggest an evolutionary divergence between the T. infestans populations from Bolivia and those from Paraguay, as the consequence of a time-space separation between them. Considering this species as originally from Bolivia, the genetic differences observed between Bolivian and Paraguayan populations and the absence of human migratory movements between Bolivia and Paraguay make a direct introduction from Bolivia unlikely, an indirect way through Argentina and/or Brazil being more plausible.
