Fine-scale population structure of Triatoma infestans in the Argentine Chaco.

PICCINALI RV; GURTLER RE

Infection, Genetics and Evolution

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 34 p. 143 - 152

1567-1348

The patterns of genetic structure in natural populations provide essential information for the improvement of pest management strategies including those targeting arthropod vectors of human diseases. We analyzed the patterns of fine-scale genetic structure in Triatoma infestans in a well-defined rural area close to Pampa del Indio, in the Argentine Arid-Humid Chaco transition, where a longitudinal study on house infestation and wing geometric morphometry is being conducted since 2007. A total of 228 insects collected in 16 domestic and peridomestic sites from two rural communities was genotyped for 10 microsatellite loci and analyzed. We did not find departures from Hardy-Weinberg expectations in collection sites, with three exceptions probably due to null alleles and substructuring. Domestic sites were more variable than peridomestic sites. Significant genetic structure was detected using F-statistics, a discriminant analysis of principal components and Bayesian clustering algorithms, with five sites consistently recovered as separate groups. These sites are the most suitable candidates for detecting the origins of house reinfestation. The incorporation of spatiality to the clustering analysis allowed the discrimination of a more subtle structuring pattern. A significant, although weak correlation between geographic and genetic distances was found, suggesting that the spatial distribution of genetic variability is more properly explained by an hierarchical island than an isolation-by-distance model. Microsatellite markers detected population structuring at a finer geographic scale (180-6,300 m) than a previous study based on wing geometric morphometry ( 4,000 m). This study illustrates that, despite more than a decade without vector control interventions, genetic structure can be detected in T. infestans populations. This supports the potential of genetic studies to provide key information for hypothesis testing of the origins of house reinfestation.