A microsatellite-based analysis of house infestation with Triatoma infestans (Hemiptera: Reduviidae) after insecticide spraying in the Argentine Chaco

PICCINALI RV; GAUNT MW; GÜRTLER RE

JOURNAL OF MEDICAL ENTOMOLOGY

ENTOMOLOGICAL SOC AMER

Lugar: Lanham; Año: 2018 vol. 55 p. 619 - 629

0022-2585

Prevention of vector-borne transmission of Chagas disease mainly relies on residual insecticide spraying. Despitesignificant success at a regional scale, house infestation with Triatoma infestans (Klug) (Hemiptera: Reduviidae) stillpersists in the Gran Chaco ecoregion. One key aspect is the identification of the sources of reinfestant triatomines.After detecting fine-scale genetic structure in two rural villages of Pampa del Indio, Argentine Chaco, we testedhypotheses on the putative origins of the triatomines collected at 4, 8, and 12 mo after insecticide house spraying.We genotyped 10 microsatellite loci in 262 baseline and 83 postspraying triatomines from different houses.Genetic variability was similar between baseline and postspraying populations, but 13 low-frequency alleleswere not detected at postspraying. FSTs were not significant between insects collected before and after insecticidespraying at the same house in all but one case, and they clustered together in a neighbor-joining tree. A clusteringalgorithm detected seven genetic groups, four of them mainly composed of baseline and postspraying insectsfrom the same house. Assignment tests suggested multiple putative sources (including the house of collection)for most postspraying insects but excluded a house located more than 9 km from the study area. The origin ofthree triatomines was attributed to immigration from other unaccounted sources. Our study is compatible withthe hypothesis that house reinfestations in the Argentine Chaco are mostly related to residual foci (i.e., survivalof insects within the same community), in agreement with field observations, spatial analysis, and morphometricstudies previously published.