Where do these bugs come from? Phenotypic structure of Triatoma infestans populations after control interventions in the Argentine Chaco

GASPE MS; PROVECHO YM; PICCINALI RV; GÜRTLER RE

MEMóRIAS DO INSTITUTO OSWALDO CRUZ.

FUNDACO OSWALDO CRUZ

Lugar: Rio de Janeiro; Año: 2015 vol. 110 p. 310 - 318

0074-0276

House re-invasion by native triatomines after insecticide-based control campaigns represents a major threat for Chagas disease vector control. We conducted a longitudinal intervention study in a rural section (Area III, 407 houses) of Pampa del Indio, northeastern Argentina, and used wing geometric morphometry to compare pre-spray and post-spray (reinfestant bugs) Triatoma infestans populations. The community-wide spraying with pyrethroids reduced the prevalence of house infestation by T. infestans from 31.9% to <1% during a four-year follow-up, unlike our previous studies in the neighboring Area I. Two groups of bug collection sites differing in wing shape variables before interventions (including 221 adults from 11 domiciles) were used as a reference for assigning 44 post-spray adults. Wing shape variables from post-spray, high-density bug colonies and pre-spray  groups  were significantly  different, suggesting that reinfestant insects had an external origin. Insects from one house differed strongly in wing shape variables from all other specimens. A further comparison between insects from both  Areas supported the existence of independent reinfestation processes within the same district. These results point to local heterogeneities in house reinfestation dynamics and emphasize  the need to expand the geographic coverage of vector surveillance and control operations to the affected region.