Geographical Variation of Deltamethrin Susceptibility of Triatoma infestans (Hemiptera: Reduviidae) in Argentina With Emphasis on a Resistant Focus in the Gran Chaco

G. FRONZA; A.C. TOLOZA; M.I. PICOLLO; C. SPILLMANN; G. MOUGABURE CUETO

JOURNAL OF MEDICAL ENTOMOLOGY

ENTOMOLOGICAL SOC AMER

Lugar: Lanham; Año: 2016 vol. 53 p. 880 - 887

0022-2585

Chagas disease is one of the most important parasitic infections in Latin America. The main vector of the protozoanTrypanosoma cruzi in America is Triatoma infestans, a blood-sucking triatomine bug who is widely distributedin the Gran Chaco ecoregion. Control programs in endemic countries are focused in the elimination of triatominevectors with pyrethroid insecticides. However, chemical control has failed in the Gran Chaco over thelast two decades because of several factors. Previous studies have reported the evolution of different levels ofresistance to deltamethrin in Tri. infestans. Recently, very high resistance has been found in the central area ofthe Argentine Gran Chaco. However, the origin and the extension of this remarkably resistant focus remain unknown.The aim of this study was to evaluate the geographical variation of deltamethrin susceptibility ofTri. infestans in different endemic provinces of Argentina, with emphasis in the center of the Argentine GranChaco ecoregion where this main vector has not been reduced. Populations of Mendoza, San Juan, Santiagodel Estero, and Tucuman provinces were all susceptible. Resistant populations were only detected in the provinceof Chaco, where a mosaic resistant focus was described at the Gu¨ emes Department. It was characterizedinto three pyrethroid resistance categories: susceptible, low, and highly resistant populations. We found thepopulations with the highest resistance levels to deltamethrin, with resistant ratios over 1000.