Geographical distribution of deltamethrin susceptibility of Triatoma infestans in Argentina with emphasis on a resistant focus in the Gran Chaco

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

JOURNAL OF MEDICAL ENTOMOLOGY

ENTOMOLOGICAL SOC AMER

Lugar: Lanham; Año: 2016

0022-2585

Chagas disease is one of themost important parasitic infections in Latin America. The main vector of the protozoan T. cruzi in America isTriatoma infestans, a blood- suckingtriatomine bug who is widely distributed in the Gran Chaco ecorregion. Controlprogrammes in endemic countries rely primarily on elimination of domestictriatomine vectors with pyrethroid insecticides like deltamethrin. Chemicalcontrol has failed in the Gran Chaco over the last two decades as a consequenceof the development of insecticide resistance. Previous studies have reportedthe evolution of different levels of resistance to deltamethrin in T. infestans. Recently, very highresistance has been found in the central area of the Argentinian Gran Chaco.However, the origin and the extension of this remarkably resistant focus remainunknown. The aim of this work was to evaluate the geographical distribution ofdeltamethrin susceptibility of T.infestans in different endemic provinces of Argentina, with emphasis in thecenter of the Gran Chaco ecoregion where this main vector has not been reduced. Populations of Mendoza, SanJuan, Santiago del Estero and Tucumán provinces were all susceptible. Resistantpopulations were located only in the province of Chaco, where a very complexresistant focus was described at Güemes Department. It was characterized bythree different pyrethroid resistant categories: susceptible, low and highresistant populations, the latter with the highest resistance levels todeltamethrin, with RR values exceeding 1000. We discuss its implications forchemical control in this particularly problematic area in reference to theevolution of insecticide resistance.