Insecticide Resistance in Triatomines

Abstract

The control of Chagas disease vectors has been based principally on spraying dwellings with insecticides. This strategy reduced the geographic range and infestation prevalence of major vectors leading to the interruption of disease transmission in several areas from endemic regions. However, triatomine survival after spraying pyrethroid insecticides, mainly in the case of Triatoma infestans (Hemiptera: Reduviidae), has become more frequent in the last two decades. Insecticide resistance emerges as one main explanation for these chemical control failures. This chapter reviews the evolution of insecticide resistance in triatomines. Resistance to pyrethroids was first detected in T. infestans in the 1990s. But, it was only in the 2000s that resistance associated with control failures was described for the latter species in Argentina and Bolivia. Different resistant profiles were demonstrated for T. infestans suggesting that resistant foci originated independently. The main resistance mechanisms (i.e., enhanced detoxification, target-site modifications, and reduced penetration) were described for this species. Resistance to deltamethrin in T. infestans was shown to be controlled by an autosomal and incompletely dominant character. The resistance evolving in T. infestans from the Chaco ecoregion would be associated with different pleiotropic effects of the genes that confer resistance. Moreover, environmental variables linked to temperature and precipitation would explain part of the distribution of resistant populations of T. infestans in some endemic areas of the Chaco ecoregion. Finally, the possible resistance management strategies for triatomines are discussed.