Scientific Evidence of Three Different Insecticide-Resistant Profiles in Triatoma infestans (Hemiptera: Reduviidae) Populations From Argentina and Bolivia

M. D. GERMANO; P. SANTO-ORIHUELA; G. ROCA-ACEVEDO; A. C. TOLOZA; C. VASSENA; M. I. PICOLLO; G. MOUGABURE-CUETO

JOURNAL OF MEDICAL ENTOMOLOGY

ENTOMOLOGICAL SOC AMER

Lugar: Lanham; Año: 2012 vol. 49 p. 1355 - 1360

0022-2585

ABSTRACT Triatoma infestans (Klug, 1834) (Hemiptera, Reduviidae) is the main vector of Chagas disease in the southern cone South America. Chemical control to the vectors appears to be the best option to reduce the incidence of the disease. However, since 2002, high resistance to insecticides that correlated with Þeld control failures was detected in T. infestans from Argentina and Bolivia. In this paper, we analyzed three T. infestans populations whose pyrethroid-resistance had been recentlydetected, andwedeÞned at least three resistant proÞles according to the toxicological and biochemical characteristics of the studied resistant populations. The resistance proÞles were identiÞed as Ti-R1, Ti-R2, and Ti-R3, corresponding to the Argentinean Acambuco, and the Bolivians Entre Rõ´os and Mataral. Ti-R1 exhibited nymphs and eggs with medium resistance level to deltamethrin (RR 32.5 and 28.6; respectively). Pyrethroid-esterases played a relevant role in deltamethrin resistance. Ti-R2 exhibited nymphs with high resistance to deltamethrin (RR 173.8) and low resistance to Þpronil(RR 12.4). Pyrethroid-esterases were involved in resistance. Moreover, eggs showed medium resistance level to deltamethrin (RR 39.1). Ti-R3 had nymphs with low resistance to deltamethrin (RR 17.4), and medium resistance to Þpronil (RR 66.8). Pyrethroid-esterases showed increased activity, and eggs possessed low resistance to deltamethrin (RR 8.4). The characterization of the resistance to pyrethroid in these T. infestans populations from Argentina and Bolivia do not permit the generalization of three forms of resistance proÞle. So far as we appear to know, the forms of mechanisms and their frequencies reported here are selected independently, so additional sites might well show additional combinations of resistance mechanisms and their frequencies.