Toxicity of non-pyrethroid insecticides against Triatoma infestans (Hemiptera: Reduviidae)

Guillermo Carvajal,Gastón Mougabure-Cueto,Ariel Ceferino Toloza

doi:10.1590/s0074-02762012000500015

Abstract

Triatoma infestans (Klug) is the main vector of Chagas disease, which is a public health concern in most Latin American countries. The prevention of Chagas disease is based on the chemical control of the vector using pyrethroid insecticides. In the last decade, different levels of deltamethrin resistance have been detected in certain areas of Argentina and Bolivia. Because of this, alternative non-pyrethroid insecticides from different chemical groups were evaluated against two T. infestans populations, NFS and El Malá, with the objective of finding new insecticides to control resistant insect populations. Toxicity to different insecticides was evaluated in a deltamethrin-susceptible and a deltamethrin-resistant population. Topical application of the insecticides fenitrothion and imidacloprid to first nymphs had lethal effects on both populations, producing 50% lethal dose (LD50) values that ranged from 5.2-28 ng/insect. However, amitraz, flubendiamide, ivermectin, indoxacarb and spinosad showed no insecticidal activity in first instars at the applied doses (LD50 > 200 ng/insect). Fenitrothion and imidacloprid were effective against both deltamethrin-susceptible and deltamethrin-resistant populations of T. infestans. Therefore, they may be considered alternative non-pyrethroid insecticides for the control of Chagas disease.

Highlights

Triatoma infestans (Klug) is the main vector of Chagas disease, which is a public health concern in most Latin American countries
The effect of non-pyrethroid insecticides was studied in the laboratory, with successful results being found for fipronil (Santo Orihuela et al 2008, Toloza et al 2008, Germano et al 2010, Roca Acevedo et al 2011), fenitrothion (Santo Orihuela et al 2008, Toloza et al 2008, Germano et al 2010) and ivermectin (Dias et al 2005)
The experimental results of the present study demonstrated high resistance to deltamethrin associated with ineffective field treatment of T. infestans in El Malá, which is located in the Chaco province of Argentina

Summary

Introduction

Triatoma infestans (Klug) is the main vector of Chagas disease, which is a public health concern in most Latin American countries. Fenitrothion and imidacloprid were effective against both deltamethrin-susceptible and deltamethrin-resistant populations of T. infestans They may be considered alternative non-pyrethroid insecticides for the control of Chagas disease. In the last decade, different levels of pyrethroid resistance have been detected in certain areas of Argentina and Bolivia (Picollo et al 2005, Santo Orihuela et al 2008, Toloza et al 2008, Germano et al 2010, Lardeux et al 2010) This lack of effectiveness of deltamethrin for the field control of T. infestans is observed mainly in the Gran Chaco ecoregion, there have been intensive vector control efforts in this area under the Southern Cone Initiative (Gürtler 2009). The effect of non-pyrethroid insecticides was studied in the laboratory, with successful results being found for fipronil (Santo Orihuela et al 2008, Toloza et al 2008, Germano et al 2010, Roca Acevedo et al 2011), fenitrothion (Santo Orihuela et al 2008, Toloza et al 2008, Germano et al 2010) and ivermectin (Dias et al 2005)

Methods

Results

Conclusion