Effectiveness of Essential Oils and Their Components Against Triatoma infestans (Hemiptera: Reduviidae)

Abstract

Purpose of Review: Chagas disease is a neglected tropical disease caused by the protozoan parasite called Trypanosoma cruzi affecting 7–8 million people in the world. Triatoma infestans (Klug) (Hemiptera: Reduviidae) is the main vector of Chagas disease in the southern cone of South America. Genetic evidence indicates that T. infestans originated in the Cochabamba region, Sucre, in Central Bolivia, where there are jungle sites of this species, and from which the domestic species is believed to derive, currently distributed in Chile, Argentina, Brazil, Bolivia, and Paraguay. Chemical control of the vector by spraying dwellings with pyrethroids has been the most widely used strategy to reduce the incidence of this endemic disease. The long-term use of pyrethroid insecticides in T. infestans control campaigns has led to the development of resistance in treated populations. Recently, there has been great interest in the use of botanical products as new alternatives to synthetic insecticides. Essential oils (EOs) seem to be good candidates due to lesser mammalian toxicity and persistence in the environment. In this review, we summarize recent data on toxicity of EOs and their compounds against T. infestans. Recent Findings: A total of 12 research articles from different sources were reviewed and analyzed to compare the effectiveness of the studied EOs and monoterpenes on kissing bugs. The monoterpenes and the EOs reported in the experimental procedures and their effectiveness against T. infestans are described in Table 1. A total of 22 monoterpenes and 46 EOs were reported and distributed in 12 botanical families. Of these, 18 EOs belonged to the following families: Asteraceae, 8; Lamiaceae, 5; Apiaceae, 2; Anacardiaceae, 2; Buddlejaceae, 4; Verbenaceae, 2; and one each to Monimiaceae, Capparaceae, Umbelliferae, Myrtaceae, Fabaceae, and Labiatae. The main active components of the EOs responsible for the ovicidal and larvicidal properties on T. infestans were menthyl acetate, L-menthone, L-menthol, isomenthol, piperitone, linalool, pulegone, 1,8-cineole, α,β-thujone, limonene, E-anethol, and E-nerolidol. Moreover, the compounds eugenol, 1,8-cineole, linalool, menthol, α-terpineol, and thymol were the most effective inducing hyperactivity (disordered, erratic, and spasmodic locomotor activity). Reported effectiveness varied widely due to the difference in the evaluation methodology and properties of both EOs and monoterpenes. Some of the advantages of using EOs and monoterpenes are that they have little environmental impact because of their low toxicity to mammals and very low environmental persistence. An important finding was the reported synergism on the hyperactivity and mortality effect between eugenol and permethrin on T. infestans. Summary: In recent years, the toxicity of new essential oils and their compounds on T. infestans was evaluated, as well as combinations of monoterpenes with pyrethroids. The latter is the most promising result since it could be a new tool for monitoring the population dynamic. The findings of this work show that certain EOs and their components have insecticidal and repellent potential for their development as formulations for T. infestans. The production of EO is feasible due to its low cost, availability, and accessibility. It is difficult to compare the reported info from literature due to the wide variety of exposure bioassay techniques and chemical extraction methods of the EOs and their compounds. The synergistic effect between eugenol and permethrin on T. infestans suggests that this combination could be a viable alternative of the flushing-out strategy employed in the national control campaigns. Thus, essential oils and their constituents would contribute to delay the development of insecticide resistance in the populations of T. infestans through the combination of these actives with pyrethroids.