Resistance to deltamethrin in Triatoma infestans: microgeographical distribution, validation of a rapid detection bioassay and evaluation of a fumigant canister as control alternative strategy

Abstract

Triatoma infestans (Klug) (Hemiptera: Reduviidae) is the main vector of Chagas disease in the Southern Cone of America and resistance to pyrethroid insecticides has been detected in several areas from its geographical distribution. Pyrethroid resistance presents a complex geographical pattern at different spatial scales. However, it is still unknown if the toxicological variability is a common feature within villages of the Gran Chaco were high resistance was descripted. The objectives of this study were to determine: (a) the microgeographical distribution of the deltamethrin-resistance in insects from Pampa Argentina village, (b) the performance of the insecticide impregnated paper bioassay to evaluate deltamethrin-resistance in field collected insects and (c) the lethal activity of the fumigant canister containing DDVP against insects resistant to deltamethrin. High survival of T. infestans exposed to discriminant dose was observed in the samples of all the evaluated dwellings, suggesting that the resistance to deltamethrin is homogeneous at the microgeographical level. Resistance determination by impregnated paper bioassay was similar to traditional topical determination, highlighting the use of this rapid methodology in field large-scale monitoring. The fumigant canister was not effective against resistant insects, remarking the need to develop suitable formulations that ensure minimal toxicological risk and high effectivity.

Treatment of dogs with fluralaner reduced pyrethroid-resistant Triatoma infestans abundance, Trypanosoma cruzi infection and human-triatomine contact in the Argentine Chaco

“…The immediate solution was to revert to organophosphates (fenitrothion, malathion) and carbamates (bendiocarb) despite their less than optimal safety profiles. Other alternatives investigated, including fipronil, imidacloprip, entomopathogenic fungi and dichlorvos (DDVP)-based fumigant canisters [ 13 ], were found to be efficacious against pyrethroid-resistant T. infestans but had limited residual activity [ 3 ]. Insecticidal paints, including chlorpyrifos, diazinon and pyriproxyfen, provided an effective and longer-lasting option than pyrethroids [ 14 , 15 ], but organophosphate-based paints have subsequently been restricted or phased out for residential use based on their neurotoxic effects with chronic low-dose exposure.…”

Slow recovery rates and spatial aggregation of Triatoma infestans populations in an area with high pyrethroid resistance in the Argentine Chaco

“…One includes a lack of studies integrating the spatiotemporal dynamics of triatomine populations in pyrethroid-resistant areas and detection of pyrethroid resistance at meaningful operational scales from sets of contiguous villages up to the district level. While there are examples of modeling infestation and control dynamics over a decade long in Cochabamba and Bolivia [ 81 ] and of detailed house distribution of RR 50 in a small village in Castelli [ 82 ], the challenge of addressing both processes simultaneously is still unmet. A second gap relates to the lack of understanding of the population-level impacts of pyrethroid resistance on triatomine infection and transmission of T. cruzi (see below).…”