Residual effect of a micro-encapsulated formulation of organophosphates and piriproxifen on the mortality of deltamethrin resistant Triatoma infestans populations in rural houses of the Bolivian Chaco region

Abstract

The Bolivian Chaco is part of the endemic region of Chagas disease and an area where pyrethroid resistant Triatoma infestans (Hemiptera: Reduviidae) populations has been reported. The World Health Organization identified these resistant populations as an important focus for research. The objective of this study was to evaluate the residual effect of a micro-encapsulated formulation containing organophosphate active ingredients and a juvenile hormone analogue (Inesfly 5A IGR) on the mortality of T. infestans. Studies took place in rural houses of the Bolivian Chaco that were treated up to 34 months before and evaluated the susceptibility to pyrethroids of the offspring of field collected insects. Thirty houses were randomly selected within three communities to carry out wall bio-assays with T. infestans nymphs. Mortality was recorded 24, 48 and 72 h after wall contact. Eggs laid by females collected in the area were used to obtain first-instar nymphs and carry out pyrethroid susceptibility tests. The wall bio-assays showed that the micro-encapsulated insecticide eliminates T. infestans populations and produces detectable mortality of insects exposed to walls treated 34 months prior to the tests. The discriminant dose of deltamethrin (0.01 mg/mL) showed 65% nymph survival, whereas at the highest tested dose (1.0 mg/mL) 14% of the nymphs survived. These results show that Inesfly 5A IGR is an appropriate tool for the elimination of intradomestic and peridomestic populations of T. infestans resistant to pyrethroids

Susceptibility and resistance to deltamethrin of wild and domestic populations of Triatoma infestans (Reduviidae: Triatominae) in Bolivia: new discoveries

“…Previous data showed that resistance of domestic T. infestans to deltamethrin is widespread, high in Argentina (Vassena & Picollo 2003, Audino et al 2004) and particularly high in Bolivia, where the highest levels of resistance were observed in the department of Tarija (Alarico et al 2010, Germano et al 2010, Lardeux et al 2010). The present results confirmed this tendency, with the highest RR observed in the domestic population of Taiguati (RR = 818), a colony of approximately 25 specimens collected in a henhouse.…”

“…the broad distribution of deltamethrin resistance, with particularly high levels in the south of the country near Argentina (Alarico et al 2010, Lardeux et al 2010.…”

Susceptibility to deltamethrin of wild and domestic populations of Triatoma infestans of the Gran Chaco and the Inter-Andean Valleys of Bolivia

“…It is considered that vector control failures, are due to high levels of insecticide resistance in this area [18][19][20][21]. In the last few years, more studies demonstrated that the phenomenon of resistance to insecticides in domestic T. infestans populations presents an extensive distribution in southern Bolivia and northern Argentina [21][22][23], with high resistance ratios, and different toxicological profiles [14,18,19,[24][25][26]. Recently, susceptibility and resistance to deltamethrin and fipronil were detected in wild populations of T. infestans from Bolivia [14,27].…”

Pesticidal Paints: An Integral Approach to Colour your Imagination

“…1 It is argued that the slow-release mechanisms enable uniform AI surface concentrations with prolonged residual effect, as compared to earlier PP products using a simple admixture of AIs in standard paint formulations. 2 Depending on the chemical action of the embedded AIs, PPs may display different properties, including spatial repellency, contact irritancy, toxicity, insecticide synergy, or insect growth regulation. Importantly, different AIs can be combined in a single PP to ensure different modes of action in one product.…”