Chlorfenapyr: a new insecticide with novel mode of action can control pyrethroid resistant malaria vectors

Abstract

BackgroundMalaria vectors have acquired widespread resistance to many of the currently used insecticides, including synthetic pyrethroids. Hence, there is an urgent need to develop alternative insecticides for effective management of insecticide resistance in malaria vectors. In the present study, chlorfenapyr was evaluated against Anopheles culicifacies and Anopheles stephensi for its possible use in vector control.MethodsEfficacy of chlorfenapyr against An. culicifacies and An. stephensi was assessed using adult bioassay tests. In the laboratory, determination of diagnostic dose, assessment of residual activity on different substrates, cross-resistance pattern with different insecticides and potentiation studies using piperonyl butoxide were undertaken by following standard procedures. Potential cross-resistance patterns were assessed on field populations of An. culicifacies.ResultsA dose of 5.0% chlorfenapyr was determined as the diagnostic concentration for assessing susceptibility applying the WHO tube test method in anopheline mosquitoes with 2 h exposure and 48 h holding period. The DDT-resistant/malathion-deltamethrin-susceptible strain of An. culicifacies species C showed higher LD50 and LD99 (0.67 and 2.39% respectively) values than the DDT-malathion-deltamethrin susceptible An. culicifacies species A (0.41 and 2.0% respectively) and An. stephensi strains (0.43 and 2.13% respectively) and there was no statistically significant difference in mortalities among the three mosquito species tested (p > 0.05). Residual activity of chlorfenapyr a.i. of 400 mg/m2 on five fabricated substrates, namely wood, mud, mud+lime, cement and cement + distemper was found to be effective up to 24 weeks against An. culicifacies and up to 34 weeks against An. stephensi. No cross-resistance to DDT, malathion, bendiocarb and deltamethrin was observed with chlorfenapyr in laboratory-reared strains of An. stephensi and field-caught An. culicifacies. Potentiation studies demonstrated the antagonistic effect of PBO.ConclusionLaboratory studies with susceptible and resistant strains of An. culicifacies and An. stephensi, coupled with limited field studies with multiple insecticide-resistant An. culicifacies have shown that chlorfenapyr can be a suitable insecticide for malaria vector control, in multiple-insecticide-resistant mosquitoes especially in areas with pyrethroid resistant mosquitoes.

Impact of insecticides used to control Spodoptera frugiperda (J.E. Smith) in corn on survival, sex ratio, and reproduction of Trichogramma pretiosum Riley offspring

“…Chlorfenapyr is a pro-insecticide member of the "pyrrole" chemical family, which must be converted into an active form before it can cause this effect by enzyme action called mixed function oxidases. The toxic form of chlorfenapyr, identified as CL 303268, uncouples oxidative phosphorylation in the mitochondria, which disrupts ATP (adenosine triphosphate) production and energy loss leading to cell dysfunction and subsequent insect death (Black et al, 1994;Sato et al, 2007;Raghavendra et al, 2011).…”

Caracterización de la transmisión de la malaria por Plasmodium vivax en la región fronteriza de Panamá con Costa Rica en el municipio de Barú, Panamá

“…Es posible que se presenten brotes de malaria no sólo en áreas tradicionalmente palúdicas, sino en aquellas que incluso han sido declaradas con anterioridad libres de la enfermedad (7). Es importante indicar que la reemergencia de la malaria en muchas regiones obedece a diferentes factores, entre ellos, cambios en las políticas de control de los programas de malaria, aspectos biológicos del huésped humano, el vector y el parásito, cambios en el medio ambiente y desarrollo de resistencia a los insecticidas en poblaciones de anofelinos vectores (2,8).…”

Determinación de la resistencia a insecticidas organofosforados, carbamatos y piretroides en tres poblaciones de Anopheles albimanus (Diptera: Culicidae) de Panamá

“…culicifacies y An. stephensi, ambas especies han desarrollado resistencia múltiple a insecticidas (16 (17,18). En Panamá, la malaria siempre ha representado un serio problema de salud pública, debido a su alto costo socioeconómico y es considerada la enfermedad reemergente más importante.…”