Characterizing the molecular and metabolic mechanisms of insecticide resistance in <i>Anopheles gambiae</i> s.l. in Faranah, Guinea

Stica, Caleb; Jeffries, Claire L.; Irish, Seth R.; Barry, Yaya; Camara, Denka; Yansane, Ismael; Kristan, Mojca; Walker, Thomas; Messenger, Louisa A.

doi:10.1101/610998

Cited by 2 publications

(3 citation statements)

References 25 publications

(33 reference statements)

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“…Other studies in Faranah Prefecture of Guinea with 100 µg AI/bottle produced 100% mortality with wild An. gambiae s.s., while in the Agréby-Tiassa Region of south-east Côte d'Ivoire, the same concentration produced only 95.5% mortality [36,37]. Using the formula of Lees et al it was determined that 200 µg AI/bottle was a suitable discriminating concentration and this concentration is likely to produce fewer cases of false resistance reporting than with 100 µg AI/bottle.…”

Section: Discussionmentioning

confidence: 99%

Determination of the discriminating concentration of chlorfenapyr (pyrrole) and Anopheles gambiae sensu lato susceptibility testing in preparation for distribution of Interceptor® G2 insecticide-treated nets

Oxborough

Seyoum

Yihdego

et al. 2021

Malar J

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Background Following agricultural use and large-scale distribution of insecticide-treated nets (ITNs), malaria vector resistance to pyrethroids is widespread in sub-Saharan Africa. Interceptor® G2 is a new dual active ingredient (AI) ITN treated with alpha-cypermethrin and chlorfenapyr for the control of pyrethroid-resistant malaria vectors. In anticipation of these new nets being more widely distributed, testing was conducted to develop a chlorfenapyr susceptibility bioassay protocol and gather susceptibility information. Methods Bottle bioassay tests were conducted using five concentrations of chlorfenapyr at 12.5, 25, 50, 100, and 200 µg AI/bottle in 10 countries in sub-Saharan Africa using 13,639 wild-collected Anopheles gambiae sensu lato (s.l.) (56 vector populations per dose) and 4,494 pyrethroid-susceptible insectary mosquitoes from 8 colonized strains. In parallel, susceptibility tests were conducted using a provisional discriminating concentration of 100 µg AI/bottle in 16 countries using 23,422 wild-collected, pyrethroid-resistant An. gambiae s.l. (259 vector populations). Exposure time was 60 min, with mortality recorded at 24, 48 and 72 h after exposure. Results Median mortality rates (up to 72 h after exposure) of insectary colony mosquitoes was 100% at all five concentrations tested, but the lowest dose to kill all mosquitoes tested was 50 µg AI/bottle. The median 72-h mortality of wild An. gambiae s.l. in 10 countries was 71.5, 90.5, 96.5, 100, and 100% at concentrations of 12.5, 25, 50, 100, and 200 µg AI/bottle, respectively. Log-probit analysis of the five concentrations tested determined that the LC95 of wild An. gambiae s.l. was 67.9 µg AI/bottle (95% CI: 48.8–119.5). The discriminating concentration of 203.8 µg AI/bottle (95% CI: 146–359) was calculated by multiplying the LC95 by three. However, the difference in mortality between 100 and 200 µg AI/bottle was minimal and large-scale testing using 100 µg AI/bottle with wild An. gambiae s.l. in 16 countries showed that this concentration was generally suitable, with a median mortality rate of 100% at 72 h. Conclusions This study determined that 100 or 200 µg AI/bottle chlorfenapyr in bottle bioassays are suitable discriminating concentrations for monitoring susceptibility of wild An. gambiae s.l., using mortality recorded up to 72 h. Testing in 16 countries in sub-Saharan Africa demonstrated vector susceptibility to chlorfenapyr, including mosquitoes with multiple resistance mechanisms to pyrethroids.

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Section: Discussionmentioning

confidence: 99%

Determination of the discriminating concentration of chlorfenapyr (pyrrole) and Anopheles gambiae sensu lato susceptibility testing in preparation for distribution of Interceptor® G2 insecticide-treated nets

Oxborough

Seyoum

Yihdego

et al. 2021

Malar J

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“…Anopheles adult mosquitoes were collected from two regions in Guinea. Human landing catches (HLCs) and larval dipping were conducted in three villages in the Faranah Prefecture; Balayani (10.1325, −10.7443), Foulaya (10.144633, −10.749717), and Tindo (9.9612230, −10.7016560) [33]. Three districts were selected for mosquito collections in the Maferinyah sub-prefecture using a variety of traps [34].…”

Section: Methodsmentioning

confidence: 99%

“…BG sentinel 2 traps (BG2) (Biogents), CDC light traps (John W. Hock), gravid traps (BioQuip) and stealth traps (John W. Hock) were used to sample adult mosquitoes in Maferinyah Centre (09.54650, −013.28160), Senguelen (09.41150, −013.37564) and Fandie ( 09.53047, −013.24000). Mosquitoes collected from traps and HLCs were morphologically identified using keys and stored in RNAlater® (Invitrogen) at −80°C [33,34].…”

Section: Methodsmentioning

confidence: 99%

Evidence for natural hybridisation and novel Wolbachia strain superinfections in the Anopheles gambiae complex from Guinea

Jeffries

Cansado-Utrilla

Béavogui³

et al. 2019

Preprint

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Background: Wolbachia, a widespread bacterium that can influence mosquitoborne pathogen transmission, has recently been shown to infect Anopheles (An.) species that are malaria vectors in Sub-Saharan Africa. Although there are studies reporting strains in the An. gambiae complex, the apparent low density and low prevalence rates requires further investigation. In contrast, strains in other species appear higher density allowing a greater understanding of phylogenetics and more accurate determination of prevalence rates in wild mosquito populations. Methods:Anopheles mosquitoes were collected in the Faranah and Maferinyah regions of Guinea in June-July 2018. RNA was extracted from 542 females and reverse transcribed to determine Wolbachia prevalence rates, demonstrate gene expression and estimate relative strain densities using quantitative PCR. Molecular confirmation of mosquito species and Wolbachia multilocus sequence typing (MLST) was carried out to analyse phylogenetic relationships of newly discovered strains.Results: Low prevalence rates were detected in An. gambiae s.s. (0.0: 2.9%) andnovel Wolbachia strains were discovered in two species: the wAnMe strain in An. melas (18/168: prevalence rate of 10.7%) and the wAnsX strain in a previously unidentified Anopheles species we have termed 'An. species X' (1/1). Novel strains were phylogenetically diverse, with wAnMe clustering with Wolbachia Supergroup A strains, and wAnsX closest to Supergroup B strains. Significantly higher density strains were present in An. species X and An. melas compared to An. gambiae s.s. and were comparable in density to a novel Wolbachia strain discovered in Culex watti termed wWat. Conclusions:The discovery of novel Wolbachia strains provides further insight into the strain diversity within Anopheles species. Confirmation of gene expression for all MLST and wsp genes for wAnsX and wAnMe strains and qPCR analysis indicates these are candidate strains for transinfection to create stable infections in other Anopheles species. They have the potential for use in Anopheles biocontrol strategies either through population replacement or suppression control strategies.

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Characterizing the molecular and metabolic mechanisms of insecticide resistance in Anopheles gambiae s.l. in Faranah, Guinea

Cited by 2 publications

References 25 publications

Determination of the discriminating concentration of chlorfenapyr (pyrrole) and Anopheles gambiae sensu lato susceptibility testing in preparation for distribution of Interceptor® G2 insecticide-treated nets

Determination of the discriminating concentration of chlorfenapyr (pyrrole) and Anopheles gambiae sensu lato susceptibility testing in preparation for distribution of Interceptor® G2 insecticide-treated nets

Evidence for natural hybridisation and novel Wolbachia strain superinfections in the Anopheles gambiae complex from Guinea

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