scholarly journals Genetic variation at the Cyp6m2 putative insecticide resistance locus in Anopheles gambiae and Anopheles coluzzii

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Martin G. Wagah ◽  
◽  
Petra Korlević ◽  
Christopher Clarkson ◽  
Alistair Miles ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Metabolic Activity ◽  
High Frequency ◽  
Cross Resistance ◽  
Resistance Locus ◽  
Anopheles Coluzzii ◽  
Metabolic Resistance ◽  
Enzymatic Function

Abstract Background The emergence of insecticide resistance is a major threat to malaria control programmes in Africa, with many different factors contributing to insecticide resistance in its vectors, Anopheles mosquitoes. CYP6M2 has previously been recognized as an important candidate in cytochrome P450-mediated detoxification in Anopheles. As it has been implicated in resistance against pyrethroids, organochlorines and carbamates, its broad metabolic activity makes it a potential agent in insecticide cross-resistance. Currently, allelic variation within the Cyp6m2 gene remains unknown. Methods Here, Illumina whole-genome sequence data from Phase 2 of the Anopheles gambiae 1000 Genomes Project (Ag1000G) was used to examine genetic variation in the Cyp6m2 gene across 16 populations in 13 countries comprising Anopheles gambiae and Anopheles coluzzii mosquitoes. To identify whether these alleles show evidence of selection either through potentially modified enzymatic function or by being linked to variants that change the transcriptional profile of the gene, hierarchical clustering of haplotypes, linkage disequilibrium, median joining networks and extended haplotype homozygosity analyses were performed. Results Fifteen missense biallelic substitutions at high frequency (defined as > 5% frequency in one or more populations) are found, which fall into five distinct haplotype groups that carry the main high frequency variants: A13T, D65A, E328Q, Y347F, I359V and A468S. Despite consistent reports of Cyp6m2 upregulation and metabolic activity in insecticide resistant Anophelines, no evidence of directional selection is found occurring on these variants or on the haplotype clusters in which they are found. Conclusion These results imply that emerging resistance associated with Cyp6m2 is potentially driven by distant regulatory loci such as transcriptional factors rather than by its missense variants, or that other genes are playing a more significant role in conferring metabolic resistance.

scholarly journals Genetic variation at the Cyp6m2 putative insecticide resistance locus in Anopheles gambiae and Anopheles coluzzii

2020 ◽  
Author(s):  
Martin G. Wagah ◽  
Petra Korlević ◽  
Christopher Clarkson ◽  
Alistair Miles ◽  
Mara K. N. Lawniczak ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Metabolic Activity ◽  
High Frequency ◽  
Cross Resistance ◽  
Resistance Locus ◽  
Anopheles Coluzzii ◽  
Metabolic Resistance ◽  
Enzymatic Function

AbstractBackgroundThe emergence of insecticide resistance is a major threat to malaria control programmes in Africa, with many different factors contributing to insecticide resistance in its vectors, Anopheles mosquitoes. CYP6M2 has previously been recognized as an important candidate in cytochrome P450-mediated detoxification in Anopheles mosquitoes. As it has been implicated in resistance against pyrethroids, organochlorines and carbamates, its broad metabolic activity makes it a potential agent in insecticide cross-resistance. Currently, allelic variation within the Cyp6m2 gene remains unknown.ResultsHere, we use Illumina whole-genome sequence data from Phase 2 of the Anopheles gambiae 1000 Genomes Project (Ag1000G) to examine genetic variation in the Cyp6m2 gene across 16 populations in 13 countries comprising Anopheles gambiae and Anopheles coluzzii mosquitoes. We find 15 missense biallelic substitutions at high frequency (defined as >5% frequency in one or more populations), that fall into five distinct haplotype groups that carry the main high frequency variants: A13T, D65A, E328Q, Y347F, I359V and A468S. We examine whether these alleles show evidence of selection either through potentially modified enzymatic function or by being linked to variants that change the transcriptional profile of the gene. Despite consistent reports of Cyp6m2 upregulation and metabolic activity in insecticide resistant Anophelines, we find no evidence of directional selection occurring on these variants or on the haplotype clusters in which they are found.ConclusionOur results imply that emerging resistance associated with Cyp6m2 is potentially driven by distant regulatory loci such as transcriptional factors rather than by its missense variants, or that other genes are playing a more significant role in conferring metabolic resistance.

scholarly journals Insecticide Resistance Profiling of Anopheles coluzzii and Anopheles gambiae Populations in the Southern Senegal: Role of Target Sites and Metabolic Resistance Mechanisms

Genes ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1403
Author(s):  
Oumou. K. Gueye ◽  
Magellan Tchouakui ◽  
Abdoulaye K. Dia ◽  
Mouhamed B. Faye ◽  
Amblat A. Ahmed ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Resistance Mechanisms ◽  
Target Site ◽  
World Health ◽  
Anopheles Coluzzii ◽  
Partial Recovery ◽  
Metabolic Resistance ◽  
Genes Expression ◽  
Main Target

The emergence and spread of insecticide resistance among the main malaria vectors is threatening the effectiveness of vector control interventions in Senegal. The main drivers of this resistance in the Anopheles gambiae complex (e.g., An. gambiae and Anopheles coluzzii) remains poorly characterized in Senegal. Here we characterized the main target site and metabolic resistances mechanisms among the An. gambiae and An. coluzzii populations from their sympatric and allopatric or predominance area in Senegal. Larvae and pupae of An. gambiae s.l. were collected, reared to adulthood, and then used for insecticides susceptibility and synergist assays using the WHO (World Health Organisation) test kits for adult mosquitoes. The TaqMan method was used for the molecular characterization of the main target site insecticide resistance mechanisms (Vgsc-1014F, Vgsc-1014S, N1575Y and G119S). A RT-qPCR (Reverse Transcriptase-quantitative Polymerase Chaine Reaction) was performed to estimate the level of genes expression belonging to the CYP450 (Cytochrome P450) family. Plasmodium infection rate was investigated using TaqMan method. High levels of resistance to pyrethroids and DDT and full susceptibility to organophosphates and carbamates where observed in all three sites, excepted a probable resistance to bendiocarb in Kedougou. The L1014F, L1014S, and N1575Y mutations were found in both species. Pre-exposure to the PBO (Piperonyl butoxide) synergist induced a partial recovery of susceptibility to permethrin and full recovery to deltamethrin. Subsequent analysis of the level of genes expression, revealed that the CYP6Z1 and CYP6Z2 genes were over-expressed in wild-resistant mosquitoes compared to the reference susceptible strain (Kisumu), suggesting that both the metabolic resistance and target site mutation involving kdr mutations are likely implicated in this pyrethroid resistance. The presence of both target-site and metabolic resistance mechanisms in highly pyrethroid-resistant populations of An. gambiae s.l. from Senegal threatens the effectiveness and the sustainability of the pyrethroid-based tools and interventions currently deployed in the country. The Kdr-west mutation is widely widespread in An. coluzzii sympatric population. PBO or Duo nets and IRS (Indoor Residual Spraying) with organophosphates could be used as an alternative measure to sustain malaria control in the study area.

scholarly journals Insecticide resistance in indoor and outdoor-resting Anopheles gambiae in Northern Ghana

2020 ◽  
Author(s):  
Majidah Hamid-Adiamoh ◽  
Alfred Amambua-Ngwa ◽  
Davis Nwakanma ◽  
Umberto D’Alessandro ◽  
Gordon A. Awandare ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Northern Ghana ◽  
Malaria Vectors ◽  
Anopheles Coluzzii ◽  
Glutathione S Transferase ◽  
Metabolic Resistance ◽  
Phenotypic Resistance ◽  
Resting Behaviour ◽  
Outdoor Resting

Abstract Background Selection pressure from continued exposure to insecticides drives development of insecticide resistance and changes in resting behaviour of malaria vectors. There is need to understand how resistance drives changes in resting behaviour within vector species. The association between insecticide resistance and resting behaviour of Anopheles gambiae sensu lato (s.l.) in Northern Ghana was examined. Methods F1 progenies from adult mosquitoes collected indoors and outdoors were exposed to DDT, deltamethrin, malathion and bendiocarb using WHO insecticide susceptibility tests. Insecticide resistance markers including voltage-gated sodium channel (Vgsc)- 1014F, Vgsc-1014S, Vgsc-1575Y, glutathione-S-transferase epsilon 2 (GSTe2)-114T and acetylcholinesterase (Ace1)-119S, as well as blood meal sources were investigated using PCR methods. Activities of metabolic enzymes, acetylcholine esterase (AChE), non-specific β-esterases, glutathione-S-transferase (GST) and monooxygenases were measured from unexposed F1 progenies using microplate assays. Results Susceptibility of Anopheles coluzzii to deltamethrin 24hr post-exposure was significantly higher in indoor (mortality=5%) than outdoor (mortality=2.5%) populations (P=0.02). Mosquitoes were fully susceptible to malathion (mortality: indoor=98%, outdoor=100%). Susceptibility to DDT was significantly higher in outdoor (mortality=9%) than indoor (mortality=0%) mosquitoes (P=0.006). Mosquitoes were also found with suspected resistance to bendiocarb but mortality was not statistically different (mortality: indoor=90%, outdoor=95%. P=0.30). Frequencies of all resistance alleles were higher in F1 outdoor (0.11-0.85) than indoor (0.04-0.65) mosquito populations, while Vgsc-1014F in F0 An. gambiae sensu stricto (s.s) was significantly associated with outdoor-resting behaviour (P=0.01). Activities of non-specific β-esterase enzymes were significantly higher in outdoor than indoor mosquitoes (Mean enzyme activity: Outdoor=: 1.70/mg protein; Indoor=1.35/mg protein. P<0.0001). AChE activity was also more elevated in outdoor (0.62/mg protein) than indoor (0.57/mg protein) mosquitoes but this was not significant (P=0.08). Human blood index (HBI) was predominantly detected in indoor (18%) than outdoor mosquito populations (3%). Conclusions The overall results did not establish that there was a significant preference of resistant malaria vectors to solely rest indoors or outdoors, but varied depending on the resistant alleles present. Phenotypic resistance was higher in indoor than outdoor-resting mosquitoes, but genotypic and metabolic resistance levels were higher in outdoor than the indoor populations. Continued monitoring of changes in resting behaviour within An. gambiae s.l. populations is recommended.

scholarly journals Evaluation of the interaction between insecticide resistance-associated genes and malaria transmission in Anopheles gambiae sensu lato in central Côte d’Ivoire

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Rosine Z. Wolie ◽  
Alphonsine A. Koffi ◽  
Ludovic P. Ahoua Alou ◽  
Eleanore D. Sternberg ◽  
Oulo N’Nan-Alla ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Malaria Transmission ◽  
Vector Competence ◽  
Quantitative Polymerase Chain Reaction ◽  
Sub Saharan Africa ◽  
Human Landing Catch ◽  
Anopheles Coluzzii ◽  
Metabolic Resistance ◽  
The Impact

Abstract Background There is evidence that the knockdown resistance gene (Kdr) L1014F and acetylcholinesterase-1 gene (Ace-1R) G119S mutations involved in pyrethroid and carbamate resistance in Anopheles gambiae influence malaria transmission in sub-Saharan Africa. This is likely due to changes in the behaviour, life history and vector competence and capacity of An. gambiae. In the present study, performed as part of a two-arm cluster randomized controlled trial evaluating the impact of household screening plus a novel insecticide delivery system (In2Care Eave Tubes), we investigated the distribution of insecticide target site mutations and their association with infection status in wild An. gambiae sensu lato (s.l.) populations. Methods Mosquitoes were captured in 40 villages around Bouaké by human landing catch from May 2017 to April 2019. Randomly selected samples of An. gambiae s.l. that were infected or not infected with Plasmodium sp. were identified to species and then genotyped for Kdr L1014F and Ace-1R G119S mutations using quantitative polymerase chain reaction assays. The frequencies of the two alleles were compared between Anopheles coluzzii and Anopheles gambiae and then between infected and uninfected groups for each species. Results The presence of An. gambiae (49%) and An. coluzzii (51%) was confirmed in Bouaké. Individuals of both species infected with Plasmodium parasites were found. Over the study period, the average frequency of the Kdr L1014F and Ace-1R G119S mutations did not vary significantly between study arms. However, the frequencies of the Kdr L1014F and Ace-1R G119S resistance alleles were significantly higher in An. gambiae than in An. coluzzii [odds ratio (95% confidence interval): 59.64 (30.81–131.63) for Kdr, and 2.79 (2.17–3.60) for Ace-1R]. For both species, there were no significant differences in Kdr L1014F or Ace-1R G119S genotypic and allelic frequency distributions between infected and uninfected specimens (P > 0.05). Conclusions Either alone or in combination, Kdr L1014F and Ace-1R G119S showed no significant association with Plasmodium infection in wild An. gambiae and An. coluzzii, demonstrating the similar competence of these species for Plasmodium transmission in Bouaké. Additional factors including behavioural and environmental ones that influence vector competence in natural populations, and those other than allele measurements (metabolic resistance factors) that contribute to resistance, should be considered when establishing the existence of a link between insecticide resistance and vector competence. Graphical Abstract

scholarly journals Phenotypic Insecticide Resistance in Anopheles gambiae (Diptera: Culicidae): Specific Characterization of Underlying Resistance Mechanisms Still Matters

2020 ◽  
Author(s):  
Adandé A Medjigbodo ◽  
Luc S Djogbenou ◽  
Aubin A Koumba ◽  
Laurette Djossou ◽  
Athanase Badolo ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Resistance Mechanisms ◽  
Malaria Vectors ◽  
Effective Control ◽  
Anopheles Coluzzii ◽  
Anopheles Gambiae S.S ◽  
Diagnostic Dose ◽  
Pirimiphos Methyl ◽  
Old Adult

Abstract An effective control of malaria vectors requires an extensive knowledge of mechanisms underlying the resistance-phenotypes developed by these vectors against insecticides. We investigated Anopheles gambiae mosquitoes from Benin and Togo for their intensity of insecticide resistance and we discussed the involvement of genotyped mechanisms in the resistance-phenotypes observed. Three- to five-day-old adult mosquitoes emerged from field and laboratory An. gambiae larvae were assayed using WHO tube intensity tests against various doses of deltamethrin: 1× (0.05%); 2× (0.1%); 5× (0.25%); 7.5× (0.375%) and those of pirimiphos-methyl: 0.5× (0.125%); 1× (0.25%). Members of An. gambiae complex were screened in field populations using polymerase chain reaction (PCR) assays. The presence of kdrR(1014F/1014S) and ace-1R(119S) mutations was also investigated using TaqMan and PCR-RFLP techniques, respectively. Anopheles gambiae from field were very resistant to deltamethrin, whereas KisKdr and AcerKdrKis strains displayed 100% mortality rates at 2× the diagnostic dose. In contrast, the field mosquitoes displayed a low resistance-intensity against 1× the diagnostic dose of pirimiphos-methyl, whereas AcerKis and AcerKdrKis strains showed susceptibility at 0.5× the diagnostic dose. Anopheles gambiae s.s., Anopheles coluzzii, and Anopheles arabiensis were identified. Allelic frequencies of kdrR (1014F) and ace-1R (119S) mutations in the field populations varied from 0.65 to 1 and 0 to 0.84, respectively. The field An. gambiae displayed high-resistance levels against deltamethrin and pirimiphos-methyl when compared with those of the laboratory An. gambiae-resistant strains. These results exhibit the complexity of underlying insecticide resistance mechanisms in these field malaria vectors.

Insecticide susceptibility status in individual species of the Anopheles gambiae complex (Diptera: Culicidae) in an area of The Gambia where pyrethroid impregnated bednets are used extensively for malaria control

1995 ◽  
Vol 85 (2) ◽  
pp. 229-234 ◽  
Author(s):  
J. Hemingway ◽  
S.W. Lindsay ◽  
G.J. Small ◽  
M. Jawara ◽  
F.H. Collins
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Malaria Control ◽  
The Gambia ◽  
Malaria Vectors ◽  
Cross Resistance ◽  
Individual Species ◽  
Sentinel Site ◽  
Malaria Control Programme ◽  
Biochemical Assays

AbstractPyrethroid-impregnated bednets are being used nationwide in The Gambia. The future success of this malaria control programme depends partly on the vectors remaining susceptible to those insecticides used for treating the nets. The present study was carried out on the south bank of the river Gambia, during the first large scale trial of nets in this country. Thus this area represents a sentinel site for detecting insecticide resistance in local vectors. This study gives an example of how a system of early detection for resistance problems can be set up in a relatively complex situation where multiple vectors and non-vectors are present. Samples of the Anopheles gambiae complex were caught indoors using light traps in twelve villages used in the bednet study. In all villages A. gambiae sensu stricto Giles was the predominant member of the complex as determined using the rDNA-PCR diagnostic assay. Limited bioassays with DDT and permethrin, and biochemical assays for a range of insecticide resistance mechanisms suggest that the A. gambiae complex remains completely susceptible to all major classes of commonly used insecticides including pyrethroids. Biochemical assays suggest that a low frequency of DDT resistance may occur in A. melas Theobald. This is based on elevated glutathione S-transferase levels coupled with increased levels of DDT metabolism and does not involve cross-resistance to pyrethroids. Therefore we do not envisage a decline in the efficacy of treated nets against malaria vectors in the study area in the immediate future, although monitoring should be continued whilst wide-scale use of impregnated bednets is operational.

scholarly journals Functional genetic validation of key genes conferring insecticide resistance in the major African malaria vector, Anopheles gambiae

2019 ◽  
Author(s):  
Adriana Adolfi ◽  
Beth Poulton ◽  
Amalia Anthousi ◽  
Stephanie Macilwee ◽  
Hilary Ranson ◽  
...  
Keyword(s):  
Public Health ◽  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Pyrethroid Resistance ◽  
Control Strategies ◽  
Resistance Mechanisms ◽  
Effective Control ◽  
Cross Resistance ◽  
Toxic Metabolite ◽  
Control Programs

ABSTRACTResistance in Anopheles gambiae to members of all four major classes (pyrethroids, carbamates, organochlorines and organophosphates) of public health insecticides limits effective control of malaria transmission in Africa. Increased expression of detoxifying enzymes has been associated with resistance, but direct functional validation in An. gambiae has been lacking. Here we perform transgenic analysis using the GAL4/UAS system to examine insecticide resistance phenotypes conferred by increased expression of the three genes - Cyp6m2, Cyp6p3 and Gste2 - most often found upregulated in resistant An. gambiae. We report the first evidence in An. gambiae that organophosphate and organochlorine resistance is conferred by overexpression of GSTE2 in a broad tissue profile. Pyrethroid and carbamate resistance is bestowed by similar Cyp6p3 overexpression, and Cyp6m2 confers only pyrethroid resistance when overexpressed in the same tissues. Conversely, such Cyp6m2 overexpression increases susceptibility to the organophosphate malathion, presumably due to conversion to a more toxic metabolite. No resistant phenotypes are conferred when either Cyp6 gene overexpression is restricted to the midgut or oenocytes, answering long standing questions related to the importance of these tissues in resistance to contact insecticides. Validation of genes conferring resistance provides markers to guide control strategies, and the observed negative cross-resistance due to Cyp6m2 gives credence to proposed dual insecticide strategies to overcome pyrethroid resistance. These trasnsgenic An. gambiae resistant lines are being used to test potential liabilities in new active compounds early in development.SIGNIFICANCE STATEMENTInsecticide resistance in Anopheles gambiae mosquitoes can derail malaria control programs, and to overcome it we need to discover the underlying molecular basis. Here, for the first time, we characterise three genes most often associated with insecticide resistance directly by their overproduction in genetically modified An. gambiae. We show that overexpression of each gene confers resistance to representatives of at least one insecticide class and, taken together, the three genes provide cross-resistance to all four major insecticide classes currently used in public health. These data validate the candidate genes as markers to monitor the spread of resistance in mosquito populations. The modified mosquitoes produced are also valuable tools to pre-screen new insecticides for potential liabilities to existing resistance mechanisms.

scholarly journals Malaria Transmission, Vector Diversity, and Insecticide Resistance at a Peri-Urban Site in the Forest Zone of Ghana

2021 ◽  
Vol 2 ◽  
Author(s):  
Yaw Akuamoah-Boateng ◽  
Ruth C. Brenyah ◽  
Sandra A. Kwarteng ◽  
Patrick Obuam ◽  
Isaac Owusu-Frimpong ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Malaria Transmission ◽  
Urban Setting ◽  
World Health ◽  
Malaria Vectors ◽  
Urban Site ◽  
Human Landing Catch ◽  
Anopheles Coluzzii ◽  
Anopheles Gambiae S.S

IntroductionRecent surge of Anopheles resistance to major classes of World Health Organization (WHO)-approved insecticides globally necessitates the need for information about local malaria vector populations. It is believed that insecticide efficacy loss may lead to operational failure of control interventions and an increase in malaria infection transmission. We investigated the susceptibility levels of malaria vectors to all classes of WHO-approved vector control insecticides and described the dynamics of malaria transmission in a peri-urban setting.MethodsFit 3–5-day-old adults that emerged from Anopheles larvae collected from several different sites in the study area were subjected to the WHO bioassay for detecting insecticide resistance. The knockdown resistance gene (kdr) mutations within the vector populations were detected using PCR. Entomological inoculation rates were determined using the human landing catch technique and Plasmodium falciparum circumsporozoite ELISA.ResultsThe malaria vectors from the study area were resistant to all classes of insecticides tested. Out of the 284 Anopheles complex specimen assayed for the resistance study, 265 (93.30%) were identified as Anopheles gambiae s.s. The kdr gene was detected in 90% of the Anopheles gambiae s.s. assayed. In an area where Anopheles coluzzii resistance to insecticides had never been reported, the kdr gene was detected in 78% of the Anopheles coluzzii sampled. The entomological inoculation rate (EIR) for the dry season was 1.44 ib/m/n, whereas the EIR for the rainy season was 2.69 ib/m/n.ConclusionsThis study provides information on the high parasite inoculation rate and insecticide resistance of malaria vectors in a peri-urban community, which is critical in the development of an insecticide resistance management program for the community.

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

2019 ◽  
Author(s):  
Caleb Stica ◽  
Claire L. Jeffries ◽  
Seth R. Irish ◽  
Yaya Barry ◽  
Denka Camara ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Scale Up ◽  
Indoor Residual Spraying ◽  
Control Program ◽  
Sub Saharan Africa ◽  
Health Concern ◽  
Global Public Health ◽  
Metabolic Resistance

AbstractBackgroundIn recent years, the scale-up of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) has greatly reduced malaria transmission. However, malaria remains a global public health concern with the majority of disease burden in sub-Saharan Africa. Insecticide resistance is a growing problem among Anopheles vector populations, with potential implications for the continued effectiveness of available control interventions. Improved understanding of current resistance levels and underlying mechanisms is essential to design appropriate management strategies and to mitigate future selection for resistance.MethodsAnopheles gambiae s.l. mosquitoes were collected from three villages in Faranah Prefecture, Guinea and their levels of susceptibility to seven insecticides were measured using CDC resistance intensity bioassays. Synergist assays with piperonyl butoxide (PBO) were also undertaken to assess the role of elevated mixed-function oxidases in resistance. RNA was extracted from 563 individuals and PCR was performed on cDNA to determine vector species, presence of target site mutations (L1014F kdr, N1575Y and G119S Ace-1), Plasmodium falciparum infection, and relative expression of three metabolic genes (CYP6M2, CYP6P3 and GSTD3).ResultsIn Faranah, resistance to permethrin and deltamethrin was observed, as well as possible resistance to bendiocarb. All assayed vector populations were fully susceptible to alpha-cypermethrin, pirimiphos-methyl, clothianidin and chlorfenapyr. Plasmodium falciparum infection was detected in 7.3% (37/508) mosquitoes tested. The L1014F kdr mutation was found in 100% of a sub-sample of 60 mosquitoes, supporting its fixation in the region. The N1575Y mutation was identified in 20% (113/561) of individuals, with ongoing selection evidenced by significant deviations from Hardy-Weinberg equilibrium. The G119S Ace-1 mutation was detected in 62.1% (18/29) of mosquitoes tested and was highly predictive of bendiocarb bioassay survival. The metabolic resistance genes, CYP6M2, CYP6P3 and GSTD3, were found to be overexpressed in wild resistant and susceptible An. gambiae s.s. populations, compared to a susceptible G3 colony. Furthermore, CYP6P3 was significantly overexpressed in bendiocarb survivors, implicating its potential role in carbamate resistance in Faranah.ConclusionsIdentification of intense resistance to permethrin and deltamethrin in Faranah, is of concern, as the Guinea National Malaria Control Program (NMCP) relies exclusively on the distribution of pyrethroid-treated LLINs for vector control. Study findings will be used to guide current and future control strategies in the region.

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