scholarly journals Hétérogénéité génétique et résistance des vecteurs du paludisme (Anopheles gambiae s.l) aux insecticides en zone cotonnière au Benin

2020 ◽  
Vol 14 (8) ◽  
pp. 2724-2736
Author(s):  
Rock Aikpon ◽  
Antoine Missihoun ◽  
Antoine Lokossou ◽  
Gorgias Aikpon ◽  
Sahidou Salifou ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
Genetic Resistance ◽  
Malaria Vectors ◽  
Human Landing Catch ◽  
Anopheles Coluzzii ◽  
Resistance Allele ◽  
Two Samples ◽  
Mosquito Collection ◽  
Anopheles Gambiae S.L ◽  
Mutation Kdr

La résistance des vecteurs du paludisme aux insecticides utilisés dans la lutte anti vectorielle est un obstacle majeur pour les programmes nationaux de lutte contre le paludisme. La présente étude avait pour but d’évaluer la diversité génétique des populations de Anopheles gambiae et la résistance aux insecticides (mutation Kdr et Ace-1) en zone cotonnière au Bénin. Deux méthodes de capture ont été utilisées pour la collecte d’échantillon. La capture sur appât humain et la récolte de la faune résiduelle matinale par spray. La PCR SINE a permis de distinguer deux espèces jumelles et d’obtenir les différents génotypes pour les deux gènes. Deux espèces du complexe An. gambiae s.l ont été trouvées en sympatrie (Anopheles coluzzii et Anopheles gambiae). La résistance kdr et Ace-1 connaissent un flux saisonnier. L’allèle résistant du gène kdr est fixé dans la population de vecteurs (Fis>0). Par contre, un déficit de l’allèle résistant est noté au niveau du gène Ace-1 (Fis<0).Mots clés : Hétérogénéité, génétique, résistance, vecteur, paludisme. English Title: Genetic heterogeneity and resistance to insecticides in malaria vector Anopheles gambiae s.l in the cotton growing area in Benin Resistance of malaria vectors to insecticides used in vector control is a major threat for national malaria control programs. The purpose of this study was to assess the genetic diversity of Anopheles gambiae populations and resistance to insecticides (Kdr Ace-1 mutation) in the cotton growing area in Benin. Two samples methods were used for mosquito collection: Human Landing catch (HLC) and the residual fauna collection by spray. The SINE PCR allow to identify species the different genotypes resistance genes. Two species of the An. gambiae s.l complex have been found in sympatry (Anopheles coluzzii and Anopheles gambiae). kdr and Ace-1 resistance had seasonal variation trend. The kdr resistance allele is fixed in the vector population (Fis> 0). Moreover, a deficit of the Ace-1 resistance allele was observed (Fis <0). Keywords: Heterogeneity, genetic, resistance, vector, malaria.

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 The genetic architecture of target-site resistance to pyrethroid insecticides in the African malaria vectors Anopheles gambiae and Anopheles coluzzii

2018 ◽  
Author(s):  
Chris S. Clarkson ◽  
Alistair Miles ◽  
Nicholas J. Harding ◽  
David Weetman ◽  
Dominic Kwiatkowski ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Positive Selection ◽  
Anopheles Gambiae ◽  
Pyrethroid Resistance ◽  
Target Site ◽  
Malaria Vectors ◽  
Anopheles Coluzzii ◽  
Resistance Allele ◽  
Pyrethroid Insecticides ◽  
Recent Positive Selection

AbstractResistance to pyrethroid insecticides is a major concern for malaria vector control, because these are the compounds used in almost all insecticide-treated bed-nets (ITNs), and are also widely used for indoor residual spraying (IRS). Pyrethroids target the voltage-gated sodium channel (VGSC), an essential component of the mosquito nervous system, but substitutions in the amino acid sequence can disrupt the activity of these insecticides, inducing a resistance phenotype. Here we use Illumina whole-genome sequence data from phase 1 of the Anopheles gambiae 1000 Genomes Project (Ag1000G) to provide a comprehensive account of genetic variation in the Vgsc gene in mosquito populations from eight African countries. In addition to the three known resistance alleles, we describe 20 non-synonymous nucleotide substitutions at appreciable frequency in one or more populations that are previously unknown in Anopheles mosquitoes. Thirteen of these novel alleles were found to occur almost exclusively on haplotypes carrying the known L995F resistance allele (L1014F in Musca domesticus codon numbering), and may enhance or compensate for the L995F resistance pheno-type. A novel mutation I1527T, which is adjacent to a predicted pyrethroid binding site, was found in tight linkage with either of two alleles causing a V402L substitution, similar to a combination of substitutions found to cause pyrethroid resistance in several other insect species. We analyse the genetic backgrounds on which non-synonymous alleles are found, to determine which alleles have experienced recent positive selection, and to refine our understanding of the spread of resistance between species and geographical locations. We describe twelve distinct haplotype groups with evidence of recent positive selection, five of which carry the known L995F resistance allele, five of which carry the known L995S resistance allele, one of which carries the novel I1527T allele, and one of which carries a novel M490I allele. Seven of these groups are localised to a single geographical location, and five comprise haplotypes from different countries, in one case separated by over 3000 km, providing new information about the geographical distribution and spread of resistance. We also find evidence for multiple introgression events transmitting resistance alleles between An. gambiae and An. coluzzii. We identify markers that could be used to design high-throughput, low-cost genetic assays for improved surveillance of pyrethroid resistance in the field. Our results demonstrate that the molecular basis of target-site pyrethroid resistance in malaria vectors is more complex than previously appreciated, and provide a foundation for the development of new genetic tools to track the spread insecticide resistance and improve the design of strategies for insecticide resistance management.

scholarly journals Anopheles gambiae Genome Conservation as a Resource for Rational Gene Drive Target Site Selection

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 97
Author(s):  
Nace Kranjc ◽  
Andrea Crisanti ◽  
Tony Nolan ◽  
Federica Bernardini
Keyword(s):  
Anopheles Gambiae ◽  
Data Storage ◽  
Genomic Variation ◽  
Malaria Vectors ◽  
Anopheles Coluzzii ◽  
Structural Constraints ◽  
Gene Drive ◽  
Genetic Traits ◽  
A Genome ◽  
Insight Into

The increase in molecular tools for the genetic engineering of insect pests and disease vectors, such as Anopheles mosquitoes that transmit malaria, has led to an unprecedented investigation of the genomic landscape of these organisms. The understanding of genome variability in wild mosquito populations is of primary importance for vector control strategies. This is particularly the case for gene drive systems, which look to introduce genetic traits into a population by targeting specific genomic regions. Gene drive targets with functional or structural constraints are highly desirable as they are less likely to tolerate mutations that prevent targeting by the gene drive and consequent failure of the technology. In this study we describe a bioinformatic pipeline that allows the analysis of whole genome data for the identification of highly conserved regions that can point at potential functional or structural constraints. The analysis was conducted across the genomes of 22 insect species separated by more than hundred million years of evolution and includes the observed genomic variation within field caught samples of Anopheles gambiae and Anopheles coluzzii, the two most dominant malaria vectors. This study offers insight into the level of conservation at a genome-wide scale as well as at per base-pair resolution. The results of this analysis are gathered in a data storage system that allows for flexible extraction and bioinformatic manipulation. Furthermore, it represents a valuable resource that could provide insight into population structure and dynamics of the species in the complex and benefit the development and implementation of genetic strategies to tackle malaria.

scholarly journals Effect of naturally occurring Wolbachia in Anopheles gambiae s.l. mosquitoes from Mali on Plasmodium falciparum malaria transmission

2017 ◽  
Vol 114 (47) ◽  
pp. 12566-12571 ◽  
Author(s):  
Fabio M. Gomes ◽  
Bretta L. Hixson ◽  
Miles D. W. Tyner ◽  
Jose Luis Ramirez ◽  
Gaspar E. Canepa ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Anopheles Gambiae ◽  
Malaria Transmission ◽  
Deleterious Effect ◽  
Plasmodium Falciparum Malaria ◽  
Anopheles Coluzzii ◽  
Naturally Occurring ◽  
Anopheles Gambiae S.L ◽  
Cat Fleas ◽  
Sporozoite Infection

A naturally occurring Wolbachia strain (wAnga-Mali) was identified in mosquitoes of the Anopheles gambiae complex collected in the Malian villages of Dangassa and Kenieroba. Phylogenetic analysis of the nucleotide sequence of two 16S rRNA regions showed that wAnga-Mali clusters with Wolbachia strains from supergroup A and has the highest homology to a Wolbachia strain isolated from cat fleas (Ctenocephalides). wAnga-Mali is different from two Wolbachia strains previously reported in A. gambiae from Burkina Faso (wAnga_VK5_STP and wAnga_VK5_3.1a). Quantitative analysis of Wolbachia and Plasmodium sporozoite infection in field-collected mosquitoes indicates that the prevalence and intensity of Plasmodium falciparum sporozoite infection is significantly lower in Wolbachia-infected females. The presence of Wolbachia in females from a laboratory Anopheles coluzzii (A. gambiae, M form) colony experimentally infected with P. falciparum (NF54 strain) gametocyte cultures slightly enhanced oocyst infection. However, Wolbachia infection significantly reduced the prevalence and intensity of sporozoite infection, as observed in the field. This indicates that wAnga-Mali infection does not limit early stages of Plasmodium infection in the mosquito, but it has a strong deleterious effect on sporozoites and reduces malaria transmission.

scholarly journals Pyrethroid and Etofenprox Resistance in Anopheles gambiae and Anopheles coluzzii from Vegetable Farms in Yaoundé, Cameroon: Dynamics, Intensity and Molecular Basis

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5543
Author(s):  
Michael Piameu ◽  
Philippe Nwane ◽  
Wilson Toussile ◽  
Konstantinos Mavridis ◽  
Nadja Christina Wipf ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
Mortality Rates ◽  
World Health ◽  
Anopheles Coluzzii ◽  
Cross Sectional ◽  
Metabolic Genes ◽  
Anopheles Gambiae S.L ◽  
Underlying Mechanisms ◽  
Health Organization ◽  
The City

Previous studies have indicated widespread insecticide resistance in malaria vector populations from Cameroon. However, the intensity of this resistance and underlying mechanisms are poorly known. Therefore, we conducted three cross-sectional resistance surveys between April 2018 and October 2019, using the revised World Health Organization protocol, which includes resistance incidences and intensity assessments. Field-collected Anopheles gambiae s.l. populations from Nkolondom, Nkolbisson and Ekié vegetable farms in the city of Yaoundé were tested with deltamethrin, permethrin, alpha-cypermethrin and etofenprox, using 1× insecticide diagnostic concentrations for resistance incidence, then 5× and 10× concentrations for resistance intensity. Subsamples were analyzed for species identification and the detection of resistance-associated molecular markers using TaqMan® qPCR assays. In Nkolbisson, both An. coluzzii (96%) and An. gambiae s.s. (4%) were found together, whereas only An. gambiae s.s. was present in Nkolondom, and only An. coluzzii was present in Ekié. All three populations were resistant to the four insecticides (<75% mortality rates―MR1×), with intensity generally fluctuating over the time between mod-erate (<98%―MR5×; ≥98%―MR10×) and high (76–97%―MR10×). The kdr L995F, L995S, and N1570Y, and the Ace-1 G280S-resistant alleles were found in An. gambiae from Nkolondom, at 73%, 1%, 16% and 13% frequencies, respectively, whereas only the kdr L995F was found in An. gambiae s.s. from Nkolbisson at a 50% frequency. In An. coluzzii from Nkolbisson and Ekié, we detected only the kdr L995F allele at 65% and 60% frequencies, respectively. Furthermore, expression levels of Cyp6m2, Cyp9k1, and Gste2 metabolic genes were highly upregulated (over fivefold) in Nkolondom and Nkolbisson. Pyrethroid and etofenprox-based vector control interventions may be jeopardized in the prospected areas, due to high resistance intensity, with multiple mechanisms in An. gambiae s.s. and An. coluzzii.

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.

scholarly journals Rapid high throughput SYBR green assay for identifying the malaria vectors Anopheles arabiensis, Anopheles coluzzii and Anopheles gambiae s.s. Giles

PLoS ONE ◽  
2019 ◽  
Vol 14 (4) ◽  
pp. e0215669 ◽  
Author(s):  
Joseph Chabi ◽  
Arjen Van’t Hof ◽  
Louis K. N’dri ◽  
Alex Datsomor ◽  
Dora Okyere ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
High Throughput ◽  
Anopheles Arabiensis ◽  
Sybr Green ◽  
Malaria Vectors ◽  
Anopheles Coluzzii ◽  
Anopheles Gambiae S.S ◽  
Sybr Green Assay

scholarly journals Contrasting effects of the alkaloid ricinine on the capacity of Anopheles gambiae s.l. to transmit Plasmodium falciparum

2021 ◽  
Author(s):  
Domonbabele François de Sales Hien ◽  
Prisca S. L. Paré ◽  
Amanda Cooper ◽  
Benjamin K. Koama ◽  
Edwige Guissou ◽  
...  
Keyword(s):  
Growth Rate ◽  
Plasmodium Falciparum ◽  
Anopheles Gambiae ◽  
Ricinus Communis ◽  
Control Agent ◽  
Phenotypic Traits ◽  
Anopheles Coluzzii ◽  
Vector Borne Diseases ◽  
Anopheles Gambiae S.L ◽  
The Impact

Abstract Background: Besides feeding on blood, females of the malaria vector Anopheles gambiae s.l. readily feed on natural sources of plant sugars. The impact of toxic secondary phytochemicals contained in plant-derived sugars on mosquito physiology and on the development of Plasmodium parasites remains elusive. The focus of this study was to explore the influence of the alkaloid ricinine, found in the nectar of the castorbean Ricinus communis, on the mosquito ability to transmit Plasmodium falciparum. Methods: Females of Anopheles gambiae and its sibling species Anopheles coluzzii were exposed to ricinine through sugar feeding assays to assess the effect of this phytochemical on mosquito survival, the level of P. falciparum infection, and the growth rate of the parasite. Results: Ricinine induced a significant reduction in the longevity of both Anopheles species. Ricinine caused acceleration in the parasite growth rate with an earlier invasion of the salivary glands in both species. At a concentration of 0.04 g l-1 in An. coluzzii, ricinine had no effect on mosquito infection, while 0.08 g l-1 ricinine-5% glucose solution induced a 14% increase in An. gambiae infection rate. Conclusions: Overall, our findings reveal that consumption of certain nectar phytochemicals can have unsuspected and contrasting effects on key phenotypic traits that govern the intensity of malaria transmission. Further studies will be required before concluding on the putative role of ricinine as a novel control agent, including the development of ricinine-based toxic and transmission-blocking sugar baits. Testing other secondary phytochemicals in plant nectar will provide a broader understanding of the impact, which plants can have on the transmission of vector-borne diseases.

scholarly journals The G119S Acetylcholinesterase (Ace-1) Target Site Mutation Confers Carbamate Resistance in the Major Malaria Vector Anopheles gambiae from Cameroon: A Challenge for the Coming IRS Implementation

2019 ◽  
Author(s):  
Emmanuel Elanga-Ndille ◽  
Lynda Nouage ◽  
Cyrille Ndo ◽  
Achille Binyang ◽  
Tatiane Assatse ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
Phylogenetic Analyses ◽  
Central Africa ◽  
Malaria Vectors ◽  
Resistance Allele ◽  
Site Mutation ◽  
The West ◽  
Carbamate Insecticides ◽  
Southern Cameroon ◽  
Major Malaria Vector

Growing resistance is reported to carbamate insecticides in malaria vectors in Cameroon. However, the contribution of acetylcholinesterase (Ace-1) to this resistance remains uncharacterised. Here, we established that the Ace-1R mutation is driving resistance to carbamates in Anopheles gambiae populations from Cameroon. Insecticide bioassay on field collected mosquitoes from Bankeng, a locality in southern Cameroon, showed high resistance to the carbamates bendiocarb (64.8 &plusmn; 3.5 % mortality) and propoxur (55.71 &plusmn; 2.9 %) but a full susceptibility to the organophosphate fenithrothion. The TaqMan genotyping of the Ace-1R mutation with field-collected adults revealed the presence of this resistance allele (39%). A significant correlation was observed between the Ace-1R and carbamate resistance at allelic [(bendiocarb; OR = 75.9; P&lt;0.0001) and (propoxur; OR= 1514; P&lt;0.0001)] and genotypic [RR vs SS (bendiocarb; OR = 120.8; P&lt;0.0001) and (propoxur; OR= 3277; P&lt;0.0001) levels. Furthermore, the presence of the mutation was confirmed by sequencing an Ace-1 portion flanking codon 119. The cloning of this fragment revealed a likely duplication of Ace-1 in Cameroon as mosquitoes exhibited at least three distinct haplotypes. Phylogenetic analyses showed that the predominant Ace-1R allele is identical to that from West Africa suggesting a recent introduction of this allele in Central Africa from the West. The spread of this Ace-1R represents a serious challenge to future implementation of IRS-based interventions using carbamates or organophosphates in Cameroon.

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