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 Evolution of the Pyrethroids Target-Site Resistance Mechanisms in Senegal: Early Stage of the Vgsc-1014F and Vgsc-1014S Allelic Frequencies Shift

Genes ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1948
Author(s):  
Moussa Diallo ◽  
Majidah Hamid-Adiamoh ◽  
Ousmane Sy ◽  
Pape Cheikh Sarr ◽  
Jarra Manneh ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Pyrethroid Resistance ◽  
Early Stage ◽  
Resistance Mechanisms ◽  
Sub Saharan Africa ◽  
Malaria Vectors ◽  
Malaria Control Programme ◽  
Anopheles Coluzzii ◽  
Resistance Mutations

The evolution and spread of insecticide resistance mechanisms amongst malaria vectors across the sub-Saharan Africa threaten the effectiveness and sustainability of current insecticide-based vector control interventions. However, a successful insecticide resistance management plan relies strongly on evidence of historical and contemporary mechanisms circulating. This study aims to retrospectively determine the evolution and spread of pyrethroid resistance mechanisms among natural Anopheles gambiae s.l. populations in Senegal. Samples were randomly drawn from an existing mosquito sample, collected in 2013, 2017, and 2018 from 10 sentinel sites monitored by the Senegalese National Malaria Control Programme (NMCP). Molecular species of An. gambiae s.l. and the resistance mutations at the Voltage-gated Sodium Channel 1014 (Vgsc-1014) locus were characterised using PCR-based assays. The genetic diversity of the Vgsc gene was further analyzed by sequencing. The overall species composition revealed the predominance of Anopheles arabiensis (73.08%) followed by An. gambiae s.s. (14.48%), Anopheles coluzzii (10.94%) and Anopheles gambiae–coluzii hybrids (1.48%). Both Vgsc-1014F and Vgsc-1014S mutations were found in all studied populations with a spatial variation of allele frequencies from 3% to 90%; and 7% to 41%, respectively. The two mutations have been detected since 2013 across all the selected health districts, with Vgsc-L1014S frequency increasing over the years while Vgsc-1014F decreasing. At species level, the Vgsc-1014F and Vgsc-1014S alleles were more frequent amongst An. gambiae s.s. (70%) and An. arabiensis (20%). The Vgsc gene was found to be highly diversified with eight different haplotypes shared between Vgsc-1014F and Vgsc-1014S. The observed co-occurrence of Vgsc-1014F and Vgsc-1014S mutations suggest that pyrethroid resistance is becoming a widespread phenomenon amongst malaria vector populations, and the NMCP needs to address this issue to sustain the gain made in controlling malaria.

scholarly journals Insecticide resistance status of malaria vectors Anopheles gambiae (s.l.) of southwest Burkina Faso and residual efficacy of indoor residual spraying with microencapsulated pirimiphos-methyl insecticide

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Dieudonné Diloma Soma ◽  
Barnabas Zogo ◽  
Domonbabele François de Sales Hien ◽  
Aristide Sawdetuo Hien ◽  
Didier Alexandre Kaboré ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Burkina Faso ◽  
Anopheles Gambiae ◽  
Local Population ◽  
Residual Activity ◽  
Indoor Residual Spraying ◽  
Susceptible Strain ◽  
Malaria Vectors ◽  
Pirimiphos Methyl ◽  
Residual Efficacy

Abstract Background The rapid spread of insecticide resistance in malaria vectors and the rebound in malaria cases observed recently in some endemic areas underscore the urgent need to evaluate and deploy new effective control interventions. A randomized control trial (RCT) was conducted with the aim to investigate the benefit of deploying complementary strategies, including indoor residual spraying (IRS) with pirimiphos-methyl in addition to long-lasting insecticidal nets (LLINs) in Diébougou, southwest Burkina Faso. Methods We measured the susceptibility of the Anopheles gambiae (s.l.) population from Diébougou to conventional insecticides. We further monitored the efficacy and residual activity of pirimiphos-methyl on both cement and mud walls using a laboratory susceptible strain (Kisumu) and the local An. gambiae (s.l.) population. Results An. gambiae (s.l.) from Diébougou was resistant to DDT, pyrethroids (deltamethrin, permethrin and alphacypermethrin) and bendiocarb but showed susceptibility to organophosphates (pirimiphos-methyl and chlorpyrimiphos-methyl). A mixed-effect generalized linear model predicted that pirimiphos-methyl applied on cement or mud walls was effective for 210 days against the laboratory susceptible strain and 247 days against the local population. The residual efficacy of pirimiphos-methyl against the local population on walls made of mud was similar to that of cement (OR = 0.792, [0.55–1.12], Tukey’s test p-value = 0.19). Conclusions If data on malaria transmission and malaria cases (as measured trough the RCT) are consistent with data on residual activity of pirimiphos-methyl regardless of the type of wall, one round of IRS with pirimiphos-methyl would have the potential to control malaria in a context of multi-resistant An. gambiae (s.l.) for at least 7 months.

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.

Building multi‐layered resilience in a malaria control programme in Dar es Salaam, Tanzania

2010 ◽  
Vol 10 (4) ◽  
pp. 309-324 ◽  
Author(s):  
Stefan Dongus ◽  
Constanze Pfeiffer ◽  
Emmy Metta ◽  
Selemani Mbuyita ◽  
Brigit Obrist
Keyword(s):  
Malaria Control ◽  
Breeding Site ◽  
Control Programme ◽  
Malaria Vectors ◽  
Malaria Control Programme ◽  
Social Resilience ◽  
Breeding Sites ◽  
Mosquito Breeding ◽  
Field Workers ◽  
Local Leaders

This study applied the multi‐layered social resilience framework in the context of an urban malaria control programme by using a qualitative approach. It was found that exchange between and within administrative levels supported resilience‐building processes in terms of mosquito breeding site elimination. ‘Reactive’ and ‘proactive’ capacities were successfully built among programme staff. However, more potential could be tapped among local leaders and household members, by increasing their competence in eliminating breeding sites of malaria vectors. Improving the communication skills of the programme’s field workers might support such processes. Together with local leaders, they could act as multipliers of sensitisation messages.

scholarly journals Cuticular hydrocarbons are associated with mating success and insecticide resistance in malaria vectors

2021 ◽  
Author(s):  
Kelsey L Adams ◽  
Simon P Sawadogo ◽  
Charles Nignan ◽  
Abdoulaye Niang ◽  
Douglas G Paton ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Cuticular Hydrocarbons ◽  
Malaria Control ◽  
Mating Success ◽  
Malaria Vectors ◽  
Male Mating ◽  
Anopheles Coluzzii ◽  
Female Ratio ◽  
Selection For ◽  
Male To Female

Anopheles coluzzii females, important malaria vectors in Africa, mate only once in their lifetime. Mating occurs in aerial swarms with a high male-to-female ratio, where the traits underling male mating success are largely unknown. Here, we investigated whether cuticular hydrocarbons (CHCs) influence mating success in natural mating swarms in Burkina Faso. As insecticides are widely used in this area for malaria control, we also determined whether CHCs affect insecticide resistance levels. We find that mated males have higher CHC abundance than unmated controls, suggesting CHCs could be a determinant of mating success. Additionally, mated males have higher insecticide resistance under pyrethroid challenge, and we show a link between resistance intensity and CHC abundance. Taken together, our results reveal overlapping roles played by CHCs in mate choice and insecticide resistance, and point to sexual selection for insecticide resistance traits that limit the efficacy of our best malaria control tools.

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.

Morphological and molecular characterization of endophilic Anopheles gambiae complex, in Itu Local Government Area, Akwa Ibom State, Nigeria

2020 ◽  
Vol 41 (1) ◽  
pp. 75-81
Author(s):  
B.E. Bassey ◽  
K.N. Opara ◽  
L.P. Usip
Keyword(s):  
Local Government ◽  
Anopheles Gambiae ◽  
Molecular Characterization ◽  
Malaria Control ◽  
Local Government Area ◽  
Malaria Control Programme ◽  
Anopheles Species ◽  
Gambiae Complex ◽  
Anopheles Mosquitoes ◽  
Significant Difference

Malaria is still regarded as a major public health problem in sub-Saharan African countries. Anopheles mosquitoes have been implicated as the major malaria vectors. However, species abundance, composition and distribution vary between different ecological zones. This study investigated the composition and distribution of Anopheles gambiae mosquitoes in Itu Local Government Area, Akwa Ibom State, Nigeria. Adult Anopheles mosquitoes were sampled bi-weekly from 15 randomly selected houses each from three communities in the study area by pyrethroid spray capture (PSC) method. Adult Anopheles species were identified morphologically and sibling species were further subjected to species- specific polymerase chain reaction (PCR) typing. A total of 269 female Anopheles species were caught between July and December, 2015. The study indicated significant (p<0.05) abundance of Anopheles gambiae siblings, with An. gambiae s.s recording 219(81.41%) followed by An. arabiensis 32(11.90%). A proportion of the samples were unidentified 18(6.69%). There was a significant difference (p<0.05) in the distribution of A. gambiae complex over the period of the study with a peak in September 89(33.01%). Anopheles mosquitoes were more abundant in Itu Oma 120(44.66%) than West Itam 98(36.43%) and East Itam 51(18.96%). The study also recorded significantly (p<0.05) higher rate of blood engorged female Anopheles (54.05%). This finding showed that An. gambiae s.s was the predominant malaria vector in the area and also, the incidence of malaria been likely to increase during the wet season. Therefore, vector control must be carried out in these communities to reduce the number of these indoor biting mosquitoes. This study therefore, will be useful as baseline data to help design strategies for malaria control in Itu Local Government Area and also facilitate the success of the ongoing effort on the malaria control programme in the State. Keywords: Malaria; Anopheles, morphological; molecular; characterization; Akwa Ibom; Nigeria.

High Levels of Knockdown Resistance in Anopheles coluzzii and Anopheles gambiae (Diptera: Culicidae), Major Malaria Vectors in Togo, West Africa: A 2011 Monitoring Report

2019 ◽  
Vol 56 (4) ◽  
pp. 1159-1164
Author(s):  
Koffi Mensah Ahadji-Dabla ◽  
Adjovi Djifa Amoudji ◽  
Seth Wolali Nyamador ◽  
Georges Yawo Apétogbo ◽  
Joseph Chabi ◽  
...  
Keyword(s):  
West Africa ◽  
Anopheles Gambiae ◽  
National Malaria Control Programme ◽  
Control Programme ◽  
World Health ◽  
Malaria Vectors ◽  
Malaria Control Programme ◽  
Anopheles Coluzzii ◽  
Knockdown Resistance ◽  
Anopheles Gambiae S.S

Abstract A survey of susceptibility to DDT, deltamethrin, bendiocarb, and chlorpyrifos-methyl was conducted in five localities in 2011 in Togo, West Africa, to assess the insecticide resistance status of Anopheles gambiae s.l. (Diptera: Culicidae). Female populations of An. gambaie s.l. emerged from collected larvae (F0) were exposed to insecticide-impregnated papers using World Health Organization test kits for adult mosquitoes; the susceptible reference strain Kisumu was used as a control. Resistance to DDT and deltamethrin was observed within the mosquito populations tested. Anopheles gambiae s.s. and Anopheles coluzzii represented the only species recorded in the study sites. The frequency of knockdown resistance (kdr L1014F) mutation determined using polymerase chain reaction diagnostic tests was lower in An. gambiae than in An. coluzzii in all of the localities except Kolokopé. Further investigations of An. gambiae s.l. resistance are needed in Togo to help the National Malaria Control Programme in vector control decision making and implementation of resistance management strategy.

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.

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