African Water Storage Pots for the Delivery of the Entomopathogenic Fungus Metarhizium anisopliae to the Malaria Vectors Anopheles gambiae s.s. and Anopheles funestus

Abstract Background Reducing the burden of malaria requires better understanding of vector populations particularly in forested regions where the incidence remains elevated. Here, we characterized malaria vectors in a locality near the international airport of Yaoundé, the capital city of Cameroon, including species composition, abundance, Plasmodium infection rate; insecticide resistance profiles and underlying resistance mechanisms. Methods Blood-fed adult mosquitoes resting indoors were aspirated from houses in April 2019 at Elende, a village located 2km from the Yaoundé-Nsimalen airport. Female mosquitoes were forced to lay eggs to generate F 1 adult progeny. WHO bioassays were performed to assess resistance profile to insecticides. The threshold of insecticide susceptibility was fixed above 98% mortality rate and mortality rates below 90% were considered indicative of confirmed insecticide resistance according to the WHO test procedures for insecticide resistance monitoring. Furthermore, the molecular basis of resistance and Plasmodium infection rates were investigated.Results Anopheles funestus s.s. was most abundant species in Elende (85%) followed by Anopheles gambiae s.s. (15%) with both having a similar sporozoite infection rate. Both species exhibited high levels of resistance to pyrethroids (<40% mortality). An. gambiae s.s. was also resistant to DDT (9.9% mortality) and bendiocarb (54% mortality) while susceptible to organophosphate. An. funestus s.s. was resistant to dieldrin (1% mortality), DDT (86% mortality) but susceptible to carbamates and organophosphates. The DDT/pyrethroid L119F-GSTe2 resistance allele (8%) and G119S ace -1 resistance allele (15%) were detected in An. funestus s.s. and An. gambiae s.s. respectively. Furthermore, the high pyrethroid/DDT resistances in An. gambiae s.s. corresponded with an increase frequency of 1014F kdr allele (95%). The CYP6P9a P450 resistance allele was absent in the An. funestus s.s. population meanwhile transcriptional profiling of candidate cytochrome P450 genes reveals the over-expression of CYP6P5 , CYP6P9a and CYP6P9b. Conclusion The resistance to multiple insecticide classes observed in these vector populations alongside the high Plasmodium infection rate highlights the challenges that public health vector control programs encounter in sustaining the regular effectiveness of contemporary insecticide-based control interventions in forested areas. More particularly, the resistance observed against the carbamates and possible resistance against the organophosphates constitutes a major concern for IRS.

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

Journal of Medical Entomology ◽

10.1093/jme/tjaa195 ◽

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.

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

PLoS ONE ◽

10.1371/journal.pone.0215669 ◽

2019 ◽

Vol 14 (4) ◽

pp. e0215669 ◽

Cited By ~ 1

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

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Environmental factors associated with the malaria vectors Anopheles gambiae and Anopheles funestus in Kenya

Malaria Journal ◽

10.1186/1475-2875-8-268 ◽

2009 ◽

Vol 8 (1) ◽

Cited By ~ 62

Author(s):

Louise A Kelly-Hope ◽

Janet Hemingway ◽

F Ellis McKenzie

Keyword(s):

Environmental Factors ◽

Anopheles Gambiae ◽

Anopheles Funestus ◽

Malaria Vectors ◽

Factors Associated

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Wide cross-reactivity between Anopheles gambiae and Anopheles funestus SG6 salivary proteins supports exploitation of gSG6 as a marker of human exposure to major malaria vectors in tropical Africa

Malaria Journal ◽

10.1186/1475-2875-10-206 ◽

2011 ◽

Vol 10 (1) ◽

pp. 206 ◽

Cited By ~ 34

Author(s):

Cinzia Rizzo ◽

Raffaele Ronca ◽

Gabriella Fiorentino ◽

Valentina D Mangano ◽

Sodiomon B Sirima ◽

...

Keyword(s):

Anopheles Gambiae ◽

Human Exposure ◽

Anopheles Funestus ◽

Cross Reactivity ◽

Malaria Vectors ◽

Salivary Proteins ◽

Tropical Africa ◽

Wide Cross

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16S rRNA Gene-Based Identification of Midgut Bacteria from Field-Caught Anopheles gambiae Sensu Lato and A. funestus Mosquitoes Reveals New Species Related to Known Insect Symbionts

Applied and Environmental Microbiology ◽

10.1128/aem.71.11.7217-7223.2005 ◽

2005 ◽

Vol 71 (11) ◽

pp. 7217-7223 ◽

Cited By ~ 134

Author(s):

Jenny M. Lindh ◽

Olle Terenius ◽

Ingrid Faye

Keyword(s):

16S Rrna ◽

Anopheles Gambiae ◽

Bacterial Species ◽

Anopheles Funestus ◽

16S Rrna Genes ◽

Rrna Genes ◽

Malaria Vectors ◽

Rrna Gene ◽

Species Determination ◽

Insect Symbionts

ABSTRACT Field-collected mosquitoes of the two main malaria vectors in Africa, Anopheles gambiae sensu lato and Anopheles funestus, were screened for their midgut bacterial contents. The midgut from each blood-fed mosquito was screened with two different detection pathways, one culture independent and one culture dependent. Bacterial species determination was achieved by sequence analysis of 16S rRNA genes. Altogether, 16 species from 14 genera were identified, 8 by each method. Interestingly, several of the bacteria identified are related to bacteria known to be symbionts in other insects. One isolate, Nocardia corynebacterioides, is a relative of the symbiont found in the vector for Chagas' disease that has been proven useful as a paratransgenic bacterium. Another isolate is a novel species within the γ-proteobacteria that could not be phylogenetically placed within any of the known orders in the class but is close to a group of insect symbionts. Bacteria representing three intracellular genera were identified, among them the first identifications of Anaplasma species from mosquitoes and a new mosquito-Spiroplasma association. The isolates will be further investigated for their suitability for a paratransgenic Anopheles mosquito.

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

Journal of Medical Entomology ◽

10.1093/jme/tjz030 ◽

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.

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

Frontiers in Tropical Diseases ◽

10.3389/fitd.2021.739771 ◽

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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Entomological Indicators of Malaria Transmission Prior to a Cluster Randomised Controlled Trial of a “Lethal House Lure” Intervention in Central Côte D’Ivoire

10.21203/rs.3.rs-1146656/v1 ◽

2021 ◽

Author(s):

Rosine Zlanneu Wolie ◽

Alphonsine A. Koffi ◽

Lesley Ayuk-Taylor ◽

Ludovic P. Ahoua Alou ◽

Eleanore D. Sternberg ◽

...

Keyword(s):

Anopheles Gambiae ◽

Malaria Transmission ◽

Cote D'ivoire ◽

Côte D’Ivoire ◽

Controlled Trial ◽

Anopheles Funestus ◽

Malaria Vectors ◽

Cote D’Ivoire ◽

Côte D'ivoire ◽

Indoor And Outdoor

Abstract Background: A study was conducted prior to implementing a cluster randomised controlled trial (CRT) of a lethal house lure strategy in central Côte d’Ivoire and aimed to provide baseline information on malaria vectors in 40 village clusters. Methods: Human landing catches (HLC) was performed between November-December 2016, capturing mosquitoes indoor and outdoor between 18.00-08.00. Mosquitoes were processed for entomological indicators of malaria transmission (human biting rates, parity rates, sporozoite infection rates and the entomological inoculation rates (EIR)). Species composition and allelic frequencies of Kdr-w and Ace-1R mutations were also investigated within the Anopheles gambiae complex. Results: Overall, 15,632 mosquitoes were captured. Anopheles gambiae s.l. and Anopheles funestus were the two malaria vectors found during the survey period, with predominance for Anopheles gambiae s.l. (66.2%) compared to Anopheles funestus (10.3%). The mean biting rate for An. gambiae s.l. was almost 5 times higher than that for An. funestus s.l.(19.8 bites per person per night for An. gambiae s. l. vs 4.3 bites per person per night for An. funestus s. l.) and this was evident indoor and outdoor. An. funestus was more competent to transmit malaria parasites in the study area, despite relatively lower number tested for sporozoite index (1.6% (1,373) for An. gambiae vs 4.7 % (722) for An. funestus s.l.). There was no significant difference between the proportion infected outdoor and indoor for An. gambiae s.l. (1.6% vs 1.5%; OR=1.11[0.65-1.9]; P=0.676), but for An. funestus, more mosquitoes were infected outdoor (6.4%) than indoor (3.5%) (OR=1.86 [1.07-3.23]; P=0.0249). The majority of both infected vectors with malaria parasites harboured P. falciparum (90.6% for An. gambiae s. l. and 97, 8% for An. funestus s. l.). The EIR for both vectors (0.43 infected bites per night) were similar and there were no significant differences for transmission occurring outdoor and indoor for both species. Of the An. gambiae s.l. analysed, only An. gambiae (14.1%) and An. coluzzii (85.9%) were found. The allelic frequencies of Kdr and Ace-1R were higher in An. gambiae (0.97 for Kdr and 0.19 for Ace-1R) than in An. coluzzii (0.86 for Kdr and 0.10 for Ace-1R) (P<0.001).Conclusion: Despite universal coverage of long-lasting insecticidal nets (LLINs) in the area, there was an abundance of malaria vectors in the study in area in central Côte d’Ivoire, specifically highly resistant An. gambiae s.l. as well as An. funestus s.l.. The malaria sporozoite rate was higher in An. funestus s.l than An. gambiae s.l.. but EIR rates in these two species were similarly high, both indoor and outdoor. Novel tools or strategies are urgently needed to further reduce malaria transmission in this area.

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