Dataset Information

Population genetic structure of the major malaria vector Anopheles funestus s.s. and allied species in southern Africa.

ABSTRACT: BACKGROUND: Anopheles funestus s.s., one of the major malaria vectors in sub-Saharan Africa, belongs to a group of eleven African species that are morphologically similar at the adult stage, most of which do not transmit malaria. The population structure of An. funestus based on mitochondrial DNA data led to the description of two cryptic subdivisions, clade I widespread throughout Africa and clade II known only from Mozambique and Madagascar. In this study, we investigated five common members of the Anopheles funestus group in southern Africa in order to determine relationships within and between species. METHODS: A total of 155 specimens of An. funestus, An. parensis, An. vaneedeni, An. funestus-like and An. rivulorum from South Africa, Mozambique and Malawi were used for the study. The population genetic structure was assessed within and between populations using mitochondrial DNA. RESULTS: The phylogenetic trees revealed three main lineages: 1) An. rivulorum; 2) An. funestus-like clade I and An. parensis clade II; and 3) An. funestus clades I and II, An. funestus-like clade II, An. parensis clade I and An. vaneedeni clades I and II. Within An. funestus, 32 specimens from Mozambique consisted of 40.6% clade I and 59.4% clade II while all 21 individuals from Malawi were clade I. In the analysis of mitochondrial DNA sequences, there were 37 polymorphic sites and 9 fixed different nucleotides for ND5 and 21 polymorphic sites and 6 fixed different nucleotides for COI between the two An. funestus clades. The results for COI supported the ND5 analysis. CONCLUSION: This is the first report comparing An. funestus group species including An. funestus clades I and II and the new species An. funestus-like. Anopheles funestus clade I is separated from the rest of the members of the An. funestus subgroup and An. funestus-like is distinctly distributed from the other species in this study. However, there were two clades for An. funestus-like, An. parensis and An. vaneedeni. Further investigations are needed to determine what these results mean in terms of the specific status of the clades within each taxon and whether this has any epidemiological implications for malaria transmission.

SUBMITTER: Choi KS

PROVIDER: S-EPMC3533957 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Population genetic structure of the major malaria vector Anopheles funestus s.s. and allied species in southern Africa.

Choi Kwang Shik KS Koekemoer Lizette L LL Coetzee Maureen M

Parasites & vectors 20121206

<h4>Background</h4>Anopheles funestus s.s., one of the major malaria vectors in sub-Saharan Africa, belongs to a group of eleven African species that are morphologically similar at the adult stage, most of which do not transmit malaria. The population structure of An. funestus based on mitochondrial DNA data led to the description of two cryptic subdivisions, clade I widespread throughout Africa and clade II known only from Mozambique and Madagascar. In this study, we investigated five common me ...[more]

PMID: 23216696

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Project description:BackgroundAggravation of insecticide resistance in malaria vectors is threatening the efforts to control malaria by reducing the efficacy of insecticide-based interventions hence needs to be closely monitored. This study investigated the intensity of insecticide resistance of two major malaria vectors An. funestus sensu stricto (s.s.) and An. gambiae sensu lato (s.l.) collected in southern Ghana and assessed the bio-efficacy of several long-lasting insecticidal nets (LLINs) against these mosquito populations.MethodsThe insecticide susceptibility profiles of Anopheles funestus s.s. and Anopheles gambiae s.l. populations from Obuasi region (Atatam), southern Ghana were characterized and the bio-efficacy of some LLINs was assessed to determine the impact of insecticide resistance on the effectiveness of these tools. Furthermore, molecular markers associated with insecticide resistance in both species were characterized in the F0 and F1 populations using PCR and qPCR methods.ResultsAnopheles funestus s.s. was the predominant species and was resistant to pyrethroids, organochlorine and carbamate insecticides, but fully susceptible to organophosphates. An. gambiae s.l. was resistant to all four insecticide classes. High intensity of resistance to 5 × and 10 × the discriminating concentration (DC) of pyrethroids was observed in both species inducing a considerable loss of efficacy of long-lasting insecticidal nets (LLINs). Temporal expression analysis revealed a massive 12-fold increase in expression of the CYP6P4a cytochrome P450 gene in An. funestus s.s., initially from a fold change of 41 (2014) to 500 (2021). For both species, the expression of candidate genes did not vary according to discriminating doses. An. gambiae s.l. exhibited high frequencies of target-site resistance including Vgsc-1014F (90%) and Ace-1 (50%) while these mutations were absent in An. funestus s.s.ConclusionsThe multiple and high intensity of resistance observed in both malaria vectors highlights the need to implement resistance management strategies and the introduction of new insecticide chemistries.

Project description:BackgroundUnderstanding the molecular basis of insecticide resistance is key to improve the surveillance and monitoring of malaria vector populations under control. In the major malaria vector Anopheles funestus, little is currently known about the role of the knockdown resistance (kdr) mechanism. Here, we investigated the presence and contribution of knockdown resistance (kdr) to pyrethroids/DDT resistance observed in Anopheles funestus across Africa.ResultsPyrosequencing genotyping and sequencing of the voltage gated sodium channel (VGSC) gene did not detect the common L1014F mutation in field collected An. funestus across Africa. Amplification and cloning of the full-length of the sodium channel gene in pyrethroid resistant mosquitoes revealed evidences of alternative splicing events with three transcripts of 2092, 2061 and 2117 amino acids (93% average similarity to An. gambiae). Several amino acid changes were detected close to the domain II of the protein such as L928R, F938 W, I939S, L802S and T1008 M. However, all these mutations are found at low frequency and their role in pyrethroid resistance could not be established. The presence of the exclusive alternative splicing at exon 19 was not associated with resistance phenotype. Analysis of patterns of genetic diversity of the VGSC gene revealed a high polymorphism level of this gene across Africa with no evidence of directional selection suggesting a limited role for knockdown resistance in pyrethroid resistance in An. funestus. Patterns of genetic differentiation correlate with previous observations of the existence of barriers to gene flow Africa-wide with southern population significantly differentiated from other regions.ConclusionDespite an apparent limited role of knockdown resistance in An. funestus, it is necessary to continue to monitor the contribution of the mutations detected here as increasing selection from insecticide-based interventions may change the dynamic in field populations as previously observed in other vectors.

Dataset Information

Population genetic structure of the major malaria vector Anopheles funestus s.s. and allied species in southern Africa.

Publications

Population genetic structure of the major malaria vector Anopheles funestus s.s. and allied species in southern Africa.

Similar Datasets

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