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Genetic structure of the tiger mosquito, Aedes albopictus, in Cameroon (Central Africa).

Kamgang B, Brengues C, Fontenille D, Njiokou F, Simard F, Paupy C - PLoS ONE (2011)

Bottom Line: Recent genetic studies of invasive species have shown that multiple introductions are a key factor for successful expansion in new areas.All the microsatellite markers were successfully amplified and were polymorphic, showing moderate genetic structureamong geographic populations (F(ST)  = 0.068, P < 0.0001).The genetic structure of natural populations points to multiple introductions from tropical regions.

View Article: PubMed Central - PubMed

Affiliation: Unité Mixte de Recherche MIVEGEC, UM1-CNRS 5290-IRD 224, Institut de Recherche pour le Développement, Montpellier, France.

ABSTRACT

Background: Aedes albopictus (Skuse, 1884) (Diptera: Culicidae), a mosquito native to Asia, has recently invaded all five continents. In Central Africa it was first reported in the early 2000s, and has since been implicated in the emergence of arboviruses such as dengue and chikungunya in this region. Recent genetic studies of invasive species have shown that multiple introductions are a key factor for successful expansion in new areas. As a result, phenotypic characters such as vector competence and insecticide susceptibility may vary within invasive pest species, potentially affecting vector efficiency and pest management. Here we assessed the genetic variability and population genetics of Ae. albopictus isolates in Cameroon (Central Africa), thereby deducing their likely geographic origin.

Methods and results: Mosquitoes were sampled in 2007 in 12 localities in southern Cameroon and analyzed for polymorphism at six microsatellite loci and in two mitochondrial DNA regions (ND5 and COI). All the microsatellite markers were successfully amplified and were polymorphic, showing moderate genetic structureamong geographic populations (F(ST)  = 0.068, P < 0.0001). Analysis of mtDNA sequences revealed four haplotypes each for the COI and ND5 genes, with a dominant haplotype shared by all Cameroonian samples. The weak genetic variation estimated from the mtDNA genes is consistent with the recent arrival of Ae. albopictus in Cameroon. Phylogeographic analysis based on COI polymorphism indicated that Ae. albopictus populations from Cameroon are related to tropical rather than temperate or subtropical outgroups.

Conclusion: The moderate genetic diversity observed among Cameroonian Ae. albopictus isolates is in keeping with recent introduction and spread in this country. The genetic structure of natural populations points to multiple introductions from tropical regions.

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Dendrogram based on microsatellite Nei's genetic distance [37] clustering by UPGMA methods.The genetic relationship among 12 Ae. albopictus populations sampled in Cameroon is shown.
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pone-0020257-g002: Dendrogram based on microsatellite Nei's genetic distance [37] clustering by UPGMA methods.The genetic relationship among 12 Ae. albopictus populations sampled in Cameroon is shown.

Mentions: Overall genetic differentiation between samples was moderate and statistically significant (FST = 0.068, P<0.0001). Pairwise analysis of populations indicated significant genetic differentiation for most sample pairs (61/66), associated with FST estimates ranging from 0.006 (Bertoua-Abong-Mbang) to 0.176 (Buea-Yaounde) (Table 3). The UPGMA unrooted tree constructed with pairwise genetic distances and bootstrap values supporting node clearly indicated that the Buea sample was genetically distant from all the other samples (Figure 2). The topology of the tree shown in Figure 2 suggested that the pattern of genetic differentiation was not shaped by the geographic distance between sampling sites, in agreement with Mantel's test (P = 0.33). Bayesian cluster analysis identified 2 distinct genetic clusters in the dataset, although most of geographic populations appeared as a mixture of specimens from the two clusters except Buea and Garoua-Boulaï that appear made up of a single dominant cluster (see Figure S1).


Genetic structure of the tiger mosquito, Aedes albopictus, in Cameroon (Central Africa).

Kamgang B, Brengues C, Fontenille D, Njiokou F, Simard F, Paupy C - PLoS ONE (2011)

Dendrogram based on microsatellite Nei's genetic distance [37] clustering by UPGMA methods.The genetic relationship among 12 Ae. albopictus populations sampled in Cameroon is shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3101236&req=5

pone-0020257-g002: Dendrogram based on microsatellite Nei's genetic distance [37] clustering by UPGMA methods.The genetic relationship among 12 Ae. albopictus populations sampled in Cameroon is shown.
Mentions: Overall genetic differentiation between samples was moderate and statistically significant (FST = 0.068, P<0.0001). Pairwise analysis of populations indicated significant genetic differentiation for most sample pairs (61/66), associated with FST estimates ranging from 0.006 (Bertoua-Abong-Mbang) to 0.176 (Buea-Yaounde) (Table 3). The UPGMA unrooted tree constructed with pairwise genetic distances and bootstrap values supporting node clearly indicated that the Buea sample was genetically distant from all the other samples (Figure 2). The topology of the tree shown in Figure 2 suggested that the pattern of genetic differentiation was not shaped by the geographic distance between sampling sites, in agreement with Mantel's test (P = 0.33). Bayesian cluster analysis identified 2 distinct genetic clusters in the dataset, although most of geographic populations appeared as a mixture of specimens from the two clusters except Buea and Garoua-Boulaï that appear made up of a single dominant cluster (see Figure S1).

Bottom Line: Recent genetic studies of invasive species have shown that multiple introductions are a key factor for successful expansion in new areas.All the microsatellite markers were successfully amplified and were polymorphic, showing moderate genetic structureamong geographic populations (F(ST)  = 0.068, P < 0.0001).The genetic structure of natural populations points to multiple introductions from tropical regions.

View Article: PubMed Central - PubMed

Affiliation: Unité Mixte de Recherche MIVEGEC, UM1-CNRS 5290-IRD 224, Institut de Recherche pour le Développement, Montpellier, France.

ABSTRACT

Background: Aedes albopictus (Skuse, 1884) (Diptera: Culicidae), a mosquito native to Asia, has recently invaded all five continents. In Central Africa it was first reported in the early 2000s, and has since been implicated in the emergence of arboviruses such as dengue and chikungunya in this region. Recent genetic studies of invasive species have shown that multiple introductions are a key factor for successful expansion in new areas. As a result, phenotypic characters such as vector competence and insecticide susceptibility may vary within invasive pest species, potentially affecting vector efficiency and pest management. Here we assessed the genetic variability and population genetics of Ae. albopictus isolates in Cameroon (Central Africa), thereby deducing their likely geographic origin.

Methods and results: Mosquitoes were sampled in 2007 in 12 localities in southern Cameroon and analyzed for polymorphism at six microsatellite loci and in two mitochondrial DNA regions (ND5 and COI). All the microsatellite markers were successfully amplified and were polymorphic, showing moderate genetic structureamong geographic populations (F(ST)  = 0.068, P < 0.0001). Analysis of mtDNA sequences revealed four haplotypes each for the COI and ND5 genes, with a dominant haplotype shared by all Cameroonian samples. The weak genetic variation estimated from the mtDNA genes is consistent with the recent arrival of Ae. albopictus in Cameroon. Phylogeographic analysis based on COI polymorphism indicated that Ae. albopictus populations from Cameroon are related to tropical rather than temperate or subtropical outgroups.

Conclusion: The moderate genetic diversity observed among Cameroonian Ae. albopictus isolates is in keeping with recent introduction and spread in this country. The genetic structure of natural populations points to multiple introductions from tropical regions.

Show MeSH
Related in: MedlinePlus