Anopheles funestus is a primary vector of malaria in Africa south of the Sahara. We assessed its rangewide population genetic structure based on samples from 11 countries, using 10 physically mapped microsatellite loci, two per autosome arm and the X (N = 548), and 834 bp of the mitochondrial ND5 gene (N = 470). On the basis of microsatellite allele frequencies, we found three subdivisions: eastern (coastal Tanzania, Malawi, Mozambique and Madagascar), western (Burkina Faso, Mali, Nigeria and western Kenya), and central (Gabon, coastal Angola). A. funestus from the southwest of Uganda had affinities to all three subdivisions. Mitochondrial DNA (mtDNA) corroborated this structure, although mtDNA gene trees showed less resolution. The eastern subdivision had significantly lower diversity, similar to the pattern found in the codistributed malaria vector Anopheles gambiae. This suggests that both species have responded to common geographic and/or climatic constraints. The western division showed signatures of population expansion encompassing Kenya west of the Rift Valley through Burkina Faso and Mali. This pattern also bears similarity to A. gambiae, and may reflect a common response to expanding human populations following the development of agriculture. Due to the presumed recent population expansion, the correlation between genetic and geographic distance was weak. Mitochondrial DNA revealed further cryptic subdivision in A. funestus, not detected in the nuclear genome. Mozambique and Madagascar samples contained two mtDNA lineages, designated clade I and clade II, that were separated by two fixed differences and an average of 2% divergence, which implies that they have evolved independently for approximately 1 million years. Clade I was found in all 11 locations, whereas clade II was sampled only on Madagascar and Mozambique. We suggest that the latter clade may represent mtDNA capture by A. funestus, resulting from historical gene flow either among previously isolated and divergent populations or with a related species.
Aedes aegypti, the major vector of dengue, yellow fever, chikungunya, and Zika viruses, remains of great medical and public health concern. There is little doubt that the ancestral home of the species is Africa. This mosquito invaded the New World 400‐500 years ago and later, Asia. However, little is known about the genetic structure and history of Ae. aegypti across Africa, as well as the possible origin(s) of the New World invasion. Here, we use ~17,000 genome‐wide single nucleotide polymorphisms (SNPs) to characterize a heretofore undocumented complex picture of this mosquito across its ancestral range in Africa. We find signatures of human‐assisted migrations, connectivity across long distances in sylvan populations, and of local admixture between domestic and sylvan populations. Finally, through a phylogenetic analysis combined with the genetic structure analyses, we suggest West Africa and especially Angola as the source of the New World's invasion, a scenario that fits well with the historic record of 16th‐century slave trade between Africa and Americas.
Between the 16th and 18th centuries, Aedes aegypti (Diptera: Culicidae), a mosquito native to Africa, invaded the Americas, where it was successively responsible for the emergence of yellow fever (YF) and dengue (DEN). The species was eradicated from numerous American countries in the mid-20th century, but re-invaded them in the 1970s and 1980s. Little is known about the precise identities of Ae. aegypti populations which successively thrived in South America, or their relation with the epidemiological changes in patterns of YF and DEN. We examined these questions in Bolivia, where Ae. aegypti, eradicated in 1943, re-appeared in the 1980s. We assessed the genetic variability and population genetics of Ae. aegypti samples in order to deduce their genetic structure and likely geographic origin. Using a 21-population set covering Bolivia, we analyzed the polymorphism at nine microsatellite loci and in two mitochondrial DNA regions (COI and ND4). Microsatellite markers revealed a significant genetic structure among geographic populations (F(ST)=0.0627, P<0.0001) in relation with the recent re-expansion of Ae. aegypti in Bolivia. Analysis of mtDNA sequences revealed the existence of two genetic lineages, one dominant lineage recovered throughout Bolivia, and the second restricted to rural localities in South Bolivia. Phylogenic analysis indicated that this minority lineage was related to West African Ae. aegypti specimens. In conclusion, our results suggested a temporal succession of Ae. aegypti populations in Bolivia, that potentially impacted the epidemiology of dengue and yellow fever.
An updated checklist of 235 mosquito species from Madagascar is presented. The number of species has increased considerably compared to previous checklists, particularly the last published in 2003 (178 species). This annotated checklist provides concise information on endemism, taxonomic position, developmental stages, larval habitats, distribution, behavior, and vector-borne diseases potentially transmitted. The 235 species belong to 14 genera: Aedeomyia (3 species), Aedes (35 species), Anopheles (26 species), Coquillettidia (3 species), Culex (at least 50 species), Eretmapodites (4 species), Ficalbia (2 species), Hodgesia (at least one species), Lutzia (one species), Mansonia (2 species), Mimomyia (22 species), Orthopodomyia (8 species), Toxorhynchites (6 species), and Uranotaenia (73 species). Due to non-deciphered species complexes, several species remain undescribed. The main remarkable characteristic of Malagasy mosquito fauna is the high biodiversity with 138 endemic species (59%). Presence and abundance of species, and their association, in a given location could be a bio-indicator of environmental particularities such as urban, rural, forested, deforested, and mountainous habitats. Finally, taking into account that Malagasy culicidian fauna includes 64 species (27%) with a known medical or veterinary interest in the world, knowledge of their biology and host preference summarized in this paper improves understanding of their involvement in pathogen transmission in Madagascar.
Abstract. Aedes mosquitoes are important vectors of re-emerging diseases in developing countries, and increasing exposure to Aedes in the developed world is currently a source of concern. Given the limitations of current entomologic methods, there is a need for a new effective way for evaluating Aedes exposure. Our objective was to evaluate specific antibody responses to Aedes aegypti saliva as a biomarker for vector exposure in a dengue-endemic urban area. IgG responses to saliva were strong in young children and steadily waned with age. Specific IgG levels were significantly higher in persons living in sites with higher Ae. aegypti density, as measured by using entomologic parameters. Logistic regression showed a significant correlation between IgG to saliva and exposure level, independently of either age or sex. These results suggest that antibody responses to saliva could be used to monitor human exposure to Aedes bites.
Background: Malaria is a former endemic problem in the Camargue, South East France, an area from where very few recent data concerning Anopheles are available. A study was undertaken in 2005 to establish potential malaria vector biology and dynamics and evaluate the risk of malaria reemergence.
BackgroundTo develop an efficient sterile insect technique (SIT) programme, the number of sterile males to release, along with the spatial and temporal pattern of their release, has to be determined. Such parameters could be estimated from a reliable estimation of the wild population density (and its temporal variation) in the area to treat. Here, a series of mark-release-recapture experiments using laboratory-reared and field-derived Aedes albopictus males were carried out in Duparc, a selected pilot site for the future application of SIT in the north of La Reunion Island.MethodsThe dispersal, longevity of marked males and seasonal fluctuations in the population size of native mosquitoes were determined from the ratio of marked to unmarked males caught in mice-baited BG-Sentinel traps. The study was conducted during periods of declining population abundance (April), lowest abundance (September) and highest abundance (December).ResultsAccording to data collected in the first 4 days post-release, the Lincoln index estimated population size as quite variable, ranging from 5817 in April, to 639 in September and 5915 in December. Calculations of daily survival probability to 4 days after release for field and laboratory males were 0.91 and 0.98 in April, respectively, and 0.88 and 0.84 in September, respectively. The mean distance travelled (MDT) of released field males were 46 m, 67 m and 37 m for December, April and September experiments, respectively. For released laboratory males, the MDT was 65 m and 42 m in April and September, respectively.ConclusionsTheoretically, the most efficient release programme should be started in July/August when the mosquito population size is the lowest (c.600 wild males/ha relative to 5000 wild males estimated for December and April), with a weekly release of 6000 males/ha. The limited dispersal of Ae. albopictus males highlights the nessecity for the widespread release of sterile males over multiple sites and in a field setting to avoid topographical barriers and anthropogenic features that may block the migration of the released sterile male mosquitoes.Electronic supplementary materialThe online version of this article (10.1186/s13071-019-3329-7) contains supplementary material, which is available to authorized users.
The Aedes aegypti mosquito is often considered to be among the most dangerous animal in the world due to its ability to transmit several arboviruses (yellow fever, dengue, chikungunya and Zika) that historically have taken a heavy toll on human health and continue to do so today (Powell, 2016). The European colonization of the New World was strongly affected by Ae. aegypti, and these events define the Americas today (McNeill, 2010). Beyond its direct role in disease transmission, this mosquito is easy to rear in the laboratory
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