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Abstract BackgroundUrbanization can influence disease vectors by altering larval habitat, microclimates, and host abundance. The global increase in urbanization, especially in Africa, is likely to alter vector abundance and pathogen transmission. We investigated the effect of urbanization and weather on the abundance of two mosquitoes,Aedes aegyptiandAedes albopictus, and infection with dengue, chikungunya, and Zika viruses at 63 sites in six cities spanning a 900-km latitudinal range in Cameroon, Central Africa. MethodsWe used human landing catches and backpack-mounted aspirators to sample mosquitoes and collected larval habitat, host availability, and weather (temperature, precipitation, humidity) data for each site in each city. We analyzed land use and land cover information and satellite photos at varying radii around sites (100 m to 2 km) to quantify the extent of urbanization and the number of structures around each site. We used a continuous urbanization index (UI; range 0–100) that increased with impermeable surface and decreased with forest cover. ResultsUrbanization increased larval habitat, human host availability, andAe. aegyptimosquito abundance.Aedes aegyptiabundance increased 1.7% (95% CI 0.69–2.7%) with each 1 unit increase in the urbanization index in all six cities (Douala, Kribi, Yaounde, Ngaoundere, Garoua, and Maroua) with a 5.4-fold increase from UI = 0 to UI = 100, and also increased with rainfall. In contrast,Ae. albopictusabundance increased with urbanization in one city, but showed no influence of urbanization in two other cites. Across three cities,Ae. albopictusabundance increased with rainfall, temperature, and humidity. Finally, we did not detect Zika, dengue, or chikungunya viruses in any specimens, and found weak evidence of interspecific competition in analyses of adult population growth rates. ConclusionsThese results show that urbanization consistently increasesAe. aegyptiabundance across a broad range of habitats in Central Africa, while effects onAe. albopictuswere more variable and the abundance of both species were influenced by rainfall. Future urbanization of Africa will likely increaseAe. aegyptiabundance, and climate change will likely alter abundance of both species through changes in precipitation and temperature. Graphical Abstract
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Genetic evidence for the origin of Aedes aegypti , the yellow fever mosquito, in the southwestern Indian Ocean
Abstract Aedes aegyptiis among the best‐studied mosquitoes due to its critical role as a vector of human pathogens and ease of laboratory rearing. Until now, this species was thought to have originated in continental Africa, and subsequently colonized much of the world following the establishment of global trade routes. However, populations of this mosquito on the islands in the southwestern Indian Ocean (SWIO), where the species occurs with its nearest relatives referred to as the Aegypti Group, have received little study. We re‐evaluated the evolutionary history ofAe. aegyptiand these relatives, using three data sets: nucleotide sequence data, 18,489 SNPs and 12 microsatellites. We found that: (a) the Aegypti Group diverged 16 MYA (95% HPD: 7–28 MYA) from its nearest African/Asian ancestor; (b) SWIO populations ofAe. aegyptiare basal to continental African populations; (c) after diverging 7 MYA (95% HPD: 4–15 MYA) from its nearest formally described relative (Ae. mascarensis),Ae. aegyptimoved to continental Africa less than 85,000 years ago, where it recently (<1,000 years ago) split into two recognized subspeciesAe. aegypti formosusand a human commensal,Ae. aegypti aegypti; (d) the Madagascar samples form a clade more distant from all otherAe. aegyptithan the named speciesAe. mascarensis, implying that Madagascar may harbour a new cryptic species; and (e) there is evidence of introgression betweenAe. mascarensisandAe. aegyption Réunion, and between the two subspecies elsewhere in the SWIO, a likely consequence of recent introductions of domesticAe. aegypti aegyptifrom Asia.
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- Award ID(s):
- 1754376
- PAR ID:
- 10452349
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Molecular Ecology
- Volume:
- 29
- Issue:
- 19
- ISSN:
- 0962-1083
- Format(s):
- Medium: X Size: p. 3593-3606
- Size(s):
- p. 3593-3606
- Sponsoring Org:
- National Science Foundation
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