Abstract
BackgroundIn recent years, the Asian tiger mosquito Aedes albopictus has emerged as a species of major medical concern following its global expansion and involvement in many arbovirus outbreaks. On Réunion Island, Ae. albopictus was responsible for a large chikungunya outbreak in 2005–2006 and more recently an epidemic of dengue which began at the end of 2017 and is still ongoing at the time of writing. This dengue epidemic has seen a high number of human cases in south and west coastal regions, while few cases have been reported in the north and east of the island. To better understand the role of mosquito populations in such spatial patterns of dengue virus transmission in Réunion Island, we examined the genetic diversity and population structure of Ae. albopictus sampled across the island.ResultsBetween November 2016 and March 2017, a total of 564 mosquitoes were collected from 19 locations in three main climatic regions (West, East and Center) of Réunion Island and were genotyped using 16 microsatellite loci. A high genetic diversity was observed with 2–15 alleles per locus and the average number of alleles per population varying between 4.70–5.90. Almost all FIS values were significantly positive and correlated to individual relatedness within populations using a hierarchical clustering approach based on principal components analyses (HCPC). However, the largest part of genetic variance was among individuals within populations (97%) while only 3% of genetic variance was observed among populations within regions. Therefore, no distinguishable population structure or isolation by distance was evidenced, suggesting high rates of gene flow at the island scale.ConclusionsOur results show high genetic diversity but no genetic structure of Ae. albopictus populations in Réunion Island thus reflecting frequent movements of mosquitoes between populations probably due to human activity. These data should help in the understanding of Ae. albopictus vector capacity and the design of effective mosquito control strategies.
Highlights
In recent years, the Asian tiger mosquito Aedes albopictus has emerged as a species of major medical concern following its global expansion and involvement in many arbovirus outbreaks
A high genetic diversity reflecting long‐term established mosquito populations The genetic diversity observed in the 19 Ae. albopictus populations was high: on average more than five alleles were observed per population and 530 Multi-locus genotypes (MLGs) were identified among the 532 mosquitoes examined
Vector control strategies could be applied at the island scale by taking into account environmental characteristics and mosquito population densities through time because gene flow between mosquito populations may have a limited impact in their effectiveness
Summary
The Asian tiger mosquito Aedes albopictus has emerged as a species of major medical concern following its global expansion and involvement in many arbovirus outbreaks. On Réunion Island, Ae. albopictus was responsible for a large chikungunya outbreak in 2005–2006 and more recently an epidemic of dengue which began at the end of 2017 and is still ongoing at the time of writing. This dengue epidemic has seen a high number of human cases in south and west coastal regions, while few cases have been reported in the north and east of the island. Ae. albopictus is one of the most abundant mosquito species in Réunion Island and is common all over the island in urban, periurban and rural areas sometimes reaching up 1200 m [17, 18]. Aedes albopictus gradually replaced Ae. aegypti whose distributional range was considerably reduced [17, 21, 22] probably due to dichlorodiphenyltrichloroethane (DDT) treatments for mosquito-control campaigns against malaria vectors in the 1950s [16]
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