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PhD Offer | Population genetics of an invasive species : the tiger mosquito Aedes albopictus

par Webmaster - 17 février 2016 ( dernière mise à jour : 8 mars 2016 )

To apply, contact laurence.despres@ujf-grenoble.fr before March 20th 2016

The tiger mosquito Aedes albopictus (Culicidae) is native from South-East Asia, and is currently expanding its range worldwide, including in non-tropical regions (Europe, USA). This anthropophilous mosquito is particularly competitive and active all day, which greatly increases the nuisance in densely populated areas. In addition, major viruses transmitted by the Aedes (dengue , chikungunya , yellow fever), have quickly adapted to this new vector which is now the primary vector in urban areas of these viruses. The socioeconomic impact of this mosquito is considerable. The objectives are 1) to analyze the genetic diversity of invasive mosquito tiger populations by using high throughput sequencing technics (double digest Restriction Amplified DNA sequencing) and 2) to determine which environmental factors constrain/favor the dispersal of this species. The genetic diversity of invasive populations on the colonization front in Europe will be compared to that of the oldest settled populations in Europe and from other continents, and the history of the invasion will be elucidated (phylogeography) : this will allow identifying the main colonization pathways of this mosquito in Europe, and barriers to dispersal. The hypothesis of a human-aided dispersal via road networks versus natural dispersal by flight (isolation by distance) will be tested. Mosquitoes relying on water for reproduction, the hydraulic network could also be an important factor of population structure. The local factors (climate, roads, land use, human population density, insecticide spaying...) can influence the dispersion and the population size of the tiger mosquito, but can also be selective factors, acting on a limited number of genes (local adaptation). There is no doubt that the tiger mosquito has acquired recently key adaptive mechanisms (eg, winter diapause ...) that allowed this species to invade temperate environments so quickly, but increased tolerance to insecticides could also be a factor favoring its expansion. The efficiency of Bacillus thuringiensis israelensis (Bti) spores to kill the larvae of this species will be tested on the studied populations ; indeed, this bio-insecticide is the main environmentally friendly control tool available against this invasive species, but its sustainable use relies on the lack of resistance evolution in target populations. The identification of environmental variables that promote the expansion of the tiger mosquito will better predict areas at risk of invasion and better target mosquito control measures and / or prevention to limit / circumscribe the expansion.

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