Variation in the spatial distribution of Aedes aegypti and Aedes albopictus in Madagascar

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Raharinirina, Manou Rominah | Ayala, Diego | Lamy, Kévin | Andrianandrasana, Miora | Miharisoa, Sylviane | Le Goff, Gilbert | Fontenille, Didier | Walker, Thomas | Andriamandimby, Soa Fy | Girod, Romain | Paupy, Christophe | Tantely, Michaël Luciano

Edité par CCSD -

International audience. Aedes aegypti and Aedes albopictus, both vector of arbovirus, co-exist in Madagascar. Ae. aegypti has recently been reported to have originated from the islands of the southwest Indian Ocean, while Ae. albopictus is native to south-east Asia. Their geographic distribution and the epidemiology of the diseases they transmit are affected by variable climatic conditions. Changes in the distribution of these two species have been noticed in recent decades. This study aims to assess the dynamics of both species and identify the factors driving their distribution. For that, available unpublished and published data on the Aedes of Madagascar from 1904 to 2016 were compiled. Data from literature based-review, plus mosquito database from the Institut Pasteur de Madagascar and personal communications from close collaborators in Institut de Recherche pour le Développement were compiled. Furthermore, data from the longitudinal survey on adult and immature stages of Aedes (Stegomyia) carried out from Febuary to December 2019 in 25 districts of five bioclimatic domains of Madagascar were also used. The relationship between these entomological data and climatic, environmental, topographical and demographic data was analysed using statistical models. Our results demonstrated that low vegetation cover significantly determines the presence of Ae. Aegypti in Madagascar, with a slight variation in its climatic suitability over time. On the other hand, Ae. albopictus tends to colonise all five bioclimatic domains, and changes in relative humidity and rainfall over time influence its distribution. Human population density has no effect on neither presence nor absence of both species. Both species are climate-sensitive, but the adaptation speed does not seem to be the same. Joint species analyses need to be carried out in order to study the niche dynamics and niche overlap between them, as well as to compare their rate of invasion according to changes in their distribution area.

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