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Why are anopheline mosquitoes not present in the Seychelles?

DOI: 10.1186/1475-2875-10-31

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In order to re-examine the absence of anopheline mosquitoes in the Seychelles, an entomological field survey was conducted in December 2008 at 17 sites on four granitic islands, including Mahé and Praslin, and ten sites on coralline atolls in the extreme west, including Aldabra.No evidence of larval or adult anophelines was found at the surveyed sites, which supports their absence in the Seychelles.In the granitic islands of the Seychelles, the climate is favourable for anophelines. However, these islands are protected by their remoteness and prevailing seasonal winds. In addition, stagnant freshwater, required in anopheline larval development, is relatively uncommon on the granitic islands because of the steep slopes. In the southwestern atolls (Aldabra and Providence-Farquhar groups), the presence of a long dry season of up to nine months and the total absence of permanent natural freshwater prevents the breeding of anophelines and their successful colonization. The Seychelles does not have any native land mammals and like in other parts of the world (Antarctica, Iceland, New Caledonia, Central Pacific islands) their absence is associated with the lack of anophelines. This suggests an obligatory relationship for anophelines to feed on terrestrial mammals, without alternative for blood-feeding sources, such as bats, birds and reptiles.Plasmodium parasites are transmitted by mosquitoes (family Culicidae). Malaria parasites of mammals, including humans, are exclusively transmitted by mosquitoes belonging to the genus Anopheles. These anophelines are observed virtually worldwide, although the distribution of a given Anopheles species varies from being highly localized to sub-continental. For example, on the one hand Anopheles bwambae occurs exclusively within a 10 km radius of geothermal springs in Bwamba, Uganda, and, on the other hand, Anopheles messeae is found in most of Eurasia from Ireland to Central Siberia [1,2].The examples of areas without anophelines are li

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