Survey of the mosquitoes (Diptera: Culicidae) of Mayotte

Abstract

A transversal survey of immature mosquitoes was conducted on Mayotte Island (France) in the Comoros Archipelago, western Indian Ocean, with the aim to inventory the Culicidae and to document inter-species relationships in different habitats. In total 420 habitats were sampled for larvae and/or pupae mosquitoes, resulting in more than 6,000 specimens. Forty species belonging to 15 genera were collected, with eight taxa integrated for the first time to the Mayotte mosquito list. The most frequently recorded species were Stegomyia aegypti, St. albopicta, Anopheles gambiae and Eretmapodites subsimplicipes, the first three species being known vectors of viruses and parasites transmitted to humans. Mean species richness in habitats ranged from 1.00 to 3.29, with notable differences between habitats. For example, water-filled axils of banana leaves, tree-holes and crab-holes had low species richness, while cut bamboo, water pools, abandoned tires and marsh and swamp water had notably higher species richness. Twenty-seven mosquito species belonging to 12 genera were routinely collected (in ≥20% of at least one type of larval habitat) suggesting that multiple species play a role in the biocenosis of these aquatic habitats. Multispecies association was observed in 52% of the habitats. The co-occurrence of up to six species belonging to five genera was recorded in a single habitat. The mosquitoes of Mayotte show notable biogeographical affinities to those of Madagascar, as compared to the African continent. These two potential source areas are nearly equidistant from Mayotte, which in turn indicates biased dispersal from east to west. Our findings suggest that with relatively short-term intensive sampling in different habitats, it is possible to approach exhaustive species inventories based on collection of larvae. Mayotte, with its modest elevation range and land surface, has a notable species richness of mosquitoes with 45 well-documented species belonging to 15 genera.

Figure 1. Prospecting effort associated with larval mosquito inventories on Mayotte during the 2008–2012 surveys.

In total, 420 habitats yielded mosquito collections and in certain cases, theseare in close proximity and overlap as a single point on the map.

Figure 2. Species accumulation curve for the 40 mosquito species observed on Mayotte at 420 habitats during the 2008–2012 surveys.

Bars indicate two standard deviations.

Figure 3. Frequency histograms for the number of mosquito genera and species versus the number of larval habitats (n = 420) on Mayotte during the 2008–2012 surveys.

Figure 4. Correspondence analysis for the 18 main types of larval habitats vs. the 27 principally collected mosquito species.

Represented here are axis 1 (horizontal) and axis 3 (vertical) that explained 33.3% (22.9%+11.4%) of total variance; the scales are equal for the two graphs (grid step size = 1). The separation along axis 1 follows a temporal gradient from non-permanent (axils of banana-pineapple, taro and Typhonodorum plants) to permanent habitats (marsh and swamp water, water pools during the rainy season and slow flowing water). Axis 3 displays another gradient from habitats with restricted openings (crab-holes, tree-holes) to habitats with open access (mushroom caps, fallen leaf litter and snail shells).

Figure 5. Diagrammatic representation of the known distribution of the 44 mosquito species occurring on Mayotte.

Four species are considered as endemic to Mayotte and three others endemic to the greater Comoros Archipelago. Most species occur on Madagascar and the African continent, and of biogeographic interest, 10 are shared with Madagascar and one with the African continent. Culex sp. A is not listed as its specific identification needs further documentation (see Text S1). Species are listed in alphabetic order.