| Aedes polynesiensis | |
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| Species: | A. polynesiensis
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| Aedes polynesiensis Marks, 1951
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Aedes polynesiensis (also known as Polynesian tiger mosquito) is a member of the Aedes scutellaris group found only in a series of island chains near the Polynesian region of the South Pacific It is the vector of both the dengue virus and Wuchereria bancrofti, a filarial nematode worm causing lymphatic filariasis.[1]
Description
editSystematics
editAedes polynesiensis was first scientifically described in 1951 by the Australian entomologist Elizabeth Nesta (Pat) Marks [2], as part of a review of the Aedes Scutellaris group. The species belongs to the subgenus Stegomyia and is closely related to the Asian tiger mosquito, Aedes albopictus and more distantly to other medically important mosquitoes such as the yellow fever mosquito, Aedes aegypti. There is some contention over higher-level relationships and classification within the Aedes genus. In 2004 Stegomyia was elevated to Genus level but there has been considerable debate over the validity of this classification and most journal articles continue to refer to Aedes (Stegomyia) polynesiensis [3][4][5]
Appearance
editDistribution
editAedes polynesiensis is found on the islands of Austral Islands, Cook Islands, Ellice Islands, Fiji Islands, Hoorn Islands, Marquesas Islands, Pitcairn Island, Samoa Islands, Society Islands, Tokelau Islands, Tuamotu Archipelago.[1][6].
Colonisation of these islands by both mosquitoes and humans is thought to have occurred in an easterly direction and in some cases appears to be simultaneous, with the mosquitoes likely to have been transported by native canoes [7]. Dispersal within the island system led to geographically isolated populations, which is reflected in the genetic variation between islands. For example, the high level of divergence between mosquito populations from Fiji and Moorea (over 3000km apart) suggests that the process of speciation may have begun [8].
Life Cycle
editMosquito life cycles affect the ability of the blood feeding females to transmit disease, as most mosquito borne parasites and viruses need a period of extrinsic development within the mosquito prior to transmission to humans. Their breeding, feeding and habitat choices also influence population control methods that can be deployed against them. In the case of Aedes polynesiensis, larval insecticide control is problematic due to its wide variety of oviposition sites in both natural and artificial holes and containers; including tree holes, coconut shells, leaf axils, banana stumps, cacao pods and canoes [7][9]. The major larval habitats are the flooded burrows of land crabs [10], which provide protection against spraying of insecticide.
Following larval maturation and pupation, adults eclose and 60% of females are mated within 24hrs (Ali and Rozeboom, 1973). The lifespan of adult females in the wild is relatively short at around two weeks [11], and males will typically live for even less time. Females are primarily diurnal and biting tends to peak in the late afternoon and early morning[7][12]. The female will typically oviposit up to
During their lifecycle,
Lymphatic Filariasis
editAedes polynesiensis is a vector of the filarial nematode worm Wuchereria bancrofti, the primary cause of lymphatic filariasis in the South Pacific region. Infection is highly prevalent, although mostly asymptomatic. In 2000, 2.9m people in the Pacific Islands were infected with filarial worms; 38% of a population of only 7.6m (Burkot et al. 2002). The severity of illness scales with infection density, which accumulates over time with repeated bites from infected mosquitoes. Clinical manifestations can range from minor fever and swelling of the lymph nodes to the severe swelling seen in Bancroftian filariasis.
Microfilarial larvae at the L1 stage are taken up by the mosquito during blood feeding on infected human hosts, they mature in the thoracic muscles of the host and are transmitted as L3 larvae after an incubation period of around 14 days.
Major public health programmes
Dengue Fever
editAedes polynesiensis was first verified as a dengue vector in 1954 (Rosen), although it had previously been implicated by dengue outbreaks on some South Pacific islands in the absence of the primary dengue vector in the region, Aedes aegypti. It mostly transmits the virus in rural areas as opposed to the urban domain of Aedes aegypti (Maguire et al., 1971).
Vector Control
editNumerous vector control strategies have been employed in French Polynesia. Insecticide has only limited effectiveness because Aedes polynesiensis adults tend to rest indoors, and their wide variety of breeding grounds make it impossible to treat all areas.
- Release of larvivorous mosquito fish (Gambusia affinis and Poecilia reticulata). This was effective in some village habitats.
- Release of larvivorous copepods (Mesocyclops aspericornis). This proved ineffective in land crab burrows as they dry out periodically, which kills the copepods.
- Bacillus thuringiensis. This was added to land crab burrows but it was difficult to obtain a uniform distribution in the long burrows.
- Larvicidal baits. These were designed such that land crabs carried them back into their burrows, thus eliminating the need for burrow location and treatment by humans.
- Mechanical methods. These included blocking standing water with polystyrene beads to limit hatching and larval habitat, and house screening to prevent biting: These proved more efficient than biological control methods
The With all measures, it may not be necessary to permanently eradicate Aedes polynesiensis; the population must only be reduced below the transmission threshold for the lifespan of adult Wuchereria bancrofti in the human population, which is around 5 years.
References
edit- ^ a b "Polynesian tiger mosquito - Aedes polynesiensis".
- ^ "Encyclopaedia of Australian Science: Marks, Elizabeth Nesta (1918 - 2002)". Retrieved 31/01/2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ J. F. Reinert et al. (2004): Phylogeny and classification of Aedini (Diptera: Culicidae), based on morphological characters of all life stages. Zool J Linn Soc. 142: S. 289-368.
- ^ J. D. Edman (2005): Journal Policy on Names of Aedine Mosquito Genera and Subgenera. J Med Entomol 42(5): S. 511.
- ^ F. Schaffner & C. Aranda (2005): European SOVE – MOTAX group: Technical Note PDF 27 kB.
- ^ "WRBU: Aedes polynesiensis".
- ^ a b c John N Belkin (1962). The mosquitoes of the South Pacific: Diptera, Culicidae. University of California Press. Cite error: The named reference "Belkin1962" was defined multiple times with different content (see the help page).
- ^ Behbahani A, Dutton TJ, Davies N, Townson H, Sinkins SP (2005). "Population differentiation and Wolbachia phylogeny in mosquitoes of the Aedes scutellaris group" (PDF). Medical and Veterinary Entomology. 9 (1): 66–71. doi:10.1111/j.0269-283X.2005.00542.x. Retrieved 2011-01-31.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ "WRBU: Aedes polynesiensis".
- ^ Lardeux F, Rivière F, Séchan Y, Loncke S. "Control of the Aedes vectors of the dengue viruses and Wuchereria bancrofti: the French Polynesian experience". Annals of Tropical Medicine and Parasitology. 96 (2): 105–116. PMID 12625924.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Lardeux, F.; Cheffort, J. (2001). "Ambient temperature effects on the extrinsic incubation period ofWuchereria bancroftiinAedes polynesiensis: implications for filariasis transmission dynamics and distribution in French Polynesia". Medical and Veterinary Entomology. 15 (2): 167–176. doi:10.1046/j.0269-283x.2001.00305.x. ISSN 0269-283X.
- ^ "WRBU: Aedes polynesiensis".
Category:Aedes Category:Animals described in 1951
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