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mosquito group
In 2007, a local Mosquito Group was formed at the NCZR to survey mosquitoes around the Neston and Parkgate area of Cheshire. The aim was to work out which species were biting people in the area and which may play a role in the transmission of disease to animals and humans.
This group was formed because, for many years, the residents of the Neston area of the Borough of Ellesmere Port and Neston have suffered from mosquito bites and their many complaints caused the Local Authority to look into the matter. The proximity of the tidal marsh at Parkgate and other coastal areas was believed to be the main source of the nuisance. The Environmental Protection Unit (EPU) of the Local Authority responded to the nuisance insects by spraying some of the salt marsh.
In 2006, the EPU carried out a survey of mosquitoes caught either in light traps or by local residents around their homes and gardens. Sixty one mosquitoes were caught in the 4 traps over the summer and 50 of these were Aedes detritus, the salt marsh mosquito. Twenty three mosquitoes were sent in by residents in September and the majority of these were non-marsh mosquitoes, especially Culex pipiens. The EPU believed that this species was responsible for complaints of biting nuisance in September 2006 and suggested that they were breeding in sites such as ponds and spare water receptacles around the affected houses, rather than in the marshlands.
The EPU decided that a more extensive survey was needed and this was when NCZR became involved. The Mosquito Group planned and carried out a survey in 2007. The mosquitoes were caught using CDC light traps, BG traps and by members of staff at the Leahurst campus of the University of Liverpool bringing in any they found. The mosquitoes were identified by Professors Mike Service and Michael Clarkson, both from the University of Liverpool. The keys used to distinguish between species were ones devised by Mike Service.
Staff members caught 250 mosquitoes in their homes and gardens in the Neston area and a further 150 mosquitoes were caught in traps. The traps were usually emptied only weekly and the specimens were often damaged, whereas the individuals collected by staff were in excellent condition and were, therefore, easy to identify.
The two methods, however, produced similar results, in that approximately two-thirds of the mosquitoes found were Culex pipiens group, almost one-third were Aedes detritus with the remainder being Culiseta annulata.
The survey method involving colleagues was very effective and can be recommended for those who are part of a community on a circular email system. Since the members lived over a wide area of the surrounding region, geographical distribution was easy to obtain. It was essential to identify the specimens and communicate the results back to the collectors rapidly to maintain interest. Information regarding biting features and the main breeding sites and other general facts helped to involve the collectors further.
Since Culex pipiens bite only birds, it is clear that humans in this area are being bitten mainly by Aedes detritus.
A number of scientific projects has arisen from this survey. One of these is a study on molecular identification of the members of the Cx. pipiens group, including Cx. torrentium, another bird-biting species, and Cx. molestus, the latter being a species that bites humans. Since members of this group of mosquitoes are involved in the transmission of West Nile virus in humans in the USA, this study would provide important information if the infection became established in Britain. A large number of Cx. pipiens group mosquitoes have been preserved to identify once the molecular techniques have been validated.
A database is being set up by Dr Christian Setzkorn (NCZR) which will give a more precise location of all the mosquitoes collected (see map) and could easily be extended to any area of Britain, Europe or even the world! In this regard, any specimens of mosquitoes collected in Britain would be welcomed for identification.
The group is also assisiting members of the Epidemiology Group at Liverpool University with information on mosquito vectors of animal and human diseases.
A short powerpoint presentation on this work was given to AVTRW recently and can be seen here.
