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Gene find aids mosquito battle
Culex mosquito: Major problem
The battle to control disease-spreading mosquitoes could be boosted after scientists found out how some strains beat insecticides.
The team of researchers from Montpellier in France found a genetic mutation which allows the mosquitoes to resist the effect of organophosphates - which are commonly used in efforts to control them.
Many millions of mosquito coils containing these chemicals are used each year.
If the gene discovery can produce organophosphates that work better against mosquitoes, this could improve the control of strains that spread diseases such as West Nile virus and filiariasis.
Our identification of this mutation may pave the way for designing new insecticides
Dr Mylene Weill, University of Montpellier
Most insecticide-based efforts to control the mosquitoes that carry malaria use a different chemical altogether.
However, the research could bear fruit if resistance to these chemicals increases in years to come.
Tropical pest
The Montpellier team, led by Dr Mylene Weill, found the mutation mainly in strains of the Culex mosquito.
While this is not as feared as the Anopheles strain, which carries the malaria parasite, it is the most common in tropical cities, and strains in temperate countries can carry West Nile Virus.
In recent years, main strains have shown pronounced resistance to organophosphates.
The pesticides work by disrupting a body chemical which helps keep the nervous system in insects from working smoothly.
West Nile Virus is carried by mosquitoes
The organophosphates bind to this key chemical and stop it doing its job - but the gene mutation prevents this from happening.
Dr Weill said: "We found the target for insecticides and we found the mutation that makes them resistant.
"Our identification of this mutation may pave the way for designing new insecticides and opens the way to new strategies for pest management."
Alternative
Dr Jo Lines, an expert in "vector biology" from the London School of Hygiene and Tropical Medicine, said that while Culex mosquitoes were a major problem, the finding would have less practical benefit against malarial mosquitoes.
He told BBC News Online: "Very few people use organophosphates to control Anopheles, especially in Africa, where 90% of malaria cases happen.
"The preferred insecticides are pyrethroids, which work in a completely different way."
However, he said that resistance to pyrethroids was increasing in some areas, so there might come a point at some time in the future where new insecticides might be required.
The research was published in the journal Nature.
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