The widely
used insect repellent Deet appears to be losing its effectiveness against
mosquitoes.
Researchers from the London School of Hygiene and Tropical
Medicine say mosquitoes are first deterred by the substance, but then later
ignore it.
They say more research is needed to find alternatives to Deet,
which was first developed by the US military.
The research was carried out on Aedes aegypti, a species of
mosquito that spreads dengue and yellow fever.
The findings are published in the journal Plos One.
Dr James Logan from the London School of Hygiene and Tropical
Medicine, said: “The more we can understand about how repellents work and how
mosquitoes detect them, the better we can work out ways to get around the
problem when they do become resistant to repellents.”