Posted by: Footler PJ1 MAY 2013
Mosquitos of the species Aedes aegypti originated in Africa but now have a tropical and subtropical worldwide distribution. The insects spread dengue fever, chikungunya and yellow fever viruses. They are closely associated with humans and their dwellings and they have proved difficult to control or eliminate since their eggs can withstand desiccation for several months, even on the inner walls of containers. It is said that even if all larvae, pupae and adult
A aegypti are eliminated from a site the population could recover in two weeks as the eggs hatch following rainfall or the addition of water to the containers.
N,N-Diethyl-meta-toluamide, commonly known as DEET, is the active ingredient in many makes of insect repellent. It can be applied to the skin or clothing to provide protection against bites by ticks and insects that transmit disease. Although most insects are strongly repelled by the smell of DEET, studies have suggested that some flies and mosquitos may carry a genetic change in their odour receptors that makes them insensitive to the smell.
But new research from the London School of Hygiene and Tropical Medicine (LSHTM) found a response in A aegypti mosquitoes that appears to be based on short-term changes rather than genetic ones.The researchers found that some A aegypti mosquitos were able to ignore the smell of DEET for up to three hours after brief exposure to it. They believe the mosquitos are habituating to the repellent in a way that causes a decrease in the sensitivity of odour receptors in the mosquito’s antennae. The LSHTM confirms that DEET is a good repellent and it is still recommended for use in high risk areas. Meanwhile, research continues into the precise mechanism of this effect and what can be done to deal with it.