A study by British researchers has revealed that certain mosquitoes have become accustomed to DEET – one of the molecules most commonly used as a repellent against insects. This research proves to be a new concern for the fight against the spread of diseases such as dengue or chikungunya.
DEET, or N, N-diethyl-meta-toluamide, is one of the most widely used component in insect repellents This was developed by the U.S Army during World War II while fighting in the jungle. The DEET has an unclear mode of operation, but in fact, it affects the localization of targets by the mosquitoes.
Insects Are Less Sensitive
Conversely, in a study published in the periodical, PLoS ONE, in February 2013, a team of researchers from the London School of Hygiene & Tropical Medicine has demonstrated that a type of mosquito, Aedes Aegyptis, loses its sensitivity to the repellent odor.
To understand this mechanism, the scientists have proposed to tender an arm covered with DEET to the insects. In a first instance, the insects got repelled by the odor. But a few hours later, while the arm was put forward to the insects a second time, the DEET proved to be less deterrent.
Modification of the olfactory system
Dr. James Logan, one of the authors of the study says “We discovered that mosquitoes were not as sensitive to the product as before. Their olfactory system has changed upon a first exposure to the DEET.” Indeed, this is what happens in the case of a smell even if the human olfactory system is very different from that of the mosquitoes.
A major challenge
After this initial observation, the team of British researchers will tackle the study of this phenomenon on other types of mosquitoes, such as those that transmit malaria. For Dr. James Logan, “the findings should not prevent people from using DEET in high-risk areas, but may help scientists in trying to find new versions of repellents that could be effective.”
The stakes are high since dengue, as well as, chikungunya are already present in Asian and tropical countries. And these diseases could proliferate to Europe in the coming years.