Recently, a team of johns Hopkins university researchers reported the mechanism of mosquito response to the common repellent DEET in the journal Contemporary Biology.
The researchers say DEET can "catch" human odors, hiding human odors like an "invisible cloak" and preventing them from coming into contact with mosquitoes. They found that when combined with DEET, the number of human odor molecules in the air decreased by 20 percent.
DEET, or DEET for short, was once used as a pesticide, and spraying it on skin or clothing can avoid insect and mosquito bites. Many of the mosquito repellent products sold on the market contain DEET, but the mechanism of action of DEET was not previously known.
First author, Ali Aphre, a postdoc at johns Hopkins University School of Medicine, said, "We found that DEET interacts with chemicals on our skin and masks them, rather than directly repellent mosquitoes." This will help us develop new mosquito repellents with the same effect."
The research team used genetic engineering techniques to breed a variant of Anopheles mosquitoes, also known as TheOptera malariae mosquitoes, which are distributed around the world. In the experiment, when the researchers spewed out an odor that Anopheles could detect, such as spraying the chemicals that make up the odor of human skin onto the mosquito's antennae, neurons with fluorescent particles on the mosquito's antennae were lit up, indicating that the mosquito's nose detected the signal.
But when the researchers sprayed the odor of DEET separately onto the mosquito's antennae, the fluorescent particles in the mosquito's neurons didn't light up. Christopher Porter, author of the paper and an associate professor at Johns Hopkins University, said, "This suggests that mosquitoes cannot directly smell the chemical."
It is worth noting that when the human odor is mixed with deworming amine, simulating the effect of applying insect repellent to the skin, the ability of mosquito neurons to respond to the mixture is greatly weakened, with only 15% of the ability to respond to human odors.
To explain this, the researchers measured the number of odor molecules in the air that reach the mosquitoes' antennae. They found that when combined with DEET, the number of human odor molecules in the air decreased by 20 percent.
Ali Aphrofer said, "We think THAT DEET can catch human odors and prevent them from coming into contact with mosquitoes"
The research team has yet to study the effects of DEET on other species of mosquitoes and says they plan to address the issue in future experiments.