What Makes DEET So Effective Against Mosquitoes?

With summer nearly upon us in the Northern Hemisphere, many people will be considering hiking and camping trips that will bring them into contact with those dreaded harbingers of warm weather – mosquitoes. Thankfully, numerous insect repellents can keep them at bay. Many of these products rely on the active ingredient DEET, which has been used since the 1940s, despite scientists not fully understanding why or how it works.

In 2019, researchers led by neurogeneticist Emily Dennis, then a Ph.D. student at Rockefeller University, solved an important piece of the puzzle – how mosquitoes perceive DEET through physical contact. By using special glue that disabled taste receptors on mosquito legs, Dennis and her colleagues discovered that mosquitoes “taste” DEET through tongue-like cells on their six feet, rather than with their mouthparts.

Using her own arm as “bait,” Dennis found that if a mosquito lands on a patch of human skin covered in DEET, it will fly away because it doesn’t like how DEET feels on its legs. In the experiment, when their legs had been painted with glue, the feel of DEET on their mouthparts alone was not enough to deter mosquitoes from sticking around and piercing the skin.

By uncovering that mosquitoes taste DEET through their legs – and not their mouthparts – this research could be useful in future efforts to design longer-lasting (and possibly less oily) insect repellents specifically focused on the leg taste receptors.

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