Neuroscientists at Northwestern University have made an amazing discovery about catnip, it repels mosquitoes and other insects. The active component of catnip (Nepeta catoria) is nepetalactone which stimulates a neuroreceptor called TRPA1. TRPA1 is found in most animals from insects to humans, and transmits pain sensation to the brain. TRPA1 can also be triggered by hot, cold, and irritants.
The interesting thing is that when applied to humans as a repellant it does not trigger a pain response in the human, nor does it trigger pain in felines. In felines it triggers a different receptor involved in pleasure sensation.
Work is underway to find an effective way to use nepetalactone in an easily applied skin vehicle to provide a non-DEET alternative for summer misery.
The frequent rains this summer have led to a bumper crop of hungry mosquitoes. Although many repellants are available, the most effective compound seems to be DEET. It works because its scent is extremely irritating to biting insects, such as mosquitoes and fleas. Unfortunately, DEET is fairly allergenic with upwards of 30 percent of individuals developing a rash after repeated use. The types of rash seen are contact dermatitis (looks like poison ivy), eczema and urticaria (hives). The fact that DEET is a somewhat irritating chemical, and that it is repeatedly applied to the same skin areas, leads to the development of allergy.
Luckily, a new effective repellant has recently been developed – picordin. It, too, works because its scent dissuades biting insects; however, unlike DEET, it is not irritating or allergenic to the skin. Also, it is tolerated even in individuals already allergic to DEET.