Last month I wrote a post about Nootkatone as an alternative to the mosquito repellent DEET. New research into mosquito sense of smell has identified a new type of insect repellent, called VUAA1, that repels not only mosquitoes but also other nuisance insects.
VUAA1 was identified by a group led by Laurence Zwiebel at Vanderbilt University and the research published in the Journal, PNAS. Odors are caused by chemicals present in the air. Odor detection in most animals involves an olfactory receptor or “OR”. When chemicals in the air enter our nose and interact with an olfactory receptor, we “smell” the chemical. In humans, multiple types of OR are responsible for our ability to differentiate among chemicals and that is why different chemicals produce different odors. For example, the chemicals in the fragrance emanating from a rose differ from the chemicals emanating from a pile of manure. The chemicals from the rose interact with different odor receptors than the chemicals from the manure pile. That is why a rose smells different from a pile of manure.
The odor receptors of insects are a bit different. Insect odor receptors “ORs” require a cofactor or “Orco” in order to detect an odor. When an insect OR interacts with an odorant chemical, it will form a complex with the Orco. The Vanderbilt team tested a group of over 118,000 chemicals for ability to bind to mosquito ORs. One chemical in the screen, VUAA1, caused multiple types of ORs to bind to Orcos even though no odorant molecule was present. The net effect of the VUAA1 on mosquitoes is to activate all odor receptors. Imagine suddenly sensing every possible odor at the same time. The poor mosquitoes are confused and rendered incapable of detecting important odors.
Mosquitoes use odors such as carbon dioxide and lactic acid to find hosts (people) to bite. If their sense of smell is disrupted, then their ability to find people to bite may be disrupted. If mosquitoes can be prevented from biting, it would prevent transmission of important mosquito vectored diseases.
The properties of VUAA1 are not characterized. It will be important to determine what, if any effects VUAA1 might have on humans if applied on the skin as an insect repellent. Commercialization of this new discovery may be years away. However, as mosquito season erupts all around (I smacked a couple as I typed this post), it is nice to have new hopes for the future.