Mosquitos and DEET

[Dickerman]

I'd like to comment on the column about mosquitoes and blood type: http://www.straightdope.com/columns/...ood-types-plus

The fourth paragraph says:

"How do mosquitoes know about chemicals on your skin? Smell, probably. Mosquito repellents ranging from garlic to DEET seem to work by blocking their sense of smell."

This is what I've always heard, but it appears as though there is reason to believe that this is not the case, according to recent research: http://www.sciencedaily.com/releases...0818183942.htm

According to the research, mosquitoes simply don't like the smell of DEET.

[Dickerman]

Here's a link to a PDF of the paper: http://entomology.ucdavis.edu/news/0805312105.full.pdf

[Fear Itself]

I wonder why they don't like the smell of DEET. It's not a learned behavior, so it must be hard wired, but since DEET hasn't been around long enough to affect evolution, it must smell like something else that they developed an aversion to as a species. Perhaps some prey whose blood doesn't agree with them?

[Dickerman]

Could be. In a commentary to the paper that was published in the same journal, is this:

Therefore, it is possible that the ORNs responding to DEET have evolved to respond to naturally occurring compounds that have repellent properties conveying ecological benefit. Indeed, Syed and Leal show that certain plant-derived terpenoids (thujone, eucalyptol, and linalool) cause electrophysiological responses at concentrations lower by an order of magnitude. Thus it would appear that DEET, with its relatively low volatility, can remain on human skin for some time and release slowly, by evaporation, to stimulate the ORNs responding to natural essential oil repellent components, to which the DEET receptor (possibly as a consequence of the unnatural origin DEET) is an order of magnitude less sensitive.

[Deeg]

Interesting. I always thought DEET poisoned the little bastards. On occasion I have gleefully sprayed DEET on clouds of mosquitoes with the misconception that I was killing them; now I'm disappointed. I wonder if they'll be able to concoct a less toxic (to humans) version of DEET.

[Dickerman]

Originally Posted by Deeg

I wonder if they'll be able to concoct a less toxic (to humans) version of DEET.

Someone might. FWIW, I believe the toxicity of DEET is often far overblown, and without good scientific evidence. For example, this New England Journal of Medicine publication (85kB PDF): http://www.bouldercounty.org/health/...EJMArticle.pdf

includes this:

Despite the substantial attention paid by the lay press every year to the safety of DEET, this repellent has been subjected to more scientific and toxicologic
scrutiny than any other repellent substance. The extensive accumulated toxicologic data on DEET have been reviewed elsewhere. DEET has a remarkable safety profile after 40 years of use and nearly 8 billion human applications. Fewer than 50 cases of serious toxic effects have been documented in the medical literature since 1960, and three quarters of them resolved without sequelae.

(I removed the reference numbers for readability.)

I know there are those who swear that they have various negative reactions to DEET, but the best scientific evidence does not appear to support anything but an extremely low level of toxicity.

[Fear Itself]

Kudos to shannybonanny, who appears to have originated the phrase "addictive as caramel-covered crack" that Cecil credited to the SDMB in this column.

[MOIDALIZE]

Judging by the accompanying cartoon, I suspect they're attracted to gigantic boobs as well.

[DSYoungEsq]

More recent information on the issue of why they bite you.

[Win.Pollard]

The great majority of Native Americans are type O. Could type O blood be the natural diet of American mosquitoes?