Some Mosquitoes Ignore DEET

The olfactory receptor neurons of some mosquitoes become less sensitive to the insect repellent after previous exposure.

By | February 21, 2013

WIKIMEDIA, US DEPT. OF HEALTH AND HUMAN SERVICESJust a few hours after their first exposure to the insect repellent DEET, the chemical no longer repels some mosquitoes because they can ignore its noxious smell, according to a report published yesterday (February 20) in PLOS ONE.

Developed by the United States military following its experience of jungle warfare during World War II, DEET (N,N-Diethyl-m-toluamide) is the most widely used active ingredient in insect repellents. It has been shown to be very effective, but recent studies have suggested that some Aedes aegypti mosquitoes—the species that spreads dengue and malaria—are not put off by its presence.

To understand how, researchers from the London School of Hygiene and Tropical Medicine attached electrodes to the antennas of female A. aegypti as the insects sought to feed on a human arm covered in DEET. Three hours after the chemical repelled the mosquitoes, some returning insects were less sensitive to the unpleasant smell. More importantly, the researchers saw that this insensitivity correlated with a decrease in the response of the insects’ olfactory receptor neurons.

“There is something about being exposed to the chemical that first time that changes their olfactory system—changes their sense of smell—and their ability to smell DEET, which makes it less effective,” coauthor James Logan told BBC News.

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Avatar of: Elmer

Elmer

Posts: 2

February 22, 2013

RE:  "Developed by the United States military following its experience of jungle warfare during World War II"

A small correction:  DEET was actually developed by the U. S. Dept. of Agriculture Insects Affecting Man and Animal laboratory in Orlando, FL (which was subsequently moved to the campus of the Univ. of FL in Gainesville.)  I know this becuase my father, Irwin H. Gilbert, was one of the principal entomologists on the development team.  For his efforts he received his salary, plus a small box of "OFF" from the SC Johnson Co., which has likely made billions from their use of DEET over the past 50+ years.

 

Avatar of: Dan Cossins

Dan Cossins

Posts: 237

February 22, 2013

Hi Elmer.

Thanks for your comment, and the extra information.

The US Environmental Protection Agency claims DEET was developed by the US military, as do various other reputable sources -- http://www.epa.gov/pesticides/factsheets/chemicals/deet.htm. But yes, as you mention, and to be more specific, it seems that the research was a collaborative effort between the Dept. of Defense and the Dept. of Agriculture, which together set up the lab of which you speak -- http://www.ars.usda.gov/Aboutus/aboutus.htm?modecode=66-15-10-20. Or perhaps it's more accurate to say the Dept. of Agriculture did the work on behalf of the military.

Anyway, thanks again for pointing that out.

Daniel Cossins
Associate editor

Avatar of: Elmer

Elmer

Posts: 2

February 22, 2013

Yes, Daniel, I think that your characterization of the situation is likely correct --  "the Dept. of Agriculture did the work on behalf of the military."  Furthermore, I believe that the military's role was one of providing funding and the WW II-era buildings in which the IAMA Laboratory was housed in Orlando. 

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