Wednesday, February 20, 2013

DEET Efficiency Less Effective the Second Time Around

Imagine a world without mosquitoes. It would be a world with less disease transferring insects and a world without mosquito repellent. Since eradicating a large and successful population of a specific insect would be nearly impossible due to its ecological backlash, with expectation to Janet Fang's theory, lets then talk about how we could continue to improve distancing our hot, human skin from the heat-seeking senses of mosquitoes.

DEET is a common, and highly regarded, mosquito repellent. DEET, (N,N-Diethyl-meta-toluamide), has been the subject of recent studies which has found that certain insects are unaffected by its presence. According to James Logan, Nina Stanczyk and colleagues, in the subject species A. aegypti, They found that three hours after pre-exposure the mosquitoes showed behavioral insensitivity... [and] pre-exposure to DEET has implications for the use of repellents and the ability of mosquitoes to overcome them.     

Logan and company, studied A. aegypti through three experiments dealing with the effect of DEET. Exp. 1 was the effect of DEET with a human arm (control variable), exp. 2 was with a nylon control on a heat source and exp. 3 was with a section of nylon tights with no arm present. Only female A. aegypti were tested and although they did not mention why they only tested females, it must be attributed to the females' ability to live longer than their male counter-parts; almost up to a month in captivity. With random probing and data collection, the results showed that it was not behavioral change that caused the ineffective repellency of DEET, ultimately it could be attributed to the mosquitoes natural response to have higher feeding success.

This case study is not discouraging the use of DEET but only analyzing the fact that certain mosquitoes has the ability to essentially ignore DEET once they have been previously exposed to it. Also the study does not know for how long this effect lasts. With studies like this, we can become closer to a place without too much mosquito interference.   

Poster by Tony Huynh (3)


  1. It would be interesting if future studies implified a life long resistance to Deet. We currently could be witnessing evolution at its finest.

  2. Don't you think that even if we find something to repel mosquitos, they will just evolve again to work against it? Evolution of arms race is at play here!

    Cynthia Bui (1)

  3. If mosquitoes can manage to ignore this common repellant, it will be interesting to see the implications for infectious diseases often spread by mosquitoes. Especially since right now the people being affected by these diseases are likely lower class and in third world countries, but if mosquito repellant becomes less effective it will most likely affect people with more money

    Hunter Alexander (1)

  4. This comment has been removed by the author.

  5. There is much controversy over the use of DEET with its toxic effects. It will be interesting to see how policy on it use towards mosquito repellant will change with our growing knowledge of its decreasing effectiveness. Evolution is constantly taking place though so ideally I hope we can find alternative repellents that can confuse the adaptability mechanisms of mosquitoes.

    Marshall Moini

  6. This comment has been removed by the author.

  7. It is worrisome that DEET is the first and most common choice of mosquito repellent being used. When used it is absorbed through the body and the most toxic effects can cause motor deficits and learning and memory dysfunction. Now that it has been proven that mosquitoes can become immune to it, I wonder if scientists will try another approach, perhaps ones that will last as long as DEET.

    Lindsey Dugas (1)

  8. Well I can say at least I do not use DEET and I feel at one point or another anything can be overcome. Its only a matter of time before a new formula for mosquito repellent is going to be needed because they will become immune to the affects by a simple mutation.

    Sunni-Lynn Farias (1)

  9. There really is no fool proof chemical that can be effective against a living organism for more than a few generations. It's the case with any repellant or even antibiotics. It's a shame it's still on the market, but hopefully there will be more progress soon. I can only imagine that the effectiveness decreases at a steady rate and will be a matter of time before it's just completely useless.