There’s been a lot of reporting about new research about the insect repellent DEET this week. Unfortunately, some of the media didn’t quite get it right. Headlines like this one were common…and completely wrong.
The media coverage left a lot of people confused about DEET, and if it still worked. The results of the research were a lot more nuanced than “DEET suddenly stopped working so we are all screwed.”
Here is what the average person being bitten by mosquitoes needs to know, condensed:
DEET still works fine. It’s still one of the best insect repellents out there. We know a way it might become less effective now, as demonstrated in the laboratory.
The un-condensed version:
DEET is one of our oldest and best insect repellents. It’s universally acknowledged as the best repellent around, and has broad activity against several types of biting flies and ticks. This is why a problem with DEET is big news–it’s invaluable in preventing transmission of several different diseases.
Amazingly, scientists are just beginning to understand how DEET works, even though it’s been in widespread use for 50 years. We know it stops ticks and mosquitoes from biting, but the exact mechanism of how that happens is still not clear. Does it make us ‘invisible‘ by blocking mosquitoes from smelling? Does it smell horrible to biters? It’s still not settled science yet.
That’s important to know, since if we know how something works, we can copy it and try to make new and better controls. There is always a concern with evolution of resistance in insects–they are commonly used to study genetics and mutations for a reason. Insects breed fast, and they breed often–which means that small genetic changes, if they are helpful at keeping a bug alive and having sex, can spread quickly through a population.
Resistance to DEET, our most powerful and broad spectrum insect repellent, would be a very bad thing. And so it makes sense that entomologists interested in human health would be studying how DEET works.
Evidence of genetic resistance to DEET in mosquitoes has actually been around since 1994. In 2010, researchers found that they could increase the frequency of a gene that made mosquitoes ignore DEET to 50% in a couple of generations. That’s alarming, but that was in a laboratory-bred colony.
‘Laboratory-Bred’ is an important distinction for both that study and the recent one. Mosquitoes in a cage have only one source of food (often the hapless graduate student that is rearing them). They can’t fly off and look for other people or animals to bite. It also means that their sexual choices are limited to other mozzies in the cage, so resistance can evolve more quickly that it would out in the wild where they have a wider choice of hookups.
Scientists use work in the lab to model the real world. It helps us understand how organisms grow, change, and respond to their environment. That doesn’t mean that it’s a firm prediction of what will happen out in the larger world, especially with a group as diverse and wily as mosquitoes. That’s why I think headlines like the one at the top are irresponsible, and mangling the message of the research.
You can see an interview with one of the researchers here; note she is careful to repeat that we should not discard DEET wholesale on the results of this research!
“What this work indicates is that there may potentially at some point in the future be some problems with the repellents that we have, that we need to be aware of in advance. Possibly we can use this information to alter the repellent DEET to make it more effective, it may also help us in finding new repellents because we will know if [mosquitoes] are able to overcome certain things……Even though repellents are working fantastically at the moment, what this tells us is maybe how to prevent problems cropping up, and how to alter things for the future to make them more effective.” [emphasis mine]
- CDC list of recommended insect repellents
- Mosquito repellent clothing (uses a different chemical than DEET)
Articles referenced in this post:
- Stanczyk N.M., Brookfield J.F.Y., Field L.M., Logan J.G. & Vontas J. (2013). Aedes aegypti Mosquitoes Exhibit Decreased Repellency by DEET following Previous Exposure, PLoS ONE, 8 (2) e54438. DOI: 10.1371/journal.pone.0054438.t001
- Ditzen M., Pellegrino M. & Vosshall L.B. (2008). Insect Odorant Receptors Are Molecular Targets of the Insect Repellent DEET, Science, 319 (5871) 1838-1842. DOI: 10.1126/science.1153121
- Jaramillo Ramirez G.I., Logan J.G., Loza-Reyes E., Stashenko E., Moores G.D. & Vontas J. (2012). Repellents Inhibit P450 Enzymes in Stegomyia (Aedes) aegypti, PLoS ONE, 7 (11) e48698. DOI: 10.1371/journal.pone.0048698.t003
- Rutledge L.C., Gupta R.K., Piper G.N. & Lowe C.A. Studies on the inheritance of repellent tolerances in Aedes aegypti., Journal of the American Mosquito Control Association, PMID: 8014634
- Stanczyk N.M., Brookfield J.F.Y., Ignell R., Logan J.G. & Field L.M. (2010). Behavioral insensitivity to DEET in Aedes aegypti is a genetically determined trait residing in changes in sensillum function, Proceedings of the National Academy of Sciences, 107 (19) 8575-8580. DOI: 10.1073/pnas.1001313107
One question I’m often asked is why this Bug Blog is also listed as a skeptical blog. The connection between skepticism and bugology isn’t always immediately apparent, I guess, but it seems quite logical to me.
There are many, many bogus devices that claim to repel insects, and I think it’s important to name names. There are far too few convictions for fraud in the insect repellent business. I’ve called out some of these in the past; the iPhone app that supposedly repels mosquitoes, for example, or the Bug Banisher that releases an imaginary “negative ion field.” It seems sometimes like as fast as I can name and shame, there are new and even more silly devices on the market.
Case in Point: shoo!TAG™ insect repelling credit cards
Shoo!tags “utilize an understanding of nature’s energetic principles in combination with physics and quantum physics, as well as advanced computer software”. What exactly does that mean? Well, just as the magnetic strip on a credit card is encoded with specific information, there is a three dimensional electromagnetic field embedded in the Shoo!tag. Shoo!tag uses the energy field that a animal emits, then adds other frequencies that repel insects. Although they don’t actually kill insect pests, these frequency barriers disturb and confuse the pests. Essentially, the pests don’t want to be anywhere near the Shoo!tag wearer.
By now, your BS antennae should be quivering. Frankly, anytime someone uses the word “Quantum”, you should be suspicious. Or when something with no power source claims to generate an electromagnetic field. Reading the disclaimers about why the tags might not work as promised can be rather hilarious:
“Possible reasons shoo!TAG™ may not be working: The tag is near or has been near a strong frequency (cell phone towers, electric transformers, fault lines, electronic home security systems, etc.) which interferes with the coding in the magnetic strip.”
Ah! That’s why it didn’t work–I live in the US where those things are rather difficult to avoid. According to recent press, shoo!TAG™ is a >$600,000 dollar business. That’s probably because each arthropod needs its own tag. You can’t just buy one; you need a chip for:
- Mosquitoes ($19.95)
- No-see-ums ($19.95)
- Chiggers ($19.95)
- Ticks ($19.95)
- Flies (species not specified, but presumably not mosquitoes or no-see-ums, which are, in fact, flies) $19.95
For full “protection” in the woods, that’s about $100, although they do have a Mosquito-Chigger-Tick pack for just $39.95. Each tag lasts about 4 months, unless you have an especially vigorous energy field. Oh, and you have to outfit your pets too–the tags above are (literally) dog tags.
That’s a lot of money, and it’s also a lot of risk. You can DIE from diseases transmitted by ticks and mosquitoes. It’s really not something that lends itself to self-experimentation.
I was all ready to go postal about this when I realized that someone had already done that work for me. Major props go to Anaglyph for masterful work in exposing just how shabby Shoo!TAG’s claims for their products are. He’s been writing about this since 2009; you can find an archive of all his Shoo!TAG posts here. His series of posts is an excellent example of how one person with a blog can make a difference.
He’s done a great job explaining why the these devices can’t possibly work without massive violations of physics as we know it. Since their claims of magical electromagnetic field creation are bogus, I don’t think I need to bother explaining why the energy field these tags don’t generate….. would not repel insects anyway.
I liked Anaglyph’s recent letter to Shoo!Fly’s CEO so much I’ll reproduce a large part of it here:
My concerns with ShooTag are many: firstly, you are taking advantage of people by selling them something which, although it is not supported by any known science, you continually attempt to frame in a scientific context. In other words, you use ‘sciencey’ sounding terms to attempt to make ShooTag sound credible.
For a start, you offer up ideas such as the ‘trivector’ mechanism, ‘energy’ fields and the vague concept of biological ‘frequencies’ as if they are proper scientifically supported notions, which they are not. At best these things are speculative, but mostly they are just plain nonsense. In addition to presenting pseudoscience as science, you imply that the mechanism of ShooTag is somehow supported by actual scientific concepts of which you plainly have little comprehension, such as quantum physics, fractal mathematics and Schumann Waves.
All these things are meaningless in relation to your product, at least in any way that have attempted to demonstrate so far. You also use the names of scientists like Albert Einstein and Geoffrey West, whose work you clearly don’t understand, in a manner that suggests that their theories offer support of your own speculations (which they most certainly don’t). This is misleading and irresponsible.
In addition to all this, you regularly refer to scientific ‘experiments’ which you say demonstrate not only that your product works, but that it works extraordinarily well. The experiments you reference either show nothing of the sort (such as your ‘Texas A&M Field Trials’ which were scientifically ridiculous), or don’t have substantiation of any kind (like the supposed ‘European Trials’ which you have mentioned on several occasions on the web but from which you have never provided any data whatsoever, or the supposed supporting video from ‘the Japanese Ministry of Health’ which you boasted about on your site but which never materialised there for anyone to see). You also continue to heavily infer that credible organizations are involved with your product (Texas A&M University, Texas State University, the Japanese Ministry of Health, the Finnish Olympic Team) when it is clear that no such endorsements have been made or were intended (as is quite evident from my conversations with the administration at Texas State University, and their requirement that you remove any such TSU endorsements from your site). Excuse me for saying so, but responsible companies with legitimate products do not undertake this kind of deceptive behaviour.
In short, you want everyone, particularly your prospective customers, to think that ShooTag is validated by science and approved by authoritative institutions, yet you have nothing to support your claims other than self-generated hyperbole and subjective customer testimonials. No science.
Oh, SNAP. That. Was. Awesome.
And there’s more–read the full letter for a masterful spanking of a woo peddler.
Why am I telling you about this in a rather longish post? I discovered that Shoo!TAG donated $30,000 worth of their “units” to a children’s bible camp in Zambia in April 2011. And they sent tags to Haiti after the earthquake (through a bible missionary chiropractic group. Talk about insult to injury!). Shoo!TAG issued press releases about all this, and I strongly suspect they also took a nice tax write-off on their used (not even new!) plastic bits as well.
What they are doing is just….vile. I can’t think of a more descriptive word. Sure, these tags seem like innocuous pieces of crap that will part gullible people from their money. It’s all fun and games until someone dies of malaria, yellow fever, or lyme disease, because they thought hanging a credit card around their neck would protect them.
The problem is, to whom do you report people selling this kind of woo to? There has to be a way to make an obviously fake device like this go away.
The Federal Trade Commission has prosecuted people selling deceptive devices before, but they sure don’t make reporting easy. Their Complaint Assistant is mostly focused on online fraud and identity theft. The Consumer Product Safety Commission is a possibility, but again, shoo!TAG™doesn’t really fit into any of their categories.
When you look at the FDA Guide to reporting problems, the categories for human health problems don’t quite fit. It’s easier to report shoo!TAGs for veterinary use than for people. Since heartworms,tick paralysis, and equine encephalitis are just some of what users of these tags put their pets at risk of catching, that’s not entirely a bad thing.
Minimum risk pesticides are a special class of pesticides that are not subject to federal registration requirements because their ingredients, both active and inert, are demonstrably safe for the intended use.
Since shoo!TAG™ is plastic and don’t do anything, I’d say they’re inert, alright. But “minimum risk”? It turns out there is some special language about that exemption:
“EPA…concluded that public health products must be supported by evidence that they are effective against the target pest.”
And here is where I go all PollyAnna on your asses.
I believe that social media has the potential to truly change the way the world works.
One of the things bloggers can do with their bully pulpits—no matter how modest– is fact-check claims that businesses (or politicians!) make, and call readers to action. While blogs and Twitter and Facebook can disrupt our lives, they also make it possible for people to draw attention to things that just aren’t right.
As blog readers, you can respond and spread that fact-checking in ways that warm the cockles of my misanthropic little heart. Let’s harness our community power. Who knows someone at the EPA enforcement division? Minions, mobilize!!
Related Bug Posts:
Best of all, I am joined on this episode of Skeptically Speaking by anthropologist Greg Laden, who talks about entomophagy (bug eating).
My part of the interview starts with a discussion of using a pseudonym online, and why I think scientists need them. Then we have a fun chat about treehoppers, bees, and fake mosquito repellent devices. Bonus moment of embarrassment: I try to be relevant to a Canadian audience by comparing native pollinators to Wayne Gretzky.
Here are links to my posts about some of the topics from this episode:
When I was looking up something for last week’s rant, I discovered this map, which shows the progress that has been made in fighting Malaria. Sometimes, I think it’s easy to forget that while a lot remains to be done, there also has been a lot of success. The top map (a) is the extent of malaria in 1900, reconstructed from historic records; the bottom map (b) is the extent of malaria in 2007.
Of course, because this is from a scientific paper, there has to be jargon. To translate: the different colors relate to the level of infection in the general population (PR, or Parasite rate). ”Endemic” means that the infection is maintained in a community at a more or less steady state.
- Epidemic/Unstable means that infections break out periodically in these regions
- Hypoendemic: less than 10% of the population is infected with malaria
- Mesoendemic: between 10% and <50% is infected with malaria
- Hyperendemic: Between 50% and75% is infected with malaria
- Holoendemic: over 75% of the population is infected with malaria
In all but 2% of areas around the globe, malaria infections have declined since the rates before 1968. This graph helps visually show where the difficult to control hot spots are, and also the range of different countries and environments in which malaria can occur.
Full Citation of the paper that is the source of this graphic:
Gething, P., Smith, D., Patil, A., Tatem, A., Snow, R., & Hay, S. (2010). Climate change and the global malaria recession. Nature, 465 (7296), 342-345 DOI: 10.1038/nature09098
I read a lot of strange stuff on the internet. I mean, I’ve covered Extraterrestrial Cows and Mail-order public lice. But I really don’t expect to run into silly conspiracy stuff in Forbes, of all places.
In an article entitled “The Black Death: Longing for the Good Old Days,” James Taylor ties together global warming denialism, DDT boosterism, Edgar Allen Poe, and the Black Death (i.e. Bubonic Plague) to make…a really big pile of something that steams.
He suggests that everything was hunky dory when the climate was hot, but when things got cold–OMGPLAGUE:
“What brought about the Black Death? A thousand years ago, Europe was experiencing a golden age. The fair climate of the Medieval Warm Period, with temperatures similar to or warmer than today’s climate, stimulated bountiful crop production, supported unprecedented population growth,….
Longer winters and cooler, shorter summers decimated crop production throughout Europe. The rains that fell were cold, persistent, and slow to dry up. Famine and plague, which had largely disappeared during the Medieval Warm Period, became the norm rather than the exception. And by 1350, the grim, cold climate brought about the dreaded Black Death.”
He goes on from this to imply that environmentalists want to curb global warming in order to kill us all by bringing back the Black Death. Oh, and malaria, but we’ll get to that part later.
I actually have spent a lot of time over the years researching Bubonic plague, and the 14th century European “Black Death” in particular. I have never read of climate being implicated as a cause for the European plagues. Never.
I would also like to point out that the Little Ice Age actually occurred several hundred years AFTER the period of the bubonic plague outbreaks in Europe. A recent review paper listed the start date around 1570. So, the dots he’s trying to connect, in addition to being unrelated factually, are also unrelated chronologically.
The more interesting theories about why the Black Death was so devastating to Medieval Europe center on increasing urbanization and commerce. In order to have a massive epidemic, you need populations of potential victims to be concentrated. If you get the plague in the middle of nowhere, you will die horribly…and that’s it. There is no one to transmit the plague TO.
On the other hand, if you have concentrations of people in cities and towns; and you have movement of both people and animals between cities and towns, then you have a situation that is ripe for an outbreak. If you add in poor sanitation, it’s a dream for a disease bacterium.
There is a well-documented timeline of outbreaks moving from Asia over to Italy, and then up through Europe. Rats in grain and rats in ships moving from place to place for commerce were probably the primary movers of the disease. (In case you’ve forgotten, fleas are the vector of plague between humans and other animals. In other words, fleas transmit the plague bacteria from infected people/rats to new victims.)
Mr. Taylor is a lawyer working for the Heartland Institute, which advocates for unregulated trade (and also says that cigarettes are harmless). Somehow he seems to have missed the obvious connection between free markets and plague. Hmm.
So, what else? Oh, the Malaria–right. From the article:
“Malaria was becoming a distant memory 50 years ago, but the World Health Organization now reports that over 200 million people contract the disease each year and nearly one million people die from the disease each year. A single, small application of DDT to the inside walls of a hut – in which malarial mosquitoes most frequently infect their victims – will keep malarial mosquitoes at bay for months, but environmental activists have forbidden this chemical infringement on The Natural Condition.”
Let’s start with that first sentence. 50 years ago, Malaria was becoming a memory for the US and Europe; they launched very successful campaigns to control mosquitoes. Malaria eradication was not, however, successful in Africa, Asia, or Latin America. In fact, some areas never were part of any Malarial control campaign. It’s certainly correct to say that too many people die of malaria each year; but it is not correct to say that more die now than in the past. If you look at WHO data for most regions, there is a clear downward trend. Global control of malaria has been slowed by resistance to treatment drugs, as well as mosquito resistance to DDT.
Which brings us to his next claim. In his second sentence, he claims that DDT can be applied to the walls of a “hut” and provide protection from malarial mosquitoes. News flash–not everyone lives in huts–your imperialism is showing. But, hey, let’s run with it.
This is an incorrect statement for a variety of reasons. Indoor Residential Spraying (IRS) is actually not a preferred methodology for the World Health Organization Malaria group; they specifically recommend against using the same chemical year after year. Increased resistance to pesticides is strongly tied to indoor sprays in the report I linked. A quote: ”it is unlikely that universal vector control coverage can be achieved in Africa by IRS alone.”
Taylor’s pollyanna approach ignores the the reality of DDT and malaria in the world today. A hundred countries currently have a malaria problem. It is patently absurd to think that one single chemical (and methodology) can solve a problem that is global in scope.
There isn’t only ONE species of malaria mosquito–there are dozens (And they don’t all bite you when you are inside). There is not just ONE kind of ecosystem in which people and malaria interact. Designing a malaria control methodology has to take into account the political, environmental, and socio-economic situation of a particular community. What, if any, data do we have on the resistance of the mosquitoes to insecticides? It is not a one-size-fits-all problem with one solution.
His last sentence is also untrue. DDT is part of current WHO treatment guidelines. It is not “forbidden”. But DDT is only one piece of a huge, huge complicated problem, and over-reliance on it can actually make things worse by leading to greater insecticide resistance.
What I want to know now is–Why did Forbes let this douche write an article full of BS that was VERIFIABLY FALSE? And what are they going to do about it?
I usually like Lifehacker, but in this case, FAIL. Here’s a story they ran 2 weeks ago:
Bounce Fabric Softener Keeps Mosquitoes and Gnats Away
Some people have sworn by the power of Bounce dryer sheets—and specifically Bounce, too—to keep mosquitoes away from them, and gnats out of their garden. Now scientists have proven the power of fluffy white sheets as an insect repellent.
Lifehacker wasn’t the only media group that picked up on this story; and pretty much all of them made the same mistake.
When you look at the actual research paper, what you see is that some of what was reported was correct. There actually WAS a paper that examined the repellency of Bounce dryer sheets to insects.
Raymond A. Cloyd, et al. (2010). Bounce® Fabric Softener Dryer Sheets Repel Fungus Gnat, Bradysia sp. nr. coprophila (Diptera: Sciaridae), Adults.
HortScience, 45, 1830-1833
There is a very large difference between a fungus gnat and a mosquito. That’s rather like reporting that the care and feeding of cats and humans are interchangeable. Since, you know, we’re all mammals, right?
Let’s start with what a fungus gnat is, and when you’d be likely to encounter them.
Basically, fungus gnats don’t bite. They just annoy. They’re likely to be the tiny things flitting around the soil of your potted plants. They can be a commercial pest in greenhouses, but generally they are just a nuisance. They breed in moist soil and nibble on roots.
I think everyone knows what mosquitoes are–a biting fly that can carry major human diseases. They breed in water and adult females require a blood meal from a host to reproduce.
Not. The. Same.
This is an important difference, and it is a difference that has human health implications. If you go out in an area where there are disease-carrying mosquitoes with just a pocket full of dryer sheets as your protection, you are taking a risk with your health.
Media make mistakes covering science news all the time–but in this case, it’s a taxonomic mistake that could literally cost someone their life. (Ok, I’m overstating it a bit. But, in THEORY, I’m right.)
Now that I’ve impressed upon you what’s at stake, let’s look at the actual experiment, shall we?
The authors tested the repellency of the dryer sheets in a very controlled situation, and were successful at reducing the number of fungus gnats in test chambers containing a dryer sheet. At the end of their paper there is this caveat:
However, there are still important issues that need to be resolved, including the residual effects (based on age of dryer sheets) and effective distance of repellency, response in a no-choice situation (if dryer sheets are placed into each petri dish), impact on fungus gnat larval populations, and ultimately plant damage.
Now, every scientific paper ends this way. Here’s what we did, and here’s how it’s uncovered a whole host of new questions for us to answer! Continued employment, yay!
What I, as a gardener, would draw from this experiment is that it certainly couldn’t hurt to put a Bounce fabric sheet near my potted plants, if I happened to have a fabric sheet laying around.
But I would not, in a bajilion years, jump to the conclusion that it would protect me from all biting insects.
Long link to the paper, since the Researchblogging code keeps messing up blog code
Raymond A. Cloyd, et al. (2010). Bounce® Fabric Softener Dryer Sheets Repel Fungus Gnat, Bradysia sp. nr. coprophila (Diptera: Sciaridae), Adults. HortScience, 45, 1830-1833
I was interviewed by Drunken Skeptics (Michigan Skeptics Association) about DDT, bed bugs, and my criticism of Brian Dunning for not doing proper research and posting a lot of incorrect stuff about DDT.
I’m actually rather pleased with how it turned out, although you can clearly tell I had a cold. I’m interested in feedback from some of my fellow bloggy entomologists about whether you think I represented the larger entomological community’s views on DDT correctly.
The biggest complaint I have about the whole manufactured controversy surrounding DDT is that it’s a waste of time and energy, and distracts from the real work we need to be doing. DDT boosters like to frame the argument as: “Which is worse, Malaria or DDT?”
They have framed that question so that there is only one possible choice. A forced choice between Malaria and DDT is the WRONG QUESTION. I completely reject that false dichotomy as oversimplification. There are more than two choices.
The real discussion that needs to happen is about the best way to control malaria and improve human health in a particular situation. Over 99 countries have a malaria problem. It is patently absurd to think that one chemical can solve a problem that is global in scope. DDT is part of current WHO treatment guidelines. But it is only one piece of a huge, huge complicated problem.
What is the political, environmental, and socio-economic situation of a particular community struggling with malaria control? What, if any, data do we have on the resistance of the parasite and mosquito vectors to drugs and insecticides? It is not a one-size-fits-all problem with one solution.
Because of the vitriol that is spewed, people like me (and probably a few politicians) are hesitant to talk about Malaria at all. It makes aid to the WHO and Africa a political football that is used to score points. It’s not, really, about DDT at all. It’s about tarring and feathering the environmental movement, and keeping people distrustful of science.
And that is sad.
I’d really like to type up a transcript for the podcast, but I still am under the weather health wise–hopefully I can do that next week.
2010 is an important year. There’s 249 days left until the day set as the target for “The Decade to Roll Back Malaria.”
The plan is that by the end of 2010:
- 80% of people at risk from malaria are using locally appropriate vector control methods such as long-lasting insecticidal nets (LLins), indoor residual spraying (irS) and, in some settings, other environmental and biological measures;
- 80% of malaria patients are diagnosed and treated with effective anti-malarial
- in areas of high transmission, 100% of pregnant women receive intermittent preventive treatment (iPT);
- the global malaria burden is reduced by 50% of the 2000 levels: ~175-250M cases annually and less than 500,000 deaths annually from malaria.
This graph from the Global Malaria Plan shows the projected effects of these interventions on different timelines. Acting quickly will save lives.
What can we, as individuals in the US, do?
Nothing but Nets is one way to contribute. Let major pharmaceutical corporations know you applaud (and expect!) their efforts to lower pricing on malarial drugs. Lastly, let your legislators know you support funding for malaria research and aid.
That last one is hard–right now things are pretty tight in the US for a lot of people. I’m having some serious issues in my life right now.
But I’m still so, so privileged to live in a place with clean water and electricity on demand and little threat of infectious disease (relatively). Don’t forget that even now, as financial times are hard, we still are pretty darn lucky compared to our brothers and sisters in Africa, Asia, and South America struggling with malaria.
What will YOU do today?
Just when I think I’ve seen everything…I discover there is an app for your iPhone that claims to repel mosquitoes with high frequency sound:
“Have you ever been camping and you were worried about those mosquitos [sic] outside near your camp light? Wondering how soon it will be before they attack you in your sleep? Well, today’s the day that the “AntiMosquito” app will save your life! It produces ultrasonic-sounds, ranging from 16 KHz to 20 KHz, at frequencies that are way too high for us — humans — to hear!
I personally tried this app when I was on vacation and it worked perfectly! There is one downside to this app, but it’s not really the developer’s fault but rather Mother Nature’s: other animals can here [sic] these sounds and could make them go crazy. The only other problem is that a few people stated that some mosquitoes (again Mother Nature) aren’t affected by these sounds. So a “patch” would be appreciated to cover these specific mosquitoes.”
And, gentle readers, I believe you know what I’m going to say about this:
I have covered, in detail, the utter failure of any ultrasound device to repel anything besides common sense.
And, perhaps, money is also repelled out of your wallet.
The developers of this app have clearly gone to a great deal of time and trouble to make this thing look like it’s doing something. And, for all I know, if the iPhone is *capable* of producing sound in these frequencies–which is doubtful–it may really be doing so. However, that doesn’t change the fact that ultrasound has been shown again and again and again over the last 20 years to utterly FAIL at repelling mozzies.
I would like to direct your attention to this excellent publication by Purdue University’s Extension service.
I can provide that note in a PDF form, if you would like to print it out and have it handy to give to credulous folks that want to tell you that this app does anything.
DEET is the gold standard for insect repellent. I’ve covered it fairly extensively at the Bug Blog–it’s the best thing we have to prevent a wide spectrum of insects from biting and transmitting an even wider spectrum of diseases.
Some new DEET research was published this month, and the media…well, has done a crappy job of covering it. Here’s the latest headline: Insect Repellent DEET is Neurotoxic.
One thing all the news stories have in common is a very alarmist tone, and reprinting freely from a press release that has very little connection to the reality of the paper. When you look at the research, they did NOT find that DEET is neurotoxic, and it does NOT cause nerve damage.
Here’s the take home:
If you decide not to use DEET insect repellent on the basis of this bad journalism, you are probably putting yourself in danger. DEET is really the only repellent we have that can deal with ticks, and also protects against a wide range of biting flies.
The results in this paper are preliminary, need to be confirmed, and even IF confirmed, remain irrelevant to the average person who might want to use DEET.
Right, that’s the message.
Now to the details.
Here is what the researchers ACTUALLY found:
Corbel, V., Stankiewicz, M., Pennetier, C., Fournier, D., Stojan, J., Girard, E., Dimitrov, M., Molgo, J., Hougard, J., & Lapied, B. (2009). Evidence for inhibition of cholinesterases in insect and mammalian nervous systems by the insect repellent deet BMC Biology, 7 (1) DOI: 10.1186/1741-7007-7-47
“electrophysiological studies were performed on isolated mouse phrenic hemidiaphragm muscles. We showed that 500 µM deet prolonged by about threefold the decay time constant of synaptic potentials on endplate regions of the muscle fibre…”
Here’s a translation into English (by me):
We put DEET directly onto mouse cells and insect neurons in test tubes. It had a mild inhibitory effect on an important enzyme. The amount of DEET we used on mouse cells was 500 times the level that was active for insect cells. The amounts we used were several orders of magnitude larger than you would ever encounter in life as a human user of DEET repellent.
The best breakdown of this story I’ve seen yet was at Neuroskeptic. In fact, Neuroskeptic saved me a whole lot of time and work by writing an excellent article that I will now swipe here and quote freely:
“the fact that DEET can act as a cholinesterase inhibitor in the lab changes nothing. It’s still safe, at least until evidence comes along that it actually causes harm in people who use it. You can’t show that something is harmful by doing an experiment showing how it could be harmful in theory.”
This paper, when combined with decades of DEET usage data with very, very few adverse affects reported, is really not news at all. It’s interesting, sure. But it’s not at all relevant to the average American trying not to be bitten while BBQing.
I also agree with this statement from Neuroskeptic:
“To be fair, there is one cause for concern in the paper – in the experiments, DEET interacted with other cholinesterase inhibitors, leading to an amplified effect. That suggests that DEET could become toxic in combination with cholinesterase inhibitor insecticides, but again, the risk is theoretical.”
In some situations, DEET is combined with other compounds that it could, potentially, interact with–but that almost never happens in the US. Those situations are more common in military and tropical uses. This is a good note to be careful, and to monitor that in the future. There is also some (laboratory) evidence that sunscreen can increase absorption of DEET, and the two should be combined with caution.
If you are using DEET sensibly, you have nothing to worry about.
What is sensible DEET use? Borrowing from The American Pediatric Society, as well as my own experience: