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:

BULL.

SHIT.

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.

Whatever Works For You: “New Magical Remedies for Pest Eradication”

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.

So…Sigh.
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…”

Wha? Ah.
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:

This week the Ecological Society of America is having their annual meeting, and several papers of entomological interest have been presented. One found that increased pollution in urban streams leads to increased mosquito populations:

“Luis Fernando Chaves, a post-doctoral researcher at Emory University, and his team discovered mosquitoes in abundance in a sewage-contaminated stream in Atlanta, but rarely in a nearby clean stream. They also found that mosquitoes were largest in streams with high levels of organic minerals – in this case, nitrogen and phosphorous – that originated from the sewage treatment plants.”

The issue of sewage runoff is a major one here in Michigan. 

Many of our cities use the same pipes for sewer water and storm runoff.  This means that in a heavy storm, excess water–with all that sewage too–goes right into the watershed.  This usually means the Great Lakes or other bodies of water.

Signs posted warning against swimming because of high fecal bacterial counts are a pretty common sight here.  Sadly, because of Michigan’s state budget woes, the annual required report of wastewater release has been suspended, effective April 2009.  Right now, there is simply not enough staff to monitor our water safety.

Chaves’ work suggests a double whammy–all those bacteria are wonderful food supplies for the bacteria that feed mosquitoes. And the mosquitoes are bigger, which means they can live longer–and have a better shot at transmitting a mosquito-borne disease, of which there are many.

You can read some research about storm runoff closer to home in the Journal of Great Lakes Research–here’s a couple of representative papers:

McLellan, S., Hollis, E., Depas, M., Van Dyke, M., Harris, J., & Scopel, C. (2007). Distribution and Fate of Escherichia coli in Lake Michigan Following Contamination with Urban Stormwater and Combined Sewer Overflows Journal of Great Lakes Research, 33 (3) DOI: 10.3394/0380-1330(2007)33[566:DAFOEC]2.0.CO;2

Tracie M. Jenkins, Troy M. Scott, Mechelle R. Morgan and Joan B. Rose (2005). Occurrence of Alternative Fecal Indicators and Enteric Viruses in Michigan Rivers Journal of Great Lakes Research, 31 (1), 22-31 : doi:10.1016/S0380-1330(05)70235-5

Link to Chaves’ home page

Great Lakes Assessment of Urban development and Water Quality

In case you missed it on my Twitter stream..a tribute to Michael Jackson. In Alaska. With Skeeters.

Field Biologists ROCK.  And I told you I was dressed accurately!!

Sociological Images caught something very interesting—packaging the same mosquito repellent product in two different ways:

“the mostly blue package includes a male figure fishing and logos for hunting, camping, and fishing. ….the mostly orange package includes a female figure, perhaps on a walk.”

In addition to the colors, there are completely different fonts and images on each package.

Seriously? Is it that important to have gendered packaging for even this??
At least they didn’t have pink and blue versions.  Sigh.

I also have to question if this product will work, given the dismal performance of repellent wrist bands.  There are larger photos here, but I couldn’t quite make out the active ingredients.  It’s apparently a fan that blows out… something.  Frustratingly, the OFF product page has no information about what is being blown around.

Eventually, I discovered the active ingredient is Metofluthrin, which has been shown to be repellent to mosquitoes. However, the trial I linked to…only compared to a control:

“89–91% reductions in landing rates compared with controls. Similar reductions in biting activity were also noted.  Following these tests, field trials to assess effect on landing rates were conducted with emanators positioned 1.22 m on either side of volunteers protected from biting by Tyvek® suits, with pre- and posttreatment counts being made. In Florida (predominantly Ochlerotatus spp.) 91–95% reductions were noted 10–30 min after emanators were deployed, while in Washington State (mostly Aedes vexans) 95–97% reductions were observed.“

Now, that’s not too bad, but note that this was a test with TWO of these thingies on either side of the test subjects—not wearing it at the belt, as is shown on the product.  I’d like to see it compared to traditional DEET repellent to really know how it holds up.

Frankly, I’ll stick to DEET, but there may be some folks less attractive to mosquitoes than me that this works well for.  (I am a mosquito magnet, so usually need extra repellent.)

LUCAS, J., SHONO, Y., IWASAKI, T., ISHIWATARI, T., SPERO, N., & BENZON, G. (2007). U.S. LABORATORY AND FIELD TRIALS OF METOFLUTHRIN (SUMIONE®) EMANATORS FOR REDUCING MOSQUITO BITING OUTDOORS
Journal of the American Mosquito Control Association, 23 (1), 47-54 DOI: 10.2987/8756-971X(2007)23[47:ULAFTO]2.0.CO;2

And now…back to World Malaria Day [Week] here at the Bug Blog.  This has to be one of the most charming rap songs ever–a group of Atlanta kids do a rap song for Nothing but Nets.

I am very curious about the curriculum in which these students were introduced to malaria and Nothing but Nets. I can imagine some things you might do, but it’s a pretty complex topic. Anyone know?

Welcome to the second day of World Malaria Day [week] at the Bug Blog! I’ve talked several times about the way in which different mosquitoes respond differently to pesticides for malarial control, but here’s a new twist.

In a recent study to compare different species of mosquito in their ability to be a malarial vector, there were very large differences!

As a review– a disease vector is an organism that does not cause disease itself, but transmits an infection by transporting pathogens from one host to another. The malarial parasite is alive inside the mosquito, although they don’t get malaria–but they can give it to us, the host. In this research, different mosquitoes were compared in their abilities to serve as a vector for malaria.

One of the claims frequently made by the “DDT will solve everything” crowd is that just spraying enough DDT will kill all the malarial mosquitoes.  This ignores that mosquitoes vary widely from population to population, and species to species, in their ability to resist DDT.  They aren’t all the same, and there is no one size-fits-all control method.

The research I discussed yesterday is another good example of the variability problem–predicting malaria using weather and other environmental data in different areas of Africa required different solutions.

In this experiment, you can get a sense of another layer of difficulty in controlling malaria. The experiments looked at two different strains of malarial parasite (Thai and Korean), and 3 different mosquito species.  That’s a lot of potential variation!

What did they find out?

I won’t go into the specifics–you can read the paper if you want to see technical words like “sporogony”–but basically, not all of the mosquito species were able to support the malarial parasites’ life cycle.  (BTW, this diagram is probably the single greatest cause of drinking in invertebrate zoology students. The names! The stages! Ugh!)

Infecting a mosquito with the malarial parasite isn’t enough–the parasite has to change, migrate out of the gut of the mosquito, and into its salivary glands.  Not all mosquito bodies are equally friendly to this process–there were large differences between the 3 mosquitoes tested in this experiment.

Hopefully this gives you a sense of the complex layers of difficulty surrounding malarial control–in addition to the environmental variability  from location to location discussed yesterday, and variation in pesticide resistance which I’ve discussed before, there are also large genetic differences within mosquito species, mosquito populations, and malarial parasites. It’s a spaghetti tangle of variables, many of which we have no control over.

This is why there is no easy solution to malaria, and why after centuries, we are only now beginning to make progress.

But we are making progress! Just not as fast as we’d like.

Citation:
Joshi, D., Choochote, W., Park, M., Kim, J., Kim, T., Suwonkerd, W., & Min, G. (2009). The susceptibility of Anopheles lesteri to infection with Korean strain of Plasmodium vivax Malaria Journal, 8 (1) DOI: 10.1186/1475-2875-8-42

So much new and interesting malaria research has been coming out lately, I thought I’d post some as we approach World Malaria Day.  Here’s an assortment of research that shows how knowledge of basic mosquito biology and ecology can help control malaria.

First, a neat study that combines entomology and hydrogeology in Niger:

“efforts to control environmental factors –such as working to eliminate the low spots where pools of water collect during the rainy season, or applying locally grown plant materials to limit the growth of mosquitoes — can have a dramatic effect on controlling malaria’s spread. And unlike importing expensive medicines, such an approach can rely on local efforts as simple as having people with shovels fill in the low spots in the terrain.”

Sometimes the simplest tools are the best!  Because mosquitoes need a week or so of standing water to reach maturity (the bitey stage), getting rid of the water, or helping it drain faster, is a locally-controlled way to stop the mozzies.  You can read more about this work (with lovely photos and diagrams!) on their laboratory pages.

Unfortunately, that may not work everywhere–in Gambia, the production of malaria-transmitting mosquitoes is too widespread (and unpredictable) during the rainy season for prevention. In fact, rice fields seem to be the main locations of mosquito breeding–so cultural control of mosquitoes would devastate the local economy.

Fillinger, U., Sombroek, H., Majambere, S., van Loon, E., Takken, W., & Lindsay, S. (2009). Identifying the most productive breeding sites for malaria mosquitoes in The Gambia Malaria Journal, 8 (1) DOI: 10.1186/1475-2875-8-62

Other authors used knowledge of mosquito life cycle, in combination with remote sensing data for vegetation and rainfall, to try to predict when malaria would be a problem in Sudan.  Modeling to predict outbreaks has been done for centuries, but now we have new tools that allow new variables to be added in.

Gaudart, J., Toure, O., Dessay, N., Dicko, A., Ranque, S., Forest, L., Demongeot, J., & Doumbo, O. (2009). Modelling malaria incidence with environmental dependency in a locality of Sudanese savannah area, Mali Malaria Journal, 8 (1) DOI: 10.1186/1475-2875-8-61

That’s a quick look at some environmental research on malaria–later this week I’ll look at some new research on bednets.

Just a little reminder that WMD is April 25th, 2009.

I’ll be covering some new and cool malaria research over the next week or two as we count up to  World Malaria Day. As a reminder, you can donate to Nothing But Nets online anytime.

Here’s a fascinating new bit of research that creatively gets mosquitoes to kill themselves:

Malaria prevention with a plastic flower:

“The small device is essentially an artificial flower, made out of the same type of plastic used for football helmets. Mosquitoes are drawn to the ProVector by a four-color decal (different mosquito species are attracted to different colors).

The insect feeds on an artificial nectar through a metal screen with openings big enough for only a mosquito’s mouth parts to fit through. Kollars’ work in developing the ProVector Bt formula is unique in that it is the first time anyone has been able to get mature mosquitoes to ingest and die from Bacillus thurengiensis (Bt), a safe biopesticide.”

I haven’t been able to find an actual citation for testing of this device– can anyone send that to me?  It seems like CO2 may also be involved in the attraction.  There are some news items about DOD testing, which might not be out in press yet.

Hmm. I am extremely skeptical about the success of this project.  From WSJ:

A quarter-century ago, American rocket scientists proposed the “Star Wars” defense system to knock Soviet missiles from the skies with laser beams. Some of the same scientists are now aiming their lasers at another airborne threat: the mosquito.

In a lab in this Seattle suburb, researchers in long white coats recently stood watching a small glass box of bugs. Every few seconds, a contraption 100 feet away shot a beam that hit the buzzing mosquitoes, one by one, with a spot of red light.

The insects survived this particular test, which used a non-lethal laser. But if these researchers have their way, the Cold War missile-defense strategy will be reborn as a WMD: Weapon of Mosquito Destruction…….

“We like to think back then we made some contribution to the ending of the Cold War” with the Star Wars program, Dr. Kare says. “Now we’re just trying to make a dent in a war that’s actually gone on a lot longer and claimed a lot more lives.”

The scientists envision their technology might one day be used to draw a laser barrier around a house or village that could kill or blind the bugs. Or, laser-equipped drone aircraft could track bugs by radar, sweeping the sky with death-dealing photons.

This story has been picked up and run all over.  The scientists named in it do seem to be legit, and Intellectual Ventures, LLC is a real company. But…

This really seems problematic. Especially since all that was shown was a video of a mosquito bursting into flame.  Was it real? Who knows.

None of the scientists named in this story seem to be entomologists, although it does say “Dr. Wood, Dr. Kare and another Star Wars scientist teamed with an entomologist with a Ph.D in mosquito behavior and other experts.” Anyone know who that ento is?

The scientists interviewed say they plan to put lasers in villages in Africa to protect them from malarial mosquitoes. (Presumably they will also invent a sustainable power supply to run it.)  Some stories also mention hand-held personal versions.  The current (non-killing) version in the demo requires a desktop computer to run it.

Would this be completely freakin’ awesome if it’s real?
Yes.
Good luck to them, and I hope it works.

However, I think this will be about as successful as the first Star Wars system. And I think the primary purchase of this news story is to drum up capital for Intellectual Ventures.