I'm very skeptical of these results: The sample size is much too small!
They started with only 64 individuals. Of those only ONE was found to be especially attractive to mosquitoes, and only TWO especially unattractive. They then used the scents from these three individuals, and 5 others who did not participate in the initial testing, for the following phases of research.
Also, of the 5 additional people, two were found to be especially attractive, and one unattractive. This is extremely inconsistent with the results from the first phase.
Now, they did a ton of work and show very interesting results. But these problems make all of their results very questionable in my mind.
Yes, followup research could shine more light on this to validate their results (or not), but I wish they would make less grand declarations about the meaningfulness of their results. I bet this is going to make the news around the world... and if it later turns out to be inaccurate, it's only going to further reduce the public's trust in science.
I don't understand what exactly you are complaining about. Can you elaborate on which specific statistical claim you think they should not make?
This is not an analysis of "what fraction of people are attractive to mosquitoes", it is about how mosquito attraction differs between people. You can make meaningful statistical claims about this with just two subjects (and lots of measurements, which they did - see e.g. Fig 1G).
I also don't understand how you complain about the insufficient sample size and then go on to claim the difference between two cohorts is "extremely inconsistent".
> You can make meaningful statistical claims about this with just two subjects
With just two subjects, there is a very high chance that the results of your testing are overly specific to those two subjects, and do not hold for most of the population.
With only 8 subjects, as in this study, that is still very true.
For example, people like the one person the mosquitos were extremely attracted to could be one in 10, one in 100 or one in a million. In the latter case, the findings are much, much less meaningful.
That's true even for the findings about specific genes affecting attraction. What if that one person is an extreme outlier and the mechanism causing the results isn't relevant for 99.9999% of the human population?
> Can you elaborate on which specific statistical claim you think they should not make?
For example, the claim that "Highly attractive people have higher levels of carboxylic acids on their skin" does not seem to be well enough backed by evidence in this case. If they wrote, "the one/three attractive people we tested had higher levels of carboxylic acids on their skin", I'd have no complaints.
> For example, the claim that "Highly attractive people have higher levels of carboxylic acids on their skin" does not seem to be well enough backed by evidence in this case.
I might be missing something, but do you not see additional evidence for this claim in the discussion around figure S4?
In my reading, the authors do go out of their way to point out that carboxylic acid presence is only one of possibly many more factors. (See also "Limitations of the study"). Most of that nuance is lost in the "highlights" section though, I would agree.
(I'm not GP) My answer would be that it's the difference between "Why do mosquitos have differential attractions to humans" vs "Why do mosquitos like Subject 33 more than Subject 28." The untestable assumption is that what makes Subject 33 more attractive to mosquitos than Subject 28 is generally applicable to the population at large. I agree intuitively with GP that finding 1/64 to be highly attractive in one sample and 2/5 in another would be surprising if this were following some binomial distribution, but the methodology for determining attractiveness was different between those participants (live test vs exposing mosquitos to a nylon that had been worn by the participant).
If the professor from my statistics class is anything to go by, you just need a sample of more than 32 and you can assume it's a normal distribution /s
> Chemical analysis revealed that highly attractive people produce significantly more carboxylic acids in their skin emanations. Mutant mosquitoes lacking the chemosensory co-receptors Ir8a, Ir25a, or Ir76b were severely impaired in attraction to human scent, but retained the ability to differentiate highly and weakly attractive people. The link between elevated carboxylic acids in “mosquito-magnet” human skin odor and phenotypes of genetic mutations in carboxylic acid receptors suggests that such compounds contribute to differential mosquito attraction.
I wonder if diet has any impact on this. Anecdotally one of my childhood friends in boy scouts was a vegetarian and my goodness was he a mosquito magnet. I’ve always wondered if there was some relationship with what protein you eat and how attractive you are to these insects.
Edit: keep the anecdotes coming. I mean no judgement on any diet. I really just want to understand what makes these horrible insects bite people because, while I was born in Iowa, I spent most of my young adult life in Minnesota and wew that state has a lot of mosquitoes.
I am a massive mosquito magnet, and I was initially a proper t-rex eating meat every day for 25 years but in the last ten years I’ve been 99% Pescatarian (mostly just veggie but sometimes fish or seafood) and I’m still the same massive mosquito magnet.
My wife was her whole life Vegetarian and she is the opposite of me, not a mosquito magnet.
Also personal anecdote; my wife and myself are longtime vegetarians and we never get stung. We generally don’t notice that there is anything bitey around us until magnets asking us if we can go inside because they are getting eaten alive (we have been in Florida for instance where a friend got 10+ bites in a very short time while we were sitting there outside long before him and noticed nothing until he ran inside; this friend is a real magnet as anti moz spray doesn’t help at all for him). It’s not only mosquitos though; things like flees, gnats, midges etc are also not interested in us; we always have to hear from others if there is something that bites.
But no idea if it’s diet related as I cannot remember how it was before I switched diet; too long ago.
I wonder if this is also applicable to bees. When I was a kid, we got caught up in a swarm (there were five of us hiking in the woods). I was walking through the swarm as though I wasn’t even there. I think I had maybe a handful on me the entire hour, while my friends were literally covered in them, even under their clothes and underwear. I never get bitten by insects, ever. I can count on one hand how many mosquitoes have bitten me in the last decade.
This has held true for me as well. I consider myself a delicious steak to my female companions disinteresting salad as far as mosquito's are concerned.
This has also given me an understanding as to why if you ever see any product reviews for DEET based mosquito repellent you'll inevitably see one or more people advocating some hippie tincture that's apparently better but has no terrible chemicals in it.
I always think there was probably a human mosquito meat shield nearby who was taking the hits for them.
>My wife was her whole life Vegetarian and she is the opposite of me, not a mosquito magnet.
A friend of mine was in the same situation - he was a magnet, his wife not. His explanation was - "She is so toxic, that they die if they bite her". Brave guy.
My wife and I eat nearly identical diets. When we are outside together she can be bit over a dozen times and I won’t be bit once. Furthermore, she has been highly attractive to mosquitoes her entire life spanning radically different diets.
Not sure why you got downvoted for asking a good faith question, but you’re thinking of carbonic acid, which is responsible for the fizz when the pressure lowers as you pop the top and it creates carbon dioxide.
I think carbolic acid found in soft drinks and carboxylic acids (there are many of them) are found in all sorts of things (coconuts, goat fat, fragrances, pheromones, etc) but not carbonated drinks, according to Wikipedia.
I wonder whether puberty has an effect? I was bitten to death as a kid, as an adult it's far, far less frequent (to the point where a single bite is 'a thing').
But that might also be because kid me played outside in the park in the evening/went camping etc., and if adult me is out in the evening it's usually sitting outside a bar.
Another article I read said they did multiple samples from people and the attractive people were always attractive. They said it rules out soaps and recently eaten food, but I guess "extreme" diets of vegan or carnivore wouldn't change much over a few months.
Someone in Southern California needs to figure out how to get rid of the recent explosion in Asian tiger mosquitos that have invaded the region.
It’s crazy how fast it’s happened.
Once the mosquitos start spreading one of the many terrible diseases they can carry the government officials will finally act, after it’s too late to save the first victims of an avoidable problem.
Horrible quality of life issue that should be fixable if the government officials can get their act together soon!
You can protect a small area (like a patio) reasonably well by stretching a mesh bag over the front of a box fan (the mosquitos get blown into the bag and can't escape).
Hm really? They get sucked into the fan? I'd imagine that a bag a fair distance from the fan would be better, as there more volume for them to get caught in the draft.
I read your comment and immediately thought 'uh-oh'. If there is some new mosquito in California, they'll be in the southeast in no time. Too late it appears. It's already old news. I guess no one noticed around here as we have so many insects anyways. No point in complaining to the authorities.
In cases where you can't actually see the mosquito, sure, but in cases where I've caught a glimpse of it and the swatter was nearby, I've had great success with them.
I’ve always wondered this, so will ask here since it’s relevant:
How certain are we that it’s a difference in whether or not someone is bit by mosquitos vs. whether or not (or how) someone’s body reacts to a mosquito bite?
I am a mosquito magnet, but my skin also deals with other oddness on occasion, plus I’m moderately allergic to a number of things. So part of me feels that may have some (more?) to do with it vs. that I’m bitten more.
E.g. I’ll often find myself riddled with mosquito bites without even having realized I was being bitten. So I imagine it’s possible for non-magnets to also be bitten but just not have the same reaction.
Anecdotally and IMO, I am definitely a mosquito magnet! Always have been and I'm sure I always will be.
Not so anecdotally: I get massive reactions from bites that last a long time (sometimes months).
For example: In my 20's I once went canoeing on the Russian river and drank all day. Since it was a hot day, I was pretty burnt out when my GF and I got back to our camp site late in the afternoon. Our site was probably about 200 yds from the river's edge and when we got back I pulled a sleeping bag out of the tent and laid down on it on the grass. I pretty much immediately fell asleep (drinking, heat) on top of the sleeping bag. I woke up a couple hours later after the sun had just set. I was covered in bites. For the next week or so I tried to count the bites and ended up settling on 107 mosquito bites! It took over 3 months for them to go away! Needless to say, I will never forget that experience and no one will convince me otherwise that I am not a mosquito magnet.
This specific study used samples of fabric rubbed in the skin oils of various people and then indexed which fabrics attracted the most mosquitos, most reliably, so while it may not be a guarantee that all mosquitos feed at the site they're most attracted to, I wouldn't think it's quite that big a leap... I imagine that they feed at the first known-good-human, generally speaking.
They also specifically call out that there are "low attractor" humans who simply don't generate as much of the carboxylic acid compounds that the mosquitos were attracted to, and who may still be bitten, but were not he preference.
People definitely react different to bites, though. I know plenty of people who don't really feel much of an itch, vs others for whom it's awful.
I have had maybe 3 mosquito bites in my life, despite having lived large stretches in the tropics.
Mostly they don't even land on me, but I have watched when they do - the closest they get to biting is lowering their proboscis until it touches skin. Then they fly off.
I always assumed it had to do with skin odour, probably diet related. It's surprising that the science isn't more advanced on this considering how harmful/annoying mosquitos can be and how primitive the current countermeasures are.
In the paper, they’re counting mosquitoes that fly into a chamber containing odor collected from skin. They calibrated that against people sticking their arms in a mosquito box and counting bites as they happened. So bite response shouldn’t affect the result.
Since my wife often has low levels of iron and never gets biten by mosquitos and for me the opposite my theory is that mosquitos also like iron rich blood. But I have never seen a study about this connection: https://www.verywellhealth.com/reason-mosquitoes-bite-some-p...
Really interesting, again super small sample size. It's just his girlfriend and him testing out who's more attractive using a lab experiment. I don't believe they were able to conclusively answer the question, even with the mosquitoes biting one person more than the other.
I had been thinking for a while, mosquitoes prefer certain smells, and use their olfactory senses to find targets.
Anecdotally, like others on the thread, I get bitten all the time in areas with mosquitoes, where my parents, others never did.
My friend, along with his father, are completely ignored by mosquitoes. I've seen him walk through clouds of them as they seek out anyone else and just ignore him.
They started with only 64 individuals. Of those only ONE was found to be especially attractive to mosquitoes, and only TWO especially unattractive. They then used the scents from these three individuals, and 5 others who did not participate in the initial testing, for the following phases of research.
Also, of the 5 additional people, two were found to be especially attractive, and one unattractive. This is extremely inconsistent with the results from the first phase.
Now, they did a ton of work and show very interesting results. But these problems make all of their results very questionable in my mind.
Yes, followup research could shine more light on this to validate their results (or not), but I wish they would make less grand declarations about the meaningfulness of their results. I bet this is going to make the news around the world... and if it later turns out to be inaccurate, it's only going to further reduce the public's trust in science.