A short dose of ultraviolet light might save North America’s bats

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Researchers have found that the fungus that has been decimating bat populations in the eastern United States for the past decade is easily killed by a short dose of ultraviolet light.

Upon being compared to six non-pathogenic Pseudogymnoascus species, it was found that P. destructans lacks a key enzyme that allows it to repair DNA damage caused by ultraviolet light. When samples of the fungus were exposed to a low dose of UV-C light from a handheld source, the survival rate was only about 15 percent – this dropped to less than 1 percent when the dose was moderate. In both cases, the duration of exposure was a matter of no more than a few seconds.

Next comes a control group experiment. If this proves true, than it might be possible to safely sterilize both bat populations and caves of the fungus. To work, however, the task will likely require repeated yearly visits to bat hibernation sites to kill the fungus before it causes the bats to wake up in the winter. Such visits have their own problems, and would be difficult to pay for. However, I am sure the caving community across the U.S. would be glad to volunteer for this effort, and could handle it.



  • wayne

    Interesting development!

    I have a UV-C air sterilization-unit, hooked into my furnace, along with a Heppa filter. (UV-C is widely used in Hospitals and sterile pharmaceutical-manufacture, the bulbs are mass-produced and give off a nice warm blue light.)

    This reminds me a bit of Star Trek (Original) “Operation Annihilate,” when they had to kill the parasite-creatures with ‘light,’ and made Spock go blind (temporarily).

  • Orion314

    Thank the gods for the Vulcan inner eyelid!

  • wayne

    Prefer the bottom-up approach, but assuming this method works, I’d get the cave-people, selected animal advocates, and a UV-C bulb manufacturer together (to donate equipment,) and start forming plans to just zap caves, every time someone goes caving, on a strictly grass-roots basis, — no new “Department of Bat Habitat Irradiation,” coordinate between the people who know, and the people who care, and we’ll tell the Government, later.
    -How many miles of cave bat-habitat are we talking about?
    -How many people are into Caving?

    good stuff.
    [I’m totally convinced–‘shared cultural experiences,’ are the Kevlar, of our societal fabric!]

    I should say– you’re not supposed to stare at UV-C light, it breaks the chemical bonds of DNA, at the molecular level.
    (Our atmosphere screens out UV-C, otherwise we’d look more like Mars.)


  • Wayne: Your concept of using the cave community is exactly what I expect to happen. There are probably about 20,000 active cavers in the United States, scattered in small clubs throughout the country. Already I have seen communications suggesting something along these lines. The important areas, however, would be in the northeast, where the fungus exists, and which also happens to be the area with the most cavers, probably numbering around 5,000 to 10,000.

    The amount of cave habitat is smaller than the caves themselves, but you’d have to zap a lot of the cave itself to prevent the fungus from re-establishing itself on the bats, season by season.

  • Mitch S

    So the means exist to stop the fungus killing bats but why go through the expense/effort?
    Unless the fungus was man-made isn’t this part of a natural cycle?
    Will the loss of the bat population impact humans? (I suspect they have a role in insect control but is it significant?)
    Will letting nature take it’s course result in the bats surviving by developing a resistance to the fungus?
    Just asking…

  • wayne


    What! ….Bat-Lives, don’t matter! Only cute Mammal’s…. with fur and big eye’s? Huh?
    Just exactly what sorta Homo-Sapien centric Species-ist, are you! You just can’t hug a baby Bat, with Nuclear Arm’s, it’s just not happening. (It’s takes a Village to raise a Bat, for gods sake!) Get with the Program!

    –Just Kidding!

    >A most excellent point. Just because we think we can fiddle, doesn’t imply we should….

  • Localfluff

    I don’t want to sound like an environmentalist, the left have given these kinds of concerns a very bad connotation. But we maybe should think twice before gardening our paradise with UV-light, just because it happens to solve one specific problem, or imaginary “problem”. It might affect other things too.

    Saving species isn’t necessarily good. Like those cute Panda bears. Fat big animals who try to survive on eating bamboo shoots. That won’t work. They are well on the way to become exterminated because of this weird evolutionary mistake. Unless some aliens or apes drop by with super abilities to try to keep them alive in some zoo for our ape children to watch and find cute because of their random fur coloring pattern.

    Maybe Pandas are subconsciously preserved because that’s the kind of bear we could hug. Polar and Grizzly and even the standard blueberry eating brown bears, not so much. Bears are a one hug a lifetime kind of animals. But that is just a temporary sentiment. Panda bears were not a great show in the Colosseum. The Romans would’ve cooked them and served them to the audience. The Pandas don’t protest being exterminated.

    Maybe those bats “should” go away. Maybe that is a good thing. Maybe keeping them around will give this virus or whatever is happening in the unknown microbial world that we literally consist of, a base for exterminating many other species. Maybe the bats’ extermination is a good thing. We don’t like to think about animals that way, because animals are property for us. Seeing one’s animals die means bad times ahead, a lower stock market. But that’s just our gardening instinct, it does not represent all of how nature works. There’s a microbial war going on that we don’t master at all. Death and extinction is a part of it. We won’t do away with that.

  • wayne

    “The Legend of the Teddy Bear”

  • wayne

    Interesting take.

    You might like this-

    “Why Dragon’s?”
    The ‘Cat-Snake-Bird Monster,’ and innate biological fears.
    -Jordan B Peterson

  • Localfluff

    The fire breathing ‘Cat-Snake-Bird Monster’ might be an idea about combining abilities that are good for survival in a world of other predators. And most of all in a world where other apes have the same dangerous ideas as oneself! Putting together the best pieces of all known powerful animals (nothing from the panda there, unless one wants to mix in some cuteness). Viking graves have evidence of piecing together body parts, like a horse’s legs on a dog’s body. Heads and even carved off faces exchanged between skulls burried together and other obscene things that wouldn’t even make a horror movie so bad they seem to us today, but were funeral rituals then. In the days of the idea of the dragons being out there somewhere as our waiting doom (or funny pets).

    Looking up our collective knowledge on the matter, Wikipedia, I learn that “Here be dragons” being printed on maps really never happened. Except once in 1505 when it apparently referred to some really existing and dragon looking human sized lizards in the south eastern corner of the world. It is only in recent years that some freaks come out with their “Here be dragons!”-warning for going to Mars.

  • BSJ

    This is a bad idea. Darwinian evolution is working just fine with reestablishing bat populations.

    Introducing Darwinian evolution to the development a more hardy fungus will be completely counterproductive!

    It will be impossible to expose every spore, in a natural environment as complex as a cave, to a completely lethal dose of UV radiation. Therefore, some of the fungi will survive to reproduce and will be more resistant to UV exposure than their predecessors. So on and so on…

    Who’s to say that the surviving fungus won’t be even more injurious to the bats?

  • ken anthony

    Something terrifying has occurred in the last few years: CRISPR technology which now gives humans the capability to wipe out any sexually reproducing species by modifying a single member. A bright high school student assuming they have access to the lab equipment could do this.

    Unintended major consequences could result from extremely minor manipulations.

    Usually I don’t worry much about us wiping out our species and even this technology would take ten generations in humans to do the job. However, the food chain could be destroyed in less than a year. Currently the solution they depend on is not allowing a single creature out of the lab, but I have no confidence in this. It’s already failed many times in other cases. Even a plague getting out of a lab would have less consequence.

  • wayne

    speaking of crispr;

    “Could gene editing save chocolate from extinction?”

  • Edward

    Maybe if we had a Teddy Bat then bat-lives would matter. And we could hug it with conventional arms as well as nuclear arms.

  • wayne

    Good deal!
    (You mean, like with a cloth or something?!)

    “The National Wildlife Naming Fund”
    [Tom the Dancing Bug; Ruben Bolling]

    (Naming animals, is the key to protecting them! We are working hard, to Name every animal on Earth.)

  • wodun

    To work, however, the task will likely require repeated yearly visits to bat hibernation sites to kill the fungus before it causes the bats to wake up in the winter. Such visits have their own problems, and would be difficult to pay for.

    Wouldn’t it be possible to pre-place the lighting equipment and have it operate remotely? Do the lights wake up bats or would they sleep through it?

  • wodun: Your question strongly suggests to me that you have never gone caving. The variables are too great to place such devices practically. Moreover, you couldn’t operate them remotely with any ease. Communicating electronically into a cave is complicated and generally needs a wire.

    As for whether UV light would disturb the bats, we don’t really know. This is why a control experiment must be done, not only to see if the ultraviolet light kills the fungus, but whether it hurts the bats.

    I should note that I myself tend to agree with most of the commenters here who have expressed reservations about doing anything. From white nose syndrome’s first appearance I argued, vainly, that this was actually an opportunity to study an natural extinction, something scientists have not been able to do many times previously. The focus on saving the bats makes many miss this point.

  • Phill O

    Ultra-violet light is not good for humans: cataracts may develop prematurely with overexposure. Now, bats do not have great eyes I am told soooo.

    My concern is whether or not the fungi spores get airborne. If so, the deepest reaches could hold a reservoir.

  • wodun

    Robert Zimmerman
    January 3, 2018 at 8:29 pm

    wodun: Your question strongly suggests to me that you have never gone caving. The variables are too great to place such devices practically. Moreover, you couldn’t operate them remotely with any ease.

    Batteries + timer or even a motion detector.

    The whole thing sounds impractical, so I would expect that everything about any eventual plan to be so. It is doubtful that an entire cave system could be covered, the lights would have to be placed strategically knowing that OCD levels of coverage of every nook and cranny wont be achieved. Suitable entry and exit points would be a great way to get full coverage of a bat’s body, assuming the lights don’t prevent the bats from using them.

    For pre/post hibernation, you could even set up some conventional lights to attract bugs and then place UV lights to cleanse any bats that come to feed.

    I just come up with ideas, if you don’t like them I always have others =p

  • wayne

    “The following are incident energies of germicidal ultraviolet radiation at 253.7 nanometers wavelength necessary to inhibit colony formation in microorganisms (90%) and for 2-log reduction (99%).”

    “UV Irradiation Dosage Table”

  • Localfluff

    UV-sensitive fungus don’t exist on Mars’ surface. Take that you biohazard-ehum-hypocondriacs out there!

    Maybe the planetary safety idea comes from the biology direction rather than from the cosmology direction. While physics is too weird on quantum level or somewhere far far away, biology is frightening because it is her inside of us right now. And it is completely out of control for human comprehension, ever. Biologists are very afraid, for good reasons. Everything that happens within even any cube millimeter of your body will never be understood. It is mathematically proven to be beyond any possible calculation. One cannot fully calculate reality, reality is what happens. Calculations can only be a part of what happens. The computer is not a machine outside of this world, as we intuitively wish to think. We are much more super fantastic creatures than any religious idea has been able to imagine.

    Shining invisible light on some bats can’t be too bad. Lets use the very little knowledge we can have in order to take care of our paradise garden and the creatures it has given us to be our friends. All the animals and all the plants let themselves be tamed by humans, because we have a foresight they don’t. They all kind of realize that and give us a great allowance. Because we humans are what could make their heritage immortal and universial, by space flight.

    Hieronymous Bosch described human emergence into the life on Earth and beyond, already 500 years ago with his paintings (before Copernicus). I don’t recall seeing any cave bats in his motives, but those creatures would certainly have made his point. He even designed the Orion capsule!:

  • ken anthony


    Either we get our eggs out of the basket or we guard that basket by people that can’t.

    Seems we really have only one choice and not a lot of time to make it.

  • ken anthony


    So if I stayed in Olympia WA I could have been a chocolate farmer?

    I used to enjoy watching the bats flying at the treetops at night, but now can’t remember if that was in CA, WA or both? I wouldn’t be able to see them with my old eyes now.

  • Localfluff

    I’ve seen huge streams of bats, vampires actually, flying in over a city in Africa from some cave on a volcanic island just off shore. It is really like in the movies and cartoons. The coordination is what makes it kind of Hitchcock scary. A huge stream of bats crossing the sky at dusk in an invisible curved highway they have somehow made up in the air. Searching for blood! I’ve heard that each of them has to drink blood every night in order to survive, flying requires calories, but that they share blood between each other at home in the cave to save the lives of unlucky fellows.

    Or hear them, the bats, their navigational echo system. My parents always fished crayfish in the late summer. Bats flying and beeping all the time. They made the only sound there was while one was lying down watching the star sky and its occasional meteors and satellites, waiting for the crayfish to wake up from under their lake rocks and creep into the rotten baits in the cages to be caught and boiled alive. Horrible! And wonderful. Sonic bats, water spiders, satellites all in the darkness of night. Sounds pretty exotic when thinking of it now, but I just took it for granted back then. That was my back yard. And I of course fell into the water from slippery rocks or from the little rowing boat every night, worrying my mom.

  • BSJ

    To add, I’ve been seeing an increasing number of Little Brown bats each summer. For a while it was maybe one or two each evening. But the numbers are steadily rising over the years…

    I counted a couple hundred coming out of a my shed’s roof one night before I got bored and went inside. They were still coming out steadily.

    They were stinking up the shed so I was limiting their entry points until just one was left. I came back out later and they seemed to have all exited and I closed to the last hole. A few bats was OK. Hundreds, not so much!

    This is right before WNS hit….

  • BSJ: I don’t know where you live, but I am 90% sure you are not seeing Little Brown bats. About 3/4 of all bat species do not use caves, and the Little Browns, which do, were worst hit by white nose. Essentially, the population of Little Browns dropped by about 98%.

  • wayne

    I distinctly recall seeing some sort of Bat’s, when I was a child. (Lake Michigan coast area) They came out in the late evening. I wonder what I was really seeing?


    “What are you…?”

  • wayne: It is not unusual in the early evening to see bats flying about. They are harder to see later when the sky is dark, but in the early evening they silhouette against the sky. And they definitely fly differently than birds.

  • wayne

    Mr. Z.,
    OK, cool– they were definitely not birds. And yes– it was a distinct silhouette against the sky that was most noticeable. (it’s was ‘bat-like,’ and after dusk, but before full darkness.)

    Tree top level, and I think they made some sort of intermittent ‘squeaky’ type sound, but that could be a false-memory implant, co-mingled with watching Scooby Doo.
    (Have not seen a Bat in a long time, we do have Owl’s in the area, but they are hard to spot. We are up to our eyebrows in Deer & Turkey, and the Eagle population has been climbing substantially.)

    We sometimes tried to throw stuff up in the air to see if they would swoop down. And of course, the obligatory adolescent discussion on “Vampire Bats,” would ensue.

    We have a lot of watershed catchment area’s in my area, (leading into Lake Michigan)– I always assumed the Bat’s targeted insects in the wetter areas, and/or our extensive tree-crops. (something about “fruit Bats,” comes to mind.)

    Interesting little Creatures!!

    I was always sorta neutral toward them, despite our generally negative cultural portrayal of “bats.” but…I’ve been watching tooo much Jordan Peterson lately– and they are sorta ‘creepy,’ at a primal-level, but… just trying to make a living.

  • BSJ

    VT, across the lake from NY… I see ’em.

  • BSJ: If you saw those bats in the past decade, then I am certain they were not little browns. That species, once the most populous of the cave hibernating bats, was practically wiped out in the northeast by white nose. There has been a tiny recovery, but we are talking about numbers less than hundreds, not the tens of thousands that used to exist.

  • BSJ

    And, I’m talking about small numbers. Last summer it was like 7 or 8 at one time. Where it was 1 or 2. Or less in the beginning…

  • BSJ: I am very aware of this story. In fact I posted something here about it about a year ago. However, the numbers are still tiny. There are plenty of bats around, just not these.

  • Max

    Interesting topic and solutions. It’s too bad the bats don’t come out during the daytime to get natural UV light.
    What ever evolutionary pressures that caused the flitter mouse be nocturnal and to develop sonar to capture prey that has no heat signature, rather than night vision like other mammals (cats) or birds (owls) or Night hunting reptiles (snakes with heat sensitive skin) should not impede it’s ability to hunt the same insect food during the daytime.
    I’m thinking the reasons is biological. Perhaps UV sunlight which penetrates through thin skin does damage. Maybe species “must” hide itself from UV light. (except the larger tropical bats witch hang from trees)
    UV light, which can help a human child born with yellow skin, may cause chemical reactions harmful to the bat. The light, for example, may neutralize the chemicals required to break down the hardshell of the insects they eat, or the ability to detoxify the insecticides and pesticides that the insects are covered in.
    It’s ironic that the very thing they avoid the sun for has created the perfect breeding environment for the white nose fungus.
    Once a cave is contaminated, it could never be 100% cleansed. UV light may help, but it does not solve the problem that the bats immune system should already be taking care of. The fungus would eventually become UV resistant anyway. The fungus must have a natural enemy that will not kill the bat.

    “Here be dragons”
    I was talking with my nephews home from college for Christmas break. We were enjoying the warm weather of short sleeve southern Utah.
    The topic of carbon dioxide causing global warming came up (which made me smile) as I asked them to do the math…
    CO2 is 400 ppm which means that for every one CO2 molecule there are 2500 air molecules that it must warm up. To increase the temperature of the Air molecules by just 1°, that one CO2 molecule must radiate 2500°!!!
    That’s hotter than molten metal.
    Because air is constantly cooling, carbon dioxide must be heating continuously.
    Can you imagine trees absorbing CO2 bursting into flames? or fire coming out of your mouth every time you exhale?
    They said, like dragons? Like invisible dragons… probably made out of dark matter… absorbing dark energy… which manifests itself by heating our planet with their breath?

    Yeah, just like that. They not only found what’s causing global warming but proved the dark matter is real, and it’s dragons !
    This will disappoint the unicorn crowd. Perhaps the unicorns stay near clouds to avoid the dragons.

  • wayne

    interesting stuff!
    (I do enjoy you commentary.)

    Just a slight clarification; we do get UV-A and UV-B on our surface, but the atmosphere screens out UV-C, otherwise we would be a lot more like Mars.
    The table I linked to above ( “UV Irradiation Dosage Table”) should have specified it’s for UV-C exposure. (and at a specific wavelength.)
    (my air-cleaner manual does tell me that UV-C exposure is cumulative, and breaks molecular bonds at the DNA level.)

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