Jan 112018
 


Mysterious cases of white-nose syndrome plague thousands of bats each year, frosting their snouts in toxic, white fungus. But researchers are fighting back against the dark reality—with light.

A new study, published January 2 in the journal Nature Communications, shows that ultraviolet rays, the light source behind black lights and sunburns, irreparably break down the fungus that causes white-nose syndrome in bats. The study results might provide clues for how to stop the deadly pathogen that’s currently on a trajectory to decimate bat species throughout North America.

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White-nose syndrome has wiped out an estimated 5.7 million bats since it was first discovered in a New York cave in 2006. The disease, caused by the fungus Pseudogymnoascus destructans, sprouts on the wings, muzzles, and ears of bats hibernating in the cold and dark caves of North America.

A little brown bat with white-nose syndrome hibernates in New Hampshire. Photograph by Stephen Alvarez, National Geographic Creative

The fungus disturbs the bats during their winter hibernation and messes with their bodies’ chemistry. Frequent awakenings caused by the fungus deplete the mammals’ energy and make them too exhausted to survive.

These Bats Mysteriously Survived a Killer Fungus

Although the fungus is fatal to many North American bats, their Eurasian counterparts have adapted to the growth after living with it for several million years. (Read: “Deadly Bat Fungus Spreading in U.S.”)

Government and academic researchers alike wanted to find out what causes the P. destructans to turn deadly. In the lab, they compared the fungus’s genes with six of its non-pathogenic relatives by exposing them to DNA-damaging ultraviolet light and studying how they reacted.

All the organisms held up against ultraviolet light, except P. destructans, which broke down under the rays. Only 15 percent of the fungus could withstand low doses of UV light, and moderate radiation destroyed all but 1 percent of it. A few seconds directly in front of a UV light source decimated most of the fungi.

“It’s not something that you would necessarily expect,” says lead author and USDA botanist Jon Palmer.

P. destructans grows in cold, dark caves where temperatures fall between 39 and 68 degrees Fahrenheit. But most organisms that thrive in darkness can still repair DNA damage caused by ultraviolet light, Palmer says.

“It was missing this key enzyme in DNA repair,” he says. “The fungus was very sensitive to UV light.”

Now that scientists know how to break down the fungal pathogen in the lab, the next step is taking the research out to the field.

Good in Small Batches

Marm Kilpatrick, a University of California biology professor who was not involved in the study, was excited to hear about the results when they were first announced at a conference in 2016. He’s curious about how the experiment might play out with real bats in caves rather than specimens in petri dishes.

But, he says, it would be difficult to treat tens of thousands of hibernating mammals at once. The fungus is visible on bats’ noses, but it also grows in the crevices of their closed-up wings. A noninvasive flash of light probably wouldn’t do much to stop the fungus from killing bats.

“It seems potentially exciting probably for smaller-scale treatments,” Kilpatrick says. “You’ll probably have to grab each individual bat and expose them to the UV light.”

Going into colonies and treating them with ultraviolet light multiple times over the course of one winter could disturb the bats’ hibernation, Kilpatrick says. Exhaustion caused by insufficient rest is one of the reasons why white-nose syndrome succeeds in killing the animals in the first place.

Kilpatrick and his colleagues have researched the effect of different amounts of P. destructans on hibernating bats. If a few UV treatments could kill off enough of the fungus before it turns deadly, that could be enough for some bat species to survive the winter.

A Bright Future for Bats?

Following this study, co-author Dan Lindner received a grant from the National Fish and Wildlife Foundation’s Bats for the Future Fund to continue research on how to fight the disease-causing fungus with ultraviolet light. The ongoing study will use light to treat bats naturally infected with P. destructans and see if it helps them survive hibernation.

“We’re very excited about moving this from the lab to actually working with bats,” Lindner says.

Pictures of Different Bat Species

A Mexican free-tailed bat comes in for a close-up as it leaves its cave to hunt. Every night from March to October, 1.5 million of these bats stream out from beneath a bridge in downtown Austin, Texas. Photograph by Joel Sartore with Cole Sartore, National Geographic Creative

Taken in 1915, this flashlight-lit photo shows hundreds of small bats in a grotto. Many species of bats call caves their home. (Watch: “America the Wild: The Bat Cave!”) Photograph by George Shiras, National Geographic Creative

Not all bats eat bugs, or blood. Some prefer flower pollen, which they pass from tree to tree. In fact, some plants are pollinated exclusively by bats. Photograph by Merlin Tuttle, National Geographic Creative

The little red flying fox is a type of bat native to Australia. Here one is tested for the Hendra virus, which is a rare but potentially lethal virus that can be passed from bats to horses, and then from horses to humans. Photograph by Lynn Johnson, National Geographic Creative

Did you know that some bats can fish? Here a greater bulldog bat uses its claws to pluck a minnow from the water. These bats use sonar to detect tiny ripples on the water’s surface. Some bats can catch up to 30 fish in a single night. Photograph by Christian Ziegler, National Geographic Creative

Not all bats prefer to roost in caves. The spectacled flying foxes pictured here are happiest high in the canopy of the rain forest. Photograph by Jason Edwards, National Geographic Creative

Some tropical species, like these Honduran white bats, have been observed to make tents out of leaves. The tiny bats bite through a leaf’s veins so that it droops down and forms a crevice for them to hide in. Photograph by Konrad Wothe, Minden Pictures

Noack’s roundleaf bats huddle by the thousands in a cave on Bioko Island, Equatorial Guinea. This species is one of the most common bat species in Africa. A single colony can contain perhaps 500,000 individuals. Photograph by Joel Sartore, National Geographic Creative

Three striped yellow-eared bats roost together under a leaf. These kinds of bats are rather uncommon, occupying mature forests from Nicaragua to Ecuador. They are thought to roost in harems consisting of one male and several females. Photograph by James Christensen, Minden Pictures

White-nose syndrome has ravaged the wings of this little brown bat. In just eight years, the disease has killed more than six million bats in the United States and Canada. (See “Bats May Be Wiped Out by Fungus in U.S. Northeast.”) Photograph by Stephen Alvarez, National Geographic Creative

A bat gets a fresh dusting of pollen while trying to eat the nectar of a blue mahoe tree in Cuba. In Mexico, bats are important pollinators of agave, which is used to make tequila. The next time you have a margarita, remember to thank a bat! Photograph by Merlin Tuttle, National Geographic Creative

Nearly 183,000 gray bats cluster together on a wall of Hubbard Cave in Tennessee. The cave houses more than 500,000 gray bats each winter, and the entire species is known to use just eight or nine caves across the American southeast. Photgraph by Stephen Alvarez, National Geographic Creative

A flying fox hugs its baby tight beneath folded wings in Nitmiluk (Katherine Gorge) National Park in Australia. Like all mammals, mother bats nurse their young with mammary glands that produce milk. Photograph by Jason Edwards, National Geographic Creative

A colony of Egyptian fruit bats hang out in a cave in the Maramagambo Forest of Uganda. Scientists tested the bats for the Marburg virus, since fruit bats are a natural reservoir for the disease. Photograph by Joel Sartore, National Geographic Creative

An orange nectar bat extends a long, nimble tongue to rob a bromeliad flower of nectar. Like a hummingbird, the bat hovers near the flower long enough to insert its tongue and lap up the flower’s sweet reward. Photograph by Merlin Tuttle, National Geographic Creative

While this photo might conjure up the image of a vampire, this is nothing more than a harmless fruit bat. Only three species of bats feed on blood. The rest dine mostly on insects, fruit, and nectar. (Watch: “Vampire Bats.”) Photograph by Joel Sartore, National Geographic Creative

This article was first published by National Geographic on 03 Jan 2018.

 

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Deanna Joy Sabourin

I love bats!

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