A Potential New Treatment for Bats with White-Nose Syndrome

Almost a decade ago, wildlife biologists were flummoxed when they began finding bats with faces that looked as though they’d been dipped in white powder—the few remaining survivors of an unidentified plague that nearly wiped out their colony. The disease, later named White-nose Syndrome (WNS), is caused by the fungus Pseudogymnoascus destructans and was first found in the U.S. in 2006. Since then, the fungus has been found in 26 states and five Canadian provinces, spread by infected bats and unaware hikers, and is thought to have killed 5 million to 6 million bats

But now researchers have developed a bacterial weapon against the white nose fungus, and they've successfully tested, treated, and released a small group of bats in Hannibal, Mo. While we're still waiting to see how the bats fare, this is a promising treatment for the seven U.S. bat species (and 11 in Europe) known to be infected with WNS.

P. destructans attacks bats in two ways: It alters their arousal periods from winter hibernation, causing them to awaken more frequently and expend energy that needs to last them through the winter; and it directly damages the membranes of the bat’s wings, leaving them grounded. In its advanced stages, the fungal growth is visible on the wings and on the nose, looking like a harmless bit of dryer lint—but it can kill up to 99 percent of bats in affected caves. The average mortality rate is 90 percent. 

Why is this so alarming? Because bats are some of nature’s unsung heroes. Though feared by many (a phobia known as chiroptophobia), bats are almost universally harmless to humans. Human bites are exceedingly rare, and less than one percent of the notorious blood-sucking vampire bats are positive for the dreaded rabies virus. And while many species of bats can carry exotic viruses such as Ebola, the risk of cross-species transmission of these viruses to humans is very low.

In fact, bats improve public health in myriad ways. They pollinate plants; provide guano (bat poop), used as a beneficial fertilizer in some areas; and eat mosquitoes and other pests, protecting humans from mosquito-borne diseases (according a 2011 Popular Mechanics article about the disease, "The bats killed by WNS in 2009 left enough insects uneaten this year to fill 693 tractor-trailers," which is a lot of bugs) while saving the U.S. agricultural industry an estimated $3 billion a year. Even vampire bats aren’t all bad: A chemical from their saliva is being investigated as a "clot-buster" for stroke victims. 

To counter the fungus's ravages, Georgia State University's Chris Cornelison and colleagues have identified compounds produced by a species of bacteria called Rhodococcus rhodochronus that kills P. destructans in the laboratory. It's these bacterial compounds they used to treat 150 bats experimentally and release 25 of them back into the wild this past spring in Missouri, raising hope for a way to not only treat infection but potentially prevent it in the first place.

We won’t know about the bats' survival until later in the fall, but if this bacterial warfare works, it may save not only bats, but also amphibians infected with their own devastating fungal disease.

Deb Wright
The ‘Yoda Bat’ Gets an Even Cuter Name
Deb Wright
Deb Wright

The fruit bat formerly known as Yoda has found its forever name. Scientists christened the happy tube-nosed fruit bat in the Records of the Australian Museum.

The genus Nyctimene comprises 18 species, all of which live in Oceania and southeast Asia. They’ve got bright fur and faces, and noticeable spots on their wings. They will do just about anything for a mushy piece of fruit.

The family tree is no stranger to memorable common names, with cousins like N. draconilla, the dragon tube-nosed bat, and N. masalai, the demonic tube-nosed bat.

But wacky names aside, it would be hard to spot the dragon or the demon amid a lineup of other Nyctimene species.

“Bat species often look similar to each other,” biologist and co-author Nancy Irwin of York University said in a statement, “but differ significantly in behavior, feeding, and history.”

The newest member of the family showed its smiling little face during a field survey of Papua New Guinea in the late 1990s. Surveyors brought the bat to Irwin, who suspected it was a separate species. For its wrinkly ears and sage but goofy smile, she nicknamed the bat Yoda.

To confirm that they did, in fact, have a new species on their hands, Irwin and her colleagues combed through the scientific literature and museum collections. They examined nearly 3000 bat specimens from 18 museums.

A happy tube-nosed fruit bat with her baby and a postage stamp featuring an illustration of an unknown tube-nosed fruit bat.
Happy tube-nosed fruit bat (L) and a postage stamp (R) showing an unknown Nyctimene species, because they all look the same.
(L) Nancy Irwin; (R) Illustration by Julie Himes.

Many years and many, many research hours later, Irwin and her colleagues can confidently say the Yoda bat is a species unto itself. But they won’t call it Yoda anymore—since, as Irwin points out, most local Papuans have never seen the Star Wars movies, and the word "Yoda" means nothing to them.

She went with Hamamas (a local word for happy) instead. Its full name is the Hamamas tube-nosed fruit bat, Nyctimene wrightae sp. nov. (new species). The species name was chosen in honor of conservationist and scientist Deb Wright, who spent two decades exploring and protecting Papua New Guinea wildlife.

“Until a species is recognized and has a name,” Irwin says, “it becomes difficult to recognize the riches of biodiversity and devise management. Fruit bats are crucial to rainforest health, pollinating and dispersing many tree species, therefore it is essential we know what is there and how we can protect it, for our own benefit.”

SMBishop, Wikimedia Commons // CC BY-SA 3.0
Bats Yell, Too
SMBishop, Wikimedia Commons // CC BY-SA 3.0
SMBishop, Wikimedia Commons // CC BY-SA 3.0

Imagine you’re in a noisy restaurant, trying and failing to place an order. “IT’S VERY LOUD IN HERE!” you shout to your server, who shrugs. Now imagine that same conversation conducted super-fast, at a pitch so squeaky-high that you can’t even hear it. Researchers say bats are incredibly speedy at recognizing when they need to start shouting. A report on the bats’ raised voices is forthcoming in the Proceedings of the National Academy of Sciences.

Humans, bats, and other animals often start our conversations at one volume, then adjust as necessary. Study co-author Ninad Kothari of Johns Hopkins University says this seemingly simple action, called the Lombard effect, has proved complicated to understand.

“Scientists have been wondering for a century—could there be a common auditory process to explain how this phenomenon happens in fish to frogs to birds to humans, species with wildly different hearing systems?” Kothari said in a statement.

Previous studies had found that the Lombard effect takes about 150 milliseconds for birds and bats, and between 150 and 175 milliseconds for people.

Human listening, like human speech, can be messy, slow, and difficult to study. But bats’ echolocation squeaks and chirps are quick and precise, which makes them excellent scientific subjects.

Kothari and his colleagues Jinhong Luo and Cynthia Moss, also of Johns Hopkins, trained big brown bats (Eptesicus fuscus) to sit calmly on little platforms surrounded by recording equipment. The researchers set up an automated pulley system that brought insects zooming toward the bats, then listened as the bats hunted, bouncing sound off the approaching meal. Sometimes they let the bats go about their business in silence; other hunting sessions were interrupted by bursts of loud white noise.

The results suggest that earlier speed estimates had been way, way off. Just 30 milliseconds after hearing white noise, the bats got louder. That’s a “remarkably short” reaction time, the authors say.

“Typically, we breathe every three to five seconds, our heart beats once per second, and eye blinking takes one-third of a second,” Luo said in the statement. “If we believe that eye blinking is fast, the speed at which an echolocating bat responds to ambient noise is truly shocking: 10 times faster than we blink our eyes.”

Not bad, bats. Not bad.


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