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.

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How Bats Protect Rare Books at This Portuguese Library
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Visit the Joanina Library at the University of Coimbra in Portugal at night and you might think the building has a bat problem. It's true that common pipistrelle bats live there, occupying the space behind the bookshelves by day and swooping beneath the arched ceilings and in and out of windows once the sun goes down, but they're not a problem. As Smithsonian reports, the bats play a vital role in preserving the institution's manuscripts, so librarians are in no hurry to get rid of them.

The bats that live in the library don't damage the books and, because they're nocturnal, they usually don't bother the human guests. The much bigger danger to the collection is the insect population. Many bug species are known to gnaw on paper, which could be disastrous for the library's rare items that date from before the 19th century. The bats act as a natural form of pest control: At night, they feast on the insects that would otherwise feast on library books.

The Joanina Library is famous for being one of the most architecturally stunning libraries on earth. It was constructed before 1725, but when exactly the bats arrived is unknown. Librarians can say for sure they've been flapping around the halls since at least the 1800s.

Though bats have no reason to go after the materials, there is one threat they pose to the interior: falling feces. Librarians protect against this by covering their 18th-century tables with fabric made from animal skin at night and cleaning the floors of guano every morning.

[h/t Smithsonian]

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The Surprising Role Bats Play in Making Your Margarita
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The next time you have a margarita, raise your glass to the humble bat. Long-nosed bats are the main pollinators of agave, the plant used to make both tequila and mezcal. (Tequila is specifically made from blue agave, or Agave tequilana, while mezcal can be made from any species of the plant.) These agave plants open their flowers at night, attracting bats with their sugary nectar, and in turn, the bats help spread their pollen.

One of those bats, the lesser long-nosed bat, just got off the endangered species list in April 2018, as The Washington Post reported. It's the first bat species ever to recover its population enough to be taken off the Endangered Species List. Its revival is due, in part, to tequila producers along the bat's migration route between Mexico and the southwestern U.S. making their growing methods a little more bat-friendly.

While the relationship between bats and agave might be mutualistic, the one between bats and booze isn't necessarily so. Typical agave production for tequila and mezcal involves harvesting the plant right before it reaches sexual maturity—the flowering stage—because that's when its sugar content peaks, and because after the plant flowers, it dies. Instead of letting the plants reproduce naturally through pollination, farmers plant the clones that grow at the agave plant's base, known as hijuelos. That means fields of agave get razed before bats get the chance to feed off those plants. This method is bad for bats, but it's not great for agave, either; over time, it leads to inbred plants that have lower genetic diversity than their cross-pollinated cousins, ones that require more and more pesticides to keep them healthy.

Rodrigo Medellín, an ecologist who has been nicknamed the "Bat Man of Mexico," has been leading the crusade for bat-friendly tequila for decades, trying to convince tequila producers to let some of just 5 percent of their plants flower. The Tequila Interchange Project—a nonprofit organization made up of tequila producers, scientists, and tequila enthusiasts—led to the release of three bat-friendly agave liquors in the U.S. in 2016: two tequilas, Siembra Valles Ancestral and Tequila Ocho, and a mezcal, Don Mateo de la Sierra.

In 2017, when Medellín and his team visited the agave fields of Don Mateo de la Sierra to gather data, they discovered that the project was even more bat-friendly than they thought. The Mexican long-nosed bat, another endangered species, was also taking its meals at the field's flowering plants.

This weekend, raise a glass of tequila to all the bats out there—just make sure it's a bat-friendly brand.

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