Bats and Bananas

In the process of researching my last blog about Bananapocalypse, I discovered a surprising number of uses for banana peels. Did you know that you can remove a splinter, or a wart, by taping the peel over the splinter or wart? Also, rubbing the peel on a bruise helps make it disappear. Banana peels buried around plants that attract aphids will deter the pests from taking up residence. Check out other handy banana peel hints here and here.

I did not know that recent research has discovered, entirely serendipitously, that Volatile Organic Compounds (VOCs) released by a common bacterium can successfully treat White Nose Syndrome (WNS) in bats. The Georgia State University researchers who made this discovery were looking at ways to delay banana ripening, using bacterial VOCs. One of the researchers noticed that bananas exposed to a particular bacterium, R. rhodochrous, didn’t get moldy. Its VOCs have an antifungal property. Chris Cornelison, now a postdoc at Georgia State, made the mental connection between the fungal WNS in bats and the potential to use bacterial fumes to treat it.

WNS is decimating bats

For those of you who aren’t familiar with it, the plague of WNS started decimating insect-eating bat populations in 29 states and five Canadian provinces during the winter of 2007-2008. The culprit in this disease is the cold-loving fungus Pseudogymnoascus destructans. The fungus attacks hibernating bats, causing behaviors such as daytime flights during winter. These behaviors consume fat reserves stored for the hibernation period. Eventually the fungus damages the bats’ wings and causes water and electrolyte loss.

Given the number of bats that overwinter together in caves, the fungus can easily affect thousands of bats. The USGS estimates that up to 80 percent of bats in the northeastern United States have died from WNS. The precipitous decline in bat populations is expected to affect agriculture, since bats eat insects that harm crops. Mr. Best in Show and I used to see bats flying at night around our house out in the middle of nowhere and, occasionally, flying low in our bedroom. For the past five or six years, though, we haven’t seen a bat at all. Very sad.

Could R. rhodochrous kill the fungus in bats?

Cornelison exposed petri dishes of the WNS fungus to fumes from R. rhodochrous and, as he said, “the first exposure seemed too good to be true.” This is great news for groups who’ve studied the fungus, trying to understand disease pathology and transmission. Scientists knew of nothing that could halt the fungus from continuing to spread, beyond advising spelunkers to take care not to carry the fungus between caves. So Cornelison’s discovery offered the first hopeful news in the battle to save the bats.

Enter The Nature Conservancy in Tennessee. They knew they needed to address WNS head-on. The Conservancy and Bat Conservation International decided to cooperate on a study, treating bats in the field with the VOCs generated by R. Rhodochrous. Bats were exposed to the VOCs then placed in a cave to hibernate. When the bats broke hibernation, they had no detectable signs of WNS. Some had so much wing damage that they will live out their lives in a protected environment. The other, healthier bats were moved to a wild cave.

Fruit bat eating banana via YouTube

Will bacterial emissions solve the WNS problem?

Biological control agents often have unintended consequences, where the agent itself becomes a problem. With this in mind, researchers are proceeding carefully with using VOCs in bat caves. One possibility for treating bats and/or their caves would be to expose an entire cave to the gasses, rather than treat individual bats. Before trying this in the wild, researchers have to find out what such exposure would do to cave ecology. And they have to make sure that the VOCs don’t have unexpected deleterious effects on the bats or other animals. So far, though, this treatment looks promising.

This story has a secondary point: the role of serendipity and non-linear thinking in the advancement of science. The researchers wanted to find a way to retard banana ripening. If no one had realized that the R. rhodochrous VOCs had fungicidal effects—if Chris Cornelison didn’t know about WNS in bats—I wouldn’t be writing this blog. A graduate school professor of mine told me that he accidentally found a book that changed the direction of his Ph.D. research, after he’d already spent weeks following references and compiling a bibliography. You just never know, do you?

References

Matt Miller. Bananas to Bats: The Science Behind the First Bats Successfully Treated for White Nose Syndrome. Cool Green Science, May 15, 2015.

U.S. Geological Survey. Disease Information: White Nose Syndrome

Image credit: Little Brown Bat, Wikimedia

Video credit: YouTube