By Dr. Becker
I’m happy to be able to report some hopeful news on the bat conservation front -- specifically, the race to find a cure for a deadly fungus that is wiping out bats by the millions in North America.
Since 2006, white-nose syndrome has been discovered in 26 US states and 5 Canadian provinces. This deadly disease has killed almost every single bat in some locations, and is responsible for one of the sharpest declines in North American wildlife in the past 100 years.
In addition to threatening the very existence of some bat species, white-nose syndrome is also heavily impacting the agricultural industry. That’s because a single bat can eat up to 4,500 insects for dinner each night, which makes bats an invaluable and all-natural method of insect control.
Discovery #1: Naturally-Occurring Bacteria Inhibits Fungus Growth
Scientists at the University of California, Santa Cruz have discovered bacteria that seem to very effectively inhibit the growth of the white-nose syndrome fungus, Pseudogymnoascus destructans, in laboratory tests.1 The bacteria occur naturally on some bats and could be useful in controlling the deadly disease.
Laboratory experiments are underway to determine if treating bats with the bacteria protects them from the disease. If the results are positive, the researchers will next attempt a small field trial.
UC Santa Cruz graduate student Joseph Hoyt took bacteria from the skin of four bat species and tested it for its ability to inhibit the growth of the fungus. Six bacterial isolates (all in the genus Pseudomonas) showed good results and were tested more extensively. All six isolates significantly inhibited growth of the fungus, and two of the six were especially effective in suppressing fungal growth for more than 35 days.
According to Hoyt:
"What's promising is that the bacteria that can inhibit the fungus naturally occur on the skin of bats. These bacteria may just be at too low a level to have an effect on the disease, but augmenting them to higher abundances may provide a beneficial effect.”2
Bacterial Spray Might Protect Hibernating Bats
The UC Santa Cruz scientists are hopeful that a bacterial spray applied to bats while they hibernate might suppress the fungus sufficiently to allow them to survive the winter. The fungus grows on the skin of the noses, ears, and wings of bats during hibernation when their body temperature is lower than normal.
Previous research has shown that the very few bats in colonies besieged by white-nose syndrome who survive the winter can overcome the infection when they emerge from hibernation and their body temperatures increase.3
According to study co-author Marm Kilpatrick of UC Santa Cruz, a wildlife disease expert working with state and federal wildlife agencies to track the spread of white-nose syndrome, four bat species in particular have been decimated by the disease, with some populations decreasing by over 90 percent. And one species, the northern long-eared bat, is headed for extinction.
"Everywhere the disease has been for a couple of years, this bat is gone. We don't have any tools right now to protect this species," says Kilpatrick.4
Discovery #2: Collagen-Eating Enzyme Responsible for Tissue Destruction
Researchers at the University of California, San Francisco and Brown University in Rhode Island have discovered the mechanism by which the white-nose syndrome fungus breaks down tissue in bats. This finding may open the door to potential treatments.5
Pseudogymnoascus destructans (the fungus that causes white-nose syndrome) originated in Europe. It inhabits the cold caves where bats hibernate. European bats have apparently adapted to the fungus, however, North American bats are defenseless against the organism, which is why it is able to break down wing tissue as they hibernate.
According to the research team, the fungus feeds itself through a process called extracellular digestion in which it transfers digestive enzymes to the bats’ wings, and then imports the resulting breakdown products.
Researchers Uncover Compound That Partially Protects Collagen
The scientists identified all the digestive enzymes, and then isolated the one they believed was destroying tissue – an enzyme capable of digesting collagen, which forms the support structure of tissue. They named the collagen-eating enzyme Destructin-1, and began scouring the scientific literature hoping to find a compound that could block the action of the enzyme.
They tested the protease inhibitor chymostatin and discovered that it provided protection for about 75 percent of the collagen. According to the scientists, this finding suggests there are other substances being transferred from the fungus to the bats’ wings that also break down collagen.
The research team plans to test additional compounds to see if a more effective blocker of Destructin-1 exists.
How You Can Help Save Bats
Unfortunately, it’s not yet clear whether these discoveries will be enough to save a substantial number of bats. What is clear is that ecologists may need to employ a variety of tactics to try to protect bat populations from further decimation, including limiting the spread of the fungus across the US, developing new methods for limiting the infection, and supporting bat health.
You can do your part to help save bat populations by taking the following steps:6
- Avoid caves and mines where bats are hibernating during winter.
- Encourage natural bat habitats around your home by reducing outdoor lighting, minimizing tree clearing, and protecting streams and wetlands.
- Adhere to cave closures. Check with your state and federal agencies or a local chapter of the National Speleological Society for the status of caves and caving in your area. Follow the national WNS Decontamination Protocol to clean and disinfect clothes, footwear, and equipment used in caves or mines.
- Talk to your family and friends about the benefits of bats and the fact that white-nose syndrome is decimating entire populations of bats across North America.
- Report unusual bat behavior, such as bats flying during the daytime in late-winter months, or bat deaths, to your state wildlife agency.