White Nose Syndrome: A North American Bat Epidemic

bat-silhouette

BY PATRICK MILLER
Staff Writer

When thinking about the state of an agricultural community such as the Eastern Shore, many may not realize bat play an integral part in the lands health.
This ecological balance may be damaged due to an epidemic hitting bats in the area.
Bats, when undergoing hibernation, find a comfortable location in a cave to roost and hang among thousands of their kin, all involved in the same seasonal rest.
The animals have low activity throughout this period as they wait for warmer months when food is aplenty. All that these animals can do is keep their metabolism and heart rate low, hoping to make it to spring.
A threat to hibernating bats has been the discovery of Pseudogymnoascus destructans, a fungus that causes a fatal disease in various species of bats. The affected species are largely Myotis (mouse-eared) bats, a group of small bats including the little brown bat, common to the Eastern Shore environment.
A white discoloration often appears on the muzzle of the bat as well as the ears and wings, giving the subsequent ailment the name, “White Nose Syndrome” (WNS).
The epithelium, which includes both the outside skin and the walls of the respiratory system, is penetrated by the fungus’s small branch-like projections called mycelia.
This fungus is optimized for attacking hibernating bats because the species thrives best in temperatures between four to 20 degrees Celsius, which is a common winter temperature within the caves that bats roost in. In such close quarters, the disease can spread fast between the vulnerable animals and quickly infect an entire population.
There is a trend of relentless migration of this disease from its estimated beginnings in Canada, showing a drop in approximately 80 percent of the Northeastern U.S. bat population.
The United States Geographical Survey (USGS) has confirmed that the disease has spread to central states such as Alabama, Indiana, Kentucky, Tennessee and Missouri, although cases of high mortality have not yet been reported.
Professor Aaron Hogue of the Salisbury University biology department has conducted research on flight patterns of bats on the Eastern Shore. He recognizes the large threat that WNS has on bat populations throughout the country.
“Bats are one of the main predators of nocturnal volant (flying) insects in both natural and artificial ecosystems,” Hogue said. “Any insect that feeds on crops often consumes the fruiting body of the plant, effectively diminishing crop yield. The estimates land somewhere in the billions though it is difficult to be totally accurate.”
These animals are listed as an “insect suppression service” to the agricultural industry, meaning that they are recognized by the government and farmers as ecologically significant consumers of insects. Economic analyses have shown that their service could be valued at as much as $4 billion to $50 billion.
Locally, the disappearance of bats could have large impacts on the crop yields of farms around the Eastern Shore. A variety of beetles and other flying insects are the main attackers of crops in the region, and as the little brown bat population diminishes in number, the economic damage could leave local farmers hurting.
Proceeding into the territory of fighting this disease has proved to be difficult due to the simple nature of ecological impact.
“The problem is that almost all of the solutions that have been proposed have unknown consequences for other species,“ Hogue said. “So if you sprayed a fungicide in the cave ecosystem, you’re probably going to kill off a lot of normal fungi that live there, and then the insects that rely on the fungi get affected.”
Implications such as these are extremely difficult to predict due to so many factors. Specialists say that researching all possible effects of a disease-prevention initiative is crucial to developing a plan that works and takes all consequences into account.
Hogue said that significant funding and mobilization of researching proposed solutions is the best way to proceed.
Recent studies have supported data that bats, throughout their natural history, have gone through large mortality events caused by fungi in Europe, and bat species with genetic resistance in their population’s gene pool were saved by having this trait naturally selected for in their environment.
Hogue’s best guess was that this will end similarly, but the real challenge is keeping harder-hit species, like the Myotis (mouse-eared bat) species, around long enough for resistant bats to help the populations return.
With death tolls skyrocketing well into the millions and bat species hurting tremendously, the implications of WNS are staggering.
The spread of this disease is a threat to North American bats and the massive agricultural industry that is built on the management of insects in both natural and artificial ways. Only time will tell whether the bats will survive this epidemic to allow the populations to recover across the continent.

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