The fungus responsible for the deadly bat disease white-nose syndrome (WNS) has been shown to thrive in cave environments without the presence of bats, a revelation seen as painfully bad news, as it suggests a reintroduction of bat populations to caves wiped out by WNS may not be possible.

Since it was first reported in in New York in 2006, WNS has killed nearly 7 million bats as it spread across North America. Although the flying mammals may make some people uncomfortable, bats are essential to the ecosystems in which they live, capable of eating thousands of insects in a single night and providing plants and crops with natural protection against swarms of hungry bugs.

The pest-control value of bats in the North American economy is estimated to be billions of dollars, according to the University of Akron researchers who conducted the fungus study.

WNS has now spread to 22 US states several Canadian territories. The damage WNS can have on a bat colony in one season is staggering. A population of 800,000 bats in one cave in Vermont was totally wiped out by WNS when it took root there, the researchers said.

The fungus that causes WNS is known as Pseudogymnoascus destructans, which is sometimes abbreviated to Pd.

Writing in the journal PLOS One, University of Akron biologist Hazel Barton and her colleagues report the nutritional source of the Pd fungus has shifted from cave soil to bats, but that it's still capable of thriving on its own without a bat host.

The research revealed the Pd produces several enzymes that permit the fungus to grow in the cave environment and support its development.

"The jump from the environment to the bat has come at the expense of some ability for Pd to grow in the environment, but not entirely," Barton said in a statement, adding that Pd still retains enough function to grow exclusively in caves in the absence of bats.

"The ability of the fungus to grow in caves absent of bats would mean that future attempts to reintroduce bats to caves would be doomed to failure," she said.

Barton said she plans to further research how sustainable the fungus is, which will help determine the future of bats amid the deadly disease.