The race to stop white-nose syndrome spreading among the continent’s bats
As white-nose syndrome devastates bat populations across North America, biologists are ghting to nd tactics to save them
W “We sort of knew it was coming, but it doesn’t prepare you for the horror show of an affected cave,” says Craig Willis, biology professor and bat researcher at the University of Winnipeg. The “it” is white-nose syndrome, a disease caused by a fungus that grows on the nose, wings and other exposed skin of hibernating bats. The disease dehydrates the creatures, disrupts their torpor and has up to a 99 per cent mortality rate. This past spring, researchers from Willis’s lab recorded its first appearance in a little brown bat hibernaculum in Manitoba. “It was a typical mass mortality event,” he says, “with bats flying out in the snow and carcasses all clustered near the entrance.” The syndrome was first detected in North America in New York state in 2006 and has since spread across eastern North America, with an expansion into Western Canada seemingly inevitable. The estimated death toll is seven million, potentially the most rapid decline of wild mammals ever. “It’s devastating,” says Hugh Broders, biology department chair at the University of Waterloo. But there are grounds for optimism. Researchers have had success in the lab fighting the fungus with chemicals and biological agents akin to antifungal viruses or probiotics. And in January 2018, mycologists at the U.S. Department of Agriculture’s Forest Service reported that the fungus is easily destroyed by exposure to UV light. Subsequent testing on bats has shown promising results. Still, some biologists think recovery of afflicted bats might depend on a few individuals that have survived the onslaught. Some bats may possess heritable traits that help them make it through the winter with the disease. “If they can weather the consequences of being such a small population, they may be able to establish again,” says Broders. “But it’s going to take a long time.” Little brown bats (pictured) are found in every province and territory except Nunavut, and as far south as southern Mexico. The three species most afflicted by white-nose syndrome — little brown, northern long eared and tri-coloured — are endangered in Canada.
In lab tests in early 2018, simple exposure to UV light was shown to kill more than 99 per cent of the white-nose syndrome fungus. Exciting results, but biologists still have to determine if the treatment works on infected bats and how it might be applied in infected hibernacula. One hypothetical approach is setting up motion-activated lights at cave entrances to expose bats to shots of UV as they pass in and out.