White-nose syndrome, a fast-spreading disease that over the past six years has been decimating bats in North America, is caused by the fungus Geomyces destructans, scientists at the USGS National Wildlife Health Center in Madison have proven. Their work provides the first direct evidence that G. destructans is responsible for the disease.

Researchers from the U.S. Geological Survey, CALS and other institutions showed that all little brown bats exposed to G. destructans in their study developed white-nose syndrome while hibernating in captivity.

“Identifying G. destructans as causing the disease will help direct future research toward elucidating what makes the fungus pathogenic, what makes North American bats susceptible—and what environmental factors are important for disease progression and transmission to take place,” says Jeffrey Lorch, who was part of the research team as a forest and wildlife ecology graduate student in the UW–Madison Molecular and Environmental Toxicology Center.

Bat populations in the eastern U.S. have been declining at an alarming rate since 2006, when white-nose syndrome first appeared in New York state—a development of particular concern to the U.S. agricultural industry, which saves billions of dollars in pest control costs each year courtesy of insect-eating bats. Bat declines in the Northeast already have exceeded 80 percent.

As Lorch points out, understanding what causes the disease is a crucial first step in controlling it.