They are fungi, and they arrived in the United States from overseas with an assist from humans — through travel and trade. They prefer cold conditions and kill with precision, so efficiently that they’re creating a crisis in the wild.
The death toll among amphibians, bats and snakes from fungi represents “potential extinction events,” said Coleman, a U.S. Fish and Wildlife research biologist who coordinates the government’s response to the bat-killing infection known as white-nose syndrome. It’s so large, he said, that it can’t be measured “as far as numbers of dead organisms” and is “decimating populations as we know them.”
Together with a little-
understood disease that is destroying honeybees, the mass die-offs are a huge concern. “We anticipate there will be direct impacts with the loss of so many animals on a massive scale,” Coleman said.
Honeybees pollinate crops, and bats eat billions of pests that ruin them. Frogs and other amphibians help researchers find medical cures, and snakes eat tick-infested rodents that spread Lyme disease. But with little public and private funding, scientists are almost powerless to stop the plague.
“The field of fungal research is small, underfunded and often totally overlooked relative to its importance in the environment,’’ said Arturo Casadevall, a professor and chairman of microbiology and immunology at Albert Einstein College of Medicine in New York. “To my knowledge, there are no successful precedents for the control of fungal pathogens in the wild.”
The pathogens wiping out 10 species of bats, including 93 percent of little brown bats in the Northeast, and at least six snake species in nine states, such as the pygmy rattlesnake and common rat snake, may have been around for decades.
But they have been mostly overlooked until recently, because “they’re affecting wildlife that do not have a direct agricultural or human health impact” — unlike swine flu — “so they fall outside the traditional model of disease response,” Coleman said.
As the threat grows, federal and state officials are beginning to coordinate teams of scientists trying to stop it. In addition to working on the response to white-nose syndrome, Coleman is leading the effort to arrest the progress of the fungus affecting snakes.
Fish and Wildlife was directed by Congress to pursue white nose and other fungi, but was not provided with funding for staff.
“We’re tracking these killer fungi, and we’re trying to respond to them on a landscape of low interest and low budget,” Coleman said.
Not all fungi are bad; many are used in medicine, some help the environment, others are tasty. But some go rogue and become deadly. Fungi are killing numerous plants and trees in addition to animals.
Researchers have a simple theory about how the bat and snake fungi reached the United States: They were brought in by humans through travel and trade. But they’re not sure why it appears that some have become lethal.
After the bat fungus was somehow brought from Europe, possibly in the 2000s, a weird thing happened. For unknown reasons, it morphed into a stalker and killer of bats hibernating in Northeast caves.
“One idea is the environment is changing through climate change in a way that’s making the disease more severe,” said David Blehert, a microbiologist for the U.S. Geological Survey National Wildlife Health Center in Madison, Wis. “Some of the work we have done has been to go into caves and figure out how this fungus . . . kills bats when they’ve coexisted with other fungus in caves for millions of years.”
As many as 7 million bats have died, according to a U.S. Fish and Wildlife estimate last year. Many were discovered in ugly death throes outside caves.
Since its discovery in Upstate New York seven years ago, bats have spread white-nose syndrome north to Vermont, as far south as Georgia and west to Oklahoma.
About $40 million has been spent for white-nose research through last year. Although scientists better understand the fungus, they don’t know how to arrest its growth.
Bats, which eat pests that plague crops and mosquitoes that bite humans, are due to fly back into caves for their annual hibernation next month.
White nose for serpents
The snake fungus is being called white nose for serpents. First reported sporadically in the 1990s, it is now widely seen. Lesions jut from curves and cover the heads of snakes.
Snake fungus spreads more slowly than white nose, because snakes “don’t move as widely as bats,” Emily Boedecker, acting state director for the Nature Conservancy in Vermont, said in the group’s blog, Cool Green Science.
“But they do share some habits,” she said, such as hibernating in underground dens — often with other snake species. Like bats, their immune systems are suppressed in hibernation, when the fungus prefers to attack.
“There has been a lot of money spent on white-nose syndrome . . . but so far they’ve been unable to stop the spread in bats. Snakes are even less appreciated by the public than bats.”
The amphibian killer Chytridiomycosis — chytrid for short — is thought to have come to America in the 1930s with frogs used in pregnancy tests. In a process that could take hours, a woman’s urine was injected into female African clawed frogs. If the frog ovulated, the woman was probably pregnant.
Some frogs escaped or were released. In the late 1990s, clusters of dead frogs in Australia were found to be infected, and in the past decade, infections were found in the United States.
One-third of the world’s amphibians could be lost. The problem is so dire that public and private donors, including zoos and conservation groups, established an Amphibian Ark to preserve the animals and raise awareness of their demise.
According to the Ark, 165 species are believed to have vanished, including 39 species that are “known to be extinct in the wild but still survive in captivity.”
Danger to honeybees
Compared with the threats to bats, snakes and frogs, the danger to honeybees has gotten more funding because bee pollination creates $15 billion per year in added crop value, according to the U.S. Department of Agriculture.
From 2008 to 2012, federal and state officials spent nearly $20 million to update research facilities, conduct more studies into the colony-collapse disorder killing the honeybees and take steps to protect them.
In spite of that, “survivorship of honey bee colonies is too low for us to be confident in our ability to meet the pollination demands of U.S. agricultural crops,” according to a report last year by the USDA National Honey Bee Health Steering Committee.
Six million honeybee colonies existed in 1947; about 2.5 million exist today, vanishing at a rate of about 30 percent per year, the report said.
The disorder’s cause is unknown, though some biologists blame fungi, disease and parasites. Scientists in the European Union pointed to insecticides, but the USDA rejected that theory, saying it was a combination of factors.
“They’re feeding on crops treated with pesticides,” Blehert said, but that it is just one piece of a “complex problem involving different dynamics.”