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LOS ANGELES – A mysterious mushroom that has killed millions of bats in the eastern United States and left caves littered with their tiny carcasses has arrived in northern California and appears on the verge of spreading throughout the state, according to officials.
Government biologists confirmed Friday that a number of bats found near the Lassen Volcanic National Park had been tested positive for the causative agent responsible for white nose syndrome – a relatively new disease that leaves a white mark on the muzzle of the infected animal.
The disease, caused by a cold-loving fungus, suddenly appeared in the northeast a little over a decade ago and has gradually shifted to the west. The fungus has devastated bat species from North America in some areas and pushed the natural pest control agents to extinction.
According to Californian biologists, the fungus was detected in four bats perched in homes and in a bank building in the city of Chester, about fifteen kilometers southeast of the park. The first case was detected a year ago and the others much more recently, officials said.
"We all thought we would have more time before we reached this far west," said Winifred Frick, biologist at the University of Santa Cruz and chief scientist at Bat Conservation International. "We should all be very concerned about this heartbreaking discovery."
Since its discovery in New York 12 years ago, the mushroom has swept through 38 states and killed legions of bats. The majority of deaths were small brown bats – one of the most common mammals in North America – but scientists say that most of the 45 species of bats in the United States and Canada may be susceptible to disease. (The fungus is not known to cause disease in humans, according to officials.)
The discovery in northern California was a setback for state and federal efforts to slow the spread of the fungus. These initiatives included restricting human access to caves where tens of thousands of bats winter in hibernation, as well as continuing attempts to develop a vaccine.
"There is no quick fix when it comes to healing," Frick said.
Unlike other areas of the country, where bats congregate in large numbers, California bats tend to congregate in much smaller groups under highway overpasses, on rocky slopes, in attics, and underpasses. the foliage of palms.
Although it is possible that warmer temperatures on the west coast and smaller bat groups are slowing the transmission of the pathogen, there is no reason to think that She will not travel to Southern California, said Jeremy Coleman, National Coordinator of White Nose Syndrome for the US Fish and Wildlife Service.
"We know that bat losses in the West will be less visible than in the Northeast, where thousands of dead bats are scattered in dark, cold caves and across the countryside," said Coleman. "Beyond that, though, there are many critical unknowns. For example, we do not know exactly where the bats are in California or how the disease will eventually manifest in the warmer climate of the state. "
Scott Osborn, National Small Scale Conservation Coordinator for the California Department of Fish and Wildlife, said his agency is making formal requests for funding, staffing and monitoring programs for fight against the pathogen.
"We hope that its repercussions in California will not be as fast and radical as in other parts of the country," Osborn said.
The fungus that causes the white nose syndrome, Pseudogymnoascus destructans or Pd, is partly named because of the destruction it caused to the country's bat population. The fungus digests the skin and the wings of bats in hibernation. It is thought that he is native to Europe, where bats have developed a resistance there.
However, once the fungus arrived in North America, bats had little time to develop immunity before being killed in large numbers.
The disease was first documented in a cave near Albany, New York, and then began to spread westward along the flyways. Initially, the fungus was identified as Geomyces destructans, but it was later determined that it belonged to another genus.
"We knew it was inevitable, but we are dismayed by the speed," said Coleman about the spread of Pd. "I would like it to be science fiction and not reality."
Scientists are struggling to find a solution to the epidemic because bats play a vital ecological role that also benefits humans.
At night, they feast on mosquitoes – some of which transmit West Nile virus – and also devour agricultural pests that damage cotton and maize crops. Recent studies estimate that the value of pest control provided by bats each year is at least $ 3.7 billion nationwide. They also pollinate the agave used to make tequila, as well as the saguaro, a cactus from the state of Arizona.
During this part of the year when there are no insects to eat, bats have to hibernate to survive – and this has allowed the deadly mushroom to flourish. During hibernation, the body temperature of a bat falls into the ideal range for the fungi to grow, while its immune system is inhibited. Infected bats wake up much more often than they should during hibernation and deplete their fat intake that lives for life.
Due to the size of bat colonies and their many interactions – breeding, hibernation, swarming, mother-baby activities – it would only be necessary for an infected bat to trigger a local outbreak.
The fungus can persist in caves for decades, even in the absence of bats. It is usually transmitted by direct contact, but spores can cling to clothing, shoes and caving clothing. Thus, humans can unwittingly transport spores to new places.
Scientists have considered using fungicides to fight the disease, but studies have shown that they could kill other microbes in the caves, possibly triggering a whole series of unexpected consequences. According to these studies, another option – installing heaters in caves – would disrupt the hibernation of bats.
Another plan that was ultimately dismissed as too practical is to use decommissioned military bunkers as artificial hibernators for overwintering bat populations. Temperature-controlled bunkers – which could be decontaminated in summer – would have allowed biologists to monitor their behavior and administer possible treatments for the disease.
A more recent idea that looks promising is to spray a jelly-like vaccine on the skin of hibernating bats. Naturally demanding healers used the medicine as they licked their faces and ears. Officials said it will take several years, however, to develop a viable vaccine.
Ironically, the arrival of white nose syndrome in California comes at a time when local naturalists are becoming more and more aware of chocolate-brown insectivores, the size of a mouse.
Equipped with electronic devices to detect bats, Miguel Ordeñana, expert in mammals at the Natural History Museum of Los Angeles County, recently confirmed the presence of at least five species of bats in the Los Angeles area. He has seen them "fly over all areas of the region, from southern Los Angeles to the San Fernando Valley, through El Segundo and downtown," he said.
The most widespread bat in the Los Angeles area is the Mexican free-tailed bat, named after a quarter-inch tail that extends beyond the edge of the membrane. of his tail. The bat has a wingspan of 8 to 10 inches, flies high and fast and feeds on mites and other insects.
"Judging by the results of my polls, local bats are doing better than expected," Ordeñana said.
But the discovery of the mushroom suddenly added a sense of trepidation to the summer evening "Bats and Brews on the River" strolls along a stretch of the Los Angeles River north of the center. -city. The public events sponsored by the non-profit organization Friends of the Los Angeles River are intended to familiarize participants with the beats of life of bats near their own backyard.
"Our goal is to excite and inspire people about the remarkable creatures that share the airspace above our urban ecosystem every night," said Michael Atkins, spokesperson for the non-profit association. lucrative. "Sadness would have to say that in 10 years, bats were everywhere."
Louis Sahagun is a writer of the Los Angeles Times.
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