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In 2006, a caver in upstate New York came across bats with an unusual white substance on their muzzles. By 2008, white nose syndrome (WNS), as it was now known, was reported in caves from Vermont to Virginia and thousands of bats were dying, with mortality rates of over 90% in some caves. The fungus growing on the bats has been indentified as Geomyces destructans, related to other soil fungi that are psychrophilic (=like cold temperatures). Bats with WNS often wake up from hibernation and begin to fly around, searching for food, as their fat reserves are low. This has caused a great deal of alarm as some endangered species of bats are at risk of extinction should they be exposed to the disease. But another worry are the trophic effects to the ecosystem if bats, potent insectivores, disappear in large numbers. One estimate, by the US Forest Service, is that there will be an extra 2.4 million pounds of bugs per year without the bats that have been killed by WNS. That will mean more crop pests and more mosquitoes and other disease vectors.
Read more about Geomyces destructans and white nose syndrome here and here.
Fear of an insect plague is a little disingenuous considering:
ReplyDelete-insects' place at the base of the food chain
-the abundance of insect-eating insects, birds, herps, etc.
-the lack of an insect plague in the face of amphibian extinctions
-etc.
But I appreciate your point as bats do need all the good press they can get.
Cheers
Although it's true that other insectivores may "step up" and fill the gap in the food web left by bats, it's really hard to predict. See this recent paper in Science for some evidence of the profound role of tropical bats, as an example. It is true that mosquitoes are not a large proportion of any bat diet, but again, ripples may be felt and continuing to lose huge numbers of bats is a very sad prospect.
ReplyDeleteThanks for the link; I was hoping you had one.
ReplyDeleteConsidering that many arthropods have seasonal population cycles, I don't give much weight to a ten-week study that measures the short-term effects of the temporary removal of a limiting factor. Conversion of forest to cropland destroys bat and bird habitat but allows invertebrates to thrive (until recently). But there is hardly an insect plague around farms (flies notwithstanding); if anything, insect life is reduced. What I'm saying is, it's a very complicated system that we can't begin to understand, so let's admit propaganda when we use it. It's okay to say we love bats. We don't need to justify it with dubious rationalizing. :-)
I am glad you are featuring this fungi, I have a feeling this newly emerging infectious wildlife disease is going be the hot wildlife diease and conservation topic for the next few years, in a parallel manner to the hot topic that amphibian chytridiomycosis (Bd) has become.
ReplyDeleteThey both share a lot of parallels, such as the biodiversity and important ecological roles played by the afflicted hosts.
There's been an interesting twist in the WNS story. A paper currently in press in the journal Emerging Infectious Diseases indicates that while North American bats are dying from the infectious, European bats on another hand are not affected (link below).
http://www.cdc.gov/eid/content/16/2/pdfs/09-1391.pdf
So is this a parasite-related effect (less virulent strain), or is this a host-related effect (European bats resistant to the fungi)? This is very reminiscent of the situation with amphibian chytrid with hosts that are non-afflicted carriers (African clawed frogs and bullfrogs), or strains that are avirulent to their host (for this I am citing a recent paper in Molecular Ecology which reports a strain of Bd from the Japanese giant salamander which is harmless to its host - link below).
http://www3.interscience.wiley.com/journal/122649428/abstract
It wasn't working for me above, so I believe that second link is also available at http://cobra.lyon.edu/2009_Thomas_21%283%294-9.pdf
ReplyDeleteElizabeth Kolbert wrote about this in a May 2009 New Yorker article about periods of mass extinction. Excerpt:
ReplyDeleteIn 2007, biologist Al Hicks, of the New York State D.E.C., and the National Wildlife Health Center started investigating a series of mysterious bat deaths. Many of the dead bats were discovered with a white substance on their nose, which was cultured and found to be an unidentified fungus. Mentions White-Nose Syndrome (W.N.S.). The writer visited an abandoned mine to study bats with Hicks.
Read more: http://www.newyorker.com/reporting/2009/05/25/090525fa_fact_kolbert#ixzz0d69Wp7Ah
Elizabeth Kolbert, A Reporter at Large, “The Sixth Extinction?,” The New Yorker, May 25, 2009, p. 53
IIIIIIts the end of the world as we know it..!
ReplyDelete