Photo: Courtesy of U.S. Fish and Wildlife Service
White-nose Syndrome (WNS)
White-nose syndrome (WNS) is a fungal disease that is killing several species of bats during hibernation.
Current evidence indicates that the fungus doesn't infect humans.
The name refers to the white fungal growth seen on infected bats’ muzzles and wings. This fungus
(Pseudogymnoascus destructans), is a psychrophilic (cold-loving) fungus which grows in the cold
temperatures found in bat hibernacula (4-20 C). WNS was first identified in February 2006 in the
State of New York and has spread rapidly to 33 States and seven Canadian provinces. In the following
6 years, WNS killed an estimated 6 million bats in North America. Mechanical damage is to the wings,
which are critical for water balance during hibernation, but infection also irritates the skin, which wakes
the bat up, which results in the burning of critical fat reserves, which will eventually kill that bat by
starvation (bats can't replenish these reserves until insects (food) returns in Spring).
The fungus is spread by bats as they fly amongst roosts. Humans can spread the fungus accidentally
by transporting the fungus on shoes and equipment. You can help slow the spread of WNS.
Declines in bat populations directly impact human health since humans depend on bats for important
ecosystem services such as controlling pest insects. The US Forest Service estimated that the die-off
from WNS in one year which means that 2.4 million pounds (1100 tons) of insects will go uneaten.
This becomes a financial burden to farmers estimated to be nearly $3 billion dollars annually.
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West-Nile virus (WNV)
South Dakota's bats feed upon moths, beetles, and other night flying insects, consuming up to half their
body weight in insects each night. Despite their ability to control several different types of pests over
farmland or in your backyard, the truth is that they don't really eat that many mosquitos if they can find
juicier bugs to eat, i.e, their mosquito-meals do not make a big ecological difference - but it is a good start!
The West Nile virus is primarily transmitted by Culex mosquitos, and the primary hosts of this virus are
birds. In the United States, thousands of cases are reported a year, with most occurring in August and
September. The virus is genetically related to Japanese encephalitis and can infect a wide range of
animals who are often asymptomatic. Nearly 20% of infected humans will develop a fever, headache,
vomiting, or a rash. In contrast, the virus is extremely deadly for horses - 40% of those infected die in
in North America.
Between 1999 and 2010, an estimatd 3 million people were infected in the United States. The highest
incidence rates were observed in states of the central great plains, with South Dakota,
Wyoming and
North Dakota leading in incidence.
Climate change will affect both the seasonality and the distribution of mosquitos and this virus.
For now, bats will certainly help, but the best way to reduce mosquito populations is to eliminate
standing pools of water, such as that found in old tires, farm ponds, buckets, and gutters.
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