Friday, March 20, 2009

NE Bat Die-Off Spells BIG Trouble for Agriculture

A ProMED-mail post

ProMED-mail is a program of the
International Society for Infectious Diseases

Date: Wed 18 Mar 2009
Source: The Hartford Courant [edited]

Fungus kills about 90 percent of Connecticut's bats
White-nose syndrome, the mysterious plague that is decimating the
Northeast's bats, killed off about 90 percent of Connecticut's bats
over the winter and is now galloping across the country so quickly
that it threatens the nation's -- and probably the world's -- largest
bat populations in the American South.

Jenny Dickson, the Connecticut Department of Environmental Protection
wildlife biologist supervising the detection and control of
white-nose syndrome in the state, said Tuesday [17 Mar 2009] that
visits to 2 sample caves in Litchfield County in the past 2 weeks
revealed veritable bat catacombs. Dickson's team of wildlife experts
found thousands of dead bats floating like dead fish in standing
water, or stacked on top of each other along the flat ledges of the cave walls.

"It was grim, and you don't have to be a scientist to realize the
implications for the environment inside those caves," said Dickson.
"This is a massive, unprecedented die-off, with significant potential
impacts on nature, especially insect control."

Findings by Dickson's counterparts in nearby states paint an even
more dire picture for Connecticut.

Bats are migratory, and most of Connecticut's bats fly there in the
spring from hibernation caves containing hundreds of thousands of
bats in the southern Adirondacks, the lower Hudson Valley, Vermont
and the Berkshires of western Massachusetts. Scientists entering
those caves since February [2009] have found 90 percent to 95 percent
mortality rates, with some caves in New York having death rates
approaching 100 percent. All told, scientists following white-nose
syndrome have calculated that up to a million bats have already died
in the Northeast states.

Scientists say that all bat species are vulnerable to the fungus.
Dickson said Tuesday [17 Mar 2009] that the disease has hit hard
among little brown bats and northern long-eared bats, which are the
ones most commonly seen in Connecticut, but that it has spread to
other species as well.

Combined with the losses of bats that hibernate in Connecticut, the
deaths in neighboring states mean that bats fluttering over evening
barbecues or swooping down to devour insects over cornfields will be
a rare sight this summer.

The syndrome, first discovered in New York state in 2006, is a
condition in which a white fungus coats the heads, legs, and wings of
hibernating bats. To fight the physiological effects of the fungus,
bats deplete their fat reserves before the winter is over, fleeing
from their caves in a desperate search for insects to eat. The
ravenous, emaciated bats are then found lying in the snow or clinging
to the sides of barns, and usually die before enough mosquitoes and
moths hatch for them to eat.

Scientists have not been able to explain why the white fungus
covering the bats, _Geomyces_, appears in the 1st place, but the
impact on the balance of nature is clear. Bats eat an average of more
than 3000 mosquitoes and moths apiece every night. A large die-off of
the species will directly affect activities and industries that rely
on natural insect control -- recreation, dairy farming, and horseback
riding, among others.

Scientists working on white-nose syndrome say that they have detected
no direct health threat to humans. But they do worry about indirect
threats caused by insect-borne diseases, especially after an
especially wet fall and winter that produces favorable conditions for
mosquito breeding. The numbers of cases of such diseases as West Nile
virus have been very low in Connecticut, but scientists do not know
how a larger population of mosquitoes will affect human and animal health.

Dickson said that her team of scientists will be helped by public
reports of bats flying in the daytime during the next 2 weeks, when
there are not enough insects for bats to eat. The telltale white
fungus on the bats will not be present, because it disappears when
exposed to the sun and heat. Reports of daytime sightings, or other
erratic behavior by bats, may be made to the DEP's number, 860-675-8130.

Since it was first detected in New York caves 3 years ago [2006],
white-nose syndrome has crossed state lines, probably carried by
migrating bats themselves. Last year [2008], the range of the plague
had been restricted to the Albany, NY, area and western New England.
But this year [2009] white-nose syndrome has been confirmed from New
Hampshire to southwestern Virginia. The spread of the condition to
Virginia especially concerns scientists.

Crops at risk
Ecologist Merlin Tuttle of Texas is a bat expert and wildlife
photographer who leads the battle to save the endangered gray bat.
"The number of bats that have died so far, which is probably over a
million now, will be dwarfed by what is going to happen in the next
few years," Tuttle said.

"Virginia is right on the border of perhaps the biggest bat
hibernation areas in the world -- Tennessee, Alabama, and Kentucky --
where there are caves with such large populations of bats we can't
even measure how many millions are in there. They spread from this
area across vast ranges of the agricultural South. Mortality rates
like those we are seeing in the states already hit by [white-nose
syndrome] would be devastating for the national bat population."

Studies conducted by Tuttle and other scientists have documented the
huge value that bats deliver to farming and forestry. Every June,
over the vast corn and cotton fields of Texas, for example, millions
of corn earworm moths migrate north from Mexico, descending at dusk
to lay their eggs on crop fields. If left unchecked, these eggs would
hatch within a few weeks, and then new moths would lay additional
eggs, multiplying their scourge and smothering the crops.

Using Doppler radar, radio microphones beamed into the sky and feces
studies of free-tailed bats, scientists have documented that
"high-altitude foraging" by the bats intercepted most of the moths
before they could land on crops, saving millions of acres of cotton
and corn. One study concluded that the free-tail bats -- there are at
least 100 million of them in central Texas -- consume more than 2
million pounds of insects every night.

But this balance-of-nature act is not restricted to Texas. "We have
the same corn, the same earworm moths, the same night-feeding by our
bats right here in Connecticut," said Dickson. "And now that we have
this huge mortality of bats, [white-nose syndrome] could have a
severe impact on our crops, but we just don't know yet."

More need for pesticides
One scenario that worries wildlife scientists is increased use of
pesticides. If farmers see that a crop-eating insect has landed on
their fields, they call in crop-dusting planes or truck-sprayers
right away, which then encourages other farmers to order spraying.
Without enough bats to protect crops, farmers might be tempted this
year [2009] to use more pesticides, a chemical chain-reaction that
can affect people, wildlife, and nearby streams, Tuttle and other experts said.

Even if the cause of white-nose syndrome is identified soon, the
damage to the bat population has already been substantial. "This is a
species that reproduces very slowly and that lives very long for the
wildlife world -- many bats survive for 30 years," Dickson said.
"Each time you lose a bat, you're losing a very precious benefit to
the environment. It will take generations to replenish this bat population."

[Byline: Rinker Buck]

Communicated by:
ProMED-mail Rapporteur Susan Baekeland

[This particular article highlights some rather far reaching
consequences of the loss of bats, which in many ways mirrors the loss
of the bees with colony collapse disorder. These creatures are
exceptionally important.

What the article does not fully address is the threat of increased
use of pesticides to domestic animals. Many farmers turn cattle and
swine into corn stubble fields for grazing and eating of ears of corn
that fell through the harvesting machines. With an increase in
pesticides on the fields this represents another concern as these
animals can be poisoned by the chemicals to eliminate the insects.

Most fungi are opportunistic by nature, and that is part of the
complicating pattern with the bats. What lowered the resistance of
the bats that they are unable to fend off such a fungus? We hope for
answers soon. - Mod.TG

[The article above includes photographs of bats with white-nose
syndrome; they can be seen at
- CopyEd.MJ]

[see also:
White-nose syndrome, bats - USA (06): (PA) RFI 20090311.1011
White-nose syndrome, bats - USA (05): (PA) 20090309.0975
White-nose syndrome, bats - USA (04): (PA) 20090306.0931
White-nose syndrome, bats - USA (03): (WV) susp 20090220.0711
White-nose syndrome, bats - USA (02): (northeast) 20090208.0578
White-nose syndrome, bats - USA: (Northeast) 20090129.0401
White-nose syndrome, bats - USA (07): (Northeast) 20081102.3448
White-nose syndrome, bats - USA (06): (Northeast) 20080331.1195
White-nose syndrome, bats - USA (05): (Northeast) 20080304.0898
White-nose syndrome, bats - USA (04): (Northeast) 20080304.0880
White-nose syndrome, bats - USA (03): 2004 Dorset bat colony gate 20080221.0709
White-nose syndrome, bats - USA (02): (Northeast) 20080220.0687
White-nose syndrome, bats - USA: (Northeast) 20080219.0675]

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