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Fungus threatens crucial bat population

Published on January 21, 2011 3:01AM

Last changed on February 18, 2011 8:38AM

Frances Sauter

Frances Sauter


For the Capital Press

The time has come to sound the alarm. A newly emerged epizootic is spreading like wildfire across the continent. Dubbed "white nose syndrome," or WNS, its death rate is close to 100 percent. And its victims are dropping like flies.

Over 1 million North American bats have died over the past four years. The once-prolific little brown bat, Myotis lucifugus, may be extinct within 16 years.

WNS has been confirmed in 14 U.S. states, as far west as Oklahoma, and two Canadian provinces, Ontario and Quebec. It has ranged more than 744 miles and has been found in over 115 hibernacula, which are caves or mines where bats spend the winter. This year, scientists fear it will cross the Rocky Mountains.

WNS is named for the white powdery fungus on the snouts of infected bats. This fungus is Geomyces destructans. It is the only fungal pathogen known to directly invade the skin. It may spread through physical contact during the autumn "bat swarm," a feeding and mating period for bats before they go into hibernation.

When a bat goes into hibernation, its body temperature drops to 33 to 59 degrees Fahrenheit. This is a perfect growing condition for G. destructans, which thrives between 39 and 59 degrees.

G. destructans takes advantage of the hibernating bat's down regulated immune system. During hibernation, there is a concomitant 96 to 98 percent reduction of metabolic rate. It causes evaporative water loss. It disturbs circulation, cutaneous respiration and thermoregulation. It prompts early, unusually frequent arousals. It depletes fat stores. It impairs flight control. It may even induce unbearable itching.

WNS is pure torture.

To be frank, so what?

Bats are crucial to our ecosystem and our economy. No joke. A 2006 study by C.J. Cleveland and colleagues demonstrates the economic impact of Brazilian free-tailed bats -- Tadarida brasiliensis -- in an eight-county region in southcentral Texas. These bats like to eat cotton bollworms, whose larvae destroy cotton crops. The bats' value as pest control was estimated at about $741,000 per year.

Besides, bats are eco-friendly pesticides.

A colony of 150 big brown bats -- Eptesicus fuscus -- can devour 38,000 cucumber beetles, 16,000 June bugs, 19,000 stinkbugs and 50,000 leafhoppers in one summer. It consumes all of these agricultural pests for free.

Bats also have a voracious appetite for disease-transmitting insects. A little brown bat can eat 1,200 mosquitoes in a single night. Mosquito-borne diseases include protozoan diseases like malaria, filarial diseases like dog heartworm and viruses like dengue, encephalitis, yellow fever and West Nile virus.

Without bats, the whole ecosystem could unravel, and our farmers could go bankrupt. In the interest of ourselves, our children and our grandchildren, we must save the bats! Do it for the bats. Do it for humankind.

Frances Sauter is a ninth grader at Lynden High School in Lynden, Wash.


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