Wednesday, June 17, 2015

Surviving White-nose: A New Hope


Fig.1. A Mexican long-tongued bat (Choeronycteris mexicana) feeding at a flower. (Credit: USFWS, 2012)

Nearly 80 percent of all flowering plants and three fourths of food crops are reliant on animal pollinators. Well-known pollinators like bees, butterflies, and moths - as well as more unusual ones like lemurs and geckos - are being celebrated right now for National Pollinator Week, an effort promoted by United States agencies and the nonprofit group Pollinator Partnership. This event is an opportunity for researchers and activists to raise awareness about the importance of pollinators to ecosystems and agriculture, as well as to address precipitous declines in some of these animal species. While many people already know about the disappearance of Monarch butterflies and honeybees, the loss of bats is lesser known and yet has been called North America’s “largest wildlife crisis.”

Bats pollinate more than 300 species of fruit, including mangoes, bananas, guavas, and agave (used to make tequila). Some also act as pest control, which saves an estimated $3.7 billion a year of reduced crop damage and pesticide use in the United States alone. Unfortunately, that estimate might become a very real cost as a devastating disease sweeps across the nation. White-nose Syndrome (WNS) has killed more than 5.7 million bats since its appearance in 2006, with colony mortality rates reaching up to 100 percent at some sites. As scientists scramble to understand the disease, one laboratory found bacteria that might offer bats the key to survival.



Fig.2. This bat is suffering from White-nose Syndrome in Great Smoky Mountains National Park. The white P. destructans fungus can clearly be seen on the bat’s nose. (Credit: USFWS via Flickr, 2012)


Bacteria versus Fungus

The disease is named for the white fungus Pseudogymonascus destructans, which infects the muzzle, ears, and wings of hibernating bats. The fungal growth over the nose and mouth causes the bat to wake up much more frequently than normal during hibernation. Such chronic disturbances burn through their precious fat deposits, starving or freezing the animal before spring. Last May, however, the impossible occurred. A swarm of 150 WNS survivors were released in Hannibal, Missouri.

Georgia State University’s Chris Cornelison, along with colleagues with the U.S. Forest Service, discovered a type of bacteria native to soil that inhibits growth of P. destructans. This bacteria, Rhodococcus rhodochrous, releases volatile organic compounds to create an environment in which the fungus cannot grow. The researchers were able to use these bacterial products to treat diseased bats and found varying rates of recovery among the animals. Although more research is necessary to determine the effectiveness of R. rhodochrous as a possible treatment, it marks the first hope in a very long time that scientists may have found a match for this devastating disease.

Race Against Time

While some researchers work to understand the mechanisms behind WNS, others race to document species that might go extinct. Natural history museums often hold vast collections of bats, which offer insights into anything from species range to zoonotic diseases. The American Museum of Natural History alone holds more than 125,000 bats. Its efforts to understand species diversity as habitats dwindle and WNS spreads are joined by groups such as the Organization for Bat Conservation and Bat Conservation International. These organizations work to overcome cultural stigma about bats and to promote the conservation of these animals. Like other pollinators, bats are a vital part of the world around them and need our protection and care if they are to survive.


If you want to take action and get involved with National Pollinator Week, check out the Pollinator Partnership page for activities and events in your area.



References:

Boyles, J.G., Cryan, P.M., McCracken, G.F., & Kunz, T.H. (2011, April 1). Economic Importance of Bats in Agriculture. Science, 332 (6025): 41-42. DOI: 10.1126/science.1201366.

Griggs, M.B. (2015, May 26). Bacteria Appears to Help Bats Fight Deadly White-nose Syndrome. Popular Science. Retrieved from http://www.popsci.com/treatment-appears-help-bats-stricken-deadly-white-nose-syndrome

Kemp, C. (2015, February 18). Museums: The endangered dead. Nature. Retrieved from http://www.nature.com/news/museums-the-endangered-dead-1.16942

White-nose Syndrome Resources. (n.d.). Bat Conservation International. Retrieved from http://www.batcon.org/resources/for-specific-issues/white-nose-syndrome




Glossary

animal pollinator
A vector that moves pollen from anthers to stigma of a flower to fertilize it.

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