Thursday, October 20, 2011

White-Nose Syndrome Threatens North America's Bats

Threats to biodiversity can come in unconventional packages. Currently, conservation biologists are trying to unravel the mysteries of white-nose syndrome (WNS), a pervasive fungal infection spreading its way through New England’s bat populations (Left, a Little Brown Bat, Myotis lucifugus, infected with WNS). WNS was first documented in Albany, New York in 2006. Since then it has been responsible for the deaths of over a million hibernating bats from 2006-2009 (Blehert et al., 2009, and Sebastien et al., 2011). It remains to be seen if WNS is only a symptom of another disease or is actually the causative agent of mortality. However, the lack of evidence for any other pathogen strongly hints to the deadly power of this fungus, newly christened Geomyces destructans (Sebastien et al., 2011).

G. destructans infects the face, nose, ears, and wings of bats as they hibernate, driving hyphae deep into the cutaneous layer, hair follicles, and sebaceous glands (Blehert et al., 2009). While the physiology of pathogen is not well studied, it is apparent that fungal infection rapidly depletes fat reserves (Blehert et al., 2009). Tactile irritation combined with altering water balance of the bats may cause them to rouse from hibernation too frequently, resulting in decrease in fat reserves and death by starvation (below, a map of WNS occurrence as of 2010) (Sebastien et al., 2011).

It is a mystery where G. destructans comes from, although the fungus has been found in association with European bats without mass mortality (Sebastien et al., 2011). This could make G. destructans a dangerous invasive species, or it is possible that a North American Strain recently evolved a higher virulence (Sebastien et al., 2011). Transmission occurs through bats coming into contact with spores that remain inactive in roost sites.

Despite incomplete knowledge, WNS has such a drastic effect on bat populations that measures to contain and minimize the spread of infection must be taken immediately. Globally, bats play important roles in local ecosystems such as insect consumption, flower pollination, and movement of seeds. Allowing such a disease to go unchecked would be a disaster to North America’s bat diversity; steps must be taken to understand this new phenomenon.

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