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Diseases vary among and within species but the causes of this variation can be unclear. Immune responses are an important driver of disease variation, but mechanisms on how the body resists pathogen establishment before activation of immune responses are understudied. Skin surfaces of mammals are the first line of defense against abiotic stressors and pathogens, and skin attributes such as pH, microbiomes, and lipids influence disease outcomes. Sebaceous glands produce sebum composed of multiple types of lipids with species-specific compositions. Sebum affects skin barrier function by contributing to minimizing water loss, supporting thermoregulation, protecting against pathogens, and preventing UV-induced damage. Sebum also affects skin microbiome composition both via its antimicrobial properties, and by providing potential nutrient sources. Intra- and interspecific variation in sebum composition influences skin disease outcomes in humans and domestic mammal species but is not well-characterized in wildlife. We synthesized knowledge on sebum function in mammals in relation to skin diseases and the skin microbiome. We found that sebum composition was described for only 29 live, wild mammalian species. Sebum is important in dermatophilosis, various forms of dermatitis, demodicosis, and potentially white-nose syndrome. Sebum composition likely affects disease susceptibility, as lipid components can have antimicrobial functions against specific pathogens. It is unclear why sebum composition is species-specific, but both phylogeny and environmental effects may drive differences. Our review illustrates the role of mammal sebum function and influence on skin microbes in the context of skin diseases, providing a baseline for future studies to elucidate mechanisms of disease resistance beyond immune responses. [ABSTRACT FROM AUTHOR]

Abstract: Two species of Leuconeurospora, Leuconeurospora capsici (J.F.H. Beyma) Malloch, Sigler & Hambleton and Leuconeurospora polypaeciloides Malloch, Sigler & Hambleton (Ascomycota: Pseudeurotiaceae), are reported from the fur and skin of [...]

We provide a review of fungi, yeasts, and slime molds that have been found in natural solution caves and mines worldwide. Such habitats provide frequent roost sites for bats, and in eastern North America the environmental conditions that support white-nose syndrome, a lethal fungal disease currently devastating bat populations. A list of 1029 species of fungi, slime moulds, and yeasts in 518 genera have been documented from caves and mines worldwide in 225 articles. Ascomycota dominate the cave environment. Most research has been conducted in temperate climates, especially in Europe. A mean of 17.9±24.4SD fungal species are reported per study. Questions remain about the origin and ecological roles of fungi in caves, and which, if any, are cave-specialists. In the northern hemisphere, caves are generally characterized by relatively stable, low temperatures and a lack of organic substrates. This environment favors communities of oligotrophic, psychrotolerant fungi. Data that may help explain how cave environmental features and faunas inf luence the introduction and transmission of cave fungi remains scant.

White-Nose Syndrome is an ongoing fungal epizootic caused by epidermal infections of the fungus, Pseudogymnoascus destructans (P. destructans), affecting hibernating bat species in North America. Emerging early in 2006 in New York State, infections of P. destructans have spread to 38 US States and seven Canadian Provinces. Since then, clonal isolates of P. destructans have accumulated genotypic and phenotypic variations in North America. Using microsatellite and single nucleotide polymorphism markers, we investigated the population structure and genetic relationships among P. destructans isolates from diverse regions in North America to understand its pattern of spread, and to test hypotheses about factors that contribute to transmission. We found limited support for genetic isolation of P. destructans populations by geographic distance, and instead identified evidence for gene flow among geographic regions. Interestingly, allelic association tests revealed evidence for recombination in the North American P. destructans population. Our landscape genetic analyses revealed that the population structure of P. destructans in North America was significantly influenced by anthropogenic impacts on the landscape. Our results have important implications for understanding the mechanism(s) of P. destructans spread. [ABSTRACT FROM AUTHOR]

We document white‐nose syndrome (WNS), a lethal disease of bats caused by the fungus Pseudogymnoascus destructans (Pd), and hibernacula microclimate in New Brunswick, Canada. Our study area represents a more northern region than is common for hibernacula microclimate investigations, providing insight as to how WNS may impact bats at higher latitudes. To determine the impact of the March 2011 arrival of Pd in New Brunswick and the role of hibernacula microclimate on overwintering bat mortality, we surveyed bat numbers at hibernacula twice a year from 2009 to 2015. We also collected data from iButton temperature loggers deployed at all sites and data from HOBO temperature and humidity loggers at three sites. Bat species found in New Brunswick hibernacula include Myotis lucifugus (Little Brown Bat) and M. septentrionalis (Northern Long‐eared Bat), with small numbers of Perimyotis subflavus (Tricolored Bat). All known hibernacula in the province were Pd‐positive with WNS‐positive bats by winter 2013. A 99% decrease in the overwintering bat population in New Brunswick was observed between 2011 and 2015. We did not observe P. subflavus during surveys 2013–2015 and the species appears to be extirpated from these sites. Bats did not appear to choose hibernacula based on winter temperatures, but dark zone (zone where no light penetrates) winter temperatures did not differ among our study sites. Winter dark zone temperatures were warmer and less variable than entrance or above ground temperatures. We observed visible Pd growth on hibernating bats in New Brunswick during early winter surveys (November), even though hibernacula temperatures were colder than optimum for in vitro Pd growth. This suggests that cold hibernacula temperatures encountered near the apparent northern range limit for Pd do not sufficiently slow fungal growth to prevent the onset of WNS and associated bat mortality over the winter. [ABSTRACT FROM AUTHOR]

Skin is a key aspect of the immune system in the defence against pathogens. Skin pH regulates the activity of enzymes produced both by hosts and by microbes on host skin, thus implicating pH in disease susceptibility. Skin pH varies inter- and intra-specifically and is influenced by a variety of intrinsic and extrinsic variables. Increased skin alkalinity is associated with a predisposition to cutaneous infections in humans and dogs, and inter-specific and inter-individual variation in skin pH is implicated in differential susceptibility to some skin diseases. The cutaneous pH of bats has not been characterized but is postulated to play a role in susceptibility to white-nose syndrome (WNS), a fungal infection that has decimated several Nearctic bat species. We used non-invasive probes to measure the pH of bat flight membranes in five species with differing susceptibility to WNS. Skin pH ranged from 4.67 to 8.59 and varied among bat species, geographic locations, body parts, age classes, sexes and seasons. Wild Eptesicus fuscus were consistently more acidic than wild Myotis lucifugus, Myotis leibii and Perimyotis subflavus. Juvenile bats had more acidic skin than adults during maternity season but did not differ during swarming. Male M. lucifugus were more acidic than females during maternity season, yet this trend reversed during swarming. Bat skin was more acidic in summer compared to winter, a pattern also reported in humans. Skin pH was more acidic in captive than wild E. fuscus , suggesting environmental impacts on skin pH. The pH of roosting substrates affects skin pH in captive bats and may partially explain seasonal patterns in wild bats that use different roost types across seasons. Future research on the influence of pH on microbial pathogenic factors and skin barrier function may provide valuable insights on new therapeutic targets for treating bat skin conditions. [ABSTRACT FROM AUTHOR]

With the exception of recent work on bats, no reports on the fungi present on live mammals in underground habitats have been published. We cultured psychrotolerant fungi from the external surface and faeces of live Deer Mice (Peromyscus maniculatus), and from the intestinal contents of a single freshly killed P. maniculatus, overwintering in a white-nose syndrome positive bat hibemaculum and from adjacent summer forest in eastern Canada. A low diversity of psychrotolerant fungi was cultured from P. maniculatus compared with that found in previous studies of the mycoflora of bats and arthropods occupying bat hibernacula in the region. Although the grooming habits of P. maniculatus may reduce the accumulation of a diverse psychrotolerant fungal assemblage on their external surface, we demonstrate that active euthermic mammals in underground habitats can carry viable spores of psychrotolerant fungi, both externally and internally. Small rodents using cave habitats may also play a role in dispersing psychrotolerant fungi between caves and suitable low-temperature habitats (i.e., burrows) in adjacent forest. [ABSTRACT FROM AUTHOR]

White-nose syndrome is one of the most lethal wildlife diseases, killing over 5 million North American bats since it was first reported in 2006. The causal agent of the disease is a psychrophilic filamentous fungus, Pseudogymnoascus destructans. The fungus is widely distributed in North America and Europe and has recently been found in some parts of Asia, but interestingly, no mass mortality is observed in European or Asian bats. Here we report a novel double-stranded RNA virus found in North American isolates of the fungus and show that the virus can be used as a tool to study the epidemiology of White-nose syndrome. The virus, termed Pseudogymnoascus destructans partitivirus-pa, contains 2 genomic segments, dsRNA 1 and dsRNA 2 of 1.76 kbp and 1.59 kbp respectively, each possessing a single open reading frame, and forms isometric particles approximately 30 nm in diameter, characteristic of the genus Gammapartitivirus in the family Partitiviridae. Phylogenetic analysis revealed that the virus is closely related to Penicillium stoloniferum virus S. We were able to cure P. destructans of the virus by treating fungal cultures with polyethylene glycol. Examination of 62 isolates of P. destructans including 35 from United States, 10 from Canada and 17 from Europe showed virus infection only in North American isolates of the fungus. Bayesian phylogenetic analysis using nucleotide sequences of the viral coat protein geographically clustered North American isolates indicating fungal spread followed by local adaptation of P. destructans in different regions of the United States and Canada. This is the first demonstration that a mycovirus potentially can be used to study fungal disease epidemiology. [ABSTRACT FROM AUTHOR]

The biogeography of cave fungi and factors that influence community composition are poorly known. The movement of animals into caves from the outside environment is thought to be one factor that affects cave mycota. Islands often have different faunal assemblages from the mainland, and this may affect the fungal diversity of island caves. In 2014 we swabbed walls in three natural solution caves on Anticosti Island, Quebec, to determine the composition of cave fungal assemblages present relative to well-studied nearby mainland sites. At least one of these caves, Grotte à la Patate in Anticosti National Park, appears to support overwintering bats. Culture-dependent methods were used to establish pure cultures, and fungi were identified by a combination of morphology and genetic sequencing. A total of 54 fungal taxa were identified, with a mean of 7.4 ± 3.9 taxa per swab. The most common taxa isolated were Penicillium spp., Pseudogymnoascus pannorum sensu lato, P. roseus, Trichoderma sp., Cladosporium spp., Thysanophora spp., Mucor sp., and Trichosporon dulcitum. Pseudogymnoascus destructans (Pd), the causative agent of the fungal disease white-nose syndrome in bats, was not detected, and we conclude that Pd was not present in the three sampled caves as of summer 2014. Two of the caves did not appear to be suitable bat hibernacula based on microclimate, although diverse fungal assemblages were detected on the walls. Several other fungal taxa common to bat hibernacula on the mainland, in addition to Pd, were lacking from Anticosti Island caves. We suggest that fungal assemblages on Anticosti Island are influenced by the absence of non-volant cave-visiting mammals on the island, particularly porcupines (Erethizon dorsatum) and raccoons (Procyon lotor), both frequent cave associates elsewhere in Maritime Canada. [ABSTRACT FROM AUTHOR]

Pseudogymnoascus destructans (Pd) causes the fungal disease white-nose syndrome (WNS), which has led to high mortality in some hibernating bat species in eastern North America. The ability to detect viable Pd in hibernacula is important for understanding the role the environment plays as a reservoir for infectious Pd. Previous studies have generally used the high-sugar medium Sabouraud-dextrose (SAB) and have had low yields of viable Pd from environmental samples of Pd-positive hibernacula. While cultureindependent methods (i.e., molecular genetics) have previously shown much better success in detecting Pd, these methods cannot determine viability. In 2012 and 2015, we swabbed walls in four hibernacula with WNS-positive bats in New Brunswick, Canada, and cultured the samples using dextrose-peptone-yeast extract agar (DPYA), SAB, and Malt extract (MEA) media. Samples cultured on DPYA produced viable Pd 43.7 to 50.0% more frequently than SAB, with a maximum overall return for DPYA among sites of 62.5% Pd-positive samples over both years. During the initial outbreak of WNS in our study region, Pd-positive swabs were produced from 40.0 to 83.3% of samples on DPYA, whereas SAB produced a maximum of 40.0%. At one site we detected Pd from 83.3% of swabs cultured on DPYA and 0% on SAB. MEA produced no viable Pd. Our figures for Pd detection are as high as or higher than previously published culture-independent methods, while also confirming the viability of the Pd present. We found that the yield of viable Pd from hibernacula walls decreased from 2012 to 2015 as the hibernating bat population decreased due to WNS mortality, but patterns varied amongst hibernacula, and overall, were not statistically different. It is possible that environmental growth of Pd contributes to its persistence within hibernacula. We suggest that future studies on the environmental persistence of viable Pd discontinue the use of high-sugar media that lack inhibitory fungal growth ingredients, such as SAB and MEA, as they favor fast-growing fungal species that overgrow and mask slowergrowing fungi such as Pd. [ABSTRACT FROM AUTHOR]

Big brown bats ( Eptesicus fuscus) overwintering outside the underground environment are not believed to play a role in the epidemiology of the disease white-nose syndrome (WNS), caused by the fungus Pseudogymnoascus destructans ( Pd). Using quantitative real-time PCR (qPCR), we provide molecular evidence for Pd on four big brown bats overwintering in heated buildings in New Brunswick, Canada. Two of the affected individuals also had very mild, focal, pustular, fungal dermatitis identified microscopically. A third bat, which was qPCR Pd-negative, had similar fungal lesions. Despite determining that these fungal lesions were caused by a suspected ascomycete, the intralesional fungi were not confirmed to be Pd. These findings demonstrate that bats overwintering in heated buildings and other above-ground sites may have subclinical or preclinical WNS, or be contaminated with Pd, and could play a role in local dispersal of Pd. Our inability to determine if the ascomycetes causing pustular lesions were Pd highlights the need for ancillary diagnostic tests, such as in situ hybridization or immunohistochemistry, so that Pd can be detected directly within a lesion. As the host-pathogen relationship for Pd evolves, and where bat species are exposed to the fungus under varying temperature regimes, lesions may become less stereotypic and such tests could help define these changes. [ABSTRACT FROM AUTHOR]

The introduction of Pseudogymnoascus destructans (Pd) to North America, agent of white-nose syndrome in hibernating bats, has increased interest in fungi from underground habitats. While bats are assumed to be the main vector transmitting Pd cave-to-cave, the role of other fauna is unexplored. We documented the fungi associated with over-wintering arthropods in Pd-positive hibernacula, including sites where bats had been recently extirpated or near-extirpated, to determine if arthropods carried Pd, and to compare fungal assemblages on arthropods to bats. We isolated 87 fungal taxa in 64 genera from arthropods. Viable Pd was cultured from 15.3% of arthropods, most frequently from harvestmen (Nelima elegans). Fungal assemblages on arthropods were similar to those on bats. The different fungal assemblages documented among arthropods may be due to divergent patterns of movement, aggregation, feeding, or other factors. While it is unlikely that arthropods play a major role in the transmission dynamics of Pd, we demonstrate that arthropods may carry viable Pd spores and therefore have the potential to transport Pd, either naturally or anthropogenically, within or among hibernacula. This underlines the need for those entering hibernacula to observe decontamination procedures and for such procedures to evolve as our understanding of potential mechanisms of Pd dispersal improve. [ABSTRACT FROM AUTHOR]

The introduction of the fungal pathogen Pseudogymnoascus destructans (Pd) to North America has stimulated research on the poorly known mycology of caves. It is possible that the introduction of Pd reduces the diversity of fungi associated with bats hibernating in caves. To test this hypothesis we examined the fungal assemblages associated with hibernating bats (Myotis spp.) pre- and post- white-nose syndrome (WNS) infection in eastern Canada using culture-dependent methods. We found the mean number of fungal taxa isolated from bats/ hibernaculum was not significantly different between pre-infection (29.6 ± 6.1SD) and postinfection with WNS (32.4 ± 4.3). Although the number of fungal taxa per bat was significantly higher on Myotis lucifugus vs. M. septentrionalis, evidence suggests that this is a reflection of environmental features of individual hibernacula, rather than any biological difference between bat species. The composition and number of the most common and widespread fungal taxa on hibernating Myotis spp. did not change with the introduction of Pd to hibernacula. We found no evidence to suggest that Pd interacts with other fungi on the external surface of bats in hibernacula, even among fungal species of the same genus. However, our data do suggest that environmental characteristics of individual caves can have a significant influence on the fungal assemblages cultured from hibernating bats at specific hibernacula. Following the mortality of thousands of WNS-infected Myotis spp. in one hibernacula, we found that those fungal taxa growing on dead bats were cultured with increased frequency from live bats. This suggests that fungal assemblages on live bats may be sensitive to sporadic introductions of new fungal substrates to hibernacula. [ABSTRACT FROM AUTHOR]

The tricolored bat (Perimyotis subflavus) is threatened by white-nose syndrome (WNS), a fungal disease caused by Pseudogymnoascus destructans (Pd) and was recently ranked as endangered under the Canadian Species-at-Risk Act. There have been few prior studies on the fungi associated with over-wintering bats. Such information is important in assessing overall fungal diversity within the cave habitat, in determining the ecological role that bats may play as dispersers of fungi, and in the identification of fungal species potentially antagonistic to Pd. We swabbed twenty-two P. subflavus overwintering in caves and mines in New Brunswick, Canada, in 2012 and 2013. This produced 408 isolates comprising 60 taxa in 49 fungal genera with an average of 10.2 ± 3.9SD fungal taxa recorded per bat. We found fungal assemblages on P. subflavus (post- WNS) very similar to those we cultured previously from Myotis spp. (pre-WNS) at the same sites. We suggest that the variation in fungal assemblages observed from site-to-site on hibernating P. subflavus is largely due to environmental and ecological characteristics of individual caves, rather than the presence of Pd or roosting habits. [ABSTRACT FROM AUTHOR]

Pseudogymnoascus destructans is the causative agent of an emerging infectious disease that threatens populations of several North American bat species. The fungal disease was first observed in 2006 and has since caused the death of nearly six million bats. The disease, commonly known as white-nose syndrome, is characterized by a cutaneous infection with P. destructans causing erosions and ulcers in the skin of nose, ears and/or wings of bats. Previous studies based on sequences from eight loci have found that isolates of P. destructans from bats in the US all belong to one multilocus genotype. Using the same multilocus sequence typing method, we found that isolates from eastern and central Canada also had the same genotype as those from the US, consistent with the clonal expansion of P. destructans into Canada. However, our PCR fingerprinting revealed that among the 112 North American isolates we analyzed, three, all from Canada, showed minor genetic variation. Furthermore, we found significant variations among isolates in mycelial growth rate; the production of mycelial exudates; and pigment production and diffusion into agar media. These phenotypic differences were influenced by culture medium and incubation temperature, indicating significant variation in environmental condition - dependent phenotypic expression among isolates of the clonal P. destructans genotype in North America. [ABSTRACT FROM AUTHOR]

I Conserv Physiol i 9(1): coab088; doi: 10.1093/conphys/coab088 In the originally published version of this manuscript, the incorrect Supplementary Material was included. The publisher apologizes for the error. [Extracted from the article]

Information on bat populations and hibernacula is important for understanding the impacts of white-nose syndrome (WNS), a fatal fungal disease of bats. Estimates of bat populations prior to the outbreak of white-nose syndrome are presented for 2009-2011 for the most significant bat hibernacula known in New Brunswick. At one of these sites we recorded a major mortality event from white-nose syndrome, the first in the Maritime provinces, late in the winter of 2011. Winter surveys of hibernating bats suggest that a minimum of 7 000 bats overwintered in these hibernacula prior to the outbreak of white-nose syndrome in New Brunswick. The majority of hibernating bats in New Brunswick caves are Myotis lucifugus (Little Brown Myotis) and M. septentrionalis (Northern Myotis), with low numbers of Perimyotis subflavus (Tricolored Bat). The New Brunswick hibernacula that support the greatest numbers of overwintering bats have little temperature variation, winter dark zone temperatures averaging 4--5°C, and minimum dark zone temperatures dropping to no lower than 3.1°C. New Brunswick caves with these temperature patterns characteristically have >140 m of main passage and lack both running water and multiple entrances. Few cave sites in the province meet these criteria, and the known winter bat population appears to be smaller than the summer population. Many bats present during the summer in New Brunswick either hibernate in unknown locations in the province or migrate out of the province to locate suitable hibernacula. Such movements may have hastened the arrival of white-nose syndrome in New Brunswick. [ABSTRACT FROM AUTHOR]

Across their range, Raccoons (Procyon lotor) will opportunistically exploit bats (Chiroptera) roosting in caves as a source of food. During a significant mortality event associated with white-nose syndrome (WNS) at a cave in eastern Canada, we estimate that Raccoons consumed 3 169-3827 dead and dying Little Brown Bats (Myotis lucifugus) and Northern Long-eared Bats (M. septentrionalis) infected with white-nose syndrome, equivalent to 62.0-74.9% of the total bat mortality at this site. However, the generally small dispersal distances of Raccoons and their reduced activity during the period when bats are hibernating suggest that Raccoons are likely not a significant vector for moving the fungus associated with white-nose syndrome, Geoniyces destructans, between most caves at this latitude. Nevertheless, since we show that significant numbers of bats can be consumed in hibernacula through opportunistic feeding by Raccoons, estimates of in-cave mortality due to white-nose syndronie should incorporate any evidence of consumption of bats by Raccoons and other predators. [ABSTRACT FROM AUTHOR]

We provide the first analysis of the fungi associated with a very special habitat, the aeroponic roots found in caves and mines in New Brunswick, Canada. Fungal diversity was assessed by Illumina sequencing using three complementary primer sets targeting ribosomal RNA genes, and roots were identified using the non-coding trnH - psbA spacer. Early colonizing ectomycorrhizal fungi such as Agaricales, Helotiales, Pezizales, and Thelephorales were predominant. Saprotrophs, endophytes and plant pathogens were also present, but Glomeromycota (arbuscular mycorrhizal fungi) were not detected. Fungal root communities were generally most similar within sites. Fungal diversity was inversely correlated with winter dark zone temperatures and distance from the entrance. By using a combination of three primer sets, we detected more fungal taxa than with any one primer set. This study adds to the understanding of these subterranean ecosystems and suggests that future studies investigate factors limiting the presence of late-stage ectomycorrhizal fungi and Glomeromycota. • We provide a first analysis of fungi associated with aeroponic roots in caves and mines. • We detected ectomycorrhizal fungi, endophytes, saprotrophs and plant pathogens. • Late-stage ectomycorrhizal fungi and arbuscular mycorrhizal fungi were not found. • Similarity of fungal communities was related more to site than host or proximity. • Combining three NGS primer sets detected more fungi than any single primer set. [ABSTRACT FROM AUTHOR]

Studies of fungi in caves have become increasingly important with the advent of white-nose syndrome (WNS), a disease caused by the invasive fungus Pseudogymnoascus destructans (Pd) that has killed an estimated 6.5 million North American bats. We swabbed cave walls in New Brunswick, Canada, in 2012 and 2015 to determine whether the culturable fungal assemblage on cave walls changed after the introduction of Pd and subsequent decrease in hibernating bat populations. We also compared fungal assemblages on cave walls to previous studies on the fungal assemblages of arthropods and hibernating bats in the same sites. The fungal diversity of bats and cave walls was more similar than on arthropods. The diversity and composition of fungal assemblages on cave walls was significantly different among media types and sites but did not differ over time. Therefore, no change in the culturable fungal assemblage present on cave walls was detected with the introduction of Pd and subsequent disappearance of the hibernating bat population over a 3-year period. This suggests that fungi documented in caves in the region prior to the outbreak of Pd do not require regular transmission of spores by bats to maintain fungal diversity at these sites. [ABSTRACT FROM AUTHOR]

Wildlife are exposed to neurotoxic mercury at locations distant from anthropogenic emission sources because of long-range atmospheric transport of this metal. In this study, mercury bioaccumulation in insectivorous bat species (Mammalia: Chiroptera) was investigated on a broad geographic scale in Canada. Fur was analyzed (n = 1178) for total mercury from 43 locations spanning 20° latitude and 77° longitude. Total mercury and methylmercury concentrations in fur were positively correlated with concentrations in internal tissues (brain, liver, kidney) for a small subset (n = 21) of little brown bats ( Myotis lucifugus ) and big brown bats ( Eptesicus fuscus ), validating the use of fur to indicate internal mercury exposure. Brain methylmercury concentrations were approximately 10% of total mercury concentrations in fur. Three bat species were mainly collected (little brown bats, big brown bats, and northern long-eared bats [ M. septentrionalis ]), with little brown bats having lower total mercury concentrations in their fur than the other two species at sites where both species were sampled. On average, juvenile bats had lower total mercury concentrations than adults but no differences were found between males and females of a species. Combining our dataset with previously published data for eastern Canada, median total mercury concentrations in fur of little brown bats ranged from 0.88–12.78 μg/g among 11 provinces and territories. Highest concentrations were found in eastern Canada where bats are most endangered from introduced disease. Model estimates of atmospheric mercury deposition indicated that eastern Canada was exposed to greater mercury deposition than central and western sites. Further, mean total mercury concentrations in fur of adult little brown bats were positively correlated with site-specific estimates of atmospheric mercury deposition. This study provides the largest geographic coverage of mercury measurements in bats to date and indicates that atmospheric mercury deposition is important in determining spatial patterns of mercury accumulation in a mammalian species. [ABSTRACT FROM AUTHOR]

White-nose syndrome (WNS), a fungal disease that has caused catastrophic population declines of bats in eastern North America, is rapidly spreading across the continent and now threatens previously unexposed bat species in western North America. The causal agent of WNS, the fungus Pseudogymnoascus destructans, can infect many species of hibernating bats, but susceptibility to WNS varies by host species. We previously reported that certain traits of the skin microbiome, particularly yeast diversity and abundance, of bat species in eastern North America are strongly associated with resistance to WNS. Using these traits, we developed models to predict WNS susceptibility of 13 species of western North American bats. Based on models derived from yeast species diversity, only one bat species, Myotis velifer, was predicted to be WNS resistant (i.e., may develop the disease, but with low mortality rates). We also screened yeasts found on western bats for P. destructans -antagonistic properties by spore germination and growth inhibition/competition assays and found the ability of yeasts to inhibit P. destructans in vitro to be strain specific. Similar to results of inhibition assays performed with yeasts isolated from bats in eastern North America, few yeasts isolated from bats in western North America inhibited P. destructans in vitro. Continued monitoring of western bat populations will serve to validate the accuracy of the mycobiome analysis in predicting WNS susceptibility, document population and susceptibility trends, and identify additional predictors to assess the vulnerability of naive bat populations to WNS. IMPORTANCE White-nose syndrome is one of the most devastating wildlife diseases ever documented. Some bat species are resistant to or tolerant of the disease, and we previously reported that certain traits of the skin mycobiome of bat species in eastern North America are strongly associated with resistance to WNS. Predicting which western bat species will be most susceptible to WNS would be of great value for establishing conservation priorities. Based on models derived from yeast species diversity, only one bat species was predicted to be WNS resistant. High susceptibility to WNS would pose a significant conservation threat to bats in western North America.

Pseudogymnoascus destructans is the causative agent of an emerging infectious disease that threatens populations of several North American bat species. The fungal disease was first observed in 2006 and has since caused the death of nearly six million bats. The disease, commonly known as white-nose syndrome, is characterized by a cutaneous infection with P. destructans causing erosions and ulcers in the skin of nose, ears and/or wings of bats. Previous studies based on sequences from eight loci have found that isolates of P. destructans from bats in the US all belong to one multilocus genotype. Using the same multilocus sequence typing method, we found that isolates from eastern and central Canada also had the same genotype as those from the US, consistent with the clonal expansion of P. destructans into Canada. However, our PCR fingerprinting revealed that among the 112 North American isolates we analyzed, three, all from Canada, showed minor genetic variation. Furthermore, we found significant variations among isolates in mycelial growth rate; the production of mycelial exudates; and pigment production and diffusion into agar media. These phenotypic differences were influenced by culture medium and incubation temperature, indicating significant variation in environmental condition--dependent phenotypic expression among isolates of the clonal P. destructans genotype in North America.