Host, Pathogen, and Environmental Characteristics Predict White-Nose Syndrome Mortality in Captive Little Brown Myotis (Myotis lucifugus)

Abstract

An estimated 5.7 million or more bats died in North America between 2006 and 2012 due to infection with the fungus Pseudogymnoascus destructans (Pd) that causes white-nose syndrome (WNS) during hibernation. The behavioral and physiological changes associated with hibernation leave bats vulnerable to WNS, but the persistence of bats within the contaminated regions of North America suggests that survival might vary predictably among individuals or in relation to environmental conditions. To investigate variables influencing WNS mortality, we conducted a captive study of 147 little brown myotis (Myotis lucifugus) inoculated with 0, 500, 5 000, 50 000, or 500 000 Pd conidia and hibernated for five months at either 4 or 10°C. We found that female bats were significantly more likely to survive hibernation, as were bats hibernated at 4°C, and bats with greater body condition at the start of hibernation. Although all bats inoculated with Pd exhibited shorter torpor bouts compared to controls, a characteristic of WNS, only bats inoculated with 500 conidia had significantly lower survival odds compared to controls. These data show that host and environmental characteristics are significant predictors of WNS mortality, and that exposure to up to 500 conidia is sufficient to cause a fatal infection. These results also illustrate a need to quantify dynamics of Pd exposure in free-ranging bats, as dynamics of WNS produced in captive studies inoculating bats with several hundred thousand conidia may differ from those in the wild.

Antibodies to Pseudogymnoascus destructans are not sufficient for protection against white‐nose syndrome

“…2014). Bats were either cutaneously inoculated with Pd ( n  = 118) or sham inoculated ( n  = 29) with PBS, and hibernated for 5 months in captivity.…”

“…In addition to collecting blood, we scored the wings for damage considered to be a secondary symptom of WNS (Reichard and Kunz 2009) and swabbed the wings and muzzles to later determine the number of Pd cells present (Johnson et al. 2014). …”

“…We swabbed the muzzles and wings of bats to confirm the presence of Pd by qPCR (Johnson et al. 2014). Bats were aroused for ≥1 h before being euthanized using isoflurane followed by decapitation.…”

The other white‐nose syndrome transcriptome: Tolerant and susceptible hosts respond differently to the pathogen Pseudogymnoascus destructans

“…In tolerant species, tolerance has been primarily attributed to the varying environmental conditions in which different species hibernate (Hayman et al., 2016; Johnson et al., 2014), and to “coevolution with the pathogen” (Leopardi et al., 2015; Wibbelt et al., 2010). Persistent selective pressure by P. destructans (i.e., coevolution) can explain WNS tolerance in contemporary populations, but the molecular responses of species that have evolved tolerance of P. destructans have not been characterized.…”

Spatial pattern of genetic diversity and selection in the MHC class II DRB of three Neotropical bat species

“…A strong correlation was also shown between host and parasite species richness, their life history and ecological traits [26–28]. Moreover, anthropogenic alterations of habitats induce changes in host–pathogen–environment interactions and are consequently linked to the emergence of infectious zoonotic diseases [29–31]. Therefore, considering the role of the environment is critical for the assessment of MHC gene variability.…”