Body mass and hibernation microclimate may predict bat susceptibility to white-nose syndrome

In multi-host disease systems, differences in mortality between species
may reflect variation in host physiology, morphology, and behavior. In
systems where the pathogen can persist in the environment, microclimate
conditions, and the adaptation of the host to these conditions, may also
impact mortality. White-nose syndrome is an emerging disease of
hibernating bats caused by an environmentally persistent fungus,
Pseudogymnoascus destructans. We assessed the effects of body mass, torpid
metabolic rate, evaporative water loss, and hibernaculum temperature and
water vapor deficit on predicted overwinter survival of bats infected by
P. destructans. We used a hibernation energetics model in an
individual-based model framework to predict the probability of survival of
nine bat species at eight sampling sites across North America. The model
predicts time until fat exhaustion as a function of species-specific host
characteristics, hibernaculum microclimate, and fungal growth. We fit a
linear model to determine relationships with each variable and predicted
survival and semi-partial correlation coefficients to determine the major
drivers in variation in bat survival. We found host body mass and
hibernaculum water vapor deficit explained over half of the variation in
survival with white-nose syndrome across species. As previous work on the
interplay between host and pathogen physiology and the environment has
focused on species with narrow microclimate preferences, our view on this
relationship is limited. Our results highlight some key predictors of
interspecific survival among western bat species and provide a framework
to assess impacts of white-nose syndrome as the fungus continues to spread
into western North America.