Hibernation temperature-dependentPseudogymnoascus destructansinfection intensity in Palearctic bats

Abstract

White-nose syndrome (WNS) is a fungal disease caused by Pseudogymnoascus destructans that is devastating to Nearctic bat populations but tolerated by Palearctic bats. Temperature is a factor known to be important for fungal growth and bat choice of hibernation. Here we investigated the effect of temperature on the pathogenic fungal growth in the wild across the Palearctic. We modelled body surface temperature of bats with respect to fungal infection intensity and disease severity and were able to relate this to the mean annual surface temperature at the site. Bats that hibernated at lower temperatures had less fungal growth and fewer skin lesions on their wings. Contrary to expectation derived from laboratory P. destructans culture experiments, natural infection intensity peaked between 5 and 6°C and decreased at warmer hibernating temperature. We made predictive maps based on bat species distributions, temperature and infection intensity and disease severity data to determine not only where P. destructans will be found but also where the infection will be invasive to bats across the Palearctic. Together these data highlight the mechanistic model of the interplay between environmental and biological factors, which determine progression in a wildlife disease.

Transcriptional host–pathogen responses of Pseudogymnoascus destructans and three species of bats with white-nose syndrome

“…it develops only mild clinical signs). Samples were therefore collected after the bats had reached late hibernation to allow fungal load and number of fluorescing WNS lesions to peak before sampling [17,Supporting Information]. Full details of animal collection, care, permits and accession numbers for these samples are provided in the Supporting Information.…”

“…Palearctic bat species that have co-evolved with P. destructans develop only mild clinical signs [16][17][18], while susceptibility to WNS varies among Nearctic species that were first exposed since P. destructans was introduced to eastern North America [7,19,20]. Understanding the genetic and behavioral basis for interspecific variation in susceptibility to WNS has been a critical research focus since the disease was described [7,14,17,[21][22][23][24][25][26][27]. However, our understanding of the molecular response of hibernating bats to WNS is largely limited to studies of the little brown bat [Myotis lucifugus ; 8,28,29].…”

“…Characterizing interspecific variation in the molecular responses to WNS during hibernation could identify drivers of susceptibility, tolerance, and resistance to fungal infections [8,24,28] and inform studies of other fungal pathogens. It could also improve predictions of the effects of WNS as P. destructans continues to spread [17,25,31,32]. Specifically, the accuracy of such predictions could be improved by understanding whether the molecular response of hibernating bats to P. destructans reflects evolutionary history (i.e., is more similar among related species) or reflects a species' susceptibility, tolerance, or resistance to the pathogen [24,33].…”

Multiscale model of regional population decline in little brown bats due to white‐nose syndrome

“…We also conducted an experiment examining the impact of potential variation in fungal growth rates between hibernacula. Cave microclimate is known to influence Pd growth (Forsythe et al, 2018;Martínková et al, 2018;Verant et al, 2012) and survival of infected bats (Langwig et al, 2012). Thus, we constructed a scenario in which the rate of disease progression to moderately infected (γ 1 ) varies among hibernacula.…”

Bat population recoveries give insight into clustering strategies during hibernation

“…Bats hibernating in tree hollows, under bark, or in shallow rock crevices face high risk that the ambient temperature at the hibernaculum will fluctuate daily over about 10°C and could drop below zero [11,13]. While deep underground hibernacula present more stable microclimates, cave-dwelling bats are able to choose different roosts, resulting in exposure to temperatures differing by more than 7°C [14]. Movement within underground hibernacula enables the bats to change their roost microclimate.…”