Environmental control reduces white-nose syndrome infection in hibernating bats

Infectious diseases caused by invasive, environmentally persistent fungal pathogens have increasingly endangered global biodiversity, yet disease management remains a major conservation challenge. A prominent example is white-nose syndrome (WNS), a disease caused by the invasive fungal pathogen Pseudogymnoascus destructans (Pd) that has devastated populations of multiple North American bat species, but for which few effective management tools exist. Here, we propose that strategies to delay environmental transmission of Pd during early winter could limit WNS disease effects across winter, benefitting bats. We used a small captive experiment and a multi-year field trial on wild, free-ranging bats to assess an environmental control strategy to manage Pd within its environmental reservoir in Pennsylvania, USA, where the pathogen has become endemic. The strategy centers on the application of Polyethylene Glycol 8000 (PEG) to roost substrates in summer, prior to bat hibernation, as a means to disrupt environmental transmission to bats in early winter. In the captive experiment, environmental transmission of Pd to immunologically naive little brown myotis (Myotis lucifugus) occurred from roost substrates inoculated with Pd, but the application of PEG to these substrates effectively blocked this transmission. In the field trial, Pd load and infection extent both declined substantially in free-ranging M. lucifugus after treatment relative to controls, with declines exceeding effects of inter-site and inter-annual variation. Pathogen prevalence and load also declined substantially after PEG treatment in big brown bats (Eptesicus fuscus). No negative effects of PEG treatment were observed in body condition or colony counts of bats or in the microbial community. Together, these results are consistent with effective environmental control of Pd and reduced WNS disease effects in bats within contaminated hibernacula. The results also highlight the potential of carefully designed environmental control strategies for managing environmentally persistent pathogens.