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1. Reducing environmentally mediated transmission to moderate impacts of an emerging wildlife disease

   https://doi.org/10.1111/1365-2664.14371  

   Hoyt, Joseph R. ; Parise, Katy L. ; DePue, John E. ; Kaarakka, Heather M. ; Redell, Jennifer A. ; Scullon, William H. ; O'Reskie, Rich ; Foster, Jeffrey T. ; Kilpatrick, A. Marm ; Langwig, Kate E. ; et al ( March 2023 , Journal of Applied Ecology)

   Emerging infectious diseases have caused population declines and biodiversity loss. The ability of pathogens to survive in the environment, independent of their host, can exacerbate disease impacts and increase the likelihood of species extinction. Control of pathogens with environmental stages remains a significant challenge for conservation and effective management strategies are urgently needed.

   We examined the effectiveness of managing environmental exposure to reduce the impacts of an emerging infectious disease of bats, white‐nose syndrome (WNS). We used a chemical disinfectant, chlorine dioxide (ClO₂), to experimentally reducePseudogymnoascus destructans, the fungal pathogen causing WNS, in the environment. We combined laboratory experiments with 3 years of field trials at four abandoned mines to determine whether ClO₂could effectively removeP. destructansfrom the environment, reduce host infection and limit population impacts.

   ClO₂was effective at killingP. destructansin vitro across multiple concentrations. In field settings, higher concentrations of ClO₂treatment were needed to sufficiently reduce viableP. destructansconidia in the environment.

   The reduction in the environmental reservoir at treatment sites resulted in lower fungal loads on bats compared to untreated control populations. Survival following treatment was also higher in little brown bats (Myotis lucifugus), and trended higher for tricolored bats (Perimyotis subflavus).

   Synthesis and applications. Our results highlight that targeted management of sources for environmental transmission can be an effective control strategy for wildlife disease. We found that successfully reducing pathogen in the environment decreased disease severity and increased survival, but required higher treatment exposure than was effective in laboratory experiments, and the effects varied among species. More broadly, our findings have implications for other emerging wildlife diseases with free‐living pathogen stages by highlighting how the degree of environmental contamination can have cascading impacts on hosts, presenting an opportunity for intervention.

    

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

   https://doi.org/10.1002/ece3.5405  

   Kramer, Andrew M. ; Teitelbaum, Claire S. ; Griffin, Ashton ; Drake, John M. ( July 2019 , Ecology and Evolution)

   The introduced fungal pathogenPseudogymnoascus destructansis causing decline of several species of bats in North America, with some even at risk of extinction or extirpation. The severity of the epidemic of white‐nose syndrome caused byP. destructanshas prompted investigation of the transmission and virulence of infection at multiple scales, but linking these scales is necessary to quantify the mechanisms of transmission and assess population‐scale declines.

   We built a model connecting within‐hibernaculum disease dynamics of little brown bats to regional‐scale dispersal, reproduction, and disease spread, including multiple plausible mechanisms of transmission.

   We parameterized the model using the approach of plausible parameter sets, by comparing stochastic simulation results to statistical probes from empirical data on within‐hibernaculum prevalence and survival, as well as among‐hibernacula spread across a region.

   Our results are consistent with frequency‐dependent transmission between bats, support an important role of environmental transmission, and show very little effect of dispersal among colonies on metapopulation survival.

   The results help identify the influential parameters and largest sources of uncertainty. The model also offers a generalizable method to assess hypotheses about hibernaculum‐to‐hibernaculum transmission and to identify gaps in knowledge about key processes, and could be expanded to include additional mechanisms or bat species.

    

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3. Environmental transmission of Pseudogymnoascus destructans to hibernating little brown bats

   https://doi.org/10.1038/s41598-023-31515-w  

   Hicks, Alan C. ; Darling, Scott R. ; Flewelling, Joel E. ; von Linden, Ryan ; Meteyer, Carol U. ; Redell, David N. ; White, J. Paul ; Redell, Jennifer ; Smith, Ryan ; Blehert, David S. ; et al ( March 2023 , Scientific Reports)

   Pathogens with persistent environmental stages can have devastating effects on wildlife communities. White-nose syndrome (WNS), caused by the fungusPseudogymnoascus destructans,has caused widespread declines in bat populations of North America. In 2009, during the early stages of the WNS investigation and before molecular techniques had been developed to readily detectP. destructansin environmental samples, we initiated this study to assess whetherP. destructanscan persist in the hibernaculum environment in the absence of its conclusive bat host and cause infections in naive bats. We transferred little brown bats (Myotis lucifugus) from an unaffected winter colony in northwest Wisconsin to twoP. destructanscontaminated hibernacula in Vermont where native bats had been excluded.Infection withP. destructanswas apparent on some bats within 8 weeks following the introduction of unexposed bats to these environments, and mortality from WNS was confirmed by histopathology at both sites 14 weeks following introduction. These results indicate that environmental exposure toP. destructansis sufficient to cause the infection and mortality associated with WNS in naive bats, which increases the probability of winter colony extirpation and complicates conservation efforts.

    

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4. Body mass and hibernation microclimate may predict bat susceptibility to white‐nose syndrome

   https://doi.org/10.1002/ece3.7070  

   Haase, Catherine G. ; Fuller, Nathan W. ; Dzal, Yvonne A. ; Hranac, C. Reed ; Hayman, David T. S. ; Lausen, Cori L. ; Silas, Kirk A. ; Olson, Sarah H. ; Plowright, Raina K. ( December 2020 , Ecology and Evolution)

   In multihost 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 (WNS) 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 byP. 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 semipartial 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 WNS 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 WNS as the fungus continues to spread into western North America.

    

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5. Effects of wind energy generation and white-nose syndrome on the viability of the Indiana bat

   https://doi.org/10.7717/peerj.2830  

   Erickson, Richard A. ; Thogmartin, Wayne E. ; Diffendorfer, Jay E. ; Russell, Robin E. ; Szymanski, Jennifer A. ( December 2016 , PeerJ)

   Wind energy generation holds the potential to adversely affect wildlife populations. Species-wide effects are difficult to study and few, if any, studies examine effects of wind energy generation on any species across its entire range. One species that may be affected by wind energy generation is the endangered Indiana bat (Myotis sodalis), which is found in the eastern and midwestern United States. In addition to mortality from wind energy generation, the species also faces range-wide threats from the emerging infectious fungal disease, white-nose syndrome (WNS). White-nose syndrome, caused byPseudogymnoascus destructans, disturbs hibernating bats leading to high levels of mortality. We used a spatially explicit full-annual-cycle model to investigate how wind turbine mortality and WNS may singly and then together affect population dynamics of this species. In the simulation, wind turbine mortality impacted the metapopulation dynamics of the species by causing extirpation of some of the smaller winter colonies. In general, effects of wind turbines were localized and focused on specific spatial subpopulations. Conversely, WNS had a depressive effect on the species across its range. Wind turbine mortality interacted with WNS and together these stressors had a larger impact than would be expected from either alone, principally because these stressors together act to reduce species abundance across the spectrum of population sizes. Our findings illustrate the importance of not only prioritizing the protection of large winter colonies as is currently done, but also of protecting metapopulation dynamics and migratory connectivity.

    

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