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1. 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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2. Mobility and infectiousness in the spatial spread of an emerging fungal pathogen

   https://doi.org/10.1111/1365-2656.13439  

   Langwig, Kate E. ; White, J. Paul ; Parise, Katy L. ; Kaarakka, Heather M. ; Redell, Jennifer A. ; DePue, John E. ; Scullon, William H. ; Foster, Jeffrey T. ; Kilpatrick, A. Marm ; Hoyt, Joseph R. ( February 2021 , Journal of Animal Ecology)

   Emerging infectious diseases can have devastating effects on host communities, causing population collapse and species extinctions. The timing of novel pathogen arrival into naïve species communities can have consequential effects that shape the trajectory of epidemics through populations. Pathogen introductions are often presumed to occur when hosts are highly mobile. However, spread patterns can be influenced by a multitude of other factors including host body condition and infectiousness.

   White‐nose syndrome (WNS) is a seasonal emerging infectious disease of bats, which is caused by the fungal pathogenPseudogymnoascus destructans. Within‐site transmission ofP. destructansprimarily occurs over winter; however, the influence of bat mobility and infectiousness on the seasonal timing of pathogen spread to new populations is unknown. We combined data on host population dynamics and pathogen transmission from 22 bat communities to investigate the timing of pathogen arrival and the consequences of varying pathogen arrival times on disease impacts.

   We found that midwinter arrival of the fungus predominated spread patterns, suggesting that bats were most likely to spreadP.destructanswhen they are highly infectious, but have reduced mobility. In communities whereP. destructanswas detected in early winter, one species suffered higher fungal burdens and experienced more severe declines than at sites where the pathogen was detected later in the winter, suggesting that the timing of pathogen introduction had consequential effects for some bat communities. We also found evidence of source–sink population dynamics over winter, suggesting some movement among sites occurs during hibernation, even though bats at northern latitudes were thought to be fairly immobile during this period. Winter emergence behaviour symptomatic of white‐nose syndrome may further exacerbate these winter bat movements to uninfected areas.

   Our results suggest that low infectiousness during host migration may have reduced the rate of expansion of this deadly pathogen, and that elevated infectiousness during winter plays a key role in seasonal transmission. Furthermore, our results highlight the importance of both accurate estimation of the timing of pathogen spread and the consequences of varying arrival times to prevent and mitigate the effects of infectious diseases.

    

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3. 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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4. 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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5. Field trial of a probiotic bacteria to protect bats from white-nose syndrome

   https://doi.org/10.1038/s41598-019-45453-z  

   Hoyt, Joseph R. ; Langwig, Kate E. ; White, J. Paul ; Kaarakka, Heather M. ; Redell, Jennifer A. ; Parise, Katy L. ; Frick, Winifred F. ; Foster, Jeffrey T. ; Kilpatrick, A. Marm ( June 2019 , Scientific Reports)

   Tools for reducing wildlife disease impacts are needed to conserve biodiversity. White-nose syndrome (WNS), caused by the fungusPseudogymnoascus destructans, has caused widespread declines in North American bat populations and threatens several species with extinction. Few tools exist for managers to reduce WNS impacts. We tested the efficacy of a probiotic bacterium,Pseudomonas fluorescens, to reduce impacts of WNS in two simultaneous experiments with caged and free-flyingMyotis lucifugusbats at a mine in Wisconsin, USA. In the cage experiment there was no difference in survival between control andP.fluorescens-treated bats. However, body mass, not infection intensity, predicted mortality, suggesting that within-cage disturbance influenced the cage experiment. In the free-flying experiment, where bats were able to avoid conspecific disturbance, infection intensity predicted the date of emergence from the mine. In this experiment treatment withP.fluorescensincreased apparent overwinter survival five-fold compared to the control group (from 8.4% to 46.2%) by delaying emergence of bats from the site by approximately 32 days. These results suggest that treatment of bats withP.fluorescensmay substantially reduce WNS mortality, and, if used in combination with other interventions, could stop population declines.

    

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