Investigating how bat ectoparasites influence the skin microbiome diversity and composition in Washington State bats
White-Nose Syndrome (WNS), caused by the psychrophilic pathogenic fungus Pseudogymnoascus destructans (Pd), has killed millions of bats in the eastern United States since its initial introduction in 2006 and recent expansion into the western U.S. Understanding factors that contribute to the spread of Pd and risk of infection is crucial for management of WNS. Bat ectoparasites, including bat mites and bat flies, are omnipresent in bat populations, yet the relationship between these ectoparasites and bat health is still unknown. We examined the relationship between bat ectoparasites and the skin microbiome in relation to WNS infection risk in Washington State bats. We hypothesized that bats with ectoparasites would have a decreased skin microbiome diversity thus increasing their susceptibility to Pd infection. We collaborated with Washington Department of Fish and Wildlife during Spring 2021, sampling 147 bats representing five different species across 10 bat roosts in Washington State. We found that certain bat species were more likely to be infested with ectoparasites than others, especially Eptesicus fuscus (p = 0.0429) and Myotis volans (p = 0.0094). Using next-gen sequencing techniques, we found that ectoparasite infestation did not decrease the skin microbiome diversity of Washington bats (p = 0.965), although bat species (p = 0.006) and roost location (p = 0.001) significantly influenced the skin microbiome diversity. Using culturing methods, we identified 20 species of culturable bacteria from bat skin with four isolates belonging to genera known to possess antifungal properties. These isolates could be used to develop probiotic therapies for local colonies to prevent and treat WNS in the future.
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