Resistance to Chytridiomycosis in European Plethodontid Salamanders of the Genus Speleomantes

Abstract

North America and the neotropics harbor nearly all species of plethodontid salamanders. In contrast, this family of caudate amphibians is represented in Europe and Asia by two genera, Speleomantes and Karsenia, which are confined to small geographic ranges. Compared to neotropical and North American plethodontids, mortality attributed to chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd) has not been reported for European plethodontids, despite the established presence of Bd in their geographic distribution. We determined the extent to which Bd is present in populations of all eight species of European Speleomantes and show that Bd was undetectable in 921 skin swabs. We then compared the susceptibility of one of these species, Speleomantes strinatii, to experimental infection with a highly virulent isolate of Bd (BdGPL), and compared this to the susceptible species Alytes muletensis. Whereas the inoculated A. muletensis developed increasing Bd-loads over a 4-week period, none of five exposed S. strinatii were colonized by Bd beyond 2 weeks post inoculation. Finally, we determined the extent to which skin secretions of Speleomantes species are capable of killing Bd. Skin secretions of seven Speleomantes species showed pronounced killing activity against Bd over 24 hours. In conclusion, the absence of Bd in Speleomantes combined with resistance to experimental chytridiomycosis and highly efficient skin defenses indicate that the genus Speleomantes is a taxon unlikely to decline due to Bd.

Recent Changes in Infectious Diseases in European Wildlife

“…European amphibians have heterogeneous responses to Bd exposure. Some species are susceptible to both infection and mortality attributable to chytridiomycosis, others seem less likely to suffer from either, and still others are refractory to infection (Pasmans et al 2013). At present, Bd is widespread across Europe, where the general pattern appears to be a coexistence steady state within amphibian communities (Balá et al 2014;Spitzen-van der Sluijs et al 2014).…”

Amphibian chytridiomycosis: a review with focus on fungus-host interactions

“…Unlike for anurans, information about the AMP arsenal in skin secretions of urodelans is scant. In several salamanders species, the antimicrobial action of skin secretions has been attributed to antimicrobial compounds, most probably including AMPs [ 90 , 91 ]. However, to date only a single antimicrobial peptide (the defensin CFBD) has been described from Cynops fudingensis (Fuding fire belly newt) [ 92 ], leaving a wealth of novel AMPs to be discovered.…”

“…To our knowledge, the antimicrobial action of CFBD against both Batrachochytrium species has not (yet) been evaluated. Although published data are virtually lacking, AMPs may be involved in the anti- B. dendrobatidis activity of salamander skin secretions [ 90 , 91 ] and potentially play a role in defense against B. salamandrivorans .…”

Emerging infectious disease threats to European herpetofauna

“…For more information on the environmental impact of hostpathogen interactions, which can be hugely deterministic in some cases, see Blaustein et al (2018) for an in-depth discussion. Experiments have also shown that some salamanders such as those in the genus Speleomantes also have some immunity to Bd (Pasmans et al, 2013). This combined effect of peptide defence and varying Bd strains show that at least for now, some species of European amphibians are protected against the potentially negative effects of Bd outbreaks (Fisher et al, 2009).…”