Recent introduction of a chytrid fungus endangers Western Palearctic salamanders

Abstract

Emerging infectious diseases are reducing biodiversity on a global scale. Recently, the emergence of the chytrid fungus Batrachochytrium salamandrivorans resulted in rapid declines in populations of European fire salamanders. Here, we screened more than 5000 amphibians from across four continents and combined experimental assessment of pathogenicity with phylogenetic methods to estimate the threat that this infection poses to amphibian diversity. Results show that B. salamandrivorans is restricted to, but highly pathogenic for, salamanders and newts (Urodela). The pathogen likely originated and remained in coexistence with a clade of salamander hosts for millions of years in Asia. As a result of globalization and lack of biosecurity, it has recently been introduced into naïve European amphibian populations, where it is currently causing biodiversity loss.

Mitigating amphibian chytridiomycoses in nature

“…Similarly, we have gained important insights into the European emergence of another chytrid fungus, Batrachochytrium salamandrivorans (Bsal) [3]. Unfortunately, the development of field interventions for disease management has lagged far behind and managing amphibian health in nature remains a largely unexplored topic [4][5][6].…”

“…via trade regulations, such as the recent establishment of restrictions on caudate amphibian trade in the USA in response to the emergence of B. salamandrivorans, https://federalregister.gov/a/2016-00452) are probably the most effective disease mitigation measure available [9,10]. The international movement of amphibians plays a continuing role in establishing and extending the distribution of amphibian-associated chytrids and other pathogens, but the control of chytridiomycosis and other purely wildlife diseases is largely overlooked in commercial trade [3,[11][12][13]. The World Organisation for Animal Health (OIE) is the international body that can regulate this, but even though its remit includes wildlife conservation it has a poor track record in doing so.…”

In peril from a perfect pathogen

“…Although previous experiments 6 suggested that the host-range of Bsal was limited to species of newts and salamanders, the authors found that a species of frog, Alytes obstetricans, could be infected by the fungus and transmit the disease to salamanders. Infection of alpine newts (Ichthyosaura alpestris) that share the forests with the salamanders alongside A. obstetricans then showed that the newts could develop chronic Bsal infections.…”

Rhinosporidiosis in African reed frogs Hyperolius spp. caused by a new species of Rhinosporidium

“…Recently, a second Batrachochytrium species (B. salamandrivorans) of probable Asian origin has been identified causing catastrophic die offs in salamanders in the Netherlands (Martel et al 2013. Unlike Bd, the new pathogen seems to be restricted to urodele hosts (Martel et al 2014). However, Batrachochytrium species are not the only pathogens which infect amphibians.…”