Batrachochytrium salamandrivorans (Bsal) is a recently discovered fungal pathogen that has caused declines of wild Fire Salamander (Salamandra salamandra) populations across Europe. Risk models based on environmental suitability suggest that Bsal poses high risk to North American amphibian biodiversity, especially in the southeastern and northwestern USA. Our goal was to estimate the susceptibility of 29 North American amphibian species to Bsal infection and chytridiomycosis. Experimental animals were exposed to one of four Bsal zoospore doses (103-6), and their condition monitored for at least six weeks. We swabbed animals every six days to estimate Bsal infection intensity.
Results/Conclusions
Of the species tested, approximately 75% became infected and 30% developed Bsal chytridiomycosis. Generally dose-dependent infection prevalence and mortality were observed. Susceptible species that developed clinical Bsal chytridiomycosis and mortality included: Chiropterotriton sp., Aquiloeurycea cephalica, Ensatina eschscholtzii, Aneidis aeneus, Eurycea wilderae, Pseudotriton ruber, Notophthalmus viridescens, N. meridionalis, N. perstriatus and Taricha granulosa. Tolerant species that maintained low intensity Bsal infections over several successive swabs included seven caudates: Ambystoma opacum, A. mexicanum, Cryptobranchus alleganiensis, Desmognathus aeneus, D. ocoee, E. lucifuga and Plethodon metcalfi. Five anuran species were also tolerant of Bsal infection, including Anaxyrus americanus, Hyla chrysoscelis, Lithobates chirichahuensis, Scaphiopus holbrookii and Osteopilus septentrionalis. Resistant species that did not maintain Bsal infections after exposure included: A. latarele, D. monticola, Hemidactylium scutatum, Necturus maculsosis, L. sylvaticus, L. catesbeianus, and P. shermani x teyahalee. Our results suggest that most North American amphibian communities will be composed of a combination of amplification, tolerant and resistant host species, which could facilitate the emergence, spread and maintenance of Bsal in the western hemisphere. We recommend that natural resource and wildlife health agencies deem the introduction of Bsal into the USA, Canada and Mexico as a serious conservation threat, proactively establish regulations to reduce the likelihood of introduction, and support research and planning activities to evaluate disease intervention strategies that could thwart emergence of Bsal upon introduction.