The recently discovered fungal pathogen Batrachochytrium salamandrivorans (Bsal) has caused population declines of wild fire salamanders (Salamandra salamandra) in Europe. Recent experimental challenges suggest that Bsal is highly pathogenic to species in the family Salamandridae. In particular, the Eastern Newt (Notophthalmus viridescens) is highly susceptible to Bsal. There are two other species of Notophthalmus native to North America (the Black-spotted Newt, N. perstriatus, and the Striped Newt, N. meridionalis), both of which are of high conservation concern. It is unclear whether these species are also susceptible to Bsal, and understanding the susceptibility of these species to Bsal is essential to estimating risk of Bsal emergence and planning conservation strategies for these species. Thus, our goal was to robustly estimate the susceptibility of species in the genus Notophthalmus to Bsal. We conducted experimental challenges with the fungus by exposing individuals of each species to Bsal in a water bath at one of four zoospore concentrations (5x103-6) or to a water only control for 24h, then monitored their condition for at least 6wks.
Results/Conclusions
Clinical signs of disease varied by dose, the most common of which were skin sloughing and ulcerative lesions, and in some cases death. N. perstriatus, N. meridionalis, and eft-stage N. viridescens were highly susceptible to Bsal and experienced dose dependent mortality with 100% mortality observed in the highest zoospore dose. The overall susceptibility of adult N. viridescens to Bsal was moderate (61% in the highest zoospore dose), and varied by population with newts originating from Michigan having the highest incidence of mortality (100% mortality in the highest zoospore dose). Additionally, subclinical Bsal infections were observed in all three species lasting the duration of the experiment (at least six weeks), suggesting these species might function as biological reservoirs and facilitate maintenance of Bsal in North America. Our results indicted that Notophthalmus could play a significant role in the epidemiology of Bsal if it emerges in North America.