Threats of the emerging pathogen Batrachochytrium salamandrivorans (Bsal) to Italian wild salamander populations
From Firenze University Press Journal: Acta Herpetologica
Lorenzo Dondero, Department of Earth, Environment and Life Sciences (DISTAV), University of Genova
Giorgia Allaria, Department of Earth, Environment and Life Sciences (DISTAV), University of Genova
Giacomo Rosa, Department of Earth, Environment and Life Sciences (DISTAV), University of Genova
Gentile Francesco Ficetola, Department of Environmental Science and Policy, University of Milan
Roberto Cogoni, Unione Speleologica Cagliaritana
Elena Grasselli, Department of Earth, Environment and Life Sciences (DISTAV), University of Genova
Sebastiano Salvidio, DISTAV
The chytrid fungi Batrachochytrium dendrobatidis(Bd) and Batrachochytrium salamandrivorans (Bsal) are amphibian pathogens that were introduced in Europe from East Asia, probably through the international trade (O’Hanlon et al., 2018; Laking et al., 2019). The con-tinuous spreading of these emerging pathogens is now threatening wild amphibian populations in different parts of Europe (Scheele et al., 2019; Bosch et al., 2021). In particular, the salamander killing fungus Bsal is a real threat to European salamanders, because many species are extremely susceptible to this infection and, therefore, highly vulnerable (Martel et al., 2014). The pathogenic effect of Bsal is caused by its zoosporangia that pene-trate the skin cells of adult salamanders, breaking innate immunological defences, and producing tissue erosions and deep ulcerations that may disrupt the host infected skin respiratory and rehydration functions (Martel et al., 2013; Grogan et al., 2020). In this way, Bsal infections are capable of causing severe illness or even death of the infected amphibian hosts (Martel et al., 2013, 2014). In fact, Bsal is constantly expanding from the Netherlands, where it was first detected and where it caused a popu-lation collapse in the local fire salamander Salamandra salamandra population (Martel et al., 2013). Currently, Bsal has been confirmed in about 80 localities surround-ing Bunderbos, in the Netherlands, where it was first detected (Martel et al., 2013), and also in Belgium and Germany (e.g., Spitzen-van der Sluijs, 2016; Lötters et al, 2020; Schmeller et al., 2020; Thein et al., 2020). Bsal has also been detected in 2018 in Catalonia (Northeastern Spain), where it has infected the marbled newt Triturus marmoratus and caused a local mass mortality event of this species (Martel et al., 2020), while its presence in North Central Spain has not been yet confirmed (Bosch et al., 2021). Therefore, to date, the presence of Bsal in Europe has been confirmed in the wild in four countries: The Netherlands, Belgium, Germany and Spain. The emergence and the diffusion of B. salamandrivoransthrough Europe, apparently facilitated by humans trans-ferring and introducing in the wild environment captive amphibians, is worrying and requests urgent prevention measures and monitoring actions to prevent further loss of amphibian diversity (Thomas et al., 2019). In particu-lar, the high salamander diversity of the southern Euro-pean peninsulas, such as Italy and Spain, appears at risk. Italy alone hosts 19 species of urodeles (Sindaco and Razzetti, 2021), many of which are endemic, such as the entire genus Salamandrina, the Italian newt Lissotriton italicus, the Sardinian brook newt Euproctus platycepha-lus, and seven species of cave salamanders belonging to the genus Speleomantes (Sindaco and Razzetti, 2021). However, to date, only two studies screened Bsal in Ital-ian salamanders (Grasselli et al., 2019, 2021). These stud-ies analysed by means of real-time PCR (qPCR) 136 skin swabs from 6 species of Italian wild salamanders and 53 from non-native individuals that were bred in pri-vate collections (Grasselli et al., 2019). The results from these studies were that none of the 189 Italian salaman-der swabs gave positive results. However, recent events raised concerns on the possibility of Bsal outbreaks in Italian populations. In the summer of 2021, a mass mor-tality of Speleomantes sarrabusensis was observed in Sar-dinia by the wildlife photographer Emanuele Biggi while, more recently (in spring 2022), a living fire salamander bearing skin lesions from Liguria was photographed by Michael Fahrbach and reported to the authors by Frank Pasmans from Ghent University. These observations were compatible with the suspected infection of Bsal on Italian amphibians but needed robust confirmation by molecular, and histological methods or by both. There-fore, the aim of this study was twofold: i) to expand the current knowledge about the presence of Bsal in wild salamander populations in Italy, adding the molecular data obtained from new skin samples collected from the two Bsal-suspected outbreaks and ii) to assess the susceptibility to Bsal of all Italian salamanders, on the basis of published experimental studies or, in the absence of experimental evidence, from their phylogenetic affinities. This information will be needed to better plan Bsal mitigation actions and also to guide strategic conservation and management efforts on the national territory of Italy.
DOI: https://doi.org/10.36253/a_h-13279
Read Full Text: https://oaj.fupress.net/index.php/ah/article/view/13279
