Résumé
Sphaerothecum destruens, an emerging aquatic pathogen, presents significant threats to biodiversity conservation and aquaculture sustainability due to its broad host range and close association with the invasive Pseudorasbora parva. This study reports the first detection of S. destruens in freshwater fish from the Po River basin (Italy), encompassing both native and non-native species. Molecular analysis revealed S. destruens infection in four positive Barbus barbus specimens and identified four additional potential positive samples, including Barbus barbus, Pseudorasbora parva, and Padogobius bonelli. Prevalence rates varied across sampling sites, with infection rates of 3.45 % in Moncalieri, 19.23 % in Murazzi, and 5.26 % in San Mauro. Notably, species-specific prevalence was highest in Pseudorasbora parva (50 %) and Padogobius bonelli (33.33 %) at Murazzi. Prevalence in Barbus barbus was site-dependent, with rates of 4.17 %, 42.86 %, and 8.00 % recorded at Moncalieri, Murazzi, and San Mauro, respectively. The findings reveal site-specific variability in S. destruens prevalences, influenced by environmental conditions and the presence of invasive species like P. parva, which act as reservoirs and vectors for pathogen dissemination. The results underscore the importance of molecular diagnostic tools for detecting asymptomatic infections, which are often overlooked using conventional approaches. To mitigate the ecological and economic impacts of S. destruens, targeted management strategies are essential, focusing on limiting the spread of S. destruens and implementing proactive surveillance. These measures are critical for protecting aquatic biodiversity in the Po River basin and other vulnerable ecosystems.
•First detection of Sphaerothecum destruens in Po River basin freshwater fish.•Highest prevalence in Pseudorasbora parva and Padogobius bonelli.•Molecular tools crucial for detecting asymptomatic S. destruens infections.