Environmental DNA-based detection of Fascioloides magna and Galba truncatula: a non-invasive approach for monitoring invasive parasites

Invasive alien species, particularly microbial pathogens and parasites, pose significant threats to biodiversity, ecosystem stability, economies, food security, wildlife conservation, and public health. Their introduction can occur through human-mediated translocations or environmental factors such as weather patterns and extreme events. To predict, prevent, and manage emerging infectious diseases caused by invasive parasites, a multidisciplinary approach is essential. Invasion biology focuses on predicting potential invasive parasites before introduction, while wildlife veterinary medicine emphasizes early detection for effective prevention and management. Both approaches rely on continuous monitoring of invasive species and their hosts. The giant liver fluke (Fascioloides magna) has proven to be a highly successful invasive parasite, expanding its range through coevolution with native hosts, natural migration, human-facilitated transport, and environmental dispersal mechanisms like flooding and waterborne transmission. Effective monitoring strategies are needed to detect its presence and that of species involved in its life cycle as early as possible. In this study, a three-month environmental DNA (eDNA) screening was conducted in La Mandria Regional Park (Italy) to detect F. magna and its lymnaeid snail intermediate host, Galba truncatula, using water and soil samples. By integrating surface water dynamics for site selection, collecting multiple environmental matrices, and utilizing highly sensitive molecular methods (ddPCR), the study successfully identified both species without relying on prior biological distribution data, highlighting the effectiveness of eDNA-based surveillance for invasive parasites.