conference paper · ARPHA Conference Abstracts
Invasive species can introduce non-native parasites to indigenous wildlife, a process known as spill-over, or acquire local parasites through spill-back. Using an experimental tank system over a one-year period, captive aquaculture-bred Nile tilapia were co-housed with native Moroccan cichlid species to evaluate parasite transmission across species boundaries. Native flatworms maintained their populations without switching between native hosts. In contrast, five non-native parasite species successfully transmitted from the introduced Nile tilapia to native fishes, demonstrating that spill-over occurred far more frequently than spill-back. Although mean infection intensities remained low across all hosts, these host switches happened irrespective of the phylogenetic distance between the fish species. These findings confirm that aquaculture-associated fish introductions can introduce co-transported parasites capable of infecting native fauna, with intrinsic parasite traits appearing to drive host-switching success.
Anthropogenic movements of fish for aquaculture can unintentionally introduce non-native parasites into wild ecosystems. Demonstrating how readily flatworms jump from farmed Nile tilapia to indigenous fish helps conservationists and fishery managers understand transmission dynamics. The findings show that physical contact rather than genetic relatedness can enable parasite transmission, underscoring the biosecurity risks associated with introducing non-native species into natural waterways.
This early-stage experimental research provides foundational insights for aquaculture biosecurity, disease risk assessment, and fish health management protocols. Aquaculture operators, wildlife conservation bodies, and veterinary regulators could use these findings to design better parasite screening and containment strategies for translocated stock. However, because the study is limited to controlled tank trials exploring transmission mechanisms, practical biosecurity tools or commercial interventions remain at a basic research stage and require further development.
AI-generated from the published abstract. Always read the original work before citing.
A relatively poorly understood and insufficiently studied area of invasion biology is the risk that invasive species bring their parasites as hitchhikers, and potentially transmit them to native hosts (spill-over). Conversely, invaders may also be potential hosts for indigenous parasites (spill-back). They may thus alter an ecosystem’s natural host-parasite interactions in different ways. Determinants of whether and in which direction such transmissions happen are largely unknown, and characteristics allowing parasites to switch to a new host species are still poorly understood, especially in Africa, where empirical data are scarce. It is clear that, to predict and prevent pathogen transmission across species boundaries after anthropogenic translocations, studies on ecological and evolutionary aspects of infectious disease are important. The monopisthocotylan flatworms infecting cichlid fishes have been proposed as a metazoan model in such ecological and evolutionary parasitology. Indeed, their ubiquity, high species richness, simple (one host) lifecycle, and often relatively narrow host-specificity, render them ideal to study how parasites are influenced by their hosts’ biology. Furthermore, cichlid fishes are established model organisms across multiple biological disciplines, providing a robust phenotypic and genomic framework for this host–parasite system. In an exposure experiment, we studied potential links between the host offer and host-switching by parasites. We hypothesised that phylogenetic proximity of hosts plays a role in the success of host-switching under experimental conditions (as it probably also does over the course of the evolution of these host-parasite interactions). As an ecologically relevant system, we worked with the well-studied and species-depauperate monopisthocotylan fauna of the three cichlid fish species native to Morocco – Guinean tilapia ( Coptodon guineensis ), redbelly tilapia ( Coptodon zillii ), and blue tilapia ( Oreochromis aureus ), and one non-native species, Nile tilapia ( Oreochromis niloticus ), introduced into the country for aquaculture (and now established in the wild). In replicated tank experiments, aquaculture-bred non-native hosts ( O. niloticus ) were co-housed with pairs of wild-caught, potentially infected native species ( C. guineensis / C. zillii or C. guineensis / O. aureus ). This set-up allowed two-way host exposure to non-natural monogenean fauna, varying phylogenetic and ecological distances between fish hosts and parasites, respectively. Over a one-year timeframe, a proportion of fish specimens was regularly sacrificed and screened for monopisthocotylans. Native Cichlidogyrus cirratus and Cichlidogyrus cubitus maintained their captive populations throughout the experiment without host-switching between native hosts. Conversely, in the course of the experiment, five non-native monopisthocotylan species switched from Nile tilapia to native hosts: Cichlidogyrus sclerosus , Cichlidogyrus thurstonae , Cichlidogyrus tilapiae , Enterogyrus malmbergi , and Gyrodactylus yacatli . Over all host-parasite combinations, mean infection intensities were typically very low throughout the experiment. Spill-over events from Nile tilapia were far more frequent than spill-back from native hosts towards Nile tilapia. Since host-switches occurred irrespective of host phylogenetic distance, intrinsic characteristics of parasite species are suggested to determine host-switching events. Our results experimentally confirm that non-native hosts can act as sources of co-introduced parasites capable of infecting native hosts. Moreover, they highlight the risk of parasites crossing species boundaries under artificial conditions. In addition, we provide recommendations for future work to experimentally study host-switching in metazoan parasites.
This page summarises published work. The authoritative version sits with the publisher.
DOI: 10.3897/aca.9.e202257
Is something wrong with this record? Report it or request removal.
Discussion
Have you built on this work, tried to replicate it, or seen it applied in practice? Share what you know. Verified researchers and MARATTO™ domain experts can open a discussion, and any member can reply. Contributions are reviewed before they appear.
No discussion yet. Open the first thread.
New to MARATTO™? Create a free account.
