Parasites suffer too: Effects of host’s pollutant exposure on some life-history traits of acanthocephalan parasites
Résumé
Parasites are integral components of biodiversity, shaping host populations, food web dynamics, and ecosystem stability. However, they are influenced by environmental conditions and face growing threats. Despite growing evidence of global declines in parasite populations, the impacts of contaminants on their fitness in freshwater ecosystems remains poorly understood. In this study we investigated how environmental variability, host traits, and pollutant exposure affect the fitness and infection patterns of acanthocephalan parasites in chub (Squalius cephalus). Using a mesocosm approach, we assessed parasite infection intensity, size, and reproductive traits in relation to host size, body condition, site of capture, and seasonality, acknowledging that natural infections introduce variability. Moreover, we experimentally exposed chub to ubiquitous freshwater contaminants, including the pesticide imidacloprid, the pharmaceutical compounds paracetamol and diclofenac, and the herbicide S-metolachlor, at environmentally relevant concentrations. Our results indicate that host size was a key driver of parasite infection intensity. Parasite size increased over time but was independent of host condition and parasite density. While larger parasites produced more eggs, overall reproductive output declined in fish with better body condition and over time. Pollutant exposure yielded complex effects: chronic imidacloprid exposure (15 ng·g−1) reduced parasite size, while acute paracetamol exposure (16 μg·g−1) resulted in larger parasites but completely inhibited egg production. Other tested pollutants had no significant effects. These findings highlight the sensitivity of parasites to environmental stressors, the influence of host and environmental context, and the importance of accounting for natural variability and host-parasite interactions in ecotoxicological assessments of freshwater ecosystems.
Auteurs, date et publication :
Auteurs Léa Lorrain-Soligon , Simon Agostini , Alexandre Bauer , Beatriz Decencière , Côme Girard , Alexis Golven , Alexis Millot , Thierry Rigaud , Eliott Salles , Aurélie Goutte
Publication : International Journal for Parasitology
Date : 2025
Pages : 104761