Bioaccumulation, trophic transfer and exuvial elimination of polystyrene nanoplastics in a terrestrial predator-prey system.

Despite the ubiquitous spread of nanoplastics, their trophic transfer and biological impacts in terrestrial ecosystems remain poorly understood. Here, europium-labelled 100 nm polystyrene nanoparticles (Eu-PS-NPs) were used as a tracer to investigate their accumulation, trophic transfer, and sublethal effects along a terrestrial predator-prey interaction involving larvae of carabid beetle Carabus lefebvrei and the snail Cantareus aspersus. Inductively coupled plasma mass spectrometry demonstrated significant accumulation in beetle larvae fed contaminated snails (0.01 and 0.1% w/w). Trophic transfer factors remained below 1, indicating no biomagnification. Eu-PS-NPs were mainly retained within the larval digestive tract (0.013 ± 0.004 and 0.072 ± 0.006 µg g-1 in the 0.01% and 0.10% Eu-PS-NP group, respectively), whereas lower concentrations were detected in larval gut-free tissues (0.0033 ± 0.0005 and 0.011 ± 0.004 µg g-1, respectively). They were also detected in exuviae (0.049 ± 0.019 and 0.171 ± 0.022 µg g-1, respectively), suggesting ecdysis as a potential overlooked elimination pathway. Although survival was unaffected, significant sublethal effects, including reduced moulting rate and altered phenoloxidase activity, indicated developmental and immune modulation. These findings demonstrate that dietary nanoplastic exposure induces measurable physiological stress in terrestrial predators despite the absence of biomagnification. This study advances understanding of nanoplastic dynamics in terrestrial food webs and highlights the role of ecdysis in regulating particle burdens.