Microplastics and agrochemicals are common pollutants in terrestrial ecosystems. Their interaction during coexistence in soils may influence their fate and adverse effects on terrestrial organisms. The aim of this study was to investigate how the exposure to two types of microplastics; polyester fibres, and crumb rubber; induce changes in immune parameters of Porcellio scaber and if the co-exposure of microplastics affects the response induced by the organophosphate pesticide chlorpyrifos. A number of immune parameters, such as total haemocyte count, differential haemocyte count, and phenoloxidase-like activity were assessed. In addition, the acetylcholinesterase (AChE) activity in the haemolymph was evaluated as a measure of the bioavailability of chlorpyrifos. After three weeks of exposure, the most noticeable changes in the measured immune parameters and also a significantly reduced AChE activity were seen in chlorpyrifos-exposed animals. Both types of microplastic at environmentally relevant concentrations caused only slight changes in immune parameters which were not dependent on the type of microplastic, although the two types differed significantly in terms of the chemical complexity of the additives. Mixtures of chlorpyrifos and microplastics induced changes that differed from individual exposures. For example, alterations in some measured parameters suggested a reduced bioavailability of chlorpyrifos (AChE activity, haemocyte viability) caused by both types of microplastics exposure, but the increase of haemocyte count was promoted by the presence of fibres implying their joint action. In conclusion, this study suggests that immune processes in P. scaber are slightly changed upon exposure to both types of microplastics and microplastics can significantly modulate the effects of other co-exposed chemicals. Further research is needed on the short-term and long-term joint effects of microplastics and agrochemicals on the immunity of soil invertebrates.
Bibliographical noteFunding Information:
This work was supported by The Netherlands Organisation for Scientific Research (NWO); financing under the ERA-NET Waterworks2015 co-funded call in Water JPI [grant number ALWWW.2016.2 ]; and the Maj and Tor Nessling Foundation . The Slovenian Research Agency funded this research through the research programme Integrative zoology and speleobiology [grant number P1-0184 ], research project J1-2482 , the Slovenian Research Agency funding scheme for postgraduate research for Andraž Dolar, and the infrastructural Centre for Microscopy of biological samples, University of Ljubljana .
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- Crumb rubber particles from end-of-life tyre wear
- Immune response
- Microplastics mixture
- Organophosphorus pesticide chlorpyrifos
- Polyester fibres