Evaluation of epoxiconazole bioavailability in soil to the earthworm Aporrectodea icterica

Sylvie Nelieu (1) , Ghislaine Delarue (1) , Elodie Ollivier (1, 2) , Pierre Awad (1) , Christian Mougin (1, 2) , Céline Pelosi (1)

1 ECOSYS - Ecologie fonctionnelle et écotoxicologie des agroécosystèmes
2 Plateforme BIOCHEM-ENV

In soil, the determination of total concentration using an exhaustive extraction method is not relevant to evaluate the exposure of an organism to a chemical, because of sorption processes. However, little attention has been paid to the bioavailability of organic contaminants to earthworms, and to their effect on sensitive earthworm species found in cultivated fields, such as Aporrectodea icterica [1]. As ecosystem engineers, earthworms influence soil structure and chemistry and are thus key-organisms for the health of terrestrial ecosystems. However, they can be threatened by contaminants such as the fungicide epoxiconazole, which is persistent in soil and presents a chronic toxicity even towards a resistant earthworm species (Eisenia fetida) at a concentration close to the recommended dose. This study aimed to propose a mild extraction method to evaluate the bioavailability of the fungicide epoxiconazole to the earthworm Aporrectodea icterica [2]. Experiments were conducted in soils presenting various textures and organic carbon contents, spiked with formulated epoxiconazole 7 to 56 days prior to their extraction at one-fold to ten-fold the recommended dose. In parallel, the epoxiconazole concentration was determined in exposed earthworms. All the analysis were performed by UHPLCMS/ MS. The fungicide’s effects were evaluated by measuring weight gain, enzymatic activities and total protein contents. The proposed method to evaluate bioavailability was based on the pesticide entrapment in the cavity of hydroxypropyl-?-cyclodextrin, thus fulfilling the criteria of the ISO 17402 norm [3]. Furthermore, this mild method was demonstrated to be sensitive to soil sorption capacities and to ageing. The mild extraction method was then applied to explore the relationship between total and bioavailable concentrations in soil and in A. icterica, over 7 or 28 days exposure time. This demonstrated the proportionality between epoxiconazole concentration in earthworm and available in soil (up to 96%, with regression coefficient R2 0.98). Sublethal effects on earthworm remained not significant. References 1. C. Pelosi, S. Joimel, D. Makowski, 2013. Chemosphere 90, 895-900 2. S. Nélieu, G. Delarue, E. Ollivier, P. Awad, F. Fraillon, C. Pelosi, Environ. Sci. Pollut. Res. In Press DOI 10.1007/s11356-015-5270-4 3. ISO 17402, 2008. Soil quality - Guidance for the selection and application of methods for the assessment of bioavailability of contaminants in soil and soil materials

Domaines: Sciences du Vivant [q-bio]

Sylvie Nelieu, Ghislaine Delarue, Elodie Ollivier, Pierre Awad, Christian Mougin, et al.. Evaluation of epoxiconazole bioavailability in soil to the earthworm Aporrectodea icterica. SETAC Europe 26th Annual Meeting, May 2016, Nantes, France. , 2016. ⟨hal-01532561⟩