# DNA barcoding and metabarcoding as complementary approaches to investigate the impact of predation by an invasive species on earthworm communities

Shanèze Noël, Mathis Ventura, Yoan Fourcade, Andréa Barraux, Agnès Gigon, Virginie Roy, Lise Dupont

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Shanèze Noël, Mathis Ventura, Yoan Fourcade, Andréa Barraux, Agnès Gigon, et al.. DNA barcoding and metabarcoding as complementary approaches to investigate the impact of predation by an invasive species on earthworm communities. ID-ADN 2024 - L'ADN pour identifier et suivre la biodiversité: avancées, méthodes et données pour la recherche, les collections et les politiques publiques, Nov 2024, PARIS, France. hal-04952684

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Submitted on 17 Feb 2025

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# DNA barcoding and metabarcoding as complementary approaches to investigate the impact of predation by an invasive species on earthworm communities

Shanèze NOËL, Mathis VENTURA, Yoan FOURCADE, Andréa BARRAUX, Agnès GIGON, Virginie ROY, Lise DUPONT

Université Paris-Est Créteil, Sorbonne Université, CNRS, INRAE, IRD, iEES Paris, 94010 Créteil Cedex, France

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## Introduction

Invasive terrestrial flatworms, through their **predatory behavior**, can be responsible for major **ecological disturbances** to prey population and soil fauna community structure.

Earthworm communities in Europe may be **severely disrupted** by the introduction of the exotic predator *Obama nungara*, a terrestrial flatworm native from South America. This flatworm has invaded 72 departments of metropolitan France and is mostly found in **anthropogenic environments** [1]. Experimental data showed that it feeds on **earthworms**, terrestrial gastropods and other land planarians [2].

To investigate the **impact** of an invasive species through time we can either monitor the community of its prey through field sampling and **barcoding** OR **high-throughput sequencing** to detect prey DNA in the predator **gut content**. In this study, we used both methods and explored their efficiency when **implemented together**, especially when used on predators with cryptic behavior predating on cryptic species.

## Material & Methods

Sampling in 10 invaded gardens in Autumn 2021 and Spring 2022

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## Results

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## Conclusions

26 earthworm species and lineages were detected in the digestive contents, confirming that *O. nungara* presents a large dietary diversity. 5 additional species were detected through barcoding on the field and 3 other species were detected only in gut contents, confirming the need of complementary approaches to investigate the impact of predation by this invasive species.

Results show that epigeic earthworms are massively represented in gut contents but are not as abundant in the field community. Furthermore, *A. caliginosa* (endogeic) and *L. friendi* (anecic) are the most eaten as well as the most abundant.

The complementary use of DNA barcoding and metabarcoding approaches therefore makes it possible to explore questions such as the availability of earthworm prey for the flatworm depending on the microhabitat occupied (e.g. galleries within soil, litter) and preferential predation choice.

### What's next?

Two more years of sampling will be analyzed, and results will be compared through time to assess *O. nungara*'s diet and impact on earthworm communities! The same work will be performed on gastropods to know the impact on the whole community of *O. nungara*'s prey!

[1] Justine, J. L., Winsor, L., Gey, D., Gros, P., & Thévenot, J. (2020). *Obama chez moi! The invasion of metropolitan France by the land planarian *Obama nungara* (Platyhelminthes, Geoplanidae)*. *PeerJ*, *8*, e8385.

[2] Boll, P. K., & Leal-Zanchet, A. M. (2016). Preference for different prey allows the coexistence of several land planarians in areas of the Atlantic Forest. *Zoology*, *119*(3), 162-168.

[3] Bouché, M. B. (1977). Stratégies lombriciennes. *Ecological Bulletins*, *25*, 122-132.