# Unraveling Effects of a Pesticide Mixture on Earthworm Life-Cycle

Lisa Gollot, Rémy Beaudouin, Juliette Fabure, Raphaël Royauté

► To cite this version:

Lisa Gollot, Rémy Beaudouin, Juliette Fabure, Raphaël Royauté. Unraveling Effects of a Pesticide Mixture on Earthworm Life-Cycle. DEB2025 9th International Symposium, Jun 2025, Heraklion, Greece. 2025. [hal-05189720](https://hal.inrae.fr/hal-05189720v1)

HAL Id: hal-05189720

https://hal.inrae.fr/hal-05189720v1

Submitted on 28 Jul 2025

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<figure><img src="image_1.png" /></figure>

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# Unraveling Effects of a Pesticide Mixture on Earthworm Life-Cycle

Lisa Gollot (1,2), Rémy Beaudouin(2) Juliette FABURÉ (1), Raphaël ROYAUTÉ (1)

Contact e-mail : lisa.gollot@inrae.fr

(1) Université Paris-Saclay, INRAE, AgroParisTech, UMR ECOSYS, 91120 Palaiseau, France

(2) Experimental Toxicology and Modeling Unit, INERIS, 65550 Verneuil en Halatte, France

# Toxic Cocktails in our Soils: When Pesticides join Forces against Earthworms

## 1 Introduction

Due to agricultural practices, earthworms are typically exposed to mixtures of pesticide residues rather than individual substances.

**Study objective**

Assess and quantify the interaction of a binary pesticide mixture on earthworm life-cycle.

Mixture: Imidacloprid (IMD, insecticide) & Epoxiconazole (EPX, fungicide)

<figure><img src="image_2.png" /><figcaption>Photo 1 A. caliginosa</figcaption></figure>

### 3 possible scenarios

<figure><img src="image_3.png" /></figure>

<figure><img src="image_4.png" /></figure>

<figure><img src="image_5.png" /></figure>

## 2 Method

### Growth & Reproduction tests

<figure><img src="image_6.png" /></figure>

$T_{\text{exp}} = 18^{\circ}\text{C}$

<figure><img src="image_7.png" /></figure>

### How to study binary mixtures ?

### 1 Dose-response curves

<figure><img src="image_8.png" /></figure>

### 2 Ray design to study the mixture

<figure><img src="image_9.png" /></figure>

### 3 Interaction estimation → Jonker simple interaction model

### Modelling mixture effects with a DEB-TKTD model

Where does
synergy emerge
in a DEB-TKTD
framework?

<figure><img src="image_10.png" /></figure>

1. TK-based
interaction
OR

2. TD/DEB-based
interaction

### Acknowledgments

The authors thank Laura Frattaroli, Julien Rouyer, Cheikh Ahmed Tidiane Sarr, Maia Collombel, and Valentine Lebars for their valuable support during the experiments, and Ghislaine Delarue for conducting the chemical analyses.

### Funding

* ANR EEWORM

* PhD grant from the GS Biosphera

## 3 Results

### Toxicokinetics of the single substances

based on OECD TG n°317

<figure><img src="image_11.png" /></figure>

<figure><img src="image_12.png" /></figure>

<figure><img src="image_13.png" /></figure>

<figure><img src="image_14.png" /></figure>

→ Very different
behaviors

### Dose-response curves

### Reproduction

<figure><img src="image_15.png" /></figure>

### Growth

<figure><img src="image_16.png" /></figure>

→ The investigation of a mixture effect could only be done on reproduction

### Dose-response surface

<figure><img src="image_17.png" /></figure>

<figure><img src="image_18.png" /></figure>

Interaction parameter : $a = -2^*$

→ SYNERGY

F-test : p-value = 0.005

against reference model (CA)

*Simple interaction model (Jonker, 2005)

## 4 Discussion & Conclusion

The mixture of **IMD** & **EPX** is **more toxic** than the
single substances

Origine of the interaction ?

<figure><img src="image_19.png" /></figure>

<figure><img src="image_20.png" /></figure>

<figure><img src="image_21.png" /></figure>

→ To be investigated with bioconcentration measurements

### Further goal

Modeling the earthworm life-cycle under a mixture
exposure with a DEB-TKTD model

### References

Baas, J., Jager, T., & Kooijman, B. (2010). A review of DEB theory in assessing toxic effects of mixtures. *Science of The Total Environment*

Cedergreen, N., Kamper, A., & Streibig, J. C. (2006). Is prochloraz a potent synergist across aquatic species? A study on bacteria, daphnia, algae and higher plants. *Aquatic Toxicology*

Jonker, M. J., Svendsen, C., Bedaux, J. J. M., Bongers, M., & Kammenga, J. E. (2005). Significance testing of synergistic/antagonistic, dose level-dependent, or dose ratio-dependent effects in mixture dose-response analysis. *Environmental Toxicology and Chemistry*