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# Wolbachia and diet modulation interact and affect the performance of an invasive fruit fly

Gwenaëlle Deconninck, Vincent Foray, Jordy Larges, Laureen Beaugeard,

Sylvain Pincebourde

► To cite this version:

Gwenaëlle Deconninck, Vincent Foray, Jordy Larges, Laureen Beaugeard, Sylvain Pincebourde. Wolbachia and diet modulation interact and affect the performance of an invasive fruit fly. 34e colloque Biotechnocentre, Oct 2022, Nouan-le-Fuzelier, France. . hal-03827196

HAL Id: hal-03827196

https://hal.science/hal-03827196

Submitted on 24 Oct 2022

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Distributed under a Creative Commons Attribution 4.0 International License
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## BACKGROUND

### Drosophila suzukii

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* Drosophilidae from Asia, **invasive** worldwide

* Highly **polyphagous** (cultivated and wild fruits)

* Lay eggs on **ripening fruits** unlike other *Drosophila*

* Present year-round

* Multiple generations per year (3 to 16)

### wSuz
(D. suzukii's Wolbachia strain)

* Variable prevalence (USA:17% / EU: 46%)

* Imperfect maternal transmission but **stably maintained** in populations

* **No consensus on wSuz effect:**

* No cytoplasmic incompatibility

* Effect on fecundity and viability

→ **Wsuz** may provide an advantage to *D. suzukii* when changing host, mitigating the physiological costs induced by its polyphagy

### Wolbachia

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* Intracellular **endosymbiont** of arthropods

* Infect ~50% of insect species

* Maternally transmitted

* Maintained by **manipulating reproduction** or **giving ecological advantage**

## Question: Could wSuz play a role in *Drosophila suzukii* performance after a diet shift?

## METHODS

### 4 lab populations of *D. suzukii*
with the same genetic background

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Maintained for > 10 generations

### Laying box preparation

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N = 25 ♀

25 females of each population were placed individually in laying boxes with 3 males. Each box contained either Corn or Grape medium for the females to lay on. Thus, the female had to lay eggs either on the medium they originated from or on a different medium, thereby simulating a diet shift.

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## RESULTS & DISCUSSION

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<table><thead><tr><th rowspan="2"></th><th rowspan="2">Stable medium</th><th colspan="2">Medium change</th></tr><tr><th>&rarr; &hearts; &hearts; &hearts;</th><th>&rarr; &hearts; &hearts;</th></tr></thead><tbody><tr><th>Fecundity</th><td>&hearts; &gt; &hearts;</td><td>&hearts;</td><td>&oplus;</td></tr><tr><th>Survival</th><td>ns</td><td>ns</td><td>ns</td></tr><tr><th>Offspring mass</th><td>ns</td><td>&hearts;</td><td>&oplus;</td></tr></tbody></table>

* Fecundity and mass modulated according to the new diet → females would favor a laying medium with suitable nutritional composition, otherwise lay fewer and poorer quality eggs

* The effect of diet shift on fecundity and offspring mass lessen after some generations to reach an intermediate value → niche adaptation

* **No effect on survival** → both media allow complete development

### MEDIUM

### EFFECT SUMMARY

### WOLBACHIA

wSuz might have an **energetic cost** for the female, reducing its egg production. However, it increased the offspring viability suggesting a **mutualistic role**. The mutualism might be linked to a **stressful situation** for the fly, such as the medium change.

### wSuz

<table><thead><tr><th></th><th>Stable medium</th><th>Medium change</th></tr></thead><tbody><tr><th>Fecundity</th><td>ns / &ominus;</td><td>&ominus;</td></tr><tr><th>Survival</th><td>ns</td><td>&oplus;</td></tr><tr><th>Offspring mass</th><td>ns / &ominus;</td><td>&oplus;</td></tr></tbody></table>

## PERSPECTIVES

### Broaden our knowledge on Wsuz role:

* How can it help *D. suzukii* in a natural context with multiple fruits?

* What is its physiological cost?

* Can it change if the abiotic environment (e.g., temperature, humidity) vary?

→ **Integrative approach is needed to answer**

* Slightly decrease in fecundity → Fitness cost

* Enhances larval survival → Better nutrient assimilation?

* Direct effect? E.g. amino acid or iron supplement

* Indirect effect? E.g. microbiome modulation

* Increases offspring mass only when medium changes → Relevant in a multitrophic context where *D. suzukii* females lay eggs on different fruits varying in nutritional composition

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### FOR FURTHER INFORMATION

Gwenaëlle Deconninck
deconninck@univ-tours.fr

### ACKNOWLEDGEMENTS

This work is part of the ANR project "What makes *Drosophila suzukii* such a successful invader? An integrative analysis of its thermal ecology." ANR-20-CE02-0011

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