# Vectors of Xylella fastidiosa show pronounced habitat preferences in Corsican agricultural landscapes

Xavier Mesmin, Marguerite Chartois, Jean-Pierre Rossi, Jean-Yves Rasplus, Astrid Cruaud

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Xavier Mesmin, Marguerite Chartois, Jean-Pierre Rossi, Jean-Yves Rasplus, Astrid Cruaud. Vectors of Xylella fastidiosa show pronounced habitat preferences in Corsican agricultural landscapes. 3rd European Conference on Xylella fastidiosa and XF-ACTORS final meeting, Apr 2021, Online Event, France., 10.5281/zenodo.4680115. hal-03845146

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Submitted on 16 Nov 2022

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Distributed under a Creative Commons Attribution 4.0 International License
# Vectors of Xylella fastidiosa show pronounced habitat preferences in Corsican agricultural landscapes

Mesmin X.; Chartois M.; Rossi J.-P.; Rasplus J.-Y; Cruaud A.

CBGP, INRAE, CIRAD, IRD, Montpellier SupAgro, Univ Montpellier, Montpellier, France
# INTRODUCTION – MATERIALS & METHODS

* Most insect vectors of *Xylella fastidiosa* (*Xf*) are generalists but tend to **aggregate on preferred host plants**¹,².

* Such preferences may have consequences on the **relative importance of different insect species in the transmission of Xf to crops**.

* We assessed the **habitat preferences of spittlebugs** on and in the vicinity of **clementine** and **olive** groves in Corsica.

## M&M

* **16 organically managed sites** were selected within a **climatically homogeneous region of Corsica** (Fig. 1).

* Spittlebugs were monitored inside and around the groves **three times a year** (April, June and October) during **two years** (2019, 2020).

* Spittlebugs were monitored **by sight** in the spring and by **sweep netting** in the summer and fall.

* **Four habitats** were monitored in each site (see next slide).

<figure><img src="image_2.png" /><figcaption>B</figcaption></figure>

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

Fig. 1 Sampling sites on clementine and olive groves in the eastern plain of Corsica.
TYPE OF HABITATS INCLUDED IN THE STUDY

* On each site, the four habitats were chosen in **close vicinity** (< 500 m), so that **spittlebugs** were **theoretically able to shift between habitats** in a short time.

* Insect densities reflect **habitat preferences** at the local scale.

<figure><img src="image_4.png" /><figcaption>*Cistus monspeliensis border*
(expected preferred host of *Philaenus spumarius*3,4)</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>*Dittrichia viscosa cover*
(expected alternative host of *P. spumarius*, pers. obs.)</figcaption></figure>

Crop
foliage

Grove ground
vegetation

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

<figure><img src="image_7.png" /></figure>
# INTERACTION NETWORKS SHOW A PREDOMINANT *P. SPUMARIUS-C. MONSPELIENSIS* INTERACTION

<caption>Fig. 2 Seasonal interaction networks.</caption>

Nc = *Neophilaenus campestris*, Aa = *Aphrophora alni*, Lc = *Lepyronia coleoptrata*, Ps = *Philaenus spumarius*
GV = ground vegetation, CF = crop foliage, Dv = *Dittrichia viscosa*, Cm = *Cistus monspeliensis*

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

* Host preferences were **particularly strong** in April

* No spittlebug nymph was **found on the foliage** of either olive or clementine trees.

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

* Few spittlebugs were collected in June and **P. spumarius** was not **predominant**.

* Only *A. alni* and *L. coleoptrata* were found on the crop foliage.

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

* The **most complex interaction network** was obtained in October.

* The interaction **P. spumarius-C. monspeliensis** constituted half of this network.

* All species but *L. coleoptrata* were found on the crop foliage.
# CONSEQUENCES FOR THE MANAGEMENT OF XF

## CONCLUSION

* *Cistus monspeliensis* and *D. viscosa* were respectively confirmed as preferred and alternative host of *P. spumarius* in Corsica. This result contrasts with published works on olive groves in Spain⁵ and Italy⁶.

* Host preferences may vary under similar geographic and climatic contexts.

* No summer migration of *P. spumarius* to crop foliage as reported in Italy⁷ was recorded in Corsica. We found that the four spittlebug species have similar abundances on the crop foliage.

* Provided that the four species have similar transmission efficiencies, **they may contribute similarly to Xf propagation in Corsican olive and clementine groves.**

## APPLIED PERSPECTIVES

* Managing *P. spumarius* by means of soil tillage in spring would probably be **less efficient in the Corsican context than in Italy.**

* The management of *C. monspeliensis* borders in the close vicinity of Corsican groves may decrease density of *P. spumarius* and thus, the threat posed to the adjacent tree crop.

## References:

1 R. Karban, M. Huntzinger, *Ecology.* **99**, 2614-2616 (2018)

2 A. Latini et al., *Environ Sci Pollut Res.* **26**, 6503-6516 (2019)

3 A. Cruaud et al., *Sci. Rep.* **8** (2018)

4 J. Albre et al., *Bull. Entomol. Res.* **111**, 246-256 (2021)

5 M. Morente et al., *Insects.* **9**, 175 (2018)

6 N. Bodino et al., *Insects.* **11**, 130 (2020)

7 D. Cornara et al., *J Pest Sci.* **90**, 521-530 (2017)