[PhD defence] 10/04/2024 - Léo ROCHER: "Identification of vegetation parameters favouring beneficial arthropods and associated ecological functions in viticulture: a correlative and experimental approach" (IMBE)

Title of the thesis

"Identification of vegetation parameters favouring beneficial arthropods and associated ecological functions in viticulture: a correlative and experimental approach".

Date and place

Oral defense scheduled on wednesday 10 april 2024 at 2.30pm
Venue: Jean Henri Favre Campus, I.U.T., 337 Chemin des Meinajaries, 84140 Avignon
Room: Amphi IUT

Discipline

Biology

Laboratory

UMR 7263 IMBE - Mediterranean Institute of Biodiversity and Ecology EECAR

Framing

• Mr ARMIN BISCHOFF
• Mr OLIVIER BLIGHT

Composition of the jury

MR ARMIN BISCHOFF	Avignon University	Thesis supervisor
Claire Lavigne	UR PSH INRAE PACA	Examiner
Mr Adrien RUSCH	INRAE Nouvelle-Aquitaine	Rapporteur
Ms Anne-Violette LAVOIR	Côte d'Azur University	Rapporteur
Mr Joffrey MOIROUX	Avignon University	Examiner
Mr Olivier BLIGHT	Avignon University	Thesis co-director

Summary of the thesis

The decline in biodiversity in agro-ecosystems is largely attributed to the rise of modern agriculture. The main causes are the destruction of semi-natural structures, the extension of the size of agricultural plots and the intensive use of inputs. Arthropods play an important role in enhancing essential ecosystem services such as pest regulation and pollination. Vegetation is a key factor in encouraging their presence. Plants provide crucial food resources and habitats for arthropods. To encourage these organisms in agro-ecosystems and restore the associated ecological functions, practices such as the introduction of semi-natural structures are relevant. In permanent crops such as vineyards, such structures can be set up within the plots. In the Mediterranean region, vineyard inter-row management often involves eliminating uncultivated vegetation for reasons of water competition and to control plant species considered harmful. The aim of this thesis work is to gain a better understanding of how inter-row vegetation can promote the presence of beneficial arthropods and the predation function, while limiting the proliferation of harmful plant species in Mediterranean viticulture (Luberon, France). Three main research questions were addressed:

(1) Do the presence of grass cover and its plant composition influence the presence of ants, which are important predators in vineyards?

(2) Which vegetation functional groups are related to the abundance of predatory and pollinating arthropods and the predation function?

(3) Does diversified and local grass cover increase the presence of beneficial arthropods, improve the predation function and limit the establishment of problematic plant species? In the first chapter we studied the response of ants to grass cover in 23 vineyards. Ants play a crucial role in predation in Mediterranean vineyards (Luberon, France). We tested the effect of three vegetation management methods on the diversity and frequency of ants: inter-row grassing, partial grassing and no grassing. We showed that the partially grassed vineyards had a greater diversity of ants than the non-grassed vineyards. Grass cover and the presence of perennial plants positively influenced ant richness, suggesting the importance of taking these factors into account in vegetation management. In the second chapter, we examined which characteristics of spontaneous vegetation influence beneficial arthropods and predation function in 37 vineyards. We found that nectariferous flower cover and plant species richness favoured most groups of beneficial arthropods, as well as the predation function. These results underline the importance of floral resources and plant diversity in favouring the presence of the arthropods studied. Finally, the last chapter is devoted to a sowing experiment and its monitoring over two years. Three types of grassing were compared: high-diversity sowing, spontaneous vegetation and inter-rows without vegetation.

In line with the second chapter, our results highlight the positive effects of plant richness and flower cover on weed control, the abundance of beneficial arthropods and the predation function. All the results of this thesis work converge and highlight the importance of considering different vegetation parameters to favour beneficial arthropods in viticulture.

Keywords

Ecology, Botany, Agronomy, Entomology, Soil science, Conservation