“Determinants of taxonomic and functional diversity in arthropod communities in perennial crop landscapes”

Why insects are disappearing from our orchards... and how to remedy this

The alarming observation:

In agricultural environments, there is currently a sharp decline in the abundance and diversity of arthropods (insects, spiders, mites, etc.). This decline is worrying because these organisms perform essential ecological functions: pollination, natural pest control, recycling of organic matter, etc.

The suspected causes:

Two factors are often cited:

  • The simplification of agricultural landscapes: disappearance of hedges, homogenization of crops, reduction of semi-natural environments.
  • The use of pesticides, particularly insecticides, which directly or indirectly affect many species.

However, other agricultural practices (grass management, type of tillage, irrigation, etc.) can also influence these communities, but their effects are less well known and may vary depending on the landscape context.

What the thesis seeks to understand:

Based on a dataset collected over several years in different orchards, this research aims to study:

  • The diversity of species present (taxonomic diversity),
  • The ecological roles they fulfill (functional diversity),
  • How arthropod assemblages change from one orchard to another, in relation to local agricultural practices and the surrounding landscape.

It is therefore not just a question of measuring “how many” species are present, but how these communities are constructed, and what factors favor or limit certain species or ecological functions.

A better understanding of these mechanisms will enable us to:

  • Identify concrete levers for action at the plot level (e.g., vegetation cover management, reduction of inputs, etc.),
  • Guide the development of agricultural landscapes (e.g., maintenance of hedges, mosaic of environments, etc.).

The ultimate goal is to support agricultural practices that promote biodiversity while sustaining the sustainability of fruit production systems.

2025-2028