DIVER’ANT

Project financing:

Total budget: 568 036 €

PSH budget: 204 379 €

Financier : Office Français de la Biodiversité

Digest:

Sap-sucking hemipterans such as aphids, mealybugs, or psyllids, include some of the most harmful pests in agriculture, due to the direct damage they cause to cultivated plants and the transmission of phytopathogenic viruses. They are the target of numerous insecticide treatments that are harmful to biodiversity and health. Diversification measures that favor regulation by natural enemies, such as predatory arthropods and parasitoids, are promising alternatives to agrochemicals. However, the frequent mutualistic relationship between these pests and ants strongly impedes the effectiveness of biological control. In exchange for honeydew, ants repel, disrupt or kill aphid natural enemies. Plant diversification measures in and around the plot could modify the range of resources available to ants and reduce mutualistic ant-aphid interaction, in favor of aphidophagous species. The impact of these measures on the frequentation of aphid colonies by ants and on aphid biological control needs to be assessed, and the conditions for their effectiveness determined. The Diver'Ant project (Ecophyto-II+, 2025-2027) aims to test this strategy in apple orchards against the rosy apple aphid. The spatial distribution of ant nests and the seasonal dynamics of food foraging (honeydew, nectar, preys) by the main aphid mutualist ant species, will be analyzed as a function of the level of plant diversification. The effectiveness of faba bean strips as a mean to divert ants away from aphids, by providing them with extrafloral nectar or alternative honeydew producing aphids will be assessed. In 2025, the study is replicated in four orchards in Angers, Avignon (France) and Lleida (Spain). Collected data will be used to analyse the impact of ant-aphid-natural enemies’ interaction on aphid dynamics and to determine the influence of habitat distribution in orchard on ant local abundance. Ultimately, these results will provide the basis to develop a decision-support tool for optimal setting of agroecological infrastructures in orchards.

PSH role:

The INRAE-PSH unit contributes to the Diver’Ant project through its expertise in analyzing biochemical and molecular profiles related to trophic interactions and in studying orchard arthropod communities, in order to better understand how ants interfere with biological control. In WP2, analytical chemistry approaches are developed to investigate ant feeding preferences (extrafloral nectaries, aphid honeydew, prey) depending on the floristic diversity surrounding ant colonies. In WP3, we study the seasonal dynamics of arthropod communities (ants, aphids, and natural enemies of aphids) in connection with the establishment of faba bean strips. We collect aphid predators and analyze their DNA to assess feeding changes in relation to the presence of ants and the development of the flora. Entomological monitoring and sampling are carried out both in both experimental (UE A2M) and commercial orchards from farms in the Lower Durance Valley (https://site-atelier-basse-valleedurance.fr/), in connection with the NextGenBioPest project.