Plant diversification in agroecological vineyards: impact on predatory mite (Phytoseiidae) communities and potential natural regulations

Abstract: Viticulture is characterized by substantial use of pesticide inputs, unbalancing the
natural regulations in vineyards. Diversification of agroecosystems by integrating a greater
diversity of spontaneous or managed vegetation can provide refuges and alternative food
resources for beneficial organisms. Various meta-analyses support this hypothesis on a diversity of crops systems and scales, but gaps exist on the effect of this diversification on certain organisms, notably the Phytoseiidae predatory mites. Phytoseiidae are generalist predator reported as prevalent and efficient natural enemies in vineyards. They can feed on mite pests, small insects, pollen, nectar, and mycelium. This study aims at evaluating the effect of covercrops and agroforestery on Phytoseiidae communities in a Mediterranean agroecological vineyard with the resistant grape variety ‘Artaban’. Phytoseiidae and associated potential preys (Tydeidae, Eriophyidae and Thrips) were surveyed in 2022 on three different agroecosystems (control plot, cover-crop plot, cover-crop and agroforestery plot) on all vegetative compartments (vine, cover crops, trees). Main Phytoseiidae species on vine leaves were Typhlodromus exhilaratus, Euseius gallicus, Phytoseius finitimus, Kampimodromus aberrans and Typhlodromus recki. Some differences in Phytoseiidae density and diversity were observed between the three agroecosystems despite the proximity of the plots. Within the cover crops, a few plant species appear to be good reservoirs of Phytoseiidae, such as Erigeron sumatrensis, Helminthotheca echioides and Onobrychis viciifolia, hosting among others the main Phytoseiidae species found on vines. Concerning trees species, Ficus carica L. presents interesting results, hosting four of the five main Phytoseiidae species collected on vines. In 2023, plant phenotypic characters will be studied on plot to understand what makes a plant favourable to Phytoseiidae.