Modern agriculture faces a dual challenge: reducing the use of pesticides while preserving biodiversity. By studying 18 apple orchards in Provence, INRAE and IMBE researchers have shown that spontaneous flora plays a key role in protecting crops by providing refuge and resources for pollinating insects and natural predators of pests.

In the Mediterranean apple orchards of the Basse Vallée de la Durance, INRAE researchers, in collaboration with the Institut Méditerranéen de Biodiversité et d'Écologie marine et continentale (IMBE), studied the interactions between spontaneous flora, pollinators and the main pests. They found that 5 to 10 % of flowers among this flora are enough to attract a significant diversity of beneficial insects. These include hoverflies and parasitoid wasps, two valuable allies in the fight against pests such as codling moth (Cydia pomonella) and the apple aphid (Dysaphis plantaginea), which are major threats to apple growing.

However, although spontaneous flora help to attract the natural enemies of insect pests, the results, published in the journal Agriculture, Ecosystems & Environment, do not yet guarantee a systematic reduction in infestations. Further research is needed to understand the mechanisms involved, and in particular the complex interactions between the various insects.

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The aim of the BEF-Cerrado project is to understand the mechanisms that encourage the establishment of native herbaceous plant communities in the Cerrado (Brazilian savannah, photos A and B). The experimental set-up involves creating 29 plant communities and testing the role of the species richness and functional richness of these communities in resisting invasions, being resilient in the face of endogenous disturbances (such as fires) and providing ecosystem processes (biomass production, soil erosion control, carbon storage or water infiltration). To do this, we chose 16 species of Poaceae and Cyperaceae (photo B) and created plant communities ranging from monocultures to communities of 4, 8 and 16 species. The experiment was set up on a degraded site in the Chapada dos Veadeiros National Park, initially converted to pasture and invaded by an exotic invasive species of African grass. Urochloa decumbens (photo C). As a first step, the top 30 cm of soil was stripped to eliminate the undesirable seed bank (photo D). Then 165 plots of 25m², divided into five blocks on the degraded site, were set up and the 29 communities planted (photos E and F). All the planting was carried out during the rainy season and completed on 10 February: 1,245 native seedlings were planted (photo G)!

For further information: https://anr.fr/Projet-ANR-23-CE02-0034