Entre pressions chimiques et climatiques : réponses développementales, reproductives, et physiologiques de l’Eudémis de la vigne à l’usage de la bouillie bordelaise dans un contexte de réchauffement climatique en Bourgogne

Within agroecosystems, insects are exposed to multiple pressures, both chemical and climatic. Although pesticides are designed to target specific organisms, many of these substances are non-selective and cause collateral damage to a wide range of species. Copper-based fungicides, widely used in viticulture to control fungal diseases, can also affect non-target fauna including the European grapevine moth Lobesia botrana. In the context of climate warming, this southern pest is expected to expand its distribution toward higher latitudes. Rising temperatures could alter the effects of Bordeaux mixture on L. botrana, either by increasing its tolerance to the fungicide or by exacerbating its toxic effects. This thesis therefore aimed to assess the effects of Bordeaux mixture on L. botrana under simulated current (2002–2021) and future (2081–2100) climate conditions in Burgundy. The results showed that the fungicide negatively affected the pest’s development and reproduction. The future climate scenario mitigated the fungicide’s impact on larval development but enhanced its effects on adult reproduction. Physiological mechanisms underlying these responses were also identified, highlighting an energetic trade-off between defense mechanisms and growth or reproductive processes throughout the pest’s life cycle. This work highlights the importance of considering the interactions between chemical and climatic stressors when assessing pest-related risks. It provides key insights for anticipating the future of viticulture facing rapid environmental change and the multiple threats arising from it.