Plant-Insect Interactions in a Changing World

International audienceGlobal change is resetting the spatial and ecological equilibrium of complex co-evolutionary relationships between plants and their insect herbivores. We review the mechanisms at play in the responses of planteinsect interactions to global changes, including increased temperature and atmospheric CO2 concentrations, modification of land use and pollution. We distinguish between the direct effects of global changes on each partner from the indirect impacts on insects via the responses of plants. The indirect effects include a change in the nutritional quality of the plant tissues for herbivore insects, as well as a change in the microclimatic conditions at the leaf surface. Pollinators are involved in a close symbiotic relationship with their favourite plants, and any depression caused by climate stress can lead to pollination deficit. Pollinators are, indeed, quite sensitive to global changes. Furthermore, although species are connected by trophic links, all species respond differently to global changes. We highlight that more research is needed to elucidate the plant-mediated indirect effects of climate change on insects. Then, other human activities, such as land transformations and release of pollutants, are likely to modulate these links between climate and plant-insect relationships. We argue that predicting the net effect of global change on planteinsect relationships requires a comprehensive understanding of the mechanisms that modulate the interaction strength between the plants and the insects, rather than on focusing on each partner individually