Modelling the impact of climate change on the interaction between grapevine and its pests and pathogens: European grapevine moth and powdery mildew

Climate change may impact patterns of plant diseases and arthropod development in more complex ways than expected. In fact, whereas both crops and crop pathogens and pests are affected by climatic variables, they might be influenced by different combinations of driving factors, and they might respond to their change at different rates. In order to separate these effects, we need to improve our understanding of the host-pest/pathogen system, and consider their interaction. The aim of this study was to refine current assessments of climate change impacts on pest and disease pressure on grapevines by considering pest/pathogen–host interactions. This research (i) combined detailed phenological models of grapevine with phenological models of one of its key insect pests (European grapevine moth) and one of its key pathogens (powdery mildew), (ii) applied the models to climate change scenarios for a selected study area in the eastern Italian Alps, and (iii) considered potential changes in their interactions. These simulations suggest that in the warmer, more profitable viticultural areas of the study region increasing temperature might have a detrimental impact on crop yield due to increased asynchrony between the larvae-resistant growth stages of grapevine and larvae of the European grapevine moth. On the other hand, the increase in pest pressure due to the increased number of generations might not be as severe as expected on the basis of the pest model only, due to the advance in harvest dates limiting damages from late-season generations. Simulations for powdery mildew highlighted a decrease in simulated disease severity, especially in years with a later onset of the disease symptoms and in the climate scenario with higher temperature increases.