Exploring future changes in synchrony between grapevine (Vitis vinifera) and its major insect pest, Lobesia botrana

The European grapevine moth (Lobesia botrana) is one of the major pests of the grapevine (Vitis vinifera) in Europe. The phenology of both the insect pest and the plant has already changed over the last decades in response to rising temperatures, with a tendency towards an earlier development. The impact of a warming climate, among other factors, could alter matches in phenology between two trophic levels, being either beneficial or detrimental to V. vinifera. As a consequence, when considering a European latitudinal transect, the changes toward synchrony or a mismatch are not fully understood. In this study, we applied the results of sequential models to simulate the phenological development of V. vinifera from dormancy to physiological maturity of Chardonnay or a similar grape variety. Likewise, we simulated the phenology of L. botrana with a process-based voltinism model. Both models were calibrated and validated in previous studies. The present study aims at simulating the future evolution of both trophic levels under changing climatic conditions at four representative European locations by using quasi-transient climate scenarios up to the year 2100 that consider the RCP4.5 and RCP8.5 greenhouse-gas forcing pathways. Although some physiological adaptations could alter these results, simulations of synchrony under climate change are crucial for the adaptation of grape cultivation and varieties. This modelling work seeks to improve our understanding of the probable shifts in the timing and spatial distribution of the plant-insect interactions in a warmer climate and how this may impact their synchrony. A risk index of damage has been implemented for the different sites and greenhouse gas forcing trajectories. Results suggest an increasing damage risk for V. vinifera close to the timing of harvests in northern Europe. They also point to increasing mortality rates of the fourth generation of L. botrana in southern Europe, where temperatures will increasingly reach the upper thermal limit for insect development.