MODELLING THE IMPACT OF CLIMATE CHANGE ON SUSTAINABLE MANAGEMENT OF THE CODLING MOTH (CYDIA POMONELLA) AS KEY PEST IN APPLE

Climate change in temperate regions will lead to higher and more extreme temperature distributions; however, its impact on pests and their control strategies is rarely investigated in detail. One reason is the problem of downscaling climate predictions to the temporal and spatial scale of pest life cycles. In the present study, we have closed that gap by impact modelling on hourly scale and downscaling on spatial scale, by adapting a stochastic weather generator (WG) for pest modelling. Thereby, the codling moth, Cydia pomonella, serves as a relevant model species for a key pest with multiple generations per year that, already under the present climate, requires intensive efforts to control. Stochastic weather generation, followed by a re-sampling approach, provided hourly synthetic weather data for 10 meteorological sites in Switzerland under future climate conditions (2045-2074). Synthetic weather was analysed by a phenology model implemented in the forecasting system SOPRA. The results showed significant shifts to earlier dates in codling moth phenological events in Swiss apple orchards, increased magnitude of the 2nd generation, less overlap between stages, and a bigger risk for an additional 3rd generation. Shifts in phenology and magnitude of later generations require adaptations of plant protection regimes to maintain their sustainability, as we illustrate in the present paper, specifically for the strategies in codling moth control. In general, however, methodologies may easily be adapted in further pest and disease combinations and cropping systems.