Scientific summary (cliquer ici pour la version française)

Climate change impacts plants and animals in various ways, including poleward shifts of their geographical distribution and changes in their phenology (i.e., date of occurrence of life-stages). Our objective is to determine how phenology can shape the spatial distribution of species in a changing climate (warming trend and increased variability). The applied objective is to take into account the changes in phenology to improve pest management methods. Our model species is the pine processionary moth, Thaumetopoea pityocampa, as its range expansion is climatically-driven. We will focus on species phenology on the field in task 1. Data will be collected on sites distributed in different French bioclimate regions and compared to data in the 1970s-1980s. We will also collect data on urbanization gradients to explore the effects of urban heat islands. We will determine microclimate conditions to estimate the temperature that individuals actually experience. Some individuals (from early to late phenologies) will be genotyped to determine whether they come from different populations, since in this case it may explain a larger variability in phenology. In addition, we will conduct experiments in controlled conditions in task 2 to determine the effects of temperature on the development of each biological stage and their thermal limits. With RNA-seq approaches, we will explore differential gene expression when individuals are exposed to heat stress. In task 3, we will develop biophysical models to describe microclimate temperatures. These models will be injected in a phenological model calibrated on data of task 2 and validated on data of task 1. We will then explore cascading effects of climate change based on changes in life-stage cycle and stage-specific constraints. This phenological model will be integrated into a spread model to clearly identify the role of climate change on species distribution via a change in phenology. Task 4 will be dedicated to the interaction with the society: an observer network will be created, a survey will be conducted on the needs of the society and a smartphone application will be developed so that anyone can report phenology events of pine processionary moth. These data from citizen science will allow to retrieve phenological information over a larger territory than our study sites. Lastly, a real-time map will be generated based on weather forecasts to alert about urtication risks related to the occurrence given life-stages (i.e., to protect human and animal health) and to set up biocontrol methods (i.e., to protect plant health) when it is the optimal time. The ambition of this proposal is to provide the very first study about the inter-relation between phenology and distribution in a changing climate. It is based on groundbreaking scientific approaches (e.g., phenological model based on performance curves, combination of phenological and spread models, real-time risk maps, trade-offs for gene expression after heat stress) and innovative field tools (e.g., network of automated connected traps and smartphone application). The applied ambition is also important with operational progresses (higher effectiveness of biocontrol) and it will raise public awareness about local effects of climate change.