Résumé
Espelette pepper farmers are currently facing devastating and recurrent viral epidemics due to a recent emergence of Cucumber mosaic virus (CMV). A collaboration between the “Syndicat du Piment d’Espelette AOP” (which federates Espelette pepper farmers) and the Virology team of the Plant Pathology unit of INRAE (Avignon) has emerged to investigate these epidemics and propose control strategies. To identify relevant and promising strategies, it is first necessary to acquire data on the virus epidemiology in the local context and understand what drives CMV epidemics in the Espelette area. In particular, it is currently unclear how CMV re-emerges every year on pepper crops despite the absence of pepper during winter. It is also intriguing to observe such severe epidemics in this area, where the high level of landscape fragmentation and plant biodiversity is generally predicted to mitigate disease spread.In this study, we explored the possibility of year-to-year seed transmission from infected fruits, of the presence of alternative hosts (serving as viral reservoir and thus inoculum sources) around pepper fields as well as the role of aphid vectors (mediating plant-to-plant transmissions). For this, we first performed large-scale surveys to collect samples (seeds, plants, aphids) in the Espelette area and monitor CMV incidence in different elements of the agricultural landscape (pepper crops, surrounding crops, wild plants). Second, we ran greenhouse experiments in controlled conditions to assess the efficiency of seed- and aphid-mediated transmission.This work enables the evaluation of the respective roles of the different CMV dissemination pathways and helps decipher the key drivers of CMV epidemics in the Espelette area. These results will guide future research efforts and help prioritize management options for further investigation.