A physiologically-based model predicting phenology and abundance of Philaenus spumarius, the main vector of Xylella fastidiosa in Europe.

The meadow spittlebug Philaenus spumarius (Linnaeus) is a common and widespread xylem-sap feeder in Europe. The species has been recently discovered as the main vector of the gram-negative bacterium Xylella fastidiosa (Wells) known as the causal agent of the olive dieback in Apulia (southern Italy). Since then, the vector became one of the major concerns posed to European agriculture. Only the adult stage of P. spumarius is able to acquire the bacterium X. fastidiosa through feeding on the xylem sap of infected host plants. Once the adult acquired the bacterium, it is persistently infected and can immediately transmit the pathogen to healthy plants, as latency in the vector is not required. Therefore, the capacity to predict the population phenology and abundance of P. spumarius is a key element for understanding the epidemiology of X. fastidiosa as well as for the development of targeting control interventions for rational management strategies against both the vector and the bacterium. Here, we present a physiologically-based mechanistic model predicting the spatio-temporal variation of phenology and population abundance of P. spumarius. The model describes the life-history strategies of the different biological stages by means of stage-specific development, mortality and fertility rate functions. The rate functions describe the physiological responses of the species to local environmental forcing variables (e.g. air temperature) and resources (e.g., host plant availability). The rate function's parameters have been estimated through data obtained from laboratory and field experiments. The model has been calibrated and validated using independent population dynamics datasets from Apulia and Liguria regions (Italy). Model outputs can be used for assessing the risks linked to P. spumarius population dynamics and X. fastidiosa epidemiology. Model simulations can also support the design and implementation of monitoring and control activities for managing the X. fastidiosa-plant-vector pathosystem.