A dynamic model of the Xylella fastidiosa pathosystem as a tool to optimize management scenarios: An example using the almond tree

The almond tree (Prunus dulcis) is one of the most extensively grown species around the Mediterranean basin and has an important economic value for this region. Since 2016, the bacteria Xylella fastidiosa has spread and infected crops from the Balearic Islands and peninsular Spain. The main transmission vectors of X. fastidiosa in the Spanish Mediterranean are the xylem-feeding spittlebugs Philaenus spumarius and Neophilaenus campestris. Despite all the management strategies taken, the situation has become critical in certain areas. To support these efforts, this study develops a dynamic model considering the entire X. fastidiosa pathosystem (bacteria, host plants and insect vectors). The model is calibrated with field data from the Alicante province (Spain), available literature and some estimation of parameters. This tool makes it possible to compare and optimise management strategies. Sensitivity analysis showed that the most responsive variables of the model are Neophilaenus adult death rate, and larva growth and death rates. The model output replicates the decreasing productive tree population trend which happens in the crops affected by X. fastidiosa, even displaying the latency between when the plant is infected and when the symptoms appear. Summarising, the model is a great potential tool which can be used for the evaluation of contingency and preventive measures.