Modelling the spread of Xylella fastidiosa in Puglia, Italy

Xylella fastidiosa is a xylem-limited Gram-negative bacterium and the recognized agent of a number of severe diseases, among which Pierce’s dis ease of the grapevine, leaf scorch of almond, oleander and coffee, citrus variegated chlo rosis, and other disorders of perennial crops and landscape plants. Once restricted to the Americas, the disease was discovered near Lecce, Italy in 2013, and since the initial outbrea k, it has spread and affected 8000 hectares of olive trees in the Puglia region of Southern Italy. X. fastidiosa bacterium is transmitted by various species of sap -sucking hopper insects. Infection occurs after a vector has fed o n an infected plant and then subsequently feeds on a healthy plant. X. fastidiosa has a very broad range of known host plants in the EU, including many grown for agricultural production, a nd hence the disease could have a large impact on food production. Importantly, the sap-s ucking hopper insects found in the EU that could potentially carry the disease are likely to h ave different feeding habits and patterns, thus making spread predictions difficult. These facts suggest that the potential spread of X. fastidiosa is of great concern. In this talk we will present a model for the spread of X. fastidiosa throughout the Puglia region. By first considering a simplification of an establi shed multi spatial scale model, we parameterise the infection dynamics using field dat a. These dynamics are then coupled with a dispersal kernel, and the current distribution and intensity of host plant species throughout the region, to realistically represent the potential sp read. We present our case scenario results as well as the impacts of roguing (infected plant remo val), which have significant effects on the spread.