The Role of Predators in Controlling the Spread of an Epidemic in Agriculture: The Case of Xylella fastidiosa

In this chapter, the role of a predator is analyzed as a possible biocontrol agent of epidemics in agriculture. As a concrete application, the case of Zelus renardii has been considered as a predator of Philaenus spumarius, for a possible control of a Xylella epidemic, which has been the subject of the previous chapter. By taking into account previous investigations, we show that the choice of the functional response to predation is crucial. Possible choices adopted in literature are the Holling type II predator (specialist) and the Holling type III predator (generalist). The analysis presented here shows that a H. II predator, whenever identified, would indeed lead to the eventual eradication of a Xylella epidemic. Unfortunately, Z. renardii has been reported to be a generalist predator, which implies an Holling type III functional response to predation; we show that it is not an efficient control strategy to eradicate a Xylella epidemic. All of that has been illustrated by a set of computational experiments, within a variety of different possible parameter scenarios.