Predators as a possible strategy for controlling a Xylella epidemic?

Abstract

In Southern Italy, since 2013, there has been an ongoing Olive Quick Decline Syndrome (OQDS) outbreak, due to the bacterium Xylella fastidiosa, which has caused a dramatic impact from both socio-economic and environmental points of view. Current agronomic practices are mainly based on uprooting the sick olive trees and their surrounding ones, with later installment of olive cultivars more resistant to the bacterium infection. Unfortunately, both of these practices are having an undesirable impact on the environment and on the economy. Here, a spatially structured mathematical model has been proposed to include a predator Zelus renardii as a possible biocontrol agent of the Xylella epidemic. The fact that Z. renardii has been reported to be a generalist predator implies that its introduction is not an efficient control strategy to eradicate a Xylella epidemic. Instead, a specialist predator, whenever identified, would lead to the eventual eradication of a Xylella epidemic. In either cases it has been confirmed that a significant reduction of the weed biomass can lead to the eradication of the vector population, hence of a Xylella epidemic, independently of the presence of predators.