Authors Steven M. White, James M. Bullock, Danny A. P. Hooftman and Daniel S. Chapman based at the Centre for Ecology & Hydrology, have created a model, based on Xylella fastidiosa's spread in Apulia, Italy.
The model can qualitatively and quantitatively predict how the deadly bacterial pathogen may spread as well as offer guidance on how buffer zones should be arranged to protect uninfected olive trees.
The research, published in the journal Biological Invasions, highlights how Xylella fastidiosa is influenced by insects including spittlebugs and the rate to which these vectors contribute to the potential spread of the disease across Europe and beyond.
They said: "The rapid invasion of X. fastidiosa causing Olive Quick Decline Syndrome (OQDS) in Italy is causing substantial damage to olive production and the local economy, and is extremely worrying for neighbouring olive-producing regions in Italy and in other Mediterranean regions. Predicting its spread is important, since this will help guide control strategies and assess risk, and existing statistical distribution models (Bosso et al 2016) only predict the potential spatial extent of the disease, not the rate and patterns of spread or impacts of spatial control approaches. Here, we have developed a simple model based on previous work (Chapman et al. 2015) which we have compared to the known spatial and temporal dynamics of X. fastidiosa and shown that the model qualitatively reproduces the pattern and speed of spread of X. fastidiosa in the Apulian region.
"We model control zones currently employed in Apulia, showing that increasing buffer widths decrease infection risk beyond the control zone, but this may not halt the spread completely due to stochastic long-distance jumps caused by vector dispersal. Therefore, management practices should aim to reduce vector long-distance dispersal. We find optimal control scenarios that minimise control effort while reducing X. fastidiosa spread maximally - suggesting that increasing buffer zone widths should be favoured over surveillance efforts as control budgets increase. Our model highlights the importance of non-olive hosts which increase the spread rate of the disease and may lead to an order of magnitude increase in risk. Many aspects of X. fastidiosa disease invasion remain uncertain and hinder forecasting; we recommend future studies investigating quantification of the infection growth rate, and short and long distance dispersal."