"Optimal strategies for controlling pathogen outbreaks and pathogen evolution towards virulence"Trevenen, ElizabethDeploying cultivars with resistance genes is an economical and effective method for managing pathogen outbreaks, but is subject to a trade-off where more effective control often accelerates pathogen evolution towards virulence, resulting in resistant-breaking pathogen strains (durability-effectiveness trade-off). Spatially and temporally coordinating the deployment of these genes across an area may mitigate the impact of this trade-off. However, previous research on optimal cultivar deployment strategies has often overlooked the dynamic nature of agricultural landscapes, where cultivar deployment can vary over space and time. Using a novel spatiotemporal model, we explored whether the management of epidemics and the durability of resistant genes could be improved by temporally and spatially coordinating the deployment of four resistant crop cultivars, each carrying one resistant gene, into a landscape. We also examined the effects of varying the initial conditions and the dispersal kernel related to the pathogen, and compared these strategies to ones where an additional non-susceptible crop was integrated among the cultivars, a practice that is currently widely used to control pathogen outbreaks. We generally found a durability-efficiency trade-off among our deployment strategies, especially when initial virulence frequencies were high. Rotating cultivars every five years proved to be the most effective strategy for resistance durability. However, the control effectiveness of this strategy was heavily influenced by the spatial arrangement of the cultivars within each rotation, with coordination across the whole landscape providing the best balance between durability and effectiveness. Introducing non-host crops consistently reduced disease incidence and enhanced resistance durability, even at low levels. Our study highlights the need for coordinated spatial and temporal planning at the landscape level when using resistant cultivars for effective disease management. |
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