Koh, Joshua, Cunnifee, Nik and Parnell, Stephen

Following the discovery of a quarantine plant pest or disease, delimitation is urgently conducted to define the boundaries of the infested area, typically through surveys that detect the presence or absence of the pest. Swift and accurate delimitation is crucial after a pest or pathogen enters a new region for containment or eradication. In this study, we used an individual-based model to simulate the spread of Huanglongbing (citrus greening), a priority EU pest, and evaluated three delimiting strategies across various host distribution landscapes. We found that an adaptive strategy was most effective, especially when tailored to the polycyclic nature of the pest. This underscored the need for specific delimiting approaches based on the epidemiological characteristics of the target pest.

Scientific Reports. February 2025

Developing epidemiological preparedness for a plant disease invasion: Modelling citrus huánglóngbìng in the European Union

John Ellis, Elena Lázaro, Beatriz Duarte, Tomás Magalhães, Amílcar Duarte, Jacinto Benhadi-Marín, José Alberto Pereira, Antonio Vicent, Stephen Parnell, Nik J. Cunniffe

Huánglóngbìng (HLB) is a bacterial disease of citrus that has significantly impacted Brazil and the United States, although citrus production in the Mediterranean Basin remains unaffected. By developing a mathematical model of spread in Spain, we tested surveillance and control strategies before any future HLB entry in the EU. We found while some citrus production might be maintained by roguing, this requires extensive surveillance and significant chemical control, perhaps also including testing of psyllids (which spread the pathogen) for bacterial DNA. Our work highlights the key importance of early detection (including asymptomatic infection) and vector control for HLB management.

Plants, People, Planet. February 2025