A recent study highlights the potential of mathematical modeling in preparing for future plant disease invasions, with a focus on citrus greening disease, also known as huánglóngbìng (HLB). This bacterial disease is considered the most damaging threat to citrus crops globally, with devastating impacts already observed in major citrus-producing regions like the United States and Brazil.
Since 2005, citrus production in Florida has declined by 80%, with estimated annual losses of over $3 billion to the U.S. citrus industry. While Europe remains unaffected, the discovery of psyllids—an insect vector for the disease—in citrus-producing countries such as Portugal and Spain has raised concerns about a potential outbreak. Spain, being Europe's largest citrus producer and the sixth largest globally, faces significant economic risks if an infestation were to occur.
Modelling strategies for early detection and disease control
A new study by researchers at the University of Cambridge explores how mathematical modeling can guide detection and control strategies for citrus greening in Europe. Published in Plants, People, Planet on 24 February 2025, the research suggests that early detection, including the identification of non-symptomatic infections, combined with effective pest management, is essential for minimizing the impact of the disease.
The study indicates that once citrus greening enters the European Union, large areas could become infected within 10 to 20 years without intervention. Even with visual surveillance in place, initial detection could occur after the disease has already spread extensively, making eradication unlikely.
While removing infected trees and applying insecticides could extend the viability of citrus farming for at least a decade, the research points out that effective control measures might require chemical use exceeding the limits currently authorized by EU regulations. The study concludes that strategies focused on identifying non-symptomatic infections would be the most effective.
One potential early-warning measure involves testing psyllids for the presence of the bacteria responsible for citrus greening. Detecting infected insects could enable quicker responses, reducing delays in implementing management measures.
Using modeling to anticipate future plant disease threats
The study illustrates how mathematical modeling can be used to anticipate plant disease invasions and inform policy decisions. According to Professor Nik Cunniffe, head of the Theoretical and Computational Epidemiology group at the University of Cambridge, predictive modeling helps integrate various uncertainties and offers insights into the potential spread, detection, and control of complex biological threats.
Implications for European agriculture and future research
The findings underscore the importance of early detection in controlling citrus greening in Europe. Current research predicts that without timely intervention, widespread infection could occur quickly, posing a threat to citrus production across the region.
Following this initial study, the University of Cambridge is extending its modeling work under the leadership of PhD researcher Laura Erbetta. The research aims to adapt the citrus greening model for other regions and disease vectors, particularly focusing on the Asian citrus psyllid, which has recently been detected in Cyprus.
For more information:
University of Cambridge
Tel: +44 01223 333900
Email: info@plantsci.cam.ac.uk
www.plantsci.cam.ac.uk