Global strategies to manage huanglongbing (HLB) and its vectors: insights and implications for the Mediterranean region

Huanglongbing (HLB), also known as citrus greening disease, poses a severe threat to the global citrus industry. This disease is caused by three species of bacteria, ‘Candidatus Liberibacter asiaticus’, ‘C. L. africanus’, and ‘C. L. americanus’. The primary pathogen vectors are the Asian citrus psyllid (Diaphorina citri Kuwayama, Hemiptera: Psyllidae) and the African citrus psyllid (Trioza erytreae Del Guercio, Hemiptera: Triozidae). The disease is incurable, and its management relies on reducing vector densities and the adverse effects of bacterial infections on host trees. Managing psyllid vectors, especially D. citri, has proven exceptionally challenging due to its rapid spread and subsequent difficulty in containing and suppressing newly detected populations. This article reviews strategies developed to manage HLB and its vectors in different regions of the world with a focus on the challenges likely to be faced by the Mediterranean region. Diaphorina citri has recently invaded the Mediterranean region and T. erytreae has been encroaching via the northern Iberian Peninsula for several years. Currently, HLB has not been detected in this important citrus production area. Therefore, this area must implement preventive measures and proactively prepare for potential invasions by D. citri, T. erytreae, and HLB-causing pathogens by developing and adopting comprehensive management strategies in advance of anticipated invasion events.