The risk of rapid ʻōhi’a death to Aotearoa New Zealand and the South Pacific

Résumé fourni par la source

The genus Ceratocystis includes several invasive pathogens that have caused severe disease in native and cultivated plants following introduction into new regions. Rapid ‘ōhi’a death (ROD), resulting from infection by C. lukuohia and C. huliohia, has caused widespread death of Metrosideros polymorpha (‘ōhi ‘a lehua) in Hawai’i since its detection in 2010. Should these pathogens be introduced into Aotearoa New Zealand or other South Pacific nations, they have the potential to infect Metrosideros spp. and other plants, including important crops. Presence of susceptible Metrosideros spp. across the Pacific, combined with extensive tourism and trade networks, could facilitate a stepwise spread of the pathogens. Movement of people and goods, including contaminated soil and plant materials, represents a primary dispersal pathway. Biological factors, including associations with ambrosia beetles, may further influence pathogen spread. Preliminary observations suggest several Metrosideros spp. endemic to Aotearoa New Zealand are susceptible, and asymptomatic infections could allow undetected pathogen movement. Climate modelling suggests that regions of Aotearoa New Zealand, particularly the North Island, provide suitable conditions for ROD establishment. Unknowns include host susceptibility, beetle vector ecology, and the diversity of Ceratocystis already in the region. Weather variation may intensify this risk by expanding the pathogens’ geographic and host ranges and altering interactions among hosts, pathogens and insects associated with their spread, including ambrosia beetles. This review emphasises the importance of ongoing research, surveillance, and preparedness, particularly with the absence of curative treatments, to mitigate the potential impacts of ROD in Aotearoa New Zealand and the wider South Pacific.

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