Plant pests and pathogens present a significant risk to global plant health and this threat is ever rising due in large to the growing global trade of plant material and, increasingly, evidence suggests that climate change is influencing pest establishment in new locations. Countries are using a number of phytosanitary measures in order to try and reduce this risk, including the use of Pest Risk Analysis (PRA) which assesses the potential impact a species could have on plant health were it to be introduced into a new region; thus identifying quarantine organisms.
A prominent issue in identifying and assessing plant health risks is that the most serious invasive alien species are often not pests in their region of origin, either because they are controlled by natural enemies that do not occur in the region of introduction, or because their original hosts are more resistant to the pest than the newly encountered host plants. A prime example of this is the emerald ash borer which is not considered an important pest in its native range, however when introduced to the US decimated ash tree populations there. For this reason the majority of the most damaging alien forest pests and diseases that have or have had a dramatic impact on temperate forests would not have been predicted as pests by conventional PRA.
It is estimated that 30-40% of known plant species are grown in living collections of the more than 3,000 botanic gardens and arboreta throughout the world. Often, species are maintained in gardens not in the country or even on the continent in which they are native. These expatriate plants offer a unique opportunity to understand and predict potential invasive threats to a country’s plant health. They can act as standing sentinels for potentially invasive pests and pathogens. For example, surveying native European plants growing in botanic gardens and arboreta outside Europe, especially in countries with similar climates, offers an excellent opportunity to monitor for damage by non-native pests and diseases. This information can then be used to provide an early warning system by informing plant protection efforts such as PRA; identifying new pest and pathogen risks to a country’s native flora.
Sentinel plants can also provide valuable information which can help:
Botanic gardens and their role in the fight against invasive alien plant pests and pathogens, as well as plant species, is discussed in BGjournal 8 (2) 'Botanic gardens and invasive alien species'. This issue also includes a great write up of the biosecurity work of the Royal Botanic Gardens Melbourne.
The role of the IPSN in safeguarding global plant health
A number of previous studies using sentinel plants in botanic gardens and arboreta illustrate their potential in informing plant health:
- ISEFOR - Increasing Sustainability of European Forests: Modelling for security against invasive pests and pathogens under climate change
- PRATIQUE - Enhancements of Pest Risk Analysis Techniques
- The New Zealand Expats Plant Project
In the spring of 2011 BGCI carried out an electronic survey to learn more about the relevant expertise and policies already in place at botanical institutions around the world. Results revealed a solid foundation of expertise, resources, partnerships and practices that aid in understanding and addressing invasive species problems at individual institutions. However, it also identified a need for more formal or regular training and enhanced communication and coordination among institutions in order to increase the power and impact of the network. Read more about the 2011 survey here
The IPSN will provide a formal structure to be developed under which gardens could act individually and collectively to increase the predictive power of their collections, and engage other partners who can use this information.