Introduced organisms can have large ecological and economic impacts on their new ranges and the native species which inhabit them. This is never more so true than with plant pests and pathogens. One reason for the high levels of damage seen is that plants, having not evolved alongside these introduced species, have built up no natural resistance. Similarly, it is unlikely that any natural predators will be present to control population sizes. Identifying potential threats to native flora before an organism is introduced can drastically improve the chances of eradication or control/containment programmes, or even better can stop their introduction in the first place. This is where sentinel plants can provide unique benefits to plant health.
Plant species maintained outside of their natural ranges (e.g. as in botanic gardens and arboreta) offer a unique opportunity to understand and predict potential threats to a country’s plant health by acting as standing sentinels in foreign lands. These individuals can be monitored for damage by pests and diseases that, although native to their current location, are non-native and currently not introduced in the host's country of origin. This information can then be used to provide an early warning system and can aid plant protection efforts at a regulatory level (for example within Pest Risk Analysis).
Sentinel plants can also provide valuable information which can help:
- Increase understanding about ‘known’ pests and diseases (e.g. dispersal mechanisms, origin, etc.)
- Identify new pest-host associations (e.g. suggest which species of plant may be particularly susceptible/ resistant to a particular pest)
- Identify potential biocontrols
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
Publications of interest
Britton, K. O., White, P., Kramer, A., & Hudler, G. (2010). A new approach to stopping the spread of invasive insects and pathogens: early detection and rapid response via a global network of sentinel plantings
Roques, A., Fan, J. T., Courtial, B., Zhang, Y. Z., Yart, A., Auger-Rozenberg, M. A., ... & Sun, J. H. (2015). Planting sentinel European trees in eastern Asia as a novel method to identify potential insect pest invaders. PloS one, 10(5), e0120864.