It’s become an all-too common tale – an introduced insect takes hold in a new home and then it spreads. This wreaks havoc with ecosystems and economies. Take for instance, the emerald ash borer, an Asian beetle first spotted in North America in 2002. Researchers estimate that it has killed hundreds of millions of ash trees and caused more than $10 billion in damage.
In a bid to prevent such catastrophes and getting an early warning of which exotic pests are likely to cause trouble, researchers from across the globe are trying a new approach. They are planting ‘sentinel trees’ from their own regions in distant nations and then observing which insects attack. The findings should help authorities recognize problems more quickly and snuff them out. To many researchers, sentinel trees are the ‘new frontier’ in fighting forest pests.
Already groves of North American and European trees planted in China have enabled scientists to identify and start to study more than a dozen of insects of concern. In Europe, 23 nations have launched a project that will, among other activities, establish sentinel nurseries in North America, Asia and South Africa. This will enable researchers to plant trees from those areas in Europe.
A team led by entomologist Alain Roques of France’s National Institute for Agriculture, Food and Environment pioneered the approach between 2007 and 2011 when it planted seven tree species in Fuyang and near Beijing in China. By 2015 the researchers had identified more than 100 kinds of insects that had sampled the trees. They considered five species to be dangerous, and they took one, a bagworm moth, back to Europe to study its appetite for broadleaved trees. That study showed that the moth can destroy numerous trees.
Researchers in China discovered a beetle demolishing American sweetgum trees planted near Shanghai. Sweetgum is an ecologically and economically important tree species in the Southeastern United States. If the beetle gained foothold in North America, it could pose a serious threat. The discovery prompted China to ban imports of the tree to avoid further damage.
The Chinese researchers planted more sentinel groves in the Fujian province. They have also established two additional plantations, which hold pines, oaks and citrus trees in the Yunnan and Shandong provinces. They plan a fourth in the Liaoning province. As a result, the researchers have discovered eight insect species of particular concern. Such studies can alert authorities to look for pests, some of which were unknown to science, and lead to better-monitoring traps and control measures.
As a result of these findings, funding agencies are ramping up support for sentinel orchards in foreign nations. The understanding is that it could take years to know whether sentinels provide useful intel. Some insects don’t attack young trees, for example. Sometimes, therefore, researchers have to wait for a tree to mature to see the effects of these ‘pests’. Of course, governments are still figuring out how they might incorporate any findings into biosecurity policies and practical actions.
We hope this article has helped you learn a bit more about sentinel trees and their impact on biological research. We strive to bring you information and education each and every week.
