Potted olive snakes are ‘tip of the iceberg’ of ornamental plant trade dangers, researchers say

Ornamental olive trees imported for sale in the UK, some of which are over 100 years old, have plenty of hiding places between their finicky bark and soil during transport. This is very dangerous in terms of importing pests. Credit: Silviu Petrovan/University of Cambridge
Continental snakes, geckos and Italian wall lizards have migrated unnoticed to northern Europe, along with ornamental olive trees imported for gardens and green spaces.
These hitchhiking invaders can become invasive pests that cause significant damage to the natural environment, even on previously snake-free Mediterranean islands such as Mallorca.
These are also red flags for larger problems. This means that a wide range of potentially serious agricultural and environmental pests in ornamental plants and cut flowers are being unwittingly imported into the UK and mainland Europe simply because they are difficult to detect in large quantities and quickly. It means that there is. Transport of plants.
In a study published in the journal Bioscience, researchers found that despite regulations and border checks, imported cut flowers and potted plants pose an increased risk because the volume of trade makes monitoring and control difficult. states that they are doing so. Insects, fungi, reptiles, spiders, and various agricultural pests are transported alive around the world on ornamental plants destined to brighten up our homes and gardens.
They say the multibillion-dollar global market for ornamental plants is rapidly growing and expanding geographically, and improved standards are urgently needed.


The seeds of plants are accidentally brought to Europe in the soil of imported potted plants like this bonsai. After a few weeks of just light, water and nutrients, many other plant species appeared in the pots. Credit: Johan van Valkenburg
Climate change means that disease-carrying insects such as mosquitoes that would have arrived in Northern Europe decades ago and died in the cold may now survive. Also, some ornamental plants themselves can become invasive pests depending on changing growing conditions.
āThe ornamental olive trees sold in the UK are over 100 years old and have lots of hiding places between their finicky bark and transported soil. This is extremely important in terms of imported pests. “This is dangerous,” Professor William Sutherland said in the paper. The Department of Zoology at the University of Cambridge was involved in this research.
He added: “Adult snakes and lizards are just the tip of the iceberg. Even if they do get through, what are the chances that we’ll find small insects or fungi that actually cause problems? It is inconceivable that we will be able to thoroughly check the ecology of this species,” he added. For example, we import 1 million roses from Kenya. ā
āWith huge amounts of cut flowers and ornamental plants being traded rapidly around the world, it is extremely difficult to stop all the pests and diseases they carry, even with the best of intentions. , unwanted hitchhikers are constantly passing through customs import inspections,” said Dr Silviu Petrovan, a researcher in the Department of Zoology at the University of Cambridge and lead author of the paper.
Suppliers do not always operate in compliance with the law. Orchids and cacti are among the high-value plants that are sometimes illegally stripped from their tropical habitats and included in shipments. Regulations that prevent trade in protected wild plants are difficult to enforce at scale.
āDespite the global trade in cultivated ornamental plants, there is still a market for rare species collected from the wild, and this is only likely to lead to rapid species decline. “This could lead to an increased risk of wild pests and plant diseases entering the supply chain,” said Amy, a researcher at the Oxford Martin Program on Wildlife Trade at the University of Oxford, who worked on the study.ć»Dr. Hinsley said.


European tree frogs are often accidentally imported into the Netherlands along with flowers. With huge quantities of cut flowers and ornamental plants rapidly being traded around the world, it is extremely difficult to stop all the pests and diseases they carry. Credit: University of Cambridge
Petrovan, a frog expert, became interested in the subject when he was asked to find live frogs among the roses of a Sheffield florist. At first, he didn’t realize it was a European species and thought it was a prank. He was stunned when he realized that it was a tree frog that must have arrived from Colombia via Ecuador with cut roses.
“Finding a South American tree frog in a flower shop in Sheffield was unusual. It’s hard to imagine this kind of fragile little vertebrate arriving alive in a flower shipment unnoticed by customs. “We realized how difficult it is to deal with ‘very small agricultural pests and their eggs,'” Petrovan said.
The lack of a comprehensive international database on the types and numbers of pests found on imported ornamental plants makes it difficult to fully assess the extent of the problem. To get a snapshot, the team analyzed records of pests found on ornamental plants at Dutch customs from 2017 to 2018, and reported to DEFRA in the UK from 2021 to 2023. In both cases, more than 80% of the pests captured were insects.


Despite regulations and border checks, imported cut flowers and potted plants pose an increased risk as the volume of trade is difficult to monitor and control. Insects, fungi, reptiles, spiders, and various agricultural pests are transported alive around the world on ornamental plants. Credit: Naaldwijk Rijksoverheid


Researchers say these adult lizards are just the tip of the iceberg. If it passes customs import inspection, what are the chances of finding a small insect or fungus that actually causes the problem?Credit: Felix Verschoor Ravon
Beyond pests
The study highlights a number of other environmental and health issues related to the global ornamental plant trade, particularly in the countries where they are grown. These include:
Microplastics and pesticides that have a negative impact on the environment enter soil and water systems during the growth process. Pesticide residues pose a health risk to those who handle cut flowers. The large amounts of water required to grow flowers could originally be used to grow food. For example, Kenya’s floriculture industry is responsible for up to 98% of the water withdrawn from major lakes like Lake Naivasha. Concerns have also been raised about the ability of supplying countries to meet their own agricultural needs. The carbon footprint of cooling and transporting cut flowers across continents is estimated to be as much as 3kg of CO2 per flower. A large number of plants are harvested from the wild, including endangered cacti, succulents, and orchids.
However, this is not necessarily the fault of an industry that employs so many people. The ornamental plant trade is important to economies around the world and supports many rural people and their families. In 2022, exports of cut flowers and leaves were $10 billion, and exports of live plants and bulbs were $13 billion.
“We definitely don’t want to encourage knee-jerk reactions that may be well-intentioned but actually create more problems than they solve,” Petrovan said. .
He added: “We need to push the industry to become more sustainable, including through improved certification and regulation, and work with industry stakeholders to better understand risks and how to mitigate them.” .
Alice Hughes, a researcher at the University of Hong Kong who also took part in the study, said: “We need to be responsible consumers. Certification standards are being developed, but it’s important to buy plants rather than cut flowers. “And we can reduce a lot of the risks that come from that.” They last longer than imported cut flowers and reduce emissions costs. ā
Further information: Amy Hinsley et al, Understanding the risks and impacts of the global ornamental plant trade, Bioscience (2024). DOI: 10.1093/biosci/biae124
Provided by University of Cambridge
Source: Potted olive tree snakes are ‘tip of the iceberg’ of ornamental plant trade hazards, researchers say (January 16, 2025) https://phys.org/news/2025-01 Retrieved January 16, 2025 from -snakes-potted-olive tree-iceberg.html
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