The Global Plant Trade Is Spreading Invasive Species To Europe

(MENAFN- The Conversation) Back in 2016, one of us (Silviu Petrovan) was asked to identify a live frog found in a shipment of roses in Sheffield, England. It certainly wasn't any species found in Europe: Silviu thought he had been pranked.

But with help from Ecuadorian and Colombian scientists, he was soon able to identify it as a North Andean tree frog. This species is found only in a few areas in the highlands of Colombia including, crucially, a region known for its flower-growing.

This sudden realisation that cut flowers are being shipped from Colombia via Ecuador to Britain, potentially with hitchhiking animals in tow, sparked a collaborative project to investigate the complexities in this increasingly global trade.

Initially, we explored the risks that invasive species will establish themselves. For instance, the recent fashion for old potted olive trees in restaurants, typically imported from farms in Italy and Spain, is a risk because these trees can serve as vehicles for species like the Italian wall lizard.

Sometimes called the Italian ruin lizard (scientists call it Podarcis siculus), the lizard is spreading throughout Europe , with introductions often linked to the ornamental olive tree trade.

But the global trade in cut flowers, pot plants, bulbs and foliage was worth around US$25 billion (£20 billion) in 2022, and it has many other environmental and social risks.

As well as the spread of pests and invasive species, these include wild plants harvested illegally, and a range of effects on people including threats to food security or access to clean water. In our new paper, published in the journal Bioscience , we examined these risks and how we can mitigate them.

We combined a review of published research on risks related to the ornamental plant trade with analysis of data on illegal trade and the prevalence of pests and hitchhiking vertebrates in plant shipments.

That included two databases of customs interceptions of organisms such as insects, slugs and snails in imports into the UK and the Netherlands, and two databases of records of amphibians and reptiles linked to UK and Netherlands imports of ornamental plants.

Despite repeated attempts and contacts, it was impossible to secure official data on contaminant interceptions from other major ornamental plant importer countries. Nonetheless, the available data provided an important snapshot of what might be occurring more widely.

Our analysis shows that the ornamental plant trade is rapidly changing, doubling in value in recent decades. More and more cut flowers are being imported from tropical areas such as east Africa and South America, where the industry can play an essential economic role . Despite the risks we identify, these industries can and do bring significant benefits to people, and we are not calling for a halt to the trade.

However, even with only two years of interception data it is clear that ornamental plant shipments contain considerable volumes of pests and potentially invasive organisms. Furthermore, while a range of species were found, taxonomic identification was not always possible, with around 20% of contaminants not being identified to species level.

In some cases data named a contaminant only as“Coleoptera”, the scientific name for beetles and the largest insect group comprising over 300,000 species, or as“Lepidoptera” (butterflies and moths). These uncertainties make it harder to accurately assess invasive species risks.

The reports of amphibians and reptiles imported into the UK and Netherlands are relatively small in number, dozens annually. But this is most likely a substantial underestimate given that these are not records systematically collected by authorities but rather mainly chance discoveries in airports, shops, depots and private homes, which then get collated because they are re-homed by specialist exotic wildlife centres.

The numbers of illegal plant seizures were generally small, even though there is likely to be a large illegal trade in plants such as orchids or cacti.

This suggests that this is an underreported aspect of the illegal wildlife trade, due to less awareness and attention paid to plants. It's hard for the layperson to tell a legal cactus from an endangered one, whereas it's pretty obvious a rather colourful lizard found on a pot plant in Britain should not be there.

Importantly, we also highlight growing concerns about the allocation of resources, in particular water and land, including the loss of Indigenous grazing land to ornamental plants.

The use of pesticides for this non-essential crop type that has no nutritional value for people or livestock, in countries which might lack sufficient infrastructure to deal with the potential pollution, is also something that requires careful consideration.

Ornamental plants are valuable products in global trade. Their trade is dynamic and shifting, yet while they are undoubtedly important in terms of their economic value, it is essential that the risks to people and the environment are not overlooked.

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