|Passiflora edulis (highly invasive in the tropics)|
Every day, hundreds of different plant species -- many of them listed as invasive -- are traded online worldwide on auction platforms. This exacerbates the problem of uncontrollable biological invasions as they are often introduced as ornamental plants. Those in turn spread into the wild, where they now threaten the native flora. The vast majority of invasive species can be easily obtained with just a click of the mouse.
To get an estimate of how much of the global trade in invasive plants is actually done online, a group of researchers at the ETH Zurich monitored online trade on eBay and nine other online trading platforms.
For 50 days, the researchers tracked which plant species were offered for sale in various countries, and how often. They used a software specifically developed for the study taking advantage of the fact that all online platforms make sale listings accessible to external software build to systematically search for and analyse online content. All findings were crosschecked against common lists of invasive plants, established by various institutions such as the International Union for the Conservation of Nature (IUCN).
Over the course of the study the colleagues found 2,625 different plant species offered for sale on eBay. Of those, 510 are known to be invasive in at least one region of the world. And out of that group, 35 are on the IUCN's list of the 100 worst invasive species.
These are astonishing numbers and sellers found in the study were located in 65 countries. Offers to sell invasive species came from 55 of these countries, including Australia. Dealers there offer invasive plants - that are known to be harmful in other parts of the world - on a grand scale. That was unexpected, since the Australians don't allow you to bring any invasive plants across their borders. But surprisingly, there are apparently no controls in place to make sure potentially harmful plants don't leave the continent.
Rules governing the trade in these plants are halfheartedly enforced, if at all. And it's virtually impossible for the dealers to keep track of all the laws and regulations concerning import and export of potential invasive species in different countries. A new threat is also emerging: regions that previously had no access to trade flows can now participate thanks to the internet. South Africa is now showing up on our map. We have no idea whether the plants that are being put on the global market from this corner of world will prove to be invasive species. It may well be that several of them could become invasive in other regions.
The only way to contain invasions is by limiting and monitoring the trade. The study shows that it is theoretically possible to continuously monitor this trade in order to spot newly traded species, which could signal future invasions. Many countries already have sets of rules and regulations in place with the goal of curbing the spread of invasive species.
As online trade blossoms, it makes it even more urgent for the authorities to take action or for responsible large commercial nurseries to adjust their product ranges.