Blame eBay for global spread of invasive plants

In addition to being a popular marketplace for collectables and rare memorabilia, eBay may also be one of the reasons that invasive flora are spreading globally, according to research published in the latest edition of the journal Conservation Biology.

In the study, Christoph Kueffer, a senior lecturer at the Institute of Integrative Biology at ETH Zurich and his colleagues monitored eBay and nine other e-commerce outlets to see which plant species were offered for sale in various countries and for how often. Their goal was to determine how much of the worldwide trade in potentially invasive plants occurs online.

Kueffer’s team monitored which plant species were offered for sale in various nations over a 50 day span, and reviewed lists of invasive plants from the International Union for the Conservation of Nature (IUCN) and other organizations to see whether the plants up for sale were classified as invasive somewhere in the world.

While the researchers emphasized that they could only monitor offerings and could not prove that transactions were actually finalized, they reported finding 2,625 different plant species for sale on eBay. Of those, 510 were known to be invasive in some part of the world, and 35 were found on the IUCN’s list of the top 100 most invasive plant species on Earth.

A big and easy market for invasive species

The invasive species most often found available for sale was the passionfruit (Passiflora edulis), a species which is highly invasive in the tropics and was found on eBay about 90 times per day. It was offered by dealers from 17 different countries over five major geographic regions, Kueffer’s team discovered.

Second on the list was the cornflower Centaurea cyanus, which was listed an average of 80 times per day by dealers in 10 countries in five regions. While it deemed invasive in some parts of the US, the plant that is listed for sale most frequently, the desert rose Adenium obesum, has not yet been found to be an invasive species. It was put up for sale more than 3,100 times per day.

“We didn’t expect the global trade in plants that are known to be invasive to be so extensive,” said lead author Franziska Humair, also from ETH Zurich. “To put it briefly, the vast majority of invasive species can be easily obtained with just a click of the mouse.”

Regulations governing the buying and selling of these plants are poorly enforced, and it is virtually impossible for dealers themselves to monitor all of the laws used by different countries to prevent the spread of invasive flora. Even Australia, which has a strict set of laws preventing the influx of invasive species, was found to be a sizable source of plants being exported to parts of the world where they could be invasive, they found.

“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,” Kueffer said. “The only way to contain invasions is by limiting the trade in potential invaders,” he added, noting that it was “urgent for the authorities to take action” to prevent the spread of potentially harmful plant species.

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