World News – UA – Amsterdam releases 5,000 leaf fleas to stop spread of Japanese knotweed


Five thousand Japanese fleas were released in Amsterdam to control Japanese knotweed, a once famous plant whose roots break concrete now threaten local biodiversity, damage water quality and increase risk of flooding

The Dutch government has taken the unprecedented decision to issue a waiver on the ban on the introduction of alien species in the face of skyrocketing costs associated with invasive species

Japanese knotweed, Fallopia japonica, causes extensive damage to building foundations, sidewalks and dykes in the Dutch capital, costing millions of euros per year Laboratory tests suggest leaf fleas – psyllids Japanese knotweed, or Aphalara itadori – can kill young shoots and potentially stop the plant from growing by sucking up its sap

Initially 5,000 fleas were released at three sites It is hoped that they will successfully hibernate through the winter and become established in the new year. More specimens will be released next spring

Japanese knotweed was introduced and cultivated in the Netherlands as an ornamental plant between 1829 and 1841 by German botanist Philipp Franz von Siebold Discovered next to a volcano, it has been named « the most interesting new ornamental plant of the year ”by the Society of Agriculture and Horticulture of Utrecht

Its aggressive roots, which can grow up to 20cm per day and pierce through concrete or tar, have been a major problem in Europe ever since Amsterdam once considered using fire, hot water and even laser to control the unsuccessful plant growth

Suzanne Lommen, entomologist at the Institute of Biology in Leiden, the southern city where Japanese knotweed was first introduced to the Netherlands, coordinates the trial

She said, “All kinds of things have been tried, but complete pest control is extremely difficult and very expensive. You will have to combine different methods to control Asian knotweed We know from Japanese knotweed psyllid that it can kill young shoots and slow or even stop plant growth by sucking sap – nutrition – from the plant

« If the psyllid can establish, reproduce, and spread, and do the damage we see in breeding trials, it can hopefully inhibit the growth and spread of Asian knotweed. Next, you have a very cheap and ecological solution with many years of effect that you can combine with the more expensive methods « 

The Dutch Food and Consumer Safety Authority (NVWA) concluded that psyllids do not pose a threat to native biodiversity

Jaike Bijleveld, from the municipality, said there were a thousand sites in Amsterdam where the knotweed had settled « It’s a very big problem, but we are working hard on it, » he said. she told the Amsterdam newspaper Het Parool

Lommen said there was a chance that the fleas would not take on the Dutch climate « What we don’t know yet is how the psyllid will thrive in the Netherlands », she said declared « He comes from a region of Japan where the climate most resembles that of the Netherlands. In the laboratory, he feeds on the cross knotweed that grows here But reality will show if he can survive in our country »

Japanese knotweed, Buckwheat, Introduced species, Netherlands, Invasive species

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