Invasives Blog

The GB Non-Native Species Secretariat (NNSS) is once again raising awareness of the need to help prevent the spread and reduce the harmful impacts of invasive non-native plants and animals during UK Invasive Species Week 2024.

Invasive Species Week, which runs from 20-26 May, is also an opportunity for CABI to highlight its expertise in the sustainable weed management of invasive non-native species (INNS).

These include developing safer-to-use and environmentally friendly biological control agents (BCAs) to manage floating pennywort, Australian swap stonecrop, Himalayan balsam, and Japanese knotweed.

Cost to the Great Britain economy an estimated £4bn a year

Last year, CABI scientists carried out a study, published in the journal Biological Invasions, which revealed INNS – such as the aquatic weeds mentioned – cost the Great Britain economy an estimated £4bn a year.

There are currently around 2,000 INNS in the UK with 10-12 new species establishing themselves every year.

The list includes well-known established species such as grey squirrel, killer shrimp, giant hogweed, mink, and parakeets, as well as recently arrived, but highly impactful species such as the sea squirt Didemnum vexillum and ash dieback.

CABI’s expertise on invasive weed management highlighted

Japanese knotweed is one of the most damaging invasive weeds which has become extremely problematic across Europe, including the UK (Credit: CABI).

In this blog to mark Invasive Species Week, we encourage you to look back on these blogs which highlight our work to help tackle the most unwanted invasive aquatic weeds in the UK.

Read in this blog about CABI’s work to try and halt the spread of Himalayan balsam which frequently found along waterways or damp areas, is highly invasive and causes a number of negative effects. Not only does it compete with native plant species for light and space, but, with a high nectar content, it also attracts pollinators such as bees over native flowers. 

Find out more about in this blog how with the Azolla weevil last year marked a century of Azolla biocontrol in the UK in the fight against Azolla filiculoides – otherwise known as floating water fern or fairy fern.

Also see in this blog discover how Japanese knotweed – one of the most destructive of all the invasive species found in the UK, costing the British economy around £165.5m a year – is being tackled with several possible natural agents.

Meanwhile, discover in this blog how a microscopic mite could hold the key to stemming the tide of Crassula helmsii – also known as Australian swamp stonecrop, New Zealand pigmyweed or crassula – which can form vast monocultures across and surrounding waterbodies.

Crassula helmsii waterbody infestation (Credit: CABI).

Finally, in this blog learn more about the floating pennywort weevil (Listronotus elongatus) is the latest biological control method to combat the highly invasive aquatic plant, floating pennywort (Hydrocotyle ranunculoides). 

Additional information

Main image: Himalayan balsam growing alongside River Teviot, Roxborough, Scotland (Credit:Toby Penrhys-Evans, CABI).

UK Invasive Species Week 2024

Invasive Species Week is an annual week of awareness raising and events to help prevent the spread, and reduce the harmful impacts, of invasive non-native plants and animals. Find out more from the website here.

Invasive species

Through its work with donors and partners, CABI is helping to manage the spread of invasive species, a problem that costs the world almost 5% of global gross domestic product or an estimated US$1.4 trillion per year. Find out more here.

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