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Non-native Species News: Issue 8

Last edited: 25 October 2022
Author: NNSS

PDF version


Welcome to Issue 8 of Non-native Species News: Autumn 2022

Thank you to everyone who has contributed to this newsletter. All links in this newsletter are external and a pdf version is available.


Asian hornet

An Asian hornet nest was recently found and destroyed in the Rayleigh area of Essex. A second credible Asian hornet sighting was reported in the Dover area of Kent. National Bee Inspectors carried out enhanced surveillance in Dover but no further insects were seen. Find out more on the website of the National Bee Unit.

We would be grateful for your support in helping to raise awareness and encourage reporting of any further sightings, particularly in the Essex and Kent areas. Any suspected sightings should ideally be reported via the Asian hornet watch app or the online reporting form, visit the Asian hornet alert page for links to these and awareness raising materials. 

GB Strategy

The updated GB Strategy is expected to be published in winter 2022.

NNS Inspectorate

Find out more about the work of the Non-native Species Inspectorate, and contact the Inspectorate.

Pathway work

A working group is developing a pathway action plan for horticulture. Draft Pathway Action Plans for angling, recreational boating and zoos can be found on our website. All of the action plans will be subject to a public consultation shortly.

Local Action Group workshop

The next Local Action Group workshop will be held in early 2023. Please contact us to be added to the mailing list for more information.

Update to list of IAS of Union Concern (EU only)

On 13 July 2022, the European Commission added a further 22 species to the list of species of Union concern in the EU – see Commission Implementing Regulation 2022/1203 (external link). For most of these species the associated restrictions and obligations came into force on 2 August 2022. Note: These additions are for the EU only and do not apply to GB.


This autumn we are encouraging gardeners to dispose of garden waste responsibly when clearing the garden. Please help us to raise awareness, social media graphics are available in landscape and square versions, and free leaflets and posters can be provided.

Beware of Aliens! European communications campaign launched

A series of materials including posters, animations and social media graphics have been developed through a European Commission-funded project to raise awareness of invasive alien (non-native) species in Europe. The project was led by the UK Centre for Ecology & Hydrology (UKCEH) and the Atlantic Technological University, Ireland, and involved government agencies, trade organisations, NGOs and research institutes across Europe. Materials are freely available to download and share, view the materials on the project website.

Updates from non-native species projects

Tees Rivers Trust: Bring on the Biocontrol

Chloe Lawrence, Tees Rivers Trust

Last year, Tees Rivers Trust continued its mission of combating invasive species with an innovative project to release several biological control agents on Himalayan balsam sites within the Tees catchment. The rust fungus biocontrol aims to be a long term and self-sustaining method of managing Himalayan balsam, by weakening the stands, reducing seed production, and therefore allowing native species to re-establish. With what started as 1 successfully established site in 2019, the trust increased to 12 sites in 2021, and now a further site this year across the Tees Catchment.

Working with CABI, we have now seen that all the sites from last year have successfully overwintered, infecting this year’s seedlings which is really promising for the goal of long-term establishment.

Totalling 13 biocontrol sites in the Tees catchment, our aim is to get funding for more sites, encouraging the biocontrol to spread throughout the whole catchment along the river Tees.

If you would like more information about Tees Rivers Trust’s work on biological control or have any questions please get in touch with Chloe Lawrence: chloe@teesriverstrust.org or check out our website.

Image shows Himalayan balsam leaves infected with the rust fungus bio-control. 

Ecosystem Invaders

Tomos Jones, WaREN

The National Eisteddfod in Wales is reportedly the largest cultural festival in Europe. It’s for this reason that the Wales Resilient Ecological Network (WaREN) and Stand for Nature Wales projects decided to attend and join forces: we didn’t want to be ‘preaching to the converted’ at an environmental event. We had a shared theme of the nature crisis, with WaREN focusing on invasive (non-native) species as one of the ‘top five’ causes of the nature crisis.

WaREN was promoting its Ecosystem Invaders campaign with an aim of increasing awareness of invasive species and their impacts in Wales. During the campaign we’ve been promoting ‘Be Plant Wise’ and ‘Check, Clean, Dry’ but developing our own campaign materials including leaflets, explainer clips, weekly quizzes and bilingual ‘top trumps’.

Our stand at the Eisteddfod was located in the Science Village. Here we had to compete for attention with a (self-identifying) crazy scientist and his exploding balloons but we still engaged with nearly 1,500 people! That is direct engagement, almost all of who were families completing our invasive species activities. These included an eDNA activity - with a fantastic PCR machine made of recycled cardboard boxes - and an invasive species hunt. We also had invasive species cartoons for colouring. While the children were busy (and learning) we could ‘hook’ the adults to ask if they’d heard of invasive species and biosecurity…

Find out more on the Waren project webpage, campaign website or by contacting Tomos Jones. Please check out our partner pack which includes campaign materials and a collection of invasive species quizzes!

Canal & River Trust Invasive Species Eradication Project 2021 to 2025

Charles Hughes, Canal & River Trust

The CRISEP 2021 – 2025 is a strategic partnership project between Severn Trent and the Canal & River Trust. Severn Trent are providing £600,000 worth of funding to support the Trust in eradicating four invasive plant species throughout the Severn Trent supply area. The target species for this project includes Japanese Knotweed Fallopia Japonica, Giant Hogweed Heracleum mantegazzianum, Floating Pennywort Hydrocotyle ranunculoides and Water Fern Azolla filiculoides. This project is the largest of its kind on UK inland waterways covering a treatment area of up to 250km of waterway.

In year 1, a total of 195km lengths of waterway impacted by INNS underwent treatment. Chemical control (including stem injection) was conducted in the summer of 2021 for 226 sites of Japanese Knotweed and 73 sites of Giant Hogweed. A GIS mobile survey was developed to accurately record and map all treated terrestrial invasive plant sites allowing for field data to be captured including methods used and site photography. A first-of-its kind trial was also conducted for Himalayan Balsam Impatiens glandulifera. This was conducted at Penarth Feeder, hydrologically linked to the Montgomery Canal (SAC/SSSI). The trial involved the use of dredging’s placed on top of hessian matting and hydroseeding the area using native wildflower and grass seed mix (see image above). This trial will hopefully help achieve biodiversity and environmental net gain on site.

For the aquatics, a total of 11km of waterway underwent treatment for Floating Pennywort and 10km for Water Fern. This included the use of mechanical removal techniques for Pennywort using specialised boats in combination with post-chemical control. This work has also helped to improve the condition grade for important designated sites such as SSSIs and SACs. A biocontrol using Stenopelmus rufinasus for Water Fern also proved largely successful with 58% of sites showing either complete or near complete reduction of the plant. For more information visit the website.

Fens Branch Canal – mechanical removal of floating pennywort (before and after)

New Yorkshire and North West Environmental Project Officer

Richard Atkinson, British Canoeing

British Canoeing are delighted to welcome Jake Crone to the Places to Paddle Team as the Yorkshire and North-West Environmental Project Officer. The new post has been funded by Defra until April 2023 to help manage floating pennywort in Yorkshire and the North-West of England with partners including the Environment Agency, Canal and River Trust, Angling Trust and affiliated BC paddling clubs.

Voluntary floating pennywort removal event – Northlands Park, Basildon

Drew Chadwick, Angling Trust

Once again, another fantastic voluntary Floating Pennywort removal event, facilitated by The Angling Trust, took place at the popular country park, Northlands Park, Basildon, Essex. Partnership working between anglers and paddlers made light work of removing over 35 Tonnes of floating pennywort in a day! Lots of engagement took place with the public. Everyone who showed an interest or asked questions went home with a waterproof INNS ID guide – ultimately increasing INNS awareness.

S&A Watercraft have the fishing rights on many waters across Basildon and have been making a huge difference with the environmental work they have been carrying out. If it wasn’t for their hard work on regular work parties, this small, shallow Stillwater would be completely covered with floating pennywort, thus resulting in a huge decline of angling and other recreation water-based activities.

Sam from S&A Watercraft said “it is fantastic to see so many volunteers giving up their free time on a Saturday to carry out environmental work. This shows how powerful the partnership working is between anglers and paddlers, as we all share the same passion for our waterways”

A special thanks goes out to all the volunteers who helped on the day, especially The Angling Trust, S&A Watercraft, Whoosh Explore Canoe Club, British Canoeing, Basildon Council, and the many anglers who helped on the day. Find out more about the Floating Pennywort Strategy.

Scottish Invasive Species Initiative – Scottish Ministers visit and demonstrating success on a site-by-site basis

Callum Sinclair, Scottish Invasive Species Initiative

The Scottish Invasive Species Initiative has been controlling a suite of invasive non-native plants across the north of Scotland since 2018.  Target species are pretty much the usual suspects – giant hogweed, Himalayan balsam, Japanese knotweed and American skunk cabbage. The trick with the control of many invasive non-native plants is to maintain ongoing control to finish the job.  To continue control needs resources and funding is essential to supply these resources.  Many initially successful invasive species control projects have got off to flying starts, made great progress and then ran into a funding brick wall, saw their work undermined and gains made slowly (or quickly!) eroded.

To make the case for future funding it is essential that control schemes show the impacts and benefits of their work in each phase of delivery and so demonstrate that genuine progress is being made.  The Scottish Invasive Species Initiative manages invasive plants over many 100’s of kilometres of riverbank and identified sites. We record the abundance of the plant being controlled each year, the volume of chemical applied, the hours taken to deliver control and take site images at fixed points – all of these measures help us to record and show change on a site-by-site basis.

As we come to the end of the current funding cycle – our funding from National Lottery Heritage Fund Scotland and NatureScot ends in March 2023 – we have been preparing a number of site specific case studies to report on progress made across a range of our target species and sites.

These studies allow us to:

  • Report change in effort (measured by hours of control and chemical volumes required) to complete annual control,
  • Show change in plant abundance (measured by DAFOR scale – Dominant, Abundant, Frequent, Occasional, Rare – monitoring and photography at fixed points),
  • Assess ongoing and predicted future management to inform discussions with partners, land managers and funders

Giant hogweed monitoring point at Inglesmaldie on River North Esk in Angus in 2019 (left) – ‘dominant’ abundance and 2021 (right) ‘occasional’ abundance

Obviously not all invasive non-native plant species respond equally to treatments.  Often rapid progress can be made in the control of Japanese knotweed e.g. at Aberfeldy on the River Tay where the infestation went from ‘abundant’ to ‘rare’ after 2 years of control and time and chemical volumes required to deliver control dropped by >90% in the same period. 

However, giant hogweed control is a long term commitment (due to seeds in the soil seedbank from previous flowering remaining viable for many years - perhaps up to 10 years) e.g. control on the Muckle Burn in Moray  where the species remains ‘dominant’ in abundance (though with a different age class profile) whilst the hours spent to and volume required to control have reduced by 80% and 69%.  Progress at Inglesmaldie, River North Esk has been more rapid with the plant now being ‘occasional’ in abundance (where previously it was ‘dominant’) and >90% reductions in time and chemical volume to control recorded.

So, do have a look at how we have approached the reporting of progress at some of our sites.  We hope these studies will help to persuade the funders of the future that supporting ongoing invasive non-native plant control programmes isn’t simply pouring money into a black hole.  With good organisation and coordination, strategic planning and effective and pragmatic monitoring we can show that progress is being made and that the war on these plants is winnable.

We were delighted to welcome Lorna Slater, Minister for Green Skills, Circular Economy and Biodiversity, to visit us at Aberfeldy on the River Tay in July and to be able to show and tell her about our work with volunteers to control Japanese knotweed and giant hogweed there.

Mark Purrmann-Charles and Jane Hamilton from the project team, Iain Sime from NatureScot (lead partner) and volunteers from the Upper Tay Paths Group (our local community partner in Aberfeldy) were able to discuss the need for long term management of invasive species in order to make lasting progress and how the training, support and coordination has been essential to progress here. Ms Slater seems to be impressed by what she saw – commenting on twitter that “The SISI project are doing fantastic work eradicating invasive species. It was really good to get out and see some of their sites today and meet their wonderful volunteers.”

It’s always great when we get the chance to share and show Ministers and others our approach to invasive species management – which relies on a small committed project staff, a network of local delivery partners and an army of dedicated and enthusiastic volunteers.  Working across 1/3rd of mainland Scotland that combination of effort is essential if we are to tackle the threats to our native biodiversity presented by invasive non-native species in Scotland.

As an added bonus we were also delighted to meet again with Mairi Gougeon, Cabinet Secretary for Rural Affairs and the Islands on her visit to our partner the River Deveron, Bogie and Isla Rivers Charitable Trust in August. We “treated” Ms Gougeon to a morning of torrential rain with us in 2019 so it was fantastic to get the chance to catch up with her on our progress since then – in the dry! Find more information on the Scottish Invasive Species Initiative on our website, on Twitter, Facebook and Instagram.

Quick links

For more information on non-native species please visit www.nonnativespecies.org. You can also follow our awareness raising campaigns on Twitter @CheckCleanDryGB and @InvasiveSp.