CABI scientists are stepping up the fight against one of the UK’s most invasive non-native aquatic weeds.
Approval has been given for the release of a novel biological control agent – the mite, Aculuscrassulae – to assess its ability in the real-world environment to suppress Australian swamp stonecrop (Crassula helmsii), also known as New Zealand pigmyweed. This follows carefully controlled laboratory testing to ensure the safe, controlled release of the mite in the UK.
The poisonous Parthenium hysterophorus plant is one of the world’s most destructive invasive plant species, threatening biodiversity, food security and human health across numerous countries. The herb is native to Central and South America but has spread to over 40 countries over recent decades including Australia, India, Ethiopia, Swaziland and South Africa.
26 August 2014 – From today, not-for-profit research organization, CABI, will be releasing a rust fungus at locations in Berkshire, Cornwall and Middlesex as part of field trials to control the non-native, invasive weed Himalayan balsam (Impatiens glandulifera) using natural means.
Himalayan balsam has rapidly become one of the UK’s most widespread invasive weeds, colonizing river banks, waste land, damp woodlands, roadways and railways. The Environment Agency estimates that the weed occupies over 13% of river banks in England and Wales. It can reach over three metres in height and competes with native plants, reducing biodiversity. Large scale chemical and manual control is often not feasible and not economically viable.
Using existing measures, the Environment Agency estimates it would cost up to £300 million to eradicate Himalayan balsam from the UK.
The release of the rust fungus comes after an eight-year research programme funded primarily by Defra and the Environment Agency, with contributions from Network Rail, the Scottish Government and Westcountry Rivers Trust. During the course of the research, testing in quarantine laboratories has established that the rust fungus causes significant damage to Himalayan balsam and does not impact on native species.
Introduced to Britain in the 1980s through the aquatic trade Hydrocotyle ranunculoides, commonly known as floating pennywort, is rapidly spreading through Europe and particularly in the UK, Belgium, Germany, Italy, France and the Netherlands. Originating in Central and South America, this stoloniferous perennial plant is forming dense, impenetrable mats which rapidly dominate water bodies, outcompeting and displacing native species and compromising flood defences, navigation and leisure activities. Despite its relatively recent introduction, establishment and spread have been exponential thanks largely to its extremely fast growth rate (up to 20cm per day) and its ability to re-generate from small fragments. In 2010, floating pennywort was added to section 14, schedule 9 of the UK’s Wildlife and Countryside Act 1981. A recent report estimates its cost to Great Britain’s economy as £25.5 million each year through management, disposal, flooding and indirect costs to boating and angling. News that from 2014 the sale of this plant will be banned is significant and welcomed.
CABI welcomes action that the EU has recently taken (September 9, 2013) to protect member states against the adverse impacts of Invasive Alien Species (IAS). The draft Regulation on the prevention and management of the introduction and spread of IAS will help to coordinate management and preventative measures across the whole of the EU, leading to what will effectively be a joint battle against IAS – a problem that costs the EU at least 12 billion Euros each year.
CABI’s initial views on four key areas are summarised below:
A list of invasive alien species of Union concern
Identifying invasive species of European concern is at the core of this Regulation and we are pleased to see that lists of these species will be compiled based on scientific evidence. However, impact evidence, in the form of scientifically replicated studies, is currently lacking for many IAS across the EU. The lack of such data will inevitably have an impact on the strength of risk assessments for individual species.
Inclusion of chapter IV – Management of IAS that are widely spread
CABI is pleased to see that the draft Regulation highlights the valuable work that has been and continues to be conducted throughout EU member states, and welcomes the consultations to the draft Regulation, including all the steps needed to implement it. The inclusion of chapter IV – Management of IAS that are widely spread – is particularly welcomed, as these species are often overlooked due to the networks, resources and time needed to address them on an EU-wide scale.
Inclusion of all management methods, including biocontrol
CABI also welcomes the inclusion of all management methods into the Regulation (physical, chemical and biological actions), as the control and management of some of the more widespread EU weed species can only realistically be achieved using integrated pest management options, in particular classical biological control. Biological control also plays play an important role in protecting aquatic and riparian habitats, and so helps meet requirements of the EU Water Framework Directive as chemical and mechanical control options are often impractical or prohibitively expensive or taboo in such cases.
Inclusion of habitat restoration post control
It is encouraging to see the inclusion of habitat restoration post control, though it will be difficult to implement from a practical point of view due to cost and the highly disturbed nature of many of the habitats invaded by IAS.
Dr Dick Shaw, CABI’s Global Director of Invasive Species Management says:
“It’s great to see this initiative come so far and that Member States may soon have to do something about invasive species that can and do wreak havoc to biodiversity and their environments. There will be a lot of horse trading to come but I believe the will is there to make a change in the face of such a major and cross-cutting threat.”
The state of Queensland has got an alien thorny invader: Prickly acacia, or in scientific terms Acacia nilotica subspecies nilotica.
Prickly acacia is a shrub or small tree which belongs to the plant family Leguminosae, subfamily Mimosoideae, a family which also accommodates the sensitive plant Mimosa pudica, well-known as a curiosity house plant. The prickly invader A. nilotica is native to Africa, the Middle East and the Indian subcontinent and was introduced from India into Australia in the late 1890s. Originally imported as an ornamental, A. nilotica ssp. indica was later widely used as a shade and fodder tree for sheep. But what was initially a valued addition to the Australian flora soon became a menace. When the grazing regime in Australia changed from predominantly sheep to cows and the country also experienced a number of successive wet years, the balance swung in the favour of prickly acacia. The thorny shrub spread quickly and has now invaded around six million hectares of arid and semi-arid land in the State of Queensland. Acacia nilotica ssp. indica is also present in the Northern Territory as well as in Western Australia. Due to its substantial impact on the environment as well as on the economy, particularly on the livestock industry, prickly acacia was initially declared a noxious weed in Queensland in 1957. Subsequently the plant has also been listed as a “Weed of National Significance” for the whole of Australia. And Australians have every reason to be worried, as the prickly invader has got the potential to spread throughout the arid regions of the whole of northern Australia.
A well-balanced article about the biological control of Japanese knotweed was published today in a British newspaper. Most articles about the release of the Japanese knotweed psyllid (Aphalara itadori, pictured) that appeared last year were either dismissive of the idea of releasing a non-native insect to combat another non-native species, often on the grounds that the selected agents will also damage native species. Or the articles just copied bits of press statements.