The discovery last month of the Oak Processionary Moth in a public park in Dublin has put a new focus on the increasing number of alien species that are posting a threat to the environment, economy, and potentially public health in Ireland.
Known as OPM for short, it was the first finding of the pest on the island of Ireland and led to the Department of Agriculture, Food and the Marine in Dublin taking swift action.
There have been no further sightings of the species. Members of the public and the horticulture industry have been urged to remain vigilant for the pest.
It strips oak trees of their leaves, leaving them vulnerable, but also poses a health risk to humans causing rashes and breathing difficulties and should not be touched under any circumstances at any time.
The pest is a native of central and southern Europe, where predators and environmental and ecological factors usually keep its numbers in check and minimise its impact.
However, it has been expanding northwards over the past 20 years, aided by the movement of live oak trees in trade and also perhaps by a warming climate.
It is now established as far north as The Netherlands and northern Germany and has occasionally been seen in Sweden.
First accidentally discovered in West London in 2006, it measures about one inch and is so-called because it moves about in late spring and early summer in nose-to-tail processions.
The rapid spread of a large number of invasive species in the European Union threatens native plants and animals at a cost of €12bn each year, including an estimated €250m to the island of Ireland.
Plants make up 80% of the food we eat and produce 98% of the oxygen we breathe. Yet, they are under constant and increasing threat from pests and diseases. Climate change and human activities are altering ecosystems, reducing biodiversity, and creating conditions where pests can thrive.
Increasing travel and trade has tripled in volume in the last decade and can quickly spread these invasive species around the world causing great damage to the environment.
The European Commission defines invasive alien species as animals and plants that are introduced accidentally or deliberately into a natural environment where they are not normally found, with serious negative consequences for their new home.
“As invasive alien species do not respect borders, coordinated action at the European level will be more effective than individual actions at the member state level,” it says.
Former Culture, Heritage and Gaeltacht Minister Josepha Madigan told the Dáil last November that under the current legislative framework, responsibility for invasive alien species rests, in the first instance, with landowners.
She said tackling the issue is an ongoing operational matter in the 87,000 hectares of National Parks and Nature Reserves. Since 2011, the Department had invested about €1.4m to tackle rhododendron clearance in Killarney National Park alone.
In 2018, a new stream of grant funding for local authorities was piloted to support National Biodiversity Action Plan projects including those that target invasive alien species in their areas.
Last year, €500,000 was allocated to the 28 local authorities who applied. Grant funding of €700,000 is available in 2020.
While increased global movement of people and goods and climate change have led to more invasive species being introduced to Ireland, some are not new and have been here for a long time.
Rhododendron, native to Portugal and Spain, was introduced here in the 19th century as an ornamental plant.
The shade from its canopy of evergreen leaves eradicates all life beneath. It can resist frost and survive fire and provides an ongoing threat to woodlands.
Himalayan balsam, which has been in Ireland since 1839, is most invasive in damp habitats particularly along river corridors.
It out-competes native vegetation in summer and dies back in winter, exposing riverbanks to erosion. It spreads rapidly downstream in river catchments due to its prolific seed production.
Earlier this month, the new Heritage and Culture Minister Catherine Martin told Sinn Féin TD Matt Carthy in the Dáil that it became apparent in recent surveys that the grey squirrel had disappeared from parts of the midlands, linked to the re-emergence of the pine marten, a native carnivore.
Meanwhile, red squirrel has made a recovery in some of these areas and seems capable of cohabiting woodlands with the pine marten. Similar findings have since been made in Scotland.
Japanese Knotweed, another invasive plant that was introduced into Ireland as an ornamental plant, is also difficult to control, can undermine the structural integrity of roads and buildings and is proving a headache for local authorities.
A more recent invasive species is Ash Dieback, first confirmed here on a Co Leitrim plantation in 2012. It has since spread countrywide. Scientists suggest it may have been introduced to Europe from eastern Asia.
A 2016 review published in the British peer-reviewed scientificpredicted that almost all ash trees in Europe will eventually be wiped out due to the disease spreading across the continent. Supplies of the wood is also decreasing in Ireland, with around three-quarters of ash now imported from Poland and Croatia.
With growing concern about the spread of invasive species, the United Nations has declared 2020 International Year of Plant Health.
The UN described it as “a once in a lifetime opportunity to raise global awareness on how protecting plant health can help end hunger, reduce poverty, protect the environment, and boost economic development”.