Revealed: The invasive species devastating Britain, including Asian hornets, giant hogweed and deadly shrimp

By William On Sep 4, 2023

Britain is home to 2,000 invasive species, including the gray squirrel, which threaten our native wildlife, experts warn.

A major report, published today, reveals the extent to which “alien” species have spread across the planet, wreaking havoc on wildlife and even human health.

Thousands of these plants, animals and other organisms can be found in Britain, having been introduced by human activity.

These include gray squirrels, Asian hornets and rhododendrons, which can be devastating to our native species.

The report, which is the first global analysis of invasive alien species and their management, is produced by the Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services (IPBES).

Britain is home to 2,000 invasive species, including the gray squirrel, which threaten our native wildlife, experts warn. In the photo: giant hogweed

This shows that there are more than 37,000 alien species introduced by human activities to regions around the world, with a global economic cost of £336 billion in 2019.

Of these, 3,500 are ‘invasive’, with known negative consequences for nature and humans.

More than 200 new alien species are recorded each year, and these have been a major factor in 60 percent of global animal and plant extinctions.

Professor Helen Roy, an ecologist at the UK Center for Ecology and Hydrology and co-chair of the report, said one of the best-known biological invasions in Britain is that of the gray squirrel.

They were first introduced to England from North America in 1876 as an ornamental species to populate the grounds of stately homes.

It wasn’t until 1930 that the damage caused by the species was recognized: They compete with our native red squirrels for food and habitat and carry a deadly virus that can kill red squirrel populations.

They are also devastating to British timber, costing the industry around £14 million a year.

“But there are other examples as well,” Professor Roy said. ‘Minks in Britain are causing problems for native water mice and driving their numbers to very low levels.

‘The rhododendron, which is so prolific in the understory of many UK forests, is definitely a reservoir for fungal tree diseases.

Professor Helen Roy, an ecologist at the UK Center for Ecology and Hydrology and co-chair of the report, said one of the best-known biological invasions in Britain is that of the gray squirrel.

There have been increasing sightings of the Asian hornet in recent years, raising concerns that it is an important predator for our native bees

Britain’s most invasive species

Gray squirrel: Outcompete our native red squirrels for territory and food, carrying a deadly virus that can kill red squirrel populations. Cause great damage to beech, sycamore, oak, poplar and birch.
Asian hornet: An invasive species from Asia, first reported in the UK in 2016. They pose a significant threat to our native bee colonies and sightings are increasing.
Harlequin ladybugs: A highly invasive non-native species that has spread rapidly across Britain since their arrival in 2004. They are described as the fastest invading species in Britain and prey on native ladybirds.
Killer shrimp: First discovered in Britain in 2010 and considered one of the most damaging invasive species in Europe. They prey on a range of native animals, fish eggs and even young fish.
Oak processionary caterpillar: First introduced in England in 2005 and pose a health hazard to humans and animals. Their caterpillars can devastate oak trees, and their tiny hairs can cause skin rashes, eye irritations, sore throats, and breathing difficulties in humans and animals.
Mink: Originally from North America, but now found all over Britain. They eat a wide variety of mammals, birds and fish and competition has driven the native water mice down to a low number.
Signal crayfish: Introduced in British waters in the 1970s. They outnumber native white-claw crayfish for habitat and food, feeding on a variety of fish, frogs, and invertebrates.
Giant hogweed: Originates from southwest Asia and was first reported in Great Britain in 1828. The disease is now common in much of Britain and can cause blisters on human skin.
Rhododendron: Although loved by gardeners, rhododendron is another invasive alien species in Britain, native to the Himalayas. It harbors a fungus that kills other plant life and in Scotland is rapidly displacing many other species.

‘Killer shrimp also cause a lot of problems in our freshwater systems.’

In recent years there have been increasing sightings of the Asian hornet, raising concerns that it is an important predator for our native bees.

Experts are also concerned about the harlequin ladybug, an aggressive predator with a huge appetite that could threaten our native ladybugs by outcompeting them for food.

Giant hogweed, on the other hand, is an alien species that can affect human health, sometimes causing unpleasant blisters on the skin of people who come into contact with it.

Of Britain’s 2,000 non-native species, 12 to 14 per cent are known to cause problems for biodiversity and ecosystems, Professor Roy added.

The oak processionary caterpillar, accidentally introduced to imported trees in London in 2006, can have devastating effects on oak trees.

They also release a toxic protein that causes rashes, irritation and breathing difficulties in animals and humans.

Experts are also concerned that some alien species not currently found in Britain could arrive soon, such as raccoons.

The IPBES report describes invasive alien species as one of the top five drivers of the ‘biodiversity apocalypse’, linked to climate change and pollution.

Commenting on the report, Dr. James Bell, Quantitative Ecologist at Rothamsted Research said: ‘This report represents an important milestone and provides much-needed evidence on how humans and nature are under extreme pressure from more than 3,500 invasive alien species around the world.

‘Professor Helen Roy is a world leader in monitoring invasive alien species and her team provides the scientific basis to support the UK’s policy response and species alerts.’

‘Early detection and monitoring of these invasive species is key to success, yet we are still very vulnerable.

‘Effective control is often absent or too complicated, which is why prevention is better than cure.

‘Take for example the Box Tree Moth caterpillar which has spread rapidly from East Asia across continental Europe and is now systematically defoliating native boxwood plants in southern England, not to mention our beloved garden boxwood plants – we can only watch.

“The UK is not keeping pace with the rapid increase in invasive alien species and effective, coordinated control at national level is imperative.

Experts are also concerned about harlequin ladybugs, an aggressive predator with a huge appetite that could threaten our native ladybugs by outcompeting them for food.

“Significant new investment in monitoring infrastructure and control measures is needed to help conservation organizations identify and then mitigate growing threats.

Several recent invasions of Britain should cause us concern for the near future and beyond.

“This includes the impact of the Asian hornet on our honeybees, the devastating effects of the rapidly spreading Himalayan balsam on our precious wildlife reserves, and the growth of ‘crayfish plague’, a disease spread by the invasive American signal crayfish. to exterminate our native crayfish.’

HOW INVASIVE GRAY SQUIRREL CAN KILL RED SQUIRREL

Red squirrels are native to Britain and spend most of their time in the trees.

However, gray squirrels were introduced to Britain from North America in the late 19th century.

Initially introduced as an ornamental species, they soon spread throughout the United Kingdom and other European countries, such as Italy.

Gray squirrels carry a disease called squirrel parapoxvirus, which doesn’t seem to affect their health, but often kills red squirrels.

Gray squirrels are more likely to eat green acorns, and so will decimate the food source before the red squirrels get to them.

Red acorns cannot digest mature acorns, so they can only eat green acorns.

When red squirrels are pressured, they will not breed as often, which has compounded the gray squirrel’s initial problem.

Another big factor in their decline is the loss of forest over the past century, but road traffic and predators are all threats as well.

It is currently estimated that there are only 15,000 red squirrels left in Britain.