Asian hornet


Could a single insect change history? A queen hornet from the Vespa velutina species could make that claim.

Also known as the Asian hornet, it hitched a ride to the port of Bordeaux in a shipment of Chinese pottery. After arriving in southwest France, this single hornet, already mated with multiple males, embarked on a journey that would have significant ecological repercussions. She built a nest, and from this one nest, up to 500 new queens could have emerged.

For a few years, the Asian hornet population quietly flourished. By the time authorities recognised the threat posed by this predatory yellow-legged hornet, it was too late. Over two decades, France became home to an estimated 500,000 nests. The Asian hornet then spread to Spain, Portugal, Switzerland, Italy, Germany, Belgium, the Netherlands, and the United Kingdom.

The Asian hornet first appeared in Tetbury, Gloucestershire, in 2016, sparking widespread alarm. Media outlets have since characterized the hornet as a “killer” predator that devastates honeybee populations and poses potential threats to human health and livelihoods. Recent headlines have amplified these fears, such as the Express’s warning: “UK Asian hornet hotspots mapped as killer species invades Britain”.

This narrative feeds into a broader fear of invasive species, but the question remains: how destructive is this hornet, and will it become a permanent resident in Britain?

Since establishing a foothold in France, the Asian hornet found the English Channel to be a natural barrier. However, according to Ian Campbell of the British Beekeepers Association (BBKA), which represents 25,000 hobbyist beekeepers, “last year was a bit of a gamechanger.”

Between 2016 and 2021, there were only a few sightings each year, and the government’s National Bee Unit (NBU) effectively destroyed the nests and individual hornets found. In 2022, just one hornet and one nest were captured and destroyed.

In contrast, 2023 saw the destruction of 73 nests. The Asian hornet established significant strongholds along the Kent coast, where approximately 50 nests were found. Colonies were also discovered in East Sussex, Hampshire, east London, Hull, and even Newcastle.

This year, Asian hornets were first spotted in Britain in March, a month earlier than usual, indicating that some may have overwintered in the country for the first time. Genetic analysis of three hornet queens found in East Sussex showed they were offspring from a nest destroyed in Rye in November last year, suggesting local overwintering.

The rise in hornet numbers can be attributed to booming populations along the coasts of France and Belgium. Asian hornets are being inadvertently transported to the UK in lorries and holidaymakers’ cars, with some experts believing that favourable winds could allow hornets to cross the Channel on their own.

The Asian hornet is smaller than the UK’s native European hornet and larger than a queen wasp. It is distinguishable by its blacker appearance, yellow legs, and an orange face, whereas the native hornet has a more gingery hue. The Asian hornet’s abdomen is predominantly black with one thick orange band, compared to the more yellowish abdomen of the native hornet.

Both hornet species are mostly carnivorous, preying on other flying insects. However, while the European hornet has coexisted with local insect populations, the Asian hornet’s numbers are not being controlled by natural predators or pathogens in Europe. This has led to its rapid population growth.

Beekeepers are particularly concerned about the impact of Asian hornets on honeybee populations. Asian hornets have been observed hovering outside beehives, capturing worker bees as they emerge.

“A honeybee hive is like a supermarket for the hornets,” says Campbell.

A single Asian hornet can hunt and consume up to 50 bees a day. Their collective impact is substantial; hornet nests can grow to the size of a watermelon by late summer and house up to 3,000 hornets. A French study found that one Asian hornet nest consumes 11.3kg of insects each summer, with a typical honeybee weighing 116mg.

“That’s a heck of a lot of insects in an environment where we are already worried about falls in insect populations,” says Campbell. “The impact on biodiversity could be very significant.”

Besides killing honeybees, the presence of Asian hornets induces “foraging paralysis” in worker bees, causing them to hide in the hive and fail to collect enough nectar and pollen for winter survival. The exact impact of the hornets’ arrival is difficult to quantify, as many factors influence honeybee productivity.

In Portugal, some beekeepers report losing 50% of their hives due to Vespa velutina, while French beekeepers attribute 29% of honeybee colony mortality to the hornets.

The economic impact extends beyond beekeeping. In Europe, ripening fruit in vineyards and orchards has been damaged by Asian hornets, threatening wine and fruit production. Some outdoor markets in France have relocated indoors due to the hornets being attracted to fresh produce.

There are also concerns about public health. Early summer nests are often built low to the ground before colonies move higher into trees later in the season. While spring queens are not particularly aggressive, they could pose a threat if disturbed. In France, there have been reports of deaths following allergic reactions to multiple stings, but reliable data is scarce.

Some question the narrative of fear surrounding the Asian hornet. Chris Packham, writing for the Guardian, argued that other threats to biodiversity, such as pesticide use on British farmland, are more significant.

Some scare stories have confused the Asian hornet with the Asian giant hornet (Vespa mandarinia), also known as the “murder hornet,” which is unlikely to establish itself in the UK due to the colder climate.

Despite the relatively few scientific studies quantifying the Asian hornet’s impact on biodiversity and insect abundance, anecdotal evidence has been compelling.

“Ecologically, yes, it will alter things. I don’t think it’s going to be devastating,” says Seirian Sumner, a professor of behavioural ecology at UCL. “Unless you are a honeybee farmer, you probably don’t need to worry too much. I worry on behalf of the other social wasps, because they represent a significant proportion of their diet, but I’m sure I’m alone in that.

“I also worry about how it’s going to affect public perceptions of wasps and hornets. We are at a time where we need to be encouraging people to embrace every facet of nature, no matter how revolting or scary, because every part of an ecosystem has a role to play. And we are the cause of all these invasive insects.”

A study examining the hornet’s effect on the native buff-tailed bumblebee found that the hornets could capture the bees but struggled to fly off with them, as the bees would drop to the ground, pulling the hornet down. This behaviour suggests that bumblebees have evolved defences that provide some resilience against the hornets.

The UK government’s response to the hornet invasion has faced criticism, but many experts defend the efforts of the NBU and the Non-Native Species Secretariat. These organisations highlight the dangers of invasive species, such as Japanese knotweed, and have led a campaign to encourage public reporting of Asian hornet sightings to help control the population.

The government remains committed to “eradication,” but future strategies might include “containment” and accepting the Asian hornet as a permanent resident. Professor Helen Roy of the UK Centre for Ecology and Hydrology commends the efforts that have prevented the hornet’s establishment for eight years.

“Hopefully, the same will happen this year. Prevention is by far the most important way to address the threat of invasive species,” she says. “We are right to consider invasive species as one of the main five drivers of biodiversity loss. And social insects, such as Vespa velutina and ant species, are a particular concern. There is good evidence of the impact that they are having on native biodiversity.”

In 2022, 8,000 potential sightings were reported via the free app Asian Hornet Watch. In 2023, 20,000 sightings were investigated, with about 150 confirmed as genuine. The NBU’s 60 officers were then dispatched to destroy the nests.

“People still struggle with its identification – and that’s understandable, because insect ID is not straightforward – but I feel really inspired by the citizen science and people’s willingness to get involved,” says Roy. “The beekeeping community have been amazing at raising awareness as well.”

Campbell fears that this year could determine whether the government continues its eradication policy or is overwhelmed by sightings, forcing a shift to containment.

“There were tensions last year when the speed and scale of responses didn’t always match the threat level,” he says. “We know the NBU is a small unit and we know this is a once-in-a-lifetime opportunity to stop the hornets establishing. Once they are established, it will be nigh on impossible to get them out.”

Technological advancements may aid the fight against the hornet. Scientists at the University of Exeter have developed VespAI, an automated bait station that alerts operators to the presence of Asian hornets. Hornets can also be fitted with miniature radio tags to track them back to their nests for destruction. Jersey’s hornet hunters have developed a low-tech yet effective method using silver streamers attached to hornets to track them by sight and locate nests.

New Zealand, a country heavily impacted by invasive species, is pioneering innovative responses. Plagued by the common wasp (Vespula vulgaris), researchers there are exploring gene drives to produce sterile male wasps. Similar techniques could potentially be developed for the Asian hornet, though scientists caution that biological controls can have unintended consequences.

The invertebrate charity Buglife argues that preventing the arrival of harmful invasive species is crucial.

“The Asian hornet is a poster child for invasive species. We can’t let this be the first of many – it needs to be the last,” says David Smith, Buglife’s advocacy and social change officer. “Addressing those pathways means we are probably going to capture or prevent more species from arriving, rather than focusing solely on a handful of species.”

While Asian hornets primarily arrive in the UK via ships, the broader issue of importing goods, especially plants, in soil poses significant risks.

“There are some easy biosecurity steps that are being ignored,” says Smith.

The EU has banned British exports of plants in soil, but the UK continues to import plants in soil, which can harbour unknown animal life.

“How about we make it two-way and increase our biosecurity?” says Smith.

A government action plan for better biosecurity has been drafted but is still awaiting consultation and implementation. As the situation with the Asian hornet evolves, it underscores the importance of proactive measures and international cooperation in managing invasive species and protecting biodiversity.

“There is a lack of attention, lack of focus and a lack of bringing [animal biosecurity] up to the standards of plant health,” says Smith. “It’s not an experiment we can afford to do. We can’t let the Asian hornet be this moment in time where we go: ‘It’s here now, we’ll deal with the next one when it arrives.’ It should be a real warning that others are waiting in the wings, particularly with the climate crisis.”



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