The spread of the invasive alien pest Asian hornet across England spells trouble for bees and beekeepers, but there could be a positive side for arborists.

ANOTHER alien pest with a ‘sting in the tale’ may already be established in England, although UK plant health authorities are predictably disputing the claim. Asian hornet (Vespa velutina), first spotted in Europe in 2004 after accidental transportation from Asia, inevitably turned up on our shores, with the first sighting in 2016. Thirteen Asian hornet nests were subsequently recorded between 2016 and 2022, but 2023 saw a huge increase, with 53 nests recorded up until the end of October. 

This has led bumblebee conservation expert Dave Goulson, a professor of biology at the University of Sussex, to express fears that Asian hornets are already established in Kent. He told the press: “It is a bit too early to say for sure, but the situation looks ominous, with a record number of nests found and destroyed this year so far [in Kent]. Even if one nest evades detection and reproduces it will then probably become impossible to prevent them establishing.”

Once established, Asian hornets will remain in the UK for good. Julie Coleman, a trustee of the British Beekeepers Association who lives in Kent, believes Asian hornets could have already overwintered in the area.

Matt Shardlow, chief executive of the insect charity Buglife highlighted the surge in Asian hornet nests found during late summer 2023. Talking to The Guardian in early September he said: “With four new Asian hornet nests found in the last week and a strong cluster in coastal Kent, it seems likely that the species has colonised England.” The Asian hornet is a risk to biodiversity and in particular can hunt and prey on large numbers of wild solitary bees.

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Shardlow said it is too early to give up on control efforts: “Removing nests has probably managed to slow its colonisation but the abundance of wasp species in general can be strongly influenced by the weather. So we can still hope that eradication efforts, perhaps with some lucky weather, might nip this colonisation in the bud.”

DEFRA was having none of this, with chief plant health officer Nicola Spence commenting: “Evidence from previous years suggested that all 13 Asian hornet nests found in the UK (2016–2022) were separate incursions.” She added that there is nothing to suggest Asian hornets are established in the UK. “We have not seen any evidence which demonstrates that Asian hornets discovered in Kent this year were produced by queens that overwintered [in England].” That said, until evidence is presented either way, the status of Asian hornets in the UK is pure speculation.

Forestry Journal: An Asian hornet nest in a tree.An Asian hornet nest in a tree. (Image: Getty)

So what are the locations of the sightings and nests found between 2016 and 2022 and which makes DEFRA confident they all resulted from separate incursions? The first record of Asian hornets in the UK was in the Tetbury area of Gloucestershire, closely followed by sightings in Devon (2017) and Hampshire and Cornwall in 2018.

Other insect pest sightings/nest findings in Berkshire (2021) and Essex and Suffolk (2022) are among the recorded sightings between 2016 and 2022. They were clearly widely spread and presumably part of the reason why DEFRA says they all resulted from separate incursions. The first insect pest sighting/nest location recorded for Kent was in 2019, with a four-year gap before the upsurge in 2023. The Folkestone area of Kent is now the Asian hornet hotspot in England. The pest has also been found in East Sussex.

This is all very interesting, especially in relation to how all these separate incursions, as claimed by DEFRA, are getting into the country. Asian hornets first arrived in Europe from Asia, stowed away on cargo, which is one avenue suggested for entry into the UK. The alternative theory is insects being blown across the English Channel or flying in under their own steam. Of course, UK plant health authorities have a vested interest in Asian hornets being blown across or flying across the English Channel, just as they have previously pushed this avenue of entry for Ips typographus.

However, evidence does not wholeheartedly support this theory. If correct, you would expect the very first insect incursions to have travelled along the shortest possible route – Pas de Calais and into Kent. However, UK sightings in the period 2016–2018 were much further away and/or well inland. The first reports were from Gloucestershire, Cornwall, Devon and Hampshire. The first Kent Asian hornet sighting/nest finding did not happen until 2019. All this leads many observers to think than Asian hornets are arriving on ships, aeroplanes and their cargoes.

Forestry Journal: Although the species is not aggressive there have been reports of people hospitalised after suffering anaphylactic shock.Although the species is not aggressive there have been reports of people hospitalised after suffering anaphylactic shock. (Image: Stock)

Several recent observations lend credence to arrivals and incursions via shipping and trade with an Asian hornet identified and photographed by a passenger on board the MS Barfleur ferry while it was docked at Poole in Dorset ahead of a sea-crossing to Cherbourg in France. In April 2023, an Asian hornet was identified on a delivery of vegetables (cauliflower) in the Newcastle area of Northumberland, and was highly unlikely to have made it across the North Sea under its own steam. The cauliflower had been imported from France.

Others point to the perverse post-Brexit situation regarding export/import of soil in container-grown (potted) plants between EU and UK. The EU has banned the import of soil in pot plants from the UK partly because a number of quarantine pests and pathogens including Asian hornet can travel undetected in soil. However, the UK has not put the same reciprocal ban in place which means we are wide open to invasion by pests and pathogens via this mode of movement.

The establishment and permanent presence of Asian hornets in UK would spell disaster for native wild bees in general and hives of honey bees. Asian hornets sit outside the hives to capture the bees as they go in and out. They subsequently dismember their prey (chopping off the head and stripping wings and legs) before feeding the thoraxes to their larvae. 

Beekeeper Simon Spratley in Folkestone, Kent, is counting the costs to his bees, with 10 of 17 hives lost in quick succession. He told the press: “These insects are going to settle here and they’re going to predate on all insects especially the honey bee – that’s their natural food source.

“They’ll end up destroying or overcomplicating beekeeping for everybody and reducing the [bio] diversity in the Kent area and the whole of wider England.”

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So what’s all this got to do with arb? Potentially a lot, because Asian hornet nests are built in trees, tucked away in holes, cavities and on broken branches but also free hanging from smaller branches. And someone has got to climb the trees to remove and destroy the nests, albeit in ‘full’ protective gear.

Forestry Journal: Other alien invasive insect pests like oak processionary moth have generated a lot of work for the arb industry and the same may happen with Asian hornet. Other alien invasive insect pests like oak processionary moth have generated a lot of work for the arb industry and the same may happen with Asian hornet. (Image: eA)

Just as oak processionary moth and Chalara ash dieback have generated huge volumes of work for the industry, so could the Asian hornet (heaven forbid) should it colonise the country.

And there could be more waiting in the wings. The Oriental hornet (Vespa orientalis) originates in Africa and South East Asia but has recently invaded Italy, and the Asian giant hornet (Vespa mandarinia), nicknamed the ‘murder hornet’, also native to Asia but with recent sightings in North America. Like the Asian hornet they can deliver a massively painful, debilitating and in certain circumstances fatal sting to humans.