Tag: Asian hornet

Tracking an invasion – a single Asian hornet sparked the ongoing spread across Europe

It is likely that all Asian hornets in Europe are descended from a single queen introduced to France in 2004.

In Europe, the Asian (or “Yellow-legged”) Hornet (Vespa velutina) is a predator of insects such as honeybees, hoverflies, and other wasps, and poses serious risks to apiculture, biodiversity and pollination services. This hornet can measure up to 4cm in length and, like all other social wasps, is capable of delivering a painful sting, although it is not aggressive by nature. Thought to have been introduced into Europe from China in 2004, the Asian Hornet has rapidly spread across the continent. While it has been thus far controlled in Britain, the hornet is well established across mainland Europe and the Channel Islands. In April 2021, the Irish National Parks and Wildlife Service confirmed that a single specimen had been found, ‘alive but dying’ in a private dwelling in Dublin, marking the first Irish record of this species.  

The Asian Hornet specimen recovered in Dublin. Image by Dr Aidan O’Hanlon

The circumstances of how the specimen arrived in the Irish capital are not known, but with the area’s extensive regional, national and international connectivity, there can be many possible pathways of introduction. In an Irish context, it was of particular interest to determine whether this individual originated in Europe/Britain or represented a potential new invasion source from within its native range in Southeast Asia.

The specimen was deposited in the National Museum of Ireland and identified by Dr. Aidan O’Hanlon, who suggested performing genetic analysis to determine its provenance. In collaboration with scientists from the School of Biological, Earth and Environmental Sciences (BEES), University College Cork, and partners on the EU Atlantic Positive Project (which aims to establish Europe-wide methodologies for the control of the Asian hornet), genetic analysis was performed and data were compared with those from specimens provided from several other locations across Europe. The researchers then published their findings in Journal of Hymenoptera Research.

An Irish hornet. Image by Danel Solabarrieta, licensed under CC BY-SA 2.0.

“Earlier work had demonstrated that Asian hornets in Europe apparently shared the same genetic lineage, based on studies of a single gene. We took this a step further and looked at two additional genes which would be more sensitive in detecting variation within the invasive population”, explains Dr. Eileen Dillane of BEES.

Data from all three genetic markers confirmed that not only are Asian hornets in Europe of a single pedigree, but are likely descended from a single mated queen hornet that somehow arrived in France in 2004.  Furthermore, this lineage has not yet been described within the native range. 

“Our research has revealed the remarkable potential for population expansion of eusocial insects in invaded areas, even when original genetic diversity is extremely low”, says Dr. Simon Harrison, who is part of the research team .

Female V. velutina specimen from Dublin, Ireland.

These findings are both bad news and good news for the control of the Asian hornet in Europe. Whilst single mated queens can evidently rapidly re-colonise areas from where hornets have been eradicated (for example, where intensive efforts have destroyed all nests in an area), the close relatedness of all individuals of the Asian hornet in Europe offers hope for eradication methods based on biological control. 

In the Irish context, it is unlikely that this is the beginning of a larger-scale invasion, as the climate and habitat landscape of Ireland is likely less than ideal for the Asian hornet, which requires higher summer temperatures and a greater supply of energy-rich food. “Nonetheless, climate change is likely to increase the threat of a successful invasion in the future, so vigilance against this species must be maintained”, the authors of the study advise.

Original source:

Dillane E, Hayden R, O’Hanlon A, Butler F, Harrison S (2022) The first recorded occurrence of the Asian hornet (Vespa velutina) in Ireland, genetic evidence for a continued single invasion across Europe. Journal of Hymenoptera Research 93: 131-138. https://doi.org/10.3897/jhr.93.91209

What is the Asian hornet invasion going to cost Europe?

Since its accidental introduction in 2003 in France, the yellow-legged Asian hornet Vespa velutina nigrithorax is rapidly spreading through Europe. In a new paper, published in the open-access journal Neobiota, French scientists try to estimate the costs of the invasion regarding the potential damage to apiculture and pollination services.

Since its accidental introduction in 2003 in France, the yellow-legged Asian hornet (Vespa velutina nigrithorax) is rapidly spreading through Europe. Both experts and citizen scientists keep on identifying the new invader spreading all over the Old Continent in the last decades. 

In a recent study, French scientists led by Prof. Franck Courchamp at the Université Paris-Saclay and the CNRS, tried to evaluate the first estimated control costs for this invasion. Supported by the INVACOST project, their findings are published in the open-access journal Neobiota.

Since its invasion to France in 2004 when it was accidentally introduced from China, the Asian hornet has been spreading rapidly, colonising most of France at an approximate rate of 60-80 km per year, and also invading other European countries: Spain in 2010, Portugal and Belgium in 2011, Italy in 2012, Germany in 2014 and the UK in 2016. In the recent paper, published in the open-access journal Evolutionary Systematics, Dr. Martin Hussemann from CeNaK, University of Hamburg has recorded the northernmost capture of the Asian hornet in Hamburg in September 2019.

These data show that the Asian hornet is spreading all around Europe faster and faster with every year, even in climatically less favourable regions. The rapid invasion of the species is not necessarily caused by human-mediated dispersal, the species can rapidly spread on its own, but nevertheless, it is not uncommon.

Within its native and invasive range, V. velutina nigrithorax actively preys on honeybees, thus, causing harm to apiculture. Due to its active praying on wild insects, the Asian hornet also has a negative impact on ecosystems in general and contributes to the global decline of pollination services and honey production. Furthermore, by nesting in urban areas, the Asian hornet, which is well known for its aggressive behaviour, is a potential threat to human activities.

Currently, the control of the invasion is mainly undertaken by nest destruction and bait trapping, but none of these methods is sufficient enough to achieve complete eradication.

To proceed with the further control of the invasion, there is the need to evaluate economic costs. Those costs are divided into 3 main categories: (1) prevention of the invasion, (2) fighting the invasion and (3) damage caused by the invasion.

The cost of fighting the invasion of the Asian hornet is the cost of nest destruction. To identify those costs, the research team has studied information about the companies providing the services in the nest destruction, extrapolated the cost of nest destruction spatially and modelled the potential distribution of the invasive.


Estimated yearly cost of nest destruction if climatically suitable areas are fully invaded. Grey bars represent countries invasion hasn’t reached yet.
Credit: Prof. Franck Courchamp
License: CC-BY 4.0

As the calculations show, at the moment, the estimated yearly costs for eradication would be €11.9M for France, €9.0M for Italy and €8.6M for the United Kingdom.

“In 2006, only two years after the hornet was first observed in France, three departments were already invaded and the cost of nest destruction was estimated at €408k. Since then, the estimated yearly costs have been increasing by ~€450k each year, as the hornet keeps spreading and invades new departments. Overall, we estimated €23M as the cost of nest destruction between 2006 and 2015. If this temporal trend can be extrapolated for the next few years (i.e. if the hornet keeps spreading at a similar rate), we expect the yearly cost of nest destruction to reach an estimated value of €11.9M (given all suitable areas are invaded) in just 12 years,”

shares Prof. Franck Courchamp.

In Japan and South Korea, where the species has already been observed, the total yearly cost of nest destruction is estimated at €19.5M and €11.9M respectively.

So far, nests eradication is the most effective way to fight the invasion, though, it is not sufficient enough. As a result, so far, only 30-40% of the detected nests are destroyed each year in France. Moreover, rather than the result of a controlled strategy, those destroyed nests are only the ones that have been determined of particular potential harm to human or beekeeping activities. The researchers point out that this is not enough.


Estimated yearly cost of nest destruction in France since the start of the invasion given the yearly invasive range.
Credit: Prof. Franck Courchamp
License: CC-BY 4.0

In conclusion, the scientists call for more active measures and research, related to the invasion of V. velutina nigrithorax. Provided that other countries, including the USA, Australia, Turkey and Argentina appear to be climatically suitable for the species, they are also in danger (e.g., €26.9M for the USA).

The current study presents only the first estimates of the economic costs resulting from the Asian hornet, but definitely more actions need to be taken in order to handle harmful invasive species – one of the greatest threats to biodiversity and ecosystem functioning.

Consensus climate suitability of the yellow-legged hornet predicted from species distribution modelling.
Credit: Prof. Franck Courchamp
License: CC-BY 4.0

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Original source:

Barbet-Massin M, Salles J-M, Courchamp F (2020) The economic cost of control of the invasive yellow-legged Asian hornet. NeoBiota 55: 11-25. https://doi.org/10.3897/neobiota.55.38550