Asian Hornets...

[fian]

Are we to assume that with so many sightings and quite a distance between the confirmed nests that they've finally started to get a foothold on the UK mainland?

What are the predictions on timescales for their eventual spread across England, Wales and possibly lower parts of Scotland, only the Highlands being too cold For them?

In Galicia the average propagation was 50 km/year in areas with a gentle slope and without physical altitude barriers (mountains over 800 m).

 

[pargyle]

Where I am ... halfway between Portsmouth and Southampton abs with Farehams mild climate its not a case of if they arrive.. more a case of when. I see the occasional European hornet in the garden...beautiful creatures that they are .. and every time I see one its a double take ! The advice we have is not to trap but to be vigilant and get photo if one is sighted. They were very quick to react in Gosport last year.

 

[Erichalfbee]

Where I am ... halfway between Portsmouth and Southampton abs with Farehams mild climate its not a case of if they arrive.. more a case of when. I see the occasional European hornet in the garden...beautiful creatures that they are .. and every time I see one its a double take ! The advice we have is not to trap but to be vigilant and get photo if one is sighted. They were very quick to react in Gosport last year.

You’re seeing them in your garden?

 

[The Poot]

You’re seeing them in your garden?

European hornets…..

 

[Erichalfbee]

European hornets…..

Sorry. Wake up Dani!

 

[pargyle]

You’re seeing them in your garden?

You’re seeing them in your garden?

Not yet, but we are pretty much in the front line here so I keep my eyes open - it's only a matter of time I fear and as the climate here is several degrees above the UK average they could potentially overwinter here.

 

[fian]

Asian hornet queens winter underground. When the temperatures begin to rise, they come out of their lethargy and found the primary nest. This is the time to cheat as each captured queen is a nest that ceases to exist.

 

[Erichalfbee]

I’m reading reports from some beekeepers that the NBU want more involvement from beekeepers who know their areas but DEFRA won’t let them engage. So the number of sightings it reports via the BBKA is underreported. Could the number of hornets actually declared by DEFRA be the tip of the iceberg in reality?

 

[manek]

It's certainly underreported here, where in the port town of Newhaven, just a few km down the road, several V. velutina have been spotted, captured and reported.

Not much mention of this incursion by DEFRA. Looks to me like there's a nest somewhere...

 

[OXFORDBEE]

It's certainly underreported here, where in the port town of Newhaven, just a few km down the road, several V. velutina have been spotted, captured and reported.

Not much mention of this incursion by DEFRA. Looks to me like there's a nest somewhere...

Fear not, Newhaven got a BeeBase mention today. Folkstone seems to be clocking up nests at the moment.

 

[Murox]

I’m reading reports from some beekeepers that the NBU want more involvement from beekeepers who know their areas but DEFRA won’t let them engage. So the number of sightings it reports via the BBKA is underreported. Could the number of hornets actually declared by DEFRA be the tip of the iceberg in reality?

Nothing like British bureaucracy is there!

 

[fian]

Remember that the radius of action of a velutina nest is around 5km, which means that if the distance between two sightings is greater than 10km then there is a high probability that they are different nests.
This, together with the average advance of 50 km/year, means that at least 25 nests will be established in the area of advance.
25 is a lot?
A developed secondary nest like those seen in Galicia or France can generate 2,000 queens by the end of September. It is true that queens must mate and survive the winter to found a new colony.

 

[Dodge]

Spring 24 is I immagine will be the pivotal year for Asian Hornets. If traps start getting mated queens we will know nests were missed. Depending on how wide an area queens are discovered will probably indicate if the incursion is probably long tern if not permanent.

May be using queen pheromone to trapping in Autum with queen trapping in Spring would be an interesting idea. If you miss queens trapping then it increass the chances that these queens are not fertile and if you trap drones you know nests are about.

 

[Karol]

Perhaps a little reality check might be in order.

How old a species do we think Velutina is? A few 100 thousand years, perhaps a few million years? At a rate of spread of 50km per annum why is it not already established across the whole world including the UK? Afterall Vulgaris pretty much is!

There's a reason why Crabro hasn't evolved nests of thousands of individuals in temperate climates.

We are likely to continue to see sporadic nests. That's not the same as having an established population of Velutina. Prudence dictates eradication wherever outbreaks occur but the UK is not France or Galicia and I suspect Velutina populations will have been knocked back in parts of Spain as a consequence of the arid conditions seen this summer. It is after all a forested wetland species needing vast amounts of insect prey to sustain itself.

 

[fian]

Perhaps a little reality check might be in order.

How old a species do we think Velutina is? A few 100 thousand years, perhaps a few million years? At a rate of spread of 50km per annum why is it not already established across the whole world including the UK? Afterall Vulgaris pretty much is!

There's a reason why Crabro hasn't evolved nests of thousands of individuals in temperate climates.

We are likely to continue to see sporadic nests. That's not the same as having an established population of Velutina. Prudence dictates eradication wherever outbreaks occur but the UK is not France or Galicia and I suspect Velutina populations will have been knocked back in parts of Spain as a consequence of the arid conditions seen this summer. It is after all a forested wetland species needing vast amounts of insect prey to sustain itself.

I am going to reveal something to you, here in Galicia both the wasps and the European hornets have not developed permanent nests. In fact, the velutina does not do it either, the queens hibernate in the coldest season.
Regarding the number of individuals, let's say that by lacking enemies, its population can grow up to the ecological limit. Additionally, there is a difference between a European wasp or hornet and its Asian counterpart and it turns out to be the same as in a bee hive and it is none other than the existence of 3 castes (workers, queen and drones) for velutina but in wasps and hornets Europeans there are only queens and drones.

 

[Karol]

It's important not to confuse the different genera of wasps. Doing so can be misleading and cause unintended consequences.

Polistes wasps behave very differently to Vespine wasps. We don't (as a rule) have Polistes wasps in the UK.

European (paper) wasps, aka Polistes dominula should not be confused with European hornets Vespula crabro.

Vespula crabro nests have typically 200 to 400 adults.
Vespula velutina nests in ideal ecological surroundings typically have a few thousand adults.
Vulgaris and Germanica nests similarly have several thousand adults but are much smaller insects. They are still very capable of causing considerable destruction to bee hives.
IF Velutina were to establish itself in the UK it will ameliorate to UK ecology and cause no more harm than Vulgaris or Germanica.

 

[fian]

It's important not to confuse the different genera of wasps. Doing so can be misleading and cause unintended consequences.

Polistes wasps behave very differently to Vespine wasps. We don't (as a rule) have Polistes wasps in the UK.

European (paper) wasps, aka Polistes dominula should not be confused with European hornets Vespula crabro.

Vespula crabro nests have typically 200 to 400 adults.
Vespula velutina nests in ideal ecological surroundings typically have a few thousand adults.
Vulgaris and Germanica nests similarly have several thousand adults but are much smaller insects. They are still very capable of causing considerable destruction to bee hives.
IF Velutina were to establish itself in the UK it will ameliorate to UK ecology and cause no more harm than Vulgaris or Germanica.

If you think that in this nest of about 60 cm in diameter there are only a few thousand adults, then you are greatly underestimating the velutina.
Samples of the captured velutinas have been taken and it has been confirmed that they are all daughters of the original landed in Bordeaux in 2004.

 

[Karol]

Typically a few thousand, of the order of 5 to 6000. Much the same as Vulgaris or Germanica. If ecological conditions permit then the nests can of course get much bigger.

 

[fian]

Typically a few thousand, of the order of 5 to 6000. Much the same as Vulgaris or Germanica. If ecological conditions permit then the nests can of course get much bigger.

To give you an idea of the size of the velutina invasion in Galicia (1/2 of Wales and 1/9 to 1/10 of the surface of the United Kingdom)
Nests removed in 2021: 17,857
Nests removed in 2022: 22,223
Approximately 75% are located in coastal areas with a temperate oceanic climate very similar to that of the United Kingdom. Average coast 1.4 nests per km2. Total average 0.75 nests per km2.
Note: a nest is removed by the Galician Environmental Management Service or by the Fire Service whenever there has been a localized and confirmed warning. This means that there are many nests that are not located, so the official data is underestimating the real population.

 

[Sutty]

IF Velutina were to establish itself in the UK it will ameliorate to UK ecology and cause no more harm than Vulgaris or Germanica.

That doesn't seem to be what we are hearing from France etc. Do you think there is a large reporting bias?
In what way would it "ameliorate"?
I hope you're right as it seems likely to become endemic in at least part of the UK.