Blog – bees, beekeeping & other sticky subjects
Secrets of Asian hornets’ nests
If you think it’s easy to spot an Asian hornet nest, think again!
At Apinov (Vita’s partner in France) in La Rochelle, Dr Benjamin Poirot has a wealth of experience in dealing with Asian hornets, so you might expect that a nearby nest would give obvious visual clues. Not so!
An Asian hornet nest very near his office went undetected until the leaves fell in autumn.
How can the hornets keep their huge nests so secret?
They give very few visual clues indicating the whereabouts of their home. You might expect Vespa velutina to fly straight back to its nest with it its prey. It doesn’t. It flies to a nearby perch — any direction — to behead up its catch.
So, watching Vespa velutina after it has caught a snack won’t help much. You might expect to see a lot of traffic to and from the nest — there isn’t.
However a new tagging system is emerging that may be able to track its whole flight path.
And to catch Asian hornets predating your bees in late summer, there’s Apishield.
Asian hornet – the lost opportunity
At the 2018 International Meeting of Young Beekeepers last week, adults in the group had the honour of meeting the man who first discovered the Asian hornet (Vespa velutina) in France and learning o an early missed opportunity.
Dr Jean Haxaire, associate professor at the University of Agen, discovered an Asian hornet quite by chance in some fruit near Bordeaux in 2004. Immediately realising that this could be significant, he identified the strange insect as Vespa velutina and alarm bells in his head started ringing. He knew of the reputation of hornets in the Far East and therefore realised that this could be a serious threat to France.
Dr Haxaire rapidly published an article in a scientific journal, but was very disappointed that reaction was muted and no-one seemed to want to take action. Sadly, his worst fears were to be realised as the hornet became established and within a couple of years its spread throughout France and beyond became unstoppable. If action had been earlier, there might have been some hope in preventing its spread, but now he says we must regard it as a native of France – even though it is an uninvited guest.
Dr Haxaire is now certain that, as first thought, the intruder came in a consignment of bonsai plants. Genetics and trading patterns indicate with some certainty that it came into Bordeaux via Shanghai.
The good news might be that at least velutina wasn’t one of its Far Eastern relatives that can be many times its size! The bad news is that it is an amazingly adaptable insect.
With graphs showing how the demographics of a nest changes through the season, Haxaire emphasised the importance of destroying nests early in the autumn before foundress queens emerge. When they do appear, the problems of further spread become enormous. In France, the trigger date for the first emergence of the queens is usually around the end of September.
The extent to which velutina predates on bees is strongly correlated with the environment – in cities, the predation is greatest because there are relatively fewer dietary alternatives to honey bees.
Attending the IMYB event a few days later, Dr Benjamin Poirot a honey bee specialist from Apinov in La Rochelle said that the situation in France this year at the beginning of July is very serious. He says he has never seen so many Asian hornets so early in the year. And he should know – for the past several years he has frequently been called out to destroy nests when they are found.
Varroa Hotspots Mystery
Hotspots of varroa resistant to many treatments have developed over years of use and mis-use. While the basic principles of resistance to treatments are understood, the details remain a mystery as bees and beekeepers face an adaptable pest.
In France, Gabrielle Almecija, a PhD student at the University of Tours, has recently begun a three-year research project about resistant varroa. Part-sponsored by Vita Bee Health and Apinov (Vita’s partner in France), Gabrielle is already studying varroa in Brittany where resistance to some treatments seems low, and varroa in the Alps where resistance seems high. Why there should be such a difference is far from clear, but it is typical that there is considerable variation between geographical areas.
As the first stage of her research, Gabriele will be lab-testing varroa mites to define levels of resistance: how much of a treatment is required to kill a certain proportion of mites? At the moment, she must travel to and from each area, but plans to establish a protocol, a reliable scientific method, by which the time-consuming travel will not be required.
Once resistance levels can be defined, possibilities for further research and practical action open up. Just four months into the research, Gabrielle’s work is showing great potential.
This honey bee-related project is not Gabrielle’s first encounter with bees. Previously she has studied and has given presentations on urban forage in her home area of Marseilles and has studied brood disease and queen breeding. It was in La Rochelle that she first met Benjamin Poirot of Apinov who is helping to supervise her PhD.
Here’s a gruesome glimpse at what she is finding:
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Singing queen silencedThe observation hive is back in action and the queen has been singing — quarking, if you prefer — but then she abruptly stopped.
A frame with a sealed queen cell had been installed in the observation hive and a queen quickly emerged. Running around the hive she was buffeted by the workers and returned the compliment clambering on some of them, feelers flying. (Workers are impatient with virgin queens and urge them to go and get mated!) Mostly the queen tried to stay outside the loose cluster to have some peace and quiet.
She was quarking frequently and then I saw the reason — another sealed queen cell. After about a day, the workers unceremoniously tore down that second queen cell and removed the developing white larva. Not following the text books, they didn’t tear it down at the side, but instead attacked it from the bottom dragging out the larva.
After one more triumphant quark (apologies for the anthropomorphism), the queen became silent and work in the office could continue uninterrupted.
The behaviour of the workers to the queen has become much more deferential over the past day or two, so I expect that she has mated and may even be laying eggs, but they aren’t yet visible.
Vita’s Guest Beekeeper Blogger