Page 42 - ALG Issue 2 2018 html
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 Expert guide to...
 Figure 1: Keep an eye out for the Asian hornet. Note the characteristic yellow legs and the yellow band on the 4th segment of the abdomen
Do you know your Asians from your Europeans?
Hornets that is! The concerns about Asian hornets explained.
'This article was prompted by the British Beekeepers’ Association, but written by the following members from the National Bee Unit: Mike Brown, Nigel Semmence and Jason Learner.
The yellow-legged Asian hornet, Vespa velutina, also known simply as the Asian hornet, is an invasive species from Asia and first arrived in Europe in 2004, where it was reported in Lot-et-Garonne, in the south west of France. It is believed to have hitch hiked a ride in a pottery consignment from China.
As adult hornets are highly mobile, it has since spread across almost all of France, at a rate of approximately 60 km/year. At the time of writing, it has spread into Spain, including the Island of Majorca, Portugal, Italy, Belgium, Germany, Switzerland,
the Channel Islands and the UK. Asian hornets are principally predators of insects, particularly pollinating insects, including honey bees. The fear is that hornet populations will have potentially serious consequences and impact on insect diversity in countries where it is now established.
In such places, it could significantly reduce the country’s diversity of pollinators because they are an easy and abundant source of food. The hornet’s impact has been particularly disastrous on honey bee populations in France, where it has now been established for over thirteen years, reducing honey yields and furthering honey bee colony losses in certain parts of the country.
In September 2016 the Asian hornet was discovered for the first time in the UK near Tetbury, Gloucestershire. Hornets were detected by a vigilant beekeeper who had seen hornets hawking and hunting in front of his bee hives. The beekeeper immediately contacted the APHA National Bee Unit Bee Inspectors to confirm his suspicions. Once the hornet had been quickly confirmed,
the contingency plan was set in motion to search for the nests and hornets and which intensified in the west of the country. The nest was detected, destroyed and removed from the area. No further positive sightings of hornets have since been reported in the Tetbury area.
Importantly during these searches, further hornet samples were reported, including a sample from the Bath area. It turns out that this particular sample had been brought back in a vehicle from a camping trip to the Loire Valley in France. Thankfully, this hornet was not connected to any established population in Bath.
Moving to September 2017 another vigilant beekeeper in Devon once again reported to the National Bee Unit Asian hornets hawking and hunting in his apiary. Our contingency plan was again activated and a nest discovered and destroyed in Woolacombe, Devon. Since then, once again no other Asian hornets have been seen in the area.
The Stakes Are High
The above examples indicate that we need to be particularly careful not to bring back queen Asian hornets which are able to
reproduce and make further queens later
in the year (See Figure 5 for more details). The likelihood of doing this increases in
the spring, from February to April because over wintered queens will emerge from
their hiding places, even on rainy, warmish days, looking for sites to set up a very small primary nest. This nest will grow to around 20-30 individuals and then the population will begin the establishment of a larger secondary nest if there is room; if not they may relocate nearby.
During her time building the primary nest, the queen will be quite vulnerable and so could choose somewhere sheltered. The risk increases towards the end of autumn,
in October and November when nests produce the new queens for the next generation. These queens will then look for a sheltered spot to overwinter and this could be somewhere on your allotment. These overwintered queens will then emerge the following spring to set up a new nest and each new nest can produce hundreds of new queens for the following year!
You may actually see Asian hornets flying or foraging. In the next part of the article we describe how to identify and distinguish the Asian hornet from our native one.
What is that coming over the hill?
The Asian hornet can be distinguished easily from our native hornet so it is important to learn the differences between the two.
The first obvious differential feature is the abdominal colouration. The Asian hornet
is mostly black with a yellow/orange band towards the end of the body (Figure 1 and
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