BBC News, South East
Tiny tracking devices, weighing less than 160mg, are being hailed a “game-changer” in the fight against the invasive Asian hornet.
The National Bee Unit has begun trialling this ground-breaking technology, fitting transmitters to hornets in a bid to help find their nests.
Fifty-three Asian hornet nests have been discovered so far this year, the vast majority in the south-east of England. It’s a record number for this time in the season.
Genetic tests on hornets discovered in Kent and Sussex have revealed for the first time that second-generation hornets are being produced in Great Britain.
Yellow-legged Asian hornets are seen as a significant threat to honey bees and other pollinators.
One nest of hornets can eat up to 11kg (1.7 stone) of insects in a single season.
Tracy Wilson, from the Animal & Plant Health Agency (APHA), called the new trackers “game-changers” in their work and said the speed at which nests could now be found would mean resources were freed up to find more nests.
Dan Etheridge, from the National Bee Unit, has been experimenting with the transmitters in the UK over the past week.
“We’ve already used six tags and we’ve found six nests, so it’s going to speed things up dramatically for what we do in the field,” he said.
Hornet nests can be very high up and hard to spot. One of the nests found using the trackers was in dense woodland.
Finding a nest in this environment using traditional tracking methods, timing a hornet’s return to a bait stations and looking at flight lines, can take hours if not days.
But Mr Etheridge said by using the transmitters the nest was found “in no time at all”.
“We were able to go under the nest and point the receivers around a few trees… and then we slowly narrowed it down,” he said.
Fitting the tracker is delicate work. A female worker hornet is captured from a bait station and weighed to check she is large enough to carry the transmitter – ideally over 400mg.
She is then encouraged to crawl up a long tube and a plastic pen-shaped tool is inserted into the tube to hold the hornet by her abdomen.
The transmitter is then hooked onto the petiole, or waist, of the hornet before she is released, in the hope that she flies back to her nest.
Using the receivers bee inspectors can track the hornet up to 0.6 miles (1km) away.
‘Major threat to honeybees’
The transmitter trial has been so successful that APHA has ordered three more kits from the manufacturers in Holland.
The new technology has come at a crucial moment in the UK’s fight against these invasive predators, which are seen as a major threat to honeybees and other pollinators.
With 53 nests found so far this year numbers are considerably up on last year and look set to break 2023 records when 72 nests were discovered.
All the nests that are found are sent to Fera Science laboratories near York, where scientists analyse the hornets’ DNA.
Recent DNA testing has shown that four queens discovered in the South East this spring were likely offspring of two nests destroyed in Udimore near Rye, East Sussex, and Coldred near Dover, Kent, last autumn.
Those nests were themselves offspring of nests found in 2023.
It is the first evidence of second-generation Asian hornets, also known as yellow-legged hornets, being produced in the UK.
However, the discovery is not considered strong evidence of an established population.
Ms Wilson said APHA was still hopeful it could eradicate the Asian hornet.
“We would have to have much, much higher numbers where we see clear DNA links from year to year, for us to have any evidence that says that this is now established in the UK,” she said.
She said it was unlikely the four queen Asian hornets discovered this spring were the only second-generation hornets to have survived.
There are miles of open countryside between their original 2023 nests and where the second-generation queens were found this year.
But she said they could not make policy based on speculation as “for all of our controls, we have to have that science backing, we have to have the evidence to deal with it”.
She called the new trackers “game-changers” in their work and said the speed at which nests could now be found would mean resources were freed up to find more nests.
The National Bee Unit is entering its busiest time of year in the fight against the yellow-legged Asian hornet. Queen hornets will be growing their colonies and establishing large secondary nests.
It is vital the secondary nests are found before the next generation of queens emerge and disperse in the autumn.
The small team of hornet detectives in the unit say they rely on the public to provide them with credible sightings.
Anyone spotting one is asked to take a photo and report it on the Asian Hornet Watch app.
