JERSEY has seen an ‘astronomical’ rise in Asian hornet queens caught this year, fuelling concerns over the number of nests that could be found later this summer.
Last year, 55 queens were caught in traps with a record 174 nests subsequently discovered – so far this year 438 queens have been caught across the Island, and the cooler spring means that they are still being found, trapped or reported.
However, Asian-hornet co-ordinator Alastair Christie said it was too early to say what this might mean for nest numbers. He pointed out that every queen caught now represented the potential of a nest that would not have to be dealt with later.
‘It is an unprecedented, astronomical increase for us on the face of it, but what we don’t know is the number we are not catching and the number that will go on to build nests,’ Mr Christie said.
He explained that the Island was currently in a transitional phase when some Asian-hornet queens were still ‘out and about’ – and therefore vulnerable before they established nests – before worker-hornets emerged from developed nests.
‘I think all we can say about this year’s trapping programme is that every single queen that we take out now by trapping, or is caught by a member of the public, is potentially one less nest to deal with later on. It won’t translate exactly because, of course, there are all sorts of risks and factors between going from a queen now to producing a large successful nest, but it has to be true that catching 438 queens has saved ourselves an enormous amount of work later on of tracking the nests and then removing them,’ he said.
On average, it takes 25 to 30 hours to track down and deal with a nest, while some more difficult cases can take up to 150 hours. Flourishing nests have a harmful effect on native honeybees and the pollinating insect ecology, as well as posing a risk to Islanders of being stung by worker hornets attending those nests.
Quantifying the impact of volunteers working with the government to combat the Asian-hornet threat, Mr Christie pointed out that if, say, 200 of the 438 trapped queens had gone on to produce nests, they would have eventually contained close to half a million worker hornets in the environment.
However, he acknowledged that it was difficult to relate the number of trapped queens to the number of nests that would emerge. In 2021, 101 queens were discovered, while the number of nests was only 63. However, the 2022 figure of 55 queens caught related to more than three times as many nests later identified.
‘A question that we have asked – but we do not have an answer to – is why did we have so few queens last year, when clearly there must have been more of them around to eventually produce the higher number of nests?
‘Despite catching 438, we may find that there are as many, if not more, nests than last year.
‘We just don’t know at the moment – it could even be fewer. Some sense of this will become clear through July as we start to receive the reports of worker hornets,’ Mr Christie said.
To complicate matters, there was also a significant increase this year in the number of traps being monitored by volunteers and members of the public – from 215 to more than 300.
Mr Christie added that they were hoping to increase the 80-strong team of volunteers and that anyone interested could obtain further information using the contact details for sightings of Asian hornets by emailing asianhornet@gov.je or calling 441633.
