Public reporting is essential for controlling the invasive yellow-legged hornet: a novel model simulating the spread of Vespa velutina nigrithorax and timescales for control in Great Britain

The invasive yellow-legged hornet (Vespa velutina nigrithorax) was introduced into France in 2004 from China and has now spread across western Europe and into Great Britain. Between 2016 and 2022, 13 V. velutina nigrithorax nests were sporadically found and destroyed in England. In 2023, 72 nests were found and destroyed by the Animal and Plant Health Agency’s National Bee Unit (NBU) inspectors across southern and northern England. In 2024, 24 nests were found and destroyed. To better understand the potential establishment of V. velutina nigrithorax in Great Britain, a model was developed to simulate its dispersal and the associated control efforts. We simulated public reporting based on the realistic distribution of observers in the landscape, the genetic load due to the presence of diploid males, and continued incursions into a freely breeding population. We estimated the number of years before officials tasked with locating and destroying nests became overwhelmed by the number of nests in the landscape. In the absence of reporting, an undetected population would be large enough to overwhelm control efforts after three to seven years (i.e. the person-days required to locate and destroy nests would exceed those available). When nests were reported by members of the public and beekeepers, control efforts could continue for at least 10 years before becoming overwhelmed – depending on the national reporting probability, the abundance of observers in the landscape, and the annual incursion rate

Managing incursions of Vespa velutina nigrithorax in the UK: an emerging threat to apiculture

AbstractVespa velutina nigrithorax is an invasive species of hornet accidentally introduced into Europe in 2004. It feeds on invertebrates, including honey bees, and represents a threat to European apiculture. In 2016, the first nest of this hornet was detected and destroyed on mainland UK. A further 8 nests were discovered between 2016 and 2019. Nest dissection was performed on all nests together with microsatellite analyses of different life stages found in the nests to address the reproductive output and success of nests found in the UK. None of the nests had produced the next generation of queens. Follow-up monitoring in those regions detected no new nests in the following years. Diploid males were found in many UK nests, while microsatellite analysis showed that nests had low genetic diversity and the majority of queens had mated with one or two males. All UK nests derived from the European zone of secondary colonisation, rather than from the native range of the species. None of the nests discovered so far have been direct offspring of another UK nest. The evidence suggests that these nests were separate incursions from a continental population rather than belonging to a single established UK population of this pest.</jats:p

The invasion, provenance and diversity of Vespa velutina Lepeletier (Hymenoptera: Vespidae) in Great Britain.

The yellow-legged or Asian hornet (Vespa velutina colour form nigrithorax) was introduced into France from China over a decade ago. Vespa velutina has since spread rapidly across Europe, facilitated by suitable climatic conditions and the ability of a single nest to disperse many mated queens over a large area. Yellow-legged hornets are a major concern because of the potential impact they have on populations of many beneficial pollinators, most notably the western honey bee (Apis mellifera), which shows no effective defensive behaviours against this exotic predator. Here, we present the first report of this species in Great Britain. Actively foraging hornets were detected at two locations, the first around a single nest in Gloucestershire, and the second a single hornet trapped 54 km away in Somerset. The foraging activity observed in Gloucestershire was largely restricted to within 700 m of a single nest, suggesting highly localised movements. Genetic analyses of individuals from the Gloucestershire nest and the single hornet from Somerset suggest that these incursions represent an expansion of the European population, rather than a second incursion from Asia. The founding queen of the Gloucestershire nest mated with a single male, suggesting that sexual reproduction may have occurred in an area of low nest density. Whilst the nest contained diploid adult males, haploid 'true' males were only present at the egg stage, indicating that the nest was detected and removed before the production of queens. Members of the public reported additional dead hornets associated with camping equipment recently returned from France and imported timber products, highlighting possible pathways of incursion. The utility of microsatellites to inform surveillance during an incursion and the challenge of achieving eradication of this damaging pest are discussed