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

Vespa velutina nigrithorax is an invasive hornet introduced into Europe in 2004 that preys on invertebrates, including honey bees, posing a threat to European apiculture. In 2016, the first nest was detected and destroyed on mainland UK; a further eight nests were discovered between 2016 and 2019. All nests were dissected and analysed using microsatellites across life stages to assess reproductive output and success. None of the nests had produced the next generation of queens. Follow-up monitoring in those regions detected no new nests in subsequent years. Diploid males were found in many UK nests, microsatellite analysis showed low genetic diversity, and most queens had mated with one or two males. All UK nests derived from the European zone of secondary colonisation rather than the species’ native range, and none of the nests were direct offspring of another UK nest. The evidence indicates these were separate incursions from continental populations rather than a single established UK population.