Asian Hornets: measuring and modelling the new emerging threat to managed and wild pollinators

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The Asian Hornet (Vespa velutina nigrithorax) [AH] is an invasive alien species that is rapidly spreading through Europe. It is an important emerging threat to wild and managed pollinators, as it is a voracious predator of insects. Over 50% of its diet has been reported to consist of honeybees, wild bees and wasps. The AH live in large nests producing 5,000-20,000 individuals and the workers hawk for prey at bees' nest entrances, and flower patches, picking off foragers and shutting down foraging activity to the detriment of the colony. AH have caused significant damage to honeybee colonies in France and Italy with increased mortality of 5-80% where AH has established, threatening the viability of beekeeping and honey production. Of additional and immediate concern is the damage it could cause to wild bee and wasp populations, and the pollination services they provide to crops and wild flowers, but these effects have not been quantified.An AH nest was first found in UK in September 2016, another nest found in 2017, and a third found in September 2018, signalling that establishment in the UK is imminent. The only means of halting the spread, or limiting it, is to find and destroy nests as soon as possible. There is thus an urgent need to develop a method to locate nests efficiently for management of this pest. In a ground-breaking pilot project (funded by Defra) we have radio-tracked individual AH flying back to their (previously un-discovered) nests. Our first aim is to test the range of use of radiotelemetry, and combine it with a new acoustic monitor giving early warning of AH attacks at bee hives. We will design a protocol using these technologies to reduce the speed of AH invasion (Objective 1). Our second aim is to measure the potential impact of AH as a pest of managed and wild pollinators in three ways: measuring the impact of AH predating at bee colonies (Objective 2); measure the proportions of different pollinator species in the AH diet using DNA sequencing (Objective 3) and measure whether AH disrupt pollinator networks at flower patches (Objective 4). Work will be carried out in France and the Channel Islands which are at different stages of the invasion timeline. Data on AH foraging and predation rates will be used to forecast the likely impact of these predators on managed and wild pollinators in the UK, and estimate impacts on crop pollination (Objective 5) using our models of bee colony and population dynamics, BEEHAVE and bumbleBEEHAVE.It is essential that this research takes place as soon as possible: the best opportunity to slow a UK invasion is during the next few years. EU governments are looking for methods to slow the spread of AH, and beekeepers strongly advocate the need for investment in this work, (see Supporting Letters from Defra, DoE Jersey, and beekeepers). The ~250,000 honeybee hives in the UK are estimated to be worth £150 mill to the economy in honey and pollination provision. The AH could trigger losses of £30-45 mill per year, and our technology to detect nests early could reduce AH economic impact by at least £10-15 mill per year. This will be achieved by sharing our protocol and evidence with policy makers: to help manage the invasion and increase knowledge and skills amongst beekeepers, agencies and pest controllers. These actions, together with raised public awareness, will boost chances of early nest detection at the AH invasion front. The reduction in environmental impact will also be significant, because wild bees are under threat already, so that a further reduction in these communities is likely to affect their vitally important ecological function as pollinators.The assembled team of researchers at Univ. of Exeter (Osborne, Tyler, Kennedy & Chaput) and partners (French researchers, Defra, Dept of Environment Jersey, the BBKA & Jersey beekeepers) have experience in animal tracking, pollinator science, molecular ecology and practical AH management to succeed in these goals.