Asian Hornet, (Vespa Velutina, Yellow Legged Hornet) may not get the same media coverage as its cousin the Giant Asian Hornet (AKA the Murder Hornet), but for honey bees and other pollinators, the risk it presents is just as great.
It is believed that Vespa Velutina made its way to Europe by accident, nestled in boxes of pottery in 2004. The invasive species has since spread at a rate of between 75 to 82 km/year. It is this ability to expand to new areas that makes it such a formidable threat. Since its first introduction in France, it has expanded to over 3 quarters of the country. By 2010 it had made its way to Spain and by 2011 its presence was confirmed in Portugal. As of 2022, Vespa Velutina has been found in Italy, Germany, the U.K., Belgium and Switzerland.
The main threat presented by the Asian hornet is the impact it has on invertebrates, in particular honey bees which constitutes a large part of its diet. The hornet hunts by forming a perimeter around the target beehive, then picking off workers as they enter and exit. Whereas Apis cerana has developed various defence mechanisms such as bee balling, creating physical barriers and intimidating behaviour such as abdominal shaking, the defence efforts of Apis mellifera have so far proven far less successful. The loss of workers due to predation then results in weaker colonies. In areas of France with heavy populations, it is estimated that hornets can be responsible for 20 to 30% colony loss.
Although the Asian Hornet is not more aggressive towards humans than the European variety, its abundance in infested areas leads to more interactions. In 2017 a man in Spain died due to being stung more than 20 times while pruning an apple tree. Several people have also died in Southwest France because of hornet attacks.
Controlling the spread of the Asian hornet has been a challenge. The most effective method to date has been nest destruction. Other methods such as traps have been tried, however as they are not able to discriminate between Asian hornets and other insects, they are generally not recommended. The Sarracenia purpurea, or the Purple Pitcher Plant, is a carnivourous plant that has also been investigated as a biological control method. However, as the plant is just as unselective and is also foreign species, it is not recommended.
Organizations such as CABI, LIFE STOPVESPA and APHA are investigating all reports of the Asian Hornet. Nest dissection, DNA sampling and micro satellite analysis allow scientists to track colony size and life stages, and to determine the genetic makeup of the colony. This provides insight into where the nest has come from and where populations are already producing subsequent generations. These monitoring methods, coupled with the practice of nest destruction are the best hope we currently have against the spread of the Asian Hornet.
Resources
Managing incursions of Vespa velutina nigrithorax in the UK: an emerging threat to apiculture
Eleanor P. Jones, Chris Conyers, Victoria Tomkies, Nigel Semmence, David Fouracre, Maureen Wakefield & Kirsty Stainton. (2020)
Rapid spread of the invasive yellow legged hornet in France: the role of human-mediated dispersal and the effects of control measures. Robinet, C., Suppo, C. & Darrouzet, E.J. Appl. Ecol. (2016).
Searching for nests of the invasive Asian hornet (Vespa velutina) using radio-telemetry. Kennedy, P. J., Ford, S. M., Poidatz, J., Thiéry, D. & Osborne, J. Commun. Biol. (2018).