BERN Swiss farmers are increasingly concerned by the impact of invasive species on agriculture. Europe currently has some 12,000 invasive species, both flora and fauna. While only 15% are considered dangerous or otherwise harmful, this is enough to threaten long-term food production. One of these is ambrosia, a weed introduced from North America during the 19th century but now firmly established throughout much of the continent. Its pollen not only affects crops, it also causes severe allergies among humans.
However, a more poignant invader which is beginning to worry beekeepers, doctors and environmentalists is the Giant Asian Hornet, also known as the Asian Killer Hornet. It has been spreading across southern Europe since 2004 and was first reported in Switzerland in 2013. The hornets follow the weather as it grows warm, or when there are summer storms. The wet conditions interspersed with sun over the past few weeks have proven particularly conducive. This year, possibly the result of climate change, more sightings have been made, particularly in the Geneva-Pays de Gex area but also Vevey and Montreux. While the hornets can presumably breed in Switzerland – some nests have been spotted – it is not known whether they are able to survive harsh winters.
Native to China and other eastern parts of Asia, this 3-5 cm long insect has distinctive yellow legs and is believed to have been introduced via imported plants, flowers, fruit and timber. Often making multiple stings if aggressed, the hornet now appears to be moving northwards. They are believed to have entered France via a shipment of Chinese pottery in 2004.
Doctors in China describe the hornet’s sting as being extremely painful, not unlike having one’s flesh pierced by a nail. It is also highly venomous given the large amount of poison injected. These highly predatory insects are a particular threat to honey bees, killing and consuming an average of 50 bees a day. Scientists warn that, if it becomes established, the hornet could decimate European bee populations, which already have been affected severely by pesticides. In turn, this would affect fruit tree pollination. Up to half of Europe’s bees in rural areas are said to have been lost over the past decade. As recently reported by Le News, however, bees appear to be doing well in urban parts, such as Basel, with gardens where pesticides are not used regularly.
The hornets have a tendency to swarm and a single aggressive hornet may immediately attract others. They then attack the victim as a band. While a single sting is not necessarily fatal, it can cause severe allergic reactions or renal failure. Multiple stings can prove even more dangerous. Scores of people die every year in China, while several deaths have been reported in France. Noting that the hornets have yet to establish themselves, one IUCN source suggested that people susceptible to allergies should consider stocking an emergency anti-allergy medicine. However, they should first check with their doctor. If a nest is found, one should immediately contact the police or fire department.