Karin Kos, Chief Executive, Apiculture New Zealand, said that yellow-legged hornets are aggressive predators of honey bees and other insects, including native bee populations.
Yellow-legged hornets (Vespa velutina) are known to have caused damage to honeybee colonies in other countries. This is mainly through predation on foraging honeybees at the beehive entrance.
This ‘hawking’ by the hornets can eventually stop honeybees from collecting pollen and nectar, increasing the risk of starvation. Honeybees in New Zealand (Apis mellifera) do not have any adapted defences against hornets.
In Europe, studies have found that 40 percent of the yellow-legged hornet’s prey are honey bees. In Portugal, for example, they have reported a slump in honey production of more than 35 percent in some regions. At the same time, France has estimated an annual economic loss of around $33 million due to the hornet.
The hornet is not just a threat to honey bees; it also preys on other insects, such as butterflies, moths, and native bees (of which there are 27 species vital to the pollination of our native fauna). This is not only a threat to biodiversity, but it also disrupts local ecosystems and pollination services.
Bees are crucial for pollinating many crops in New Zealand, from kiwifruit, pipfruit, stonefruit and avocados. They are also important to pastoral farming, as white clover pollination provides an alternative nitrogen source.
High country farming, in particular, is a heavy user of white clover nitrogen regeneration, which flows down to our sheep, beef and dairy trade, for example.
It is conservatively estimated that the economic value of bee pollination services in New Zealand is around NZD five billion a year. In addition, the honey export industry is worth around NZD 400 million annually.
“So while we don’t yet have the likely economic cost of the hornet should it become established in New Zealand, it has the potential for being a serious issue for the apiculture and broader agri-horticulture sectors,” said Kos.
“The key impact would be on honey production (and the cost involved in replacing hives) and pollination. Undoubtedly, there would be serious economic losses if the hornet became established in New Zealand.”
Kos added that there is also the cost to beekeepers of replacing hives and managing the incursion, at a time when the industry has been dealing with challenging conditions over the past few years, which have seen hive numbers fall by 50 percent in the last six years to around 480,000 today.
According to Kos, intensive surveillance around the incursion zone is critical at this time and this needs ongoing public engagement. Biosecurity NZ has been working to ensure widespread public awareness and targeted engagement with residents on Auckland’s North Shore in the area where these hornets have been found.
The industry is also in constant communication with beekeepers to be vigilant. The best surveillance tool right now is for people to report any sightings of suspected hornets or hornet nests online or through the pest and disease hotline.
“We cannot afford to be complacent if we are serious about eradication, and resources must be allocated to raise awareness and to trap and destroy the pest with urgency.”
As part of the response, Kos added that it was also important to learn from other countries’ experiences and was pleased that Biosecurity NZ has engaged scientific advisors (Technical Advisory Group), including overseas experts, to support the response.
“In addition, as an industry, we meet regularly (daily at this stage) with Biosecurity NZ to ensure our sector is well informed as we collectively deal with this serious incursion.”
To support surveillance, Biosecurity New Zealand has laid traps in a measured way in areas where females have been found. Members of the public and beekeepers are urged to report any suspected sightings via the exotic pest and disease hotline on 0800 80 99 66.
