Giant hornets from Asia - risk of negative impact on honeybees and biodiversity
Report no: 2022: 03
As the climate warms it is possible for the Asian giant hornet (Vespa velutina) to spread to Norway, and unlikely for the Japanese giant hornet (Vespa mandarinia) to do so.
However, should the two species of giant hornets enter Norway it is more likely for the Japanese hornet to become established than it is for the Asian hornet.
This is the conclusion of VKM in its assessment of the risk to biodiversity and to honey bees in Norway, should the two hornet species establish and spread.
There are several uncertain aspects regarding the likelihood of introduction and spreading of the hornets. First and foremost, it is uncertain whether the climate in Norway is suitable for the two alien species.
Of the two, only the Asian giant hornet is already established, and spreading, in Europe. However, due to climatic preferences, it is still more likely that the Japanese hornet will be able to establish in Norway, should it get here.
Hazards and general risks
VKM has identified five possible hazards related to establishment and spread of the two species, and has assessed the likelihood of realization of these hazards.
Both species are predators and can destroy local honey bee colonies. This would have a negative impact on the production of honey and beeswax, and on pollination, especially of fruit trees. VKM has assessed that both species pose a moderate risk to honey bees in Norway.
According to VKM there is also a moderate risk to Norwegian biodiversity, and especially to hymenopterans, due to predation.
“The native European hornet could suffer due to competition for food and nesting sites, and we conclude that this risk is low to moderate, “says Katrine Eldegard, Scientific Leader of the project group.
Both the Asian and Japanese giant hornets can introduce or spread pathogenic organisms. Due to the lack of data, VKM has not assessed this risk in relation to the Japanese hornet.
The risk arising from the spread of pathogens from the Asian hornet is low, according to VKM.
VKM has summarized possible measures to reduce the risk posed by these hornets. VKM points out that both species are highly capable of spreading on their own. In addition, the species spread through the transport of goods. Over time it may be nearly impossible to stop these species from entering Norway, according to the risk assessment.
“In order to hinder establishment, it is important to detect and destroy individuals as early as possible. The likelihood of early detection is highest if the public is informed and involved,” says Eldegard.
“Should one of the species establish in Norway, we will need targeted measures to fight it off. It is possible to eradicate the hornets, or at least to reduce their presence around honey bee hives, but caution is needed to avoid having a negative impact on native species,” Eldegard adds.
The report also discusses various actions that beekeepers can take to safeguard their bee colonies.
The VKM Panel on Alien Organisms and Trade in Endangered Species (CITES) has assessed and approved the risk assessment.