Tasman council to use hoverfly, beetle in war against invasive wasps

It's estimated the wasps cost the economy $133 million annually.
It's estimated the wasps cost the economy $133 million annually. Photo credit: Supplied / EPA

The Tasman District Council has upped the ante in the war against invasive wasps in the region.

Following an application by the council, permission has been granted by the Environmental Protection Authority (EPA) to import and release two new organisms - the wasp-nest beetle and a hoverfly, Volucella inanis - in a bid to reduce plague numbers of invasive German and common wasps in New Zealand.

Beech forests at the top of the South Island have the highest densities of wasps in the world, and it's estimated the wasps cost the economy $133 million annually, according to research quoted in the council's application.

The wasps kill honey bees and native insects, such as caterpillars and spiders, and cause problems for horticultural production, including grape and food crops. They also "pose adverse risks to humans", according to the application.

The wasp-nest beetle, Metoecus paradoxus.
The wasp-nest beetle, Metoecus paradoxus. Photo credit: Supplied / EPA

In a statement released on Tuesday, the EPA said approval to release the organisms was given because there is no evidence that either the beetle or hoverfly would attack non-target species, and there are no native or exotic species they could breed with.

The council said using the species as biological control agents would be a sustainable option to target hard-to-reach wasp populations.

"Invasive wasps pose a significant threat, having a negative impact on biodiversity and the food supply of native insects and birds such as kākā and tūī. The wasps also attack beehives, resulting in reduced pollination and honey production," Dr Chris Hill, the EPA’s general manager of hazardous substances and new organisms, said on Tuesday.

The approval came after a period of public consultation last year.