Tasman beech forests have some of the highest Vespula wasp densities in the world and we all know getting on top of them isn’t easy.
For over 10 years we have been hard at it trying to find a solution. Last year, we released a small number of an approved biocontrol agent, the Volucella inanis hoverfly, at Wainui in Golden Bay and Ronga Valley in the Rai Valley.
The adult female hoverfly enters the wasp nest and lays eggs in larval cells. Once hatched, the fly larvae feed on wasp larvae and pupae. This technique could help to manage wasp populations and bring them down to a less harmful level.
This season, we’re planning to release another batch of hoverflies in the Howard Valley. So, what’s next for Wainui and Ronga Valley? Well, that’s the tricky part – seeing if last year’s release was successful.
And why is it tricky? Well, someone has to dig up wasp nests to find out. Luckily Bob ‘the wasp whisperer’ Brown from Manaaki Whenua is up to the task along with some keen folk such as Bronwyn Billens from Manawhenua ki Mōhua.
Unfortunately, our first two nests showed no signs of Volucella, but we’ll keep looking and keep releasing. We know biocontrols are a slow burn, but when successful can be a game changer.
This work is under the umbrella of the Kotahitanga mō te Taiao Alliance and is a collaboration between Manaaki Whenua – Landcare Research, Tasman District Council, Marlborough District Council, our iwi partners, and the Vespula Action Group, as part of a Ministry for Primary Industries Sustainable Farming Fund.
Support has also been provided by Manaaki Whenua’s Strategic Science Investment Fund and The Nature Conservancy Aotearoa New Zealand.