Horizons Regional Council granted consent to release non-stinging wasp

The bud-galling wasp lays its eggs in Sydney golden wattle flower buds. The eggs then produce growths that prevent seed production. Photo / Supplied

Horizons Regional Council, on behalf of the National Biocontrol Collective, has been granted consent to introduce a bud-galling wasp (Trichilogaster acaciaelongifoliae) to control the invasive pest plant Acacia longifolia, more commonly called Sydney golden wattle.

Horizons biodiversity and biosecurity manager Craig Davey says he is pleased approval has been granted because that means controlling the golden wattle can soon begin.

“This application has taken some time to ensure that there will be no negative implications from the wasps’ introduction,” he says.

“The Environmental Protection Authority has agreed that the wasp will not breed with other insects, or pose a threat to native species.

“This friendly wasp has no bite or sting and has already been through rigorous testing in South Africa and Portugal before the respective countries successfully released the wasp to control Sydney golden wattle.

“A biocontrol insect such as the wasp is the best approach to managing golden wattle effectively because it works by laying its eggs in flower buds, which then produce growths that prevent seed production,” Davey says.

Using the wasp to control golden wattle takes time, but will dramatically reduce its spread and allow for a more natural transition to resilient native plant-dominated dunes.

The application received strong support from coastal communities.

“We’d like to thank those that took the time to submit in support of the application. These, alongside the scientific research, helped get the release of the wasp over the line.”

Golden wattle was introduced to New Zealand as an ornamental plant and had established itself by 1897.

The pest plant grows well along our coasts and has significant negative impacts on this environment. It suffocates native species, preventing their growth to create what is known as a monoculture, meaning that only the golden wattle can thrive, Davey says.

“Coastal communities have been the motivating factor behind securing the wasp. They’ve experienced first hand the devastating impacts on dunes with the golden wattle covering coastlines from Whanganui to Waikawa. Others are likely familiar with the plant, especially in places like Himatangi Beach where the infestation covers most of the dunes, although they may not realise it’s a pest.”