New Wasp Approved To Counter Wattle Invasion

The Environmental Protection Authority (EPA) has approved the import and release of an Australian wasp to control the spread of an invasive wattle.

The decision to approve the bud-galling wasp ( Trichilogaster acaciaelongifoliae) follows comprehensive EPA assessments that found it will provide a highly specific and sustainable tool to control Sydney golden wattle ( Acacia longifolia).

Based on risk assessments and studies, the EPA considers it highly unlikely the wasp will displace or harm any native species.

The wasp, which is only a few millimetres long, does not sting or bite and there is no risk to human health.

"These wasps are quite docile and are only active for a few weeks a year. They prefer to remain near the host plant, further reducing any possible risk to our native plants and animals," says Dr Chris Hill, General Manager of Hazardous Substances and New Organisms.

Bud-galling wasps can control the spread of Sydney golden wattle by laying their eggs in flower buds, which induces abnormal growths (galls) that prevent flowers forming and seed production.

Since being introduced in New Zealand in the late 19th century, this invasive plant has spread broadly in the North Island and significantly reduced biodiversity in two of Aotearoa New Zealand’s most threatened environments - dunes and wetlands.

The wattle has had a similar negative impact on biodiversity in countries around the world. It also forms dense thickets that increase fire hazards in areas it invades.

"Risk assessments we carried out found that introducing this wasp as a biocontrol agent will help reduce the reliance on chemical pesticides to combat the Sydney golden wattle, in the long term, and allow native plant species to return," says Dr Hill.

"This will in turn reduce fire hazards, increase water availability and attract native animals."

Horizons Regional Council in the Manawatū-Whanganui region applied to import and release the bud-galling wasp on behalf of the National Biocontrol Collective, a group of regional and district councils and the Department of Conservation (DOC).

The EPA publicly consulted on this application and received 49 submissions, with 31 submissions in support,16 opposed, and two neutral.

Find out more about this decision: HSNO application register | EPA

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