ERMA New Zealand has approved the conditional release of two biological control agents that attack the weed Scotch broom (Cytisus scoparius).
The approval follows a public meeting last month in Christchurch, where ERMA New Zealand Authority members heard from the Canterbury Broom Group in support of its application t o introduce Broom Shoot moth (Agonopterix assimilella ) and Broom Leaf beetle (Gonioctena olivacea), to New Zealand. The insects feed on broom's green stems and leaves, and ring-bark its twigs and branches.
ERMA New Zealand Authority member, Kieran Elborough, said that on balance the Authority found the potential benefits of introducing the insects outweighed the risks.
"Potential benefits included a reduction in adverse impact of broom on habitats being managed for natural values; less cost for controlling broom for farmers, foresters and other land managers; and improved pastoral agriculture and forestry productivity," Dr Elborough said.
The Authority considered that while the insects may also feed on tree lucerne, a woody non-native shrub closely related to broom, and reduce this plant's potential use for soil protection, this risk could be mitigated through alternative plantings.
The risk that the beekeeping industry may need to find alternative sources of pollen for hives was also considered.
The Authority acknowledged the concern of some submitters that the native pigeon, or kereru, sometimes feed on broom, and its reduction could lessen its availability as a food source.
"However, the Authority concluded that kereru feed on a range of exotic plants, and that predators rather than food supplies were thought to be the main factor limiting kereru population recovery," Dr Elborough said.
Particular note was taken of community and iwi-led initiatives encouraging kereru populations. The Authority encouraged the applicants, as well as interested community groups, to observe local kereru populations and support programmes promoting the recovery of these bird populations through planting appropriate food plants.
For further information contact Helen Corrigan, Public Awareness, ERMA New Zealand
- Telephone +64 4 918 4835
- Mobile 021 151 9970
- Facsimile +64 4 914 0433
- Website: www.ermanz.govt.nz
Email: info@ermanz.govt.nz