Feedback sought on release of weed killing creepy-crawlies

Environment Southland is seeking public feedback on a proposal to introduce two new biocontrol agents – Chilean flame creeper leaf beetle and Darwin’s barberry rust fungus.

Environment Southland is seeking feedback on a proposal to introduce a leaf-feeding beetle (Biaptea elquetai) for controlling Chilean flame creeper. Currently Environment Canterbury is doing the same with a rust fungus (Puccinia berberidis-darwinii) to control Darwin’s barberry. Feedback is being sought before applications are lodged with the Environmental Protection Authority.

Biosecurity and biodiversity operations manager Ali Meade said the use of biological control agents for exotic weeds had been an effective tool to reduce the infestations.

“Environment Southland has a strong history of being proactive in the biocontrol space, with 40 years of control in the region. It’s not an instant solution to Southland’s weed problems but it offers a cost-effective, environmentally low-risk and sustainable solution to weed control,” she said.

Chilean flame creeper and Darwin’s barberry are both prevalent in Southland. Chilean flame creeper grows into high tree canopies and blocks sunlight for plants below. Darwin’s barberry aggressively invades pasture and forest margins.

“Using organisms like bugs and fungi are proven to be effective in reducing infestations of exotic weeds. If approved by the Environmental Protection Authority these biological agents will help us in our fight to control the spread of these plants.”

Rigorous testing has been undertaken with both agents to ensure they do not harm native or desirable plants, Ali said.

“These tests included species that are related to Chilean flame creeper and Darwin’s barberry, as well as other species, such as different brassicas, which are of economic importance.”

“While there was some feeding on exotic garden plants, this can be managed by the use of insecticides. Laboratory testing on pak choi (Brassica chinesis) showed very limited feeding and larval development. However, given the testing conditions it was concluded that there was a low chance of the beetles spreading onto commercial crops.”

Further to laboratory testing, field surveys and literature reviews were conducted and found no evidence of attack by the beetle on brassica crops.

The Darwin’s barberry rust fungus was tested on 13 related species and found to only spread to Darwin’s barberry.

Alongside the two new proposals is a re-application for approval for the release of Darwin’s barberry flower weevil (Anthonomus kuscheli), which was approved in 2012 by the Environmental Protection Authority, but never released. The approval has since lapsed.

There will be two online seminars to provide further information on the Chilean flame creeper leaf beetle application on Tuesday, 22 October at 11am to 12pm and 7pm to 8pm. Email communications@es.govt.nz to register your interest.

Feedback can be submitted online via the Environment Southland website by Tuesday, 29 October for the Darwin’s barberry biocontrol agents and by 1 February, 2025 for the Chilean flame creeper leaf beetle.

Following the formal application to the Environmental Protection Authority there will be a public submission period.