Greymouth High School students releasing Honshu white admiral butterfly caterpillars. Image: Murray Dawson
is a Decile 4 school with a total roll of some 500 students. 34 Year 12 students from two biology classes, taught by Morag Newberry and Tom McGirr, arrived by bus and assembled in the Paroa Hotel conference room. Their trip provided a good opportunity for the students to engage with researchers from Manaaki Whenua – Landcare Research (Hugh Gourlay and Murray Dawson), along with local representatives of the Guardians of Paroa Taramakau Coastal Area Trust (Fran and Kevin Cohen, and Wendy Ross), Department of Conservation (Rachel Nieman, Greymouth weedbuster ranger, and Bronwyn Slack) and West Coast Regional Council (Juliette Curry, biosecurity co-ordinator).
In the conference room, Hugh gave a couple of lectures explaining about biocontrol methods for weeds and more specifically biocontrol of Japanese honeysuckle.
In his first PowerPoint, Hugh explained to the students that a new plant species naturalises every 39 days and that there are now more naturalised than native species. Hugh also discussed the methods of collecting potential biocontrol agents from their native ranges in other countries, rearing them under containment, host testing to ensure they don’t feed on non-target species, and the economic benefits of biocontrol programmes.
Hugh’s second PowerPoint concentrated on potential biocontrol agents for Japanese honeysuckle, collecting Honshu white admiral butterflies in Japan, and their subsequent approval for release by the NZ Environmental Protection Authority. Hugh also passed around a container of adult butterflies to examine.
Murray then spoke briefly about the resources on weeds including the free Weedbusters handouts for the students.
After a safety talk by Fran Cohen, it was then time for us all to walk to the nearby release site behind Paroa Hotel. This site was along a gravel road that follows the coastline a few hundred metres, south-west of the Paroa School release site two days ago.
Hugh spoke to the students on-site and helped them make the releases – this was full release of another 1,000 or so caterpillars.
In the time remaining, we broke into groups and discussed the native and weedy plants found in the area – what they were, if they were native or weedy, and for the weeds, what country were they from, and why were they weedy. It was great to see that some of the students had installed the iNat app and were having a go with it.
What were some of the plants that we found?
The release site, along a gravel road, was a disturbed scrubland habitat sandwiched between the coast and a creek. In addition to Japanese honeysuckle (Lonicera japonica), other weeds dominated including blackberry (Rubus fruticosus complex), broom (Cytisus scoparius), gorse (Ulex europaeus), Montbretia (Crocosmia × crocosmiiflora), privet (Ligustrum) and tree lupin (Lupinus arboreus). Tradescantia (Tradescantia fluminensis) was surprisingly common too – perhaps Paroa would be a good future site for tradescantia biocontrol beetle releases?
Some interesting and less common weeds were also discovered. A large shrub of hardy fuchsia (Fuchsia magellanica) was found at the start of the gravel road, quite inaccessible being nestled between a creek lined with harakeke and a blackberry thicket. This South American species is related to but easily distinguished from native New Zealand fuchsias which have less showy and abundant flowers. Off the gravel road was a site that had obviously been used for disposing of garden waste. Growing from these discards was a Yucca, a weedy escape well adapted to the barren habitat, and illustrating how weeds can spread from roadside dumping.
Native plants were present near the release site too, including harakeke (Phormium tenax), common along the creek banks, New Zealand cabbage tree (Cordyline australis), five finger (Pseudopanax arboreus), māhoe (Melicytus ramiflorus), and pōhuehue (Muehlenbeckia australis). Pōhuehue is a vigorous native climber that competes with Japanese honeysuckle – it’s understandable that it is often confused for an exotic weed.
Further afield, there are numerous observations made on the iNaturalist platform of life found in the Paroa-Taramakau coastal restoration area, this stretch of the West Coast Wilderness Trail, and around the New River / Kaimata Lagoon.
