Japanese butterflies to combat pest weed
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Close-up of adult 'horned' Honshu caterpillar
Waipa District Council compliance officer Brigid Spears with Anton Hutchinson releasing caterpillars onto pest weed, Japanese Honeysuckle
Mangapiko Stream in Te Awamutu is now home to a raft of new international visitors working to combat weeds following a caterpillar release on Wednesday morning.
The caterpillars, originating from Japan, will grow into Honshu White Admiral butterflies which have a keen appetite for Japanese Honeysuckle, a serious environmental weed prominent around streams and rivers across New Zealand.
Waipā District Council’s service delivery group manager, Dawn Inglis, said the weed or pest plant has hindered riparian and native planting efforts in the district in the past.
“Our team has been looking forward to this day for some months and we are certainly pleased to be underway. We expect the butterflies to establish a viable colony in the Te Awamutu area over the next couple of years, which in time will move out into the surrounding catchments providing both environmental benefits and weed control assistance to landowners.
“With Honeysuckle growth under control long-term, we will be able to introduce new riparian planting next year which is part of our resource consent conditions for Te Awamutu Wastewater Treatment Plant.”
Japanese honeysuckle Lonicera japonica is an aggressive weed, featuring small yellow and white flowers, which typically blankets neighbouring vegetation as it climbs. Reducing the incidence of Japanese honeysuckle can help to partially restore natural vegetation, webs and ecosystems.
The caterpillars were released by Waikato RiverCare operations manager, Kevin Hutchinson, who manages riparian planting programmes across the Waikato region.
Honshu butterfly colonies have already been established in sites across the Waikato and Canterbury following successful trial releases. The released caterpillars are reared at Manaaki Whenua Landcare Research in Lincoln, Canterbury and have a lifespan of up to three weeks. White admiral butterflies survive on only a very narrow range of host plants and breed only under optimal conditions.
“Female honshu butterflies can lay up to 200 eggs each and the caterpillars have a good appetite for Japanese honeysuckle. Rather than spraying honeysuckle with herbicides, these caterpillars and butterflies are an excellent long-term biological control with proven results,” Hutchinson said.
The Environmental Protection Authority approved the release of the butterflies in 2013. This was the first of several proposed biocontrol agents that work together to help control Japanese honeysuckle in New Zealand. To learn more, head to the Landcare Research website: www.landcareresearch.co.nz.
Te Awamutu Wastewater Treatment Plant is currently being upgraded to cope with increased demand from a growing Waipā population and the introduction of wastewater flows from Waikeria Prison. Learn more at www.waipadc.govt.nz/your-waipa/majorprojects/te-awamutu-wastewater-treatment-plant-upgrade.
5,000 caterpillars ready for release
Close-up of adult 'horned' Honshu caterpillar