Japanese Butterfly To Be Released Soon
Honshu white admiral.
In the past year there has been great progress towards biocontrol for Japanese honeysuckle (Lonicera japonica).
In August the Environmental Protection Authority gave approval to release the Honshu white admiral butterfly (Limenitis glorifica). Greater Wellington Regional Council was the applicant on behalf of the National Biocontrol Collective. “The host-testing was done in Japan due to difficulties mating the butterflies in captivity here in New Zealand. The butterflies have an elaborate courtship flight which they were unable to achieve in containment. For some reason they could also not be successfully hand-mated either, even by an expert who was flown over from USA to assist,” explained Hugh Gourlay.
The host-testing was completed by Hugh and Quentin Paynter based at the National Institute of Agro Environmental Sciences at Tsukuba just north of Tokyo. “Maintaining a disease-free population of the butterflies was crucial to the project. This was achieved by collecting mated female butterflies in the field, keeping the eggs from each individual separate and line rearing those without disease symptoms,” explained Quent. A few tricks were learnt along the way such as the importance of keeping the females under good lighting and well fed while they were producing eggs. Japanese collaborators surprised Quentin by feeding the females a high energy sports drink ‘Pocari Sweat’ to keep them going!
The resulting disease-free larvae were shipped to New Zealand and are currently being held in containment at cool temperatures to allow them to be re-phased to our seasons. We have also imported several additional shipments of eggs sent by our Japanese collaborators to boost numbers. These eggs have been allowed to develop into larvae and pupae and when butterflies have emerged, and their identity has been confirmed, we have been sending them to a butterfly house in Auckland known as Butterfly Creek. The small number of butterflies released inside the butterfly house at the end of October appeared to happily take to their surroundings but laid infertile eggs. We did not confirm the sex of the butterflies before releasing them (to avoid handling and possibly damaging them) and it is possible the first batch were all females. We are still hoping for fertile eggs from later batches in which case we will collect and take them to our Auckland containment facility. This is to ensure that the larvae are not infected with any disease before releasing them in the field around December. Once establishment at field sites is achieved we will aim to harvest eggs and larvae to release in all areas where the white admiral is needed. “New Zealand’s climate is less extreme than Japan’s, and the butterfly is expected to do well throughout the country. The number of generations it might have in New Zealand is expected to vary from 2–3 in warmer parts of the country but perhaps only one generation in cooler parts of the country,” said Quent.
Further progress has also been made with other potential agents. Testing of a long-horn beetle (Oberea shirahatai) in containment at the Lincoln facility is nearly complete. The beetle, whose larvae are able to kill whole stems, shows a clear preference for Japanese honeysuckle and another weed Himalayan honeysuckle (Leycesteria formosa), with major ornamentals such as Lonicera nitida and Lonicera x heckrottii ‘gold flame’ at low risk of attack. We are planning to prepare an application to release the beetle soon and hope to submit it to the EPA around the middle of 2014.
Testing of a leaf-tying moth (Allotolanta sp.) has also been continuing in containment at Lincoln but has proven difficult. This moth will not lay eggs normally when caged, so we can’t undertake realistic oviposition tests. Testing using small larvae placed on cut stems has ruled out the majority of test plant species as possible hosts, but larvae have not survived for long enough using this method for us to adequately understand the risk to some species. Additional testing on whole plants of these species and/or some field testing in Japan will therefore be needed to complete host-testing.
Finally, another shipment of the foliage-feeding sawfly (Zarea lewisii) has been imported into containment for further study. “Difficulties in rearing the sawfly to the adult stage have prevented any host-testing from being undertaken to date, but we are having one last go at trying some new approaches to trigger adult emergence,” said Hugh.
This project was funded by the National Biocontrol Collective.