Japanese Honeysuckle Project Back On Track
White admiral adult.
Some of the challenges we have encountered trying to develop biocontrol for Japanese honeysuckle (Lonicera japonica) have been strange, unexpected and downright unlucky!
We last reported on this project in Issue 54 after seeking the help of Professor Austin Platt to hand-pair and rear the white admiral butterfly (Limenitis glorifica). But even the “master mater” was unable to get the butterflies to perform. Since then, two signifi ant events have compromised the project. Firstly, the earthquakes that struck Christchurch in September 2010 affected the containment facility where populations of potential agents were being held. We had a stem-boring longhorn beetle (Oberea shirahatai) and an unnamed leaf-tying moth in containment and had begun host-testing them. We were getting good results but unfortunately both colonies were lost when the facility overheated.
Following this, the earthquake and tsunami in Japan 6 months later destroyed access to many of the collection sites used by our staff to source the insects and some of the sites were totally destroyed. In May 2011, the travel advisory recommended no travel north of Tokyo, which is where Quentin Paynter and Hugh Gourlay needed to go to restart the project. The unstable nuclear situation, in combination with the risk of ongoing aftershocks, meant it was not safe to undertake the work, and we decided to pause the Japanese honeysuckle project for a year. Because the work is seasonal, we needed to wait until June 2012 before another opportunity arose to collect and test Japanese honeysuckle agents.
The difficulties with rearing white admiral butterflies in captivity meant that host-range testing had to be done in Japan using field-collected eggs and larvae. Hugh and Quent were able to return safely to Japan in June this year and ship potential host plants from New Zealand to test the host specificity of the butterfly. The no-choice tests have now been completed and indicate that this species is sufficiently specific to honeysuckle to go ahead and apply for permission from the Environmental Protection Authority (EPA) to release the butterfly in New Zealand. As Quent reports, “New Zealand has no native plants in the Caprifoliaceae family and so gaining permission for their release should be relatively straightforward in light of the hurdles already encountered during this project.” The butterfly did successfully rear through on Himalayan honeysuckle (Leycesteria formosa), which is also an invasive weed in New Zealand (so a bonus), but not on the mostly commonly grown ornamental Lonicera (Lonicera nitida), which appears to have leaves that are too tough for the first-instar larvae to chew on. Other ornamental climbing forms of honeysuckle grown in gardens here with softer leaves may be attacked by the white admiral given the testing results, but attack on other Lonicera species in Japan has rarely been recorded and is considered exceptional. If this attack does occur, home gardeners may not mind if it means having an attractive butterfly in residence. These and other issues will be addressed in the EPA application, which will be prepared soon.
Hugh and Quent also collected some of the other potential control agents for Japanese honeysuckle. Twenty cocoons of the leaf-feeding sawfly (Zaraea lewisii) were collected and are now in containment in Lincoln while we wait for them to mature. We have learnt that they remain as prepupae for a long time and may need to be kept for up to 2 years before they will pupate, so it may be some time before we know if we will be able to successfully work with this species.
Some adult stem-boring beetles were collected again and have been caged on mature honeysuckle plants in the Lincoln containment facility. The inoculated plants have been busy creating plenty of sawdust so it is hoped that plenty of beetles emerge in due course to begin host testing in 2013. The leaf-tying moth has been tentatively identified by research associate John Dugdale as Allotalanta sp. or Scaeosopha sp. and it appears to be a new moth species for Japan. Eggs of the moth have been successfully reared through in containment and their offspring have been used to set up no-choice host specifi city tests. “The preliminary results indicate that the moth is specific to the Caprifoliaceae family of plants but more extensive testing will be required to confirm this,” says Quent. This testing will be undertaken in 2013.