Tutsan Project Moves Towards Phase Two
One of the beetles (Chrysolina varians) that will be further investigated. Image - CABI Europe-Switzerland
The Tutsan Action Group secured funding in 2011 for a biocontrol programme against tutsan (Hypericum androsaemum). New Zealand surveys subsequently found little in the way of insect damage on tutsan.
Tutsan rust (Melampsora hypericorum) was common, but not providing sufficient control in the North Island. The reasons why were not well understood (e.g. is it due to environmental conditions, tutsan susceptibility, or pathogenicity of the rust?). However as phase one of the tutsan project draws to a close, information has been gathered that is helping to better understand the nature of the tutsan problem in New Zealand and what steps might need to be taken to improve control in phase two.
“Tutsan is not behaving in an invasive manner in the South Island but is becoming widespread in some regions in the North Island,” confirmed Hugh Gourlay. We have found that plants from the South Island, and some from Wellington, are genetically similar to some of those from southern England Scotland, Wales, Ireland, France and Spain. The other North Island populations share some genetic characters with those from Wales and Ireland. The main North and South Island types can sometimes be found growing together in the same location overseas. Some isolated plants in the Hawke’s Bay and Auckland are genetically different to other North Island material and each other. These plants are most likely the result of a deliberate attempt to breed tutsan in New Zealand since it was grown for ornamental purposes, rather than representing separate introductions from other parts of its native range.
Some interesting new information about tutsan rust has recently been collected. We have confirmed that there are two main strains of the rust present in New Zealand, with one type in the South Island and the other in the North Island. Stewart Island has both the North and South Island types. The South Island rust strain occurs widely across much of the UK, Ireland and France. The North Island rust strain is mainly found in Wales. Two other strains of the rust that are different to the strains present in New Zealand have been found in Spain and Georgia. “New Zealand tutsan will be assessed to see if it is susceptible to all of the rust types found in Europe and whether they offer any potential for improved tutsan control,” said Hugh. Already some preliminary testing has shown differences in the susceptibility of tutsan populations from the West Coast of the South Island and from Otago indicating there may be more subtle differences in tutsan populations in New Zealand yet to be resolved.
In addition to the rust work, CABI Europe-Switzerland has been undertaking surveys to look for other potential biocontrol agents. The most promising organisms found so far are three foliage-feeding beetles (Chrysolina spp.), which are similar to the highly successful St John’s wort beetles, two fruit/seed-feeding insects, a tortricid moth and a pentatomid bug, and a shoot tip-boring moth (Lathromorpha strigana). These survey results suggest that overall prospects for improving tutsan control in New Zealand are looking hopeful.
The Tutsan Action Group is currently preparing an application for funds for phase two of the tutsan project, which will be submitted in the next round of the Ministry for Primary Industries’ Sustainable Farming Fund (October 2013). If successful, phase two will get underway in July 2014 allowing at least one new biocontrol agent to be host-tested, imported cleared for release, and then mass-reared and field released.
This project is funded by an MPI Sustainable Farming Fund grant to the Tutsan Action Group, with contributions provided by other co-funders. The Tutsan Action Group is looking for co-funding to support phase two. If you are able to assist please contact the secretary, Ros Burton, at gtb@xtra.co.nz.