APP202663: import and release the moth,
Lathronympha strigana and the beetle,
Chrysolina abchasica, as biocontrol agents
for tutsan, (Hypericum androsaemum)
David Havell
Technical Advisor, Northern Threats Team,
Department of Conservation.
Tutsan Bicontrol Programmes
• The Department of Conservation
supports biocontrol programmes
where the agents have a targeted
impact and do not adversely impact
on native species.
• We support the release of
Lathronympha strigana for the
control of tutsan.
• We have concerns about releasing
the beetle Chrysolina abchasica.
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Will Chrysolinia abchasica cause Significant Displacement of any
native species within its natural habitat?
(Minimum Standards, HSNO Act, section 36)
(a) Tutsan alone, Rangitoto
Habitat overlap, between nationally
critical species and St John’s wort.
(b)
(d) Native Hypericum alone.
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Habitat overlap between native hypericum
and Tutsan, Puhoi
(c )
Self Sustaining populations
Could C. abchasica form self-sustaining populations in NZ?
We think where Tutsan and St John’s wort are present ,a self sustaining
population will occur and any release should assume so, so that a
precautionary approach should be used.
Distribution of Tutsan and St JW,
from both DOC and the NZ Virtual
Herbarium
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Tutsan cliff site,
Taumaranui Rest area
Concerns re Chrysolina species
1. Are known to have reduced St JW from a widespread
invasive species to occasional patches in NZ and elsewhere
2. Use Hypericum species across a range of Hypercium
sections, including taxonomic sections found in NZ.
Chrysolina abchasica will have one main host (tutsan), as
well as two other limited hosts (St JW and H. humifusum )
from which spillover and limited grazing may occur.
3. Spillover attacks of Chrysolina species on non target
species are known, for example Groenteman, lists records
of severe spillover attacks of Chrysolina species on tutsan
in NZ, even though the Chrysolinia species concerned did
not complete development on tutsan in trials
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http://www.sciencedirect.com/science/article/pii/S10499644
11000156
Concerns re Chrysolina species
4. If the effectiveness of biocontrol was carried across to non
target species, significant declines in native and valued
Hypericum species could be expected.
5. Tutsan and other exotic hypericums overlap in range with
native hypericums.
6. New Zealand has native hypericums which are valued and
threatened.
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Hypericum phylogenies
Published phylogenies of hypericum, with known Chrysolina hosts indicated.
Hosts occur across sections, though the best host tends to be 1 species.
Three, possibly 4 native species are likely to be used as hosts to varying
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degrees.
NZ Threat System
http://www.doc.govt.nz/Documents/science-and-technical/sap244.pdf
If hypercium natives declined at the rate St JW did,
a species threat ranking would significantly worsen
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This table shows categories factored into threat
rankings: population losses affect threat rankings
Chrysolinia grazing on Hypericums
C. abchasica (Landcare response to submission)
These tables show the
evidence of Chrysolina
species feeding on native
hypericums and feeding
instances. They graze
with intensity from
medium to high.
Current biocontrol agents for St John’s Wort, (Groenteman,2011)
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Chrysolina as vectors of plant disease
As noted by Landcare Research, Chrysolina spread
anthracnose disease which contributes to the
biocontrol of St John’s wort. Chrysolina species in
NZ including C. abchasica graze native Hypericums
and could spread disease via grazing damage.
Although unlikely disease carrying C. abchasica will
be released, beetles could become infected after
release with disease present in NZ.
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Do Hypericum species overlap in range?
Hyperciums,
Central North Island
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Yes.
And this is demonstrated with
just a small sampling of sites.
Matea Road
St John’s wort
H. minutiflorum
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H. pusillum
Pureora, Hypericum minutiflorum
site
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South Island Sites
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What does the Department of
Conservation want?
In order to be confident that there is not going to
be native species declines in areas where
C.abchasica hosts occur.
• We would like additional testing
similar to that published for other
Chrysolinia species.
• and more extensive reporting on
potential severe spillover impacts
on non target plants.
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Conclusions
1. Native hypericums, especially H. pusillum
grow in regions where tutsan and other
(albeit weaker) Chrysolinia hosts grow.
2. Native hyperciums are grazed by
Chrysolinia and some support limited
larvae development.
3. There is risk posed to native hypericums
by C.abchasica.
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Conclusions
4. The impact of C. abchasica and other Chrysolinia species
on native hyperciums needs further research, before a full
release is carried out .
5. Research should determine in what ways all native
Hypericums are affected by C. abchasica, including
whether there are local declines of native species, the
extent of decline, and plant damage in response to the
number of Chrysolinia individuals.
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