st. john’s wort beetles would not have been introduced to nz today! ronny groenteman, simon fowler...
TRANSCRIPT
St. John’s wort beetles would not have been
introduced to NZ today!
Ronny Groenteman, Simon Fowler & Jon Sullivan
St. John’s Who???
St. John’s wort Hypericum perforatum
• Introduced as medicinal herb• Severe pasture weed by 1930s• Toxic to live stock
• Programme started 1943• Most successful BC programme
BC agent removal trialInsecticide
Water
St. John’s wort biocontrol
• Why invest funds in an old successful programme???
• Post-release studies are pivotal to advance BC practice:– Safety– Effectiveness– Economics
Objectives
• Compare host-tests predictions to real world
• Demonstrate significance of BC agents
• Implications for future programmes
Retrospective host-range tests
• Indigenous species not included in original tests
• 4 indigenous species– 2 endemic– 1 critically threatened
H. involutum
NZAustralia
H. rubicundulum
NZ endemic
H. pusillumNZAustralia
We asked:
Would we have introduced St. John’s wort beetles
today?
Methods
• Laboratory host range testing• No-choice / choice arenas• Feeding • Development• Oviposition
Results
H. perforatum H. involutum H. pusillum
Da
ys
to
en
d o
f la
rva
l s
tag
e
0
10
20
30
40
50
60
H. perforatum H. involutum H. pusillum
% c
om
ple
ted
de
ve
lop
me
nt
0
20
40
60
80
100 C. hypericiC. quadrigemina
H. perforatum H. involutum H. pusillum H. rubicundulum H. androsaemum
Eg
gs
pe
r p
lan
t
0
5
10
15
20
25
30
35
Groenteman et al., 2011. Biological Control
Larval development
H. perforatum H. involutum H. androsaemum
H. rubicundulum H. pusillum
In reality…
• Little evidence of damage to indigenous species
• Significant displacement? Yet to be determined
• Benefits of control - enormous
• Recent review of successful programmes in N. America concluded: –St. John’s wort beetles would not have
been introduced nowadays
–More stringent regulations / interpretation of old regulations
–Monitoring crucial for data-driven benefit-risk decisions
Global context
Implications
• Risk rejecting effective & safe agents
• Control goals?
• Implications of failure to control?
USDA ARS - European Biological Control Laboratory, Bugwood.org
St. John’s wort beetles success