St. John’s wort beetles would not have been
introduced to NZ today!
Ronny Groenteman, Simon Fowler & Jon Sullivan
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
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
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
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?