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 trial Insecticide 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 NZ Australia

H. rubicundulum NZ endemic

H. pusillum NZ Australia

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. perforatumH. involutumH. pusillum Days to end of larval stage H. perforatumH. involutumH. pusillum % completed development C. hyperici C. quadrigemina H. perforatumH. involutumH. pusillumH. rubicundulumH. androsaemum Eggs per plant Groenteman et al., 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