Complete Host Testing with a Potential Biological Control Agent on Common Reed in View of Submitting a Petition for Field Release in Winter 2014/15.

摘要

The perennial grass Phragmites australis, or common reed, is considered highly invasive in North America. The native North American populations of common reed were recently recognized as a distinct subspecies, P. australis americanus. Investigations to evaluate the potential for classical biological control of the invasive reed type started in 1998. The CABI Centre in Switzerland was subcontracted to search for host specific natural enemies in the area of origin of P. australis. During the last few years, work concentrated on the two noctuid moths Archanara geminipuncta and A. neurica. Although both species can develop on native North American reed under no-choice conditions, lower oviposition and lower overwintering survival is expected on native compared to introduced reed. An open-field test established in 2013 with both moths confirmed a strong oviposition preference of A. neurica for introduced reed, but did not yield conclusive results for A. geminipuncta. The current contract provided funding to repeat the open-field test with A. geminipuncta in summer 2014 and to summarize results in preparation of a petition for field release in North America. Females of A. geminipuncta laid 312 (95.7%) of their eggs onto European and introduced reed, and only one egg cluster with 14 eggs on native reed. This clearly confirms the strong oviposition preference of the moth for native reed. Coupled with the fact that the eggs that are laid on native reed suffer a 40% higher overwintering mortality, we believe that any impact of Archanara species on native reed would be negligible. We are currently contributing to the petition for field release of A. geminipuncta and A. neurica, which is being prepared by Richard Casagrande (University of Rhode Island) and Bernd Blossey.