Host Range and Impact of , the First Potential Biological Control Agent for in North America and Australia.

We evaluated the potential of the European root-feeding moth as a biological control agent for the invasive weed (oxeye daisy) in North America and Australia. The taxonomic proximity of the ornamental Shasta daisy () to and its popularity in North America made finding sufficiently host-specific biological control agents a challenge. No-choice tests conducted with 74 non-target species revealed partial or complete larval development on 11 species. In multiple-choice oviposition and larval development tests that were conducted in field cages, larvae were found on five of these, however in multiple-choice tests conducted under open-field conditions, larvae were only found on the ornamentals Shasta daisy and creeping daisy (). Larval feeding by had no measurable impact on Shasta daisy, but larval feeding and plant competition reduced the biomass and number of flower heads of . We conclude that is a suitable biological control agent because it will not affect the ornamental value of Shasta or creeping daisies and because it is unlikely to feed on any other economically important or native species. We also expect to contribute to the suppression of populations.