Biocontrol introduction
Target pest: Buddleja davidii (Lamiales: Scrophulariaceae), butterfly bush, buddleia
Agent introduced: Mecysolobus erro (Coleoptera: Curculionidae)
Imported:
1999
Import source:
China
Import notes:
Landcare Research (2007a) - specimens of M. erro, with no source location recorded, dated 1999, are present in the Biological Control Voucher Collection of the New Zealand Arthropod Collection [indicating an importation in that year].
Withers et al. (2010) - following preliminary host range testing in China, M. erro was imported from China into the Scion Invertebrate Quarantine and Containment Facility in 1999, where it was reared and further host range testing undertaken. The colony has since died out and it may not be economically justifiable to reintroduce it to undertake the multiple-choice testing that would be necessary to try and determine what the adult weevil’s plant feeding preferences might be in the field (see Withers et al. (2010) entry in ‘Impacts on non-targets’ section below).
Released:
Not released
Impacts on non-targets:
Withers et al. (2010) - preliminary no-choice host range testing undertaken in China indicated M. erro may be host specific to B. davidii. Additional no-choice testing in quarantine in New Zealand tested eight exotic Buddleja species (New Zealand has no native species in the genus) 15 plant species (eight indigenous to New Zealand) that either were or still are classified within the Scrophulariaceae, three exotic plant species from other families that commonly grow in association with B. davidii in New Zealand, as well as the host plant of one other Mecysolobus species. The results suggest the host range may be wider than B. davidii and include other species of Buddleja as well as Scrophularia and Verbascum. Of most concern, however, was the significant feeding damage on Parahebe hookeriana, Hebe salicifolia [now Veronica salicifolia] and H. diosmifolia [now V. diosmifolia]. Although self-sustaining populations could not arise on these native non-target species, tip dieback and significant disruption to flowering and seed-set could result from the M. erro adult feeding activity causing the petioles and stems to collapse and die. The palatability shown under no-choice conditions was high enough that multiple-choice testing on a high proportion of the species in these extensive genera is now required to ascertain the likelihood of damage in the field. In the absence of such data, it is unlikely the risk posed to the native flora by the introduction of M. erro would be considered justifiable.
References
Landcare Research (2007a). New Zealand Arthropod Collection (NZAC) Biological Control Voucher Collection. Landcare Research website [Updated 2020] https://www.landcareresearch.co.nz/tools-and-resources/collections/new-zealand-arthropod-collection-nzac/databases-and-holdings/new-t2-landing-page/
Withers TM, Gresham BA, Watson MC (2010). Will adult feeding damage rule out introducing Mecysolobus erro against buddleia into New Zealand? 17th Australasian Weeds Conference, Christchurch, New Zealand, 26-30 September 2010: 360-363 https://caws.org.nz/old-site/awc/2010/awc201013601.pdf
