Biocontrol introduction
Target pest: Tropaeolum speciosum (Brassicales: Tropaeolaceae), Chilean flame creeper
Agent introduced: Blaptea elguetai (Coleoptera: Chrysomelidae)
Imported:
2022
Import source:
Chile
Import notes:
Landcare Research (2023b) - sixty-five Blaptea elguetai adults collected from the field in Chile over several weeks, along with 450 eggs laid by those adults, were brought to Christchurch, New Zealand by Landcare Research’s Chilean collaborator in early-November 2022. The beetles continued to lay eggs throughout spring and summer, providing an excellent supply of larvae for host range testing.
Impacts on non-targets:
Landcare Research (2023b) - initial no-choice host range tests were carried out in containment in New Zealand during spring and summer 2022-23. Potential host plants tested included seven species of Tropaeolum [family Tropaeolaceae] (five climbing ornamentals and two species of nasturtium) and plants in closely related families, including the tropical species papaya [Carica papaya, family Caricaceae] and moringa [Moringa sp., family Moringaceae], and five indigenous and five commercially grown species in the family Brassicaceae. All Tropaeolum species were acceptable hosts, although the climbing species all produce foliage in winter, when Chilean flame creeper (Tropaeolum speciosum) and B. elguetai are dormant and no B. elguetai were found on these potential hosts in the wild in Chile. Of the plants tested from other families, one individual B. elguetai managed to develop to the adult stage on each of moringa, Chinese cabbage and pak choi [the latter two both cultivars of Brassica rapa]. Data analysis calculated the risk of moringa or Chinese cabbage becoming field hosts at less than 5%. The risk for pak choi was higher at 24%, warranting further investigation into this species next spring. However, the results overall suggest B. elguetai is sufficiently host specific for release in New Zealand.
References
Landcare Research (2023b). CFC beetle living up to its promise. Weed Biocontrol: What's New? 104, May 2023 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/cfc-beetle-living-up-to-its-promise/
