Biocontrol introduction
Target pest: Cytisus scoparius (Fabales: Fabaceae), Scotch broom, broom
Agent introduced: Arytaina genistae (Hemiptera: Psyllidae), stripy broom psyllid
Imported:
Landcare Research (2022a) - accidental introduction; first detected in New Zealand in 2019.
Import notes:
Landcare Research (2022a) - almost 10,000 broom psyllids (Arytainilla spartiophila), including many nymphs (which are similar in appearance to A. genistae nymphs), were imported from the UK into containment at Lincoln, Canterbury, during the 1990s as a biocontrol agent for C. scoparius. It is possible some A. genistae may have inadvertently been imported with the A. spartiophila nymphs. However, there were strict rearing and identification protocols to ensure that only adults of A. spartiophila were released, and exhaustive nationwide surveys post-release and up until 2017 did not identify any A. genistae. The most plausible introduction pathway for A. genistae into New Zealand is more recently as a stowaway on a boat or plane from either its native range in Europe, or its adventive range in the USA.
Released:
Landcare Research (2022a) - accidental introduction; first detected near Christchurch in Canterbury, South Island, in 2019.
Establishment:
Landcare Research (2022a) - in 2019 several A. genistae individuals were caught on sticky traps near Christchurch, Canterbury, South Island. Spring 2021 surveys not only found A. genistae close to the original detection site but also that it was common over the Canterbury Plains and Banks Peninsula. Other regions were not surveyed, and further surveillance is required to determine the distribution of this psyllid in New Zealand.
Impacts on non-targets:
Landcare Research (2022a) - in its native range in Europe, A. genistae can reproduce on other plant species that are closely related to Cytisus scoparius, such as Cytisus proliferus (tagasaste) and Genista spp.
References
Landcare Research (2022a). Broom delivers a psyllid surprise. Weed Biocontrol: What's New? 99, February 2022 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/broom-delivers-a-psyllid-surprise/
