Progress in the classical biological control of Carpobrotus edulis for Great Britain

Carpobrotus edulis (Aizoaceae) is a succulent perennial native to South Africa, but invasive in southern Europe, Great Britain (GB) and Ireland, USA, Australia, and New Zealand. It spreads rapidly via creeping stems, forming dense mats. Favouring sandy soils, it thrives in coastal habitats, particularly dunes and cliffs. In GB, it has established itself along the south-western and southern coasts. Its vigorous growth outcompetes native flora, threatening biodiversity and altering the ecosystem structure and function of fragile coastal areas. Management is necessary to protect vulnerable sites but can be challenging in unstable or inaccessible locations. Following a Natural England stakeholder workshop in 2022, C. edulis was prioritised for biocontrol and a feasibility study was undertaken by CABI. This was followed by a survey to identify natural enemies of the plant in GB, including an introduced South African scale insect. The paucity of damaging and specific natural enemies in GB prompted a subsequent survey in 2023 to the native range of the plant, organised in collaboration with the Centre for Biological Control, Rhodes University, South Africa. An array of natural enemies were recorded, with scale insects and a pathogen brought to the UK for culturing and further evaluation. In 2025 and 2026 additional targeted surveys were conducted to collect two species of stem-mining beetles. Details will be provided on the status of the biocontrol study, and the natural enemies prioritised.