Assessment of natural enemies for Carpobrotus edulis biocontrol.
Abstract
This report details a biological control feasibility assessment for Carpobrotus edulis (Aizoaceae), an invasive plant threatening sensitive UK coastal habitats. The study, commissioned by CABI after a 2022 stakeholder workshop, identified potential natural enemies, including the scale insect Pulvinariella mesembryanthemi, which has had significant impacts on C. edulis in California, USA. Surveys in Cornwall and the Isles of Scilly located this scale insect but found it in low densities with minimal impact. However, laboratory studies showed that under warm conditions, the scale could reach high densities and cause plant death. A climatic suitability assessment using CLIMEX confirmed that large parts of southern UK are favorable for the scale's establishment. Additionally, a related invasive plant species, Disphyma crassifolium, was found susceptible to the scale. The report recommends further host range assessments, potential rearing and redistribution of the scale, and surveys in South Africa to identify additional biological control agents. Research partnerships in South Africa have been established to support this effort.