Testing the effectiveness of two biological control agents on Carpobrotus edulis
Carpobrotus edulis (EPPO List of Invasive Alien Plants) is native to South Africa and is a succulent species which invades temperate coastal areas around the world. The species has been shown to modify the abiotic environment and affect the composition, diversity and dynamics of native plant communities in different coastal habitats. Current control efforts to eradicate C. edulis using traditional methodologies, i.e. physical and chemical control, usually lack effectiveness and/or affect native plant species. To-date, biological control has not been applied against C. edulis in Europe. In a 6-month greenhouse experiment, two potential biological control agents the scale insect Pulvinariella mesembryanthemi (a highly specific insect feeding on the plant) and the fungus Sclerotinia sclerotiorum (a generalist pathogen native in Europe) – were tested to evaluate their effects on four native (South African) and four invasive (Iberian) populations. Five plants from each population were individually potted in a peat-sand mixture and assigned randomly to one of four treatments (control, fungus-inoculated, insect infested and fungus and insect-infested). Chlorophyll fluorescence and spectral reflectance parameters, as well as plant mortality, were recorded every month. Plants inoculated with the fungus showed significantly less photochemical efficiency and chlorophyll content than the control and insect-infested plants respectively, while plants infested with P. mesembryanthemi showed lower fluorescence yield and lower survival than control plants. The combination of both agents led to a higher chlorophyll degradation and to a lower survival than control plants.
Sources
Vieites-Blanco C, Retuerto R, Lema M (2017) Testing the effectiveness of two biological control agents on the invasive plant Carpobrotus edulis. Oral Presentation: Ecology and Management of Alien Plant Invasions (Lisbon, PT, 2017-09-04/08).