Phytophagous Organisms Associated with the Woody Shrub 'Polygala Myrtifolia' (Polygalaceae) and Their Potential for Classical Biological Control in Australia

Coastal ecosystems in southern Australia have been invaded by the South African shrub Polygala myrtifolia L. (Polygalaceae), leading to ecological disruptions and loss of biodiversity. Expansion of P. myrtifolia populations is expected unless effective containment or suppression activities are implemented. Low herbivory pressure in Australia compared to the species' native range is likely to have contributed to the invasion success of P. myrtifolia. Twenty-eight phytophagous organisms are recorded from P. myrtifolia in South Africa and six have potential as classical biological control agents, but require formal host specificity and impact evaluation. Further understanding of seed-bank dynamics and recruitment patterns of P. myrtifolia in Australia would contribute to the selection of suitable biological control candidates. Seeddestroying agents were not found on P. myrtifolia in South Africa, but additional survey effort is warranted as seed-destroying agents could alleviate conflicts of interest between environmental protection and the ornamental garden trade.