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Biological Control of Invasive Tree Species

Worldwide, invasive alien species are regarded as 2nd only to habitat destruction as a key driver of biodiversity loss. This threat is particularly prevalent in the Fynbos biome “biodiversity hotspot” of South Africa. Concerted efforts to manage invasive alien tree species in South Africa, through a poverty relief initiative called “Working for Water”, have received international attention. It is however widely recognized that these efforts cannot succeed unless they are integrated with biological control as a management option.

A core group of PCU researchers, working in collaboration with the Agricultural Research Centre – Plant Protection Research Institute in Stellenbosch, practice biological control targeting invasive perennial trees. This project is funded through the South African Department of Environmental Affairs, National Resource Management Programmes.

All aspects of a “weed biological control” programme are entailed, but particular emphasis is placed on long term monitoring of the efficacy of the introduced biological control agents and the gains accrued for management. A core component is to disseminate information to stakeholders to ensure that informed management decisions ensue.

Pod production of Black wattle before and after the introduction of a small fly (insert) which causes the flowers to form abnormal growths instead of pods. (Photos left to right: JH Hoffmann, JH Hoffmann & PM Müller, CA Kleinjan.)