Earlier events :: 2013 :: STUDENT Talks

Exchange of pests and pathogens associated with a native and an invasive legume tree in the Cape Floristic Region, South Africa.

Presented by
Dewidine Van der Colff
University Of Stellenbosch
Dewidine Van Der Colff A, Leanne Dreyer A, Francois Roets A & Jolanda Roux B. A Stellenbosch University, Cape Town & B University Of Pretoria, South Africa. Email: Dvdc@Sun.Ac.Za


The Cape Floristic Region (CFR) has a high level of floristic diversity; however it is threatened by invasive alien plant species (IAPS). Little is known about the pests- arthropods and pathogens- ophiostomatoid fungi associated with these IAPS. Less is known about the potential exchange of these pests and pathogens between native and IAPS. In this study we surveyed a native (Virgilia divaricata) and an invasive (Acacia mearnsii) legume tree species in the CFR.


Trees were sampled by bark wounding (N=10 trees per spp, 6 localities, 120 trees total). These wounds where left open for six weeks (November-December 2012). After which, bark samples were collected and ophiostomatoid fungi isolated. Fungi were identified using molecular methods. Foliage associated arthropods were sampled using a vacuum sampler-D vac. Insects were sorted into morpho types, identified to order level and classed into feeding guilds.


Preliminary results show overlap in ophiostomatoid fungal associates. Ophiostoma quercus and Ophiostoma plurianulatum have been identified on both trees, but are not pathogenic. Ceratocystis species have been collected, however identification and pathogenicity tests is needed. Preliminary arthropod data show overlap of species on host plants with some exclusive to V. divaricata. Species -richness and -abundance are currently being assessed.


We find support for the potential exchange of pests and pathogens between a native and an invasive legume tree in the CFR. This is important as native forests in the CFR are isolated patches. A. mearnsii has a wide invasive range; it therefore provides a corridor for movement of pests and pathogens that have previously been isolated. These results can provide added incentive for clearing of IAPS as well as another parameter to consider when prioritizing areas for clearing.