The potential of a pre-introductory survey on Arundo donax (L.) to guide a biological control program in South Africa

The potential of a pre-introductory survey on Arundo donax (L.) to guide a biological control program in South Africa
Kim CANAVAN, Iain D. Paterson, Martin P. Hill
Biological Control Research Group, Department of Zoology & Entomology, Rhodes University, Grahamstown 6140, South Africa

A pre-introductory survey is a method used to assess an invasive alien plant in its adventive range in order to gain information on the status of the species prior to the establishment of a biological control program. This study investigated the invasive alien reed Arundo donax (L.) in South Africa prior to the release of biological control agents. The genetic structure of A. donax populations in South Africa, as well as the herbivores associated with the plant, were investigated. Genetic structure was investigated by sequencing three regions of the chloroplast and combining this information with four microsatellite regions. From this it was determined that all populations of A. donax in South Africa are haplotype M1; the most widely distributed haplotype worldwide believed to originate from the Arabian Peninsula. In addition, no genetic diversity was found, indicating that reed stands in South Africa are essential one clone. The diversity of herbivores associated with this haplotype were then recorded. Seven herbivores were recorded feeding on A. donax with two of these species having been introduced from the host plant’s native distribution. A potential biological control agent, the monophagous gall-forming Tetramesa romana Walker (Hymenoptera: Eurytomidae), was found to already be established at all sites investigated in this study. Overall the study was able to determine the region of origin of South African A. donax and record all known herbivores already established in the adventive range. This information will play an important role in guiding the future biological control programme.