Population structure and possible origin of Amylostereum areolatum in South Africa

The woodwasp, Sirex noctilio, and its symbiotic fungus, Amylostereum areola tum, cause extensive damage to pine plantations in the Southern Hemisphere. S. noctilio was first reported from South Africa in 1994. In this study th e population diversity of A. areolatum isolates from South Africa, South Am erica, Australasia and Europe was determined by vegetative incompatibility testing. All 108 South African and 26 South American isolates belonged to t he same vegetative compatibility group (VCG). This VCG showed a weak incomp atibility reaction with the single Tasmanian and single New Zealand isolate s tested. This VCG differed from VCGs from Europe. It also differed from is olates associated with the biocontrol nematode, Deladenus siricidicola, whi ch is produced in Australia. It is concluded that the South African and Sou th American populations of A. areolatum share a common origin.