n African Entomology - The spread of Fabricius (Hymenoptera : Siricidae) in South African pine plantations and the introduction and establishment of its biological control agents




Within eight years of its discovery in the Cape Peninsula in 1994, the Eurasian woodwasp, , has spread up to 380 km along both the western and southern coasts of South Africa. A biological control programme was begun within the first year with the importation of the Kamona strain of the parasitic nematode, , which had originally been imported into Australia from Hungary. In 1995 and 1996 a total of 70 million nematodes were imported and inoculated into 296 -infested trees in a 90km arc around Cape Town. The parasitism rate increased from 22.6% in 1996, to 54% in 1997, and 96.1% in 1998. The early larval parasitoid, , was imported into South Africa in 1998 from Uruguay, where it had arrived with its host. A total of 456 parasitoids was released in plantations from Cape Town to Riversdale from 1998-2001. By 2002 it was confirmed to be established at Stellenbosch. , a late larval parasitoid originally from North America, was imported from Australia into South Africa in 1998 and 38 mated females were released on the Gifberg overlooking Vanrhynsdorp a year later. No recoveries from this site have been made and it is unknown whether it has become established. Since 1994, the numbers of the European cerambycid, , had increased because they were able to breed in the lower trunk of trees killed by . Their numbers have since declined with those of following the introduction of the natural enemies. At no stage did the loss of trees exceed 3.2% of a compartment and effective biological control was achieved during this period within the southwestern Cape.


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