Submitted to: International Symposium on Biological Control of Arthropods
Publication Type: Proceedings
Publication Acceptance Date: 2/14/2005
Publication Date: 9/12/2005
Citation: Hoelmer, K.A., Kirk, A., Pickett, C.H. 2005. Diversity and ecology of natural enemies of olive fly, Bactrocera oleae, in South Africa. International Symposium on Biological Control of Arthropods. p. 110.
Technical Abstract: The recent establishment in North America of olive fruit fly, Bactrocera oleae (Gmel.) (Diptera: Tephritidae), has renewed interest in classical biological control of this pest. Previous surveys conducted in Africa and Asia during the 20th century demonstrated a greater natural enemy diversity in southern and eastern Africa than in the Mediterranean region, but comprehensive evaluations were not conducted, and all attempted introductions were unsuccessful. To identify new natural enemies of olive fly for efficacy and specificity evaluation and possible importation into California, a new exploration program was conducted to survey wild olives, Olea europaea subsp. cuspidata, in both East and West Cape Provinces (Rep. South Africa) during the southern hemisphere fall seasons of 2001-2004, in the NE provinces (vicinity of Pretoria) in 2003, and also in Namibia in 2004. Surveys have also been conducted in Kenya and Pakistan. Olive fly populations were consistently higher in West Cape than in East Cape Province, as were populations of their natural enemies. Several braconids (Bracon, Psyttalia and Utetes spp.) were the most abundant parasitoids of the fly recovered in these surveys in southern Africa. The parasitoid fauna of southern Africa was similar to that found in Kenya but much richer than the diversity known from North Africa. Only one species of braconid, Psyttalia c.f. ponerophaga, has thus far been reared from olives in Pakistan. Numerous chalcidoids were also reared from wild olive in Africa, but they do not appear to be as abundant or widespread as the braconid species, and many are associated with seed chalcids attacking olives. Although wild olive is widely distributed across southern and eastern Africa, rainfall patterns may influence the occurrence and abundance of fruit, and consequently the abundance of flies and their parasitoids.