Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2008
Publication Date: 12/17/2008
Citation: Mkize, N., Hoelmer, K.A., Villet, M. 2008. A survey of fruit-feeding insects and their parasitoids occurring on wild olives, Olea europaea ssp. cuspidata, in the Eastern Cape of South Africa. Biocontrol Science and Technology. 18:991-1004.
Interpretive Summary: There is a small but well-developed commercial olive industry in the Republic of South Africa, based mostly in Western Cape Province, but which has recently been expanding into East Cape Province. The pest status of olive fruit fly, a primary pest worldwide of olives, and other potential fruit pests was surveyed in the East Cape by collecting fruits of cultivated and wild olives during 2003-2005, recording levels of pest infestation, and documenting the parasitic wasps associated with them. Two fruit fly species, the olive fruit fly and a related species, Bactrocera biguttula, constituted the majority of fruit pests found, but they infested only a small proportion of total fruit. Seed wasps also infested a small proportion of fruits. Four species of parasitic wasps attacked the olive fly in this region. The results suggest that fruit flies are not economic pests in the Eastern Cape and the small numbers present may be controlled to a considerable level by their natural enemies. These parasitic wasps may also prove to be useful as biological control agents of olive flies in other parts of the world.
Technical Abstract: Fruits of cultivated olives, O. e. europaea, and wild olives, O. e. cuspidata, were collected at nine locations in the Eastern Cape, South Africa, in 2003-2005 to investigate levels of pest infestation and to determine the parasitoids associated with them. Three species of Tephritidae (olive fruit fly, Bactrocera oleae, B. biguttula and Mediterranean fruit fly, Ceratitis capitata) and one of Drosophilidae (Drosophila melanogaster) were obtained. Braconid wasps of the subfamilies Opiinae (Psyttalia lounsburyi, P. concolor, Utetes africanus) and Braconinae (Bracon celer) were reared from fruits containing B. oleae and B. biguttula. The percentage parasitism was as low as 6% and reached 77% in some areas. No parasitoids were obtained from C. capitata or D. melanogaster. A variety of chalcidoid wasps were collected, including Eurytoma oleae and Sycophila sp. (Eurytomidae), Ormyrus sp. (Ormyridae), and Eupelmus afer and E. spermophilus (Eupelmidae). Only one species of moth, Palpita unionalis (Crambidae), was recovered but in very low numbers and without parasitoids. Results from a single collection of green and ripe olive fruit from the Western Cape were also reported. The results suggest that fruit flies are not economic pests in the Eastern Cape and the small numbers present may be controlled to a considerable level by their natural enemies.