1. Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
2. Department of Zoology and Entomology, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa
3. Agricultural Research Council, Plant Health and Protection, PO Box 1055, Hilton, 3245, South Africa
4. Centre for Biological Control, Rhodes University, Makhanda, 6140 South Africa