ANTI-HERBIVORE MECHANISMS OF ECONOMICALLY IMPORTANT PROTEACEAE SPECIES IN THE AFRICAN-CAPE-FYNBOS

Five economically important species of the family Proteaceae were inve stigated to determine which leaf characteristics possibly contributed to deterring insect herbivory. The presence of phenolic compounds such as tannins in the leaves of all five plant species and the ability of these to precipitate proteins varied between the plant species. The y oung leaves of Leucadendron laureolum exhibited a pronounced cyanogeni c capacity, while those of Leucospermum cordifolium and Protea neriifo lia were covered by a thick layer of trichomes. The glabrous young lea ves of P. repens and P. cynaroides were apparently protected by phenol ic compounds. The increasingly sclerophyllous character of ageing prot eaceous leaves may afford these leaves some protection against certain insects. The importance of these findings is discussed in terms of th e development of insect resistant Proteaceae cultivars.