Insect agents used for the biological control of Australian Acacia speciesand Paraserianthes lophantha (Willd.) Nielsen (Fabaceae) in South Africa

Several Australian Acacia species and the closely related Paraserianthes lo phantha (Willd.) Nielsen invade agricultural lands, conservation areas, wat ercourses and catchments in South Africa. The biological control programmes against th is suite of weeds in South Africa have been restrained by confl icts of interest and by the poor dispersal and slow population growth of mo st of the introduced insect biocontrol agents. Nevertheless, all of the ins ects that have been released have become established on their respective we ed species and, in most cases, evaluation studies indicate that the populat ions are increasing and spreading. In this paper, progress over the last 10 years (1989-1999) with five seed-feeding Melanterius species (Curculionida e) and two Trichilogaster species (Pteromalidae), is reviewed.