The contribution of biological control to the management of thistles
T.L. Woodburn and D.T. Briese, CSIRO Division of Entomology, Co-operative Research Centre for Weed Management Systems, GPO Box 1700, Canberra, ACT 2601, Australia.
CSIRO Division of Entomology has two major projects on the biological control of carduine thistles, one against nodding thistle (Carduus nutans) and another for scotch and Illyrian thistles (Onopordum acanthium and O. illyricum). The strategies for biological control of these target thistles are similar, although the agents used are different. Since thistle populations depend solely on seedling establishment for recruitment, the priority area in both projects is to limit seeding, with the ultimate aim to reduce the soil seed banks found in Australia to the much lower levels found in Europe. Both projects include insects that attack the capitula and thus have a direct impact on seeding; both also have insects that attack vegetative parts of the plant and thus indirectly limit seed production. The role of biological control in an overall management strategy for these two groups of thistles is briefly discussed.
Plant Protection Quarterly (1996) 11 (Supplement 2) 250-253.