REAPPRAISING THE POTENTIAL OF BIOLOGICAL-CONTROL AGAINST THE WEED CARTHAMUS-LANATUS

Carthamus lanatus L. (Compositae, saffron thistle) is a major weed of worldwide distribution that originated in southern Europe. Surveys, re arings, tests of specificity, and in-depth field studies undertaken be tween 1990 and 1995 have considerably improved our understanding of th e complex of natural enemies associated with C. lanatus in its native range. The root-feeding fly, Botanophila turcica Hennig (Dipt.: Anthom yiidae) is herewith recorded for the first time from C. lanatus; the r osette rust fungus, Puccinia sommieriana Saccardo (Basid.: Pucciniacea e) is reported for the first time from C. lanatus in Greece; the flowe rhead fly, Urophora mauritanica Macquart (Dipt.: Tephritidae) is shown to concentrate its attacks on C. lanatus in the field in presence of the closely related Carthamus tinctorius L. (cultivated safflower). Ac cording to site and year the direct mortality caused by each of these three organisms to populations of C. lanatus fluctuated between 10 and 50%. In addition, each of them had a whole range of indirect effects of some importance on C. lanatus populations, all of which were also c umulative. Strong phenological (in the case of B. turcica), and practi cal evidence (field records, plus results of host specificity tests) a re presented, and discussed which document the fact that the three phy tophagous species may be considered as specifically attacking C. lanat us, but without damaging field crops of its close relative, C. tinctor ius. Contrary to traditional belief, biological control may therefore be considered a promising, safe approach for reducing C. lanatus popul ations.