Host specificity of Bangasternus orientalis Capiomont (Coleoptera : Curculionidae) introduced into the United States for biological control of yellowstarthistle (Centaurea solstitialis L., Asteraceae : Carduae)

The weevil Bangasternus orientalis Capiomont was selected as a candidate fo r the biological control of Centaurea solstitialis L. (yellow starthistle) in the United States. Its potential host range was studied during 1982, 198 3, and 1984 in Rome, Italy, using populations collected from C. solstitiali s in Thermi near Thessaloniki and Kozani in northern Greece. Adults laid eg gs only on members of the genus Centaurea and the thistle Onopordum acanthi um; eggs laid on O. acanthium hatched but Ist instars died before entering buds. There was no significant difference in the number of eggs laid on var ious U.S. and Italian strains of C. solstitialis included in the tests. Egg s were not deposited on plant species of economic importance such as Cynara scolymus, Helianthus annuus, Carthamus tinctorius, and Lactuca sativa. Lar vae completed their larval development only on C. solstitialis from Greece and on U. S. and Italian populations of C. solstitialis among the 60 plant species, varieties, and strains (in 7 families) tested. This restricted hos t range suggested introduction of this weevil as a biological control agent against yellow starthistle in the United States. Releases of B. orientalis were made in California, Washington, Idaho, and Oregon in 1985 and it beca me established in all states in 1989.