Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 18, 2006
Publication Date: January 1, 2007
Citation: Smith, L. 2007. Physiological host range of Ceratapion basicorne, a prospective biological control agent of Centaurea solstitialis (Asteraceae). Biological Control. 41:120-133 Interpretive Summary: Yellow starthistle is an alien weed that has invaded about 20 million acres in the western U.S. It is especially abundant in Pacific western states. The spiny plant interferes with grazing livestock and outdoors recreation, it is fatally poisonous to horses, and it outcompetes desirable vegetation. Six species of insects have been introduced as biological control agents, but they are not providing sufficient control. Foreign exploration in the Mediterranean Basin indicates that the weevil, Ceratapion basicorne, could be an important biological control agent. We conducted host plant specificity studies in a quarantine laboratory to determine if this insect would be safe to use as a biological control agent of yellow starthistle. Successful development of a biological control program would permanently reduce populations of this weed, which will reduce herbicide use, increase value of rangeland and recreational wildlands.
Technical Abstract: Ceratapion basicorne (Coleoptera: Apionidae) is a weevil native to Europe and western Asia has been proposed as a prospective classical biological control agent of yellow starthistle (Centaurea solstitialis), which is an important invasive alien weed in the western United States. Host plant specificity of the insect was evaluated in no-choice oviposition experiments. Feeding on leaf tissue by adult females was highly correlated to oviposition rate, both of which occurred primarily on plants in the tribe Cardueae (thistles), and especially those in the monophyletic subtribe Centaureinae. The highest rates of larval development occurred on yellow starthistle and bachelor's button (Ce. cyanus, garden cornflower), and there was significant development on Napa starthistle (Ce. melitensis, tocalote), blessed thistle (Cnicus benedictus), safflower (Carthamus tinctorius), and common crupina (Crupina vulgaris). All the plants that supported some larval development are within a monophyletic clade within the Centaureinae. No native North American plants appear to be at risk of significant damage by this insect. Additional testing of safflower and bachelor's button under choice conditions should complement these results to help determine the degree to which these plants are at risk.