Natural History Studies for the Preliminary Evaluation of Larinus filiformis (Coleoptera: Curculionidae) as a Prospective Biological Control Agent of Yellow Starthistle

We studied the life history, geographic distribution, behavior, and ecology of Larinus filiformis Petri (Coleoptera: Curculionidae) in its native range to determine whether it is worthy of further evaluation as a classical biological control agent of yellow starthistle, Centaurea solstitialis (Asteraceae: Cardueae). Larinus filiformis occurs in Armenia, Azerbaijan, Turkey, adults were well has been reared only from C. sobditiatis. At field sites it) central and eastern Turkey, adults were well synchronized with the plant, being active from mid-May to late July, and ovipositing ill capitula (flowerheads) of C. solstitialis from mid-june to Larvae destroy all the seeds ill a capitulum. The insect is univoltine in Turkey, and addults hibernate from mid-September to mid-May. In the spring, before adults begin ovipositing, they feed on the immature flower buds of C. solstitialis, causing them to die. The weevil destroyed 25-7.5% of capitula at natural field sites, depending on the sample date. Preliminary host specificity experiments oil adult feeding indicate that the weevil seems to be restricted to a relatively small number of plants within the Cardueae. Approximately 57% of larvae or pupae collected late in the summer were parasitized by hymenopterans [Bracon urinator, B. tshitssherini (Braconidae) and Exeristes roborator (Ichneumonidae), Aprostocetus sp. (Eulophidae), and unidentified species of Eurytomidae and Ormyridae]. This weevil may be a better choice than the other capitula insects already established in the United States, particularly in colder parts of the plant's range.