Biological Control of Yellow Starthistle: New prospects for an old problem Lincoln Smith1, Massimo Cristofaro2, Michael Pitcairn3, William Bruckart4, Dale Woods3, Timothy Widmer5, Dana Berner4, Allison Drew1, 1USDA-ARS, Albany, CA; 2ENEA, Rome, Italy; 3CDFA, Sacramento, CA; 4USDA-ARS, Ft. Detrick MD; 5USDA-ARS-EBCL Montpellier, France ([email protected])

Six species of biological control agents have been introduced to control yellow starthistle. All six attack the seedheads. The most widespread agents are the Yellow Starthistle is an annual that reproduces and Rust pathogen (Puccinia jaceae var. Flea (Psylliodes sp. nr. Yellow starthistle (YST) is false peacock ( succinea) and the hairy weevil (Eustenopus villosus). spreads only by seed. Because the seedhead seemed a solstitialis) first released July 2003 chalcomera) from s. Russia an alien plant that probably Though the agents have established throughout California, their efficacy is not yet promising target, all previously-released biological control originated in the eastern known. agents were seedhead-feeding . Several by CDFA and ARS scientists Mediterranean. It was first introduced insects are now widespread; however, they collected in California in 1869, have not reduced plant densities to acceptable levels at and now infests 42% of the most locations. A new agent, a rust pathogen, was first state’s townships. It released in July 2003. Foreign exploration has been diminishes the value of expanded in and southern Russia to search for rangeland for grazing and Urophora Bangasternus Chaetorellia Eustenopus curtus new agents that attack other parts of the plant. New recreation, elevates the risk of sirunaseva orientalis succinea villosus prospects include several newly described species. Two wildfire displaces native new agents are being evaluated at the Albany quarantine species, and is toxic to horses. Status of Biological Control Agents facility to insure that they will be both safe and effective. Biological Common name First Status Other agents are being evaluated by our overseas This weed is much less invasive in its land of origin, control agent release B. Bruckart (USDA-ARS, Frederick, MD) Urophora 1969 Never established in USA. collaborators. The diversity of prospective agents greatly presumably because natural enemies, such as insects, plant jaculata and D. Woods (CDFA) Urophora YST1 gall fly 1984 W idely established, present at most YST increases our chances of finding some that are suitably diseases, or competing plants, help to keep it under sirunaseva infestations in C A & O R; a few sites in W A, ID . New cryptic species discovered; Bangasternus YST bud weevil 1985 W idespread in CA, OR, W A & ID. host specific and sufficiently damaging to reduce yellow natural control. We are exploring for insects and pathogens orientalis 20 experimental field releases in 2004. passed preliminary host specificity tests; Chaetorellia YST peacock fly 1988 Prefers bachelor button; established at a few starthistle populations to innocuous levels in the U.S. that attack this plant. Prospective agents are tested for host australis sites in C A; widespread in O R, W A, ID . additional testing underway. Eustenopus YST hairy weevil 1990 W ell established in CA; widespread in OR, W A; specificity to make sure they do not attack other plants. After villo sus a few sites in ID, UT. Very abundant. M. Cristofaro (ENEA, Rome, Italy), M. Dolgovskaya Larinus curtus YST flower weevil 1992 Established at a few sites in CA, W A, ID; (Russian Academy of Sciences, St. Petersburg), and widespread in O R . evaluation and approval by state and federal agencies, these Unapproved accidental introduction: P. Audisio (U. Rome, Italy) Chaetorellia YST false 1991 W idely established in CA & OR, and spreading Root crown weevil (Ceratapion basicorne) from agents will be released to try to reestablish the natural control succinea peacock fly into W A, ID & NV. Has been evaluated for that occurs in the land of origin. nontarget impacts. Very abundant. Turkey develops in rosette 1 Y S T = yellow sta rthistle Several other prospective agents are in early stages of Testing safety for nontarget evaluation, including a blister mite, a rosette fly, a lace bug, Distribution of Yellow Starthistle Distribution of plants in quarantine lab and a seedhead weevil, and five fungal pathogens. Eustenopus villosus foreign field tests has Spread of Yellow Starthistle in the shown it to be safe with respect to crops such as Blister mite, Aceria solstitialis, from Rosette fly, Lace bug, Tingis Pacific Northwest Turkey. Botanophila grisea, from Survey for artichoke and and Newly described species likely to be very turcica, from Turkey. Eustenopus to related native species. host-specific. . Known only from yellow villosus Preliminary tests conducted by J. Larvae attack rosette buds starthistle. Littlefield (Montana State U., Bozeman). during winter. Preliminary studies by December 2002 Preliminary studies by J. M. Cristofaro (BBCA, This weevil Kashefi (ARS, Greece) Italy). and B. Rector (USDA- Many is abundant ARS, France).

No. of larvae can in the field,

counties Seedhead weevil, Plant pathogens being develop in attacking up Larinus evaluated: to 100% of Phoma exigua, one root filiformis, Synchytrium solstitiale, plants at a from Turkey. Streptomyces griseus, Year Very abundant & active Cladosporium herbarium, Cercosporella INVADERS Database System, http://invader.dbs.umt.edu site. in late season. sp. L. Gültekin (Ataturk U., T. Widmer (USDA-ARS, France), CDFA, http://www.cdfa/ca/gov/phpps/ipc/biocontrol/ L. Smith (ARS, Albany, CA), M. Cristofaro (ENEA, Italy), R. Hayat (Ataturk U., Turkey), B. Rector (ARS, France). Turkey). D. Berner (USDA-ARS, Ft. Detrick)