2010 Annual Report 1a.Objectives (from AD-416) Test host plant specificity of Larinus filiformis in quarantine laboratory and field experiments in order to submit a petition to USDA-APHIS requesting permission to release it as a biological control agent of yellow starthistle. 1b.Approach (from AD-416) We will conduct choice and no-choice oviposition experiments on the flower head weevil Larinus filiformis in our quarantine laboratory and conduct a field host specificity evaluation of L. filiformis in its native range in Turkey. If it is sufficiently host-specific, we will submit a petition to USDA-APHIS to obtain a permit to release the weevil. Documents Reimbursable with US Forest Service. Log 41839. 3.Progress Report Larinus filiformis, a prospective biological control agent of yellow starthistle, was collected at two sites in Turkey and 91 adults were sent to the USDA-ARS quarantine laboratory in Albany, CA. Host specificity tests were initiated, but all adults died before results could be obtained. Cadavers are being evaluated for the presence of pathogens that may have caused the mortality. Field sites have been selected for the 2011 field evaluation of host specificity and biennial plants have been started.