2010 Annual Report 1a.Objectives (from AD-416) The goal of this project is to isolate and characterize strains of fungi (Ambrosiella spp.) associated with ambrosia beetles. Objectives include. 1)Isolate strains of Ambrosiella from ambrosia beetles (Xylosandrus spp.),. 2)Develop molecular characterization of these strains, and. 3)Determine their susceptibility to commercially available fungal antagonists. 1b.Approach (from AD-416) Ambrosia beetles (Xylosandrus spp. and others) are pests of a wide array of woody plants used in the nursery industry. They depend for their survival on their own cultivation of a fungus (Ambrosiella spp. and others). Fungi will be isolated from available Xylosandrus spp., including X. crassiusculus and X. germanus. RAPD-based techniques and others will be used to characterize strains genetically. Each strain will be tested for susceptibility to commercially available fungal antagonists, including Trichoderma spp. and others. Survival of Ambrosiella spp. and beetles within galleries will be evaluated. 3.Progress Report 1. Ambrosia fungi were isolated from field-collected X. germanus and X. crassiusculus adult females from OH, TN and VA in late spring to early summer. Thirty-seven new fungal isolates were obtained from the former and forty-four isolates from the latter. All samples are maintained at the USDA-ARS in Ithaca, NY. Molecular characterization studies will continue this fall. 2. In vitro mycelial competition assays were conducted between three representative Ambrosiella spp. fungi from X. germanus and X. crassiusculus against commercially available fungal biocontrol agents Beauveria bassiana and Metarhizium anisopliae. Assays were developed to determine differential competition, primary resource capture and secondary resource capture. Our results show that either biocontrol fungus had a negative effect on the growth and spread of ambrosia fungi. Monitoring was done through weekly meetings and periodic written summaries.