2007 Annual Report 1a.Objectives (from AD-416) To study the natural occurrence of chalkbrood pathogens and the associated host-pathogen interactions, and to utilize this knowledge to improve disease control in social and solitary bees. 1b.Approach (from AD-416) The co-operator will host Rosalind James to visit for approximately four weeks in 2007. Travel expenses for these visits will be funded by the co-operator. These visits will facilitate the collection of Ascosphaera species in their native range, and in bees that occur in Denmark. Comparative DNA analyses will be used determine the origin of Ascosphaera that occur in the U.S., to determine which species are native to North America, and which are accidental introductions. R. James will also help direct a PhD student who will study chalkbrood disease in bees, and some of that research will be conducted in Logan, UT. The collaborator and associates will develop methods for diagnosing Ascosphaera infections in bees, and determine the genetics of host resistance to infection. 3.Progress Report This report serves to document research conducted under an international non-funded cooperative agreement between ARS and the University of Copenhagen. Additional details of the research can be found in the report for the parent project 5428-21000-010-00D Pollinating-Insect Biology, Management, and Systematics Research. This year, one SY visited the Royal Veterinary and Agricultural University (KVL) in Copenhagen, Denmark to establish cooperative research on chalkbrood disease in bees. Chalkbrood is caused by fungi in the genus Ascosphaera, and most of the initial identifications for the Ascosphaera were made in Denmark during the 1970’s. We initiated a study to develop methods for long-term storage of Ascosphaera cultures to enhance our ability to study different species and strains of these fungi. These studies are still underway, but only methods for storing spores have so far been successfully repeated. In addition, the KVL has sponsored a new PhD student to conduct studies on chalkbrood in honey bees, and this student will conduct her research as part of this collaboration. A second student has also been identified and will start her program of study next year. ADODR monitoring activities included phone calls, conference calls, on-site visits, and e-mails.