Project Abstract For the Project Ending June 30, 2019 PROJECT TITLE: Biological Control of Canada Thistle PROJECT MANAGER: Roger Becker AFFILIATION: Department of Agronomy and Plant Genetics, University of Minnesota MAILING ADDRESS: 411 Borlaug Hall, 1991 Upper Buford Circle CITY/STATE/ZIP: St. Paul, MN 55108 PHONE: 612-625-5753 E-MAIL:
[email protected] WEBSITE: https://appliedweeds.cfans.umn.edu FUNDING SOURCE: Environment and Natural Resources Trust Fund LEGAL CITATION: M.L. 2015, Chp. 76, Sec. 2, Subd. 06c APPROPRIATION AMOUNT: $300,000 AMOUNT SPENT: $300,000 AMOUNT REMAINING: $0 Overall Project Outcome and Results Canada thistle is a serious threat to natural and managed ecosystems in Minnesota. In 1998, the Canada thistle biocontrol stem-mining weevil Hadroplontus litura was introduced into a limited area in Minnesota with a resulting decline in Canada thistle populations. Although showing a preference for Canada thistle, initial host range testing of H. litura revealed that it attacked other native thistles. Before continuing biocontrol efforts with additional H. litura releases in Minnesota, we wanted to clarify whether H. litura would attack thistles native to Minnesota. The two objectives of our research were: 1.) determine whether H. litura could feed, oviposit and complete development on native thistles, and 2.) determine the phenology of native thistles in relation to Canada thistle. In no-choice tests, female H. litura accepted all native thistle species for oviposition and was able to complete development to the adult stage on swamp, field, tall, Flodman’s and wavy-leaved thistle. In Hill’s and the federally threatened Pitcher’s thistle, no adults were found in development tests.