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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Research Project #445029

Research Project: Discovery and Pre-Release Evaluation of Weed Biocontrol Agents

Location: Invasive Species and Pollinator Health

Project Number: 2030-22000-033-022-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: May 1, 2023
End Date: Jun 30, 2026

The primary objectives of the research covered in this agreement are to 1) Determine whether Aculodes altamurgiensis infestation significantly reduces germination of medusahead seeds; 2) Conduct host-range studies of A. altamurgiensis; 3) Survey native ranges of targeted annual grasses for new populations of known candidate biocontrol agents to establish laboratory colonies for biologcial studies; 4) Survey native ranges of targeted annual grasses for discovery of new candidate agents.

1) Colonies of A. altamurgiensis; will be reared on medusahead plants in a greenhouse. Control plants will be sown from seed, grown in a different greenhouse, and inspected regularly to ensure the absence of mites or other natural enemies. Following plant senescence and seed dehiscence, all seeds produced by each plant will be harvested and the number of seeds produced by each plant will be recorded. Seeds will be allowed to dry and will then be tested for germination. Germination rate data will be analyzed to detect differences between infested and control plants. 2) Medusahead plants will be grown, along with plants of non-target grass species. All test plants will be exposed to A. altamurgiensis under choice conditions, i.e. different species, including medusahead, will be exposed together; and no-choice conditions, i.e. mites are exposed to each test plant species individually. Two to four weeks following mite infestation, plants will be dissected and mites will be counted from each plant to determine if mite colonies increased or decreased during the test period. 3) Marked annual grass populations will be surveyed using sweep nets, observation, collection and dissection, among other methods, depending on the candidate agent(s) being sought. Collected arthropods will be returned to the laboratory and placed on their host species for rearing and establishment of colonies for pre-release testing. 4) New populations of targeted annual grass species will be sought and inspected for the presence of natural enemies by various means, including sweep netting, field inspection, and collection of target plants for laboratory dissection and emergence of insects in the laboratory. Recovered arthropods will be morphologically and genetically identified and prepared for biological and host-range testing.