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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Research Project #439611

Research Project: Biological Control of Invasive Plants in the Western USA

Location: Invasive Species and Pollinator Health

Project Number: 2030-22000-033-006-I
Project Type: Interagency Reimbursable Agreement

Start Date: Oct 1, 2021
End Date: Sep 30, 2026

1) Expedite the open field tests of two candidate weevils that attack yellow starthistle and Onoportum in Bulgaria. 2) Discovery of candidate biocontrol agents of Chondrilla juncea. 3) Domestic pre-release demographic data for the biocontrol targets Russian olive (Elaeagnus angustifolia) and hoary cress (Lepidium draba).

1) Conduct open field choice test at the University field station, very close to the University of Plovdiv, Central Bulgaria. The test will be done with two seed feeder weevils: Larinus filiformis and Larinus latus. Twelve test plant species (including the controls) distributed in 10 rows will be sown or transferred from pots into the soil in two different periods: the late summer 2021 and the spring 2022; weevils will be collected in Central Bulgaria two times, at the beginning and at the end of June. After each release, the field plot will be covered with a large screen cage for 10 days, in order to confine the weevils in the plot, avoiding their dispersal. After 10 days (each time), the light screen cage will be removed, in order to allow the weevils to disperse. As soon as the flowerheads will be mature, they will be harvested and kept separated from the others (recording date and plant species and position). All the material that will emerge from the capitula will be kept for morphological and genetic analysis. 2) Field explorations will be carried out in Greece, Armenia, Bulgaria, Romania, Serbia and Slovakia to collect natural enemies associated with the target weed (Chondrilla juncea). Among the most promising new candidate agents, special emphasis will be done to perform life history observations and preliminary host range studies on 2 defoliator insects (the noctuid moth Simyra nervosa and an undetermined sawfly) and one seed feeder noctuid moth (Schinia cognata). Additional efforts will be given to search for other candidate agents. 3) Maintain and collect data from common gardens, experimental introductions, and extensive field surveys to provide long-term demographic data for these projections and provide baseline infrastructure to evaluate post-release impacts. ARS has adopted this approach for Russian olive (Elaeagnus angustifolia) and hoary cress (Lepidium draba); this includes experimental introductions, reciprocal transplant common gardens, demographic surveys, and pollination studies targeted toward quantifying vital rates and herbivore impacts.