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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Research Project #435099

Research Project: Release and Evaluation of Biocontrol Agents of Weeds as Part of Areawide Weed Management in the Sacramento-San Joaquin Delta

Location: Invasive Species and Pollinator Health

Project Number: 2030-22300-032-006-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 1, 2018
End Date: Aug 31, 2021

To collaboratively pursue the objectives of the Delta Region Areawide Aquatic Weed Project (DRAAWP) by providing technical support to determine the outcome of releases of three biological control agents of water hyacinth (water hyacinth planthopper, moth, and weevil) and two biological control agents of arundo (arundo wasp and armored scale). To conduct releases and follow-up monitoring to determine establishment of biocontrol agents and impact on targeted weeds.

The water hyacinth planthopper Megamelus scutellaris, the water hyacinth moth Niphograpta albiguttalis, and the water hyacinth weevil Neochetina eichhorniae will be reared at the USDA, Agricultural Research Service (ARS) lab in Albany, California. These agents will be released at up to 24 sites, five release plots per site, in the Sacramento-San Joaquin Delta using boats and from land. Release sites will be monitored every 1 to 2 months for up to two years. Release plots will be examined to determine density of insects and size of live plants. Water quality will be measured as concentrations of nitrate, ammonium, and phosphate as well as pH and salinity, and related to success of biocontrol agent establishment Predators of water hyacinth biological control agents will also be assessed by determining density. Some plants will be dissected in the lab to quantify degree of biocontrol agent damage. The arundo waso Tetramesa romana, and the arundo armored scale, Rhizaspidiotus donacis, will be released at up to 10 sites, five plots per site, in the Delta, at sites accessible from land. Release plots will be pre-treated with mechanical topping of arundo shoots, followed by release of biocontrol agents one month later. Plots will be monitored every two months to determine density of insects. Plots will be examined one and two years post-release to determine impact, by counting live shoots and measuring shoot biomass. Some shoots will be dissected to determine density of arundo wasps and armored scales and to determine if parasites of either agent are present. Biological control releases on both water hyacinth and arundo will be coordinated with chemical and mechanical control of these weeds in an integrated, adaptive management framework for protection of water resources.