Monitoring Phragmites australis biological control agent movement into the US

Description

Background:Phragmites australis (Cav.) Trin. Ex Steudel (common reed, Roseau cane) is a cosmopolitan wetland grass, native to Eurasia but widespread and damaging in North America. Although populations are seen in Europe as valuable and endangered habitats, P. australis is regarded as invasive and negatively impacts biodiversity in North America. Molecular studies have suggested that the spread of P. australis in recent decades in North America is due to an introduced population from Europe, which displaces native North American genotypes. Native North American populations of common reed were recently recognized as the subspecies, P. australis americanus, distinct from the European introduction, P. australis australis. Management tools have been developed for common reed control in the US, but so far the only targeted option is biological control. Investigations to evaluate the potential for classical biological control of the introduced genotype of common reed has been ongoing for more than 20 years. Two promising agents that have been developed by CABI- Switzerland are Archanara neurica and A. geminipuncta, both European stem-boring moths.An application for release of Archanara spp. as biological control agents of P. australis australis in the United States is currently under review by USDA APHIS. Until the permit is issued, agents will not be available for release in the US. However, Canadian authorities have approved the release of Archanara spp., and first releases were made along the northeastern shore of Lake Ontario in Fall 2019. A critical component of any management program, but especially biocontrol, is the measurement of pre-management conditions at sites to develop a baseline for comparison and determination of management efficacy. Thus, there is an urgent need to 1) identify potential release plots and survey Phragmites australis stands in the US Great Lakes for baseline measurement of infestation densities and extent, 2) document species diversity and presence of native and introduced Phragmites australis haplotypes, and 3) monitor for immigration of Archanara spp. from Canadian release locations. Monitoring should therefore occur primarily along the southern shore of Lake Ontario and possibly Lake Erie, given their proximities to Canadian releases.Brief Description of Anticipated Work:The objectives of the proposed effort include:Objective 1: Establish long-term Phragmites monitoring sites near the Canadian border on Lake Ontario (Ant. Year 1).Objective 2: Develop standardized monitoring protocols that can be used at any site by USACE or other personnel (Ant. Year 1).Objective 3: Monitor at established sites for arrival of Archanara spp. from Canada (Ant. Years 1-4)Description of proposed effort is as follows:Establish long-term Phragmites monitoring sites near the Canadian border on Lake Erie: Stands of European Phragmites australis australis should be identified that are in the vicinity of original Archanara release locations. Criteria for choosing sites will be discussed in coordination with ERDC. We anticipate up to 10 study sites to be established in coordination with the vendor.Develop standardized monitoring protocol that can be used at any infested site: To determine impacts of biological control agents once they are detected in P. australis stands, monitoring protocols should be developed. Protocols may include a method to assess presence of Archanara spp. adults and/or larvae; density, extent and health of Phragmites (both native and introduced subspecies) and identification of Phragmites haplotypes. For larval detection, winter surveys may be necessary. This will create important baseline information for long-term monitoring efforts and to document population-level changes in Phragmites abundance and associated impacts. The protocol should be standardized and easily transferrable to non-experts for use in a larger monitoring network within the Great Lakes region.Monitor at established sites for arrival of Archanara spp. from Canada: Once the protocol is developed and approved, monitoring should commence in order to record baseline data (described above) and detect Archanara spp. presence. This objective will likely be a multi-year effort because it is unclear whether 1) Archanara spp. are established at Canadian release sites, and 2) what their rate of dispersal from release sites will be.Site Location:This work will occur in the Great Lakes region, primarily in the vicinity of Archanara release sites near northeastern Lake Ontario. A portion of the effort (e.g., Phragmites stem dissections) may occur at the vendor’s laboratory. Phragmites australis australis is widespread in the Great Lakes, but sites will be identified during year 1. ERDC will largely rely on the vendor for site identification and establishment but will provide feedback on site selection, as needed.Public Benefit:These data will benefit the public by establishing pre-biological control conditions in Phragmites stands, and detecting migration of biological control agents Development of biological control is necessary to create a long-term self-sustaining control mechanism for beneficial uses of waterbodies, such as recreation, drinking water supply, and flora and fauna habitat, long after the initial program phases are complete.

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