Progress 06/01/04 to 05/31/09
Outputs
OUTPUTS: We carried out surveys of existing natural enemies of invasive knotweed species at 67 sites scattered throughout the Pacific Northwest. At each site, we documented the species and families of insect herbivores using knotweed as a host, and the degree of damage caused by these insects. We compared the natural enemy communities among the different knotweed species. We compared the natural enemies found on the knotweed species in the Pacific Northwest with those reported from the East Coast of the U.S. and Alaska and to insects found feeding on knotweeds in Asia. We identified a number of potential future biocontrol release sites. We developed a list of plants to be tested and submitted a proposal report to the Technical Advisory Group on Biological Control of Weeds. We initiated host specificity testing on 4 species of candidate biological control agents imported from Japan. Results of this study were reported at various public meetings including the annual meetings of the Washington State and Oregon State Knotweed Working Groups. A technical report was written and published by the USFS Forest Health Technology Enterprise Team. PARTICIPANTS: Individuals: 1. Fritzi Grevstad (P.I.) University of Washington. 2. Paolo Sanguankeo, University of Washington. Partner Organizations: 1. University of Washington. 2. USDA Forest Service, Forest Health Technology Enterprise Team. 3. Oregon Department of Agriculture. 4. Washington State Department of Agriculture. 5. Oregon State University. 6. CABI Europe UK. 7. Agriculture and Agrifood Canada. Collaborators and Contacts: 1. Jim McIver, Eastern Oregon Agricultural Research Center, Oregon State University. 2. Richard Reardon, USDA Forest Service, Forest Health Technology Enterprise Team. 3. Richard Shaw, CABI Europe UK. 4. Robert Bourchier, Agriculture and Agrifood Canada. 5. Eric Coombs, Oregon Department of Agriculture. 6. Peter McEvoy, Oregon State University. 7. Darrell Ross, Oregon State University. 8. Suguro Ohno, Okinawa Prefecture Agricultural Research Center. Training and professional development was provided one research technician to learn about methods in biological control host specificity testing. TARGET AUDIENCES: Target audiences include land managers, county and state agencies, other scientists, other regions and countries that have invasive knotweed as an environmental problem. PROJECT MODIFICATIONS: After completing the initial objectives, we initiated host specificity testing for candidate biocontrol insects imported from Japan. This required renting a quarantine facility located at Oregon State University in Corvallis, Oregon and travelling to Japan to collect insects and import insects.
Impacts
We collected a total of 765 herbivorous invertebrates, comprising 23 families and 10 orders, from knotweed plants in the Pacific Northwest, including 17 species that appeared to be capable of both feeding and developing on the plant. We did not find any root feeders, stem borers, or flower feeders, nor did we find any insects that were specialists on knotweed. Insects rarely caused damage to knotweed. The results of the surveys indicate that the invasion by knotweed is not limited by herbivory and that the introduction of additional, specialist natural enemies could be beneficial in helping to control this invasive plant. We were able to determine that two of the four candidate biocontrol insects were not sufficiently host specific to consider as biological control agents. The other two insect species required additional testing, but to date appear to be host specific to the target weeds.
Publications
- McIver, J. and F. Grevstad. 2010. Natural enemies of invasive knotweeds in the Pacific Northwest. USDA Forest Service, Forest Health Technology Enterprise Team, 39 pp.
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Progress 10/01/06 to 10/01/07
Outputs
OUTPUTS: Arrangements and preparations were made to use the Richardson Hall Quarantine Facility at Oregon State University, which has enabled us to study and test exotic insects prior to being approved for release into the environment. The project investigator traveled as part of an international team of scientists to Japan, which is the native range of knotweeds, to carry out surveys and collection of candidate biocontrol agents. Sixty-one sites were surveyed and 3 insect species were collected and imported. These include the chrysomelid beetle Gallerucida bifasciata, the psyllid Aphalara itadori, and the moth Ostrinia ovalipennis. Preliminary host specificity tests were carried out on these insects using native and economically important plants related to knotweeds. A list of native and economically important North American plants was compiled following the guidelines of the Technical Advisory Group on Biological Control of Weeds. The list includes 68 species, primarily in the
family Polygonaceae. A majority of these plants have been collected and are currently being grown in a greenhouse. Initially, these plants were grown at the Oregon Department of Agriculture greenhouse in Salem, but were subsequently moved to a greenhouse in Corvallis, Oregon. Preliminary testing of the 3 biocontrol agents has been carried out on a subset of the test plants. For A. itadori, oviposition rates and nymph survival were measured in a "no-choice" situation in which the insects were caged onto individual test plants (6 replicates per species) and onto the target weed as a control. Ostrinia latipennis was also tested in a no-choice situation for the ability of larvae to feed and develop. Our laboratory colony of G. bifasciata was inconsistent in its reproduction, making it difficult to carry out development tests. Instead we carried out initial adult feeding trials in a situation in which the insects were offered a choice of host plants. We are currently working with a Chinese
collaborator to test larval development using field collected insects which are consistent in the reproduction. This research has been disseminated to communities of interest through presentations at the following meetings: Oregon Interagency Noxious Weed Meeting, Oregon Knotweed Working Group Annual Meeting, the Annual Meeting of the Weed Science Society, and a Northeastern States Knotweed Working Group Conference. Regular updates have been provided to staff of the Washington State University Extension and Oregon State University Extension, as the Oregon and Washington Departments of Agriculture. A brochure outlining the progress and needs of the project has also been produced and is currently being distributed.
PARTICIPANTS: Richard Reardon, USFS sponsor. Provided funding, program development. James McIver, Eastern Oregon Agriculture Research Center. Carried out field surveys in Alaska, co-author on GTR. Richard Shaw, CABI-UK, coordinated Japan trip, carried out preliminary host range testing of Aphalara itadori. Eric Coombs, Oregon Department of Agriculture. Provided ODA greenhouse space and plant care, suggested field sites. Alec McClay, McClay Ecosciences. Developed Canadian plant test list to combine with the U.S. test list. Robert Bourchier, Agrifood Canada. Provided input into test plant list, helped with surveys in Japan and test plant collection. Bernd Blossey, Cornell University. Coordinated East Coast interest in knotweed biocontrol program, provided test plants and technical advice Linda Wilson, University of Idaho. Brochure preparation and consortium coordination.
TARGET AUDIENCES: Target audiences include land owners, land managers, and agencies throughout temperate North America who are confronted with invasive knotweeds.
PROJECT MODIFICATIONS: The objectives of the research were extended as agreed upon by the sponsor to include importation of candidate biocontrol agents, collection and growing of test plant species, and host specificity testing of candidate biocontrol agents. This has required the rental of specialized quarantine facility space at Oregon State University.
Impacts
The research that we have carried out is crucial in allowing an evaluation of the possible risks and benefits of introducing the biocontrol agents. Assuming that a safe and effective biocontrol agent is found, biological control will provide a highly cost effective tool for long term management of an aggressive noxious weed. Our results indicate that all three insects studied have the potential to kill knotweed plants, at least in a laboratory setting. Potted plants defoliated by A. itadori and O. latipennis did not regrow from roots, even after several months. As for host specificity, we found that Aphalara itadori is capable of ovipositing on many of the non-target species, but at much lower rates than for the target plants. Adult feeding on non-target plants appeared to be much reduced based on presence of honeydew. So far, development of nymphs to adulthood was found on only two of the non-target plants and at much reduced rates in comparison to the target plant
species. Additional testing will be necessary to further evaluate any risk from these insects. Unfortunately, the moth O. latipennis was found to be too generalized in its feeding to be considered as a biocontrol agent and we terminated studies of this insect. Another species in the same genus, O. ovalipennis is reported to be host specific to knotweeds in Japan and future studies will focus on this species. Adult G. bifasciata were found to prefer knotweed plants to others, but did feed slightly on the ornamental Fallopia baldschuanica and on Rheum rhabarbarum (rhubarb). All of the work reported here is preliminary and further testing will be carried out during the next two years.
Publications
- McIver, J. and Grevstad, F. 2008. Natural Enemies of Invasive Knotweeds in the Pacific Northwest. Government Technical Report. Manuscript in preparation.
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Progress 10/01/05 to 10/01/06
Outputs
In 2005 and 2006, leaves from knotweed plants were collected from 31 locations throughout Washington and Oregon. The shape of the leaves and size of the hairs on the undersurface were used to identify species following Zika and Jacobson (2003). Twenty-four of knotweed patches examined were found to be hybrids, 5 were giant knotweed, and 2 were pure Japanese knotweed. For sites visited in 2006, the gender of the plant was also recorded. A majority of plants were found to have male flowers, with few or no seeds produced. In preparation for host specificity testing of candidate biocontrol agents, a list of plants to be tested was compiled using guidelines provided by the Technical Advisory Group on Biological Control of Weeds. The list includes more than 60 U.S. and Canadian plants of economic and ecological importance in the Polygonaceae and related families. More than half of the plants were obtained by us in 2006. These are being grown in a greenhouse at the Oregon
Department of Agriculture in Salem. The remainder will be collected in 2007. In May, the P.I. visited CABI-Biosciences at Silwood Park, United Kingdom to consult with Richard Shaw and others working on a biological control program for knotweed for Europe. Arrangements and preparations were made to use a quarantine facility at Oregon State University for future testing of candidate biocontrol agents. The P.I. attended and presented several meetings and conferences including a Knotweed Conference in Ithaca, NY, the Pacific Northwest Invasive Plants Conference in Seattle, the Clallam County knotweed meeting, and the Oregon Interagency Noxious Weed Conference, and others.
Impacts
Japanese and giant knotweeds are aggressive invaders of riparian zones throughout the Pacific Northwest and the Northeastern U.S. Introduced from Japan, these plants crowd out native plants, alter stream ecosystems, cause erosion, and potentially affect salmon and other wildlife. Our research to develop a biological control program will provide a cost effective and ecological means of controlling these plants on nationwide scale.
Publications
- No publications reported this period
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Progress 10/01/04 to 10/01/05
Outputs
In preparation for a biological control program against Japanese and Giant knotweed (Fallopia japonica and F. sachalinense), surveys were conducted in 2004 and 2005 throughout Washington and Oregon to determine which natural enemy species are already using these plants as hosts in the Pacific Northwest. During 2005, follow-up investigations were carried out on some of the natural enemies that were found in the previous summer. A pathologist from California Department of Agriculture was consulted regarding the possibility that leafhopper, Graphocephala atropunctata, found on knotweed along the Oregon Coast might be vectoring Pierces disease on knotweed. Another species that I had intended to study further was Galerucella nymphaeae, a native generalist chrysomelid beetle, which was found feeding on Giant knotweed at only one location near Willapa Bay, WA in August 2004. I visited this site on two occasions in 2005, but did not find the beetles. I conclude that the use
of Giant knotweed by this beetle species is an erratic event and not likely to contribute to control. Five species of insects that I was unable to identify were sent to USDA-ARS for identification. These include 2 aphids, a mirid, a psyllid, and a cicadellid. The psyllid has been identified as Aphalara spp. and identities of the others are still being determined. Leaves were collected from 10 locations throughout the lower Columbia River region in July. The shape of the hairs on the leaves was used to identify species following Zika and Jacobson (2003). A majority of plants in the Columbia Pacific region appear to be the hybrid, but pure Japanese and pure Giant can also be found. I am recording GPS locations for all plants identified in this way. It was found that the leaf hairs could be discerned in the field using a field lense and so further identifications (next spring and summer) will be made in the field. Several potential biological control release areas have been identified.
In Washington, these include the Naselle River area in Southwest Washington, the Cedar River in King County, areas surrounding Forks on the Olympic Peninsula, and Mill Creek in Southeastern Washington. In Oregon, potential release areas included Big Creek along the central Oregon Coast, Hells Canyon region, and the Luckiamute River near Corvallis. An additional potential release area was suggested by the Oregon Dept. of Agriculture along the Lower Nehalem River near Tillamook. The site is privately owned with approximately 10 acres of knotweed. Dick Reardon (U.S. Forest Service) visited the lower Columbia region in July. He was taken on a tour of the Nasselle, WA area where knotweed is especially abundant and visited some of the potential release areas in this region. A list of plants to be used in host specificity testing of candidate biocontrol agents was compiled using guidelines provided by the Technical Advisory Group on Biological Control of Weeds. Many of the plants on the list
are already being tested for a biological control program against knotweed species in Europe.
Impacts
The USDA Forest Service is developing a classical biological control program against Japanese and Giant knotweeds using natural enemies introduced from Asia. Our surveys have demonstrated the need for such a program due to a lack of existing natural enemies providing control over these plants. Moreover, development of a plant test list and the careful selection of release sites are both necessary steps that will allow the program to proceed.
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
In preparation for a biological control program against Japanese and Giant knotweed (Fallopia japonica and F. sachalinense), surveys were conducted throughout Washington and Oregon to determine which natural enemy species are already using these plants as hosts in the Pacific Northwest. A total of 68 sites invaded by knotweed were surveyed. For each site surveyed, we characterized the habitat as upland, streamside, or upper stream bank, and the light level as shady, partial sun, or full sun. We also recorded the 3 or 4 dominant plant species in surrounding plant community. At each patch, 10 stems were randomly selected from different sections of the knotweed patch. The leaves, exterior stems, and flowers (if present) were carefully searched for herbivorous invertebrates or diseases. It was also noted whether the herbivores were clearly feeding and/or reproducing on the plant vs. merely resting. The stems were then dissected to see if anything was feeding inside.
Between 5 and 10 root/rhizome sections were then dug and/or pulled up and dissected. After obtaining this quantitative data, the entire patch was scanned for any additional herbivory or disease, which was noted separately from the quantitative data. Sites west of the Cascade Range were visited once during either the period May 26 through June 3, or June 21 through July 2. The eastern Oregon and eastern Washington sites were visited between August 17 and August 20. A subset of the sites in the vicinity of Astoria, OR, were surveyed a second time between September 7 and September 10. A total of at least 50 different species of herbivorous insects and other invertebrates were found feeding on invasive knotweed species in the Pacific Northwest. A majority of these were probably transients that were not actually using the plant as a host. However, at least 17 species were clearly feeding or using the plant as a host. All of these species were feeding on the leaves or outer stem of the
plant. No stem-borers or root-feeders were found. The most common herbivore found was Philaenus spumarius, the meadow spittlebug. It was sampled at a total of 27 sites. Another widespread species was Isia isabella, the woolly bear caterpillar. Many aphid species were found on knotweeds but none were abundant enough to be damaging nor were they widespread. Only 3 aphid species were clearly reproducing on the plant. One of the most damaging insects found was a leafhopper identified as Graphocephala atropunctata, commonly known as the blue-green sharpshooter. This species was only found at one location. In general, the level of damage to knotweed plants from herbivory or disease was found to be very low. Several areas that are heavily invaded by knotweed were identified as possible release sites for future biological control agents that will be imported from Asia. In Washington, these include the Naselle River area in Southwest Washington, the Cedar River in King County, areas
surrounding Forks on the Olympic Peninsula, and Mill Creek in Southeastern Washington. In Oregon, potential release areas included Big Creek along the central Oregon Coast, Hells Canyon region, and the Luckiamute River near Corvallis
Impacts
The USDA Forest Service is developing a classical biological control program against Japanese knotweed using natural enemies introduced from Asia. Prior to introducing new natural enemies, it is essential to document the existing community of natural enemies that use the target weed as a host. Our work will provide documentation that none of the Asian natural enemies currently being studied for their suitability as biocontrol agents are already present in the Pacific Northwest. Our work also demonstrates the need for introducing specialized natural enemies, because none of the existing natural enemies are causing enough damage to provide control over knotweeds. Knowledge of the existing herbivore community will also allow biocontrol practitioners to consider, in advance, possible interactions between existing and introduced natural enemies. The selection of potential release sites will ensure that the biocontrol program can be implemented effectively and expediently
as soon as the agents are approved for importation. Finally, at least one species that we found may have potential for redistributing as a native biocontrol agent. However further research is needed.
Publications
- No publications reported this period
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