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Knotweed Biocontrol: The Saga Begins
Joel Price Biological Control Entomologist Oregon Department of Agriculture
Credit: Jon Wagner
Knotweed - Fallopia spp. • Polygonaceae (distinct and well-defined group)
• Buckwheat/smartweed family • 12 spp. Worldwide - Two native relatives
• Fringed bindweed (New England) • Climbing buckwheat (East of Rockies)
Credit: rshantz.com
Credit: Glen Mittelhauser Credit: Missouri Department of Conservation
Range Native to Japan, China, Korea, and Taiwan
Credit: thejapaneseknotweedcompany.com
Credit: discoverlife.org Credit: jksl.com
Invaded Range • Present in 42 states, Listed in 23 states • NY 1873
Credit: eddmaps.org
Credit: planttracker
Japanese, Giant, Bohemian
Knotweed Biology • Herbaceous perennial
• Re-sprout yearly • Mainly spread through
rhizomes • Flooding events
fragment • Panicle-like flowers in
Sept. • Seeds in Oct. • Either male, female,
or both • High germination in
lab, low in field
Credit: Calumet Co., WI
Giant knotweed Fallopia sachalinensis
Japanese knotweed Fallopia japonica
Japanese Giant
Giant Japanese
Japanese Giant Height (m) 2 4 Stem branching Profuse Sparing Leaf size (cm) 5-15 15-30 Vein hair Short Long Infloresence Terminal & Axillary Axillary
Credit: Elizabeth Farnsworth
J G
Bohemian knotweed Fallopia x bohemica • Hybrid species
• 70% plants surveyed • Morphological continuum making ID difficult • Himalayan knotweed (Perisicaria wallichii) in same family but not
closely related and not attacked Credit: Naturedigger
Impacts • Shades out competition • Allelopathic • No known wildlife benefit • Prevents tree establishment
• needed fish habitat shade • Holds onto nitrogen
• Senescing leaves nutrient poor
• Lacks generalist insect herbivores • Patches lack
entomophagous birds, frogs, ect.
• Minimal surface roots and senescing stems allow soil erosion
• Washington: cost of knotweed control 2004-2016: $30.4 million
• Could lose an additional $4.5 million in annual business sales, 25 jobs, and $1.2 million in income if knotweed infestations are allowed to increase by just 1% per year (Community Attributes Inc. 2017)
Aphalara itadori Order: Hemiptera • Adults resemble mini-cicadas • Suck sap from phloem cells • Exude honeydew utilized and
protected by ants
Credit: songsofinsects.com
Credit: Mike Lewis, UC Riverside
Aphalara itadori Credit: CABI
• 600 eggs per female • 33 day lifecycle Adults • overwinter in conifer bark • winged with flight season Lerp • crystallized honeydew • produced by larvae as
protective cover
Biotype Strains 1% DNA variation Northern Hokkaido Strain • Hokkaido island • Better impact on giant and
hybrid Southern Kyushu Strain • Kyushu island • Released in the UK 2010 • Better impact on Japanese Crossed Strains • Attacks all three knotweeds
Geographical Range • Sparse in native range
• Likely due to predation • From 31o - 50o N (CAN to MX) • Up to 7,000 ft elevation
• Permanent snowline • Climate matching project
• Willamette valley • Hokkaido psyllid better in
north – Giant/hybrid
• Kyushu psyllid better in south – Japanese
• Oregon State University (Corvallis, OR) • Since 2010
• CABI (Surrey, UK) • AAC Lethbridge Research Centre (Alberta)
Potential Agent Testing
Testing • 70 plants tested overall • All T & E Polygonacceae • All within genus • All ornamental varieties Test types: • No-choice development • Multiple choice • Oviposition choice • Field choice in U.K. • Multiple generation • Impact
No Choice
Choice Test
Credit: CABI
Field Cage Test
Credit: CABI
Credit: CABI
Dock - sorrel
Bell - jalapenos
Strawberry
Safety Testing Results • 92-98% host selection
fidelity, no-choice • Low egg/nymph survival • Up to several weeks more
required for development (42 d vs. 70 d)
• No long term survival – die out in F2 generation
• Nontarget will be closely watched
• Lives near buckwheat crops (soba noodles) in Japan with no spillover
– Since 8th century
Credit: Cornell
Impacts • After 50 days in lab:
– above and below ground biomass 50% of control
• 67% F. sachalinensis dead • 13% F. bohemica dead
F. Grevstad et al. 2013
UK and CAN have only 10% Giant/Bohemian
Credit: Irish Examiner Ltd.
Leaf curling reduces photosynthesis and shields psyllids from predation
Credit: Fritzi Grevstad (OSU)
Permitting Process
6. PETITION TO TAG
Petition sent to TAG by APHIS
6
APHIS sends reviewers form with
due date
5 mo. X7 2 mo. 8 1 mo. 9 24 mo. 4 mo.
7. TAG REVIEW AND RECOMMENDATION
Reviewer comments compiled by Chair
Chair authors recommendation letter; sends to
APHIS
8. PERMITTING DECISION
Permitting officials review letter, data
and comments
Decision letter is sent to petitioner
and APHIS PPD
9. ENDANGERED SPECIES ACT REVIEW
FWS reviews data, investigates concerns
FWS signs concurrence or non-concurrence letter
10. NATL. ENV. POLICY ACT / TRIBAL
CONSULTATION
APHIS drafts, publishes Env.
Assessment. Tribal Consultation.
APHIS prepares, finalizes regulatory
workplan
11. PUBLIC COMMENT
Public comment period on Env.
Assessment 30 days
APHIS completing consultation process.
12. ENV. FINDING
APHIS responds to comments on env.
findings
Env. Impact finding signed by APHIS PPQ Official; publish EA
and findng
13. PERMIT COMPLETION
APHIS completes permit process
(issuance or denial)
Permit or other correspondence
signed and issued
10 12 mo. 11 1 mo. 13 1 mo.
2 to 4 years
[7 mo.] [8 mo.] [32 mo.] [44 mo.] [45 mo.] [49 mo.] [50 mo.]
Actio
n
Des
crip
tion
12
Over 100 years worldwide BC use: 99% of weed biocontrol have no known significant adverse effects on non-target plants (Suckling &
Sforza 2014, Schwarzlaender et al. 2018).
303 Comments
“This is horrible, to release a bug into an area to destroy a beneficial flower…that makes thee best honey ever... Releasing insects to an area that they are not native to is always a horror...”
“History is rife with experiments like these run amok.”
“Eradication of this plant would be a huge mistake.”
“this agency is sneaky and hides from public knoiwledge...i do not trust aphis for one minute. we are better off with the knotweed...aphis needs to be closed down. it is a vile, wicked, evil agency thatsneaks around america killign wildlife, birds...they sneak into a town telling nobody they are there tokill animals. they put down cyanide and m44s to kill animals which thenkill people and dogs and eagles...a negaitve agency for all of america. no such invasion of this insect shuold be permitted in america.”
Bee Holdups • Empire State Honeybee
Producers – Knotweed utilized to some
extent for fall food source
• 30 day federal register comment period ext. 60 days to Aug. 28th
• OSU response – Prerelease studied since 2004 – Works over decades – Leaves a portion of infestation – Allows for influx of greater pollen
diversity – Preferable to other lawful control
• NY Beekeeper, “commend even-handed comments…clear and reasoned.”
• Signed FONSI for Brazilian Peppertree (Schinus terebinthifolia) in June
• We expect signed permit
Release • Emergence time of April 15th • Population ramp up in greenhouses • Limited local caged releases year 1 • Widespread diverse approach year 2 • Monitor spring generation and later
mid-summer generation • Permanent quadrats measuring
height, diameter, density • Sticky cards to measure spread • Psyllids provide base of food chain
for insectivores currently absent in heavily infested areas
Credit: svgsilh.com
