Integrated Weed Control Project - Biological Control

Integrated Weed Control Project- Biological Control-

Jennifer AndreasIntegrated Weed Control Project Director

[email protected](206) 205-3135

What is Biocontrol?The intentional use of one living organism to control/suppress another organism, such as WEEDS

Caesar, USDA ARS; bugwood.org

Nematodes

Piper, WSU; bugwood.org

Pathogens

Healing Hooves

Mammals

WSU Extension

Insects

Integrated Weed Management

• Decision-making process

• Strategy for effective weed suppression

• Ecologically-based

• Combination of weed control methods– physical, cultural, chemical, biological

Advantages• Safe – USDA APHIS approves biological

control agents before introduction into U.S.

• Ecologically desirable – herbicide alternative

• Insects are mobile

• Long-term solution

• Cost effectiveWSU Extension

• Long time to make impact

• Subject to predators

• May not establish at some sites

• Very slow approval of new agents

• No eradication

Limitations

Predatory mite

Predatory insect

dinosaurtheory.com

• Established weed infestations

• Remote, inaccessible, less disturbed areas

• Areas not controlled by other means

• Environmentally sensitive sites

When to use biocontrol?

Dargatz, Jefferson CNWCB. WA

WSU Extension

• Small or new infestations

• Highly disturbed areas

• Roads or traveled paths

• Areas unfavorable for insect

• On weeds with no approved agents

When NOT to use biocontrol?

Schwarzlaender

Mazerolle, Air

Mazerolle, Air

Knapweeds

WSU Extension

Spotted knapweed(Centaurea stoebe spp.micranthos)

Diffuse knapweed(Centaurea diffusa)

Meadow knapweed(Centaurea pratensis)

WSU ExtensionWSU Extension

- spread by seed- ↑ soil erosion- ↓biodiversity- ↓quality forage

WSU Extension

Knapweed Biocontrol Agents

WSU Extension

Adult

Larinus obtusus- seed-head feeding weevil- attacks spotted, meadow &

diffuse - currently best agent for meadow- ↓ seed production

WSU Extension

Larva consumes seeds

Adults devouring diffuse knapweed

Larinus minutus- seed-head feeding weevil- attacks diffuse, spotted & meadow - strong impact on diffuse in eastern WA- adults can defoliate plants- ↓ seed production

Success with Larinus minutus !• diffuse knapweed reduced dramatically

Before biocontrol agent release

After biocontrol agent release

WSU Extension WSU Extension

Knapweed Biocontrol Agents

- root-feeding weevil- attacks spotted & diffuse- ↓ biomass & density- can kill plants - good success in

Montana with L. minutus& root weevil

Cyphocleonus achates

WSU Extension

WSU Extension

Larva Larval root damage

Adult

Additional Knapweed Agents

Chaetorelliaacrolophi& Terellia virens- seed-feeding flies- attacks spotted & diffuse

- prefers cool, wet sites

Bangasternus fausti

- seed-feeding weevil- attacks diffuse & spotted

- prefers hot, dry environments

Sphenopterajugoslavica

- root-feeding beetle- attacks diffuse, maybe spotted

- prefers hot, dry environments

Agapeta zoegana- root-feeding moth- attacks spotted & diffuse- impact unknown

Seed-feeders Root-feeders

Rees, USDA ARS; bugwood

Nez Perce Biocontrol Center, ID; bugwood.org

USDA APHIS PPQ; bugwood

USDA APHIS PPQ; bugwood.org

USDA APHIS PPQ; bugwood.org

Adult lays eggs in seed-head

Purple loosestrife

- herbaceous perennial- aquatic, wetland sites- displace native vegetation- degrades wildlife habitat &

hunting/ fishing areas- ↓ water flow

Lythrum salicaria

Agriculture and Agri-Food Canada;.bugwood.org

WSU Extension

Purple Loosestrife Biocontrol

WSU Extension

Beetles skeletonized loosestrife in Pierce County

WSU Extension

Mating adults

Eggs Larva

Galerucella calmariensis / G. pusilla- foliage-feeding beetles- highly effective - larvae & adults devour foliage- do not like tidal-influenced waters

Purple Loosestrife Biocontrol


Coombs, ODA; bugwood.org

Larva mining flower-head

AdultCoombs, ODA; bugwood.org

Schwarzlaender, UI

Larva mines root

Adult

Hylobius transversovittatus- root-feeding weevil- best combined with leaf beetles- kills small roots in 2 years with

several larvae- difficult to collect

Nanophyes marmoratus- bud/ flower-feeding weevil- outcompeted by leaf beetles- ↓ seed production

Scotch Broom

WSU Extension

Coombs, ODA

Adult lays eggs into developing seedpod

Larva consume developing seed


Adult

Cytisus scoparius- perennial shrub- displace forage & native

species- impacts timber, rangeland

Exapion fuscirostre- seed-feeding weevil- widespread- ↓ seed production

Bruchidius villosus- seed-feeding bruchid- ↓ seed production up to

90%

Tansy Ragwort

Senecio jacobaea- biennial, unless

mowed/cut- toxic to cattle & horses

Lee, San Juan County Noxious Weed Board

Lee, San Juan CNWCB

WSU Extension

Tansy Ragwort Biocontrol

WSU Extension

USDA ARS EBCL; bugwood.org

WSU Extension

WSU Extension

Coombs, ODA Adult feeding holes

Larva mining in leaf

Adult

Longitarsus jacobaeae- root-feeding flea beetle- excellent agent- widespread- Italian & Swiss strains


Adult

Tansy Ragwort Biocontrol

WSU Extension

Larva consuming seeds

Tyria jacobaeae (cinnabar moth)- foliage-feeding moth- effective in large numbers but

plants are often able to flower- non-target concerns

Botanophila seneciella- seed-feeding fly- widespread


Adult

WSU Extension

Larvae consuming foliage

R. Lee, San Juan

St. JohnswortHypericum perforatum

WSU Extension

Rees, USDA ARS; bugwood.org

• 1 million hectares in northern California infested in 1944

- perennial, rhizomatous- causes sensitivity to sun- poster child for biocontrol success- now considered mainly a roadside or wasteland weed

St. Johnswort Biocontrol

Chrysolina spp.- foliage-feeding beetle- poster child for biocontrol success!


Harris, AAFC

Rees, USDA ARS; bugwood.com

Eggs

Larvae

Adult

USDA EBCL; bugwood.org

Monument to beetle (and researchers) in California, celebrating success

St. Johnswort Biocontrol


larvae

Adult moth


Adult beetle

Larva mining root

Aplocera plagiata- foliage-feeding moth- success unknown- difficult to collect in large

numbers

Agrilus hyperici- root-boring beetle- success unknown- difficult to collect in large

numbers

Rush Skeletonweed

Chondrilla juncea- long-lived herbaceous perennial- spread by seed & vegetative regrowth- over 404,000 ha in Washington- competes with crop plants- latex hinders crop production- displaces desirable forage


Dewey, Utah State U.; bugwood.org

Rush Skeletonweed BiocontrolEriophyes chondrillae- gall-forming mite- most effective agent- ↓ plant vigor / stunts plants- ↓ seed production- kills seedlings

Puccinia chondrillina- rust fungus- effective- ↓ seed production- ↓ plant vigor- can kill seedlings



Turner, USDA ARS; bugwood.org

Rush Skeletonweed BiocontrolBradyrrhoa gilveolella- root-mining moth- can kill above-ground tissue- establishment questionable- may be available for trials

Cystiphora schmidti- gall midge (fly)- effective- can kill rosettes and stems- ↓ plant vigor- ↓ seed weight & viability


USFS

Canada Thistle

Urophora cardui- stem-galling fly- ↓ plant vigor- works in conjunction with plant

competition

Cirsium arvense- creeping perennial- ↓ forage- competes with crops

The Nature Conservancy

University of Wisconsin

Oregon State University

WSU Extension

Adult

Larva inside plant create gall

WSU Extension


Bull Thistle

Cirsiumvulgare

Shepard, USFS; bugwood.org

Colquhoun; Oregon State U

Urophora stylata- seed-feeding fly- ↓ seed production

WSU Extension

- biennial- prevalent in heavily disturbed sites

Harris, AAFC; bugwood.org

Larvae consume developing seeds

Adult

WSU Extension

Additional Biocontrol

• Biocontrol agents may be available in your area for:– gorse– bindweed– puncturevine– saltcedar– Mediterranean sage

• Class A – must be controlled in Washington

WSU Extension’s Role• State-wide program

• Provide biocontrol agents free of charge to land managers

• Education to land managers

• Expertise and on-site recommendations

Connett, UI; bugwood.org

Integrated Weed Control Project - Biological Control

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