Weed Biological Control Weed Biological Control Principles and Procedures Principles and Procedures

J. P. CUDAJ. P. CUDA

ENTOMOLOGY & NEMATOLOGY DEPARTMENTENTOMOLOGY & NEMATOLOGY DEPARTMENTGAINESVILLE, FL 32611-0620GAINESVILLE, FL 32611-0620

Instructor: Instructor: Dr. Jim CudaDr. Jim Cuda phone (352-392-1901 ext 126) phone (352-392-1901 ext 126) email (jcuda@mail.ifas.ufl.edu) email (jcuda@mail.ifas.ufl.edu)

Research Area: Research Area: Biological Control Biological Control of Aquatic & Terrestrial Weedsof Aquatic & Terrestrial Weeds

TopicsTopics• Weed Biological Control ConceptsWeed Biological Control Concepts• Steps in a Classical Biological Steps in a Classical Biological

Control ProgramControl Program

What is a Weed ?What is a Weed ?• A plant out of place A plant out of place (HOLM ET AL. 1977)(HOLM ET AL. 1977)

• Introduced or native plant growing Introduced or native plant growing in a situation where it has a in a situation where it has a detrimental effect on conservation detrimental effect on conservation areas, humans, or their areas, humans, or their environment environment (HARLEY & FORNO 1992)(HARLEY & FORNO 1992)

Strategies Used ForStrategies Used ForWeed ManagementWeed Management

Control MethodControl Method

• MechanicalMechanical

• ChemicalChemical

• BiologicalBiological

InfestationInfestation

• SmallSmall

• ModerateModerate

• WidespreadWidespread

Criteria for Selecting a Weed as Criteria for Selecting a Weed as a Target for Biological Control a Target for Biological Control

• Cause sufficient damageCause sufficient damage– Agricultural Agricultural – EcologicalEcological

• No critical beneficial valuesNo critical beneficial values• Existence of natural enemiesExistence of natural enemies

What is Biological What is Biological Control ?Control ?

• Use of live natural enemies to suppress Use of live natural enemies to suppress weed densities or populationsweed densities or populations

• Examples of natural enemies :Examples of natural enemies :– PathogensPathogens (nematodes & diseases)(nematodes & diseases)

– ArthropodsArthropods (insects & mites)(insects & mites)

– FishFish (grass carp)(grass carp)

Biological Control vs. Biological Control vs. Natural RegulationNatural Regulation

• ““Biological Control”Biological Control” is an action is an action taken by peopletaken by people

• ““Natural Control or Regulation”Natural Control or Regulation” has no human involvementhas no human involvement

Biological Control MethodsBiological Control Methods1.1. Non-Classical Biological ControlNon-Classical Biological Control

a.a. Augmentative ApproachAugmentative Approach

b.b. Inundative ApproachInundative Approach

2.2. Classical Biological ControlClassical Biological Control

1. Non-Classical Biocontrol1. Non-Classical Biocontrola.a. Augmentative Augmentative

- Mass rearing and release of a- Mass rearing and release of a biological control agent to increase biological control agent to increase its numbers and effect on the weedits numbers and effect on the weed- Applies to fish (grass carp) and some - Applies to fish (grass carp) and some

insects (milfoil weevilinsects (milfoil weevil))

1.1. Non-Classical BiocontrolNon-Classical Biocontrol

b.b. Inundative:Inundative: - - Formulation and application ofFormulation and application of pathogens to control weedspathogens to control weeds

- Applies to mycoherbicides- Applies to mycoherbicidesCercospora rodmaniCercospora rodmani – Water Hyacinth – Water Hyacinth

Mycoleptodiscus terrestrisMycoleptodiscus terrestris - Hydrilla- Hydrilla

2. 2. Classical Biological ControlClassical Biological Control• Introduction of natural Introduction of natural

enemies from their native enemies from their native range to control an range to control an invasive exotic weedinvasive exotic weed

• Most widely used methodMost widely used method

Ecological Basis for Classical BCEcological Basis for Classical BC

• Some natural enemies are host specificSome natural enemies are host specific (WAPSHERE ET AL. 1984)(WAPSHERE ET AL. 1984)

• In the absence of their own predators In the absence of their own predators and diseases, densities of natural and diseases, densities of natural enemies are influenced by their host enemies are influenced by their host plant abundanceplant abundance (DEBACH 1974, HUFFAKER 1984)(DEBACH 1974, HUFFAKER 1984)

BIOLOGICAL CONTROLBIOLOGICAL CONTROL(= APPLIED ECOLOGY)(= APPLIED ECOLOGY)

2o

1o Consumer

Producer (WEED)

WEED1o Consumer(BIOAGENT)

WEED

Objective of Biological Weed ControlObjective of Biological Weed Control

• Introduce or apply natural enemies Introduce or apply natural enemies that can suppress and maintain the that can suppress and maintain the density of the weed at density of the weed at “ACCEPTABLE” levels“ACCEPTABLE” levels

• Biological Control is Biological Control is NOTNOT eradication eradication

Conceptual Basis for Conceptual Basis for Weed Biological ControlWeed Biological Control

• Weed establishes Weed establishes equilibrium density equilibrium density (ED)* above (ED)* above economic injury economic injury level (EIL)**level (EIL)**

• Natural enemy Natural enemy lowers ED & lowers ED & maintains it below maintains it below EILEIL

*ED - Long term mean density*ED - Long term mean density**EIL – Lowest density causing **EIL – Lowest density causing

economic or ecological economic or ecological damagedamage

TIME

NU

MB

ER EIL

ED

EDNatural Enemy

Weed

Defining Biocontrol SucessDefining Biocontrol Sucess

• Complete-Complete- No other control methods No other control methods are needed are needed

• SubstantialSubstantial- Other methods needed - Other methods needed but at reduced level but at reduced level

• Negligible-Negligible- Other methods are Other methods are required required (HOFFMANN 1998)(HOFFMANN 1998)

Advantages of Biological Advantages of Biological ControlControl

• Minimal impact on non-targetsMinimal impact on non-targets• Environmentally friendlyEnvironmentally friendly• Classical biocontrol is permanentClassical biocontrol is permanent• Suitable for weeds of natural areasSuitable for weeds of natural areas• Relatively inexpensiveRelatively inexpensive

Costs / Benefits of Classical Costs / Benefits of Classical Weed Biocontrol ProgramsWeed Biocontrol Programs

(after Mentz 1987)

Release of Bioagent

Time

Benefits (+$)

Costs (-$)

Research & Development

Maintenance & Monitoring

Disadvantages of Biological ControlDisadvantages of Biological Control• Control is not immediate (5–10 years)Control is not immediate (5–10 years)• Except for mycoherbicides, little Except for mycoherbicides, little

interest in commercializationinterest in commercialization• UnpredictableUnpredictable

– Some natural enemies fail to establishSome natural enemies fail to establish– Some natural enemies are ineffectiveSome natural enemies are ineffective

Summary of Steps in a Classical Summary of Steps in a Classical Biological Control ProgramBiological Control Program

USDA-ARS

Procedure for Classical Procedure for Classical Weed Biological controlWeed Biological control

1.1. Project InitiationProject Initiation2.2. Seek Approval and Funding Seek Approval and Funding 3.3. Foreign ExplorationForeign Exploration4.4. Domestic Surveys Domestic Surveys 5.5. Ecological Studies on Weeds & AgentsEcological Studies on Weeds & Agents

Procedure for Classical Procedure for Classical Weed Biocontrol Weed Biocontrol (CONT’D)(CONT’D)

6. 6. Host Specificity StudiesHost Specificity Studies 7. Seek Approval for Release of 7. Seek Approval for Release of

Agents Agents 8. Rearing and Release8. Rearing and Release 9. Evaluation of Effects9. Evaluation of Effects10. Distribution (& Augmentation)10. Distribution (& Augmentation)

Project InitiationProject Initiation• Determine Plant is Suitable TargetDetermine Plant is Suitable Target

– Conduct Literature Review on Weed Conduct Literature Review on Weed and its Natural Enemiesand its Natural Enemies• Taxonomy, Biology, Ecology, Distribution Taxonomy, Biology, Ecology, Distribution

– Demonstrate Economic / Scientific Demonstrate Economic / Scientific Feasibility and Resolve ConflictsFeasibility and Resolve Conflicts

Seek Approval and FundingSeek Approval and Funding

• Seek Political Support from Seek Political Support from StakeholdersStakeholders– Cattlemen’s AssociationsCattlemen’s Associations– Water Management DistrictsWater Management Districts

• Obtain Financial Support from Public Obtain Financial Support from Public and Private Sectorsand Private Sectors

Foreign ExplorationForeign Exploration

• Identify Native Range of Target Identify Native Range of Target WeedWeed

• Search for Natural Enemies in Search for Natural Enemies in Native RangeNative Range

Domestic SurveysDomestic Surveys

• Conduct Faunal Surveys of Weed Conduct Faunal Surveys of Weed in Introduced Rangein Introduced Range

• Compile List of Arthropods and Compile List of Arthropods and Pathogens Attacking Weed In Pathogens Attacking Weed In Area of IntroductionArea of Introduction

Ecological Studies on Weed Ecological Studies on Weed and Agentsand Agents

• Study Ecology of Weed and Its Study Ecology of Weed and Its Relatives in Native RangeRelatives in Native Range

• Identify Natural Enemies and Identify Natural Enemies and Study Their Biologies and Host Study Their Biologies and Host RangesRanges

Host Specificity StudiesHost Specificity Studies• Conduct Host Range Tests of Conduct Host Range Tests of

Promising Natural Enemies in Promising Natural Enemies in Country of Origin Country of Origin

– Open Field Tests PreferableOpen Field Tests Preferable• Study Host Specificity of Potential Study Host Specificity of Potential

Control Agents in Quarantine in Control Agents in Quarantine in Country of Introduction Country of Introduction

Economic, Nativeand Endangered spp.

Economic, Nativeand Endangered spp.

TargetWeedTargetWeed

Other Plant Species; same subgenusOther Plant Species; same subgenus

Other Subgenera; same genusOther Subgenera; same genus

Other Genera; same tribeOther Genera; same tribe

Plant Families of Economic/Aesthetic ValuePlant Families of Economic/Aesthetic Value

Plants Attacked by Relatives of BioagentsPlants Attacked by Relatives of Bioagents

Redrawn from Rees et al. (1995)

Centrifugal Phylogenetic MethodCentrifugal Phylogenetic Method (Wapshere 1974)(Wapshere 1974)

Screening Procedures Screening Procedures (Wapshere 1989)(Wapshere 1989)

Larval Feeding Test

Adult Oviposition Test #1

Adult Oviposition Test #2

NOT INHOST RANGE

NOT INHOST RANGE

NOT INHOST RANGE

+ -

+ -

+ -

TEST 1

TEST 2

TEST 3

IN HOST RANGE

No-Choice: Close Confinement

No-Choice: Close Confinement

Multiple Choice: Loose Confinement

Screening Procedures (cont’d)Screening Procedures (cont’d)

• No Choice TestsNo Choice Tests– Potted plantsPotted plants

– Cut foliageCut foliage

Screening Procedures Screening Procedures (cont’d)(cont’d)

Stem Cage Stem Cage

Paired TestPaired Test

Multiple Choice TestsMultiple Choice Tests

Small CagesSmall Cages

Large CagesLarge Cages

Seek Approval for ReleaseSeek Approval for Release• Prepare and Submit Report to Prepare and Submit Report to

Appropriate Regulatory Authorities Appropriate Regulatory Authorities Requesting Release of BioagentRequesting Release of Bioagent

• Options:Options:– Release ApprovedRelease Approved– Additional Host Specificity StudiesAdditional Host Specificity Studies– Request for Release DeniedRequest for Release Denied

Rearing and ReleaseRearing and Release

• If Release of Bioagent is If Release of Bioagent is Approved by Regulatory Approved by Regulatory Agencies:Agencies:

– Import Bioagent and Eliminate Import Bioagent and Eliminate Parasitoids and PathogensParasitoids and Pathogens

– Mass Rear and Release BioagentMass Rear and Release Bioagent

Evaluation of EffectsEvaluation of Effects

• Confirm Establishment of BioagentConfirm Establishment of Bioagent• Conduct Manipulative / Replicated Conduct Manipulative / Replicated

Field Experiments to Measure Field Experiments to Measure Population Level Effect of Bioagent Population Level Effect of Bioagent on Target and Non-Target on Target and Non-Target SpeciesSpecies

Distribution of BioagentDistribution of Bioagent

• Redistribute Bioagent from Site of Redistribute Bioagent from Site of Establishment or Field InsectariesEstablishment or Field Insectaries

• Collaborate with Public Agencies and Collaborate with Public Agencies and Volunteer Groups to Spread Volunteer Groups to Spread Bioagent throughout infested areaBioagent throughout infested area

For Additional Information on For Additional Information on Biologically Based Weed Biologically Based Weed

Management, Go To:Management, Go To:

http://biocontrol.ifas.ufl.eduhttp://biocontrol.ifas.ufl.edu