Download Biological Control Strategies for Alaska

Biological Control:
What is the status for Alaska?
Matthew L. Carlson
Assistant Professor & Program Botanist - Alaska Natural Heritage Program
& Biological Sciences Department, UAA [email protected]
Outline:
• Background
• Debates and
Conservation issues
• Process and
guidelines for biological
control
• Status in AK
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Introduction – What is Biological Control?
• Using organisms to control pests
•
Can include pathogens, vertebrates,
invertebrates to control weeds, insects, etc.
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–
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Feeding on leaves/stems, roots, seeds
Can cause >90% reduction in seed output
Generally, moderate impacts…
Introduction – What is Biological Control?
• Ecological Basis & History
Number of Individuals
– Populations, communities, “balance of nature,”
and “natural control of numbers”
Economic threshold
Time
2
Biological control and food webs
Competitive advantage & alteration of food webs
– Community restructuring/alteration of ecosystem
function
3
The hope following biocontrol is altered
communities, but …
What is the
basic process?
1. Return to native
range
2. ID host specific
enemies
3. Testing extensively
4. Rearing and
releasing enemies
in areas of the
pest’s introduction
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Process: Host specificity and
Testing of Insects
1. ID of insect (relatives in native
range?)
2. Can the insect complete its
lifecycle on the host
3. Is it a generalist?
- survey surrounding plants
- literature search
4. Begin trials on specialist
insect candidates
Process: screening other
plants
•
•
Insect behavior: its
importance to host specificity
testing
Preliminary screening a large
number of plants
–
–
–
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No-choice testing
Whole plant tests
Oviposition tests
Field testing (N Am plants
imported to a foreign country)
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Process: Rearing and release
Contexts where biocontrol are most successful?
•
Works best on large infestations of a single weed
species
•
Broadly distributed and too expensive to use
mechanical or pesticide treatments
–
Sensitive plant and animal communities
•
Usually combined with other control techniques
•
Don’t expect complete elimination of the pest!
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Advantages:
• (from USDA & Hoddle 2002):
1. Long-term management
(& Moves with the hosts)
2. Self-perpetuating agents
3. Targeted attack
4. Nonrecurring costs
5. “Known” level of risk prior to release
Disadvantages:
• So what are the costs?
1. Time
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Disadvantages:
• So what are the costs?
2. Direct Ecological Interactions
e.g., Cactoblastis cactorum & native
threatened cactus species (Stilling 2002)
Rhinocyllus conicus & native thistles (Louda
1999)
Narrow host specificity?
Disadvantages:
• So what are the costs?
3. Indirect Ecological Interactions
e.g., Specialist tephritid flies and moths on
knapweeds (Callaway 1999, Pearson
2000)
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Disadvantages:
• So what are the costs?
3. Indirect Ecological Interactions
e.g., cascading effects? (Pearson 2000)
Disadvantages:
• So what are the costs?
4. Successful control of 20% of weedcontrol projects (Louda & Stiling 2004)
5. Evaluation procedures lacking?
1. Not designed to measure quantitative
impacts on populations
2. Or to predict alternative outcomes in
communities
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Administrative Process
•
•
•
APHIS has the permitting
responsibility
multi-year/many step
process for proposer
TAG established
– to help researchers and
evaluate biocontrol agents
– recommends APHIS on
suitability
Biological Control Stages in Alaska
•
Japanese knotweeds (Polygonum
cuspidatum, P. sachalinense,
Polygonum ×bohemicum)
•
Evaluation of agents in eastern
US
ID of 12 agents from Japan
Development of test plant list
(incorporating AK information)
•
•
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Biological Control Stages in Alaska
Invasive hawkweeds (Hieracium
species)
• Program initiated in 1994
– USDA-ARS, France, hawkweed
herbivores
– Wilson & McCaffrey surveying
weedy & native hawkweeds
•
5 potential agents
– Studies will continue to quantify the
impact of these natural enemies
– We’re looking at natural enemies of
hawkweeds in AK
Conclusions
– How bad are the economic and ecological
effects of the invasive plant?
– We need to be aware of the ecological costs and
uncertainty of biocontrol
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