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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 1 Introduction – What is Biological Control? • Using organisms to control pests • Can include pathogens, vertebrates, invertebrates to control weeds, insects, etc. – – – 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 4 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 – – – – No-choice testing Whole plant tests Oviposition tests Field testing (N Am plants imported to a foreign country) 5 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! 6 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 7 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) 8 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 9 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) • • 10 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 11