5)Management c)Control iii)Biological methods = “biologically” damaging plants

5)Management c)Control iii)Biological methods = “biologically” damaging plants Biotic constraints/enemy release hypothesis

5)Management c)Control iii)Biological methods = “biologically” damaging plants Biotic constraints/enemy release hypothesis If plants are invasive because they have escaped natural enemies, introducing the natural enemies should help control the invasive!

5)Management c)Control iii)Biological methods Least public opposition

5)Management c)Control iii)Biological methods Least public opposition Recall Federal Plant Protection Act : Biological control is often desirable

5)Management c)Control iii)Biological methods Least public opposition Recall Nevada noxious weed legislation: Weed control analyst researches biological control options

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia W. Plants Database

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Chronology (source: ) W. Plants Database

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Chronology (source: ) Introduced in 1788 with the First Fleet – dye industry Additional introductions for forage and hedges though 1800s Numerous species Problem acknowledged 1870 W. Plants Database

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Chronology (source: ) Introduced in 1788 with the First Fleet – dye industry Additional introductions for forage and hedges though 1800s Numerous species Problem acknowledged : prickly pear destruction act 1910: ‘Roberts Improved Pear Poison’ created – 80% sulfuric acid, 20% arsenic – considered best weapon

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Chronology (source: ) Early chemical control: fumes from boiling arsenic Photo: © L. R. Tanner

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Chronology (source: ) Early chemical control: boiling arsenic 1912 problem rampant: begin looking for biological control

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Chronology (source: ) Early chemical control: boiling arsenic 1912 problem rampant: begin looking for biological control Photo: © L. R. Tanner

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Chronology (source: ) Early chemical control: boiling arsenic 1912 problem rampant: begin looking for biological control 1925, infested twenty-five million hectares in New South Wales and Queensland. It was spreading at the rate of half a million hectares a year.

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Chronology (source: ) introduction of Cactoblastis moth Photo: © L. R. Tanner

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Chronology (source: ) introduction of Cactoblastis moth By 1932, most of the prickly pear stands had been decimated. Photo: © L. R. Tanner

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Chronology (source: ) introduction of Cactoblastis moth By 1932, most of the prickly pear stands had been decimated Photo: © L. R. Tanner

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Summary: spectacularly successful BUT Took 14 years to find biocontrol agent ( ) Some cool-climate stands remained; insect less effective

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Prickly pear (Opuntia spp.) in Australia Summary: spectacularly successful BUT Took 14 years to find biocontrol agent ( ) Some cool-climate stands remained; insect less effective Opuntia aurantica becomes more problematic

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Klamath weed (Hypericum perforatum) in California

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Klamath weed (Hypericum perforatum) in California Broad-leaved, perennial herb Introduced from Europe in 1793; reached California late 1800’s Extremely invasive; toxic By early 1940’s: 5 million acres of infested rangeland Biological control in California: $750,000 total cost By early 1960’s insects had reduced acreage to <1% of peak

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Tamarix in western US: Photos: Bob Conrad, NAES

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Tamarix in western US: SourceL Swedhin et al (Tamarisk Research Conference, Fort Collins CO) Large scale dispersal and population expansion of Diorhabda elongata in CO, NV, and UT after initial releases Near Moab: two release sites in In 2005, less than 2 acres of tamarisk defoliated. In 2006, 109 acres defoliated, 4.1 miles upstream from release sites and area was expanding Expansion of beetles from UT release sites on Colorado River into CO expected by summer 2007

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations:

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Finding an enemy

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Finding an enemy ID promising species in native range Test for host specificity USDA has facilities in other countries for this purpose

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Finding an enemy ID promising species in native range Test for host specificity USDA has facilities in other countries for this purpose e.g. Montpelier, France Photo © USDA ARS-EBCL Current projects: Canada Thistle, Field Bindweed Giant reed, Knapweeds, Leafy Spurge, Lepidium draba, Rush Skeletonweed, Saltcedar, Swallow- worts, Yellow Starthistle

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Finding an enemy ID promising species in native range Test for host specificity USDA has facilities in other countries for this purpose e.g. Montpelier, France Also Rome, Italy and Thessaloniki, Greece Photos © USDA ARS-EBCL

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Finding an enemy Host specificity: specialists not generalists

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Finding an enemy Host specificity Mode of action (plant part affected)

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Finding an enemy Host specificity Mode of action (plant part affected) Type of organism (disease, insect)

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Finding an enemy Host specificity Mode of action (plant part affected) Type of organism (disease, insect) Climate requirements of organism (climate matching for source populations and introduction sites) e.g. some releases of Diorhabda from Texas populations not successful at higher latitudes – couldn’t overwinter

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Finding an enemy Host specificity Mode of action (plant part affected) Type of organism (disease, insect) Climate requirements of organism (climate matching for source populations and introduction sites) Estimated that about ½ of introduced weed bio-control insect species establish in new location

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Finding an enemy Non-target effects

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Finding an enemy Non-target effects Specificity of biocontrol agent Relatedness of flora

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Non-target effects – Pemberton (2000)

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations: Non-target effects

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations Non-target effects

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations Non-target effects

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations Non-target effects

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations Non-target effects

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations Non-target effects

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations Non-target effects

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations Non-target effects

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Difficulty locating enemy Non-target effects – From Pemberton (2000)

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Difficulty locating enemy Non-target effects – From Pemberton (2000)

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations Non-target effects

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Considerations Non-target effects

5)Management c)Control iii)Biological methods Least public opposition Number of success stories Difficulty locating enemy Non-target effects Most likely a problem when the invasive species has closely related plants in the invaded area