1. OUTLINE: Invasive species L16 and L17 OVERVIEW Impacts Which species invade? Which communities are invaded? MANAGEMENT Priorities Eradication Biological control

2. Management options Number of non-natives = Number introduced X survival rate Options Prevent entry

3. How are non-native plants introduced? Accidentally In hay or seeds In ships ballast Intentionally Medicinal plants Ornamentals Prevent erosion 85% of weeds are introduced intentionally

4. Why can’t we reduce introductions? Economic conflicts International trade imposes pressure to import plants Weak Regulations If not 100% certain it will be a problem it is difficult to stop US - only restricts import of KNOWN invasive weeds

5. Management options Number of non-natives = Number introduced X survival rate Options Prevent entry Improve control and eradication Requires Stronger regulatory framework Early detection rapid response and $$$

6. Management priorities for control and eradication Based on risk (potential impact)

7. Eradication The removal of a species from an area to which it will not return When is it possible? Population small Habitat defined Money and side effects no consideration

8. Eradication of Norway rats from Langara Island, BC Kaiser et al 1997 Problem Rats implicated in seabird population declines 4 spp had disappeared Feasibility Island Specific poison available Finance Oil spill $$$

9. Eradication of Norway rats from Langara Island, BC Langara Island 3100 ha Traps set on 100mx100m grid Trapping started 10 Jul 1995 Last rat Sept 1995

10. Why was eradication successful? effective poison island territoriality of rats rat population already stressed Ancient murrelets - have not recovered ---> Heather Major (SFU) - new study What happened to the seabirds?

11. Eradications Work only in specific cases Successful programs are often on small islands exotics removed: rats, cats, rabbits possum, goats, pigs Can have unexpected side effects release of other exotics

12. Biological Control the introduction of native enemies (predators, parasites, herbivores) to control an exotic species NATIVEEXOTIC CONTROLLED

13. Steps in Biological Control 1. Is the invasive an ecological or economic problem? If yes -------> 2 2. Is there sufficient support to initiate a biological control program If yes -------> 3 3. Understand basic biology identify weed, examine distribution identify natural enemiescontinue

14. Steps in Biological Control 4. Identify potential control agents 5. Test specificity of agents 6. Select effective agents one or many???

15. Biological control: a case study Diffuse Knapweed Pre-1930 Introduced via contaminated seeds 1940 Penticton, Oyama and Grand Forks 1970 Thompson and Okanagan Valleys Biological control started in 1972

16. Biological control of knapweed What control agents have been introduced? Total 12 insects and 1 fungus including 2 gall flies - Urophora spp 2 root boring weevils Sphenoptera Cyphocleonus 1 seed head weevil Larinus

17. Biological control of knapweed What happens after release of control agents? Before vs After or Treated vs Baseline Long term data from White Lake BC -J. Myers

18. Biological control of knapweed What happens after release of control agents? + Larinusmajor declines No Larinusno decline What about other agents? Low densities and low impact

19. How many agents are necessary? Several or one good one? Denoth et al 2002 - reviews 59 weed biocontrol studies

20. Biological control: case study 2 Purple loosestrife Displaces native plants Slows water flow Degrades wildlife habitat

21. Biological control of loosestrife Plant biomass % foliage removed Denoth and Myers 2005

22. Biological control Case study 3 The glassy-winged shooter Feeds on xylem from 250+ plant spp Eats 1-X body wt in liquids per hour

23. Biological control Case study 3 The glassy-winged shooter arrived in California in 1980 is a novel vector for a pathogen Xylella fastidosa that is costing wine industry millions and is moving North What do you do?

24. What actions and in what order?

25. Biological control of weeds/pests “is the only long term solution” Judy Myers BUT Biocontrol can and does go wrong

26. What can go wrong? Rhynocyllus on nodding thistle in BC Opuntia - Australia BeforeAfter Release of S American moth Cactoblastis Success---> introduction to Caribbean ----> natural spread to Florida Will it get to centres of cactus diversity????

27. Biological control - SUMMARY Can work May be only option BUT involves more exotics AND can have other effects Often 1 insect is sufficient Need to predict which one - HOW? and introduce as few spp as possible to minimise risk