Objectives

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Objectives

• Definitions
• Examples
• Stages of Invasion
• Arrival - how?
• Establishment
• What characteristics?
• Spread
• Why successful?
• How impact native species?
• Why are some ecosystems more vulnerable?
• Control and Prevention

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Definitions

• Introduced (non-native, exotic)
• - species introduced deliberately or
  accidentally from
• somewhere else
• - more than 10,000 species in USA
• Domestic/Feral (released pets, livestock and
  game
• animals)
• - can spread disease, compete with
  native species
• Invasive species
• - species that spread subsequent to
  establishment
• usually at some cost.

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Vertebrates House Sparrow

• Introduced into
• Brooklyn, New York,
• in 1851.

• Competition from the House
• Sparrow for cavity nests can
• cause decline of some native
• species.

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Insects

• In 1956, African Honey Bees were imported into
  Brazil

• Africanized Bees

• In 1957, 26 African queens escaped

• Reached US in 1990

• More aggressive than European Honey Bees
• have killed 1,000 people

• Impact honey and pollination industries

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• Asian Long-horned Beetle
• attacks and kills many native trees

Found in Chicago in 1998
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• Gypsy moth

• Introduced in 1860s
• Originally brought to the US for silk production
• now defoliates entire forests

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Plants
Kudzu

• Introduced to U.S. in 1876 at the Philadelphia
  Centennial Exposition
• promoted as a forage
• crop and ornamental
• plant until 1953
• kills other plants by
• smothering them
• under a solid blanket
• of leaves

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Reptiles and Amphibians
Cane toad native to Central and South America

• Introduced world-wide to
• control insects (Australia)
• milky secretions are
• highly toxic. Kill dogs,
• cats and small native
• animals.

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Python Explodes After Eating Alligator October 5,
2005 MIAMI, (AP) Alligators have clashed with
nonnative pythons before in Everglades National
Park. But when a 6-foot gator tangled with a
13-foot python recently, the result wasnt
pretty. The snake apparently tried to swallow the
gator whole and then exploded. The gators
have had to share their territory with a python
population that has swelled over the past 20
years after owners dropped off pythons they no
longer wanted in the Everglades. The Asian snakes
have thrived in the wet, hot climate.
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Gastropods ZEBRA MUSSEL - Dreissena polymorpha

• Found in 1988 in Lake St. Clair (Lake between
  Huron and
• Erie, just off of Detroit, MI).

• Up to 70,000 individuals per m2
• Likely came to North America
• in ballast water

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• One of the most expensive exotic species

• Restricts the flow of water through intake
  pipes
• (drinking, cooling, processing and irrigating
  water)
• Attaches to boat hulls, docks, locks,
  breakwaters
• and navigation aids, increasing maintenance
  costs
• and impeding waterborne transport.

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Stages of invasion
1. Arrival
2. Establishment
3. Spread
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1. ARRIVAL

• Introduced deliberately
• naturalization societies
• Shakespeare fans
• game animals
• domestic animals

• Accidentally
• ballasts of ships
• unprocessed wood
• fruit shipments
• by-pass natural barriers

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1. Arrival Vectors of invasion into ecosystems

• A. Intentional Release of Target Species
• Plants for Agriculture
• Plants for Forestry
• Plants for Soil Improvements
• - fire suppression, erosion control
• Ornamental Plants
• Birds and Mammals for Hunting
• Biological Control
• Released Pets and Pet Trade

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1. ArrivalVectors of invasion into ecosystems

• Release of Non-Target Species (Accidental
  Releases)
• Contaminants or Hitchhikers with Produce
• Contaminants or Hitchhikers with Ornamental
  Plants
• Contaminants or Hitchhikers with Aquaculture
• Timber
• Contaminants of Seed Stock
• Cars
• Planes
• Hitchhikers with Packing Material, Cargo
• Ballast in ships
• Ship Hull Fouling
• Tourists, Luggage
• Canals

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Ballast Tanks
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1. Arrival Pathogens and Disease
Forecast and control of epidemics in a
globalized world. Hufnagel et al. PNAS 2004
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2. Establishment Characteristics of invasive
species

• general diet and habitat requirements
• high abundance
• small body size
• high reproductive potential (r-strategy)
• good competitors
• social / gregarious
• (different characteristics may be important at
• different stages)

Generalities would be nice! Make invasion biology
a predictive science.
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• Spread Hypotheses for the success
• of introduced species

• Escape from natural enemies
• predators, parasites, disease
• Increased competitive ability
• outcompete native species
• Pre-adapted to disturbed environments

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3. Spread How do they impact native species?

• Can be predators, competitors, parasites,
  diseases.
• Can modify habitat.
• Can promote spread of other invaders.
• Ultimatelydisplace native species

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• Percentage of threatened or endangered
• species imperiled by
• Habitat degradation and loss - 85
• Invasive species - 49
• Pollution - 24
• Overexploitation - 17
• Disease - 3

Source Wilcove et al.1998 BioScience
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The Invasive Argentine ant
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3. Spread Invasive replaces native through time

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• Phrynosoma coronatum
• Declining throughout
• its range.
• A sit and wait ant
• specialist.
• Doesnt eat Argentine ant.

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• Mechanisms responsible for invasion success
• in Argentine ants
• Escape from natural enemies
• predators and parasites.
• Pre-adapted to disturbed environments.
• Different competitive environment -
• competitive release.
• Increased competitive ability - increased
  density.

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Displacement or replacement?

• Homogenization
• Process by which a mixture is made uniform
  throughout.
• Biotic homogenization
• Increasing similarity in species among areas.
• Habitat loss and modification coupled with the
• widespread introduction of a few species leads
• to homogenization.

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3. Spread What makes certain ecosystems
vulnerable?

• Diverse, undisturbed ecosystems have few
  invaders
• Biotic resistance
• Disturbed habitats have more invaders
• Human residential areas
• many European species that are commensal
• with humans
• Islands little history with competitors,
  predators,
• parasites, or diseases

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Over 2,000 species of birds have gone extinct on
islands as a result of habitat loss and the
introduction of predators and parasites.
Hawaii Habitat loss, malaria, rats and mongoose
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Birds on islands (from Case 1996 Biol Con)
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Estimated annual costs associated with non-native
species Group costs (in
millions) Plants (purple loosestrife, weeds)
34,000 Mammals (feral pigs, rats)
37,000 Birds (pigeons, starlings)
2,000 Fishes
1,000 Arthropods (ants, termites, other pests)
19,000 Mollusks (zebra mussel, asian
clam) 1,200 Microbes (plant
pathogens, animal disease) 41,000 All
organisms over 136 billion per year
Source Pimentel et al. 2000 BioScience
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How do we control invasive species?

• In urban and agricultural areas
  pesticide/herbicide use still common
• Natural enemies - Biological Control
• Manage the landscape to minimize disturbance

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Results of pesticide use

• Killed native competitors
• May select for resistance
• Health risks for people

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• Biological Control
• The use of one species to control another.
• Usually a specialist predator or
• parasite of an invasive species.
• Needs to be species-specific or can cause
• even worse problems.

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Prevention

• Education is key
• Research is still needed - generalities?
• Monitoring programs - early detection
• Prevent establishment - quarantine
• Increased communication among agencies
• Increase regulations

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How can you stop the spread of exotics?
http//www.invasivespeciesinfo.gov/