Unit 1 –
Introduction to Invasive
Alien Species –
Overview of the Problem
Randy G. Westbrooks
Rebecca M. Westbrooks
Steven Manning
Global Invasive Species Programme
Cape Town, South Africa
Unit Objectives
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Understand and describe the nature of the IAS problem
List some of the major characteristics of IAS
Discuss a few of the world’s worst IAS
Discuss the basic ecological, economic and public health
impacts of IAS
Describe the process of biological invasions
Give examples of intentional and unintentional introductions
List major pathways and vectors of primary and secondary
spread
Explain difficulties with predicting invasiveness of organisms
Discuss some of the factors that are enhancing the global
spread of IAS
Session Outline and Agenda
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1100-1125. Session 1. Introduction to Invasive Alien Species.
1125-1145. Session 2. Human Facilitated Spread of Plants and
Animals – “Who’s Using Who?”
1145 – 1200. Lab Exercise.
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1200 – 1300. Lunch.
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1300-1330. Session 3. Predicting Invasiveness – Forewarned Is
Forearmed!
1330-1400. Session 4. Factors Enhancing the Spread of IAS.
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1400-1445. Lab Exercises.
1445-1450. Review of Major Concepts in Unit 1.
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1450-1500. Break.
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Session 1. Introduction to IAS.
1.1. Overview of the Problem.
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Crop Pests – Historic Struggle
Between Man and Nature
Invasive Alien Species (IAS) –
Plants/Animals Outside their Native
Range – Due to Trade and Travel
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Ecological Impacts – Hydrology,
Sediments, Soil & Water Chemistry,
Disruption of Fire Cycles
Economic and Social Losses - $300+
Billion Globally, Deplete Water Supplies,
Famine/Disease, Grazing Lands, Noise
Pollution
Ports of Entry – First Line of
Defense Against IAS
1.1.2. IAS - Ecosystems out of Balance
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Origin of IAS
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Remove Top
Predators
Insert New Exotic
Species Without
Co-Evolved
Predators and
Parasites
Food Web
Beaver
Simple Food Chain
Eastern Gray
Squirrel
1.1.3. Evolution in Isolation –
Recreation of a Virtual Pangaea
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Super-continents
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Evolution in Isolation
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Columbia 1.5 Billion Yr BP
Rodinia 700 Million BP
Pangaea 180 Million Yr BP
Ecological Explosion
8,600 Birds (4X #)
Global Spread of IAS
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Recreating a Virtual Pangaea
Homogeocene
Pangaea
1.2. Characteristics of IAS.
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Abundant in Natural Range
History of Invasiveness Outside Natural Range
Wide Distribution in Different Habitats
Fast Growth, Early Maturity
High Reproduction; Seed Dormancy
Allelopathy
Prickles, Spines, Thorns
Parasitism
Same Size/Shape as Crop Seeds
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Ability to Go without Food/Water
Roots/Rhizomes with Large Storage
Efficient Means of Spread
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Close Association with Humans
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Purple nutsedge (Cyperus
rotundus) – the perfect weed.
1.3. Characteristics of Invaded Habitats.
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Ecological Similarities
Between Origin and
Receiving Ecosystems
Lack of Co-evolved
Predators and Parasites
Other IAS already
A
Established
High Degree of
Disturbance
Secondary Pathways and
Vectors for Further Spread
B
A. Wet Tropics of Queensland, Australia. B.
Florida Everglades, United States.
1.4. Overview of IAS Taxa Groups.
Invasive Plants,
Insects, Diseases,
Aquatic Nuisance
Species, and
Injurious Wildlife.
1.4.1. Invasive Plants.
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250,000 Plants in the World
22,000 Invasive Plants
Definitions
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Invasive Plant = Weed
Noxious Weed = Regulated
Weed
Melaleuca and Pond Apple –
Tale of Two Weeds in North
America and Australia
Melaleuca
Pond Apple
1.4.2. Insects.
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30 Million Insect Species
500,000 Species of Beetles
Desert Locust
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Africa, Middle East, Asia
Swarms –
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1,200 km2
96 Billion Individuals
240,000 Metric Tons
Losses
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Morocco – 1954 ($50 Million in
6 Weeks)
Ethiopia – 1958 (167,000 Tons
of Grain – Feed 1 Million
People for a Year
Mauritania, July, 1994
1.4.3. Aquatic Nuisance Species.
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ANS Factoids
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21 Billion Gallons
Ballast Water Per Year (USA)
3,000 ANS Moving in
Ballast Water Around
the World
ANS Taxa
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Aquatic Weeds (Water
Hyacinth)
Aquatic Invertebrates
(Zebra Mussel)
Aquatic Vertebrates
(Nile Perch)
1.44. Injurious Wildlife
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Terrestrial Vertebrates
Intentionally Established
 Game Animals
 Domestic Animals
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IW Examples
Nutria
 Eastern Gray Squirrel
 Australian Brushtail Possum
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1.5.1. Ecological Impacts of IAS.
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Threaten Endangered
Species
Crowd out Natives
Compete with Natives for
Resources, Space, Light
Disrupt Trophic Level
Relationships
Increase Disturbance
Regimes that Natives are not
Adapted to (e.g., Wildfires)
Hybridize with Natives
Cause Habitat Loss
Fynbos – South Africa
Argentine Ant
Old World Climbing Fern in Florida
Cheatgrass in the American West
Mallard Duck
1.52. Economic Effects of IAS.
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USA:
$150 Billion
India:
US$117 Billion
South Africa:
US$17.5 Billion
United Kingdom:
US$12 Billion
Australia:
AUS$10 Billion
New Zealand:
US$10 Billion
Africa (Aquatic Weed Control): $US60 Million
1.5.2.2. Economic Impacts of IAS.
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Direct Losses
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Crop Losses (India – 20% Per
Year)
Loss of Exports
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Loss of Pasture Productivity
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Cogongrass
Loss of Fisheries
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Karnal Bunt of Wheat
Nile Perch
Indirect Losses
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Flooding (Water Hyacinth)
Landslides (Miconia)
Damage to Dams (Nutria)
Increased Wildfires
(Cheatgrass)
Loss of Tourism (Spotted
Knapweed)
1.53. Public Health Impacts.
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Diseases
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1999 - West Nile Virus USA
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9,862 People Infected
264 People Died
2003 SARS in China
$17 Billion Tourism Losses
Stings - Allergic
Reactions
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Imported Red Fire Ant
Africanized Honey Bee
Session 2. Spread of Plants and Animals
– Who’s Using Who?
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Reversion of
Cultivars to Wild
Forms
Olives
 Granny Smith
Apple
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1.6. Process of Invasion.
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Primary Introduction
Establishment
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Monterey Pine in NZ,
AUS
Secondary Spread
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Vehicles, Trains,
Trailers, Animals
1.6.2. The IAS Lag Phase.
Melaleuca in the Florida Everglades.
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Florida Everglades
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River of Grass, Tree Islands
80 Miles wide, 1/3 M Deep
1906 – Introduced from AUS
1936 - Aerial Seeding with
Melaleuca
1970s – Rapid Spread
throughout the Glades
1990s – 200,000 ha Infested
1.7. Intentional Introductions.
1.7.1. Introductions that become Invasive.
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Agricultural Crops
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Forestry Species
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Cordia - Vanuatu
Ornamental Plants
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Kudzu - USA
Aid Trade
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Leucaena - Africa
Erosion Control
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Tall Fescue - Pastures
Siam Weed - Africa
Germplasm
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Disease Infected
Wheat
1.7. Intentional Introductions.
1.7.1. Introductions that become Invasive.
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Game Animals
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Mammals as Food
Source on Islands
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Nile Perch – Lake
Victoria, Africa
Pets Released in Wild
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Cane Toad - AUS
Fishery Releases
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Feral Pigs, Goats
Biocontrol Agents
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Sika Deer - USA
Burmese Python - USA
Aquaculture Escapes
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LA Crayfish - Africa
1.7.1.2. Unauthorized Intentional
Introductions (Smuggling).
Chinese Water Spinach
(Ipomoea aquatica)
1.8. Unintentional Introductions.
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Adaptations for Spread
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Stowaways
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Khapra Beetle
Hitchhikers
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Plants – Burs (Cocklebur),
Seed Sails, Floating Seeds
Animals – Dog Tick
Snails
Khapra beetle
Contaminants (Comingled)
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Weed Seed in Crop Seed
Jointed Goatgrass in Wheat
1.8. Unintentional Introductions. Contd.
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Hitchhikers on Nursery
Plants
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Hitchhikers on Cut
Flowers
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Crazy Yellow Ant
Ballast Soil and Water
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Giant African Snail
Mail
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Clemora smithi (Sugarcane White
Grub) Transferred from
Barbados to Mauritius in
Sugarcane
Planes, Trains, Vehicles,
Equipment
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Leaf Miners
Soil Pests
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Pink Hibiscus Mealybug
Chinese Mitten Crab
Hull Fouling Organisms
Case Study: Yellow Crazy Ants on Christmas Island
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1930 – Introduced to
Christmas Island*
1990s – Population Exploded
Forms Multi-Queen Super
Colonies
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Up to 700 ha in Size
Overwhelms and Kills Native
Species
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Red Land Crabs
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1995-2002 - 10-20 Million Killed
Robber Crabs, Native Reptiles
Native Invertebrates
Control – Toxic Bait – 99%
Effective
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Fipronil in Fish Meal (0.6 gm/ha)
*1528 km NW of AUS; Possession of
AUS
1.8.1. Case Study: Serrated Tussock in the U.S.
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Description: Annual Grass
Origin: Argentina
Threat: Serious Pasture Weed,
Minimal Nutrient Value
Areas Affected: AUS, NZ
1989 Introduction to USA
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Nine Infested Shipments from ARG
Loophole in FNWA – Seed Shipments
Exempt from Regulation under the Law
Federal Judge Ruled Intent of Law
Included Seed Shipments
Results
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Large Amount Re-exported to Canada,
Japan
5,000 kg (11,000 lbs.) Burned in Kentucky
6,800 kg (15,000 lbs.) Buried in Landfill in
Missouri
Small Amount Hydroseeded onto
Stripmine Reclamation Sites in Kentucky
1.9.1. Pathways of Unintentional Spread.
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Commercial Shipping
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People Movers
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Ships
Planes
Trains
Vehicles – Trucks
Ships, Planes, Trains,
Vehicles
People
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Beggar-lice on
Trousers
1.9.2.2. Unintentional Spread by Cargo and
Commodities.
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Cargo – Wide Range
of Commercial Goods
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Military Equipment
Commodity –
Homogeneous
Substances in
Commerce
Imported Fruit
 Ornamental Rocks
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Unit 1 – Lab Exercise 1.
IAS in Participant Countries.
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1. Name five introduced species in your country
that are not considered to be invasive.
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2. Name five introduced species in your country
that are considered to be invasive.
Lunch!
Sponsored by:
Dr. Lynn Jackson
Global Invasive Species Programme
Capetown, South Africa
Session 3. Predicting Invasiveness.
1.10. Methods of Predicting Invasiveness.
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Criteria for IAS Prevention Program
 Know
About IAS Worldwide
 GISP:
 http://www.gisp.org/
 Global
Invasive Species Database:
 http://www.issg.org/database/welcome/
 Know
Which Ones Pose a Threat to Your
Country
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Characteristics of Ideal Invaders
Session 3. Predicting Invasiveness.
1.10. Characteristics of the Ideal Invader.
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Widespread in Native Range (Kudzu in
China)
History of Invasiveness Elsewhere
(Serrated Tussock in Australia)
Adapted in Wide Range of
Environments and Soils (Tropical Soda
Apple)
Rapid Growth and Maturity (Cactus
Moth)
Produces Many Offspring (Desert Locust)
Rapid Colonizer (Giant Salvinia)
Efficient Dispersal Mechanisms (Jointed
Goatgrass in Wheat)
Broad Diet (Coqui Frog)
Aggressive Behavior (Imported Fire Ant)
Close Relationship with Humans
(Oriental Cockroach)
Small in Size (Khapra Beetle)
April 5, 2005
July 13, 2005
Session 3. Predicting Invasiveness.
1.10. Susceptibility of Environments to Invasion.
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Similarities between Native
Range of IAS and Receiving
Region
IAS Already Established in the
Region
Level of Development and
Disturbance
Low Biodiversity Due to
Habitat Loss or Stressors such
as Over Grazing, Wildfires,
Clear Cutting, Water Pollution
Vectors for Secondary Spread
Isolated Communities with
High % Endemic Species
Session 3. Predicting Invasiveness.
1.10. IAS Risk Assessment.
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Regulatory Prevention Pest Risk Assessment Systems*.
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USDA APHIS Weed Risk Assessment System
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AUS AQIS Weed Risk Assessment System
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Prohibited Listing Approach
Permitted Listing Approach - 49 Questions
Score < 1 (Permitted Entry)
Score 1 – 6 (Evaluated Further)
Score > 6 (Prohibited Entry)
Ranking of Established IAS
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NatureServe I-Ranking (400 Species Ranked)
*More in Unit 7.
Session 4. Factors Enhancing Spread of IAS.
1.11. IAS and Globalization.
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The Global Village
Instant Communications
 Global Trade, Travel
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Homogenization of World’s Flora & Fauna
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Species Introductions – Social, Economic Reasons
The ‘Homogeocene’
Homogenizing the World’s Flora and
Fauna.........
Our Legacy?
The Great American Exchange
Panama Land Bridge, 3 Million Yr. BP
North American
Mammals
South American
Marsupials
Session 4. Factors Enhancing Spread of IAS.
1.12. IAS and Changing Land Use Patterns.
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Human Development and
Habitation - Civilization
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Nutrient Rich Urban Lawns
and Gardens (Chinese
Wisteria)
Higher # IAS Around
Population Centers
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Habitat Fragmentation,
Attract Wildlife, Attract IAS
Source Areas for Horticultural IAS
More People = More IAS
Purple Loosestrife – Campbell
Creek, Anchorage, Alaska
Roads and Highways
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Connecting People – Spreading IAS
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Japanese Hops, Connecticut, USA
Johnsongrass, North Carolina, USA
Dar es Salaam, Askari Monument
1.13. IAS and Global Climate Change.
Cause and Effect.
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Land Use Changes (Habitat Fragmentation
and Destruction)
Build up of Greenhouse Gases (Global
Warming, Sea Level Rise, Ecosystem Demise)
Air & Water Pollution (Threat to
Environmental/Human Health
Spread of Invasive Species (Threat to
Biodiversity and Agricultural Production)
Pleistocene Interglacial Periods.
Natural Climate Change Events in North America.
1.8 Million – 11,500 Years Ago.
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Average Temperature
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2-3o C Higher
Plants/Animals
Migrated North
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South American Tapirs
in North Carolina
Sweetgum in Canada
Manatees in New Jersey
Potential Impacts of Modern
Global Warming
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Temperatures
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Drought, Heat Waves
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Hurricane Katrina
Sea Level Rise
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Melting Glaciers
Melting Snowcaps
More Rainfall, Storms,
Hurricanes
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4-9o C Higher
0.4 - 0.5 m
Disturbance and Change…..
Mt. Kilimanjaro stripped of its snowcap
for the first time in 11,000 years.
Potential Impacts of Global Warming
on Natural Ecosystems.
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Disappearance of Sensitive Habitat
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Eastern Forests Changes
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Alpine Meadows
Mixed Woodlands and Grasslands
Northwestern Forests Lose Key Species over
Decades
Species Attempt to Migrate North…….
Species Migrations In Response to
Global Climate Change.
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Vegetation Zones Shift 300
km Towards the Poles
Loblolly Pine Distribution
Move 300 Miles Northward
Impediments to Species Migration.
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Climate Change Faster than
Species can Migrate (Trees
Migrate 20-30 km per Century)
Human Settlements, Activities,
Development, Highways
Invasive Species Move in to
Southern Boundary Transition
Zones
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Cogongrass in Alabama
Invasive Species
in a Warmer World
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Expand their Range, Invade New
Habitats
Compete with Stressed Natives
Create Synergistic Effects with
other Global Changes
Chinese Tallow Tree
(Triadica sebifera)
Human Induced Global Change
Cause and Effect
Invasive
Species
Habitat Burning
Land Use Destruction Fossil Air & Water
Fuels
Changes
Pollution
Invasive
Species
Elevated
Ecosystem
Break
Down
More Fires
Invasive
Species
Drought
Invasive
Species
Invasive
Species
CO2
Temperatures
Rise
More
Precipitation
Invasive
Sea Level Rise
Species
Unit 1 – Major Concepts.
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IAS have traits that permit them to outcompete native and
beneficial species.
IAS often invade areas that are very similar to their native
range.
Over 22,000 invasive plants have been documented.
Unlike chemical pollutants that breakdown, biological
pollutants multiply and spread.
Impact of IAS on Human Health – allergies, infectious
diseases, and Stings.
Phases of Biological Invasions - Introduction,
Establishment, and Spread.
The Lag Phase – a Biological Time Bomb.
The Precautionary Principle - Most effective way to
minimize further problems with IAS.
Unit 1 – Major Concepts, Contd.
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About 1% of all introduced plants will become
invasive.
About 75% of all invasive plants were intentionally
introduced.
Pathways of IAS spread -Commercial Shipping, Air,
Water, and Overland Travel, People
Unintentional Introductions - Cargo and Commodities
may become infested Stowaways and Contaminants at
the point of origin, or somewhere along the transport
to a new region.
Best Predictor of Invasiveness – A History of
Invasiveness Elsewhere.
Factors increasing the spread of IAS - Globalization,
Land Use Changes, and Global Climate Change.
Unit 1 – Lab Exercise 2.
Modeling Exponential Growth of Yellow Starthistle.
Year
Initial Seedbank
Seeds Introduced
into Seedbank =
Persistent
Seedbank
(Seeds that will
not Germinate
Right Away)
(96%)
Seedlings
(Seeds
that
Germinate
and
Become
Seedlings)
(4%)
Adult Plants
(Seedlings
that
will Survive to
Maturity)
(25%)
Next Year’s Seedbank
=
Persistent Seedbank
(SB) +
Seeds Produced This
Year (SP) =
(A)(1,000)
X
SB = (X)(0.96)
S = (X)(0.04)
A = (S)(0.25)
= SB + SP
0-1
2
3
4
5
6
100
1096
96
1050
4
46
1
10.96
1096
10,960
Unit 1. Exercise 3.
Pathways, Vectors, Introductions.

List major IAS at your port of entry (e.g., Ships, Planes, Vehicles, etc.).

List major IAS vectors and origins of introduced pests that pass through your
port (Types of Commodities, Ballast Water, etc.).

List one authorized intentionally introduced species that has become invasive in
your country. Why/when was it introduced? What impacts is it having?

List one unauthorized intentionally introduced species (smuggled) that has
become invasive in your country. Why/when was it introduced? What impacts
is it having?

List one unintentionally introduced species (stowaway, hitchhiker, or
contaminant) that has become established and invasive in your country. How
was it introduced (pathway, vector)? When was it introduced? What impacts is
it having?
Unit 1. Exercise 4.
IAS Risk Assessment.

List characteristics of successful invaders.

What kind of regulatory pest risk assessment
system does your country use (permitted listing
approach, prohibited listing approach).
Special Thanks:
Lynn Jackson and Philip Ivey
Global Invasive Species Programme,
Cape Town, South Africa
Janine Lloyd
USGS BRD, Whiteville, NC
Graphics, Lay Out, Design
Les Mehrhoff
University of Connecticut, Storrs, CT
– Editorial Review
White Sands Hotel and Resort
Jangwani Beach, Dar es Salaam, Tanzania