applied population ecology - biological control of weeds
TRANSCRIPT
Applied population Ecology - Biological Control of Weeds and Insects
Judith Myers University of British Columbia Vancouver BC
The flora and fauna of the world are being
homogenized
Mexico ndash 23000 species of plants
700 species introduced
180 species invasiveF J Espinosa-Garciacutea J L Villasentildeor 2017 Revista Mexicana de Biodiversidad Volume 88 Supplement 1
What is an invasive species
An introduced species that becomes established spreads and has a negative
impact ndash about 10 of introduced species
Water hyacinth
Japanese beetle
Populations of invasive species tend to be higher in introduced range than in native range and become
serious pests
What can invasive species tell us about
population ecology
Ecological question ndash What controls
population density - Plants
Top down
Bottom up
Predators and parasitoids
reduce herbivores and thus
the world is greenSoil quality
Plant quality
Natural
enemies
Hairston Smith and Slobodkin 1967
Greenworld hypothesis
Predictions
Plants without herbivores would be large
and dense (Introduced plants)
Adding herbivores would reduce plant
density (Biological control)
How to test this
Species are invasive because they
lack natural enemies in
non-native (introduced) habitats
Top down control
Enemy release hypothesis
Ryan M Keane and Michael J Crawley 2002 TRENDS in Ecology amp Evolution 17 164-170
Testing the Enemy Release Hypothesis
Compare
1 Performance of introduced species with and
without natural enemies
2 Performance in native vs invaded habitat
3 Fewer natural enemies in invaded habitat
Heger T J M Jeschke 2014 Oikos 123741-750
Heger and Jeschke reviewed 176 studies that test if the
absence of enemies is related to invasion success
Number of natural enemies in native vs
introduced ranges
Organisms have fewer natural enemies in
introduced habitats
All aspects of the enemy release hypothesis
In the invasive range
1 Number of natural enemies less
2 Increased density of invasive
species
3 Performance of invasive reduced by
introduced natural enemies
36
Ecological question ndash What controls
population density
Top down
Bottom up
Top down control in less than
50 of studies as evidenced by
enemy release
However-
Most studies on plants
No studies on insects or
mammalsSoil quality
Plant quality
Natural
enemies
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
The flora and fauna of the world are being
homogenized
Mexico ndash 23000 species of plants
700 species introduced
180 species invasiveF J Espinosa-Garciacutea J L Villasentildeor 2017 Revista Mexicana de Biodiversidad Volume 88 Supplement 1
What is an invasive species
An introduced species that becomes established spreads and has a negative
impact ndash about 10 of introduced species
Water hyacinth
Japanese beetle
Populations of invasive species tend to be higher in introduced range than in native range and become
serious pests
What can invasive species tell us about
population ecology
Ecological question ndash What controls
population density - Plants
Top down
Bottom up
Predators and parasitoids
reduce herbivores and thus
the world is greenSoil quality
Plant quality
Natural
enemies
Hairston Smith and Slobodkin 1967
Greenworld hypothesis
Predictions
Plants without herbivores would be large
and dense (Introduced plants)
Adding herbivores would reduce plant
density (Biological control)
How to test this
Species are invasive because they
lack natural enemies in
non-native (introduced) habitats
Top down control
Enemy release hypothesis
Ryan M Keane and Michael J Crawley 2002 TRENDS in Ecology amp Evolution 17 164-170
Testing the Enemy Release Hypothesis
Compare
1 Performance of introduced species with and
without natural enemies
2 Performance in native vs invaded habitat
3 Fewer natural enemies in invaded habitat
Heger T J M Jeschke 2014 Oikos 123741-750
Heger and Jeschke reviewed 176 studies that test if the
absence of enemies is related to invasion success
Number of natural enemies in native vs
introduced ranges
Organisms have fewer natural enemies in
introduced habitats
All aspects of the enemy release hypothesis
In the invasive range
1 Number of natural enemies less
2 Increased density of invasive
species
3 Performance of invasive reduced by
introduced natural enemies
36
Ecological question ndash What controls
population density
Top down
Bottom up
Top down control in less than
50 of studies as evidenced by
enemy release
However-
Most studies on plants
No studies on insects or
mammalsSoil quality
Plant quality
Natural
enemies
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
What is an invasive species
An introduced species that becomes established spreads and has a negative
impact ndash about 10 of introduced species
Water hyacinth
Japanese beetle
Populations of invasive species tend to be higher in introduced range than in native range and become
serious pests
What can invasive species tell us about
population ecology
Ecological question ndash What controls
population density - Plants
Top down
Bottom up
Predators and parasitoids
reduce herbivores and thus
the world is greenSoil quality
Plant quality
Natural
enemies
Hairston Smith and Slobodkin 1967
Greenworld hypothesis
Predictions
Plants without herbivores would be large
and dense (Introduced plants)
Adding herbivores would reduce plant
density (Biological control)
How to test this
Species are invasive because they
lack natural enemies in
non-native (introduced) habitats
Top down control
Enemy release hypothesis
Ryan M Keane and Michael J Crawley 2002 TRENDS in Ecology amp Evolution 17 164-170
Testing the Enemy Release Hypothesis
Compare
1 Performance of introduced species with and
without natural enemies
2 Performance in native vs invaded habitat
3 Fewer natural enemies in invaded habitat
Heger T J M Jeschke 2014 Oikos 123741-750
Heger and Jeschke reviewed 176 studies that test if the
absence of enemies is related to invasion success
Number of natural enemies in native vs
introduced ranges
Organisms have fewer natural enemies in
introduced habitats
All aspects of the enemy release hypothesis
In the invasive range
1 Number of natural enemies less
2 Increased density of invasive
species
3 Performance of invasive reduced by
introduced natural enemies
36
Ecological question ndash What controls
population density
Top down
Bottom up
Top down control in less than
50 of studies as evidenced by
enemy release
However-
Most studies on plants
No studies on insects or
mammalsSoil quality
Plant quality
Natural
enemies
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Populations of invasive species tend to be higher in introduced range than in native range and become
serious pests
What can invasive species tell us about
population ecology
Ecological question ndash What controls
population density - Plants
Top down
Bottom up
Predators and parasitoids
reduce herbivores and thus
the world is greenSoil quality
Plant quality
Natural
enemies
Hairston Smith and Slobodkin 1967
Greenworld hypothesis
Predictions
Plants without herbivores would be large
and dense (Introduced plants)
Adding herbivores would reduce plant
density (Biological control)
How to test this
Species are invasive because they
lack natural enemies in
non-native (introduced) habitats
Top down control
Enemy release hypothesis
Ryan M Keane and Michael J Crawley 2002 TRENDS in Ecology amp Evolution 17 164-170
Testing the Enemy Release Hypothesis
Compare
1 Performance of introduced species with and
without natural enemies
2 Performance in native vs invaded habitat
3 Fewer natural enemies in invaded habitat
Heger T J M Jeschke 2014 Oikos 123741-750
Heger and Jeschke reviewed 176 studies that test if the
absence of enemies is related to invasion success
Number of natural enemies in native vs
introduced ranges
Organisms have fewer natural enemies in
introduced habitats
All aspects of the enemy release hypothesis
In the invasive range
1 Number of natural enemies less
2 Increased density of invasive
species
3 Performance of invasive reduced by
introduced natural enemies
36
Ecological question ndash What controls
population density
Top down
Bottom up
Top down control in less than
50 of studies as evidenced by
enemy release
However-
Most studies on plants
No studies on insects or
mammalsSoil quality
Plant quality
Natural
enemies
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Ecological question ndash What controls
population density - Plants
Top down
Bottom up
Predators and parasitoids
reduce herbivores and thus
the world is greenSoil quality
Plant quality
Natural
enemies
Hairston Smith and Slobodkin 1967
Greenworld hypothesis
Predictions
Plants without herbivores would be large
and dense (Introduced plants)
Adding herbivores would reduce plant
density (Biological control)
How to test this
Species are invasive because they
lack natural enemies in
non-native (introduced) habitats
Top down control
Enemy release hypothesis
Ryan M Keane and Michael J Crawley 2002 TRENDS in Ecology amp Evolution 17 164-170
Testing the Enemy Release Hypothesis
Compare
1 Performance of introduced species with and
without natural enemies
2 Performance in native vs invaded habitat
3 Fewer natural enemies in invaded habitat
Heger T J M Jeschke 2014 Oikos 123741-750
Heger and Jeschke reviewed 176 studies that test if the
absence of enemies is related to invasion success
Number of natural enemies in native vs
introduced ranges
Organisms have fewer natural enemies in
introduced habitats
All aspects of the enemy release hypothesis
In the invasive range
1 Number of natural enemies less
2 Increased density of invasive
species
3 Performance of invasive reduced by
introduced natural enemies
36
Ecological question ndash What controls
population density
Top down
Bottom up
Top down control in less than
50 of studies as evidenced by
enemy release
However-
Most studies on plants
No studies on insects or
mammalsSoil quality
Plant quality
Natural
enemies
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Predictions
Plants without herbivores would be large
and dense (Introduced plants)
Adding herbivores would reduce plant
density (Biological control)
How to test this
Species are invasive because they
lack natural enemies in
non-native (introduced) habitats
Top down control
Enemy release hypothesis
Ryan M Keane and Michael J Crawley 2002 TRENDS in Ecology amp Evolution 17 164-170
Testing the Enemy Release Hypothesis
Compare
1 Performance of introduced species with and
without natural enemies
2 Performance in native vs invaded habitat
3 Fewer natural enemies in invaded habitat
Heger T J M Jeschke 2014 Oikos 123741-750
Heger and Jeschke reviewed 176 studies that test if the
absence of enemies is related to invasion success
Number of natural enemies in native vs
introduced ranges
Organisms have fewer natural enemies in
introduced habitats
All aspects of the enemy release hypothesis
In the invasive range
1 Number of natural enemies less
2 Increased density of invasive
species
3 Performance of invasive reduced by
introduced natural enemies
36
Ecological question ndash What controls
population density
Top down
Bottom up
Top down control in less than
50 of studies as evidenced by
enemy release
However-
Most studies on plants
No studies on insects or
mammalsSoil quality
Plant quality
Natural
enemies
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Species are invasive because they
lack natural enemies in
non-native (introduced) habitats
Top down control
Enemy release hypothesis
Ryan M Keane and Michael J Crawley 2002 TRENDS in Ecology amp Evolution 17 164-170
Testing the Enemy Release Hypothesis
Compare
1 Performance of introduced species with and
without natural enemies
2 Performance in native vs invaded habitat
3 Fewer natural enemies in invaded habitat
Heger T J M Jeschke 2014 Oikos 123741-750
Heger and Jeschke reviewed 176 studies that test if the
absence of enemies is related to invasion success
Number of natural enemies in native vs
introduced ranges
Organisms have fewer natural enemies in
introduced habitats
All aspects of the enemy release hypothesis
In the invasive range
1 Number of natural enemies less
2 Increased density of invasive
species
3 Performance of invasive reduced by
introduced natural enemies
36
Ecological question ndash What controls
population density
Top down
Bottom up
Top down control in less than
50 of studies as evidenced by
enemy release
However-
Most studies on plants
No studies on insects or
mammalsSoil quality
Plant quality
Natural
enemies
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Testing the Enemy Release Hypothesis
Compare
1 Performance of introduced species with and
without natural enemies
2 Performance in native vs invaded habitat
3 Fewer natural enemies in invaded habitat
Heger T J M Jeschke 2014 Oikos 123741-750
Heger and Jeschke reviewed 176 studies that test if the
absence of enemies is related to invasion success
Number of natural enemies in native vs
introduced ranges
Organisms have fewer natural enemies in
introduced habitats
All aspects of the enemy release hypothesis
In the invasive range
1 Number of natural enemies less
2 Increased density of invasive
species
3 Performance of invasive reduced by
introduced natural enemies
36
Ecological question ndash What controls
population density
Top down
Bottom up
Top down control in less than
50 of studies as evidenced by
enemy release
However-
Most studies on plants
No studies on insects or
mammalsSoil quality
Plant quality
Natural
enemies
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Number of natural enemies in native vs
introduced ranges
Organisms have fewer natural enemies in
introduced habitats
All aspects of the enemy release hypothesis
In the invasive range
1 Number of natural enemies less
2 Increased density of invasive
species
3 Performance of invasive reduced by
introduced natural enemies
36
Ecological question ndash What controls
population density
Top down
Bottom up
Top down control in less than
50 of studies as evidenced by
enemy release
However-
Most studies on plants
No studies on insects or
mammalsSoil quality
Plant quality
Natural
enemies
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
All aspects of the enemy release hypothesis
In the invasive range
1 Number of natural enemies less
2 Increased density of invasive
species
3 Performance of invasive reduced by
introduced natural enemies
36
Ecological question ndash What controls
population density
Top down
Bottom up
Top down control in less than
50 of studies as evidenced by
enemy release
However-
Most studies on plants
No studies on insects or
mammalsSoil quality
Plant quality
Natural
enemies
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Ecological question ndash What controls
population density
Top down
Bottom up
Top down control in less than
50 of studies as evidenced by
enemy release
However-
Most studies on plants
No studies on insects or
mammalsSoil quality
Plant quality
Natural
enemies
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Testing the impact of top down control
Biological control - Introduce natural enemies from
the native range of the invasive species
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Biological control is experimental ecology
Do insect herbivores limit plant densities
Do predators or parasitoids reduce invasive
insects
Do introduced agents limit or regulate
invasive pests
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
How successful is biological control of weeds
successful programs
(Fowler 2000 ) (Suckling 2013 )(Culliney 2005)
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Biological control - Successes
In approximately 60 of programs introducing biological
control agents on weeds has been successful
Support for top down control of plants
Letrsquos look at an example
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Serious rangeland weed
Invasive
Potential
Native
Diffuse Knapweed(Centaurea diffusa)
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
12 species of agents were introduced for biological control of knapweed ndash 4 common
Gall fly Urophora affinis
Knapweed weevil Larinus minutus
Knapweed root borerSphenoptera jugoslavica
Knapweed root weevil Cyphocleonus achates
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Success with last species introduced in 1990rsquos
Knapweed Weevil (Larinus minutus)
Copyright copy 2017 Chris Joll
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Weevils reach high density and kill plants
Dead
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Plant density declined following weevil attack
Myers Jackson Quinn White
and Cory 2009 Biological Control
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Successful biological control -Top down control
Only some insect herbivores successful
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
What about insect populations
Is there evidence for top down control
Top down
Bottom up
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Some insect populations are are rare some
outbreak and some are cyclic
Western tent caterpillar(Malacosoma californica)
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Regulation - prevents unlimited increase
Average
Limitation
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Population ecology of Winter moth (Operophtera bruceata) ndash
Native to Europe
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Classic population study by Varley and Gradwell 1967 in England
Years
Larval counts
Lo
g la
rva
l d
en
sity
Varley y Gradwell 1967
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Winter moth - Introduced to Canada from Europe -
Adults emerge in November
Wikipedia
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Eggs hatch in early spring
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Larvae feed on a variety of
deciduous trees - oaks birch
blueberry apple heather
and Sitka spruce
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Leaves can be
damaged before
they have expanded
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Larvae balloon to
look for food
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Larvae drop to the
soil to pupate in late
May
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Monitored what kills larvae
Life table studies - England
Overwinter
loss
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Eggs
Fly
Parasitoids
Larvae
Beetle predators
Wasp
parasitoids
Moths
Pupae
Months
Life cycle
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Total mortality
From eggs to dropping larvae
December to June
Beetle predation on pupae
July to November
Wasp parasitism
July to November
Causes of mortality
Fly parasitism
March to June
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Pupal predation
k1Winter disappearance
Lo
g a
mo
un
t o
f d
ea
th
Pupal predation
Log larval density
k1Winter disappearance
Lo
g a
mo
un
t of d
ea
th
Winter disappearance from eggs to dropping larvae
Relation of mortality to density
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Conclusions
Fly parasitoids cause little mortality
Predation of pupae related to density
Winter disappearance highest
mortality and not related to density
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Winter moth becomes a pest in Canada
Should Cyzenis flies be introduced as a
biological control agent
An Experiment
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Many ground beetles already accidentally
introduced to Canada
David Ingram iNaturalistVictoria Natural History
Ground predators not able to reduce
introduced winter moth
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Cyzenis introduced
-05
0
05
1
15
2
1980 1982 1984 1986 1988 1990
Victoria BC
Lo
g10
Win
ter
mo
th d
en
sit
y
Winter moth decline after fly parasitoids
introduced to Canada
J Roland 1983 Journal of Animal Ecology
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Winter moth with biological control in
Canada - What happened over time
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Winter moth with biological control in Canada
J Roland 1994 J of Animal Ecology
Parasitoids
introduced
Predators
Density pupae m2
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Parasitoid reduced
(limited) the population
Predators regulated
the population
Winter moth in Canada
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Parasitoids and predators limit and regulate density
But what about bottom up influences
Top down
Bottom up
Wikipedia
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
What causes the mortality from egg hatch to
dropping larvae
k1
Lo
g a
mo
un
t o
f d
ea
th
Log larval density
Not related to density
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
What causes most mortality from egg hatch
to dropping larvae
Hunter Varley and Gradwell 1997 PNAS
Buds available
Buds delayed
Early egg
hatch
Ballooning
by early
larvae
Larv
ae p
er
48 leaf
clu
ste
rs
Days to 50 budburst
R2 = 076 Plt001
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Winter moth population variance explained
Hunter Varley and Gradwell 1997 PNAS
Top down 342
Bottom up 172
Unexplained 486Wikipedia
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Success of Biological control of invasive
insects with predators and parasitoids
Establishment (n) Success (n)
391 (3013) 172 (3013)
Heimpel GE Mills NJ (2017) Biological control ecology andapplications Cambridge University Press Cambridge
Is top down control less for insects
than plants
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
1 Parasitoid with little impact in native habitat
can reduce host density in introduced
habitat
2 Specialist parasitoid limited winter moth
population and generalist predators
regulated the population
3 Spring temperature variation influenced leaf
availability and larval survival
Summary
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Grab your pencils for the conclusions
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
1 Introduced and invasive species are serious pests
2 Top down control through biological control can
reduce population densities
3 Some natural enemies regulate (density dependent)
some limit populations and some have little impact
on target species
4 Phenology of budburst can influence herbivore
density ndash climate warming
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
1 Studying the population ecology of invasive species
gives direction to their control
2 Unpredictable what agents will be successful
3 Biological control is a potential aid in dealing with
invasive species
4 Biological control is experimental ecology
The future
Thanks
Thanks