Pests Plagues & Politics
Lecture 14
Biological Control
Controlling “Pest” Insects
Let’s Go Green
Key points:
Biological Control
• Describe two key arthropod classes of biocontrol
agents
• What are the constraints of biological control
• What are the advantages of biocontrol
• Give other non-insect biocontrol agents
The biggest enemy of an insect is another INSECT!!
Bio-control is the use of a pest insect’s natural insect
enemies for its control.
Bugs eat Bugs
1) As direct predators*
2) As parasites & parasitoids*
Predators:
Ladybird adult
Both are excellent predators
Ladybird larva
Photo’s: Ken Gray photo
collection, OSU
Asian weaver ant
One of the earliest known
insects as biocontrol agents
http://en.wikipedia.org/wiki/Weaver_ant
Mike Burgett
Predation: A true
bug,
lunching on
another true bug.
Parasitoids: A fly
parasitoid larva
emerging from the
host larva.
Photo’s: Ken Gray photo
collection, OSU
A carpenter bee
giving you the once-over
A carpenter bee larva that has
been parasitized by a wasp.
Polyembryony has taken
place
and the bee larva contains
many thousands of wasp
larva
Mike Burgett
Mike Burgett
Biological Control – Advantages*
•
•
•
•
•
Self-perpetuating
Pest specific
Density dependent
Cost effective
Environmentally compatible
Biological Control – Constraints*
• Not immediately effective (may take
years)
• Not eradicative (is this really a constraint?)
• Biocontrol agents unknown for many
pest species.
• Doesn’t always work
– Historically only one out of four attempts
has been successful
What makes an effective biocontrol “agent”??
•
•
•
•
High to complete prey specificity
Multivoltine with respect to target species
Well adapted to habitat of target species
Excellent searching ability
Lacewing
immature
at “lunch”
Photo’s: Ken Gray photo
collection, OSU
Classic Biological Control
“Control of an Exotic insect pest by the
introduction of its natural enemies”
•
•
•
•
•
foreign exploration
quarantine processing
mass propagation
field colonization (release)
evaluation of impact
100 successes in the past 100 years!!
Bugs on plants
Tyria jacobaeae, Cinnabar moth
http://en.wikipedia.org/wiki/Cinnabar_moth
Preventing predation and
enhancing biocontrol
Bright colors of larvae/adults
warning sign
http://en.wikipedia.org/wiki/Cinnabar_moth
http://ucce.ucdavis.edu/files/repositoryfiles/ca2404p12-63742.pdf
Tansy ragwort flea
beetle. Prevents plants
from flowering through
feeding. Introduced in
USA in 1969
In addition to Classic Biocontrol (bug vs.
bug), we also use*:
• Insect Pathogens
– Viruses - Japanese Beetle Milky Disease,
Nuclear Polyhedrosis Virus
– Bacteria - the classic Bacillus thuringiensis
– Microsporidians - against grasshoppers
– Entomopathogenic fungi
– Entomopathogenic nematodes
Japanese beetle
Bacillus popilae
http://www.biconet.com/biocontrol/bpopillae.html
http://www.hort.uconn.edu/ipm/homegrnd/htms/wgrbpics.htm
I don’t
feel so
good.
Moth larva infected with a Polyhedrosis virus
http://www.monarchlab.org/lab/research/topics/Enemies/Default.aspx
Key points on Biological Control
• Describe two key arthropod classes of biocontrol agents
• What are the constraints of biological control
• What are the advantages of biocontrol
• Give other non-insect biocontrol agents
Another true bug munching
on an aphid. - A direct
predator.
A “mule killer” - a wingless
parasitoid wasp - also
known as velvet ants.
Photo’s: Ken Gray photo
collection, OSU
Bye
Key points:
Biological Control
• Describe two key arthropod classes of biocontrol
agents
• What are the constraints of biological control
• What are the advantages of biocontrol
• Give other non-insect biocontrol agents