1. Pests Plagues & Politics Lecture 14
Biological Control
Controlling “Pest” Insects
Let’s Go Green

2. 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

3. Bugs eat Bugs 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*

4. Both are excellent predators
Ladybird adult
Both are excellent predators
Ladybird larva
Photo’s: Ken Gray photo collection, OSU

5. Asian weaver ant One of the earliest known insects as biocontrol agents

6. Mike Burgett

7. Parasitoids: A fly parasitoid larva emerging from the host larva.
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

8. giving you the once-over
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

9. Mike Burgett

10. Biological Control – Advantages*
Self-perpetuating
Pest specific
Density dependent
Cost effective
Environmentally compatible

11. 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

12. 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

13. Classic Biological Control. “Control of an Exotic insect pest by the
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!!

14. Bugs on plants Tyria jacobaeae, Cinnabar moth

15. Preventing predation and enhancing biocontrol
Tansy ragwort flea beetle. Prevents plants from flowering through feeding. Introduced in USA in 1969
Bright colors of larvae/adults warning sign

16. 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

17. Japanese beetle Bacillus popilae

18. Moth larva infected with a Polyhedrosis virus
I don’t
feel so
good.
Moth larva infected with a Polyhedrosis virus

19. 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

20. Another true bug munching on an aphid. - A direct predator.
Bye
A “mule killer” - a wingless
parasitoid wasp - also
known as velvet ants.
Photo’s: Ken Gray photo collection, OSU

21. 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