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Pests Plagues & Politics
Lecture 14
Biological Control
Controlling “Pest” InsectsLetLet’’s Go 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 BugsBugs eat Bugs1) As direct 1) As direct predators*predators*
2) As 2) As parasitesparasites & & parasitoids*parasitoids*
Predators:
Ladybird adult
Ladybird larva
Both are excellent predators
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
Predation: A true Predation: A true bug, bug, lunching onlunching onanother true buganother true bug.
Photo’s: Ken Gray photo collection, OSU
Parasitoids: A fly Parasitoids: A fly parasitoidparasitoid larva larva emerging from the emerging from the host larva.host larva.
A carpenter beegiving you the once-over
A carpenter bee larva that hasbeen parasitized by a wasp.
Mike Burgett
Polyembryony has taken place
and the bee larva containsmany thousands of wasp
larva
Biological Control – Advantages*Biological Control – Advantages*
• Self-perpetuatingSelf-perpetuating• Pest specificPest specific• Density dependentDensity dependent• Cost effectiveCost effective• Environmentally compatibleEnvironmentally compatible
Biological Control – Constraints*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
Lacewingimmatureat “lunch”
Photo’s: Ken Gray photo collection, OSU
Classic Biological ControlClassic 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!!100 successes in the past 100 years!!
Bright colors of larvae/adults warning sign
Tansy ragwort flea beetle. Prevents plants from flowering through feeding. Introduced in USA in 1969
Preventing predation and enhancing biocontrol
http://en.wikipedia.org/wiki/Cinnabar_moth
http://ucce.ucdavis.edu/files/repositoryfiles/ca2404p12-63742.pdf
In addition to Classic Biocontrol (bug vs. In addition to Classic Biocontrol (bug vs. bug), we also use*:bug), we also use*:
• Insect Pathogens– VirusesViruses - Japanese Beetle Milky Disease,
Nuclear Polyhedrosis Virus– BacteriaBacteria - the classic Bacillus thuringiensis– MicrosporidiansMicrosporidians - against grasshoppers– EntomopathogenicEntomopathogenic fungifungi– Entomopathogenic nematodesEntomopathogenic nematodes
Japanese beetle
Bacillus popilaehttp://www.biconet.com/biocontrol/bpopillae.html
http://www.hort.uconn.edu/ipm/homegrnd/htms/wgrbpics.htm
Moth larva infected with a Polyhedrosis virusMoth larva infected with a Polyhedrosis virus
I donI don’’ttfeel so feel so good.good.
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 munchingon an aphid. - A directpredator.
A “mule killer” - a winglessparasitoid wasp - alsoknown as velvet ants.
ByeBye
Photo’s: Ken Gray photo collection, OSU