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 Bugs

1) 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

Mike Burgett

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

Mike Burgett

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!!

Tyria jacobaeae, Cinnabar moth

Bugs on plants

http://en.wikipedia.org/wiki/Cinnabar_moth

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

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