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

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*

Both are excellent 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

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

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

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 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 Tansy ragwort flea beetle. Prevents plants from flowering through feeding. Introduced in USA in 1969 Bright colors of larvae/adults warning sign http://en.wikipedia.org/wiki/Cinnabar_moth http://ucce.ucdavis.edu/files/repositoryfiles/ca2404p12-63742.pdf

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

Moth larva infected with a Polyhedrosis virus 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. Bye A “mule killer” - a wingless parasitoid wasp - also known as velvet ants. 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