W12: Biocontrol (Philosophy & History of Biocontrol) [Dr. Nic]

Question 1

Philosophy of biological control?

Answer 1

Resources are exploited by invasive species (space, nutrients & water), as seen in Indian mynas.

Question 2

Biotic interactions which we manipulate in biological control? (6)

Answer 2

• Mostly focus on predation.
• Interactions between predation and herbivory & predation and scavenging.
• Predation & herbivory via grazing of whole plants as we want plants to be eaten.
• Predation & scavenging via opportunistic scavenging/hunting.
• Biological control for plants = predation, herbivory & scavenging.
• Biological control for insects = parasitism.

Question 3

How does the biological control cycle work? (4)

Answer 3

• Agent provokes target.
• Target responds to the agent.
• Cycle continues.
• Depends on proven host specificity.

Question 4

History of biological control? (6)

Answer 4

• Started centuries ago.
• Essentially putting a cat on a ship to control the rats on it.
• Chinese citrus orchards have weaver ants to attack pests.
• Zulu cattle kraals have social spiders to eat pests that may attack cattle.
• More recent times with examples.
• The first intentional release was with the prickly pear.

Question 5

Egs of More recent times of Biological control? (2)

Answer 5

• Biocontrol of the fluted/cottony cushion scale circa using the vedalia beetle (agent).
• Biocontrol of the prickly pear using the cochineal (red dye was obtained from the acid of the cochineal) & cactus moth.

Question 6

Explain Eg of what not to do in Biological control? (2)

Answer 6

• Intentional introduction of the cane toad to eat cane beetles that were damaging sugar cane from Puerto Rico to Hawaii & Australia.
• Failed biological control, because there was no testing prior to introduction & host specificity, was not tested (toad was a generalist).