Biological Control

Question 1

What is biological control?

Answer 1

• The use of natural enemies to bring about reduction in the pest.
• Increases productivity of crops or decreases environmental degradation or disease
• Transfers of selected natural enemies from the home country of the pest

Question 2

Why does the pest and control organism have to remain in small numbers?

Answer 2

• Create balance of small number of pests and the control
• Total destruction of pest will cause eradication (elimination) of the control organism
• Undesirable because outbreaks of pests will recur

Question 3

What precaution must be taken before biological control?

Answer 3

• Must be carefully screened to ensure that the control is confined to the target pest
• Make sure the control species will not damage other plants and animals
• Numbers will dwindle as the pest reduces

Question 4

What are the advantages pf biological control?

Answer 4

• There are no harmful environmental side effects (each agent is restricted to one or more target species)
• Risks are known before release into the environment
• High benefit: cost ratios for successful programs
• Once agents are established, no further inputs needed

Question 5

Successful biological control programs

Answer 5

Prickly pear brought to Australia as an ornamental plant. - 1920s cactus invaded agricultural land
- Successful controlled by caterpillar of an Argentinian moth
Rabbits

Question 6

Unsuccessful biological control programs

Answer 6

Cane toad used to control cane beetle which attacks the growing shoots of sugarcane.

• Cane toad was a successful competitor of native species (causing their extinction and rare nature)
• Cane toads claimed their insect diet

Question 7

What other non-pesticide methods are used to control pests?

Answer 7

• The release of sterilised male pest insects which mate with fertile females (no offspring is produced)
• Selective breeding or genetic engineering of resistant strains
• pheromone baits
• physical methods

Question 8

What is integrated pest control?

Answer 8

An integrated approach incorporates chemical control, biological control, host resistance and cultural/physical control to reduce damage by pests to a tolerable level.
Creates a balance between human need and environmental protection.

Question 9

What does the success of integrated pest control depend on?

Answer 9

• Knowledge of the life cycle of pest species (most vulnerable stage)
• Monitoring pest numbers (where and when a problem is likely to occur)
• Combining two or more control measures and cooperation between all stake holders (agriculturalists, health authorities and scientists)