Lecture 12 - New Control Methods for Pests and Diseases

Question 1

Differ between horizontal and vertical transmission of disease.

Answer 1

Horizontal transmission refers to transmission between individuals, or via vector or intermediate host.

Vertical transmission refers to inter-generational transmission.

Question 2

The rate of infected individuals is proportional to _____. (3)

Answer 2

probability of passing disease, effective average no. of contact, duration of infection

Question 3

Explain how spraying a thin film of oil may lead to the disruption in the mosquito life cycle.

Answer 3

Mosquito larvae requires air to breathe, through a tube held to the water surface by surface tension. By spraying the thin oil film, the surface tension is gone and mosquito dies.

Question 4

Mention the desirable features of predators.

Answer 4

• Specific prey/hosts (doesn ‘t interfere with other organisms).
• Same habitats as pest
• Rapid rate of increases
• Disperse easily
• Stable population
• Easily cultured

Question 5

Mention improved methods to spread genetic load.

Answer 5

• Delayed sterility
• Conditional lethal genes
• Meiotic drive: one of a pair of chromosomes goes into all the gametes
• using more sexually active male
• introducing an incompatible competing strain.

Question 6

Define genetic load.

Answer 6

the presence of unfavourable genetic material in the genes of a population.