Resistance To Chemical Control

Question 1

Reasons for development of resistance.

Answer 1

Reason for this trait is genetic.
Organism may have increased ability to metabolise toxic compounds - metabolic resistance
Organisms may have a reduced number of receptors to which the chemical binds - altered target resistance
In addition , behavioural changes may alter the likelihood of the pest coming into contact with the chemical. - behavioural resistance.
Some insects develop modified outer cuticle which slows the absorption of chemicals. - penetration resistance.

Resistance is most troublesome when organisms have rapid life cycles as these successful genetic adaptations are passed to a new generation within a short timescale and may become still further improved.

Question 2

Resistance developing among an insect population.

Answer 2

i) Small proportion of the population possesses resistance genes before chemical application.
ii)
Following applications chemical most susceptible insects die leaving resistant individuals.
iii) Resistant individuals breed and produce more resistant individuals.

Question 3

Resistance in peach-potato aphid and Two-spotted spider mite.

Answer 3

Cause -over reliance in pesticides.
Applying same insecticide with known mode of action continuously.
Solution - cultural controls, biological controls when using chemical alternate and make sure that the chemicals act in different always.

Question 4

Resistance in Rose Rust

Answer 4

Cause - over reliance on fungicidal chemicals with similar mode of activity.
Solution - Cultural control techniques, plant resistant varieties, if using chemicals alternate chemicals, ensure chemicals have different modes of activity.

Question 5

Resistance in mice.

Answer 5

Cause - continual use of same rodenticide.

Solution - alter control methods to include cultural and biological.