Question

Match the mode of action of the given insecticides
List I
A. Pyriproxifen
B. Chlorantraniliprole
C. Indoxacarb
D. Propoxur
List II
I. Sodium channel blocker
II. Inhibitor of acetylcholinesterase
III. JH mimic
IV. Calcium channel activator
Choose the correct answer from the options given below:

• A. A-III, B-IV, C-I, D-II
• B. A-II, B-I, C-IV, D-III
• C. A-IV, B-II, C-III, D-I
• D. A-II, B-IV, C-I, D-III

Hint:

Match chemical classes to their target sites: - Pyriproxyfen $\rightarrow$ Juvenile Hormone (JH) Mimic - Diamides (Chlorantraniliprole) $\rightarrow$ Ryanodine Receptors (Calcium Release) - Carbamates (Propoxur) $\rightarrow$ Acetylcholinesterase (AChE) Inhibitor.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Insecticides are classified by the Insecticide Resistance Action Committee (IRAC) based on their specific biochemical site or mode of action in the target insect's physiological system.

Step 2: Detailed Explanation:
Let us match each insecticide to its biochemical mode of action:
- A. Pyriproxifen: This is an insect growth regulator (IGR) that acts as a juvenile hormone mimic (III. JH mimic), suppressing embryogenesis and metamorphosis in target pests.
- B. Chlorantraniliprole: This diamide insecticide binds to and activates ryanodine receptors in insect muscles, leading to an unregulated release of calcium ions from internal stores, matching with IV. Calcium channel activator.
- C. Indoxacarb: This oxadiazine compound acts by blocking voltage-gated sodium channels in the insect nervous system, causing paralysis, matching with I. Sodium channel blocker.
- D. Propoxur: This carbamate insecticide inhibits the crucial enzyme acetylcholinesterase at synaptic junctions, leading to a toxic accumulation of acetylcholine, matching with II. Inhibitor of acetylcholinesterase.
This gives the match: A-III, B-IV, C-I, D-II.

Step 3: Final Answer
The correct option is (A).