Question

Lufenuron is

• A. Electron transport inhibitor
• B. JH mimic
• C. Chitin synthase inhibitor
• D. Water balance disruptor

Hint:

Remember: Benzoylurea compounds (ending in "-uron" like Diflubenzuron, Lufenuron, Novaluron) are all Chitin Synthase Inhibitors (IRAC Group 15).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Insect Growth Regulators (IGRs) are modern, biorational insecticides that disrupt the normal development, molting, and metamorphosis of insects.
They target physiological pathways unique to arthropods, making them highly selective with low toxicity to mammals and beneficial vertebrates.

Step 2: Detailed Explanation:
Lufenuron is a benzoylurea insect growth regulator.
Its biochemical mode of action is classified under the Insecticide Resistance Action Committee (IRAC) as Group 15: Inhibitors of chitin biosynthesis.
Specifically, lufenuron interferes with the activity of the enzyme chitin synthase, preventing the polymerization of N-acetylglucosamine.
Without chitin synthesis, the insect cannot produce a new cuticle during molting.
As a result, when the immature insect attempts to molt, the old cuticle cannot be properly shed, or the new cuticle remains too soft, causing molting failure and death.
Let us review the other choices:
1. Electron transport inhibitor: E.g., Rotenone, Hydramethylnon, or certain mitochondrial complex inhibitors.
2. JH mimic (Juvenile Hormone mimic): E.g., Pyriproxyfen, Fenoxycarb.

Step 3: Final Answer:
Therefore, Lufenuron is a Chitin synthase inhibitor.