Question

Which of the following is not insecticide synergist ?

• A. Dillapiole
• B. Sesamol
• C. Nimbinol
• D. PBO

Hint:

The most common synergists (like PBO, sesamol, and dillapiole) contain a methylenedioxyphenyl group.
This group binds to and disables cytochrome P450 enzymes inside the insect, preventing it from breaking down the insecticide.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
An insecticide synergist is a chemical that is not toxic on its own, but enhances the effectiveness of an insecticide when mixed with it.
Synergists function by blocking the enzymes (like cytochrome P450 monooxygenases) that insects use to metabolize and detoxify the insecticide.

Step 3: Detailed Explanation:
Let us evaluate each compound:
1. Dillapiole:
This is an organic compound extracted from dill essential oil.
It is a well-known natural synergist that enhances the performance of pyrethrin and carbamate insecticides.
Thus, Option (A) is incorrect.
2. Sesamol:
This is a natural organic compound found in sesame oil.
Its methylenedioxyphenyl structure acts as a natural synergist by blocking insect metabolic enzymes.
Thus, Option (B) is incorrect.
3. Nimbinol:
Nimbinol is a triterpenoid compound extracted from neem (*Azadirachta indica*) seeds.
Unlike synergists, nimbinol is an active ingredient that has direct insecticidal, anti-feedant, and growth-disrupting properties against insects.
It is not classified as a synergist.
4. PBO (Piperonyl Butoxide):
PBO is the most widely used synthetic organic synergist in commercial pesticides.
It is formulated with pyrethrins to maximize their effectiveness.
Thus, Option (D) is incorrect.

Step 4: Final Answer:
Nimbinol is not an insecticide synergist.
Therefore, the correct option is (C).