Associate Certified Entomologist (ACE) Practice Exam

How do carbamates differ from organophosphates in their mechanism of action?

1. They are permanent inhibitors of AChE

2. They are considered irreversible inhibitors

3. They are reversible inhibitors with weaker bonds

4. They have no effect on acetylcholine production

The correct answer is: They are reversible inhibitors with weaker bonds

Carbamates and organophosphates are both classes of pesticides that target the enzyme acetylcholinesterase (AChE), but they do so in different ways. The correct choice, noting that carbamates are reversible inhibitors with weaker bonds compared to organophosphates, highlights a fundamental difference in their modes of action. Carbamates typically form a temporary bond with the AChE enzyme, allowing for a reversible interaction. This means that after a certain time, the bond can break and the enzyme can resume its normal function of breaking down acetylcholine, which is crucial for nerve signal termination. This reversible nature leads to a shorter duration of action in comparison to organophosphates, which often form stronger, covalent bonds with the enzyme, leading to longer-lasting inhibition. In contrast, organophosphates are known to be irreversible inhibitors because they permanently bind to AChE, rendering it inactive and disrupting the breakdown of acetylcholine. This results in prolonged stimulation of nerve cells and can lead to toxic effects. The other statements do not accurately describe the differences between these two pesticide classes. They account for the fundamental biochemical interactions that define their impact on pest management and highlight the significance of understanding different pesticide mechanisms for effective application and