Associate Certified Entomologist (ACE) Practice Exam

What is the mechanism of action for phenylpyrazoles?

1. Inhibit neuromuscular junctions

2. Block the production of enzymes

3. Inhibit energy production and disrupt the nervous system

4. Stimulate neurotransmitter release

The correct answer is: Inhibit energy production and disrupt the nervous system

Phenylpyrazoles function predominantly by inhibiting energy production and disrupting the nervous system of target insects. These chemicals work by blocking specific sites on the gamma-aminobutyric acid (GABA) receptor, which is crucial for correct neurotransmission. This blocking action leads to continuous stimulation of the nervous system, ultimately resulting in an inability of the insect to control its motor functions. This disruption is significant, as it causes paralysis and eventual death in the pest. While the other mechanisms mentioned might affect different classes of pesticides or chemicals, they do not accurately describe the specific mode of action attributed to phenylpyrazoles. Inhibiting neuromuscular junctions typically involves different classes of pesticides that target synaptic transmission directly. Similarly, blocking the production of enzymes or stimulating neurotransmitter release is characteristic of other modes of action not related to phenylpyrazoles. Thus, the correct choice highlights the unique properties of phenylpyrazoles in disrupting the nervous system and energy production, leading to effective pest control.