Associate Certified Entomologist (ACE) Practice Exam

What is the mode of action for spinosyns?

1. Blocks GABA-gated calcium channels

2. Binds to nicotinic acetylcholine receptors and blocks GABA channels

3. Inhibits protein synthesis in insects

4. Modulates hormone actions in insect development

The correct answer is: Binds to nicotinic acetylcholine receptors and blocks GABA channels

The mode of action for spinosyns primarily involves binding to nicotinic acetylcholine receptors in insects, which enhances synaptic transmission and leads to paralysis and death. This mechanism is somewhat unique because it effectively interrupts normal neural activity by preventing the insect's nervous system from responding appropriately to neurotransmitters. Spinosyns also exhibit a secondary effect on GABA (gamma-aminobutyric acid) channels, which further contributes to their insecticidal action. By blocking GABA channels, spinosyns disrupt the inhibitory signals that usually help to regulate neuronal excitability. This dual effect on both nicotinic acetylcholine receptors and GABA channels makes spinosyns effective in pest management, as it targets essential pathways in the insect nervous system, thereby ensuring a strong and rapid impact. In comparison, other modes of action mentioned in the incorrect answers do not accurately describe how spinosyns function. For instance, blocking GABA-gated calcium channels or inhibiting protein synthesis involves different pathways and does not relate to the specific activity of spinosyns. Modulating hormone actions is likewise relevant to specific growth regulators but does not characterize the primary action of spinosyns in disrupting neural function. Thus, the