Associate Certified Entomologist (ACE) Practice Exam

What mechanism prevents the effective transmission of nerve signals in insects treated with neonicotinoids?

1. Inhibition of sodium channels

2. Binding to nicotinic acetylcholine receptors

3. Disruption of calcium influx

4. Activation of GABA receptors

The correct answer is: Binding to nicotinic acetylcholine receptors

The correct answer is based on the role of neonicotinoids as a class of insecticides that specifically target the nervous system of insects. Neonicotinoids function by binding to nicotinic acetylcholine receptors (nAChRs), which are integral to the transmission of nerve signals. When neonicotinoids bind to these receptors, they mimic the action of acetylcholine, which normally activates these receptors to facilitate nerve signal transmission. However, unlike acetylcholine, neonicotinoids are not effectively degraded, thus causing prolonged activation of the receptors. This persistent activation leads to an overstimulation of the insect's nervous system, eventually resulting in paralysis and death. The mechanism of action directly impacts the efficacy of nerve signal transmission, as it disrupts the normal process by which nerve signals are transmitted and regulated. Understanding this mechanism is crucial for comprehending how neonicotinoids affect insect physiology and behavior, establishing the foundation for integrated pest management strategies and considerations regarding the ecological impact of these pesticides.