Associate Certified Entomologist (ACE) Practice Exam

What is the mode of action (MOA) for organochlorines?

1. Blocking nerve impulses

2. Affecting sodium and chloride channels in nerve cells

3. Disrupting insect growth hormones

4. Causing dehydration in insects

The correct answer is: Affecting sodium and chloride channels in nerve cells

Organochlorines primarily function by disrupting the normal activity of sodium and chloride channels in nerve cells, which leads to uncontrolled neural stimulation. When an organochlorine compound enters an insect's body, it binds to these channels, preventing them from closing properly. This persistent activation causes continuous nerve impulses, resulting in paralysis and ultimately the death of the insect. Understanding this mechanism is crucial for pest control strategies, as it highlights how different insecticides interact with the nervous system of pests. Organochlorines have been historically significant in pest management but are now less commonly used due to environmental concerns and the development of resistance in target insect populations.