Insecticides usually act upon

Options

A. Muscular system
B. Digestive system
C. Nervous system
D. Circulatory system .

Answer

**Step-by-Step Solution:**

1. **Understanding Insecticides**: Insecticides are chemicals used to kill or manage insect populations. They work by targeting specific systems within the insects.

2. **Identifying the Options**: The question provides four options: muscular system, digestive system, nervous system, and circulatory system. We need to determine which system insecticides primarily affect.

3. **Analyzing the Nervous System**: Insects have a highly specialized nervous system composed of interconnected cells. This system is responsible for transmitting impulses and coordinating various bodily functions.

4. **Mode of Action of Insecticides**: Insecticides can be classified based on their target sites and modes of action. Many insecticides are neurotoxins, meaning they specifically target the nervous system of insects.

5. **Effects of Neurotoxins**: Neurotoxins disrupt neurotransmission by targeting enzymes involved in the transmission of nerve impulses. This disruption can lead to severe consequences, including paralysis and death of the insect.

6. **Eliminating Other Options**:
- The muscular system is not primarily targeted by insecticides.
- The digestive system is also not the main target; while some insecticides may affect feeding, they do not primarily act here.
- The circulatory system is not affected by insecticides in a significant manner.

7. **Conclusion**: Based on the analysis, the correct answer is that insecticides usually act upon the **nervous system**.

**Final Answer**: Nervous system

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