The genus Nucleopolyhedroviruses are

Options

A. effective against disease - causing pathogens .
B. effective against rodents
C. broad spectrum insecticides .
D. effective against insects and other arthropods.

Answer

To solve the question regarding the genus Nucleopolyhedroviruses, we will analyze the options provided and determine the correct answer step by step.

### Step 1: Understand the Genus Nucleopolyhedroviruses
Nucleopolyhedroviruses (NPVs) are a group of viruses that primarily infect insects, particularly those in the order Lepidoptera (moths and butterflies). They are known for their ability to cause disease in these insects and are often used in biological pest control.

### Step 2: Analyze the Options
1. **Effective against disease-causing pathogens**: This option suggests that NPVs target pathogens. However, NPVs specifically target insects, not pathogens. Therefore, this option is incorrect.

2. **Effective against rodents**: This option implies that NPVs can control rodent populations. However, NPVs are not effective against rodents; they are designed to infect insects. Thus, this option is also incorrect.

3. **Broad-spectrum insecticides**: This option suggests that NPVs act as broad-spectrum insecticides. While NPVs are used in pest control, they are not classified as traditional insecticides. Instead, they are specific to certain insect hosts. Therefore, this option is incorrect.

4. **Effective against insects and other arthropods**: This option accurately describes the function of NPVs. They are indeed effective against various insects and can also affect some other arthropods. This is the correct answer.

### Conclusion
After analyzing all the options, the correct answer is:
**Option 4: Effective against insects and other arthropods.**