What is the meaning of 'selective toxicity' in aquatic pesticides?

• A. The pesticide is harmless to all organisms.
• B. A pesticide's ability to kill the target pest with minimal harm to non-target organisms.
• C. The pesticide degrades immediately in water.
• D. The pesticide works only in anaerobic conditions.

Answer: (B)

Selective toxicity means a pesticide is able to kill or control the target pest while causing minimal harm to other organisms in the aquatic environment. It relies on differences between the pest and non-target species—such as how the chemical is taken up, processed, or how its molecular target is present or differs in non-targets. In practice, a well-designed aquatic pesticide aims to disrupt a pest-specific mechanism or physiology at a dose that non-target organisms tolerate better. This helps protect fish, amphibians, invertebrates, and aquatic plants as much as possible, though no chemical is perfectly selective, so proper use is essential.