Under which condition does degradation of a pesticide tend to slow down?

• A. Warm and humid
• B. Cool and dry
• C. Hot and dry
• D. Cool and humid

Answer: (B)

Degradation rates of pesticides in the environment are driven largely by temperature and moisture. Cooler temperatures slow the kinetic energy of molecules, so chemical breakdown happens more slowly. Dry conditions also limit hydrolysis and reduce microbial activity, since microbes need moisture to function. Put together, cool and dry environments minimize both abiotic chemical reactions and biotic degradation, letting the pesticide persist longer. Warm or humid conditions boost microbial activity and hydrolysis, speeding up degradation, so they don’t slow it down as effectively.