Which class of pesticides is derived from natural sources, such as chrysanthemum flowers?

The correct answer is pyrethroids, which are a class of pesticides derived primarily from natural sources like chrysanthemum flowers. Pyrethroids are chemically modified versions of pyrethrins, the active compounds found in these flowers. They are widely used due to their effectiveness in controlling a variety of pests, including insects in agricultural and residential areas.

These compounds work by disrupting the normal function of the nervous system in insects, leading to paralysis and death. Their natural origins and effectiveness make them a popular choice in both organic and conventional pest control strategies.

In contrast, organophosphates are synthetic chemicals that inhibit a specific enzyme in the nervous system, fipronil is a newer synthetic insecticide that also affects the nervous system but is not derived from natural sources, and nematicides are specific types of pesticides used to control nematodes and do not originate from chrysanthemum flowers. Understanding the origins and mechanisms of different classes of pesticides is crucial for their effective and responsible use in pest management.