How is pyrethrum obtained from Asteraceae plants and used as an insecticide?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Sunflower — Asteraceae The flowering head of a sunflower (*Helianthus annuus*) is formed of yellow, petal-like ray flowers and a brown center of minute disk flowers.

Pyrethrum is obtained from certain species within the Asteraceae family, most notably Tanacetum coccineum and Chrysanthemum cinerariifolium (also known as the Dalmatian pellitory). The active insecticidal ingredients, known as pyrethrins, are harvested by drying and powdering the aromatic flower heads of these plants.1

As an insecticide, pyrethrum functions as a contact poison that affects insects and cold-blooded vertebrates. Because these natural compounds are generally nontoxic to birds, mammals, and plants, they are widely utilized in household sprays, livestock treatments, and as a method of pest control in organic farming.1

While these substances are effective, it is important to note that both natural pyrethrins and their synthetic counterparts, known as pyrethroids, can accumulate in water and wetland sediments, where they are toxic to fish and aquatic invertebrates.1