Pyrethrum

Pyrethrum is a genus of several old world plants in the daisy family (Asteraceae). They are native to southwestern Asia, northeastern Europe, and northern Africa. The plants have been used for centuries as an insecticide and lice repellent. The active components in pyrethrum are contact poisons which quickly penetrate the nerve system of the insect. A few minutes after application, the insect cannot move or fly away. But, a "knockdown dose" does not mean a killing dose. Pyrethrum has been used for centuries as an insecticide, and as a lice remedy in the Middle East.

History

Pyrethrum has been used for centuries as an insecticide, and as a lice remedy in the Middle East. It was used as a lice remedy in the Middle East as early as 400 BC, and was widely used in the 19th century to control pests in stored grain.

Cultivation and Production

Pyrethrum is economically important as a natural source of insecticide. The flowers are pulverized and the active components, called pyrethrins, contained in the seed cases, are extracted and sold in the form of an oleoresin. This is applied as a suspension in water or oil, or as a powder. Pyrethrins attack the nervous systems of all insects, and inhibit female mosquitoes from biting. When not present in amounts fatal to insects, they still appear to have an insect repellent effect. They are harmful to fish, but are far less toxic to mammals and birds than many synthetic insecticides and are non-persistent, being biodegradable and also breaking down easily on exposure to light. They are considered to be amongst the safest insecticides for use around food.

Uses

Pyrethrum is used in the manufacture of insecticide and is considered to be amongst the safest insecticides for use around food. It is also used in the manufacture of other industrial products such as paper, textiles, and leather.

See Also

• Insecticide
• Asteraceae
• Biodegradable

References

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