Chrysanthemum cinerariifolium – Pyrethrum
C. cinerariifolium is called the Dalmatian chrysanthemum, denoting its origin in that region of the Balkans (Dalmatia). It looks more like the common daisy than other pyrethrums. Its flowers, typically white with a yellow center, grow from numerous fairly rigid stems. Plants have blue-green leaves and grow to between 45 to 60 cm in height. The plant is economically important as a natural source of insecticide. The flowers are pulverized and the active components, called pyrethrins, contained in thecases, 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 not persistent, being biodegradable and also breaking downeasily on exposure to light. They are considered to be amongst the safest insecticides for use around food. Kenya produced 90% (over 6,000 tonnes) of the world's pyrethrum in 1998, called py for short. Production in Tanzania and Ecuador is also significant.
SpraysPyrethrum was used for centuries as an insecticide, and as a lice remedy in the Middle East (Persian powder, also known as "Persian pellitory"). It was sold worldwide under the brand Zacherlin by Austrian industrialist J. Zacherl.
The flowers should be dried and then crushed and mixed with water. It should be noted that though the pesticide is organic, it can still be harmful to humans.
Pyrethroids are synthetic insecticides based on natural pyrethrum ( pyrethrins ); one common example is permethrin. A common formulation of pyrethrin is in preparations containing the synthetic chemical piperonyl butoxide: this has the effect of enhancing the toxicity to insects and speeding the effects when compared with pyrethrins used alone. These formulations are known as synergized pyrethrins.
Because of the natural insecticidal properties of the pyrethrums, they are used as companion plants, to repel pest insects from nearby crops and ornamental plants. They are thought to repel aphids, bed bugs (cimex lectularius), leafhoppers, spider mites, harlequin bugs, ticks, pickleworms and imported cabbage worms, among others that are in gardens and farms. For example, they are planted among broccoli plants for protection from several common insect pests.