Pyrethrum (Chrysanthemum cinerariaefolium) is a small perennial plant commercially grown for extraction of natural compound (pyrethrins) which used to make insecticides. Pyrethrins are a mixture of six chemicals that are pyrethrin I, pyrethrim II, Jasmolin I, Jasmolin II, Cinerin I and Cinerin II. These are commonly used for indoor purposes and to control mosquitoes, fleas, flies, moths, ants, and many other pests. 

The commercial cultivation takes place at an altitude of 1700 to 3000 meters above sea level. This is done because pyrethrin concentration has been shown to increase as elevation increases from the sea level. 

Currently, in Tanzania the crop is produced mostly in Mbeya, Arusha, Manyara,  Njombe, Songwe and Iringa regions with a total national average production  of 2,500 annually. Some other producers in Africa include Kenya & Rwanda while Worldwide, Tanzania is the second largest producer after Australia (Tasmania ) that produces almost more than two times of what is being produced here  in Tanzania. 

Unique Properties of Pyrethrum

1. Quick Acting – Pyrethrum poisons insects upon contact, attacking the central nervous system and resulting in faster knockdown and kill.
2. Low Toxicity – Pyrethrum is one of the least toxic insecticides, boasting a long history of proven safety towards humans and animals.
3. Binding Agent - Pyrethrum will bind to its application site and cannot be washed away by water.
4. Repellent – When not present in fatal amounts, pyrethrum acts as a repellent to protect food establishments and crops from insect pests.
5. Flushing Agents – Pyrethrum agitates insects in there hiding places, flushing them out and forcing them to be exposed to the insecticides.
6. Multi-purpose – Pyrethrum consists of a group of compounds rather than a single compound, resulting in a wider scope of activity against pests than other insecticides. It can be used against almost any pest in the house or garden.
7. No insect Immunity – Insect resistance is not a problem because of the complexity of the molecule that pyrethrum is composed of.

Importance of Pyrethrum to ecology

• Fate in water: Pyrethrum compounds are broken down in water to form nontoxic products. This reduces the toxicity to the living organisms found in water and other mammals including human beings that use water, hence ensures safe food web.
• Soil persistence: Soil application studies of pyrethrum showed a half-life of only 1-2 hours as it degrades rapidly when exposed to sun light. Therefore, the soil inhabitants which can survive during this exposure time will be safe and capable of reproducing.
• Wild life: Pyrethrum is slightly or moderately toxic to bird species, such as mallards and bobwhite quail. Natural pyrethrins are highly fat soluble, but are easily metabolized and thus do not accumulate in the body.
• Effect on beneficial insects: Synthetic pyrethroids are broad spectrum insecticides and are notorious for killing and repelling beneficial insects. However, since pyrethrum residues on the plant and soil break down quickly, the killing effect on beneficial living organisms is reduced.
• Source of food. Honey bees collect nectars from pyrethrum flowers which is used as food for their offspring during their early stages of life as well as nutritive food for human beings. Also, mole rats use these plants as food and source of water as it remains succulent during dry season
• Beautification. Pyrethrum plants can be used as garden flowers at home hence improve living environment and soil structure
• Balance of ecosystem: Pyrethrum used as pesticide therefore it reduces the number of insect pest when applied hence balance the ecosystem. Also, it protects plant/crop while maintaining primary source of food in an ecosystem.