Pyrethrins plants producing

Natural products can occasionally be used for crop protection purposes in their own right. The natural pyrethrins, such as pyrethrin I (Figure 1), are insecticidal compounds produced in the flowers of the plant Chrysanthemum cinerariaefoUum, and are well-known examples. They are used to control insect pests on various crops and on farm and domestic animals, but their use outdoors is limited by their poor stability in sunlight. Incidentally, this example is highly appropriate for this conference held at the University of Nairobi, because much of the world s supply of pyrethrins is produced in Kenya. 

Similar in importance to hunting for biosynthetic genes is clarifying whether other plant species are able to produce biosynthetic intermediates themselves using high-sensitivity LC-MS. If so, how close are such compounds located to pyrethrins in the pathway It could be that pyrethrin production is too small to be noticed in other plant species. Even if this is not the case, it should be noted that some other plant species produce chrysanthemyl pyrophosphate (16) and r/.v-jasmone (25). 

Pyrethrins and pyrethroids are probably the best known and safest classes of natural or synthetic insecticides, widely used in domestic and agricultural applications (1-7). Pyrethrins are natural insecticides derived from the Chrysanthemum cineraria flowers the plant extract, called pyrethrum, is a mixture of six isomers (pyrethrin I and II, cinerin I and II, jasmolin I and II) which was first used in China in the century AD, during the Chou Dinasty. The world pyrethrum market is worth half a billion US dollars [main producers are East Africa highlands (Kenia, Tanzania and Rwanda) and Australia] however, its availability is subject to cyclical trends, due to rains and relations with farmers, who face high harvest costs also due to the fact that the flowers have to be... 

The toxicity of these materials has led to the development of alternative means of insect control. Pyrethrins are natural insecticides produced by plants to ward off predators. Over the past decade or so, more of these natural defenses called allelochemicals have been investigated in the hopes of using them commercially. See the ASIDE on pyrethrins. 

Several nerve toxins produced by plants are interesting because of their insecticidal properties. Insecticidal nicotine is extracted from tobacco. Rotenone (Figure 19.2) is synthesized by almost 70 legumes. This insecticidal compound is safe for most mammals, with the notable exception of swine. The most significant insecticidal plant derivatives, however, are the pyrethrins, discussed below. 

Synthetic pyrethroids are produced to duplicate or improve the biological activity of the active principles of the pyrethrum plant, a flowering plant of class crasan-themum species. Pyrethrum is a natural botanical chemical, the active principal of which is extracted from flowers of the pyrethrum plant and are known collectively as pyrethrins. ... 

All manner of pollutants are considered under the discipline of terrestrial ecotoxicology including pesticides, persistent organic pollutants, other organic substances, and metals and metalloids (e.g., selenium and arsenic). Naturally occurring toxins such as those produced by poisonous plants, snakes, or invertebrates generally are not included unless people intentionally apply them for pest control. For example, the pyrethroid pesticides are derived from the naturally occurring pyrethrin toxin that is found in chrysanthemum. 

The naturally occurring pyrethrums have been used as Insecticides since the 1800s. These compounds are extracted from the flowering portion of the Chrysanthemum plant. The flowers produced In Kenya have, on average, 1.3% pyrethrins. These pyrethrum extracts are a major agricultural product for that country. 

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