The pyrethroids are composed of natural pyrethrins, which are isolated from chrysanthemum flowers, as well as newer synthetic materials. Older pyrethroids (e.g., pyrethrins and tetramethrin) degrade too rapidly in the environment to be used in agriculture. They are used in buildings, and because of their general safety, they are even applied to humans to control lice. Newer pyrethroids have greater chemical stability (e.g., permethrin and deltamethrin), which allows their use on many types of field crops. Another important use of permethrin is application to mosquito netting. Intoxication by pyrethroids develops rapidly (in 1 to 2 minutes), and involves a rapid loss of normal posture and movement called “knockdown.” Pyrethroids affect…



Source by Dr.Badruddin Khan