The neem tree (Azadirachta indica) is native to Southeast Asia and India where it is a fast growing ornamental shade tree. For thousands of years, Indian farmers have been aware of the insecticidal properties of the neem tree. Its branches were hung in granaries to protect stored grain from insect attack. Historically, neem has also been used in India for both cosmetic and medicinal purposes. For example, oil extracted from the seed is used in soap, wax and lubricants and its twigs have been traditionally used as a toothbrush. Since the 1970s, scientists in Europe and the United States became interested in neem because of its insecticidal properties plus its low toxicity to mammals.
Substances with pesticidal properties are found in all parts of the neem tree. However, the greatest concentrations of these substances are found in the seed. Azadirachtin, the active ingredient in many pesticides currently available, is extracted from the seed kernels. Azadirachtin consists of more than 25 different but closely related compounds. In another extraction process, neem oil is extracted from the seed kernel. -more-