Neem - pesticides

Dried neem leaves and seed oil have been traditionally used to protect stored foods and fabrics from insect damage. Its use as a pesticide has triggered scientific research. A special chemical has been identified in neem that prevents insects from feeding and reproducing properly. This has now been made into a commercial product, but some controversial legal issues are being raised along the way.

Traditional uses

In rural areas of Bangladesh and India neem has a long been used to protect food from being spoilt by insects. Meat and fish would be cleaned using a water extract of neem and would then be stored with dried neem leaves. The walls and floor of the storage area would be painted with a mixture of cow dung, clay and neem oil. This mixture would deter insects from landing on the walls. It also interferes with the development of insects that ate food treated with the mixture.

Modern uses

The use of neem as a pesticide to kill or repel insects was first investigated in detail in the 1920s. Later, in the 1960s, chemists in Britain isolated one of the active compounds in neem seeds. This compound is called azadirachtin. It stops insects from feeding and also prevents them from growing properly and laying eggs.
Watercolour and line engraving of the branch of a neem tree. Detail of flowers and fruit.
Image: A compound found in neem seeds can be used in pesticides.

Products containing extracts from the seeds have been developed for sale as commercial insecticides and are available in some parts of the world but are not yet officially sold in Britain. Neem-based insecticides have been shown to be effective against over 200 different types of insects including head lice, fleas, locusts and mosquitoes.