A few spoonfuls added to a bucket of soapy water and applied to the garden controls pests. Studies show that soil fertilising properties of neem block soil bacteria from converting nitrogenous substances into useless nitrogen gas. Plant roots are protected from nematodes and termites. British researchers isolated azadirachtin, an active insect antifeedants, from the neem seed. An insect antifeedant is a compound that prevents insect feeding without killing the insect directly, unlike traditional insecticides, which are non-selective.
Some plants absorb neem systemically and are thus protected.
Since beneficial insects prey on insects and not the plants, this explains why they are not harmed. Neem controls insect pests now resistant to standard pesticides, such as sweet potato whitefly, western floral thrips, diamondback moth and some leaf miners. Growing evidence concludes that neem intervenes at several insect stages. The neem compounds are similar in shape and structure of hormones necessary to only insects. Insects absorb these compounds that block their endocrine systems.