Pesticides derived from neem are classified as nonsynthetic, botanical herbicides and are called azadirachtin, neem oil soap or neem oil. Crushing the seeds and mixing with them water or alcohol derives the pesticide components. The resulting residue after oil extraction is called neem cake and is widely used as an agricultural fertilizer.
Azadirachtin is the main insecticidal active ingredient in neem oil. Other active ingredients belong to the triterpenes or limonoids groups. These ingredients hinder natural growth of pests and disrupt feeding patterns. The isolated, known limonoids include salannin, nimbin and meliantrinol.
The natural oil in neem works on pests in different ways. These include disrupting the normal growth process of eggs, larvae and pupae; sexual communication between pests; hindering the egg laying function of the females; infertility in adult pests; a poison for the pests in all stages of growth; and retarding the growth of chitin for the pests' exoskeletons. Neem oil is widely recommended, as it is harmless to beneficial insects such as bees, butterflies and spiders, as well as animals and people.
Neem tree products sell as emulsifiable concentrates. Though rate of efficacy depends on the pest's susceptibility and environmental conditions, certain general guidelines help ensure success. Make repeat applications of neem based products, use it on immature pests during the early stages of infestation, make application during warm weather conditions and apply the pesticide to transplants before planting into the ground. This helps control pests in their initial development stages.