Neem Oil as Insecticide

Since time immemorial, neem has been associated with the traditional medicine of India, which is believed to be the native place of this tree. Neem tree is also considered to be sacred in some parts of the country, owing to its therapeutic and pest control properties. Nowadays, the oil extracted from the fruits of this tree is used in the manufacture of soaps, cosmetics and insecticides. This oil is also used to prepare ayurvedic and unani medicines, mainly used in the treatment of various skin diseases, fevers, rheumatic disorders and inflammations. It is also very popular as a means of pest control and is widely used as an insect repellent and insecticide.

Neem Oil and Insects
Neem oil, which is light to dark brown in color has a bitter taste and a pungent smell. This oil, in its original form, does not mix with water and so it is mingled with surfactants in order to make it soluble in water. Such a solution works as a bio-pesticide for organic farming. People who want immediate effects cannot find satisfaction with neem oil, as it works gradually. You cannot expect the insects to die, the moment you spray neem oil solution on them. Let us find out the function of neem oil as an insecticide.

Neem oil has many ingredients and the action of each and every ingredient is not known. Various insect species react differently to neem oil and it is also observed that this oil does not cause harm to beneficial insects. It is believed that neem oil affects only chewing and sucking insects. From what has been observed till date, scientists have evolved a theory of the action of neem oil as an insecticide. According to them, the ingredients of neem oil can block the action of hormones in insects. As neem oil enters the system of the insects, the hormones in their bodies stop working properly. As a result, the insects stop their activities, like, eating, mating and laying eggs. Even if eggs are laid, they don't hatch. This inaction affects the very survival of the insects, thus resulting in the dwindling of their population.

It is also observed that the smell of neem oil wards off insects and deters them from eating the crops. As far as pesticides are concerned, they tend to wash away with rain or degenerate with sunlight. Other strong ones, which can withstand these factors, may stay forever. Neem oil also disintegrates easily, but its advantage is that the plants absorb and retain it in their tissues. The insect is deterred due to the smell or may take one or two bites and leave the plant. The presence of trace amounts of neem oil cannot cause any harm to human beings, as it is therapeutically consumed in small amounts as part of the treatment of various diseases. It is also believed that like white oil and olive oil, neem oil too creates a coating over the insects, when sprayed on them. This coating suffocates them to death.

Using Neem Oil as Insecticide
In order to use neem oil as insecticide, it should be diluted with water. Four teaspoons of neem oil is sufficient for one gallon of water. This solution can be sprayed on the foliage or can be used as a soil drench (one liter for one square meter of soil). Surfactants are used to enhance the efficiency of neem oil as an insecticide. Usually, liquid dishwashing soap is added for this purpose, at the rate of one tablespoon per gallon. The best time for application of neem oil as an insecticide, is early morning, late afternoon or evening. This is to avoid harm to the beneficial insects, which are active in the daytime only. Or else, the spray may coat them with neem oil and lead to their death. Once the application becomes dry, it cannot harm them, as they do not feed on plants, like, other harmful insects.

If you are applying neem oil as a preventive measure, a 7 to 14 day schedule is recommended and if the use is to control the pests which have already attacked the plants, then a 7-day schedule is sufficient. It can control many pests, like, aphids, moth larvae, whitefly, Japanese beetles, scale and spider mites. Neem oil is known to kill mites and also act as a fungicide against black spot, leaf spot, anthracnose, rust, mildew, etc. You can replace your chemical pesticides with neem oil for your houseplants, or your crops or for the plants in your garden.