METHODS TO PRODUCE BIOPESTICIDES/INSECTIDES USING NEEM

Neem fruits

In developing countries, the losses of crops due to pest, plant disease and competition from weeds is great. In households, pest and insects such as mosquitoes, cockroaches, mice etc pose risks such as the destruction of furniture, clothing and to the causation of various diseases, most seriously; malaria. Pesticides/insectides produced to kill these pests in order to prevent these damages, also tend to have adverse effects on humans in various ways, most especially those produced from synthetic materials. These adverse effects of headache, dizziness, catarrh worth investigating. The insecticides range from agricultural to household pesticides. Every category has its own effect, both on the targeted pest/insect and the environment in which it lives.Neem has attracted worldwide attention in recent decades mainly due to
its bioactive ingredients that find increasing use in modern crop and grain protection. The neem extracts have an effect on nearly 200 species of insects. It is significant that some of these pests are resistant to pesticides, or are inherently difficult to control with conventional pesticides (floral thrips, diamondback moth and several leaf miners). Most neem products belong to the category of medium- to broad-spectrum pesticides, i.e., they are effective over a wide range of pests.The practice describes a range of neem products such as the neem leaf extract, the neem seed kernel extract, the neem cake extract, the neem oil emulsion and also neem in combination with other plant extracts for the control of a variety of pests. The technologies using neem are extremely simple and these products can be made by the farmer in his own backyard. They have been tested in the farmers’ fields and satisfactorily proven to be effective in controlling a wide range of pests. They have also been used in controlling stored grain pests.

MATERIALS AND METHODS:-

THE EXTRACT OF NEEM KERNEL

50 grams of neem kernel are required for use in 1 litre of water. The neem kernel is pounded gently in such a way that no oil comes out. The outer coat is removed before pounding. This is used as manure. If pounded with the seed coat on, one and a half times the amount of seeds (75 g) is required. The seeds that are used for the preparation of neem kernel extract should be between three and eight months old. Otherwise, the quantity of azadirachtin in the seeds is quite low and hence they cannot be efficiently used for pest control. The pounded neem kernel powder is gathered in a muslin pouch and soaked overnight in water. The pouch is squeezed and the extract is filtered. To the filtrate, an emulsifier like khadi soap solution (a soap with no detergent) is added. One millilitre of emulsifier is added to I litre of water. The emulsifier helps the extract to stick well to the leaf surface.

Remarks: The kernel extract should be milky white in colour and not brownish. The kernel extract does not control sucking insects like aphids, white flies and stem borers. In these cases, one could use the neem oil spray solution.

THE EXTRACT OF NEEM LEAF

Neem leaf extract

For 5 litres of water, 1 kg of green neem leaf is required. Since the quantity of leaves required for the preparation of this extract is quite high (nearly 80 kg are required for 1 hectare), this can be used for nursery and kitchen gardens. The leaves are soaked overnight in water. The next day, they are ground and the extract is filtered. The extract is suited for use against leafeating caterpillars, grubs, locusts and grasshoppers. To the extract, emulsifier is also added.

Remarks: The advantage of using neem leaf extract is that it is available throughout the year.There is no need to boil the extract since boiling reduces the azadirachtin content. Hence the cold extract is more effective. Some farmers prefer to soak the leaves for about one week, but this creates a foul smell.

THE EXTRACT OF NEEM CAKE

100 grams of neem cake are required for 1 litre of water. The neem cake is put in a muslin pouch and soaked in water overnight. It is then filtered and an emulsifier is added at the rate of 1 millilitre for 1 litre of water, after which it is ready for spraying.

NEM OIL SPARY

Neem oil process

Thirty millilitres of neem oil are added to the emulsifier and stirred well to ensure that the oil and water can mix well. After this, 1 litre of water is added and stirred well. It is very essential to add the emulsifier with the oil before adding water. It should be used immediately, otherwise oil droplets will start floating. A knapsack sprayer is better for neem oil spraying than a hand sprayer.

THE EXTRACT OF PONGAM, ALOE AND NEM

1 kilogram of pounded pongam cake, 1 kg of pounded neem cake and 250 g of pounded poison nut tree seeds are put in a muslin pouch and soaked overnight in water. In the morning, the pouch is squeezed and the extract is taken out. This is mixed with 1/2 litre of aloe Vera leaf juice. To this, 15 litres of water are added. This is again mixed with 2-3 litres of cow’s urine. Before spraying, 1 litre of this mixture is diluted with 10 litres of water. For an acre, 60-100 litres of spray are used. This is effective in the control of pests of cotton and crossandra.

THE EXTRACT OF CUSTARD APPLE, NEEM, CHILLI

500 millilitres of water are added to 2 kg of ground custard apple leaves and stirred. This is filtered to get the extract and the filtrate is kept aside. Separately, 500 g of dry fruits of chilli are soaked in water overnight. The next day, this is ground and the solution filtered to get the extract. One kilogram of crushed neem fruits is soaked in 2 litres of water overnight and the extract is filtered. All the three filtrates are subsequently mixed with 50-60 litres of water, filtered again and sprayed over the crops.

Note: For all the above extracts, 250 millilitres of khadi soap solution should be added as an emulsifier before spraying.

GENERAL REMARKS ABOUT SPRAYING

1.  Spraying should be undertaken in the morning or late in the evening. Under hot conditions, the  frequency of spraying should be increased. In winter, spraying once in 10 days and every day in the rainy season is recommended.
2. Insects lay eggs on the underside of the leaves. Hence it is important to spray under the leaves also. 
3. While using a power sprayer, the quantity of water used should be halved.
4. It is better to use low concentrations of extracts frequently. 
5. As a general guideline, it can be said that each acre of land to be protected can be sprayed with 60 litres of ready-to-use solution (not the concentrate). Of course, the volume may have to be varied depending on the exact conditions prevailing, such as the intensity of the pest attack.

BIOLOGICAL EFFECTS OF NEEM ON INSECTS:-

The action of neem products as pest control agents can be manifested at different levels and in different ways. This is a very important point to be noted since the farmer would be used to the “knock-out’’ effect of chemical pesticides. Neem extracts do not exhibit this type of effect on pests but affect them in several other ways.

INSECT GROWTH REGULATION

Neem leaf dust

Regulation of the insects’ growth is a very interesting property of neem products which is unique in nature, since the products work on juvenile hormones. The insect larva feeds and as it grows, it sheds its old skin. This particular shedding of old skin is the phenomenon of ecdysis or moulting and is governed by an enzyme, ecdysone. When the neem components, especially azadirachtin, enter the body of the larva, the activity of ecdysone is suppressed and the larva fails to moult, remains in the larval stage and ultimately dies. If the concentration of azadirachtin is not high enough, the larva will die only after it has entered the pupal stage. If the concentration is lower still, the adult emerging from the pupa will be 100% malformed, and absolutely sterile.

FEEDING DETERRENT

The most important property of neem is feeding deterrence. When an insect larva sits on a leaf, it will want to feed on it. This particular trigger of feeding is given through the maxillary glands. Peristalsis in the alimentary canal is thus speeded up, and the larva feels hungry and starts feeding on the surface of the leaf. If the leaf is treated with a neem product, because of the presence of azadirachtin, salanin and melandriol, there will be an anti-peristaltic wave in the alimentary canal which produces something similar to a vomiting sensation in the insect. Because of this sensation, the insect does not feed on the neem-treated surface. Its ability to swallow is also blocked.

OVIPOSITION DETERRENT

Another way in which neem controls pests is by preventing the females from depositing eggs. This property is known as oviposition deterrence, and comes in very handy when the seeds in storage are coated with neem kernel powder and neem oil. The seeds or grains obtained from the market may already be infested with some insects. Even these grains could be treated with neem seed kernel extract or neem oil. After this treatment, the insects will not feed on them. Further damage to the grains will be halted and the female will be unable to lay its eggs during the egg-laying period of its life cycle. There are also other known modes of action:

1. the formation of chitin or the hard part covering the insect
2. mating as well as sexual communication are disrupted;
3. larvae and adults of insects are repelled;
4. adults are sterilised; and
5. larvae and adults are poisoned.

The use of neem products does not give immediate results, unlike chemical insecticides. Some patience is required after the application of neem products. Besides its insecticidal and nematicidal properties, neem is also a promising agent for control of plant diseases. It has also been demonstrated to possess anti-fungal properties. One of the problems with the use of chemical pesticides has been their impact on “non-target” species. Often they have proven harmful to various other species in the ecosystem that could be beneficial. However, neem extracts are devoid of these effects. Neem leaves and seed kernels, when incorporated into potting soil containing earthworms, increased the earthworm population by 25%. Neem products have proven to be remarkably benign to spiders and also other insects such as bees that pollinate

crops and trees, ladybug beetles that consume aphids, and wasps which act as parasites on various crop pests. Neem products have to be ingested to be effective. Those insects which feed on plant tissues, therefore, easily succumb. However, natural predators like spiders feed only on other insects while bees feed on nectar. Hence they rarely come in contact with significant concentrations of neem products.