नीम के बायोपेस्टीसाइड: एकीकृत कीट प्रबंधन के लिए उपयुक्त जैव कीटनाशक

Continuous and excessive use of chemical pesticides over a period of time has resulted in serious problems such as development of insect resistance, insecticide-induced resurgence of insect-pests, toxicity to non-target organisms and also to human beings.

Now there is an urgent need to evolve an alternate coherent pest management programme, which is effective and environment friendly. It would be appropriate to identify chemicals, which render crop plants unattractive or unpalatable for feeding by insect-pests, and at the same time are fully biodegradable.

Several plant products possess the property of making crop foliage unattractive for feeding, and hence, form an important component of the current strategy of pest control called “Integrated Pest Management (IPM)”.

It involves planned execution of combination of different pest management practices, including cultural control, use of resistant varieties, biological control, use of synthetic chemicals, whenever necessary, use of pheromones, use of botanical products such as those derived from neem.

Making Neem water extract 

1. At first collection of ripe fruits placing a net below the neem tree.
2. Fruits are dissolved in water and pressure is given by hands. In this way seeds are separated.
3. Then seeds are collected from it and sun dried and if it is rainy season a machine is used for drying. These seeds are collected in gunny bags.
4. Then seeds are grinded by grinding machine or by indigenous technology.
5. Then 500 gm of neem dust is soaked in 10 litre of water for 12-16 hours.
6. Again pressing is done by hands for better extaction of Azadirechtin.
7. Then this solution is filtrate by a clean cotton cloth or a net. A white coloured milk like solution will be available.
8. With this milk like solution 10 ml of sticker is added and ready for application.

Some of the harmful pests controlled by Neem products

Neem has shown great promise in controlling several species of insect-pests of cultivated plants.

Neem control stem borer on young plants

1. A small amount of crushed neem seed powder should be mixed with the same amount    of dry clay or sawdust.
2. The mixture is placed in the funnel of young maize or sorghum plants.
3. Rain will gradually dissolve the active chemicals in the neem seed.
4. This treatment may need to be repeated every 8 to 10 days until the plants flower.

Nee cake control brown plant hopper

Neem cake has proved so successful in controlling brown plant hopper and other rice pests. It has been estimated that one neem tree provides enough ingredients to protect a hectare of rice. This use alone exemplifies the economic importance of future developing the neem tree for pest control.

Neem controls Army worm

Azadirachtin has proved an effective prophylactic against armyworms at extremely low concentration a mere 10 mg per hectare. 

Neem seed extract control Aphid

Water extracts of neem seed provide effective against Aphis gossypii on cucumber and okra and against Lipaphis erysimi on cabbage. This was in direct- contact sprays. Neem extracts applied in a systemic manner (that is, within plants) usually have little effect on aphids. Apparently, this is because aphids feed only on the phloem tissues, where, neem materials accumulate least.

Water based Neem spray to control Cutworm:-

Water based neem spray is most effective against pests such as cutworms. During the day the caterpillars stay on the ground and fed on plant roots. At night they eat young stems.

Plants most affected include many vegetables and other affected plants include maize, tobacco and coffee.

Neem to control fruit fly

Fruit flies are among the most serious horticultural pests. They cause million of dollars in damage in to fruits, and their very presence in the tropics is restricting dozens of delicious fruits from becoming major items of international trade. More important, the neem materials were compatible with the biological control organisms(braconid wasps) used to control fruit flies.

Neem cake to control soil borne pests:-

The neem cake, which is left after the oil is extracted from the seed, is also useful for controlling several pests, which live in the soil, particularly nematodes. Neem products effect various types of nematodes. This may be significant because certain of these thread worms are among the most devastating agricultural pests and are also among the most difficult to control. In addition, an increasing number of synthetic nematicides have had to be withdrawn from the market for toxicological reasons

Control of post harvest pests:-

Khapra beetle is a serious pest of stored wheat in northern India, whereas cigarette beetle causes extensive damage to almost all stored spices and dry tobacco. A specially prepared neem kernel dust formulation when mixed in smaller and higher concentrations with wheat seeds, arrested the growth and development of first instar and third instar larvae of the pest, respectively.

Control of Bruchid beetles in stored beans by Neem

• Neem oil is used to control Bruchid beetles, which are small beetles whose larvae eat into stored beans and other legumes.
• Mix a small quantity of neem seed oil with the beans or seeds before storing.
• The oil has a bitter taste, but is not reported to change the taste of stored beans for humans to eat.

Benefits of Neem biopesticide:-

Neem biopesticide (Emulsified concentrate) is well suited for an Integrated Pest Management (IPM) programme, because of the following salient features:-

1. Neem pesticide is a natural product, absolutely non toxic, 100 percent biodegradable and environmentally friendly.
2. It is suited for mixing with other synthetic pesticides and in fact enhances their action.
3. None or lesser quantity of synthetic pesticides need to be used, thereby reducing the environmental load.
4. Several synthetic pesticides being single chemical compounds cause easy development of resistant species of pests. Neem consists of several compounds  hence, development of resistance is impossible.
5. Neem does not destroy natural predators and parasites of pests thereby allowing these natural enemies to keep a check on the pest population.
6. Neem also has a systemic action and seedlings can absorb and accumulate the neem compounds to make the whole plant pest resistant.
7. Neem has a broad spectrum of action, active on more than 200 species of pests.
8. Neem is harmless to non-target and beneficial organisms like pollinators, honey bees, mammals and other vertebrates.

Conclusion

Neem has attracted worldwide attention in recent years due to its wide ranging properties. It is considered to be a promising tree to solve global problems in the coming years.

As a matter of fact neem tree grows wild throughout the country. But organized plantations of neem are necessary to realize its potential. The action of synthetic chemical pesticides on insects is immediate leading to their death. On the other hand, the action of neem compounds is indirect, and hence these compounds exhibit somewhat delayed response in insects as compared to that in case of chemical pesticides.

However, there is an added advantage with neem preparations that these are effective in one or the other way, at each stage of the metamorphosis in the life cycle of the insects i. e. egg, larval, pupal, or adults stage.

Thus, the neem based products offer excellent potential for the control of pests; furthermore, they are devoid of ill-effects associated with synthetic chemicals. The neem-based products could serve as models for future pesticides in IPM programmes.        

Author:   

Hiralal Jana

Assistant Professor

 Department of Agricultural Extension, College of Agriculture (BCKV)

P.O. Agricultural Farm; Kalna Road, Burdwan; West Bengal-713101

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