Neem gains honour as India's wonder tree

Known in ancient India as a tree with many wondrous properties, the neem tree is slowly drawing the attention of the country's scientific and entrepreneurial community.

 
By Anjani Khanna
Last Updated: Sunday 07 June 2015

Neem gains honour as India's wonder tree

-- (Credit: H K Barman)NOW THAT "neemania" has gripped scientists in the West and neem (Azadirachta indica) is being hailed as the wonder tree that can solve global problems from locust swarms to AIDS, Indian scientists are jumping onto the bandwagon. And, after Western scientists proved neem-based pesticides are safer than synthetic ones such as DDT and can be commercially produced, Indian bureaucrats are pressing manufacturers to get in on the act.

Western scientists have isolated several biologically active compounds called limonoids from the oil, seeds, bark and leaves of neem. Though their research was intended primarily to develop speedily degradable, safe and effective pesticides, they have expanded their efforts to discovering medical and agricultural applications of neem -- from male spermicides to nitrogen regulators.

In India, however, research on neem has been both sporadic and scattered. Though neem is native to India and pioneering work was being carried out here until the 1960s on the commercial use of neem oil and neem cake, the centre of neem research has since shifted abroad and is concentrated now in Germany, UK, USA and Japan. Research on neem oil and neem cake began in the 1920s at the Indian Institute of Science in Bangalore. And, in 1960, neem's insecticidal properties began to be studied at the Indian Agricultural Research Institute (IARI) in Delhi. Two years later, IARI scientist S Pradhan was credited with saving the entire stock of plants at IARI from marauding locusts by spraying them with neem kernel extract.

Despite all this, IARI chemist C Devakumar states categorically, "We are 10 years behind the West. There is a need to consolidate, integrate and channelise the application of research efforts. We need a technology mission that will deal with biological pesticides."

The search in the West for safe biological pesticides began with the realisation that synthetic pesticides leave harmful residues that can accumulate in animal tissue and to which several insects have growing resistance. Neem was an obvious choice for them because Indian farmers have used it for centuries to protect their crops and their stored grain. An indication of the seriousness of neem research in the West is that three international conferences on neem have been held to date -- in Germany in 1980 and 1983 and in Kenya in 1986. And, a signal of India's belated awakening to neem's commercial potential is that the fourth conference on neem is scheduled early next year in Bangalore.
Early findings In 1942, S Siddiqui of the Council for Scientific and Industrial Research isolated nimbin, a limonoid, from neem. And, one of the first scientists to transfer research findings from the laboratory to the field was B G Joshi of the Indian Central Tobacco Research Institute in Andhra Pradesh, who demonstrated to farmers in Rajahmundry in 1976 that an aqueous suspension of neem seed kernels effectively repels the tobacco caterpillar moth (Spodoptera litura), a major pest. Farmers in Rajahmundry now collect neem seeds themselves, prepare suspensions and spray their tobacco plants using either a sprayer or a straw broom. Another major breakthrough came in the late 1970s with the isolation of another limonoid, azadirachtin, by J H Butterworth and E D Morgan at the University of Keele, UK. Azadirachtin and other limonoids such as meliantrial and salannin are extremely effective against insects, even in minute quantities. Azadirachtin, for example, repels insects, inhibits their feeding practices and affects their hormonal balance by mimicking an insect hormone and thereby preventing larval insects from shedding their external skeletons and maturing. "You can stop an entire generation of insects with neem by ensuring they do not mature and reproduce," explained IARI entomologist R P Singh.

Neem reportedly controls more than 200 species of insects, mites and nematode worms and major pests such as locusts, rice and maize borers, pulse beetles and rice weevils. Singh, who has worked extensively on neem, explained, "Unlike single synthetic formulations, neem is a collection of biologically active ingredients and, as a result, insects find it difficult to develop resistance to neem." In laboratory experiments, for example, it was seen that even after 423 generations, the cabbage moth (Plutella xylostella) was sensitive to neem even though it developed resistance to many other synthetic pesticides.

Harmless to humans
An especially valuable quality of neem is that it is harmless to humans and other mammals. Surprisingly, neem extracts are also harmless to most insect predators. But there is some evidence that neem can affect a variety of marine life and a recent letter in Science noted that though neem oil was a promising biological control agent, it could be harmful to non-target organisms such as crustaceans because neem constituents inhibit the formation of chitin -- the stuff that forms the skeleton of crustaceans like crabs and lobsters. Judith Weis of USA's Rutgers University warned neem could enter aquatic systems and damage organisms important to the food chain.

Laboratory studies with fish show neem extracts have few ill-effects but in one trial, tadpoles and gambusia (mosquito-eating fish) died when neem extracts were added to the water. This was reported by M C Jotwani and K P Srivastava in their book on neem, published recently by the National Research Council of USA. An NRC study indicates only medium-sized heads were formed after cabbage was sprayed with neem extracts. On the whole, however, neem compounds are absorbed by many plant species and render them effectively invulnerable to several leaf chewing and sucking insects.

Given the unique qualities of neem compounds, once isolated, they can be quickly used as an ingredient in pesticides. In the early 1980s in the US, Robert Larson of Vikwood Botanicals, who had observed farmers in India use neem, developed a neem kernel formulation named Margosan-O, which contains 3,000 parts per million of azadirachtin.

Big bucks
Neem means big money in the West and business sources estimate it has the potential to capture a US$ 100 million share of the US$ 6 billion annual pesticide market. Neem-based insecticides are now allowed only on non-food crops, but the non-food crop market is expected to expand rapidly once the US Environment Protection Agency gives neem the green signal. US companies have been quick to catch on to neem's commercial potential and a number of neem-based pesticides such as Ringer's Bioneem and Agridyne Technologies' Azatin are ready for the market.

In Australia, after scientists discovered neem to be an effective agent against blow flies, which burrow under the skin of sheep and kill them, about 1,000 ha have been planted with neem trees in Queensland at a cost of more than US$ 4 million. And 11 companies are reported to have been established in Australia to produce and distribute neem products to sheep farmers.

Indian indifference
However, in India, the market preference is still for broad-spectrum, synthetic pesticides and farmers generally ignore the humble neem as being "too primitive". Agricultural scientist C M Ketkar of Pune, the most ardent promoter of neem in India, said the country's approximately 14 million neem trees annually produce about 0.5 tonnes of fruit, but only 20 per cent of this is collected to extract neem oil for soap-making and other pharmaceutical purposes.Now, however, emulating their counterparts in the West, scientists are working at IARI in Delhi, the Indian Institute of Chemical Technology in Hyderabad and the National Chemical Laboratory in Pune on developing and patenting neem-based pesticides that will be on store shelves soon. "Several private industries are interested in promoting this technology," says IARI's Devakumar. "But they need research and development back-up."

National Organic Chemicals Industries Ltd (NOCIL) is interested in promoting a formulation called Vepaol -- vepa means neem in Telugu and Malayalam -- developed at the Hyderabad institute and is expected to begin production before 1994. Unlike pure azadirachtin, which degrades quickly in the field, NOCIL's azadirachtin-based formulation will stay stable for two years. As part of its 1979 programme on developing pest control agents from plant materials, National Chemical Laboratory scientists started work on neem and soon established that neem extracts have a number of insect-repelling properties. They have isolated two extracts -- Neemrich I and Neemrich II -- that are active against a number of soft-bodied and sucking insects such as aphids, jassids, thrips, cotton white fly and sorghum shoot fly.

The Union Ministry of Agriculture has recently approved four neem-based pesticides made in India. Two of them -- Margocide CK 20% and Margocide CK 80%, with different concentrations of azadirachtin -- will be in the market soon (see box). The Tata Oil Mills Company (TOMCO) has reportedly got a neem-based pesticide registered with the US Environment Protection Agency and is exporting neem products to the US.

A simple technology using neem cake -- the kernel residue after oil extraction -- has been developed by scientists at the Indian Agricultural Research Institute to reduce nitrogen loss substantially. (See Down To Earth, June 15, 1992.) "Nitrifying" bacteria convert nitrogen compounds in urea and ammonia fertilisers to useless nitrogen gas that eventually finds its way into the atmosphere and to highly soluble nitrates that are leached out of the soil.

Compounds in neem cake called triterpenes retard the activity of the nitrifying bacteria, regulating nitrogen supply to plants. More nitrogen is recovered by plants when neem cake coated urea is applied, instead of untreated urea. Trials at the IARI showed when 160 kg of urea and 40 kg of neem cake are applied on one hectare of rice, the yield is 0.6 tonnes higher than when 200 kg of urea alone is applied.

Though this technology has been known for some time, it has not been picked up by fertiliser manufacturers. Fertiliser prices are fixed according to their nitrogen content. Though more effective, a urea-neem cake fertiliser will contain less nitrogen for the same weight -- and accordingly, the price will be lower, which is a disincentive to manufacturers. Godrej Soaps, however, is marketing a new product called Nimin, which contains neem-based triterpenes to be mixed with urea (see box).

Bottled pesticides
Though neem-based pesticides are making slow inroads into the Indian pesticide market, a note of despondency is being voiced by Ketkar, who has done so much to promote low-cost, neem-based technologies. "We don't need to make our farmers dependent on bottled pesticides," he pointed out. "Simple, low-cost technologies that they themselves can make are essential to exploit neem's potential fully." Ketkar explained farmers can easily extract neem seed oil and use it to protect stored grain against pests. "In the past, farmers used to mix neem paste with the mud used to make earthen grain stores," he said. Ketkar found that spraying a water solution containing neem powder on plants would protect them effectively against caterpillars, grasshoppers, locusts, aphids and whitefly. He conceded, however, that while homemade neem extracts cannot replace commercial pesticides entirely, "they can certainly reduce their use."

Medicinal properties
Taking their cue from ayurveda, scientists have been studying neem as a possible treatment for a number of ailments and in particular as a spermicide (see box).

Scientists have also rediscovered that neem has important fungicidal, antibacterial and even antiviral properties. Its anti-malarial and anti-diabetic properties have been confirmed by researchers and preliminary medical investigations reveal neem bark extracts can control cancerous tumours in mice.

Neem preparations also reportedly work well against a variety of skin diseases, septic sores and infected burns. Dabur has developed neem capsules that can reportedly cure acne (see box). Says M R Unniyal, assistant director of the Central Council for Research in Ayurveda and Siddha in New Delhi, "Neem oil, marketed as Triple 7 oil, is commonly prescribed for psoriasis and other skin diseases."

Many strains of the bacteria, Staphyloccus aureus, a common cause of food poisoning and secondary infections in diseases like meningitis, which are resistant to penicillin, can be suppressed by neem extracts. Neem extracts have also effectively controlled some strains of the much feared Salmonella typhosa that, transmitted via water and food, causes typhoid, food poisoning and other stomach disorders. Recent studies in the USA have shown neem leaf extracts inhibit certain enzymes in the hepatitis B virus, and German studies indicate neem extracts have been effective against the herpes virus.

And, neem's effectiveness against the AIDS virus will be studied by NII's Shakti Upadhyay, who left recently for Harvard University.

Thus, neem could become the hottest export of the developing world, says Brian Cummings of Agridyne Technologies. According to one report, refined neem with anti-cancer and anti-diabetic properties can sell for as much as US$ 500 per kg and recently, a Japanese pharmaceutical firm, Johoku Chemical Co Ltd, made plans to send a trade team to tie up with suppliers of neem-based products to meet the increasing demand for non-synthetic products in that country.

The beauty and strength of neem is that it can be used in formulations from the crudest to the most sophisticated. In tomorrow's world, both datoon -- the neem twig chewed each morning by hundreds of thousands of Indians to clean their teeth -- and complicated pesticide formulations for use abroad, will both have a place under the sun.

Subscribe to Weekly Newsletter :

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.