Prior to the invasion of organic synthetic insecticides such as DDT, Parathion and Endrin etc., several plant-based formulations have been in use as insecticides against various crop pests. By using the natural insecticides the environmental pollution an be totally eliminated. 

 Unlike synthetic that kill both pests and predators outright the natural insecticides are relatively inactive against the latter. The supply of natural insecticides could be made continuous at a cheaper rate by regular cultivation. Most of the natural insecticides are easily biodegradable. However, the natural insecticides may not match synthetic insecticides in efficiency, but control the pest pollution at the right moment may be beneficial to the farmers. But one advantage is, natural insecticides extracted from plants in their semi-purified form have slow releasing action and prophylactic—that is if sprayed when infestation is low it prevents multiplication of insect population. 

 Among the natural insecticides rotenone from Derris elliptica (cube root) nicotine from tobacco leaf and pyrethrins from pyrethrum flowers (chrysanthemum cinerarifolium) attained commercial importance. Pyrethrum is still used in mosquito coils. Cube root of Malaysian origin and pyrethrum of East Africa are not grown in India. Attempts made by Central Government agencies to cultivate them are not very successful. Tobacco is more values for cigarette manufacturing.

Contact :-  Srikanthgb@neem.biz

 Related to Derris Elliptica a goof number of plants belonging to Tephrosia, Millettia , Mundulea and Derris are available in India. Chemical studies revealed that they elaborate low or nil rotenone contents and as such their insecticidal activity is low. Thus the prospects of making a botanical indigenous insecticide commercially viable is bleak. 

 It is at this stage the interest in Neem, Azadirachta Indica as pest control agent generated. Centuries before organic commercial insecticides were available, neem derivatives seeds, bark and leaf – were used in India to protect agricultural crops, household and stored grain pests. 

 It is well known practice in rural India to treat stored grains with neem oil or leaves. The antifeedant property of neem seed kernel against desert locust was reported by IARI in 1962. Neem cake was applied to rice fields against insect pests during 1930’s. But real interest in Neem research to make it a commercial pesticides, generated ever since International Symposium on Neem held at Federal Republic of Germany in 1980, followed by two more International Symposia again in Federal Republic of germany in 1983 and in Kenya in 1986. A world neem conference was held at Bangalore in 1993. 

 Intensive chemical investigation on neem seeds reveal that Azadirachtin, a complex and highly oxygenated compound belonging to tetranertriterpinoid class is the most potent antifeedant and growth disruptant to many insects. Antifeedant chemicals do not kill insects straightaway but when sprayed on crops or stored grains, the insect rather prefer to die of starvation rather than to consume the treated food. These antifeedants exert some kind of gustatory repellency on insects. Control of pests by antifeedants is now considered as safe and accepted method. But azadirachtin content is low (.03%) in seeds as well as in leaves and other parts. Leaves, bark and roots and seeds of neem also elaborate as many as sixty tetranortiterpinoids related to azadiracthin, all in minute quantities, but all these “neem bitters” contribute to the pesticidal activity. Attempts are in progress to synthesize in laboratories, organic compounds as analogues of azadirachtin incorporating some of its salient structural features. It may take several decades for the emergence of synthetic analogue. Besides the story of synthetic pyrethrins is disheartening. 

 Although pyrethins are known as natural insecticide since centuries a host of synthetic pyrethroids – fenevelarate, cypermethrin, decamethrine etc. – were introduced only during the last decade. Insects now developed resistance to them and pest resurgence is common especially cotton and rice fields, since they kill predators also. Their cost is also exorbitant. Farmers of Prakasam district, Andhra Pradesh, committed suicide, unable to control cotton pests with synthetic pyrethroids. Obviously pests developed resistance with synthetics. Soon they are destined go to background. 

 Synthetic insecticides, even if based on natural product structures, may not give us selectivity and environmentally safe pesticide. Therefore the efforts of the chemists all over the world is directed to fractionate “azadirachtin and related bitter rich fractions” from seeds or cake. Such fractions are found to exhibit diverse behavioral and physiological effects on insects, such as repellents, antifeedants, growth disruptants, ovipositional deterrents, ecdysone biosynthesis inhibitors and of course at higher concentration as insecticidals. Insects grown on crops sprayed with neem seed oil or graded fractions isolated from it, show sluggish growth, lay fewer eggs and besides feed far less. All these properties are beneficial in the pest control. 

 An American company has commercialized Azadirachtin rich extractive as spray and dust for application in agricultural crops. 15 to .3% azadiracthin rich fractions are available as harmless pesticides. In U.S.A, Saudi Arabia and many other countries, cultivation of neem trees, where climate is conductive, is in full swing, since neem trees are alien to that country.

Contact :-  Srikanthgb@neem.biz

 In India we are well poised to exploit neem as pesticide for the simple fact we have abundant trees. It is estimated there are 14 million neem trees, each providing 3-50kgs of ripe seeds. 30 kgs. Of neem seeds provide 6 kgs of oil and 24 kgs of cake. Oil is mostly used in soap manufacturing and cake as fertilizers. Only 25% seeds being collected in an organized manner. 

 Related to neem, Melia azadirach (Persian lilac) is also found in India. It also exhibits pesticidal properties. In recent years  several agricultural scientists of ICAR and agricultural universities are testing various parts of neem on laboratory grown insects and fields. Successful results were reported on neem oil – expelled or solvent extracted--, aqueous neem seed kernel extract or suspension, and raw neem cake as soil mix or aqueous cake extract as antifeedant/pestcide on several crops and stored grains. Neem cake is also used to control nematodes, aphids and scores of other insects and as nitrification inhibitor. Neem preparations have also systemic action on plants wherein photodecomposition is arrested. The results, especially on rice and cotton and vegetable crops are encouraging. Commercial readymade neem formulation from active fractions of neem seeds – dust W.D.P. (Water Dispersible Powder) or EC formulation – with high azadirachtin content commercially available. 

 Apart from pesticidal properties neem is well known for its medicinal properties. In India it is age-old practice to use barks and twigs for cleaning the teeth. Many tooth pastes and soaps containing bark extractives or neem oil available in the market. Nibin, the major bitter principle of oil had significant anti-ulcer potential. Neem oil is well known as mosquito repellent, as larvicides and for skin diseases as an external applicant. Burning neem leaves repel mosquitoes in homes, during evening times, it is a common practice in rural India. Recently neem oil is shown to be successful anti-fertility agent in humans also. Neem fruit pulp may be used to generate methane gas o carbohydrate rich base for industrial fermentations. Neem oil known to antidiabetic also. 

Neem is known to increase the soil fertility and water holding capacity. It foils excellently in social forestry , check soil erosion, as wind break and seeds provide income to rural people. It provides shade in agricultural fields. Leaf is an excellent source for goats. Neem wood resist termite attack, can be used for agricultural implements. Neem cake when mixed with urea acts as nitrification inhibitor, to slow the decomposition of urea. Besides neem cake is good organic manure. 

 Neem as a harmless and safe pesticide fits into integrated pest management and organic forming. 

 Neem hailed as “Wonder Tree”, “Botanical Marvel”, “Gift of Nature” and “Village Pharmacy” is India’s contribution to the world as pesticide and medicine. 

 The other environmentally safe botanical pesticides like Annona Squamosa (seeds_, Pongamia Pinnata (seeds), Vitex negundo (leaf) are also plenty and quite promosing.