Neem oil

Contraction in the number of EPA-allowed biocides has heightened efforts to develop naturally derived preservatives and microorganisms capable of countering microbial degradation. Neem oil A. dirachta indica seed extract) has been featured as an exceptional natural candidate for the preservation of cosmetic products. Naturally derived chemicals with antimicrobial properties have been used since antiquity as preservatives. However, displacement of successhil synthetic products by natural products in preservatives of any category remains to be witnessed. 

The seeds from the Indian neem tree, Azadirachta indica, are the source of two types of neem-derived botanical insecticides neem oil and medium polarity extracts. Neem seeds contain numerous azadirachtin (Fig. 9) analogs, but the major form is azadirachtin and the remaining minor analogs are likely to contribute little to the overall efficacy of the extracts. Typically, solvent partitions or other chemical processes are required to concentrate this active ingredient to the level of 10% to 50% seen in the technical grade material used to produce commercial products. 

The same research group evaluated neem oil in the field [54]. They sprayed a 5% solution of the oil on infested honey bee colonies, killing about 90% Varroa mites but obtaining only a slight but not statistically significant decrease in tracheal mite infestation levels. Unfortunately this treatment caused 50% queen loss and the treated colonies showed one-third as many adult bees and one-sixth as much brood as untreated... 

Ndumu et al. evaluated the effectiveness of Azadirachta indica seed oil against the larvae of this parasite [95]. They administered the oil as hydroalcoholic solutions ranging 4.2-100% and computed the mortality within 60 hours. Authors observed that the mortality of larvae was concentration and time dependent 100% mortality was observed with 100% pure neem oil after 48 h. The LD50 of different concentrations were 33.3% (56 h) and 66.7% (48 h). Author also observed little or no adverse effects on treated animals. Furthermore, they stated that the open wound caused by tick bites and therefore exposed to potential fungal and bacterial attacks, could be protected by the microbicidal properties of the neem oil. Previously, the effectiveness of neem oil was also observed by Williams and Mansingh against another tick species of the same genus, A. cajennense, another cattle tick [96]. 

Neem extracts, pure constituents (i.e. azadirachtin) and formulated products showed positive results against Tetranichus mites [279-283]. Less polar extracts were considerably more toxic than polar ones or cold-pressed neem oil or commercial neem oil, and reduced the fecundity of the mites on treated plants and the survival of nymphs hatched from treated eggs application of pentane extract or neem oil in sublethal concentrations, caused growth disrupting effects on the nymphal stages and ovicidal effects. Quantification of the insecticidal substance azadirachtin in the extracts revealed that this compound was not the most active principle against the mites [284]. 

Akhtar, M., Mahmood, I. Control of root-knot nematode Meloidogyne incognita in tomato plant by seedcoating with Achook and neem oil. Integ Pest Control 1995 37 86-87... 

The neem products currently sold for pest control contain a seed extract known as azadirachtin, and not neem oil, so they do not have any fungicidal activity. But it s possible that neem oil products tor controlling both pests and diseases may be available in the future. 

Songkittisuntom (1989) increased mortality in the rice leafhopper, Nepho-tetlix vire cens, by 42.5 by adding 0-1% PBO to 5% neem oil. 

Various oils present in natural extracts have been classified as fixed oils or high boiling oils and essential or volatile oils. Very popular fixed oils are neem oils (nonedible), coconut, ground nut, soya, Sunflower, mustard etc. oils (edible). Some of the popular essential oils are rose oil, eucalyptus, lemon grass, jasmine, etc. oils of fragrance grade and cumin, coriander, cardamom, clove etc. of flavor grades. 

Hellothls vlrescens larvae fed two neem oil llmonolds In an artificial diet. Assay period was 10 days In a dark Incubator at 25°C and 80Z RH... 

Neemrich 100, a formulation containing 30% neem oil, applied dermally to albino rats at daily dose levels of 200, 400, and 600 mg/kg for 3 weeks, caused no overt signs of toxicity or abnormal behavior. Treated rats exhibited higher food consumption, gained weight, and showed no abnormal blood levels (129),... 

Malaysian infants given large (up to 5 mL) oral doses of neem oil for minor ailments showed vomiting, drowsiness, metabolic acidosis, polymorpho-nuclear leucocytosis, and encephalopathy within hours of ingestion (131). 

Plant derived pesticides Azadirachtin A and B (obtained from Azadirachta indica), Bacillus thuringiensis, Denis (rotenone), Neem oil (obtained from Azadirachta indica), nicotine, pyrethrum, Spinosad (a mixture of spinosyn A and spinosyn D) derived from soil bacterium Saccharopolyspora spinosa. 

Neem oil (margosa oil). Yellow plant oil from the crushed seeds of the neem tree (Azadirachta indica) originally indigenous to India but now also cultivated in Africa, Australia, and Central and South America. The composition of the oil depends strongly on its origin. The most important components are various stereoisomers and derivatives of azadirachtin (50-4000 ppm). It also contains numerous limonoids as well as various disulfides, the latter being responsible for the garlic-like odor of the oil. 

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