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                                                                                    New 2001   

                                                                                    E. H. Erickson and A. H.  Atmowidjojo

NEEM (also Margosa)

Azadirachta indica L. (syn. Antelaea azadirachta, Melia azadirachta, Melia indica), family Meliaceae

 

 

Neem (Azadirachta indica L.) is a member of the Mahogany family (Meliaceae) which includes a large array of tropical trees and shrubs native to both the Old and New World.  It occurs naturally in tropical and subtropical areas of Asia, Africa, Australia and South America.  Although largely uncultivated, Neem is the source of a wide variety of products including adhesives, beauty aids, fertilizers, herbs, lumber, pesticides, and numerous pharmaceuticals.  These products are variously derived from the bark, leaves and seeds (Conrick 1994; Puri, 1999;  Schmutterer, 1990).  In the dry season, the leaves are used as cattle feed (Vonderman, 1896).  Cultivation of neem for fire wood, proposed since the 19th century, has been limited.  Cultivation for oil extracts is largely unexplored.  Extracts of Neem, often called “Nature’s drugstore”, have been used in medicine for over 2,500 years (Conrick 1994) and perhaps much longer ( Puri, 1999).  Neem oil components, especially azadirachtin, have potential for use as pesticides because they inhibit molting, feeding and reproduction in phytophagous insects (Koul et al., 1987; 1990; Isman et al., 1990; Schmutterer, 1990; Tanzubil and McCaffery, 1990).  Neem produces a small fruit, about 3/4 in long, having a yellowish sweet pulp surrounding a small brown seed.  The pulp is believed to be edible (Conrick 1994).

 

Plant:

 

The spreading deciduous Neem tree grows to a height of 40 to 80 ft (12 to 25 m) (Bailey & Bailey, 1978; Conrick 1994; Schmutterer, 1990).  Its use as a slow growing evergreen shade tree in landscaping and as a house plant is increasingly popular.  The leaves are dark green and slender with resin secreting glands on young leaves near the shoot apex.  The bark on young branches is green, but grey to grey black on the main trunks.  Extra floral nectaries are present at the base of leaf petioles and on the adaxial side of leaflets (Dayanandan, 1994; Puri, 1999).  Neem thrives in the tropics with an extended dry season, is drought tolerant, and loses its leaves following moisture or cold stress (Puri, 1999;  Subramaniam, 1979).  It requires well drained soils, but tolerates poor soils and extreme heat.  The trees may live up to 200 years.     

 

Inflorescence:

 

Blossoms begin to develop on trees that are 3 - 5 years old and the tree is reproductively mature after ten years (Puri, 1999).  The flowers are pentamerous, regular, small, whitish pink and borne on axillary cymose panicles.  Flower buds open in the  afternoon and evening producing a strong scent at night.  The 0.2 in (5 mm) long protandrous flowers have a sweet jasmine-like fragrance and produce ample quantities of nectar.  The capitate tri-lobed sticky stigma stands above 3 - 5  bi-ovulate carpels, and at the same level of the ten anthers which are united into a single tube.  Each flower matures only a single seed.  Like other Meliaceae, Neem flowers from January through April with fruit ripening in June through August.  A Second minor flowering period may occur from July to October (Loke, et al.,1992; Puri, 1999; Raju, 1998).

 

The fruit is a ovoid drupe with a thin mucilaginous sweet pulp.  The green fruit darkens and becomes wrinkled at maturity.  The number of fruit/seeds per tree is highly variable.  Embryo abortion is common ( Puri, 1999).

 

Pollination Requirements:

 

Bisexual and male flowers occur on the same tree.  Floral anatomy and the absence of self incompatibility facilitates self pollination via the wind (Puri, 1999).  However, bees are required to effect cross pollination which ensures optimal seed/fruit set (Raju, 1998) and may limit embryo abortion.  Neem flowers are fragrant and highly attractive to bees.  They are a good nectar source and a minor source of pollen for bees (Bailey & Bailey, 1978; Crane et al., 1984; Chaubal and Kotmire, 1980; Kapil, 1957; Tewari, 1992).  The size of the pollen grain of A. indica (ca 55-65 microns in diameter) is within the size range for bee pollination (Nair, 1965).  The role of the extra floral nectaries, if any, in the pollination ecology of Neem appears unknown.

                                                                                               

Pollinators:

 

Bees observed visiting the anemophilous Neem flowers and effecting self- and cross pollination include Apis florea, A. cerana, Trigona spp. and Ceratina spp. (Raju, 1998).  Existing knowledge suggests that Meliaceous flowers are largely insect pollinated (Willemstein, 1987).  Although moths normally pollinate several species (Bawa, et al., 1985), members of this family of plants are important sources of pollen and nectar for honey bees.  Bees are listed as the major visitors of the flowers of related species, Swietenia macrophylla and Cedrela odorata, (Janzen, 1967; Crane et al., 1984; Roubik, 1989). 

 

Pollination Recommendations and Practices:

 

The cultivation of Neem on a large scale for its numerous products has been recommended, especially in dry areas.  For this, basic knowledge of the pollination strategies of Neem will be required.  Pollinator species should be conserved and encouraged to maximize seed set.    Clearly, profitable cultivation of Neem requires more study of its pollination ecology.

 

In India, neem trees are a major source of honey bee forage (Kohli, 1958; Nair, 1965; Ramachandran, 1937).   Planting of Neem is recommended to increase honey production (Crane, et al., 1984).  Neem honey is composed primarily of water, fructose and glucose (22.88%), sucrose (7.46%), ash (0.06%), free acid (20.8 meg/kg) (Crane, et al., 1984; FAO/WHO, 1989; Singh, 1962).  The honey is light amber in color (Kohli, 1958), and its viscosity is low.  The taste is good although slightly bitter.  Azadirachtin was not detected in Neem flowers or green fruit up to 40 days after anthesis (Rengasamy and Parmar, 1994).  Kohli suggests that because Neem is believed to be a great blood purifier and good for the eyes, Neem honey is highly valued.

 

Chemical analyses for Neem pollen are unavailable.  However, Neem pollen offers intriguing possibilities since all other components of the Neem tree have been shown to possess useful properties.  Pollen gathered by honey bees from many other plant sources is collected and sold by beekeepers, in various regions of the world, because of its nutritional and pharmaceutical value.  Studies should be conducted to determine whether Neem pollen is unique in this regard.

 

 

LITERATURE CITED:

 

Bailey, L. H., and Bailey, E.  Z. (eds.)

1978.  Hortus Third. 1290 p.  Macmillan Publ.  Co., Inc., New York, NY.

Bawa, K. S., Bullock, S. H., Perry,  D. R., Coville, R. E., and Grayum, M. H,  

1985.  Reproductive Biology of Tropical Lowland Rain Forest Trees.  II.  Pollination Systems.  Amer.  J. Bot. 72(3):346-356.

Chaubal, P. D., and Kotmire, S. Y.  

1980.  Floral Calendar of Bee Forage Plants at Sagarmal (India).  Indian Bee J. 42(3): 65­68.

Conrick, J.

1994.  Neem - the Ultimate Herb.  64 pp.  Neem Enterprises, Inc. Alachua, Fl.

Crane, E., Walker , P., and Day, R. 

1984.  Directory of Important World Honey Sources.  384 pp.  Intil.  Bee Res. Assn.

Dayanandan, P., Stephen, A and Murugandam, B.

1994.  Identification of cells that store triterpenoids of neem (Azadirachta indica). Abst. Amer. Jour. Bot. 81(6):21

FAO/WHO.

 

1989.  Codex Standards for Sugars (Honey).  Codex Alimentarius Commission, Suppl.

 

2 to Codex Alimentarius, Volume III, Joint Food and Agriculture Organization/World

 

Health Organization of the United Nations, Rome, 21 p.

Isman, M. B., Koul, 0.,  Luczynski, A.,  and Kaminski, J.

1990.  Insecticidal and Antifeedant  Bioactivities  of Neem Oils and Their Relationship to Azadirachtin Content.  J. Agric. & Food Chem. 38:1406-1411.

Janzen, D. H.

1967.  Synchronization of Sexual Reproduction of Trees Within the Dry Season in Central America.  Evolution 21(3):620-637.

Kapil, R. P.

1957.  The Length of Life and the Brood-Rearing Cycle of the Indian Bee.  Bee World 38(10):258-263.

Kohli, N.

1958-59.  Bee Flora of Northern India.  Indian Bee J. 20:113-118, 178-179.

Koul, O., Amanai, K.,  and Ohtaki, T.  

1987.  Effect of Azadirachtin on the Endocrine Event of Bombvx mori.  J. Insect Physiol. 33:103-108.

Koul, O., Isman, M. B., and  Kethar, C. M.

1990.  Properties and Uses of Neem, Azadirachta indica.  Can.  J.-Bot. 68:1-11.

Loke, J. H.,  Heng,C. K.,  Rejab, A.,  Basirun, N. ,  Mardi, H. C. A., Ooi,  P. A. C. (ed),  Lim , G. S.(ed), and Teng, P. S.

1992.  Studies on Neem (Azadirachta indica A. Juss) in Malaysia.  In Proceedings of the 3rd International Conference on Plant Protection in the Tropics. Malaysian Plant Protection Society Kuala Lumpur, Malaysia. 2:103-107.

Nair, P. K. K.

1965.  Pollen Grains of Western Himalayan Plants. 102  pp.  London, U.K.: Asia Publishing House.

Puri, H. S.

1999.  Neem the Devine Tree, Azadirachta indica.  182 pp.  Harwood Academic Publishers, The Netherlands.

Raju, A. J. S.

1998.  Bee Pollination in Azadirachta indica (Melicaceae).  Indian Bee J. 60(2):86

Ramachandran, S.

1937.  Beekeeping in South India. 2nd Edition, Bull.  Dep.  Agric.  Madras 37:78.

Roubik, D. W.

1989.  Ecology and Natural History of Tropical Bees.  514 pp.  Cambridge Tropical Biology Series, Cambridge Univ.  Press, Cambridge.

Schmutterer, H.

1990.  Properties and Potential of Natural Pesticides form the Neem Tree, Azadirachta indica..  Ann. Rev. Entomol. 35:271-97.

Singh, S.

1962.  Beekeeping in India.  New Delhi, India: Indian Council of Agricultural Research.

Subramaniam, K.

1979.  The Role of Forest Department in Developing Beekeeping in Western Ghat Areas of Maharashtra. Indian Bee J. 41(3/4):91-93. 

Tanzubil, P. B., and McCaffery, A. R.  

1990.  Effects of Azadirachtin on Reproduction in the African Armyworm (Spodoptera exempta).  Entomol.  Exp.  Appl. 57:115-121.

Trewari, D. N.

1992.  Monograph on Neem (Azadirachta indica A. Juss) .  279 pp.  Int. Book Distributors, Dehra Dun, India.

Vonderman, A. G.

1896.  Inlandsche Geneesmiddelen. (Translation:Local Traditional Medicine

 

of Indonesia).  889 p. Tijdschr. vanInl.  Geneesmiddelen, II.

 

Willemstein, S. C.

 

1987.  An Evolutionary Basis for Pollination. Ecology.  425 p.  E. J. Brill/Leiden   University Press, Leiden.