The purpose of this paper is to inform the agricultural community about the resource available through the neem tree and it’s products, using scientific studies and drawing appropriate conclusions.
- The latin name of the neem tree is Azadirachtin indica.
- Neem originated in India.
- The primary active ingredient in neem products is azadirachtin.
- Neem is primarily used as a medicinal oil, fresh leaf tea/solution and dried leaf powder tea/solution.
- The leaves contain about 1.5 grams of azadirachtin per kilo, the seeds about 9 grams per kilo. Quantity may vary depending on area and season.
- Dried neem leaves will keep moths out of stored clothes.
- As an insect control measure, neem affects over 450 types of insects.
- There is no immediate death to insects when neem products are applied to plants.
- When ingested by larvae, neem may cause the insect to not pupate.
- Neem is an anti feedant for insects
- Neem reduces the fertility of female insects
- Neem inhibits larval development
- Neem is most effective against beetles and larvae, caterpillars and grasshoppers and locusts.
- Neem extracts have proved fatal to the aquatic snail Biomphalaria glabrata, a snail necessary in the life cycle of the parasite which causes schistosomiasis (bilharzia). An aqueous extract was fatal to Melania scabra, a vector to lung flukes which encysts in the lungs of various animals including people, causing debilitation and sometimes death.
- 1 kilogram of neem leaves, buried in the soil, per meter squared provides good nematode protection.
- Insects would rather starve to death than eat plants with traces of azadirtachtin. Pg 4, Neem …)
- Neem is very effective at controlling crop reducing nematodes. (Pg 13, Neem, …).
- The very deep roots of neem are good at extracting nutrients from poor soils, thus rejuvenating the soil. (Pg 13, Neem, ….).
- Care with dosage must be taken when applying neem to tomatoes, cabbage and onions as they have been negatively affected in trials. (Pg 20, Neem, …).
- Azadirachtin is similar to insect hormones called “ecdysones” which control metamorphosis, as well as the corpus cardiacum which controls hormone secretion in the insect, and acts as a blocker in these two areas. (Pg 32-33, Neem, …).
- In tests at the US Department of Agriculture, the soyabean plants which were sprayed with neem were not touched by the Japanese beetles, while the unsprayed were eaten to the veins. (Pg 4, Neem, …).
- Wheat, barley, rice sugarcane, tomatoes, cotton and chrysanthemums have the ability to absorb and distribute throughout their systems, the active ingredients. Thus they have been protected from insects for up to 10 weeks in this way. (Pg 8, Neem, … ). Also beans. (Pg 20, Neem, …).
- It seems unlikely that insects will be able to develop genetic resistance to neems complex blend of compounds. Several experiments have failed to detect any resistance build up. (Pg 8, Neem … ).
- 500 grams of seeds steeped in 10 liters of water creates a good pest control solution. Best method of extraction is to put seeds in a porous bag and pour the water over the crushed seeds, collecting the resulting liquid. (Pg 36, Neem, …).Neem works in the following ways – disrupting or inhibiting the development of eggs, larvae or pupae, blocking the molting of larvae or nymphs, disrupting mating and sexual communication, repelling larvae and adults, detering females from laying eggs, sterilizing adults, poisoning adults and larvae, deterring feeding, blocking the ability to “swallow”, sending metamorphosis awry at various stages and inhibiting the formation of chitin. (Pg 39-40, Neem, …).
- Neem oil protected chick pea seeds from the fungi of Rhizoctonia solani, Sclerotium rolfsii and Sclerotinia sclerotiorum and slowed the growth of Fusarium oxysporum; neem failed to kill the fungi Aspergillus flavus but completely stopped the production of aflatoxins. (D. Bhatnagar, US Department of Agriculture.) (Pg 53-54, Neem, …).
- Neem leaves and seeds kernels added to earthworm containing soil, increased the number of young produced by 25%. (Pg 58, Neem, …).
- Margosan-O, a product approved for use in the US, has passsed 13 safety tests required by the Environmental Protection Agency (EPA). It contains 3,000ppm of azadirachtin, plus/minus 10% and is approved for 19 insects in greenhouses, commercial nurseries, forests and homes.
Perhaps the most important agricultural application in Niger involves point number 24. The solution noted can be applied as follows to control stem borers in pearl millet, sorghum and maize (corn). At the first signs of feeding, the 10 liters of solution can be used to treat 4,000 plants by putting 2.5 ml in the top (whorl) of each plant. This procedure should be done 10 days later and again 10 days after that. Three applications should be sufficient. This method has doubled pearl millet production in some experiments.
Collecting seeds could be viewed as a family responsibility as everyone benefits from the results. This is not a physically strenuous activity.
The conclusions we can draw from this vital information are many. Neem has an important role to play in Nigerien agriculture due to it’s readily available nature and varied means of insect control. An understanding of its means of control is important as it does not kill on contact, giving instant gratification. However, its means of control are much more environmentally sensitive.
Decisions regarding the production of neem trees as a crop will need to be made in order to fill the demand for agricultural products.
Many of the safety related studies noted here were performed by the neem oil industry and apply to our application as the active ingredients are the same.
Footnote – The references in this material to Neem, …, refer to the book titled “Neem, A Tree for Solving Global Problems”, published by National Academy Press, 1992.
Research and preparation of this presentation was by Tim Wise, January 2012, as part of my work with SSCS, Maradi, Niger.