Neem Oil......why it works and what it does

Discussion in 'Organic Growing' started by Organic Rasta, Sep 12, 2006.

  1. Organic Rasta

    Organic Rasta Registered+


    Neem contains several active ingredients, of which the most important is Azadirachtin. It has been estimated that Azadirachtin accounts for up to 90% of the bioactivity of neem, but there is so much synergism at work in this pesticidal cocktail of four major and twenty minor active components, that it is impossible to quantify a percentage.
    Neem compounds bear no resemblance to synthetic pesticides. They are composed only of carbon, oxygen and hydrogen and contain none of the chlorine, phosphorus, sulfur or nitrogen atoms found in synthetic chemicals. Chemically neem resembles steroid compounds like cortisone and oral contraceptives, and there is a very different mode of action compared to the conventional “Wham, bam, thank you Maam!” of the toxic knockdowns. In most cases neem extracts are not knockdown killers. Instead they create hormonal disruption, which prevents the insect from feeding, breeding or metamorphosing. It is a far more subtle process, which eventually prevents the insect from causing further damage. It is a hormonal shutdown rather than an instant knockdown.


    The active compounds in neem belong to a general class of natural products called ‘Triterpenes’, or more specifically, ‘limonoids’. There are at least ten limonoids in neem, but the most researched of these are Azadirachtin, Salannin, Meliantriol and Nimbin.

    Azadirachtin is the most significant of these. Thirty years of research suggest that Azadirachtin is one of the most potent growth regulators and feeding deterrents ever tested. It is in fact so potent that quantities as low as 1 ppm (part per million) will totally repel some insects. Meliantriol and Salannin are powerful feeding inhibitors, while Nimbin has been found to have antiviral activity.

    Neem compounds have a very similar shape and structure to several critical insect hormones. This look-alike feature tricks the insects’ bodies into absorbing the neem compounds as if they were the vital hormones. The neem infiltrators shut down the endocrine systems, and the hormonal chaos that follows sees populations plummet.
  2. Organic Rasta

    Organic Rasta Registered+

    Neem Oil ...con't



    Neem limonoids produce seven distinct modes of action, and they include the following:
    1) Feeding Deterrence: This is the most commercially significant property of neem. The presence of Azadirachtin, Salannin and Melantriol on the leaf surface disrupts the gut of leaf-eating insects, creating the equivalent of a vomiting sensation. The associated feeding deterrence is so profound that, after experiencing the sensation, many species will never eat again.

    2) Insect Growth Regulation: Ecdysis or moulting is the shedding of skin to facilitate the growth stages of larvae or nymphs, and it is governed by the enzyme Ectyzone. Neem suppresses Ectyzone, and the insect becomes trapped in the larval stage, eventually causing death. If there are insufficient neem triterpenes present, the larvae may enter the pupal stage, but dies soon after, and if in the presence of very low neem concentrations, the adult emerges from the pupal stage sterile and malformed.

    3) The disruption of mating and sexual behaviour: It is not known if independent hormonal disruption is responsible for this complete confusion in mating routines or if the insects just feel so bad that they are sexually incapacitated. Whatever the cause, the end result is a population retarding effect and is probably quite hilarious.

    4) Oviposition Deterrence: Neem also reduces pest populations by deterring females from laying eggs - a phenomenon called oviposition deterrence.

    5) Repulsion: Neem oil contains several sulfur-like compounds that can repulse insects in much the same way as garlic sprays. Some insects are particularly susceptible to this repulse response, while others cannot detect neem by taste and do not find it repulsive.

    6) Adult sterilisation: Most susceptible males are sterilised by neem compounds, and many of the female species are similarly affected. The sterilisation of eggs has also been recorded.

    7) The poisoning of larvae and adults: As previously mentioned, neem does not have a universal knockdown capacity. However, there are some species, including mosquito larvae, fruitfly and headlice, which are killed on contact.
    There are also other less important modes of action, which include the blocking of the ability to ‘swallow’ and the inhibition of the formation of chitin (the hard section covering the exosceleton).


    Some 390 insect species are affected by neem extracts, including many that are resistant to conventional pesticides. There is such a complex interrelationship between the many components of the neem compound that, to date, there has never been a recorded case of developed neem resistance. This may not prove the case when refined Azadirachtin products hit the market in the future. When man tries to dilute and simplify natural phenomena, there are often unanticipated consequences.
  3. Organic Rasta

    Organic Rasta Registered+

    Imagine a soil drench.......1 Teaspoon (5 ml.) to a quart (Liter) of water is the usual recommendation... as a "Soil Drench."
    A few drops of liquid dish soap to emulsify the solution.

    If using Soil/Organics and biological activity is still desired, do not use dishsoaps labeled antibacterial as they contain the chemical "Triclosan" which is very effective as an anti-bacterial, anti-Fungal agent)

    Research has shown that neem has some systemic action in plants, meaning that the plants absorb it. When soils, neem can be taken up by the roots of some plants and translocated to other parts of the plant. Neem may remain active in the soil up to four weeks, depending on soil conditions.

    When neem is applied to plant foliage, its systemic action is limited—new foliage must be sprayed periodically for adequate protection.
  4. Organic Rasta

    Organic Rasta Registered+

    Adding to the convo....

    and adding to the conversation.......


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