Azadirachtin is an amazingly complicated compound found in different components of the Neem Tree (Azadirachta indica) where it defends against insect infestation. It is a steroid of the tetranortriterpenoid class, with many elaborate functional groups. It has a molecular weight of 720.71 grams/mole and a molecular formula: C35H44O16. Due to its size and intricacy, laboratory synthesis has only recently been achieved. The compound is most concentrated in seeds which have about 0.2 to 0.8 azadirachtin by weight.
Azadirachtin Blocks Insect Growth and Maturation
Azadirachtin is an effective insecticide, inhibiting the growth, fertility, and feeding ability of a wide range of arthropods. It does this by interfering with the function of a hormone (ecdysone) that directs the normal shedding of their chitin exoskeletons. Shedding must occur for growth and maturation of arthropods since their volume is expanding. When this is inhibited, they tend to die quickly.
An Ideal Insecticide
Azadirachtin is water and alcohol soluble, and now easily obtained through commercial synthesis and plant extraction methods. Residues generally last 4-6 days and the compound is degraded by ultra violet radiation and rain.
The following properties make azadirachtin an ideal insecticide:
- Non-toxic to mammals
- Does not harm the enemies of pests
- Relatively inexpensive
- Easily obtained by plant extraction and commercial synthesis
- Biodegradable with no toxic byproducts
- Plant source is not destroyed
Commercially Available Worldwide
Commercially, this compound is now available in several stable forms, and has proven to be effective against a range of insects. Insect susceptibility and death appear to be dose-dependent, with marked effect on growth as opposed to feeding inhibition. A negative aspect of azadirachtin is that it degrades quicker than many other commercial pesticides and thus, must be reapplied more often.
Additional Resources
Calvo and J. M. Molina, “Effects of a commercial neem (Azadirachta indica) extract onStreblote panda larvae,” Phytoparasitica 31, no. 4 (8, 2003): 365-370.
Schmutterer, “Potential of azadirachtin-containing pesticides for integrated pest control in developing and industrialized countries,” Journal of Insect Physiology 34, no. 7 (1988): 713-719.
Senthil-Nathan, S., Kalaivani, K., Murugan, K., Chung, G. (2005). "The toxicity and physiological effect of neem limonoids on Cnaphalocrocis medinalis (Guenée) the rice leaffolder". Pesticide Biochemistry and Physiology 81: 113.
Gemma E. Veitch, Edith Beckmann, Brenda J. Burke, Alistair Boyer, Sarah L. Maslen, Steven V. Ley (2007). "Synthesis of Azadirachtin: A Long but Successful Journey". Angewandte Chemie International Edition 46 (40): 7629.
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