| Azadirachtin is a highly oxidative tetracyclic triterpenoid from the neem tree( azadirachta indica A.Juss). It was proved that azadirachtin had antifeedant, deterrent, growth-disrupting, anti-ovipositional, fecundity-reducing properties on nearly 400 species farming, forest, storage and healthy pests which belong to 8 orders (lepidopterous, homoptera, diptera, coleopteran, thysanoptera, hymenoptera, orthoptera, acarina). It was revealed that the azadirachtin-based pesticides showed high efficiency in pest control, no effect on the natural enemies, less damage to the environment, low toxicity to mammals and the human beings, and had strong reaction on vegetative pests.However it's also an international difficulty problem to keep the stablity of neem active component in products.Thus we have systemly studied the analysis method of high performance liquid chromatography(HPLC) for the active compouds, the method of the isolation and purification, the biological activity against adults of Diaphania indica Motschulsky of azadirachtin, and the process of neem industrialization, identified the main components of fatty acids in neem oil, and offered a possible way to control stored-product insect pests. The main conclusions are as follows.1. Ethyl acetate crude extract was higer concentration of azadirachtin A. The crude extract was separated by Flash Column Chromatography and TLC. Thus, the pure azadirachtin A (>99%) and other homologous compounds (>95%) were obtained. Then, these chemical constructions were identified by UV, HPLC and LC-MS: azadirachtin-A, retention time 5.58min, molecular weight720; 6-deacetylsalannin, retention time 11.81 min, molecular weight 554; Nimbin,retention time 16.98 min,molecular weight 540;Salannin,retention time 18.58 min,molecular weight 596。2. Measured the amount of azadirchtins in neem crude extracts by reversed-phase HPLC. The extracts were analyzed on column C18(4.6mm×250mm), at room temperature, using acetonitrile-water(50:50 by volume) system with 1.0mL/min as the mobile phase, and detected at 215nm. Minimum detection limit was 0.5μg/mL. Retention time Aza-A was 5.58min.3. Studied the factors, which influence stability of azadirachtin, such as temperature, ultraviolet radiation ,pH value, resisting oxygen pharmaceutical and uv-absorbing additive. The test showed that weak acid condition was good for aza-A, otherwise, accelerated its degradation, and the most stable in mildly acidic aqueous solutions with pH4-6 at room temperature. when at the temperature of 4℃and 25℃, aza was stable, when temperature higher than 35℃, accelerated its degradation azadirachins decomposed with the growing of the temperature. Different water content make different inference between two samples, but the records became the same with high water content . UV light was an important inference of the degradation of aza. Degradations of aza-A in two samples were 92.95% and 89.11% after 2 days sustainable UV irradiation.Va and Vc could restrain the degradation of Aza-A and ethyl acetate extraction , Va was better than Vc; There was no more difference between Neem oil and alkali lignin which were another two selective light stabilizer, but the ability of anti-light was rising with large dose.4. Tested with 3 different neem extracts(neem SFE extracts,neem ethyl acetate extracts and oil) against Diaphania indica, the results showed that those extracts strongly deterred anti-feeding, growth inhibition and oviposition deterrent, and the toxicity against the low larva were better than the old ones. The bioactivities of those extracts increased with the growing of their dosage; Azadirachtin had some contact toxicity against to the low instar larva, but few to the the old ones.
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