大孔树脂对印楝素A吸附纯化的研究

通过比较5种大孔吸附树脂对印楝素A的吸附率和解吸率,成功地筛选出比较理想的树脂。研究结果表明:XAD-1180树脂对印楝素A有较好的吸附和解吸效果。并对其动态吸附、解吸性能进行了考察,发现较佳的吸附条件为:印楝素A质量浓度2.23 mg/mL(溶剂为30%甲醇-水溶液,以下同),流速1 BV/h,饱和吸附量4.5~5 BV;解吸条件为:以50%、60%、70%的甲醇-水溶液梯度洗脱。一次提纯产品的纯度为85.14%,经过二次提纯的纯度可达93.18%。纯化产物经HPLC-MS进一步确认为印楝素A。     

印楝素对柑橘木虱的毒力测定及田间防效试验

【目的】评价印楝素对柑橘木虱(Diaphorina citri)的室内毒力与田间防效,为柑橘木虱的生物防治提供科学依据。【方法】采用浸叶法和喷雾法测定印楝素对柑橘木虱三龄若虫和成虫的室内毒力及田间防治效果。【结果】在室内印楝素处理柑橘木虱三龄若虫1、3、7 d后LC_(50)值分别为2.77、1.14、0.61 mg/L;而16.0 mg/L印楝素处理木虱成虫4 d后死亡率仅为13.33%,与清水对照无显著差异。0.3%印楝素乳油800倍液喷雾处理后 1、3、7 d 对柑橘木虱田间防效分别为14.35%、49.56%和86.4%。【结论】印楝素对柑橘木虱若虫具有良好的毒杀活性,药后7 d 防治效果较好,但对成虫没有毒杀活性;印楝素在柑橘木虱若虫防治上具有良好的应用前景。     

4种化合物对荔枝蒂蛀虫的调控作用

在室内进行芳樟醇、薄荷酮、丁香酚和印楝素对荔枝蒂蛀虫成虫产卵驱避试验,同时研究化合物对荔枝蒂蛀虫卵的孵化和蛹的羽化过程的影响。在同一浓度下,对荔枝蒂蛀虫成虫产卵的驱避效果依次是丁香酚>芳樟醇>薄荷酮>印楝素。对荔枝蒂蛀虫卵的调控试验表明：0.3%印楝素对荔枝蒂蛀虫卵不具有熏杀作用,而其触杀作用最好;其他化合物对荔枝蒂蛀虫卵均具一定的熏杀和毒杀作用;随着化合物浓度的增加,熏杀和毒杀作用增强。对荔枝蒂蛀虫蛹的毒杀作用试验表明：用纯化合物处理蛹时,蛹茧立刻胀起,边缘皱缩,2天后观察,蛹体发黑,干缩死亡;稀释后的化合物处理蛹,蛹死亡率较低,仅为20.00%~26.70%。结果表明,芳樟醇、薄荷酮、丁香酚和印楝素对荔枝蒂蛀虫的不同虫态的发生均具有一定的抑制作用。     

Effect of some biorational insecticides on Spodoptera eridania in organic cabbage

BACKGROUND: To reduce pest attack, several biorational products are allowed for use on organic vegetables in Brazil. This study investigated eight biorational products applied singly or in combination against Spodoptera eridania Cramer in field plots of cabbage intercropped with coriander. The treatments were applied once a week over a 5 week period, beginning 34 days after transplanting. The evaluations consisted of counting the larvae of S. eridania on the day before and 7 and 21 days after spraying. The damage to leaves and cabbage head, the commercial weight of head and the percentage of head losses were evaluated.RESULTS: Leaf injury in plots treated with Beauveria bassiana and neem oil (Dalneem) yielded scores of 1.3 and 2.5 (scale ranging from 0 to 4) respectively, in comparison with a score of 3.6 from untreated plots. Head weight losses were 6.1, 5.3 and 4.9% with an aqueous extract of neem leaves, neem oil and B. bassiana respectively, compared with 24.6% lost from untreated plots.CONCLUSION: Dalneem, B. bassiana and the extract of neem leaves at 20% exhibited the best performance for control of S. eridania.     

Systemic applications of neem in the control ofCameraria ohridella, a pest of horse chestnut (Aesculus hippocastanum)

Systemic injection of neem (azadirachtin) was tested in the control of horse chestnut leafminer,Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae), a pest of horse chestnut trees (Aesculus hippocastanum L.: Hippocastanaceae). Three concentrations, 0.08, 0.15 and 0.25 g of active ingredient (a.i.) per cm of diameter at breast height (dbh), provided long-lasting insecticidal activity. The 0.15 and 0.25 g a.i. concentrations resulted in 100% pupae reduction in all generations; the 0.08 g a.i. concentration was effective against the horse chestnut leafminer for at least 23 weeks and led to 70–80% pupae reduction. Treated trees did not lose their leaves before winter. Neem applicationvia injection is cheap, with no environmental hazards, and thus this treatment is recommended for the control ofC. ohridella in horse chestnut trees. http://www.phytoparasitica.org posting Dec. 19, 2004.     

Effects of neem (Azadirachta indica) extracts onLeptocorisa chinensis under choice and no-choice conditions

Two extracts from neem (Azadirachta indica A. Juss. (Meliaceae)) seeds, azadirachtin and oil, and a mixture of neem oil and abamectin, were tested on second-instar nymphs of the rice bugLeptocorisa chinensis (Dallas) (Hemiptera: Alydidae). To clarify the effect of spraying coverage on bioefficacy of test materials, experiments were conducted under choice and no-choice conditions in field cages. In a choice test, treatment with the mixture of neem oil and abamectin was most effective in reducing the survival ofL. chinensis, followed by azadirachtin at 60 ppm, 30 ppm and 3% neem oil, whereas all treatments except neem oil caused 100% mortality within 3 weeks in a no-choice test. When second-instar nymphs had choices of treated and untreated plants within a treatment, no differences in yield and sum of dead and stained grains were found between those two choices, indicating that nymphs neither caused significant reduction in yield nor reduced the quality of untreated plants. Regardless of treatment, the difference in overall yield between treated and untreated plants under choice conditions was not statistically significant (P>0.05). Our results indicate that neem-based formulations, used alone or in combination with abamectin, have the potential to be integrated into the existing programs to control the rice bug. http://www.phytoparasitica.org posting Aug. 28, 2005.     

超声波用于强化有机溶剂提取印楝素

研究了用超声波强化有机溶剂提取印楝素的工艺过程，分别考察溶剂、料液比、超声波作用时间、超声波功率对提取率的影响实验发现，较理想的提取条件为：13．3g印楝种仁粉，料液比1：2，超声波功率200W；超声波作用时间与溶剂有关。甲醇15min、乙醇20min、乙酸乙酯10min；3种溶剂较佳提取率分别为0．3786％、0．3658％、0．2462％提取样晶利用高效液相色谱仪采用外标法测定提取物中印楝素的含量。实验结果表明，超声波强化提取与搅拌提取相比，不仅缩短了提取时间，而且提取率有所提高。     

云南省印楝种植及相关产业的发展现状

综述近年来云南省印楝种植及相关产业的发展动态,着重介绍了云南省在印楝种植及相关产业的发展方面取得的成就和印楝素生物农药在无公害农产品生产中的应用情况.     

Bioactive compounds from neem tissue cultures and screening against insects

Hairy root cultures have been derived from neem (Azadirachta indica A Juss, Family Meliacceae) using Agrobacterium rhizogenes and have been studied for the production of compounds with antifeedant effects on insects. Six-week-old hairy root cultures were extracted, and HPLC yielded fractions ranging from polar to non-polar compounds. High antifeedancy levels against the desert locust were observed in fractions(F) 2, 3 and 4 whilst F1 and F5 were not significantly antifeedant. Interestingly F3 did not contain any of the well-known neem chemicals while F2 contained azadirachtin and 3-tigloylazadirachtol and F4 nimbin and salannin. © 1999 Society of Chemical Industry     

Stability of the natural insecticide azadirachtin in aqueous and organic solvents

The natural insecticide azadirachtin is most stable in mildly acidic aqueous solutions between pH 4 and 6 at room temperature. It is unstable in mildly alkaline and strongly acidic solutions. It is stable when stored in neutral organic solvents at room temperature for months. While it is relatively stable to heating in the seeds or as a pure solid, it is rapidly destroyed or altered by heating in aqueous solution and methanol. In methanol at 90°C it is quantitatively converted to 3-acetyl-1-tigloylazadirachtinin. © 1998 SCI