4种生物杀虫剂对石榴蓟马的致毒效应研究

为筛选防治石榴蓟马的高效、低毒和无污染的生物杀虫剂,采用浸渍法测定了4种生物杀虫剂对石榴蓟马不同虫态的毒力效应。结果表明：4种生物杀虫剂对两种石榴蓟马的毒力依次为：乙基多杀菌素>印楝素>苦参碱>除虫菊素。乙基多杀菌素对黄胸蓟马3龄若虫和成虫的LC50分别为8.550 mg/L和12.078 mg/L。对西花蓟马3龄若虫和成虫的LC50分别13.647 mg/L和20.185 mg/L。印楝素和苦参碱亚致死浓度均可引起两种石榴蓟马的化蛹率和羽化率显著下降（P<0.05）。表明乙基多杀菌素、印楝素和苦参碱均能对两种石榴蓟马种群有较好的抑制作用。     

水分影响印楝素及同系物降解动力学研究

研究水分对印楝素A、6-deacetylnimbin、6-deacetylsalannin、nimbin和salannin5种同系物稳定性的影响,并建立水分影响印楝素及同系物降解动力学模型。结果表明,水能加快印楝素A及同系物的降解,且降解率随着水分含量的增加而增大。     

3-羟基,12-羧基印楝素的制备、结构鉴定及生物活性测定

对印楝素进行水解反应,得到3-羟基,12-羧基印楝素,以浸叶喂食法研究了3-羟基,12-羧基印楝素对小菜蛾Plutella xylostella、斜纹夜蛾Spodoptera litura和棉铃虫Heliothis armigera的生物活性.结果表明,在室温敞开体系贮存15 d后,印楝素、印楝素干粉和印楝种子甲醇粗提物溶液中印楝素大部分降解,但溶液仍对斜纹夜蛾幼虫具有良好的毒杀活性.处理后24 和48 h,3-羟基, 12-羧基印楝素对斜纹夜蛾3龄幼虫的AFC50值分别为37.19 和 50.18 μg/mL.在3 μg/mL的剂量下处理后24 h,3-羟基,12-羧基印楝素对小菜蛾3龄幼虫的拒食率为 46.69 %;在5 μg/mL的剂量下处理后24 h,对棉铃虫3龄幼虫的拒食率为75.65 %;在3 μg/mL的剂量下处理后72 h,小菜蛾3龄幼虫的死亡率为61.28 %;在5 μg/mL的剂量下处理后72 h,棉铃虫3龄幼虫的死亡率为47.65%;在 2.0 μg/mL 的剂量下处理后72 h,棉铃虫3龄幼虫的体质量下降率为48.93 %;在1.0 μg/mL的剂量下处理后 72 h,斜纹夜蛾3龄幼虫的体质量下降率为41.18 %.     

印楝素与三种杀虫剂对小菜蛾的联合毒力作用

采用浸叶浸虫法,测定了印楝素与三种杀虫剂对小菜蛾的室内联合毒力作用,并筛选出了药剂的最佳复配比例。结果表明,印楝素：阿维菌素为2．3：1,共毒系数(CTC)为141．14,增效作用最为显著;印楝素：Bt为1：1,共毒系数为136．74;而印楝素与高效氯氰菊酯混配对小菜蛾表现为相加作用。     

棉铃虫5龄幼虫对棉酚和印楝素的味觉适应性行为研究

【目的】研究棉铃虫幼虫对棉酚和印楝素的味觉适应性行为,为棉铃虫的防治提供参考依据。【方法】采用叶碟法和味觉感受器切除法进行不同取食条件下棉铃虫5龄幼虫的取食选择行为试验。供试化合物为处理后终浓度为2mmol／L的棉酚和印楝素。【结果】正常人工饲料饲养的棉铃虫幼虫对棉酚和印楝素均十分敏感,取食对照叶碟量显著高于处理叶碟（P〈0．05）;切除中栓锥感受器后棉铃虫幼虫取食含棉酚或含印楝素的叶蝶量与正常叶碟有显著差异（P〈0．05）,而切除侧栓锥感受器后棉铃虫幼虫取食含棉酚或含印楝素的叶蝶量与正常叶碟差异不显著（P〉0．05）;以含有低浓度取食抑制素的人工饲料饲养的棉铃虫幼虫对棉酚和印楝素不敏感,取食对照叶碟量与处理叶碟无显著差异（P〉0．05）。【结论】棉酚和印楝素是棉铃虫幼虫的取食抑制素,侧栓锥感受器中含有对棉酚和印楝素敏感的味觉神经元,不同取食经历的棉铃虫幼虫对棉酚和印楝素具有行为适应性。     

Microbiological and Chemical Analysis of Neem (Azadirachta indica) Extracts: New Data on Antimicrobial Activity

The antimicrobial effects of extracts of neem seed (Azadirachta indica A. Juss.) were investigated using microbial growth inhibition assays. A laboratory-prepared neem seed extract along with a commercially available formulated product, were characterized using HPLC, and shown to be effective against a range of bacteria in an agar diffusion assay. The active ingredient,i.e., the unformulated seed extract of the commercial product, also showed activity and this was further investigated in a biochromatogram, using the sensitive bacteriumBacillus mycoides. Results showed antibacterial activity as three discrete inhibition zones that did not correspond to the R_f of the major neem metabolites, azadirachtin, nimbin and salannin. This suggests that these compounds were not antibacterial. The colony radial growth rates of the fungal pathogens that cause ‘take-all’ and ‘snow mould’ disease were both significantly affected when the commercial, unformulated, neem seed extract was incorporated into the growth medium. Experiments in liquid culture suggested that the effect was fungistatic. Conidial germination of the commercially important obligate pathogenSphaerotheca fuliginea (powdery mildew) was reduced to 11%. The results show that neem seed extracts possess antimicrobial activity with notable effects on some fungal phytopathogens. This Work demonstrates that neem seed extracts have potential for controlling both microbial and insect pests. http://www.phytoparasitica.org posting Sept. 16,2001.     

印楝种子品质性状的遗传多样性及稳定性分析

在云南印楝资源全面调查的基础上,以实生株系的种子为研究对象,运用HPLC技术分析种子印楝素组分含量,采用描述统计、方差分析、系统聚类和重复力估计,定性、定量分析印楝实生株系种子品质的遗传多样性及稳定性。结果表明:云南引种栽培印楝实生株系的种子品质存在广泛变异,种子印楝素A、B、AB含量和印楝素A与印楝素B含量比的变异幅度分别为0.28% 0.85%、0.04% 0.39%、0.37% 1.15%和1.698.25;种子印楝素A、B、AB含量分为3个类型:高含量型(azA ≥ 0.69%、azB ≥ 0.25%、azAB ≥ 0.92%)、低含量型(azA ≤ 0.44%、azB ≤ 0.10%、azAB ≤ 0.51%)和中等含量型(azA=0.68% 0.45%、azB=0.24% 0.11%、azAB=0.91% 0.52%);按此标准将高印楝素AB含量型分为"印楝素AB优异型(azAB ≥ 1.15%)"、"印楝素A优、B劣型"(azA ≥ 0.85%、azB ≤ 0.21%)、"印楝素A劣、B优型"(azA ≤ 0.67%、azB ≥ 0.39%)和"印楝素AB含量高型"(azAB=1.05% 0.92%);反映在重复力上,印楝实生株系种子印楝素A、AB的重复力分别为0.2063、0.3252,都属于"中"重复力性状。"印楝素AB优异型"即具有优异种子品质性状的植株是印楝药用原料林培育的繁殖材料;"印楝素A优、B劣型"和"印楝素A劣、B优型"即种子品质性状优缺点互补的植株是药用印楝品质育种的杂交亲本。     

印楝素、苦皮藤素防治茶卷叶蛾幼虫室内试验初报

开展了0.5%印楝素乳油、1%苦皮藤素乳油防治茶卷叶蛾室内药效试验。0.5%印楝素乳油800倍液和1%苦皮藤素乳油液750倍防治茶卷叶蛾效果良好,药后1、3、5 d防治效果分别为70.00%、85.19%、100%和66.67%、88.89%、95.83%,速效性也较好。初步试验结果表明,0.5%印楝素乳油、1%苦皮藤素乳油适用于茶园防治茶卷叶蛾幼虫。     

Breakdown of azadirachtin A in a tropical soil amended with neem leaves and animal manures

A field investigation was conducted to assess the breakdown of azadirachtin A in a tropical coastal savanna soil amended with neem leaves （NL） combined with poultry manure （PM） or cow dung （CD） using gas chromatography. Samples in polythene bags 15 cm long and 4.8 cm in diameter were randomly placed to a depth of 14 cm in the soil, and azadirachtin A concentration was assessed on days 0, 14, 28, 42, 56, 70, and 84. Azadirachtin A degradation in the soil followed first-order reaction kinetics with different half-lives obtained for varying combinations of the amendments. Higher neem amendment levels of 100 g gave shorter half-lives of azadirachtin A than the lower levels of 50 g. Within the 50 g NL group the additions of the poultry manure and the cow dung gave significantly shorter （P 〈0.05） half-lives of azadirachtin A than the sole neem amendment, whereas in the 100 g NL group only additions of 10 g CD and 10 g PM were significantly less （P 〈 0.05） than the sole neem amendment. Different changes resulting from the kind and quantity of animal manure added were observed in the half-lives of azadirachtin A. The 100 g NL group had significantly higher （P 〈0.05） moisture content, which, coupled with the likely differeaces in microbial biomass, could be the major factor responsible for variations in the half-llfe of the compound. Therefore, the quantity of the neem leaves applied and the addition of animal manure affected the breakdown of azadirachtin A in the soil amended with neem leaves.