Detection of a related difference in efficacy of azadirachtin treatments for the control of whiteflies on Gerbera jamesonii by testing for interactions in generalised linear models

BACKGROUND: Within a project cluster, systemical effects of two neem treatments (Neem Azal? U and Neem Pellet) on the number of Trialeurodes vaporariorum (Westw.) in Gerbera jamesonii Flori Line Maxi were investigated. In order to minimise adverse ecological effects of a product, a new plant protection product can be declared as superior to a reference if it shows the same or a higher effect at a lower dosage. RESULTS: Based on a negative binomial model, the efficacy of the two treatments is compared by applying a user‐defined interaction contrast in a multiple‐contrast test framework. The corresponding calculation of simultaneous confidence intervals for the ratio of model parameters provides conclusions about statistical significance and biological relevance. The validity of the approach is shown by a small simulation study. As a result of the experiment, besides a significant difference between two negative control treatments, no significant difference between the efficiency of the two neem treatments (Neem Azal? U and Neem Pellet) could be detected. CONCLUSIONS: Simultaneous confidence intervals for linear combinations of parameters of generalised linear models provide a useful way to compare the efficiency of two plant protection products. The results for the azadirachtin experiment indicate that large differences between any application effects of either Neem Azal? U or Neem Pellet cannot be expected. Copyright © 2009 Society of Chemical Industry     

Green peach aphid,Myzus persicae (Hemiptera: Aphididae), reproduction during exposure to sublethal concentrations of imidacloprid and azadirachtin

BACKGROUND: Resurgence of insect pests following insecticide applications is often attributed to natural enemy disturbance, but hormesis could be an alternative or additional mechanism. Green peach aphid, Myzus persicae (Sulzer), is an important insect pest of many crops worldwide that may be exposed to sublethal insecticide concentrations over time. Here, the hypothesis that exposure to low concentrations of imidacloprid and azadirachtin can induce hormetic responses in M. persicae is tested in the laboratory. RESULTS: When insects were exposed to potato leaf discs dipped in sublethal concentrations of insecticide, almost all measured endpoints—adult longevity, F1 production, F1 survival and F2 production—were affected, and a statistically significant (P < 0.05) stimulatory response was recorded for F2 production following exposure to imidacloprid. No other measures for hormesis were statistically significant, but other trends of hormetic response were consistently observed. CONCLUSIONS: Given that variable distribution and degradation of insecticides in the field would result in a wide range of concentrations over time and space, these laboratory experiments suggest that exposure to sublethal concentrations of imidacloprid and azadirachtin could stimulate reproduction in M. persicae. Copyright © 2008 Society of Chemical Industry     

印楝素对斜纹夜蛾幼虫取食行为的影响

研究了经印楝素处理后斜纹夜蛾［Ｓｐｏｄｏｐｔｅｒａｌｉｔｕｒａ（Ｆａｂｒｉｃｉｕｓ）］５龄幼虫的取食行为．结果表明：斜纹夜蛾５龄幼虫２４ｈ内发生的取食活动和取食间间隔的次数减少,平均每次取食活动和取食间间隔持续的时间延长;在每次取食活动中,用于取食的时间明显减少,这主要是因为在每次取食活动中,取食内间隔的次数增加了,并且取食内间隔的时间也延长了．所有上述有关取食行为的指标,处理虫与对照虫之间均存在显著或极显著的差异．     

印楝素对马铃薯甲虫的控制作用

为探讨植物源杀虫剂印楝素对马铃薯甲虫的防治作用,采用叶碟法测定印楝素乳油对其成虫的拒食作用,并通过药效试验测定印楝素乳油对马铃薯甲虫的控制效果。结果显示,印楝素对马铃薯甲虫成虫有较强的非选择性拒食作用,且拒食率随取食时间的增加而升高。在取食36 h后,浓度为6、7.5、10、15和30 mg/L印楝素的拒食率分别为55.5%、59.1%、53.4%、76.1%和63.3%,拒食率与浓度无显著相关性;但印楝素对马铃薯甲虫的选择性拒食率较低,各浓度处理间均无显著差异,取食36 h时,选择拒食率约20%;在田间10 mg/L印楝素溶液施药1 d和3 d后,虫口减退率分别为26.52%和50.76%,显著高于对照组,施药9 d后,马铃薯甲虫的校正防治效果为48.86%。表明印楝素对马铃薯甲虫有一定的控制效果。     

5种杀虫剂和黄瓜新小绥螨对棉田朱砂叶螨的协调防治

为协调使用杀虫剂及害虫天敌,本文测定了阿维菌素、印楝素、苦参碱、除虫菊素和吡虫啉5种常用杀虫剂分别与天敌黄瓜新小绥螨(原名胡瓜钝绥螨)对棉田朱砂叶螨的联合防治效果。结果表明:1.8%阿维菌素EW(1∶8 000)处理6d后释放黄瓜新小绥螨对朱砂叶螨的防治效果最佳,20d后相对防治效果高达96.63%;其次是0.3%印楝素EC(1∶250)处理7d后释放黄瓜新小绥螨,1d和20d后防效分别为59.7%和90.16%;0.5%苦参碱AS(1∶2 000)处理6d后释放黄瓜新小绥螨,20d后相对防治效果达到82.65%。本研究为朱砂叶螨可持续防控提供了可选方案,为延缓抗药性产生提供了研究思路。     

印楝素乳油对水稻二化螟作用方式的研究

以不同稀释度的印楝素乳油处理水稻茎秆,探讨其对水稻二化螟的作用方式。结果表明:印楝素0.750、0.500、0.375、0.300和0.250μL·L-1的浓度处理稻茎,对二化螟拒食率分别为70.82%、65.74%、58.64%、36.69%和23.61%。印楝素乳油处理水稻茎秆饲喂3龄幼虫,0.750和0.500μL·L-1的高浓度处理,幼虫分别于6、12d全部死亡;0.375、0.300和0.250μL·L-1的低浓度处理,对其生长发育有明显的抑制作用。印楝素对二化螟成虫具有较强的产卵忌避作用,10μL·L-1的浓度对成虫产卵忌避率达88.6%。室内毒力测定还表明二化螟蚁螟对印楝素乳油比较敏感。     

印楝幼苗对不同水分和光照条件的生理生态学响应

为了揭示印楝幼苗生长及代谢对不同水分和光照条件的响应规律,以0.5年生印楝半同胞家系实生苗为材料,设置4个水分水平（分别占田间持水量的60%~65%、40%~45%、30%~35%和20%~25%）与3个光照水平（分别是自然光照的100%、75%和50%）共12个组合的盆栽试验,分析不同水分及光照条件下生长指标、形态指标、生理指标及印楝素含量的变化情况。结果表明,自然光照、田间持水量为60%~65%的条件更有利于印楝幼苗的生长,干旱胁迫和遮光对印楝苗高、地径、生物量以及叶片发育均会产生抑制作用,且遮光的抑制程度明显大于干旱;在干旱胁迫条件下,印楝可通过大量合成可溶性蛋白质、游离脯氨酸及可溶性糖等初生代谢产物以及增加根茎比来提高植株干旱适应能力;在遮光条件下,印楝主要初生代谢产物可溶性蛋白质、可溶性糖、游离脯氨酸的合成受阻,其次生代谢产物印楝素的积累减少;在重度干旱胁迫条件下,遮光在一定程度上可以缓解干旱对印楝幼苗生长带来的不利影响;干旱和遮光的交互作用遵循“促进理论”,不支持“独立影响理论”。研究表明,印楝幼苗在生长过程中表现出较大的干旱适应范围及较强的光照依赖性。因此,在幼苗培育过程中要尽可能提供最大光照强度。此外,充足光照条件下适当干旱胁迫有利于印楝初生代谢产物与次生代谢产物的积累,这可作为生产上提高印楝素含量的一个潜在措施。     

印楝素制剂对小菜蛾毒杀和生长发育抑制作用的研究

印楝素制剂对小菜蛾３龄幼虫具有较好的毒杀和生长发育抑制作用。小菜蛾３龄思虫连续４ｄ饲喂经１５ｍｇ／Ｌ印楝素制剂处理的叶片时，幼虫和蛹死亡率达８４．１２％，化蛹率，羽化率和正常羽化的雌虫生殖力随处理浓度升高而迅速下降；对多种杀虫剂产生抗性的小菜蛾田间品系和敏感品系的毒力无显著差异。其ＬＣ５０值分别为３６．９０ｍｇ／Ｌ和２８．７７ｍｇ／Ｌ。     

微波辅助法提取印楝素的研究

介绍了一种有效利用微波辅助从印楝(Azadirachta indica A.Juss)种仁中提取印楝素的方法。通过考察辐射时间、溶剂、物料比以及辐射功率等因素对提取率的影响，得出结论为：预处理过的印楝种仁粉末6.65g(相当于印楝种仁10g)，以甲醇做溶剂、微波功率210w、物料比1：3(g／mL)、辐射时间为3min*3次，提取率最高。与传统的磁搅拌法相比，该方法不仅工艺简单，而且可以提高产率，缩短提取时间。用高压液相法定量地测定了所提取印楝素的含量，其提取率可达0．519％．