印楝素对果蝇厌恶性味觉记忆的诱导及多巴胺能神经元的影响

【目的】明确印楝素是否能诱导果蝇产生厌恶性味觉记忆,并探讨多巴胺信号在这种记忆形成中的调控作用。【方法】利用印楝素诱导果蝇产生短期厌恶性味觉记忆,并通过昆虫口器伸展反应测试诱导结果;采用压力注射给药方式及果蝇全脑膜片钳记录,研究印楝素对果蝇脑内不同亚群多巴胺能神经元兴奋性及受体电流的影响。【结果】印楝素A及印楝素干粉均能显著抑制果蝇口器伸展的概率,口器伸展反应(PER)分别为60.34%和17.24%,(P0.007),并且干粉的效果更加明显;印楝素对不同亚群的多巴胺能神经元的兴奋性有不同的作用,PPL1、PAM和PPM2亚群兴奋性呈现增加趋势,其中PPL1亚群兴奋性改变最为显著;印楝素对多巴胺D1受体具有激动效应,这种激动效应可被D1受体特异性拮抗剂抑制。【结论】印楝素可以诱导果蝇产生厌恶性味觉记忆,这种记忆受果蝇脑内多巴胺能信号的调控。     

印楝素亚致死浓度对烟粉虱实验种群的生物活性

在室内条件下,以2个亚致死浓度（0.15和0.30mg/L）喷雾处理烟粉虱1、5日龄卵,明确了印楝素亚致死浓度对烟粉虱实验种群发育、存活、繁殖均具有显著的抑制作用。其中,印楝素处理1日和5日龄卵分别使幼期（卵至成虫羽化）发育历期延长0.92至2.84d,幼期存活率降低了56.3%至89.6%,若虫虫体长宽减小,雌成虫寿命降低29.8%至48.6%,平均单雌产卵量降低49.8%至72.5%。清水对照、0.15mg/L和0.30mg/L印楝素溶液处理1日龄卵,烟粉虱实验种群的内禀增长率分别为0.227、0.0742和0.060,净增殖率依次为36.40、7.29和5.33;处理5日龄卵时两者分别为0.126、0.114和0.059与39.192、3.59和4.93。     

取食量对斜纹夜蛾生长发育的影响

通过控制取食量的方法模拟拒食作用,研究了不同取食量和印楝素拒食处理对斜纹夜蛾幼虫生长发育的影响．结果表明,食物量的减少对斜纹夜蛾幼虫的生长发育有明显的抑制作用．对斜纹夜蛾3龄幼虫进行控制取食量处理,发现随取食量的降低,生长抑制作用增大,试虫的发育历期延长,死亡率增高,但化蛹率和羽化率所受影响不大．用不同浓度的印楝素处理斜纹夜蛾3龄幼虫,发现随印楝素浓度的增高,对斜纹夜蛾幼虫的生长抑制作用越明显．印楝素拒食处理使试虫的发育历期延长,死亡率升高,这与控制取食量的结果相似,但印楝素使试虫的化蛹率和羽化率明显降低,这与控制取食量的结果有差别．     

Antifeedant effect of commercial chemicals and plant extracts against Schistocerca americana (Orthoptera: Acrididae) and Diaprepes abbreviatus (Coleoptera: Curculionidae)

BACKGROUND: The deterrent effect of seven commercial compounds against Schistocerca americana (Drury) nymphs and Diaprepes abbreviatus L. adults, two important citrus pests, was investigated. Extracts of three Florida local plants were also tested as deterrents. Antifeedant activity was assayed using a leaf‐disk bioassay in choice and no‐choice tests. The residual activity of the commercial compounds that significantly deterred the insects was assayed by applying them to foliage of citrus plants exposed to three time intervals of sunlight. RESULTS: Sabadilla, azadirachtin and ryanodine effectively deterred S. americana, whereas rotenone, sabadilla and ryanodine reduced the feeding activity of D. abbreviatus. Methanol and methylene chloride extracts of Ceratiola ericoides Michaux deterred D. abbreviatus, but only methylene chloride extract dissuaded S. americana. Methanol extract of Ardisia crenata Sims functioned as a feeding deterrent against both S. americana and D. abbreviatus, but only the latter species was deterred by methylene chloride extract of A. crenata. Extracts of Illicium parviflorum Michaux ex Ventetat only dissuaded the insects in choice bioassays. Rapid loss of effectiveness was observed under field conditions. Sabadilla was the only compound that maintained its antifeedant properties in the field, but only against S. americana. CONCLUSION: Based on their deterrency, some of the commercial products and plant extracts have potential for use as substitute crop protectants against the pest species tested. Copyright © 2011 Society of Chemical Industry     

Note: Toxicity of some insecticides onBracon hebetor under laboratory conditions

Insecticides which were environmentally friendly and the least toxic, were screened against a laboratory strain ofBracon hebetor (Say) (Hymenoptera: Braconidae) for their suitability for release in IPM of cotton. Concentrations ranging from 1 to 1000 ppm of the formulated insecticides in acetone were applied in glass vials and also by a leaf method, whereby cotton leaves were dipped in aqueous solutions of the same concentrations of insecticides. Adult parasitoids were exposed in both methods. According to the LC₅₀ at 24 h exposure, Λ-cyhalothrin and spinosad were the most (7 and 5 ppm) and least (263 and 225 ppm) toxic in the vial and the leaf method, respectively, toB. hebetor. The possible use of the parasitoid for IPM of cotton is discussed. http://www.phytoparasitica.org posting July 20, 2006.     

Managing Strawberry Pests with Chemical Pesticides and Non-Chemical Alternatives

ABSTRACT

Western tarnished bug or lygus bug (Lygus hesperus) is a major pest of California strawberries causing significant yield reduction. Other common insect pests include aphids (Chaetosiphon fragaefolii and Myzus persicae), greenhouse whitefly (Trialeurodes vaporariorum), and western flower thrips (Frankliniella occidentalis). Growers mainly depend on chemical pesticides for managing these pests. Limited control with some of the available chemical pesticides and the risk of resistance development due to their repeated use warrant a strong integrated pest management program where multiple tools can be utilized. Field studies conducted in commercial strawberry fields from 2012–14 in Santa Maria with an emphasis on managing L. hesperus demonstrated the potential of botanical and microbial pesticides. Replacing one or more applications of chemical pesticides with botanical and microbial alternatives and using them in different combinations can make a significant contribution to a sustainable management strategy.     

Cell Suspension Culture of Neem Tree

The establishment of suspension culture system for neem (Azadirachta indica A. Juss) cells and the suspension culture condition was studied. It shows that the neem cell suspension culture system was best in B5 liquid medium, 2.0~4.0mg/L NAA with direct spill method. Based on the integrated analysis of cell biomass, Azadirachtin content and productivity, the optimum culture conditions were B5 liquid medium, 2.0-4.0 mg/L NAA, 3% sucrose at 25 ℃. The optimum rotating speed of the shaker and broth content depends on the size of the cultural vessel and loading volume.     

Actions of azadirachtin,a plant allelochemical,against insects

Investigations of the antifeedant mode of action of azadirachtin and four synthetic analogues, 22,23-dihydroazadirachtin, 3-tigloylazadirachtol, 11-methoxydihydroazadirachtin and 22,23-bromoethoxydihydroazadirachtin have revealed that both polyphagous and oligophagous insects are behaviourally responsive to azadirachtin, with the most responsive species being able to differentiate extremely small changes in the parent molecule. In Lepidoptera the antifeedant response is correlated also with increased neural activity of the chemoreceptors. When locusts are treated on crop plants, the antifeedant and physiological actions of azadirachtin and analogues work in concert and result in feeding deterrence, growth and moulting aberrations and mortality with the same order of potency as for antifeedancy. Specific binding studies using [³H]dihydroazadirachtin carried out on locust testes and Spodoptera Sf9 cells have shown that the competitive binding of the different analogues of azadirachtin to these binding sites occurs in a similar order of potency to that found with antifeedant and IGR bioassays. This suggests a causal link between specific binding to membrane proteins and the ability of the molecule to exert biological effects. © 1998 Society of Chemical Industry     

印楝素悬浮剂的制备及拒食活性测定

研究了阴离子和非离子表面活性剂复配体系对印楝素悬浮剂悬浮率的影响,采用水基悬浮剂悬浮率、分散性、粘度、粒度等作为控制指标,确定了w=2%印楝素悬浮剂的最佳配方:表面活性剂(w=10%)为阴离子表面活性剂农乳500、木质素磺酸钙和非离子表面活性剂农乳600以质量比2∶ 1∶ 2复配;增稠剂为w=1%白炭黑;防冻剂为w=3%的乙二醇;抗泡剂为w=1%的硅酸;其余为去离子水.测定了w=2% 印楝素悬浮剂和w=0.3%印楝素乳油对斜纹夜蛾Spodoptera litura的拒食活性,结果表明,2种印楝素制剂对斜纹夜蛾的拒食活性相当.     

水分对印楝素稳定性的影响

报道了水分对印楝素稳定性的影响.印楝甲醇抽提物和印楝素纯品试验表明:水分是促进印楝素降解的一个重要因素.当水与甲醇组成的混合溶剂中水的体积分数为1 8%、3 5%、5 2%、6 8%、8 3%时,在(54±1)℃保存14d后,印楝甲醇抽提物中的印楝素分别降解40 4%、45 4%、47 3%、50 1%、56 2%,大多高于对照(甲醇溶液)分解率(42 1%);印楝素纯品分别降解43 3%、47 2%、53 4%、51 9%、59 5%,都高于对照(甲醇溶液)分解率(42 0%).在(0±1)℃保存14d后这4种溶剂中的印楝素都基本不降解,在室温下保存14d后都只有少量降解.纯水中的印楝素在(54±1)℃下最多保存7d即全部降解.