曼陀罗不同提取液对玉米螟的触杀活性研究

应用均匀设计法研究了曼陀罗全草的不同提取液对玉米螟的触杀作用。结果表明：乙醇浸提液对玉米螟具有较高的触杀作用,对玉米螟72 h的致死浓度(LC₅₀)为17.328 1 mg/mL,触杀致死率为96.1%;乙醚浸提液和水蒸气蒸馏液对玉米螟的触杀作用不显著。     

独角莲不同提取液对大豆蚜虫的生物活性及活性浓度的筛选

基于均匀设计法研究了独角莲球根茎的不同提取液对大豆蚜虫的触杀和拒食作用.结果表明:乙醇浸提液对大豆蚜虫具有较高的触杀活性.水蒸汽蒸馏液对大豆蚜虫具有较强的拒食活性.乙醇浸提液对大豆蚜虫48h的致死中浓度(LC50)为8.71 mg·mL-1,水蒸汽蒸馏液对大豆蚜虫24、48 h的拒食中浓度(AC50)分别为8.66、7.93 mg·mL-1.乙醚浸提液对大豆蚜虫的触杀和拒食作用不显著.60 h的同时触杀和拒食活性浓度筛选的结果表明,乙醇浸提液24.1545 mg·mL-1和水蒸汽蒸馏液23.014 nag·mL-1联合使用对大豆蚜虫同时触杀和拒食活性最好,死亡率达100%.     

莰酮对蚜虫生物活性的研究

进行了樟树(CinnamomumcamphoraL.)中的莰酮(CamphorC10H160)对蚜虫的触杀、熏蒸毒力和拒食活性研究。结果表明,处理后24h莰酮对菜缢管蚜、桃蚜和棉蚜触杀作用的LD50分别为3.12×10-3,2.04×10-3,0.68×10-3 ng/头,熏蒸作用的LC50分别为3.44,2.56,1.06mg/L,拒食作用的AFC50分别为3.34,2.98,1.32mg/L。经回归和相关分析,处理浓度与作用效果相关性均达到极显著或显著水平。莰酮在田间防治菜缢管蚜的效果显著。     

新入侵害虫海枣异胸潜甲防治药剂的室内筛选

海枣异胸潜甲是一种新入侵并爆发成灾的棕榈科植物害虫,筛选出具有较高毒力水平的化学药剂防治该虫迫在眉睫。本研究采用浸渍法测定了11种杀虫剂对海枣异胸潜甲幼虫的毒力。试验结果表明,较低浓度的阿维菌素(10 mg/L,24 h)、氟虫腈(10 mg/L,24 h)、甲氨基阿维菌素(10 mg/L,72 h)和啶虫脒(10 mg/L,48 h)对海枣异胸潜甲幼虫的触杀致死率达100%,其24 h的LC50分别为0.7、2.28、4.02、5.61 mg/L;较高浓度的高效氯氰菊酯(200 mg/L,48 h)、氯虫苯甲酰胺(400 mg/L,48 h)和氯氟氰菊酯(400 mg/L,72 h)对海枣异胸潜甲幼虫的触杀致死率达100%;敌百虫、多杀菌素、虫酰肼和氟啶脲的触杀致死率相对较低。因此,可选用阿维菌素、啶虫脒、甲氨基阿维菌素和氟虫腈作为当前防治海枣异胸潜甲主要防治药剂。      

鱼藤酮对椰心叶甲的生物活性

研究鱼藤酮对椰心叶甲的杀虫活性,采用胃毒法和触杀法测定鱼藤酮对椰心叶甲5龄幼虫的生物活性和采用触杀法测定鱼藤酮对椰心叶甲卵的毒杀活性。结果表明,鱼藤酮对椰心叶甲5龄幼虫具有很强的毒杀作用,24h和48h的LC50值分别为5.315、1.681mg/L。对椰心叶甲卵也有显著的毒杀作用,在供试浓度为5～20mg/L时,对椰心叶甲卵孵化率和幼虫存活率均在50%以下。鱼藤酮对椰心叶甲5龄幼虫的触杀作用较差,其24h和48h的LC50值分别为23.68、16.24mg/L。     

外源硫化氢对盐碱胁迫下裸燕麦矿质元素吸收、运输和分配的影响

为了解硫化氢(H₂S)对盐碱胁迫下裸燕麦矿质元素吸收、运输和分配的调控效应,以裸燕麦品种定莜9号为材料,采用盆栽砂培试验,研究抽穗期喷施50 μmol·L_-1 H₂S供体硫氢化钠(NaHS)溶液对50 mmol·L_-1盐碱混合胁迫下裸燕麦根、茎和叶中29种矿质元素和4种阴离子含量及矿质元素选择性运输、质膜Na⁺/H⁺逆向转运蛋白基因 SOS1和液泡膜Na⁺/H⁺逆向转运蛋白基因 NHX1表达和植株生物量的影响。结果表明,在裸燕麦根、茎和叶中未检出硒元素和CO^2-₃。盐碱胁迫下,外源H₂S对裸燕麦效应：(1)对根、茎和叶中HCO^-₃、Cl^-和SO^2-₄含量无显著影响,可显著缓解盐碱胁迫下裸燕麦根系和地上部干重的下降。（2）显著降低茎、叶中Na含量,对根中Na含量和叶片 SOS1基因表达无显著影响,显著提高叶片 NHX1基因表达量。(3) 提高根、茎和叶中Ca、Mg、P的含量,抑制K的吸收和运输;促进S的吸收,但抑制S的转运;降低根、茎中Si含量,通过提高Si从茎向叶转运而提高叶中Si含量。(4) 显著提高根、茎和叶中Co含量;促进Ni的转运及Fe从根向茎、Zn从茎向叶的转运,提高根中Mn、Zn和茎中Fe及叶片Ni、Zn含量;抑制B、Mn、Cu、Zn从根向茎和Mo从茎向叶的转运,降低茎中B、Mn、Cu、Ni、Zn和叶片中B、Mn、Cu、Mo含量。(5) 显著提高根中Li、Sr、Ag和茎中Li、Sr及叶片Sr、Ag含量,降低根中Ba和叶片Rb含量。(6) 对根、茎和叶中重金属元素Cd、Hg、Pb、Cr和As含量的影响存在差异,对根、茎和叶中Al含量的升高有显著缓解作用。由此可见,外源H₂S参与盐碱胁迫下裸燕麦矿质元素吸收、转运和分配的调控,能够增强裸燕麦的耐盐碱性。     

烯啶虫胺对椰心叶甲的生物活性

为探索椰心叶甲防治的新方法,室内测定了烯啶虫胺对椰心叶甲的胃毒、杀卵和触杀作用。结果表明：烯啶虫胺对椰心叶甲5龄幼虫具有很强的胃毒作用,24和48 h的LC50值分别为1.25和0.52 mg/L;对椰心叶甲也有显著的杀卵作用,在供试浓度为0.5～5 mg/L时,对椰心叶甲卵孵化率和幼虫存活率均在50%以下;烯啶虫胺对椰心叶甲5龄幼虫也有一定的触杀作用,其24和48 h的LC50值分别为0.188和0.178 mg/L。烯啶虫胺具有防治椰心叶甲的潜力。     

31种热带植物乙醇提取物对朱砂叶螨的生物活性研究

室内测定31种植物乙醇提取物对朱砂叶螨的触杀和驱避作用.结果表明,大山芝麻、蜂巢草、仔榄树和许树乙醇提取物对朱砂叶螨具有明显的触杀作用,24h后平均校正死亡率达80％以上,其中大山芝麻的触杀效果最好,高达96.35％;23种植物提取物对朱砂叶螨产卵驱避作用显著,平均驱避率达90％以上;牛筋果、云南野桐、多花瓜腹木、黄椿木姜、酒饼簕和毛瓣鸡血藤提取物对成螨驱避作用明显且较为稳定,48 h的平均驱避率达91％以上.     

种植密度对夏玉米果穗叶生理功能衰退的影响

以郑单958为供试品种,在大田条件下研究不同种植密度对夏玉米果穗叶生理功能衰退特性的影响。结果表明：果穗叶叶绿素a+b含量、原初光化学效率(F_v/F_m)、光系统Ⅱ(PSⅡ)潜在活性(F_v/F_o)、可溶性蛋白、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性均随果穗叶功能期的推进呈下降趋势,且随密度的增大下降趋势明显,吐丝后39d下降最显著;果穗叶叶绿素a/b、丙二醛(MDA)含量呈逐渐上升趋势。随着种植密度的增大,果穗叶光能转化和自身保护酶系活性下降,光合生产能力减弱,造成果穗叶生理功能早衰,缩短了叶片功能期。     

农杆菌介导法将抗草甘膦基因转入玉米自交系

利用农杆菌介导法将抗草甘膦基因(ssu-G₂-aroA)转入优良玉米自交系R18-599和齐319,侵染后的愈伤组织转至潮霉素浓度为10 mg/L的筛选培养基上,继代筛选3轮,每轮3周;得到的抗性愈伤组织在含有潮霉素浓度为3 mg/L的分化培养基上进行分化,R18-599获得30株再生植株,齐319获得18株再生植株。经PCR鉴定后共得到7株转化抗性植株(4株R18-599、3株齐319)。经PCR-Southern及RT-PCR检测结果表明,ssu-G₂-aroA基因已稳定整合到了玉米基因组中,并在RNA水平上得到表达。     

Toxic effects of neem-based insecticides on Pieris brassicae (Linn.)

Four neem-based insecticides, Neemix^® (0.25% EC @ 20 mg azadirachtin/liter), Ecozin^® (3% EC @ 20 mg azadirachtin/liter), Agroneem^® (0.15% EC @ 4.8 mg azadirachtin/liter) and Neem oil (0.25% EC azadirachtin @ 20 mg azadirachtin/liter) and a non-commercial neem leaf powder, were evaluated for oviposition deterrence, antifeedant effect to larvae and toxicity to eggs and larvae of Pieris brassicae (Linn.) on cabbage leaves in the laboratory. The concentrations tested were with in the ranges of recommended field rates. Oviposition deterrence in no-choice, two-choice and six-choice assays, was observed for all the treatments. They exhibited significant (P < 0.01) oviposition deterrence on P. brassicae when compared with a non-treated control. Cabbage leaves treated with the neem-based insecticides were used as an egg-laying substrate. Numbers of eggs oviposited by P. brassicae adults on treated cabbage leaves were significantly lower then those treated with water, but no significant differences were detected among the neem insecticides. They also deterred feeding by Pieris larvae and exhibited significant antifeedant effects. Larvae of P. brassicae on treated leaves stopped feeding and dropped from the leaf, resulting in no or minimal damage. Direct contact with neem-based insecticides decreased the survival of eggs. Survival of larvae fed for 9 days on leaves treated with neem-based insecticides was reduced to 51%, 49%, 48%, 24% and 18% in the Neem oil, Neemix, Agroneem, Ecozin and neem leaf powder treatments, respectively. Therefore, it can be concluded from the present investigations that neem-based insecticides had oviposition deterrence, antifeedant and toxic effect to P. brassicae.     

硅对NaCl胁迫下玉米幼苗生理特性的影响

采用水培法研究盐胁迫下不同浓度硅对玉米幼苗生长、叶绿素含量、保护酶活性等生理特性的影响。结果表明,适量的硅(1mmol/L)能有效促进玉米生长,抑制叶绿素含量降低,降低细胞膜透性,提高玉米叶片和根系中的SOD、CAT和POD活性。叶片中SOD、CAT、POD活性均以Na2SiO3浓度为1mmol/L时活性最强;根系中三种酶活性以Na2SiO3浓度为2mmol/L时最强,表明硅对叶片和根系中的酶活性调控并非完全同步,也可能是硅在叶片和根系中作用途径不同所致。     

甘肃武威市凉州玉米产区截形叶螨对3种杀螨剂的敏感性测定

截形叶螨(Tetranychus truncatus Ehara)是我国玉米生产上的一种重要的害螨。目前对截形叶螨的防治主要依赖化学农药。本研究通过室内浸液法测定截形叶螨成螨、若螨对3种不同作用机制的杀螨剂乙唑螨腈、联苯肼酯和螺螨酯的敏感性。结果表明,乙唑螨腈的毒力最强,对雌成螨和若螨24 h的LC50分别为0.033 mg/L、0.070 mg/L;联苯肼酯的毒力最低,对雌成螨和若螨24 h的LC50分别为0.685 mg/L、0.210 mg/L。3种杀螨剂对产卵量的影响均显著。乙唑螨腈可作为田间防治截形叶螨的最佳备选药剂。     

Comparative effects of salt and alkali stresses on organic acid accumulation and ionic balance of seabuckthorn (Hippophae rhamnoides L.)

Seabuckthorn (Hippophae rhamnoides L.) is uniquely capable of growing well under various extreme environmental conditions, such as water deficit, salt stress, low temperature, and high altitude. It is of economic value and its berries are used in cosmetics and pharmaceutical products. In this study, we compared the effects of salt stresses (9:1 molar ratio of NaCl to Na₂SO₄, pH 6.48–6.65) and alkali stresses (9:1 molar ratio of NaHCO₃ to Na₂CO₃, pH 8.70–8.88) on the levels of inorganic ions and organic acids in H. rhamnoides L. to elucidate the physiological mechanism by which it tolerates salt or alkali stress (high pH). The results showed that, in leaves and stems under alkali stress, the Na⁺ content increased to a much greater extent than under salt stress. Neither salt nor alkali stress decreased the K⁺ content in leaves and stems; however, in roots, the K⁺ content decreased sharply with increasing alkali stress, whereas it remained relatively unchanged with increasing salt stress. This revealed a specific mechanism of absorption or transport for Na⁺ and K⁺ that was affected strongly by alkali stress. The results indicated that accumulation of organic acid (OA) was a central adaptive mechanism by which H. rhamnoides maintained intracellular ionic balance under alkali stress. OA may play different roles in different organs during adaptation to alkali stress, and its percentage contribution to total negative charge was higher in leaf than in stem. H. rhamnoides accumulated mainly malate, oxalate, and citrate in leaves and stems; however, in roots, less malate and citrate was accumulated, and acetate accumulation was enhanced significantly, which indicated that roots and shoots use different mechanisms to modulate OA metabolism.     

Antioxidant activity and phenolic composition of the medicinal and edible halophyte Mesembryanthemum edule L.

Mesembryanthemum edule L. (sourfig, Aizoaceae) has long been used as food and in traditional medicine. This study was intended to characterize the antioxidant properties and the phenolic compounds of M. edule leaf, stem and root. The approach consisted to evaluate these organs for their antioxidant activities through several in vitro tests, to determine tissue contents in total phenolics, flavonoids and proanthocyanidins and to establish the phenolic composition through RP-HPLC analysis. All studied organs showed a high antioxidant activity as compared to positive control BHT, with maximal efficiency for stems followed by leaves and roots. The highest polyphenolic levels were found in stems and leaves (86.5 and 68.7 mg GAE g⁻¹ DW, respectively), suggesting that their strong antioxidant activity could be attributed to these phytochemicals. The HPLC analysis revealed that the main phenolic compounds were quercitrin and avicularin (1.4 and 1.15 mg g⁻¹ DW, respectively) in the leaves, while catechin and procyanidin B2 (1.66 and 1.54 mg g⁻¹ DW, respectively) were the most abundant phenolics in the stems. Overall, the strong antioxidant activity and richness of M. edule aerial tissues suggest that it could be advantageously used as a functional or nutraceutical food, to prevent or moderate oxidative stress-related diseases.     

Antifouling Activity of Synthetic Alkylpyridinium Polymers Using the Barnacle Model

Polymeric alkylpyridinium salts (poly-APS) isolated from the Mediterranean marine sponge, Haliclona (Rhizoniera) sarai, effectively inhibit barnacle larva settlement and natural marine biofilm formation through a non-toxic and reversible mechanism. Potential use of poly-APS-like compounds as antifouling agents led to the chemical synthesis of monomeric and oligomeric 3-alkylpyridinium analogues. However, these are less efficient in settlement assays and have greater toxicity than the natural polymers. Recently, a new chemical synthesis method enabled the production of poly-APS analogues with antibacterial, antifungal and anti-acetylcholinesterase activities. The present study examines the antifouling properties and toxicity of six of these synthetic poly-APS using the barnacle (Amphibalanus amphitrite) as a model (cyprids and II stage nauplii larvae) in settlement, acute and sub-acute toxicity assays. Two compounds, APS8 and APS12-3, show antifouling effects very similar to natural poly-APS, with an anti-settlement effective concentration that inhibits 50% of the cyprid population settlement (EC₅₀) after 24 h of 0.32 mg/L and 0.89 mg/L, respectively. The toxicity of APS8 is negligible, while APS12-3 is three-fold more toxic (24-h LC₅₀: nauplii, 11.60 mg/L; cyprids, 61.13 mg/L) than natural poly-APS. This toxicity of APS12-3 towards nauplii is, however, 60-fold and 1200-fold lower than that of the common co-biocides, Zn- and Cu-pyrithione, respectively. Additionally, exposure to APS12-3 for 24 and 48 h inhibits the naupliar swimming ability with respective IC₅₀ of 4.83 and 1.86 mg/L.     

乙烯利对花生农艺和生理性状的影响

以六种浓度的乙烯利对初花期花生进行叶面喷施,定期观测其主要农艺、生理生化及产量指标。结果表明,喷施适宜浓度的乙烯利可抑制地上部分的生长,提高叶片和植株物质积累量;100 mg/L和150 mg/L乙烯利处理能优化花生植株的生理生化特性,表现为显著提高花生叶片的蛋白质含量和叶绿素含量及SOD和POD活性,增强花生叶片的光合速率和蒸腾速率,增强了主根活力,降低花生叶片丙二醛和可溶性糖含量;200 mg/L乙烯利处理能提高植株的单株结荚数、饱果率和产量,但百果重和百仁重有所下降。     

几种野生稻抽提物对斜纹夜蛾幼虫的拒食作用

用甲醇对6种野生稻E6-1, E6-3/6-4(大颖野生稻的不同生态型),E7-4(颗粒野生稻), E9-10、E9-20(阔叶野生稻的不同生态型),E13-13（小粒野生稻）,E15-13（药用野生稻）和E16-3（斑点野生稻）进行了索氏提取,提取率分别为19.62%,15.60%,18.90%,8.50%,16.27%, 24.86%,10.04%和13.32%。通过测定这6种野生稻抽提物对3龄斜纹夜蛾幼虫的选择性拒食活性和非选择性拒食活性,筛选出大颖野生稻抽提物E6-1对斜纹夜蛾有较强的拒食作用。用E6-1对叶碟处理后,在1%的浓度下,24 h和48 h测得其对3龄斜纹夜蛾选择性拒食率均为100%,而非选择性拒食率分别为40.95%和47.27%;毒力测定表明2龄斜纹夜蛾幼虫24 h和48 h后的拒食中浓度([i]AFC[/i][sub]50[/sub]）分别为120 mg/mL和50 mg/mL。