The newest leafminer pest in Israel,Liriomyza huidobrensis

The pea leafminer,Liriomyza huidobrensis (Blanchard), recently introduced into Israel, has proven to be extremely proliferous and difficult to control. It is a much more serious pest of vegetable and flower crops than the previously introducedLiriomyza trifolii (Burgess). Photosynthesis is reduced and cosmetic damage is incurred when adult flies stipple plant leaves with feeding punctures and larvae mine the leaves. This paper will review briefly the history, biology and potential control measures of the pea leafminer.     

Evaluation of cinnamamide as an avian repellent: Determination of a dose—response curve

The dose-response curve was quantified for the avian repellency of cinnamamide, a derivative of the plant secondary compound cinnamic acid, using a three-day, ‘short-term no-choice’ test. This test was designed to resemble more closely the availability of alternative food in the birds' natural environment than in previous no-choice studies. Cinnamamide reduced food consumption by feral pigeons (Columba livia Gmelin) at concentrations as low as 6.17 μmole g^?1 food (0.09% w/w) and this reduction increased with concentration. An R₅₀ index, the concentration at which food consumption was reduced by 50% was interpolated from the dose-response curve as 18.4 (±0.38) μmole g^?1 food 10.26% w/w). This index can now be matched with those of related compounds in future structure-activity studies. The birds' response to cinnamamide changed over the three-day trial with respect to concentration. Repellency declined at concentrations < R₅₀ and increased at concentrations > R₅₀. This suggests that pigeons become habituated to cinnamamide at low concentrations but at high concentrations they may develop a conditioned aversion. This study provides quantitative confirmation of previous laboratory and field demonstrations of cinnamamide's effectiveness as a non-lethal chemical repellent suitable for reducing avian pest damage.     

组蛋白在基因调控中的作用

组蛋白曾一度只被看成是细胞核ＤＮＡ结构的组成成分，是转录的通用抑制分子。最近研究表明，这类蛋白质是基因调节过程中活跃的参与者，不仅抑制又能促进许多基因的活化。     

Impacts of atmospheric CO<Subscript>2</Subscript> concentrations and soil water on the population dynamics,fecundity and development of the bird cherry-oat aphid<Emphasis Type="Italic">Rhopalosiphum padi</Emphasis>

The impacts of elevated CO₂ and soil water on the population dynamics, adult fecundity and nymphal period of the bird cherry-oat aphidRhopalsiphum padi (Linnaeus) were evaluated in three experiments: (i)Combined effects of CO ₂ and soil water on aphid populations. Spring wheat was grown in pots at three CO₂ concentrations (350, 550 and 700 ppm) and three soil water levels (40%, 60% and 80% of field water capacity, FWC) in field open-top chambers (OTC) and infested with the bird cherry-oat aphid. Aphid population dynamics were recorded throughout the growing season; at the same time, adult fecundity and duration of the nymphal period were recorded. Chemical composition of spring wheat leaves was also analyzed. (ii)Indirect effects of CO ₂ concentrations and soil water on aphid adult fecundity and nymphal period. The experiment was conducted with the leaf discs method in the laboratory. Aphids were reared on leaf discs excised from the treated wheat in OTC with different CO₂ and soil water levels. (iii)Direct effects of CO ₂ concentrations on aphid adult fecundity and nymphal period. Aphids were reared on leaf discs excised from the wheat grown under natural conditions. The experiment was conducted with the leaf disc method in OTC with the three CO₂ concentrations. It was found that the direct effect of CO₂ concentration on aphid population parameters was minor. CO₂ and soil water affected aphid population indirectly through their effects on wheat characteristics. The aphid population under 550 ppm CO₂ was far larger than the one under 350 ppm CO₂, whereas the population under 700 ppm CO₂ was slightly higher than that under 550 ppm CO₂. The largest aphid population was obtained with the 60% soil water treatment, regardless of CO₂ treatment. The effects of CO₂ concentration on aphid population were, however, not significantly correlated with soil water level. Adult fecundity increased with CO₂ concentration, the highest fecundity being achieved under 60% FWC treatments. The nymphal period was not affected by CO₂ concentration. The shortest period occurred under 60% FWC. Atmospheric CO₂ and soil water had significant effects on the chemical composition of the wheat leaves. Aphid population size was positively correlated with leaf water content, concentrations of soluble proteins, soluble carbohydrates and starch, and negatively correlated with DIMBOA and tannins concentrations. http://www.phytoparasitica.org posting Oct. 20, 2003.     

加速结构调整是大兴安岭可持续发展的必然

文章指出以“天保工程”为契机 ,以林业的持续发展为目的 ,调整大兴安岭林业生产结构 ,发挥其多功能互助的整体效益     

抗噻枯唑和抗叶枯净的水稻白叶枯病菌株的适应度比较

将水稻白叶枯病噻枯唑抗性菌和叶枯净抗性菌的适应度特性进行了比较。当Ｓａ＾ｒ和Ｐ＾ｒ与敏感菌（Ｓ）的等量混合物在植株上繁殖时,Ｓａ＾ｒ和Ｐ＾ｒ竞争不过Ｓ,但Ｐ＾ｒ竞争能力较Ｓａ＾ｒ强。Ｓａ＾ｒ和Ｐ＾ｒ的致病力与Ｓ的无明显差异。但在离体保存时Ｓａ＾ｒ和Ｐ＾ｒ易于丧失致病力。这种致病力的丧失是由于被保原群体中低致病力的敏感菌比例上升所致,进一步说明Ｓａ＾ｒ和Ｐ＾ｒ的适应度不及Ｓ。结果表明,白叶枯病市民经     

犬尿结石的化学成分分析研究

应用物理学特征观察、化学定性分析、X射线衍射分析等方法,分析了临床收集的1份犬肾结石样品、2份犬膀胱结石样品的化学成分,并根据结石的形成原因、机理探讨其防治方法。结果表明:肾结石样品为混合型结石,主要成分为水合磷酸氢镁、水合磷酸铁及水合磷酸钙,另外还可能含有少量水合硫酸钙;2份膀胱结石样品主要成分均为六水磷酸铵镁。对尿结石的成分分析,有助于了解结石形成机制,为尿结石的防治奠定一定基础。     

苏丹红和饲料着色剂的区别

本文主要从苏丹红和饲料着色剂的化学结构、作用机理及毒性等方面说明饲料着色剂与苏丹红的天壤之别。     

中华蜜蜂工蜂碱性磷酸酶功能基团的研究

在一定条件下，分别采用二硫代二硝基苯甲酸（DTNB）、N-溴代琥珀酰亚胺（NBS）、苯甲基磺酰氟（PMSF）、溴乙酸（BrAc）、乙酰丙酮、巯基乙醇（ME）等化学修饰剂选择修饰中华蜜蜂碱性磷酸酶多种氨基酸残基，并测定其酶活力变化。结果表明，DTNB、PMSF的修饰不表现对酶的抑制作用，而NBS、BrAc、ME能显著抑制酶的活力，乙酰丙酮也能抑制酶的活力，但是不太明显。因此认为Trp、His是中华蜜蜂工蜂碱性磷酸酶的必需功能基团，部分二硫键对保护酶的催化功能也是必需的。     

中药凤尾草的研究进展

凤尾草是一种传统的药用植物,具有很高的药用价值,应用前景广阔。本文综述了凤尾草的鉴定、临床应用、药理作用和化学成分的研究概况,为中药凤尾草资源开发与合理利用提供依据。