取食不同寄主植物的二个甜菜夜蛾品系对药剂的敏感性

探讨取食不同寄主植物的2种甜菜夜蛾Spodoptera exigua(Hübner)品系对几种常用药剂的敏感性变化情况。试验结果表明,寄主植物对甜菜夜蛾的生长发育和杀虫剂的敏感性有显著影响,取食不同寄主植物以后,甜菜夜蛾2个品系对溴氰菊酯、毒死蜱、溴虫腈、虫酰肼的敏感性均有不同程度的变化,取食不同寄主植物的甜菜夜蛾蛹黑突变品系较甜菜夜蛾正常品系的抗性均要高,2个品系对溴氰菊酯的敏感性变化均较大,最大LD50之比分别达到13.36、12.30倍,2个品系都对虫酰肼的敏感性变化不明显,最大LD50之比分别达到2.54、2.23倍。     

甜菜夜蛾核型多角体病毒中国分离株的分离鉴定及毒力测定

本文对分离自中国的甜菜夜蛾病毒进行提纯、鉴定.生物测定的结果表明其对二龄、三龄甜菜夜蛾的LC50分别为6.6× 104,2.6×105PIB/mL.     

甜菜夜蛾cDNA文库的构建

以甜菜夜蛾Spodoptera exigua(Hübner)幼虫为材料建立了cDNA表达文库,经检测文库的初始滴度为1.1×105pfu/mL,重组率为97%,扩增后文库的滴度为5.4×107pfu/mL。用设计的2对引物筛选该文库,得到468 bp的1个片段,分析后证实是几丁质合成酶基因I保守区域的1个片段。该cDNA文库为进一步筛选甜菜夜蛾功能基因奠定了基础。     

SeMNPV两个分离株的生物活性比较及病毒杀虫剂的应用

本文对甜菜夜蛾核型多角体病毒的两个分离株(SeMNPV-M,SeMNPV-Z)的生物活性进行了比较,并对甜菜夜蛾核多角体病毒杀虫悬浮剂的田间应用效果进行了评估.病毒生物测定结果显示,SeNPV-M和SeNPV-Z感染三龄幼虫的半致死剂量(LD50)分别为195.8 PIBs/克饲料和242.4 PIBs/克饲料.使用6000PIB/克饲料的病毒剂量感染三龄幼虫,其半致死时间(LT50)分别为3.50d和3.68d.甜菜夜蛾病毒杀虫悬浮剂已在工厂生产,田问实验结果表明,甜菜夜蛾病毒杀虫悬浮剂可有效控制目标害虫的危害.     

甜菜夜蛾体内代谢耐受性对转Bt基因棉响应的时间动态

在室内用转Bt基因棉和亲本常规棉饲养甜菜夜蛾（Spodoptera exigua Hübner）幼虫,测定了不同取食时间后甜菜夜蛾4龄幼虫体内营养物质含量和消化酶、保护酶、解毒酶活力的变化．结果表明,分别取食Bt棉和常规棉,甜菜夜蛾幼虫体内的营养物质含量和消化酶、保护酶、解毒酶活力差异显著．与取食常规棉相应时间的个体相比,取食Bt棉1,6,24h后,幼虫体内的游离脂肪酸和葡萄糖含量显著提高;取食Bt棉1,4,6,24h后,幼虫体内胰蛋白酶和总超氧化物歧化酶的活力显著增高,脂肪酶、羧酸酯酶和乙酰胆碱酯酶活力则显著降低．取食相同品种棉花,幼虫体内营养物质含量和消化酶、保护酶、解毒酶活力受甜菜夜蛾危害时间的显著影响．取食Bt棉24h的幼虫,其体内游离脂肪酸和总氨基酸含量显著低于取食1h的个体;脂肪酶和胰蛋白酶活力显著低于取食1和4h的个体,但羧酸酯酶和乙酰胆碱酯酶酶活力显著高于取食1,4,6h的个体．棉花品种和甜菜夜蛾为害时间的交互作用可显著影响甜菜夜蛾体内脂肪酶、胰蛋白酶、乙酰胆碱酯酶和总超氧化物歧化酶的活力．通过测定甜菜夜蛾体内保护酶和解毒酶活力对Bt棉响应的时间动态,对于评价植食性昆虫在毒素蛋白持续选择压力下的生理反应和抗性变化具有重要参考意义．     

取食不同食物的甜菜夜蛾幼虫感染核型多角体病毒后中肠组织的变化

【目的】观察取食人工饲料和3种寄主植物的甜菜夜蛾Spodoptera exigua 3龄幼虫感染核型多角体病毒后,其中肠组织的病理变化。【方法】核型多角体病毒感染甜菜夜蛾后,剖取围食膜观察在不同时间点围食膜的变化,以及采用组织切片法探究取食人工饲料和不同寄主植物的甜菜夜蛾感染病毒前后其中肠组织的病理变化。【结果】幼虫感毒后的围食膜首先由无色透明、具有弹性的圆桶状结构,变成乳白色、弹性降低的单片状结构,随着感毒后时间的推移,围食膜破坏严重,变成无弹性的碎片状。取食不同寄主植物和人工饲料的甜菜夜蛾在未感染病毒时其中肠组织都没有明显的变化,而感染病毒后甜菜夜蛾中肠组织围食膜被破坏或消失;中肠柱状细胞伸长、变形,细胞间隙变大,排列混乱,细胞脱落,肠壁变厚。此外,核型多角体病毒对取食人工饲料和不同寄主植物的甜菜夜蛾中肠组织的影响也存在差异,对取食人工饲料和黄豆的影响类似且最大、甘蓝次之,蕹菜最小。【结论】核型多角体病毒对甜菜夜蛾中肠组织具有显著的影响,且取食不同寄主植物时其影响存在明显差异。     

辛硫磷与Cry1Ca的协同增效及对甜菜夜蛾SeALP mRNA转录水平的影响

本试验旨在明确辛硫磷(Phoxim)与Bt蛋白Cry1Ca防治甜菜夜蛾Spodoptera exigua的协同增效作用,及对甜菜夜蛾碱性磷酸酯酶(SeALP) mRNA转录水平的影响。结果表明,与空白对照处理相比,喂食辛硫磷(LC30)与Cry1Ca (LC30)混合物的甜菜夜蛾幼虫历期、蛹历期延长,并且在处理后3、5、7 d的实际死亡率分别为52. 73%、93. 13%、95. 87%;但仅喂食辛硫磷(LC30)死亡率分别为30. 67%、44. 67%、45%,仅喂食Cry1Ca (LC30)死亡率分别为0. 00%、17. 73%、17. 73%,因此辛硫磷与Cry1Ca对防治甜菜夜蛾的协同增效作用显著。qPCR分析SeALP mRNA转录水平的变化,发现甜菜夜蛾SeALP1的转录水平随取食时间推移呈先升高后降低的趋势,SeALP2-SeALP5的转录呈先降低后升高的趋势。综上所述,辛硫磷与Bt蛋白混配可提高对甜菜夜蛾的防治效果,研究结果有助于阐明甜菜夜蛾抗性产生原因及机理,并为农药减量增效技术的研发提供科学依据。     

植物次生代谢物对甜菜夜蛾生长发育及解毒酶的影响

【目的】明确植物次生代谢物对甜菜夜蛾Spodoptera exigua生长发育及解毒酶的影响,探索利用植物次生物质防控甜菜夜蛾的潜在途径。【方法】本研究选用3种含量（0.01%、0.1%和1.0%）的槲皮素、山奈酚和香豆素,分别与人工饲料混合均匀后饲养甜菜夜蛾3龄初幼虫,观察植物次生代谢物对幼虫生长发育的影响;并测定幼虫取食添加0.1%的槲皮素、山奈酚和香豆素的人工饲料24、48和72 h后,幼虫羧酸酯酶（Caboxylesterase,CarE）、谷胱甘肽-S-转移酶（Glutathione-S-transferase,GSTs）和P450解毒酶活性。【结果】添加不同次生物质的人工饲料显著影响甜菜夜蛾幼虫生长和解毒酶活性。与对照组相比,3种次生代谢物均显著提高了幼虫死亡率。幼虫取食添加1%槲皮素的人工饲料后,蛹重显著降低,发育历期明显延长。而取食添加0.1%山奈酚的人工饲料后,可诱导幼虫CarE活性显著增强,0.1%槲皮素和0.1%香豆素对幼虫CarE活性均有显著抑制作用。添加槲皮素对幼虫GSTs活性无显著性影响,添加0.1%山奈酚和0.1%香豆素可诱导幼虫GSTs活性显著升高。0.1%槲皮素和0.1%香豆素可促进幼虫P450活性增强但未达到显著水平,但0.1%山奈酚处理48h后,幼虫P450活性显著降低。【结论】植物次生代谢物种类与含量对甜菜夜蛾生长发育及解毒酶活性存在不同程度的影响。     

转tcdA1B1杀虫基因的阴沟肠杆菌对4种农业害虫的杀虫活性与毒力

tcdA1B1为昆虫病原细菌一发光杆菌Photorhabdus luminescens的杀虫毒素基因。本文测定了转tcdA1B1基因的阴沟肠杆菌对甜菜夜蛾Spodoptera exigua、斜纹夜蛾Spodoptera litura、黄曲条跳甲Phyllotreta striolata和东亚飞蝗Locusta migratoria manilensis4种重要农业害虫的杀虫活性与毒力。在室内条件下,浓度为5．0×108cfu／mL的工程菌悬浮液,采用叶片浸渍法饲喂甜菜夜蛾2龄幼虫、斜纹夜蛾2龄幼虫、黄曲条跳甲成虫、东亚飞蝗2龄若虫,在11d、11d、15d、19d后的致死率分别为80．05％、81．83％、72．31％、39．74％;LT50分别为8．64d,8．38d、11．04d、28．22d。     

SeMNPV两个分离株的生物活性比较及病毒杀虫剂的应用

本文对甜菜夜蛾核型多角体病毒的两个分离株(SeMNPV-M,SeMNPV-Z)的生物活性进行了比较,并对甜 菜夜蛾核多角体病毒杀虫悬浮剂的田间应用效果进行了评估。病毒生物测定结果显示,SeNPV-M和SeNPV-Z 感染三龄幼虫的半致死剂量(LD50)分别为195．8 PIBs／克饲料和242．4 PIBs／克饲料。使用6000PIB／克饲料的病 毒剂量感染三龄幼虫,其半致死时间(LT50)分别为3．50d和3．68d。甜菜夜蛾病毒杀虫悬浮剂已在工厂生产,田间 实验结果表明,甜菜夜蛾病毒杀虫悬浮剂可有效控制目标害虫的危害。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Chemical constituents from the fruits of Rhus typhina L. and their chemotaxonomic significance

This work describes the isolation and characterization of twenty-nine compounds from the fruits of Rhus typhina L., including eleven flavonoids (1–11), eleven phenols (12–22), two pentacyclic triterpenes (23–24), two organic acids (25–26), one lumichrome (27), one courmarin (28) and one pyrimidine (29) on the basis of their spectroscopic data. Compounds apigenin (1), daidzein (4), orobol (5), 3′, 5, 5′, 7-tetrahydroxyflavanone (6), naringenin (7), butein (8), (-)-catechin (9), quercetin-3-O-α-L-(3″-O-galloyl)-rhamnoside (11), 2-hydroxybenzoic acid (13), 4-hydroxybenzaldehyde (14), vanillin (15), methyl 3,4-dihydroxybenzoate (16), 3,5-dihydroxybenzamide (18), tyrosol (19), caffeic acid (20), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (21), phlorizin (22), friedelin (23), oleanolic acid (24), 4,4-dimethyl-heptanedioic acid (25), anthranilic acid (26), lumichrome (27), scoparone (28) and uracil (29) have not been recorded before in this plant. This is the first report on the occurrence of compounds 4–7, 9, 11, 13–14, 16, 18–21, 25–29 from the genus Rhus. Moreover, the chemotaxonomic significance of these isolated compounds was also summarized.