Variability in response to toosendanin in a laboratory colony of<Emphasis Type="Italic">Trichoplusia ni</Emphasis>

Laboratory rearing of insects for scientific research ensures a constant supply of insects. However, laboratory colonies may diverge genetically and/or phenotypically from wild populations due to selection pressures in their artificial environment. This study examined how variation in a colony ofTrichoplusia ni influenced reproducibility over time of bioassays of toosendanin (a limonoid extracted from the bark ofMelia azedarach). In four of five experiments insect growth was reduced significantly (P=0.05) by the presence of toosendanin in the diet. The fifth experiment showed the same trend, but the effect was not significant. Mean larval mass of both control and treated insects also varied greatly among experiments. The considerable variability observed in this population highlights the importance of replicating experiments in time, and not just space, to confirm reproducibility of treatment effects. http://www.phytoparasitica.org posting Jan. 23, 2007.     

一株惊纹地老虎幼虫颗粒体病毒的研究

1978年春,在新疆博湖从惊纹地老虎Agrotis exclamationis(Linné)(鳞翅目:夜蛾科)幼虫中发现一株病毒“Ae—02”,病毒颗粒体为卵形或卵圆形,大小为374～780×312～450nm,平均为578×412nm;病毒粒子杆状,两端钝圆,不弯曲或稍弯曲,大小为350～450×40～65nm,平均为395×50nm。该病毒对惊纹地老虎和黄地老虎A.segetum(Schiff.)幼虫致病力强。在日平均温度为24.2℃时,对1日龄惊纹地老虎幼虫感病19天后死亡率达96～100%;25天后10日龄幼虫死亡率达84～92%;对15日龄幼虫死亡率为73.96～80.96%。惊纹地老虎病毒“Ae—02”毒株,属杆状病毒科Baculoviridae,杆状病毒属Baculovirus,“B”亚组,定名为惊纹地老虎颗粒体病毒Agrotis excula-mationis granulosis virus,俗名鸣夜蛾颗粒体病毒,拉丁学名为Baculovirusexclamationis“B”,简称AeGV。     

不同青贮玉米大喇叭口期和成熟期耐盐碱性综合评价

以25个不同青贮玉米品种为试验材料,在宁夏银川北部盐碱地,通过测定不同品种大喇叭口期和成熟期的表型性状和光合气体交换参数进行耐盐碱性鉴定,并利用主成分分析和模糊隶属函数法对不同青贮玉米的耐盐碱强弱进行综合评价。结果表明：各青贮玉米品种处于不同生育期时对盐碱的敏感程度不同（发育阶段性）,同一时期不同品种之间耐盐碱性也存在着差异（品种特异性）。根据综合评价值（D值）大小,将耐盐碱性分为三级：D值大于0.6为强耐盐碱性材料;D值在0.2~0.6之间为中耐盐碱性材料;D值低于0.2为对盐碱敏感的材料。其中,在大喇叭口期时具有强耐盐碱性的材料有：科多8号、桂青贮1号和133-2/1528,D值分别为0.770、0.705和0.614;在成熟期时具有强耐盐碱性的材料有：H14/A18和桂青贮1号,D值分别为0.761和0.728;而表现为敏盐性的材料为H14/1528,D值在大喇叭口期和成熟期时分别为0.140和0.155;其余品种均属于中度耐盐碱材料,D值处于0.2~0.6之间。     

拮抗细菌HD-86发酵液稳定性及对相似穿孔线虫的活性

利用PCR特异性引物检测了一株对相似穿孔线虫具有高拮抗活性的Burkholderia cepacia菌株HD-86的毒性,结果未检测到该菌株中与人体致病相关的洋葱伯克霍尔德氏菌致病因子(BCESM)毒力基因,从而验证了其对人类和环境的安全性.菌株HD-86发酵上清液对相似穿孔线虫拮抗活性稳定性的研究结果表明,经80℃高温处理60 min后其拮抗活性仍然极高,在pH为8～10的范围内随着碱性增强其拮抗性效果越好,紫外线处理对其拮抗活性没有影响.     

不同杀菌剂对小麦纹枯病和赤霉病的防治效果

为明确不同杀菌剂对小麦纹枯病、赤霉病的防治效果,在大田条件下以‘开麦21’为试验材料研究了12种杀菌剂对小麦纹枯病、11种杀菌剂对赤霉病的防治效果及对小麦产量的影响。结果表明:30%己唑醇悬浮剂76.5g/hm2、75%肟菌·戊唑醇水分散粒剂168.75g/hm2处理对小麦纹枯病的防效较好,拔节期病指防效(乳熟期枯白穗防效)分别为62.77%(56.21%)和60.58%(53.45%),小麦产量较对照分别增加27.65%和21.30%;48%氰烯·戊唑醇悬浮剂432g/hm2、25%氰烯菌酯悬浮剂750g/hm2处理对小麦赤霉病的防效较好,病指防效(病穗防效)分别为70.78%(56.57%)和68.84%(46.86%),小麦产量较对照分别增加25.44%和24.40%。综合分析,以上药剂可做田间大面积推广应用。     

Multi-scale study of bird species distribution and of their response to vegetation change: a Mediterranean example

Land use changes operate at different scales. They trigger a cascade of effects that simultaneously modify the composition or structure of the landscape and of the local vegetation. Mobil animals, and birds in particular, can respond quickly to such multi-scalar changes. We took advantage of a long term study on the response of songbirds to land-use changes on four Mediterranean islands in Corsica and Sardinia to explore the benefits of a multi-scale analysis of the relationships between songbird distribution, vegetation structure and landscape dynamics. Field data and aerial photographs were used to describe the vegetation at three different scales. Birds were censused by point counts. We used statistical variance decomposition to study how bird distribution and vegetation at various scales were linked. We analysed multi-scale vegetation changes (floristic composition, plot vegetation type, and landscape structure) and their consequences on bird distribution with multivariate and non-parametrical tests. The distribution of most species was linked to at least two spatial scales. The weight of a given scale was consistent with life-history traits for species whose biology was well-known. In the examples studied, vegetation composition, vegetation type and landscape changes that resulted from land abandonment negatively affected birds depending on open or heterogeneous areas. Our results emphasize that multi-scale analyses can greatly enhance our understanding of bird distribution and of their changes. Management of these populations should take into account measures at various spatial scales depending on the sensitivity of the species.     

小菜蛾γ- 氨基丁酸受体基因片段的克隆、表达及特征分析

 利用反转录多聚酶链式反应(RT-PCR) 对小菜蛾( Plutella xylostella ) 的γ - 氨基丁酸a(GABAa) 受体基因cDNA片段进行了克隆和序列分析。通过简并性上游引物和下游引物扩增出小菜蛾GABAa受体基因248 bp的cDNA片段。该cDNA基因片段的氨基酸与已报道的烟芽夜蛾(Heliothis viresce)的GABAa受体基因氨基酸序列同源性为100%。以GABAa受体基因片段为基础, 构建了优化的半定量RT-PCR法, 以18S rRNA为内标, 研究小菜蛾不同组织以及不同发育阶段GABAa受体基因表达的差异。结果表明, GABAa受体基因在头部表达量最高, 胸部次之, 腹部最低; 在不同发育阶段的表达量差异不大。     

砧木对柑桔嫁接幼树早果影响的生理生化研究

本文研究了枳和红桔两种砧木对柑桔嫁接幼树结果早晚影响的生理生化差异。1.枳砧树较红桔树至少提早二年开花,枳砧树的单叶面积、株高、新梢生长量和干径均小于红桔砧树;2.花芽生理分化期枳砧树叶片的可溶性糖、淀粉及还原糖的含量均高于红桔砧树,叶片总氮含量变化不大,但在花芽形态分化期,砧木对叶片可溶性蛋白质含量的影响较大。叶片C/N比值与花芽形成存在一定相关关系。10月上中旬各因子二种砧木树的相对含量有一明显逆转过程,3.花芽生理分化期枳砧树叶片内源玉米素和脱落酸含量高于红桔砧树,赤霉素(GA_3)低于红桔砧树,整个试验期间,Z/GA_3和ABA/GA_3比值均为枳砧树高于红桔砧树。     

龟甲冬青枝枯病及其病原菌鉴定

于2002-2005年连续3年观察了杭州龟甲冬青枝枯病的症状,该病害先在嫩枝枝条发病,病斑初为水渍状斑点,后扩大成暗褐色的不规则形病斑。从发病部位分离培养出病原菌,根据其分生孢子的形态、大小和核糖体DNA内转录间隔区的序列,鉴定为褐纹拟茎点霉［Phomopsis vexans (Sacc.et Syd.) Harter］。本文对该病害症状和病原形态特征进行了描述。