乙基多杀菌素对草地贪夜蛾幼虫的毒力及对其解毒酶和乙酰胆碱酯酶活性的影响

【目的】为了研究乙基多杀菌素对草地贪夜蛾Spodoptera frugiperda幼虫的毒力及作用机制。【方法】以氯虫苯甲酰胺为对照,采用表面涂抹法测定了乙基多杀菌素对草地贪夜蛾2, 3和4龄幼虫的LC50和LC90。采用酶联免疫吸附法(ELISA),测定不同浓度乙基多杀菌素(0.127, 0.183, 0.250, 0.400和0.572 mg/L)处理48 h后草地贪夜蛾3龄幼虫体内多功能氧化酶(MFO)、谷胱甘肽-S-转移酶(GST)、羧酸酯酶(CarE)以及乙酰胆碱酯酶(AchE)的活性。【结果】与氯虫苯甲酰胺相比,乙基多杀菌素对草地贪夜蛾幼虫具有更高的毒力,处理48 h后对2, 3和4龄幼虫的LC50值分别为0.21, 0.34和0.59 mg/L, LC90值分别为0.59, 0.75和2.01 mg/L。经过乙基多杀菌素处理后,草地贪夜蛾3龄幼虫体内MFO和AchE活性均表现随着浓度的增加而显著增加,二者均在0.572 mg/L处理时活性最高,分别为52.23和23.98 U/mg pro;CarE活性在低浓度乙基多杀菌素处理(0.127和0.183 mg/L)下相对于溶剂对照(0.1%Tween-80)无显著变化,随着浓度增加至0.400与0.572 mg/L时,其活性显著增加;GST活性表现为随着乙基多杀菌素浓度增加而增加的特点,当处理浓度为0.400与0.572 mg/L时,其活性无显著性差异。【结论】乙基多杀菌素对草地贪夜蛾幼虫的杀虫效果优于氯虫苯甲酰胺,尤其对4龄幼虫效果最为明显;在不同浓度的乙基多杀菌素处理条件下,草地贪夜蛾幼虫体内的CarE, MFO和AchE活性有所增高。

京科968花丝抗螟性评价及其抗性机制研究

玉米品种京科968具有众多综合优良特性,是北方春玉米区的主栽品种。为了解京科968穗期对亚洲玉米螟的抗性水平,并探明其抗螟机制,本试验选取京科968,其母本京724和父本京92,以及自330等4个玉米品种(系)作为供试玉米材料,其中自330作为感螟对照。通过实验种群生命表技术对取食4个玉米品种(系)花丝的亚洲玉米螟种群的生命表参数进行评价,并对花丝中营养物质、防御酶以及丁布类等化合物的含量进行分析。生命表结果显示,4个玉米品种(系)抗螟性大小依次为:京92>京科968>京724>自330。与京724和感虫对照自330相比,取食京科968花丝的亚洲玉米螟发育历期延长,平均世代周期长,说明京科968的花丝具有一定抗螟效果;生化分析结果显示京科968花丝中的具有较高的可溶性糖、可溶性蛋白质、多酚氧化酶和超氧化物歧化酶含量,而DIMBOA和DIMBOA-Glc的含量均较低,说明玉米防御酶可能在花丝抗螟中发挥重要作用。

基于Cytb基因的秆野螟属(Ostrinia)昆虫遗传多样性及其系统发育研究

为阐明秆野螟属(Ostrinia)昆虫遗传多样性、系统发育及其种间亲缘关系,为秆野螟属昆虫的物种分化与鉴定研究奠定理论基础,利用DNAMAN 8.0、PAUP 4.0和MEGA 7.0等生物信息学软件对我国秆野螟属8个物种线粒体Cytb基因的碱基组成、碱基变异和偏向性等进行了分析,分别利用最大似然法(ML)、贝叶斯法(BI)和最大简约法(MP)重建其系统发育关系。结果表明:线粒体Cytb基因序列长度为1146bp,碱基组成和密码子碱基分布都表现出较强的AT偏向性;种间保守性位点1051个,可变性位点95个,变异率为8.29%;亚洲玉米螟6个不同地理种群间Cytb基因碱基差异位点0~4个,遗传距离在0~0.0052之间;种间遗传距离在0.0009~0.0698之间;所有样本Cytb基因的碱基替换随着遗传距离的增大呈现出明显的线性关系;利用ML、BI和MP法构建的系统发育关系基本一致,即8种秆野螟属昆虫分为亮大支系,虎杖螟单独形成一支系,亚洲玉米螟等7种螟虫聚在一起形成另一支系。秆野螟属昆虫线粒体Cytb基因序列多样性低,种间界限不明显;进化关系与传统分类结果基本一致。

Molecular Taxonomy of Conogethes punctiferalis and Conogethes pinicolalis(Lepidoptera: Crambidae) Based on Mitochondrial DNA Sequences

Conogethes punctiferalis（Guenée）（Lepidoptera： Crambidae） was originally considered as one species with fruit-feeding type（FFT） and pinaceae-feeding type（PFT）, but it has subsequently been divided into two different species of Conogethes punctiferalis and Conogethes pinicolalis. The relationship between the two species was investigated by phylogenetic reconstruction using maximum-likelihood（ML） parameter estimations. The phylogenetic tree and network were constructed based upon sequence data from concatenation of three genes of mitochondrial cytochrome c oxidase subunits I, II and cytochrome b which were derived from 118 samples of C. punctiferalis and 24 samples of C. pinicolalis. The phylogenetic tree and network showed that conspecific sequences were clustering together despite intraspecific variability. Here we report the results of a combined analysis of mitochondrial DNA sequences from three genes and morphological data representing powerful evidence that C. pinicolalisand C. punctiferalis are significantly different.

Acquisition of Insect-Resistant Transgenic Maize Harboring a Truncated cry1Ah Gene via Agrobacterium-Mediated Transformation

A novel insecticidal gene crylAh was cloned from Bacillus thuringiensis isolate BT8 previously for plant genetic engineering improvement. Truncated active CrylAh toxin has a toxicity level similar to that of the full-length CrylAh toxin. In this study, plant expression vector pMhGM harboring truncated crylAh gene was transformed into maize （Zea mays L.） immature embryos by Agrobacterium tumefaciens-mediated transformation at which maize alcohol dehydrogenase matrix attachment regions （madMARs） were incorporated on both sides of the gene expression cassette to improve gene expression. A total of 23 PCR positive events were obtained with a transformation efficiency of 5% around. Bioassay results showed that events 1-4 and 1-5 exhibited enhanced resistance to the Asian corn borer （Ostriniafurnacalis）. These two events were further confirmed by molecular analysis. Southern blot suggested that a single copy of the crylAh gene was successfully integrated into the maize genome. Western blot and ELISA showed that the foreign gene crylAh was expressed stably at high level in maize and could be inherited stably over generations. The results of a bioassay of T l-T4 transgenic maize plants indicated that the transgenic plants were highly toxic to the Asian corn borer and their resistance could be inherited stably from generation to generation. Thus, events 1-4 and 1-5 are good candidates for the breeding of insect-resistant maize.

Quantitative Trait Loci for Asian Corn Borer Resistance in Maize Population Mc37×Zi330

Asian corn borer, Ostrinia furnacalis （Guen6e）, is the most important pest of maize in China and Southeast Asia. The objective of this study was to understand the genetic basis for Asian corn borer resistance. The study included 162 F2：3 populations derived from Mc37 （resistant） × Zi330 （susceptible） and field data were collected in 2004 and 2005. A linkage map was constructed from 118 SSR markers. Combined quantitative trait loci （QTL） analysis combined across environments was performed by composite interval mapping method （CIM）. Four QTLs with additive effects were detected for resistance to Asian corn borer leaf feeding damage in chromosome bins 1.08, 2.04/05, 4.01, and 10.04. Three putative QTLs were detected for Asian corn borer stalk damage in chromosome bins 1.01, 2.05, and 9.01. Maize resistance to Asian corn borer and European corn borer, O. nubilalis （Hubner）, may share a common mechanism. Genes responsible for DIMBOA biosynthesis are in chromosome bin 4.01 and may increase the observed resistance to Asian corn borer leaf feeding.

Developing transgenic maize(Zea mays L.) with insect resistance and glyphosate tolerance by fusion gene transformation

Using linker peptide LP4/2A for multiple gene transformation is considered to be an effective method to stack or pyramid several traits in plants. Bacillus thuringiensis（Bt） cry gene and epsps（5-enolpyruvylshikimate-3-phosphate synthase） gene are two important genes for culturing pest-resistant and glyphosate-tolerant crops. We used linker peptide LP4/2A to connect the Bt cry1 Ah gene with the 2m G2-epsps gene and combined the wide-used man A gene as a selective marker to construct one coordinated expression vector called p2 EPUHLAGN. The expression vector was transferred into maize by Agrobacterium tumefaciens-mediated transformation, and 60 plants were obtained, 40% of which were positive transformants. Molecular detection demonstrated that the two genes in the fusion vector were expressed simultaneously and spliced correctly in translation processing; meanwhile bioassay detection proved the transgenic maize had preferable pest resistance and glyphosate tolerance. Therefore, linker peptide LP4/2A provided a simple and reliable strategy for producing gene stacking in maize and the result showed that the fusion gene transformation system of LP4/2A was feasible in monocot plants.

Olfactory Response of Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) to Volatiles Emitted by Mungbean Plants

Intercropping maize with the prostrate variety of mungbean, Vigna radiata （L.） Wilczek which grows flat along the ground can increase parasitism of the eggs of the Asian corn borer, Ostrinia furnacalis （Guenée）, a crucial insect pest of maize in China, by Trichogramma ostriniae Pang Chen. This study investigated the behavioural responses of T. ostriniae to plant volatiles emitted from whole plants, leaves, and flowers of prostrate and erect varieties of mungbean in a 4-armed olfactometer. Female parasitiods were significantly attracted to the odours from some varieties of prostrate mungbean when the visit duration and the number of visits were considered, but were not attracted to the odours from any erect varieties. The attractive odours were shown to emanate from the leaves, rather than from the flowers of prostrate mungbean plants. These results have implications for the augmentation of Trichogramma parasitoids in bio-control of O. furnacalis and other crop pests.

Wolbachia Infection in Populations of Ostrinia furnacalis: Diversity, Prevalence, Phylogeny and Evidence for Horizontal Transmission

Wolbachia are maternally inherited endosymbiotic bacteria infecting a wide range of arthropods and filarial nematodes. They can induce various reproduction alterations in their hosts, including thelytokous parthenogenesis, cytoplasmic incompatibility （CI）, feminization of genetic males and male killing. Here we investigated diversity and prevalence patterns of Wolbachia infection in 43 geographical populations of the Asian corn borer, Ostriniafurnacalis, in China and one population in North Korea. Based on Wolbachia surface protein gene （wsp） sequences, nine strains of Wolbachia （wFurl-wFur9）, belonging to supergroups A and B, were identified in populations of O. furnacalis with an average infection rate of 10.5%. Superinfection commonly appeared in individuals of O. furnacalis and coinfection patterns were very complex. There was no specific pattern for the prevalence and distribution of the nine Wolbachia strains suggesting an intricate evolutionary history of Wolbachia infection in this species. The genetic similarity of the wFurl-wFur9 strains with those detected in two parasitoids of O. furnacalis, Macrocentrus cingulum and Lydella grisescens, strongly suggests host-parasitoid horizontal transmission.

Penetration of a Single Domain of Bacillus thuringiensis Cry1Ie-Domain I to a Lipid Membrane In vitro

Domain I of the activated Crystal protein from Bacillus thuringiensis has a seven a-helix bundle structure, which is responsible for membrane channel formation in its insecticidal mechanism. Crylle is toxic to Asian corn borer, Ostrinia furnacalis （Guen6e）, and plays important roles in insect biological control. The domain I from Crylle has been expressed and purified in its normal conformation, as embedded in the full length homologous toxin structure. The membrane insertion ability of this single domain was compared with the full length homologous toxin using a monolayer insertion experiment. The results indicated that the Crylle-domain I had the ability to insert into the lipid monolayer, and this ability is greater than that of the IE648 toxin. However, the state of insertion is not stable and remains for only a short period of time. The Crylle-domain I plays no role in receptor binding as it had a nonspecific binding with the brush border membrane vesicles of the Asian corn borer.

桃蛀螟在玉米、高粱和向日葵上发生为害与播期的关系

【目的】为了更好地掌握桃蛀螟的田间发生规律,明确播期对桃蛀螟在玉米、高粱和向日葵上发生为害的影响。【方法】分别在北京和河北廊坊,分3个播期种植玉米、高粱、向日葵,采用5点取样法调查桃蛀螟在不同播期3种作物上的产卵部位、产卵量;作物收获前剖秆调查桃蛀螟幼虫数量、被害部位和被害株率。【结果】从7月中下旬到10月,田间一直可查见桃蛀螟卵,成虫产卵的时期长,世代重叠严重。在玉米田,成虫产卵多在玉米的抽雄期、灌浆期和乳熟期,产卵部位主要为雄穗、花丝、叶鞘、雌穗上部叶片;在向日葵田,成虫在花盘抽出之后一直产卵,产卵的时期较长,卵主要产在苞片、蜜腺盘及萼片和管状花上。对同一播期的不同作物来说,桃蛀螟对向日葵的为害最重,其次是高粱,为害最轻的是玉米;不同播期,桃蛀螟对同种作物的为害程度不同,这与作物的生长感虫期能否避开桃蛀螟的发生高峰期有关。桃蛀螟在玉米上主要为害果穗,也钻蛀茎秆为害,在高粱上主要为害高粱穗部,在向日葵上则主要为害向日葵花盘。【结论】本研究明确了播期对桃蛀螟在玉米、高粱和向日葵上发生为害的影响,为桃蛀螟的监测预报与防控策略制定提供了科学依据。

草地贪夜蛾的生物学特性、发展趋势及防控对策

草地贪夜蛾Spodoptera frugiperda (Smith)是一种原产于美洲热带和亚热带地区的跨境迁飞性重大害虫,具有寄主范围广、繁殖能力强、迁飞扩散快、危害程度重和防控难度大的特点。草地贪夜蛾自2019年1月入侵我国云南省并在西南地区迅速定殖、蔓延,5月中旬进一步迁飞扩散至长江和江淮流域。预计6-7月份可能继续北迁至黄淮海夏玉米产区和北方春玉米产区,将严重威胁我国玉米生产安全。本文综述了草地贪夜蛾的生物学特性、在非洲和亚洲地区的暴发原因、发展趋势、防控措施,并提出了应对策略,以期为控制草地贪夜蛾在我国的传播为害提供参考。

东北玉米田除草剂减施增效技术途径探讨

以东北春玉米种植区为基地,分析杂草种群结构、发生规律和对玉米的产量损失。在此基础上,论述东北玉米田除草剂减施途径,包括高风险除草剂替代技术、除草剂高效使用技术和多策略除草剂减施技术,提出采用替代长残留除草剂莠去津和易漂移的除草剂2,4-滴,实施精准选药、适时用药、对靶喷药的3S施药技术,结合农作措施、生态措施、除草决策支持系统及加快耐除草剂玉米推广的多策略除草剂减施技术,实现除草剂减量,为东北玉米田除草剂减量增效实施提供技术指导。

靶标害虫对Bt玉米的抗性发展和治理策略

全生育期有效表达Bt杀虫蛋白的转基因抗虫玉米为靶标害虫的防治提供了新途径。但是,靶标害虫抗性种群的发展严重威胁了转基因抗虫玉米的可持续应用。截止到2018年,已经有13例报道表明靶标害虫对转基因抗虫玉米产生了田间抗性;5例监测结果表明靶标种群没有降低对Bt玉米的敏感性,其中包括转vip3Aa玉米。抗性治理策略成功的关键主要包括:Bt杀虫蛋白的高剂量表达、靶标害虫的隐性遗传、初始抗性等位基因频率较低、不完全抗性、适合度代价等。当抗性为非隐性遗传时,可以通过增加庇护所的种植面积达到延缓抗性发展的目的。

草地贪夜蛾对小葱和洋葱的潜在为害风险

【目的】为明确草地贪夜蛾Spodoptera frugiperda(J.E.Smith)对小葱和洋葱的潜在为害风险。【方法】本研究比较2种寄主植物小葱和洋葱对草地贪夜蛾生长发育的影响,并测定草地贪夜蛾雌蛾对这2种寄主植物的产卵选择行为。【结果】草地贪夜蛾在小葱和洋葱上能够顺利完成生活史实现种群繁衍,其中取食小葱的草地贪夜蛾幼虫的发育历期显著短于取食洋葱的。取食小葱的草地贪夜蛾成虫前期存活率为77%,显著高于取食洋葱的58%。取食小葱和洋葱的草地贪夜蛾成虫产卵前期差异不显著,但取食小葱的的总产卵前期显著长于取食洋葱的。此外,与取食洋葱相比,取食小葱的草地贪夜蛾成虫繁殖力和总的寿命虽有所增加,但差异不显著。种群生命表参数显示,取食小葱的草地贪夜蛾种群内禀增长率、净增殖率和周限增长率最高,平均世代周期最短。草地贪夜蛾雌蛾对小葱和洋葱不同部位具有明显的产卵选择性,草地贪夜蛾更偏好在洋葱上产卵,产卵部位以洋葱植株的中上部叶片为主。【结论】小葱和洋葱均为草地贪夜蛾适合寄主植物,而相对于洋葱,小葱是草地贪夜蛾更适合的寄主植物。草地贪夜蛾对2种寄主植物的产卵选择性和取食2种寄主对其后代发育适合度并不一致。这一结论为评估草地贪夜蛾在小葱和洋葱上潜在为害风险提供科学依据。

亚洲玉米螟蛀孔和越冬幼虫在玉米上的空间分布

在黑龙江齐齐哈尔,亚洲玉米螟一代幼虫蛀孔主要分布在玉米茎秆的中部,占总蛀孔数的69.6%;二代幼虫蛀孔主要分布在茎秆下部,占总蛀孔数的41.2%。越冬幼虫在玉米茎秆的中部和下部均有较多分布,分别占总活虫数的40.6%和36.6%。在吉林公主岭,玉米螟一、二代幼虫蛀孔主要分布在茎秆的中部,分别占总蛀孔数的47.3%和47.7%;越冬幼虫分布位置主要在茎秆下部,占总幼虫数的63.2%,在12月入冬后,茎秆下部的幼虫占总数的比率有所上升,达69.2%,次年化蛹前根茬中活虫数占比达24.3%。研究结果表明,北方春玉米二代玉米螟幼虫蛀孔在茎秆中的分布比一代蛀孔分布位置靠下,越冬幼虫主要分布在茎秆的中部和下部,且有下移趋势。