红彩瑞猎蝽对草地贪夜蛾幼虫的控害能力

为明确红彩瑞猎蝽Rhynocoris fuscipes Fabricius成虫对草地贪夜蛾Spodoptera frugiperda J. E. Smith幼虫的控害潜能,室内条件下研究了不同饥饿时间处理红彩瑞猎蝽对草地贪夜蛾3龄幼虫的捕食功能反应、自身密度干扰效应和搜寻效应。结果表明,饥饿0 h、24 h、48 h、72 h和96 h条件下,红彩瑞猎蝽雌、雄成虫对草地贪夜蛾3龄幼虫的功能反应符合Holling Ⅱ型功能反应方程;饥饿程度对红彩瑞猎蝽24 h内捕食量影响明显,饥饿48 h和72 h处理的红彩瑞猎蝽对草地贪夜蛾具有更旺盛的捕食欲,其捕食速度曲线分别为v=0.9047-0.0592t+0.009t2和v=1.1512-0.0702t+0.0011t2,对草地贪夜蛾的捕食量随着时间的变化模型分别为Na=20/（1+e1.968-0.79t)和Na=20/（1+e1.689-0.93t）。不同饥饿程度红彩瑞猎蝽搜寻效应随猎物密度的增加而逐渐降低,其个体间竞争和干扰作用与天敌自身密度变化呈正比,符合Hassell-Varley模型。结果表明,红彩瑞猎蝽成虫对草地贪夜蛾幼虫有较好的防治潜力。     

草地贪夜蛾幼虫在苗期玉米田的空间分布格局及其抽样技术

草地贪夜蛾Spodoptera frugiperda(Smith)是2019年1月新入侵我国的重要害虫,研究并明确空间格局对确定该虫田间抽样技术、调查虫情具有指导意义。本研究调查获得了玉米苗期喇叭口初期、大喇叭口期草地贪夜蛾幼虫空间分布数据,应用多个聚集指标、Iwao m~*-m模型、Taylor幂法则等方法分析明确了该虫幼虫空间格局,发现苗期整体上幼虫个体群为聚集分布,喇叭口初期为聚集分布而大喇叭口期为均匀分布;苗期整体上及大喇叭口期幼虫聚集度对密度不具依赖性,而喇叭口初期幼虫聚集度对密度具依赖性;同一幼虫密度和误差条件下不同苗期抽样数量显著不同,玉米生育期越早则抽样数量越大。     

模拟降雨对草地贪夜蛾卵和幼虫的影响

为探究降雨对草地贪夜蛾Spodoptera frugiperda种群的影响,本研究通过室外模拟降雨研究了雨水冲刷对草地贪夜蛾卵和幼虫的影响。结果表明：在4种不同降雨强度0 mm/h（对照）、10.2 mm/h（中雨）、26.5 mm/h（暴雨）、42.8 mm/h（大暴雨）处理下,卵块的掉落率随着降雨强度的增加而增加;在暴雨、大暴雨条件下卵块的孵化率分别为75.14%、43.58%,显著低于对照和中雨;对比有无鳞毛层覆盖的卵块之间的掉落率和孵化率,二者在各个降雨强度之间差异不显著;对比玉米叶片不同位置卵块的掉落率和孵化率,在中雨降雨强度影响下,二者差异不显著,而在暴雨、大暴雨条件下,玉米叶片背面卵块的掉落率低于正面,孵化率高于正面。此外,在相同的降雨强度下,草地贪夜蛾幼虫（2龄、3龄、4龄、5龄）的掉落率随着龄期的增加而降低;当降雨强度增加时,3龄幼虫的掉落率增加。结果表明降雨,特别是暴雨和大暴雨,对草地贪夜蛾的卵和幼虫均有不利影响,为预测草地贪夜蛾种群提供一定依据。     

草地贪夜蛾幼虫自残捕食量分析

为了明确草地贪夜蛾Spodoptera frugiperda幼虫对同类低龄幼虫的捕食作用,在实验室条件下研究了草地贪夜蛾3~6龄幼虫对不同密度2龄幼虫和4~6龄幼虫对不同密度3龄幼虫的日捕食量,同时从捕食功能的角度解析了草地贪夜蛾高龄幼虫对低龄幼虫的捕食行为;并对不同龄期幼虫进行称重比较,用不同龄期幼虫间的重量关系来替换不同龄期幼虫间的捕食量,得到不同龄期幼虫间的捕食量方程。结果表明,草地贪夜蛾3~6龄幼虫对2龄幼虫和4~6龄幼虫对3龄幼虫的捕食功能反应均符合Holling Ⅱ型功能反应类型。草地贪夜蛾3~6龄幼虫对2龄幼虫的最大捕食量分别为76.47头、85.70头、117.92头、96.05头;4~6龄幼虫对3龄幼虫的最大捕食量分别为38.83头、59.49头、58.87头。高龄幼虫对低龄幼虫的捕食量随猎物密度的增加而增加。最大理论捕食质量方程y=47.231x^0.4591,捕食者的捕食量随着猎物虫态的增大而逐渐减小。研究结果为理解草地贪夜蛾幼虫的种间自残行为规律奠定了一定的理论基础。     

棉铃虫齿唇姬蜂对草地贪夜蛾幼虫的室内寄生效果初探

重大入侵害虫草地贪夜蛾Spodoptera frugiperda J. E. Smith主要危害玉米、水稻等主粮作物,对我国粮食安全造成了极大的威胁,挖掘和利用本土天敌是其绿色防控的重要途径之一。本研究以田间获取的寄生于草地贪夜蛾幼虫的棉铃虫齿唇姬蜂Campoletis chlorideae Uchida为研究对象,对其寄生草地贪夜蛾幼虫的完整过程进行了系统地观察,测定了其寄生于不同龄期草地贪夜蛾幼虫的发育历期。同时,进行了以不同夜蛾科幼虫为寄主时棉铃虫齿唇姬蜂的发育历期和蛹重的差异性分析。结果显示,棉铃虫齿唇姬蜂能够成功寄生2~4龄草地贪夜蛾幼虫,并顺利化蛹。但寄生2龄幼虫的棉铃虫齿唇姬蜂蛹期为4.21±0.52 d,蛹重为6.86±1.27 mg,均显著低于寄生3龄和4龄幼虫。寄生草地贪夜蛾幼虫的棉铃虫齿唇姬蜂的发育历期和蛹重分别为7.35±0.44 d和11.37±0.36 mg,与寄生棉铃虫Helicoverpa armigera Hübner和黏虫Mythimna separate Walker幼虫时无显著差异,但均显著高于寄生在斜纹夜蛾Spodoptera litura Fabricius幼虫时。研究表明,棉铃虫齿唇姬蜂对入侵害虫草地贪夜蛾具有良好的防控潜力,值得进一步研究和开发应用。     

A simple and inexpensive method of solid-state cultivation

Summary A simple and inexpensive procedure is described for the solid-state cultivation of fungi in plastic bags. This procedure, which provides for aeration, humidification and temperature control, may be used for extracellular enzyme production or upgrading of agricultural residues. It should be especially useful where resources are limited.     

虫螨腈对草地贪夜蛾幼虫的室内毒力及田间防效

草地贪夜蛾Spodoptera frugiperda(J. E. Smith),是一种广泛存在于美洲的杂食性农业害虫。据报道2019年1月草地贪夜蛾入侵我国云南,截止2019年6月6日,已在全国18个省份的884个县(市、区)监测到发生为害,发生面积342万亩,已经对我国粮食安全造成重大威胁。在2019年5月,在广东省广州市花都区儒林村玉米田开展喷雾和喇叭口点施虫螨腈对草地贪夜蛾幼虫的防治试验以及室内毒力测定试验。试验结果表明,虫螨腈对草地贪夜蛾2龄幼虫具有良好的毒力活性;综合考虑在草地贪夜蛾1～3龄幼虫期,用药量67.5 g.a.i/hm~2、药液量675 L/hm~2常规喷雾效果更佳;在草地贪夜蛾4～6龄幼虫期,用药量22.5 g.a.i/hm~2、药液量225 L/hm~2喇叭口点施效果更佳,且喇叭口点施可以定位定向定量地直接到达草地贪夜蛾为害部位,可减少2/3的农药使用量,达到农药减量增效的目的。该研究结果为拟定草地贪夜蛾应急防控技术方案提供技术支撑和理论依据。     

环斑猛猎蝽对草地贪夜蛾低龄幼虫的捕食功能分析

为探究环斑猛猎蝽Sphedanolestes impressicollis St?l对草地贪夜蛾Spodoptera frugiperda Smith的捕食潜能,在室内条件下研究了环斑猛猎蝽4龄若虫对草地贪夜蛾1～3龄幼虫的捕食功能、搜寻效应以及环斑猛猎蝽自身密度对捕食草地贪夜蛾的干扰作用。结果表明：环斑猛猎蝽4龄若虫对草地贪夜蛾低龄幼虫的捕食功能反应符合Holling II模型。环斑猛猎蝽4龄若虫对草地贪夜蛾1龄、2龄、3龄幼虫的瞬时攻击率分别为0.900、1.229和1.259,处理时间分别为0.018 d、0.050 d和0.205 d,日最大捕食量分别为55.897头、19.853头和4.871头。环斑猛猎蝽4龄若虫的搜寻效应与草地贪夜蛾密度呈负相关。环斑猛猎蝽4龄若虫对草地贪夜蛾低龄幼虫的捕食作用率随自身密度的增加而降低。在捕食草地贪夜蛾1龄幼虫时,环斑猛猎蝽4龄若虫自身密度对其捕食能力干扰最大。研究结果表明环斑猛猎蝽4龄若虫对草地贪夜蛾低龄幼虫有一定的捕食能力,为其田间应用释放技术提供了理论依据。     

Purification and properties of a beta-glycosidase purified from midgut cells of Spodoptera frugiperda (Lepidoptera) larvae

Two beta-glycosidases (BG) (Mr 47,000 and Mr 50,000) were purified from Spodoptera frugiperda (Lepidoptera: Noctuidae) midguts. These two polypeptides associate or dissociate depending on the medium ionic strength. The Mr 47,000 BG probably has two active sites. One of the putative active sites (cellobiase site) hydrolyses p-nitrophenyl beta-D-glucoside (NPbetaGlu) (79% of the total activity in saturated enzyme), cellobiose, amygdalin and probably also cellotriose, cellotetraose and cellopentaose. The cellobiase site has four subsites for glucose residue binding, as can be deduced from cellodextrin cleavage data. The enzymatic activity in this site is abolished after carbodiimide modification at pH 6.0. Since the inactivation is reduced in the presence of cellobiose, the results suggest the presence of a carboxylate as a catalytic group. The other active site of Mr 47,000 BG (galactosidase site) hydrolyses p-nitrophenyl beta-D-galactoside (NPbetaGal) better than NPbetaGlu, cleaves glucosylceramide and lactose and is unable to act on cellobiose, cellodextrins and amygdalin. This active site is not modified by carbodiimide at pH 6.0. The Mr 47,000 BG N-terminal sequence has high identity to plant beta-glycosidases and to mammalian lactase-phlorizin hydrolase, and contains the QIEGA motif, characteristic of the family of glycosyl hydrolases. The putative physiological role of this enzyme is the digestion of glycolipids (galactosidase site) and di- and oligosaccharides (cellobiase site) derived from hemicelluloses, thus resembling mammalian lactase-phlorizin hydrolase.     

7种生物杀虫剂对草地贪夜蛾和粘虫幼虫的毒力与防效

草地贪夜蛾Spodoptera frugiperda和粘虫Mythimna separata是我国玉米上的重要害虫,二者在田间混合发生,对玉米安全生产构成严重威胁.为筛选同时控制草地贪夜蛾与粘虫的高效生物杀虫剂,采用饲料药膜法和喷雾法分别测定了7种生物杀虫剂对草地贪夜蛾和粘虫2龄幼虫的室内毒力和田间防效.室内生测结果表...     

A hemagglutinating antigen from a nuclear polyhedrosis virus of Spodoptera frugiperda

The 100,000g supernatant from an alkaline dissolution of polyhedra isolated from an NPV of Spodoptera frugiperda was found to agglutinate adult chicken erythrocytes in a pH range of 5.5–6.9. Optimal conditions for active hemagglutination and hemagglutination-inhibition, with antisera prepared against polyhedron protein, occurred at pH 5.8 with an incubation temperature of 37°C and a solublization time of 45 min at pH 11.2 Minimum quantities of antigen detectable were at 2–4 μg/ml of protein.     

Characterisation of a Colombian granulovirus (Baculoviridae: Betabaculovirus) isolated from Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae

A strategy for biological control of the fall armyworm, Spodoptera frugiperda, has included the use of baculoviruses principally the nucleopolyhedrovirus SfMNPV, which have been extensively characterised. In contrast, the granulovirus of S. frugiperda (SfGV) has been poorly studied even though it is able to enhance the infectivity and virulence of NPVs. In this work, a Colombian SfGV isolate (VG008) was characterised in comparison with a reference isolate from Brazil (VG014). The viral morphology was characterised by ovoidal-shaped occlusion bodies (OB) that contained one single internal virion. Median lethal concentrations (LC₅₀) and mean times to death (MTD) were 4.5 × 10⁵ OBs/mL and 29 days for VG008 and 1.6 × 10⁵ OBs/mL and 33 days for VG014. Both isolates reduced their insecticidal activity by 94%, after one hour of direct irradiation with ultraviolet light type B. The most prominent protein had an apparent molecular mass of 27 kDa and corresponded with the Granulin. Genomic comparison among isolates from Colombia and Brazil generated by restriction profiles showed differences in the number and size of fragments. Partial sequences of lef-8 and lef-9 genes and complete sequence of gran gene of Colombian SfGV isolate (VG008) showed high similarity values with VG014 and SfGV A12-4 homologous sequences, showing genetic distance lower than 0.015 (Kimura 2-parameter model), which confirmed that the three isolates belong to the same viral species. The characterisation of VG008 isolate demonstrated its high genomic and biological similarity with the Brazilian isolate.     

Response of nuclear polyhedrosis virus-resistant Spodoptera frugiperda larvae to other pathogens and to chemical insecticides

Selection in the laboratory for Spodoptera frugiperda (Sf) resistant to nuclear polyhedrosis virus (NPV) affected the susceptibility of the insect to certain other mortality agents, including a chemical insecticide. Median lethal concentrations (LC50S) and associated statistics were compared for several mortality agents between colonies of NPV-resistant and -susceptible (control) insects. Compared to the susceptible insects, the NPV-resistant insects were cross-resistant to the S. frugiperda granulosis virus and to the Autographa californica NPV based on nonoverlap of 95% fiducial limits of the LC50S. The NPV-resistant insects were significantly more susceptible to methyl parathion than the control insects. The two colonies of S. frugiperda did not differ significantly in their response to Bacillus thuringiensis, Vairimorpha necatrix, or carbaryl. The cross-resistance experiments were based on per os exposure of the insects to the pathogens and insecticides; the susceptibility of the resistant and control insects did not differ significantly when the Sf NPV was injected into the hemocoel or when methyl parathion was applied topically.     

A simple and inexpensive method for producing fluorescently labelled size standard

Current methods of automated genotyping offer many advantages over traditional gel‐based approaches, including reduced handling and processing times, and increased accuracy and consistency. Unfortunately, these advances have come at a substantial cost; at present, roughly one‐half of the cost of automated genotyping is due to fluorescently labelled internal size standard. Here we describe detailed methodologies for generating a highly consistent, fluorescently labelled, internal size standard using polymerase chain reaction (PCR). The methods are simple and the required reagents are inexpensive, making the in‐house production of fluorescently labelled size standards a more widely accessible alternative to commercially available size standards.     

Horseradish peroxidase catalyzed hydroxylations: mechanistic studies

The hydroxylation of phenol to hydroquinone and catechol in the presence of dihydroxyfumaric acid and oxygen catalyzed by horseradish peroxidase was studied under conditions where the product yield was high and the side reactions were minimal. The reaction is partially uncoupled with a molar ratio of dihydroxyfumaric acid consumed to hydroxylated products of 12:1. Hydrogen peroxide does not participate in the reaction as evidenced by the lack of effect of catalase and by the direct addition of hydrogen peroxide. Conversely, superoxide and hydroxyl radicals are involved as their scavengers are potent inhibitors. Experiments were all consistent with the involvement of compound III (oxygenated ferrous complex) of peroxidase in the reaction. Compound III is stable in the presence of phenol alone but decomposes rapidly in the presence of both phenol and dihydroxyfumaric acid with the concomitant formation of product. Therefore, phenol and dihydroxyfumaric acid must be present with compound III in order for the hydroxylation reaction to occur. A mechanism consistent with the experimental results is proposed.     

Effect of parasitism on a nucleopolyhedrovirus amplified in Spodoptera frugiperda larvae parasitized by Campoletis sonorensis

We evaluated the consequences of parasitism by the solitary ichneumonid endoparasitoid Campoletis sonorensis(Cameron) towards the replication, genetic composition and virulence of a nucleopolyhedrovirus (Baculoviridae) originating from Spodoptera frugiperda(J. E. Smith) larvae. Parasitism by C. sonorensisand viral infection of third and fourth instar S. frugiperdalarvae resulted in reduced growth compared with nonparasitized control larvae. A positive correlation was observed between virus yield and larval instar at the moment of infection. When larvae were virus-inoculated in the fourth instar, parasitism resulted in a significant reduction in mean per capita virus yield compared to the virus yield from nonparasitized larvae. In an experiment involving 10 serial passages of virus in both parasitized and nonparasitized larvae, restriction endonuclease analysis of viral DNA amplified in nonparasitized larvae revealed the presence of the wild-type virus as well as three additional variants (A, B, and C) diagnosed by the presence of novel submolar PstI fragments of different sizes. In contrast, analysis of viral DNA from parasitized larvae showed the presence of the wild-type virus and two other variants (E and F), each characterized by a different submolar BglII fragment. Southern blot analysis indicated that the submolar fragments of variants E and F contained sequences originating from the viral genome. Bioassay of the different virus variants in S. frugiperdalarvae indicated that their virulence was equal or less than that of the wild-type virus. We conclude that parasitism can affect the quantity of virus produced in dually infected and parasitized larvae, but no adverse effects were detected in terms of the biological activity of the virus.