飞虱虫疠霉液培菌丝的凝胶化及其杀蚜活性

用丙烯酰胺淀粉凝胶包埋飞虱虫疠霉（Pandora delphacis)液培菌丝,制成含营养和不含营养的虫霉凝胶,并测试其产孢能力及对桃蚜（Myzus persicae)的侵染力。经持续9d产孢观察。相同菌丝量条件下,含营养的虫霉凝胶的累计产了解量（1910.9个/mm^2)为不含营养的虫霉凝胶的3.14倍（608.5个/mm^2)和对照（纯液培菌丝）的4.69倍（387.5个/mm^2)。用虫霉凝胶的“孢子浴”接种桃蚜居群（成蚜与不同龄期若蚜的混合）,在2.23个/mm^2的剂量下,接种后第7d的死亡率达82.3%。结果表明,丙烯酰胺淀粉凝胶作为载体材料,与飞虱虫疠霉的基本生物学特性相容,对虫霉的剂型化具有重要意义。     

飞虱虫疠霉杀蚜效果及开发应用前景

通过比较飞虱虫疠霉 (Pandoradelphacis)与其它几种常见蚜虫专化性病原真菌新蚜虫疠霉(P .neoaphidis)、安徽虫瘟霉 (Zoothphoraanhuiensis)和根虫瘟霉 (Z .radicans)对桃蚜 (Myzuspersicae)毒力 ,证实了该菌的杀蚜应用潜力。时间 -剂量 -死亡率模型分析表明 ,飞虱虫疠霉杀蚜的各项毒力指标与其它几种虫霉相似或略高 ,但杀蚜速率更快。同时对培养性状、产孢特性和生长适温等的比较研究发现 ,该菌具有易发酵生产、产孢能力强和温度生长范围宽等特点 ,是一种较为理想的有望研制开发成杀蚜真菌制剂的病原菌。此外 ,根据虫霉孢子主动弹射的生物学特性 ,提出了该菌的适用剂型 ,并对它们的流行学特性及其在设栽培中的应用前景进行了讨论。     

光周期对飞虱虫疠霉离体培养的生物量及其产孢节律的影响

飞虱虫疠霉（Ｐａｎｄｏｒａｄｅｌｐｈａｃｉｓ）是侵染飞虱和叶蝉等重要作物害虫的昆虫病原真菌。通过在液体及平板培养中研究光周期对菌丝及菌落生长量、产孢节律和产孢量的影响,作者发现光照对液培菌丝的营养生长无显著影响,但长光照液培菌丝的产孢延迟并且产孢量减少,而全黑暗液培菌丝产孢早且产孢量大。但是,光照明显促进全黑暗下液培菌丝的产孢。在平板培养中,长光照能促进菌落生长和产孢;半光照半黑暗虽有利菌落生长,但产孢量很低;光照９ｈ和１８ｈ产孢量较大,但菌落生长较小。无论液体还是平板培养,飞虱虫疠霉均生长良好,但建议在全黑暗条件下进行液体培养,在长光照下进行平板培养。     

不同温湿度条件下飞虱虫疠霉对桃蚜生殖力和内禀增长力的影响

对7日龄桃蚜 Myzus persicae用高剂量飞虱虫疠霉Pandora delphacis接种后,饲养于不同温(10～30℃)、湿(74%～100%RH)度组合条件下观察其生殖力及内禀增长力(r_m) 的变化。结果表明,被接种个体生殖力比对照显著降低,且下降幅度受温度、湿度及温湿互作的影响。在各处理组合中,尤其以20～30℃和95%～100%RH的条件下下降更为明显。各处理r_m在不同温度间差异显著,均随温度呈抛物线形变化,25℃下达最高,但不同湿度间差异不显著。与对照相比,被接种蚜的r_m>除10℃与各湿度组合间无显著差异外,其余温湿组合下均显著低于对照。上述分析表明,飞虱虫疠霉的侵染能显著影响桃蚜生殖力及r_m,尤其是在桃蚜繁殖的最适温度范围内效果最为明显。     

飞虱虫疠霉继发性感染对桃蚜数量增长的控制作用

用飞虱虫疠霉（Pandora delphaics)“孢子浴”接种的桃蚜(Myzus persicae)无翅成蚜在离体甘蓝菜叶片（65cm^2)上建立蚜群,在不同温度（10－30℃）和湿度（74％－100％RH）的组合条件下任其繁衍,发病和交互感染,以评价该菌的控蚜效果。在25个温,湿度组合处理（8次重复,每重复含3头接种成蚜)中,蚜群均不同程度的发病死亡,在历时30d的观察中,以高温（20－30℃）,高湿（95％RH）组合条件下的蚜群发病快且死亡率高,蚜尸上产生的孢子有效地引起若蚜继发性感染。与相同温度下不带菌的对照蚜群相比,次于30℃下,各湿度除个别例外,第8d的控蚜率达30％以上,第20d达80％以上。在10℃和15℃下,控蚜效果一般不如上述较高温度下,且与湿度的关联程度相对较低,但最大控蚜效果均发生在100％RH处理中。结果表明,飞虱虫疠霉用于蚜虫防治的潜力很大,值得深入研究和开发利用。     

光周期对飞虱虫疠霉离体培养的生物量及其产孢节律的影响

飞虱虫疣霉时侵染飞虱和叶蝉等重要作物害虫的昆虫病原真菌。通过在液体及平板培养中研究光周期对菌丝及菌落生长量,产孢节律和产孢量的影响,作者发现光照对液培菌丝的营养生长无显著影响     

努利虫疠霉感染桃蚜过程的扫描电镜观察

利用扫描电镜观察了努利虫疠霉Pandora nouryi (Remaudière & Hennebert) Humber初生分生孢子接种桃蚜Myzus persicae (Sulzer)后孢子萌发、入侵以及菌体突破虫体的整个侵染过程。结果表明：附着于虫体表面的初生分生孢子在3～5 h后即有60%以上的萌发率,萌发的孢子形成芽管或产生球形或棍棒状的附着胞;12 h后大部分孢子均已萌发,并成功入侵寄主虫体;接种60 h后,呈掌状分枝的假根首先从桃蚜胸部的腹面突破虫体长出体外,明显区别于新蚜虫疠霉Pandora neoaphidis (Remaudière & Hennebert) Humber假根突破虫体的位置;假囊状体不多见,且仅分布于蚜虫身体两侧,这可在一定程度上解释努利虫疠霉产孢对湿度条件要求较高的生物学现象。     

不同温湿度组合对安徽虫瘟霉 诱发桃蚜病害的影响

用孢子浴方法,对42批次桃蚜Myzus persicae（30～60头/批）接种大剂量（孢子79～90个/ mm²）安徽虫瘟霉Zoophthora anhuiensis的分生孢子,在20℃下保湿24 h后转入不同温度（10℃、15℃、20℃、25℃、30℃及自然变温1.5～16.6℃和8.5～20.2℃）和湿度(50%、65%、80%、90%、95%及100% RH)的组合条件下观察桃蚜的反应。结果表明,各组合条件下的桃蚜均能发病死亡,而且累计死亡率的显著差异存在于不同温度（F=7.46, P<0.01)和湿度间（F=12.54, P<0.01）。最适发病的温度为恒温20℃和变温8.5～20.2℃（日均温12.4℃）,死亡率随湿度升高而增大。在10～25℃和100% RH的组合中,温度的变化几乎不影响桃蚜的累计死亡率,但影响发病速率,在10℃、15℃、20℃和25℃下的致死时间LT₅₀值分别为8.4 天、7.1 天 、4.0 天和3.4 天。回归分析表明, 在100% RH下安徽虫瘟霉诱发桃蚜发病的起始温度为1.65℃。在10～15℃及自然变温下,病死蚜尸顺利产孢的湿度为80% RH;而在20～30℃下,蚜尸产孢的湿度为90% RH。在所有温湿组合的蚜尸中未见安徽虫瘟霉的休眠孢子发生。     

飞虱虫疠霉分生孢子在桃蚜体壁上的附着与入侵

用飞虱虫疠霉（Pandora delphacis)初级分生孢子接种桃蚜（Myzus persicae),24h内定时取样,在扫描电镜下观察孢子的萌发及其对寄主体壁的入侵。结果表明,附着到蚜体表面的孢子在4h内有30－40％已萌发产生芽管,少数是呈叉状分枝的营养生长型芽管。且侵染性芽管的孢子部分孢入体壁蜡质层中,显示孢子有分泌物产生并作用于寄主体壁。接种10h内,侵染性芽管通过顶端膨大的附着胞或直接穿透入寄主体壁。到24h时,产生侵染性芽管的孢子全部侵入寄主体内,寄主体表仅留下少数未萌发的孢子或营养生长型芽管。初级分生孢子在蚜体表面很少产生次级分生孢子,说明桃蚜是适合该菌侵染的寄主。陷入寄主体壁的孢子不因若蚜蜕皮而被去掉,表明该菌对成蚜和若蚜都具有侵染力。     

飞虱虫疠霉对褐飞虱的毒力(英文)

飞虱虫疠霉（Ｐａｎｄｏｒａ ｄｅｌｐｈａｃｉｓ（Ｈｏｒｉ） Ｈｕｍｂｅｒ）是我国稻区常见引发稻飞虱流行病的重要病原真菌。本研究用从稻飞虱虫尸上分离获得的两个飞虱虫疠霉菌株Ｆ９５１２７和Ｆ９５１２９分别对褐飞虱（Ｎｉｌｏｐａｒｖａｔａｌｕｇｅｎｓ Ｓｔａｌ）进行了毒力测定。将 ４－５龄若虫曝露在液体培养所获的产孢菌丝平板下进行“孢子浴”接种,通过控制孢子浴时间获得系列接种剂量。各剂量处理的若虫分别饲养于生长培养箱中,温度２５℃,光照１２Ｌ∶１２Ｄ,相对湿度接近饱和,逐日检查死亡数。所得数据很好地拟合时间－剂量－死亡率模型,由此获得用于估计毒力指标的时间和剂量效应参数。接种后 ６－８ ｄ, Ｆ９５１２９和 Ｆ９５１２７的 ＬＤ_（５０）分别为 ３２７、 １２２、４６孢子／ｍｍ~２和４０９、 １３３、 ７４孢子／ｍｍ~２, Ｆ９５１２７在９５孢子／ｍｍ~２剂量下的 ＬＴ_（５０）为７．６ｄ,而Ｆ９５１２９的ＬＴ_（５０）则从１７２孢子／ｍｍ~２时的 ６． ６ｄ下降到 ５２５孢子／ｍｍ~２时的５．６ｄ。根据所测毒力指标和剂量效应参数的分析比较,两个飞虱虫疠霉菌株对褐飞虱均具有中等毒力,且彼此间无显著差异。     

干燥与温度对飞虱虫疠霉凝胶化菌丝产孢特性的影响

The entomophthoraceous fungus, Pandora delphacis, is a microbial agent highly potential for control of sucking\|type insects.In this study,effort was made of gelatinizing the mycelia of the isolate F95129 from submerged culture using polyacrylamide\|starch gel pwder and sodium alginate.The resulting film\|like gel of the mycelia sporulated very well,indicating that the materials used for gelatinization of the mycelia was biologically compatible with P.delphacis. Then,the gelatinized mycelia were slowly dr…     

适合飞虱虫疠霉菌丝生产的液体培养基组分及发酵条件

蚜虫、飞虱、叶蝉等是威胁农业生产的刺吸式口器害虫,长期以来依赖化学农药防治,严重影响农产品的安全性和农业生态环境.探讨这类害虫的生物防治途径,减轻农产品化学农药的残留污染,一直受到国内外学者的关注.虫霉(En-tomophthorales)的许多种类具有优异的诱病杀虫能力,尤其通过主动弹射孢子而在害虫种群中高强度流行的特征,可在短期内迅速压低虫口密度,是极其重要的杀虫微生物资源[1～3].     

新蚜虫疠霉连续液体培养的菌丝生物量、产孢量及杀蚜毒力

继代培养常被疑为虫霉菌种毒力下降或某些生物学性状发生改变的原因之一。从研究新蚜虫疠霉 (Pandoraneoaphidis)固体平板菌落的液体培养获得的初始菌液出发 ,连续 6次继代液培 ,测定了其在萨氏营养液中继代培养生产的菌丝生物量、产孢量及其对桃蚜 (Myzuspersicae)的毒力。在初始菌液的生物量 8 8mg mL和产孢量 7 2× 1 0 5孢子 mg的条件下 ,以三种转接比 (种液 营养液 ,v v)连续 6次继代培养 ,在 1 2 0转接比下的菌丝生物量和产孢量分别为 6 4～ 1 0 0mg mL和 7 3× 1 0 5～ 1 0 8× 1 0 5孢子 mg,在 2 2 0下为 5 7～ 8 5mg mL和 1 0 0× 1 0 5～ 1 2 1× 1 0 5孢子 mg ,在 4 2 0下为 5 5～ 1 0 9mg mL和 6 4× 1 0 5～ 1 0 9× 1 0 5孢子 mg。方差分析表明 ,继代培养对生物量和产孢量均无显著影响 (P <0 0 5)。用初始菌液和 1 2 0转接比下继代培养的菌液制备而成的接种体对桃蚜进行两组毒力测定 ,每一组测定的接种…     

新型球孢白僵菌孢子悬乳剂的高效杀蚜活性及其评价方法

用球孢白僵菌（Beauveria bassiana）SG8702的孢子悬乳剂与未剂型化孢子粉对桃蚜进行了杀蚜活性对比测定。孢子悬乳剂与孢子粉分别用水稀释成5个序列浓度,对甘蓝叶片上蚜虫进行相同时间的弥雾接种,前者孢子附着量分别为1.5～701.1个孢子/mm2 ,后者附着量分别为2.8～1005.9个孢子/mm2。蚜虫接种后置于23℃和12L：12D条件下饲养,定时观察8d。经时间—剂量—死亡率模拟分析,悬乳剂的剂量效应参数明显高于孢子粉,且杀蚜时间效应提前。用模型参数估计悬乳剂和孢子粉的LC50,接种后第4天分别为9.0和634个孢子/mm2,第7天为3.3和5.3个孢子/mm2。悬乳剂和孢子粉的LT50随叶面孢子附着量增大而下降,在100个孢子/mm2下为3.2d和4.5d。这表明孢子悬乳剂的杀蚜活性比未剂型化的孢子粉显著增强。作者讨论了杀虫微生物制剂评价的技术规范问题。     

A proteomic approach to identifying proteins differentially expressed in conidia and mycelium of the entomopathogenic fungus Metarhizium acridum

Metarhizium spp. is an important worldwide group of entomopathogenic fungi used as an interesting alternative to chemical insecticides in programs of agricultural pest and disease vector control. Metarhizium conidia are important in fungal propagation and also are responsible for host infection. Despite their importance, several aspects of conidial biology, including their proteome, are still unknown. We have established conidial and mycelial proteome reference maps for Metarhizium acridum using two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF MS). In all, 1130±102 and 1200±97 protein spots were detected in ungerminated conidia and fast-growing mycelia, respectively. Comparison of the two protein-expression profiles reveled that only 35% of the protein spots were common to both developmental stages. Out of 94 2-DE protein spots (65 from conidia, 25 from mycelia and two common to both) analyzed using mass spectrometry, seven proteins from conidia, 15 from mycelia and one common to both stages were identified. The identified protein spots exclusive to conidia contained sequences similar to known fungal stress-protector proteins (such as heat shock proteins (HSP) and 6-phosphogluconate dehydrogenase) plus the fungal allergen Alt a 7, actin and the enzyme cobalamin-independent methionine synthase. The identified protein spots exclusive to mycelia included proteins involved in several cell housekeeping biological processes. Three proteins (HSP 90, 6-phosphogluconate dehydrogenase and allergen Alt a 7) were present in spots in conidial and mycelial gels, but they differed in their locations on the two gels.     

Production Factors Involved in the Formulation of Erynia neoaphidis as Alginate Granules

Granular formulations of the aphid-pathogenic fungus Erynia neoaphidis were produced by entrapping mycelia in alginate polysaccharide polymers. Four Swiss isolates were compared for the numbers of conidia discharged from the surface of alginate granules in standardized laboratory assays and two were considered to be suitable for further development. Conidiation was achieved from granules produced using nozzle diameters of 2.0. 1.0 and 0.5 mm from glass burettes or a novel vibrating tip apparatus. The mean diameters of dried granules varied from 0.5 to 1.8 mm. The addition of sucrose, potato starch or chitin in alginate solutions significantly improved the numbers of discharged conidia. W ith freshly produced granules, there was a 14.2- fold increase in sporulation from 6.3 to 89.7 conidia mm - 2 using 2% (w/v) sucrose. Increases of 1.6-to 2.3-fold, from 11.0 to 17.7 and 25.2 conidia mm - 2, were observed using 5% (w/v) starch or chitin respectively. The overnight drying of granules in a laminar flow hood and storage for 4 days at 4 C made differences in sporulation more obvious. There was a 15.5-fold difference in conidial numbers of 12.4 and 0.8 conidia mm - 2 from granules with and without sucrose respectively. For starch and chitin, there were 76.0-and 46.5-fold increases from 0.4 to 30.4 and 18.6 conidia mm - 2respectively. Fresh or dried alginate granules containing 2% sucrose and 5% starch gave 8.6-26.6% infection in laboratory bioassays with nymphs of pea aphid, Acyrthosiphon pisum , which were not significantly different when compared with infections of 6.7-22.9% using agar cultures or unsupplemented granules. Further studies on desiccation and storage regimes are required in order to improve the short-term shelf-life of E. neoaphidis alginate granules.     

Development of Powdery Mildew Fungi on Leaves Submerged Under Water

Effects of submerging inoculated leaves under water on the development of Erysiphe graminis f. sp. hordei on barley, E. pisi f. sp. pisi on pea and Sphaerotheca pannosa on rose were investigated. Submerging leaves immediately after inoculation removed 27–40% of conidia from leaves. Additionally, conidia either failed to germinate or germinated abnormally resulting in reduced elongating secondary hyphae (ESH) production. Submerging leaves 24 h after inoculation had, little effect on the numbers of ESH. Conidiophore production from mycelia occurred under water, although mildew growth was slower. Sporulating colonies treated with water produced conidia which had the ability to produce ESH. Experiments with E. aquilegiae on Aquilegia vulgaris, E. depressa on Arctium lappa, E. verbasci on Verbascum thapsus and Microsphaera alphitoides on Quercus rober suggest that the wettability of leaves and the presence of trichomes on leaf, surfaces play an important role in determining germination behaviour and subsequent ESH production on leaves.     

Nutrient Environments Influence Competition among Aspergillus flavus Genotypes

The population dynamics of Aspergillus flavus, shaped in part by intraspecific competition, influence the likelihood and severity of crop aflatoxin contamination. Competition for nutrients may be one factor modulating intraspecific interactions, but the influences of specific types and concentrations of nutrients on competition between genotypes of A. flavus have not been investigated. Competition between paired A. flavus isolates on agar media was affected by varying concentrations of carbon (sucrose or asparagine) and nitrogen (nitrate or asparagine). Cocultivated isolate percentages from conidia and agar-embedded mycelia were quantified by measurements of isolate-specific single-nucleotide polymorphisms with quantitative pyrosequencing. Compositions and concentrations of nutrients influenced conidiation resulting from cocultivation, but the percentages of total conidia from each competing isolate were not predicted by sporulation of isolates grown individually. Success during sporulation did not reflect the outcomes of competition during mycelial growth, and the extents to which isolate percentages from conidia and mycelia differed varied among both isolate pairs and media. Whether varying concentrations of sucrose, nitrate, or asparagine increased, decreased, or had no influence on competitive ability was isolate dependent. Different responses of A. flavus isolates to nutrient variability suggest genotypes are adapted to different nutrient environments that have the potential to influence A. flavus population structure and the epidemiology of aflatoxin contamination.     

Virus Particles from Conidia of Penicillium Species

Virus particles and their component double-stranded ribonucleic acid (dsRNA) have been isolated from conidia and mycelia of certain Penicillium species. The conidia and mycelia of P. stoloniferum NRRL 5267 contained 75 and 85 mug of dsRNA/g (dry weight), respectively. Of the total dsRNA released from NRRL 5267 conidia, 10% was nonencapsulated. Conidia of P. brevi-compactum NRRL 5260 and P. chrysogenum Q-176 contained 2 and 120 mug of dsRNA/g (dry weight), respectively, whereas mycelium from the two species contained 3 and 95 mug of dsRNA/g (dry weight), respectively. No viruses were isolated from conidia or mycelia of P. stoloniferum NRRL 859. A method is described for disruption of both conidia and mycelia. The technique facilitates the isolation and characterization of fungal viruses and their component dsRNA and also potentiates surveying of fungal isolates for the presence of virus.     

Culture medium improvement for Isaria fumosorosea submerged conidia production

Submerged conidia and blastospores of the entomopathogenic fungus Isaria fumosorosea are produced in several liquid culture media. However, yields and the ecological fitness of these propagules vary according to culture media composition. In most culture media, hyphae, blastospores and submerged conidia are white but we found that in some media they develop a brown pigmentation. A dark pigment was extracted from brown-pigmented propagules and analyzed by IR spectroscopy. Adsorption bands coincided to those characteristics of melanins.Hadamard's matrices were employed in order to increase submerged conidia yields and brown pigmentation of fungal propagules. Media containing 20–30 mg/l of FeSO₄·7H₂O and 6–12 mg/l of CuSO₄·5H₂O allowed reaching the highest pigmentation (9 in a hedonic scale). A maximal concentration of submerged conidia of 1.0 (±1.2) × 10¹² cell/l was achieved after 120 h of liquid culture in a improved culture medium, containing 25 ml/l of Polyethylene glycol (MW 200), substance which enhanced submerged conidia production, reducing free mycelia or mycelial pellets formation. In the improved medium, it was estimated that more than 60% of produced biomass corresponded to submerged conidia and blastospores, while in other media, mycelia were the main product (80–97%).