辣椒镰孢根腐病防病促生细菌的筛选及其效应

【目的】筛选辣椒(Capsicum annuum L.)根腐病防病促生细菌并明确其防病促生效应。【方法】采集健康辣椒根围土壤样品,以辣椒根腐病病原真菌茄镰孢(Fusarium solani)和尖镰孢(Fusarium oxysporum)为指示菌,采用平板对峙法筛选生防细菌,采用选择性培养基筛选溶无机磷、溶有机磷、固氮菌和解钾菌等促生菌,钼锑抗比色法测定溶磷量,凯氏定氮法测定固氮量,火焰原子吸收光谱法测定解钾量。对特性良好组合的菌株进行16S rDNA序列分析鉴定并制作菌剂,最后采用盆栽法测定菌剂防病促生效果。【结果】共筛选得到323株特性良好的功能菌株,拮抗菌78株,溶有机磷菌87株,溶无机磷菌107株,固氮菌128株,解钾菌123株,部分菌株同时具有多个功能特性。互作组合得到6个特性良好的菌株组合,包括8株功能菌株,鉴定发现XP271和XP181为枯草芽胞杆菌(Bacillus subtilis),XP125为特基拉芽胞杆菌(Bacillus tequilensis),XP236为耐盐芽胞杆菌(Bacillus halotolerans),XP79为巨大芽胞杆菌(Bacillus ...     

沙棘根瘤内生细菌中抑菌促生菌株的筛选和鉴定

【背景】植物内生细菌可产生具有抑菌和促生活性的物质,既能抑制植物病原菌对寄主植物的侵染,也能促进植物的生长。沙棘根瘤内生细菌是根瘤内除共生固氮的弗兰克氏菌外,与沙棘共生的一大类微生物。研究具有抑菌和促生活性的植物内生菌,可为微生物菌肥的研究提供理论基础。【目的】筛选具有优良抑菌和促生活性的沙棘根瘤内生细菌,初步研究其抑菌和促生活性,并对菌株进行鉴定。【方法】采用双层琼脂法、琼脂扩散法、双层平板对峙法、牛津杯法进行沙棘根瘤拮抗性内生细菌的筛选。选取抑菌活性较高的内生细菌,分别采用Salkowski比色法、ChromeAzurolS(CAS)平板检测法和钼锑抗比色法进行产吲哚乙酸、铁载体及溶磷能力的测定。采用发酵液灌根法测定沙棘根瘤内生细菌SR308对黄瓜促生作用的盆栽效果。通过形态和培养特征、生理生化试验及16S rRNA基因序列分析法对菌株TT201和SR308进行鉴定。【结果】从131株沙棘根瘤内生细菌中筛选出9株具有较强抑菌活性的内生细菌,其中菌株TT201抑菌性最佳、抑菌谱广;菌株SR308的促生活性最好,其发酵液对黄瓜的生长具有较强的促进作用。对具有较强抑菌和促生活性的菌株TT201和SR308进行鉴定的结果表明,菌株TT201为侧孢短芽孢杆菌(Brevibacilluslaterosporus),菌株SR308为蕈状芽孢杆菌(Bacillusmycoides)。【结论】获得2株具有优良抑菌和促生活性的沙棘根瘤内生细菌,为进一步开发微生物农药及菌肥提供了资源。     

西葫芦根腐病菌拮抗细菌的防病促生作用

【目的】获取促生的同时可抑制尖孢镰刀菌(Fusarium oxysporum)的拮抗菌并明确其防治效果。【方法】平板对峙生长法测定前期分离的19株促生菌对尖孢镰刀菌的抑制作用,温室条件下接种微生物菌剂对西葫芦根腐病的防治作用;田间条件下接种复合菌剂代替部分化肥对西葫芦生长的影响。【结果】可有效拮抗尖孢镰刀菌的菌株有9株,其中,菌株FX2的抑菌活性较好,抑制率达到66.80%。在温室盆栽中,接种微生物菌剂(LHS11+FX2)对西葫芦根腐病抑制率达到57.14%。在田间试验中,微生物菌剂配施化肥对西葫芦的生物量和根系形态影响显著,以85%化肥+复合菌剂处理效果较优,其对西葫芦成熟期的产量显著提高27.13%。【结论】复合菌剂(LHS11+FX2)对西葫芦根腐病具有较好的防治作用;85%化肥+复合菌剂对西葫芦的促生作用明显,在一定程度上节约了化肥投入成本,提高了增产效益。     

解淀粉芽胞杆菌PHODB35的溶磷特性及其对番茄的促生作用

【目的】从种植番茄的根围土壤中筛选高效溶磷细菌,为减施化学肥料和开发微生物肥料提供溶磷菌种资源,并初步探索其促生机制。【方法】采用无机磷培养基利用梯度稀释涂布法从土壤中分离筛选促生菌株,通过形态特征、16S rRNA和gyrB基因序列分析对优良促生菌株进行鉴定,并分别利用正交试验和单因素试验分析环境因子和营养因子对其溶磷效果的影响,进一步利用HPLC-MS并结合相应有机酸的标准物质,明确优良促生菌株产生的有机酸种类;盆栽试验测定接菌处理后番茄株高、地上鲜重、地下鲜重、基质和植株有效磷含量评价菌株对番茄的促生作用。【结果】筛选到1株优良的促生菌株,命名为PHODB35,鉴定其为解淀粉芽胞杆菌(Bacillus amyloliquefaciens)。对环境因子的正交试验结果表明,菌株PHODB35最佳溶磷条件为pH 7.0,温度为30°C,接种量为5%;对营养因子的单因素试验结果表明,该菌株以葡萄糖为碳源、硫酸铵为氮源、磷酸钙为磷源时,解磷效果最好,有效磷浓度为88.77mg/L。明确了菌株PHODB35产生的有机酸为葡萄糖酸。盆栽实验结果表明,菌株PHODB35对番茄幼苗有明显的促生作用,与空白对照相比,施用菌株后对株高、地上鲜重、地下鲜重、基质和植株有效磷含量分别增加28.21%、22.59%、113.06%、45.08%和16.24%,表明菌株PHODB35具有一定的肥效功能,可用于促生菌剂的研制。【结论】筛选到具有促生能力的解磷细菌,为进一步开发研制番茄促生菌剂或微生物有机肥提供资源,为菌株PHODB35在农业生产中的应用提供了理论依据和实验基础。     

水稻内生固氮菌Herbaspirillum seropedicae DX35的筛选及其促生特性

摘要:【目的】筛选水稻高效内生固氮菌,并对其促生特性进行分析。【方法】从湖南祁阳中国农业科学院红壤实验站具30年长期稻-稻-绿肥轮作定位试验田中采集水稻根并分离内生细菌,通过乙炔还原法测定其固氮酶活性,筛选出固氮活性较高的菌株,运用16S rRNA基因、nifH基因以及脂肪酸分析确定其发育地位。同时采用Salkowski比色法测定其生长素的分泌能力,CAS蓝色平板检测法测定产铁载体能力,溶磷圈法测定溶磷性,对其促生特性进行分析。【结果】共分离获得48株内生菌,其中DX35固氮酶活性最高,经鉴定属于Herbaspirillum seropedicae,其固氮酶活性为181.21 nmol C2H4/(mg protein·h),约是参比菌株Azotobacter chroococcum ACCC10006的10倍。另外该菌株还具有一定的分泌铁载体能力和溶磷特性。【结论】DX35属于H.seropedicae,是一种高效内生固氮菌,具有很好的生产应用前景。     

水稻内生固氮菌Herbaspirillum seropedicae DX35的筛选及其促生特性

【目的】筛选水稻高效内生固氮菌,并对其促生特性进行分析。【方法】从湖南祁阳中国农业科学院红壤实验站具30年长期稻-稻-绿肥轮作定位试验田中采集水稻根并分离内生细菌,通过乙炔还原法测定其固氮酶活性,筛选出固氮活性较高的菌株,运用16S rRNA基因、nifH基因以及脂肪酸分析确定其发育地位。同时采用Salkowski比色法测定其生长素的分泌能力,CAS蓝色平板检测法测定产铁载体能力,溶磷圈法测定溶磷性,对其促生特性进行分析。【结果】共分离获得48株内生菌,其中DX35固氮酶活性最高,经鉴定属于Herbaspirillum seropedicae,其固氮酶活性为181.21 nmol C2H4/(mg protein·h),约是参比菌株Azotobacter chroococcum ACCC10006的10倍。另外该菌株还具有一定的分泌铁载体能力和溶磷特性。【结论】DX35属于H.seropedicae,是一种高效内生固氮菌,具有很好的生产应用前景。     

玉米根际高效溶磷菌的筛选、鉴定及促生效应研究

为获得玉米根际高效溶磷促生菌(Plant growth-promoting rhizobacteria,PGPR)并明确其促生特性,采用选择培养方法从玉米根际土壤筛选出优良PGPR 菌株,测定其溶磷及分泌吲哚乙酸(IAA)的能力,并对优良菌株进行鉴定;采用盆栽试验研究菌株的促生作用。结果分离到2 株优良PGPR 菌株CH07和FD11,其溶磷量分别为368.5 mg/L和321.5 mg/L,产IAA量分别为30.93 mg/L和15.93 mg/L。形态学特征、生理生化特征和16S rDNA 序列分析结果表明,CH07为芽孢杆菌属(Bacillus aryabhattai),FD11为链霉菌属(Streptomyces maritimus)。最后通过盆栽试验对这2株细菌分离物的促生效果进行比较,结果发现,CH07、FD11,尤其是CH07与FD11的复合物,对苋菜的株高及地上部鲜重有积极作用,可作为研制生物肥料的优良菌株资源。     

苎麻促生菌的筛选、鉴定及其促生效应

【目的】以苎麻(Boehmeria nivea L. Gaud)根及根围土壤为研究材料,进行苎麻促生菌的筛选,并初步探索其促生作用机制。【方法】首先,以溶磷和解钾为基本筛选标准,初筛菌株在实验室条件下测定多项促生能力进行复筛;然后通过种子萌发、盆栽试验测定菌株对苎麻的促生效应,最后,通过形态观察、生理生化特性和16S rRNA基因序列同源性分析,对促生菌株进行分类学鉴定。【结果】从苎麻根和根围土壤中分离得到了13株菌同时具备溶磷和解钾能力,其中4株菌(RA-2、RAM-2、RAM-5和RAM-6)具备产铁载体、产IAA和产氨能力。种子萌发和盆栽试验的测定结果显示：4株菌株均能促进苎麻种子的萌发和植株的生长,其中菌株RA-2和RAM-5相比于对照处理能显著提高苎麻种子的萌发率、幼根长、株高和根系干重。分类鉴定结果显示菌株RA-2和RAM-5均属于伯克霍德菌属(Burkholderia)。【结论】从苎麻根围筛选到具有促生能力的菌株,为进一步开发研制苎麻专型促生菌剂或专型微生物有机肥提供资源。     

东乡野生稻内生细菌Fse32拮抗作物病害真菌及对水稻的促生活性

【背景】植物种子是植物内生菌筛选的重要原料,从中能够分离得到具有巨大应用价值的内生菌株。【目的】为发掘优良的种子内生细菌资源,对分离自东乡野生稻种子的内生细菌Fse32进行鉴定并研究其抗病原真菌和促生活性。【方法】通过形态学观察、生理生化特征和16SrRNA基因序列分析进行菌种鉴定,采用拮抗试验检测抑制病原真菌的活性,通过促生能力测定试验、水稻种子萌发及盆栽试验评价该菌株的促生效果。【结果】内生细菌Fse32鉴定为唐菖蒲伯克霍尔德氏菌,命名为Burkholderia gladioli Fse32。拮抗试验结果显示,菌株Fse32对禾谷镰孢菌(Fusarium graminearum)、水稻纹枯病菌(Rhizoctoniasolani)、核盘菌(Sclerotiniasclerotiorum)、大豆核盘菌(Sclerotinialibertiana)、尖孢镰刀菌(Fusariumoxysporum)和辣椒疫霉病菌(Phytophthoracapsici)均有较好的抑制作用,吲哚乙酸(indole-3-aceticacid,IAA)产率为17.95mg/L,能产铁载体,其A/Ar比值为0....     

岑溪药用野生稻高效内生固氮菌分离及促生特性

【目的】以广西岑溪市野生稻保护区的药用野生稻为材料,分离纯化内生细菌,筛选固氮酶活性较高和对作物促生效果较好的菌株。【方法】利用乙炔还原法检测固氮酶活性,采用SDS-PAGE全细胞蛋白电泳和IS-PCR指纹图谱技术对分离到的固氮菌进行聚类。利用16S rRNA基因和nifH基因确定其系统发育地位。采用钼锑抗比色法、Salkowski比色法和CAS检测法分别测定菌株溶磷性、生长素的分泌能力和产铁载体能力。通过平板和盆栽试验检测其对水稻的促生作用。【结果】共分离得到35株内生固氮菌,分为6个类群。其中CX24固氮酶活性最高,经鉴定属于Klebsiella variicola,其固氮酶活性为298.64 μmol/(L·h),为参比模式菌株DSM15968的9倍。另外该菌株还具有较高的溶磷性、分泌生长素和产铁载体能力,能够有效地促进水稻的萌发和生长。【结论】菌株CX24属于Klebsiella variicola,是一株高效内生固氮菌,具有很好的生产应用前景。     

After biocontrol: Assessing indirect effects of insect releases

Development of biological control agents for weeds has been motivated by the need to reduce the abundance and distribution of a pest plant where chemical and mechanical control were not cost effective. Primary objectives have been direct reduction in abundance of the target and, secondarily, the increase of desirable species. Recently, wildland weeds have become a focus of biological control projects. Here, desired outcomes include both reduction of the target and indirect effects of increased diversity and abundance of native species and restoration of ecosystem services. However, goals and benefits of biocontrol programs are not always well-articulated and direct and indirect impacts are not easily predicted. We evaluated the extent to which several successful biological control projects for weeds of rangelands and waterways measured indirect impacts on invaded ecosystems. We also examined biocontrol of a wildland pest tree for which the principal objective is restoration of ecosystem services. We found few quantitative assessments of the impacts of pest plant reduction on community composition or ecosystem processes. All examples documented variation in the impacts of agent(s) across the invasive range of the target plant as well as variation in impacts on the invaded ecosystem. However, without appropriate quantitative information, we cannot evaluate site characteristics that may influence vegetation responses. Most successful weed management programs integrated the use of biocontrol agents with other weed management strategies, especially modifications of disturbance and competing vegetation. Discussion and evaluation of responses of nontarget species would improve our understanding of the context-specificity of outcomes.     

Thermal effects on the egg stage of four sciomyzids with reference to phenology and biocontrol potential

Abstract:  With the global economic cost of liver fluke estimated at US$2000 million annually, alternative sustainable control methods need to be considered. One such option is biological control using malacophagous sciomyzids (Dipt.,). The effect of a range of temperatures (14, 17, 20, 23 and 26°C) on the duration of the egg stage of Sepedon spinipes spinipes (Scopoli), Pherbina coryleti (Scopoli), Tetanocera ferruginea Fallén and Psacadina verbekei Rozkošný was assessed using thermostatically controlled waterbaths (16 h light : 8 h dark). In general, for all species, the mean and median egg incubation periods decreased as the temperature increased. Optimum growth temperatures for mass rearing purposes are highlighted for each species. The cryopreservation (−20°C) of newly oviposited eggs for the purpose of long-term storage was also assessed and possible reasons for the variability in the duration of the egg stage between the species in relation to their phenologies are discussed.     

Towards the biocontrol of bindweeds with a mycoherbicide

Within the framework of the European COST Action 816, afive-year collaboration between scientists from five Europeancountries has made an important contribution to biologicalcontrol of field and hedge bindweeds (Convolvulus arvensis andCalystegia sepium, respectively). A fungus Stagonosporaconvolvuli strain LA39, able to infect both field and hedgebindweed, was found in the UK and its biocontrol efficacyimproved by optimising mass production, formulation and storagetechniques. This fungus controlled bindweeds in both a cemeteryand in maize crops. Its use fits best in an integrated pestmanagement system where a green cover controls most of the weedsexcept the bindweeds. DNA marker analyses indicate that thefungus reproduces sexually, which could be used to furtherimprove this mycoherbicide. In addition, the insect Melanagromyzaalbocilia, which itself exhibits biocontrol potential againstbindweeds, may be used in combination with LA39 to improve theability of the fungus to penetrate the stem of bindweeds.Overall, the results suggest that S. convolvuli LA39 haspromising potential as a bioherbicide for control of field andhedge bindweed.     

Thermal ecology of Zonocerus variegatus and its effects on biocontrol using pathogens

1 Thermal behaviour of the variegated grasshopper, Zonocerus variegatus, was investigated in the humid tropical zone of southern Benin, west Africa, in the dry seasons of 1996 and 1998. In 1998, investigations included studies of a population of grasshoppers sprayed with an oil‐based formulation of the entomopathogenic fungus Metarhizium anisopliae var acridum. 2 Body temperature measurements and observations of thermal behaviour both in the field and on thermal gradients in the laboratory, suggest that Z. variegatus was not an active behavioural thermoregulator. Although it did show shade‐seeking behaviour at high temperatures, no overt behavioural postures or microhabitat selection associated with heat gain and elevation of body temperatures was observed. Moreover, no alterations to thermal behaviour were found in response to infection by Metarhizium. 3 Body temperatures exhibited by Z. variegatus in the field will lengthen disease incubation of M. anisopliae var acridum compared with laboratory maintained, constant temperature conditions and may have a significant impact on pathogens with a lower thermal tolerance. 4 Habitat structure appeared to be an important factor determining the extent of body temperature elevation. The effect of habitat differences on infection and growth of M. anisopliae var acridum and other entomopathogenic fungi is discussed.     

Modelling biocontrol of

The two haplotypes of Varroa destructor that have been identified as parasites of the Western honeybee (Apis mellifera L.) show disparate levels of virulence towards honeybee colonies. The Korea haplotype has been associated with severe colony mortality, whereas untreated colonies of European A. mellifera have survived long-term infestation by the Japan haplotype. The possible existence of a benign haplotype of V. destructor raises the prospect that it be used to “inoculate” colonies to provide biocontrol of the virulent haplotype. The feasibility of such a strategy was investigated using a mathematical model. Competition for resources during reproduction is known to reduce varroa mites’ reproduction rates as their infestation levels increase. Results from modelling suggested this density-dependent effect is sufficient for an established benign population to prevent the virulent population reaching destructive levels if a colony is subject to sporadic influxes of virulent mites. A colony faced with a continuous influx of mites could be protected if the proportion of virulent mites in the influx were below a threshold level (dependent on length of breeding season and intensity of influx). This condition might be achieved by “inoculating” neighbouring apiaries and controlling feral colonies in the vicinity. Decreased brood cell invasion rate by the benign haplotype decreased the threshold level. Any reproductive isolation between the benign and virulent haplotypes would cause further reproductive suppression, driving sporadic influxes of the virulent haplotype to extinction and conferring greater tolerance to a colony faced with a virulent influx. Increased colony resistance to varroa in the model was synergistic with the inoculation of colonies in the absence of reproductive isolation, but potentially antagonistic in its presence—although not to an extent that would preclude their joint use.     

外来入侵杂草的生物防治及生防因子对本地非目标种的影响

随着生物入侵所引起的生态及经济问题日益严重,对有害入侵生物的防治问题也备受人们关注。生物防治因具有持续、高效、安全等优点,已成为防治有害入侵生物的重要方法。传统生防是防治有害入侵杂草的一种重要方法。在简单介绍生物防治的基础上,重点阐述了传统生物防治的理论基础——天敌逃逸假说,生防因子对外来人侵种的影响及其对本地非目标种的直接和间接效应,并针对这些问题,对我国开展生物防治工作提出几点建议。     

Intraguild interference and biocontrol effects of generalist predators in a winter wheat field

Arable land typically harbours communities of polyphagous invertebrate natural enemies, among them numerous soil-surface dwelling predators such as ground beetles (Carabidae) and spiders (Lycosidae, Linyphiidae). Numbers of these predators were experimentally manipulated in a winter wheat field in order to study the predation impact of a generalist predator assemblage on herbivorous insects, the possible interferences among the predators concerned, and subsequent effects on wheat plant parameters. Removing ground beetles doubled numbers of Lycosidae indicative of intraguild interference between these two predator groups. Aphid densities were highest in carabid removal plots implying a substantial predation impact of ground beetles on the pest population. The predation impact of ground beetles was strongest earlier and disappeared later in the season. In mid-season, at intermediate aphid densities, the combined impact of carabid beetles and spiders appeared to be responsible for the reduction in aphid abundance. This result was probably due to a biomass effect rather than to a synergistic effect of the predator community. Thysanoptera decreased when spiders were removed (perhaps because spiders were preying on a predator of thrips), while Cicadellidae and Delphacidae showed no effect at all. The rise of aphid numbers in carabid removal plots corresponded to an increase in protein content of the wheat grains, while other plant parameters such as plant numbers and grain mass were not affected. In conclusion, this study provided field evidence for intraguild interference among generalist ground predators in arable land. Despite this interference the polyphagous predator community was able to depress numbers of aphids in winter wheat, a result cascading down to plant quality parameters.     

Use of disease progress curves to study the effects of the biocontrol agent Sporidesmium sclerotivorum on lettuce drop

At the end of the spring 1987 growing season, the mycoparasite Sporidesmium sclerotivorum was applied at 0, 0.2, 2 or 20 kg ha^‐1 to lettuce plants infected with Sclerotinia minor. Disease incidence was monitored in the same plots for five subsequent crops (three fall and two spring crops) without additional application of either pathogen or mycoparasite. Logistic growth curves were fitted to the data to describe disease progression over time for each inoculum level within each of the five crops. Within each crop, increasing the quantity of mycoparasite inoculum resulted in positive horizontal displacement of the curve with respect to time. As quantities of inoculum of S. sclerotivorum increased, inflection points of the disease progress curves increased at a decreasing rate. Thus, additional mycoparasite inoculum resulted in ever‐smaller increases in inflection point, and after a certain threshold level of mycoparasite inoculum (< 0.2 kg ha^‐1), increases in inflection point did not result in meaningful increases in harvestable lettuce. Maximum rates of disease increase were not different among the treatments within each crop, but were different between crops. Maximum rates of disease increase averaged 3.4, 3.4, 2.1, 3.6 and 1.5% day^‐1 for the fall 1987, spring 1988, fall 1988, spring 1989, and fall 1989, respectively. At all inoculum levels, the fall epidemics began later after planting than the spring epidemics.