The microbial diversity and structure in peatland forest in Indonesia

The microbial community structure and function under forest in tropical peatlands are poorly understood. In this study, we investigated the microbial community structure and diversity in natural peat swamp forest soil, disturbed peat soil and mineral soil in Central Kalimantan, Indonesia, using 454 pyrosequencing. The results showed that the natural peat soil had the greatest fungal species richness (Chao1), which was significantly (p < .05) larger than that in the other two soils. Community structure of both fungi and bacteria in natural peat soil differed significantly from that in the disturbed peat soil (p = .039 and p = .045, respectively). Ascomycota (40.5%) was the most abundant phylum across the three soils followed by Basidiomycota (18.8%), Zygomycota (<0.1%) and Glomeromycota (<0.1%). The linear discriminant analysis with effect size (LEfSe) showed that Ascomycota (p < .05) and genus Gliocephalotrichum (p < .05) dominated in natural peat soil. Functionally, pathotrophs were more abundant in disturbed peat soil (p < .05). Proteobacteria (43.8%) were the most abundant phylum followed by Acidobacteria (32.6%), Actinobacteria (9.8%), Planctomycetes (1.7%). Methylocystis, Telmatospirillum, Syntrophobacter, Sorangium and Opitutus were the more abundant genera in disturbed peat soil, whereas Nevskia and Schlesneria were more abundant in mineral soil and natural peat soil, respectively. The natural peat forest soil supported a more diverse microbiology; however, the land use of such a soil can change its microbial community structure. The results provide evidence that the disturbance of tropical peat land could lead to the introduction and spread of a large number of fungal diseases     

Biological control of the Western flower thripsFrankliniella occidentalis in cucumber using the entomopathogenic fungusMetarhizium anisopliae

Biological control of the western flower thrips (WFT)Frankliniella occidentalis, using the entomopathogenicMetarhizium anisopliae-7 (M. a-7) strain was studied in three consecutive seasons under greenhouse conditions. Cucumber plants infested with WFT were sprayed with spore suspension of the fungusM. a-7 (0.5 g m^-2), or the soil was treated with dry powder of the fungus (0.5 g m^-2); the control was without fungus application. In the 1997 spring experiment, when the cucumber plants were initially infested with only three or four insects per leaf, the spore suspension spray caused a significant reduction in growth of the thrips population compared with the other treatments and the control. However, in the 1997 summer experiment, when the plants were initially heavily infested with WFT (10–15 insects per leaf), the spray treatment caused only a modest reduction in WFT population growth, and only after 4 weeks of treatment was the reduction significant. In the 1999 experiment, with a low initial WFT population of three or four insects per leaf, the spray treatment was effective in reducing the population growth to a lower level than in the other treatments or control. TheM. a-7 strain was found to be effective in reducing the population growth of WFT under greenhouse conditions, particularly when the initial thrips population was low to moderate. http://www.phytoparasitica.org posting Nov. 4, 2001.     

昆虫病原线虫和共生细菌培养系统中噬菌体的检测

本文利用紫外照射、温度、pH、盐度诱导五株溶源性共生菌株Xenorhabdus和Photorhabdus同时测定斯氏和异小杆属线虫Steinernema carpocapsae A24,S.carpacapsae ALL,S.feltiae English,S.feltiae SN,Heterorhabditis bacterophora H06在体外培养过程中是否存在感染共生细菌的噬菌体。结果未发现噬菌斑，说明实验菌株在实验诱导条件下以及昆虫病原线虫固体培养系统中不可能诱发噬菌体的危害。     

Effect of cyclodextrin diallyl maleate on methane production, ruminal fermentation and microbes in vitro and in vivo

Effects of β‐cyclodextrin diallyl maleate (CD‐M) on methane production, ruminal fermentation and digestibility were studied both in vitro and in vivo. In in vitro study, diluted ruminal fluid (30 mL) was incubated anaerobically at 38°C for 6 and 24 h with or without CD‐M using hay plus concentrate (1.5:1) as a substrate. The CD‐M was added at different concentrations (0, 1.25, 2.5, 5.0 and 7.5 g/L). The pH of the medium and numbers of protozoa were not affected by the addition of CD‐M. Total volatile fatty acids were increased and ammonia‐N was decreased, molar proportion of acetate was decreased and propionate was increased (P < 0.05) by CD‐M. Methane was inhibited (P < 0.05) by 14–76%. The effect of CD‐M on methane production and ruminal fermentation was further investigated in vivo using four Holstein steers in a cross‐over design. The steers were fed Sudangrass hay and concentrate mixture (1.5:1) with or without CD‐M (2% of feed dry matter) as a supplement. Ruminal proportion of acetate tended to decrease and that of propionate was increased (P < 0.05) 2 h after CD‐M dosing. Total viable counts, cellulolytic, sulfate reducing, acetogenic bacteria and protozoa were unaffected while methanogenic bacteria were decreased (P < 0.05) by CD‐M. The plasma concentration of glucose was increased, whereas that of urea‐N was decreased (P < 0.05). Methane was inhibited (P < 0.05) from 36.4 to 30.1 L/kg dry matter intake by the addition of CD‐M. Apparent digestibilities of dry matter and neutral detergent fiber were not affected while that of crude protein was increased (P < 0.05) in the medicated steers. These data suggested that dietary supplementation of CD‐M decreased methane production and improved nutrient use.     

人工养殖西伯利亚狍肠道微生物组成的雌雄差异

肠道微生物是一个复杂的生态系统,与宿主的健康、疾病以及其他因素有着密切的关系。目前,关于肠道菌群结构和功能的研究较多,但是对西伯利亚狍肠道菌群的研究还未见报道。西伯利亚狍(Capreolus pygargus)属于反刍动物,有独特的消化特性和微生物群来帮助它们适应高纤维的食物。本研究利用高通量测序技术在Illumina MiSeq平台上对14只狍肠道微生物进行16S rRNA基因分析。结果表明:个体样本中门类组成的差异,雌性个体JY3和雄性个体JY9除Firmicutes,Bacteroidetes,Proteobacteria这3类菌群外,其他门类菌群所占比例都很低。在科水平上,雌性个体中Ruminococcaceae在JY7和JY13肠道内含量相对较少,Bacteroidaceae在JY7,JY10和JY13中含量较高。雄性个体中Ruminococcaceae在JY11和JY14肠道内含量较少,Prevotellaceae在JY4中含量较少。在属水平上,雌性个体特有的菌属为Roseburia,Alloprevotella,Lachnospiraceae_incertae_sedis和Coprococcus;雄性个体特有的菌属为Fusobacterium,Succiniclasticum,Streptococcus和Clostridium sensu stricto。Alpha多样性分析表明,Ace指数范围2128.93—772.98,Chao1指数范围2128.89—785.27,Shannon指数范围5.44—3.78,Simpson指数范围0.07—0.01。在不同物种分类水平上,雌雄狍肠道内的优势菌群有些不同。PCoA(principal co-ordinates analysis)分析显示,狍样本几乎混在一起,没有明显差异。     

昆虫病原线虫生物防控草地贪夜蛾的室内及田间效果和影响因素

联合国粮食及农业组织2018年向全球发布草地贪夜蛾Spodoptera frugiperda是重要的预警害虫。据报道,2019年我国已有26个省（区、市）的作物受到草地贪夜蛾为害。目前已经发现草地贪夜蛾幼虫对某些化学农药产生抗性的现象,为缓解其抗药性产生,具有主动寻找寄主害虫的昆虫病原线虫为草地贪夜蛾的生物防治提供了应用潜能。该文从昆虫病原线虫高效侵染种（品系）及其浓度、共生菌、草地贪夜蛾幼虫易感龄期、田间致死力及影响防控效果的因素等方面进行综述,以期为田间有效利用昆虫病原线虫防治草地贪夜蛾提供参考。     

昆虫病原真菌在害虫防治中对天敌生物的影响研究进展

昆虫病原真菌是一类重要的微生物杀虫剂,广泛应用于农林害虫的生物防治。由于寄主范围广和主动侵染的特点,昆虫病原真菌在侵染、致死靶标害虫的同时,对包括天敌昆虫在内的非靶标节肢动物等会产生潜在的致病或亚致死风险。本文总结了昆虫病原真菌在害虫防治中的研究进展及对天敌生物的影响,并展望了昆虫病原真菌作为极具潜力的生物农药与天敌生物联合防治害虫的未来发展方向。     

小卷蛾斯氏线虫对辣椒烟粉虱的控制作用

本文研究了小卷蛾斯氏线虫Steinernema carpocapsae对烟粉虱Bemisia tabaci的侵染能力以及对田间辣椒烟粉虱的控制作用.结果表明,室温(28±2)℃,空气湿度(60±5)％,辣椒叶背面湿润的条件下,线虫约在4 h侵入烟粉虱若虫体内,2～3 d内致其死亡.不同浓度线虫对烟粉虱若虫的控制效果不同...     

保护性耕作对土壤团聚体、微生物及线虫群落的影响研究进展

保护性耕作具有良好的生态效益,有利于农业生态系统的可持续发展。本文对比分析了国内外有关常规耕作和保护性耕作措施对土壤团聚体、土壤有机碳、土壤微生物及土壤线虫影响的研究进展。结果表明：保护性耕作减少土壤大团聚体的破坏,降低团聚体周转速率,提高土壤结构的稳定性;保护性耕作提高表层土壤总有机碳及活性有机碳含量;保护性耕作可以提高耕层微生物生物量,尤其对真菌生物量影响显著;保护性耕作不同程度地提高了团聚体中微生物量和微生物多样性,但并未改变微生物在团聚体中的分布模式;保护性耕作可提高土壤线虫多度,提高原状土壤和土壤各粒级团聚体中线虫群落的成熟度指数和结构指数,但并未改变线虫总数、营养类群、功能团及生态指数在团聚体中的分布模式。针对目前国内外研究现状,展望了保护性耕作今后的研究重点,以期为因地制宜选取保护性耕作措施提供理论支持,推进我国农业可持续发展。     

黄河下游滩地杨树人工林土壤微生物分析

对山东省济南市长清区黄河下游滩地杨树人工林林地土壤微生物数量及分布特征进行了分析,结果表明:滩地杨树人工林土壤微生物主要分布在0～20cm的土层,20～50cm土层的微生物较少;各林地土壤微生物数量明显高于新淤地微生物数量;细菌是滩地杨树人工林林地土壤微生物的主要组成成分,在上、下层土壤中所占比例分别为81.7%～99.1%和75.1%～98.8%;土壤微生物数量随林龄的增长呈现高—低—高的变化趋势,但至林木主伐前,固氮菌和纤维素分解菌数量有所降低;不同管理模式影响微生物的数量,集约经营管理的林分土壤微生物数量较多;滩地杨树人工林土壤微生物数量与土壤颗粒组成密切相关。