无纺布白僵菌条防治萧氏松茎象试验

2010-2011年在信丰林区开展了无纺布白僵菌条防治萧氏松茎象成虫试验。结果表明,2010．2011年试验区萧氏松茎象当年肴虫株率平均分别下降71．2％和76．7％;相对防治效果平均分别为75．0％和78．9％。这说明无纺布白僵菌条能明显抑制萧氏松茎象种群的上升。     

花绒寄甲人工繁育及应用研究

为解决花绒寄甲人工繁育技术的关键问题,进一步提高产量,开展了低温保存对花绒寄甲卵活力的影响、替代寄主选择、成虫人工饲料配方、室内生活史等研究,并在后期初步开展了花绒寄甲对桃红颈天牛的野外防效试验。结果表明,4℃条件下保存0～60 d对花绒寄甲卵孵化率的影响存在显著差异,不经低温处理的卵孵化率最高,可达70.87%,低温保存60 d后,孵化率降为65.81%;大麦虫可作为花绒寄甲幼虫的替代寄主,最佳接虫比为1:5,此时化蛹率达70.40%,羽化率达94.03%;黄粉虫蛹、大蜡螟幼虫无法繁育出花绒寄甲成虫;黄粉虫幼虫干粉、大麦虫幼虫干粉、无菌水、脯氨酸、羟氨酸、丝氨酸、胱氨酸、葡萄糖、亚油酸混合配制的饲料使花绒寄甲成虫存活率达96.70%,单雌产卵量达161.10粒,产卵期持续43 d,是成虫的最佳人工饲料;经室内繁育的花绒寄甲一年发生2代,成虫寿命2～3年,卵期平均8.64 d、幼虫期平均6.63 d、蛹期平均36.88 d。花绒寄甲可用于防治桃红颈天牛,野外最佳释放比为8:1～ 10:1（天敌:天牛）,虫口减退率达72.70%。     

稻曲病菌菌核降解微生物的筛选与作用机制分析

菌核是稻曲病菌天然的越冬菌源和来年病害发生的重要初侵染源,控制田间菌核越冬数量能够从源头上遏制和减轻稻曲病的发生。为此,本研究对来自稻田土壤、菌核表面、以及青海高原的能够降解菌核的真菌进行了筛选,得到了6个有较好降解作用的生防菌株。在实验室条件下它们能够在30~70 d内彻底降解稻曲病菌菌核。真菌形态特征和rDNA-ITS序列分析表明,这些菌株分别为淡色生赤壳菌Bionectria ochroleuca、粘鞭霉Gliomastix polychroma、烟曲霉Aspergillus fumigatus、草酸青霉Penicillium oxalicum、粉红粘帚霉Gliocladium spp.和疣孢漆斑菌Myrothecium verrucaria。进一步超微结构观察发现,不同生防菌对菌核的降解机制可分为以重寄生作用和直接降解为主2种基本模式。春季田间撒施试验表明,其中2种生防菌的防治效果可达33.9%和46.8%。     

棘孢木霉菌鉴定及其对花生白绢病生防机制的研究

为了利用生防菌有效防控花生白绢病Sclerotium rolfsii,本研究采用稀释培养法从花生根际土中分离木霉菌,采用平板对峙法和盆栽试验筛选对花生白绢病具有高效生防效果的菌株并测定其生防机制,通过形态学、分子生物学技术和环境因子对发育的影响确定生防菌株的分类地位及生物学特性。结果表明,从分离的132株木霉菌中筛选出1株对齐整小核菌S.rolfsii具有高效抑菌效果的菌株GH-20,抑菌率达89.93%,将其鉴定为棘孢木霉菌Trichodermaasperellum。对峙培养时,菌株GH-20对齐整小核菌的拮抗指数达Ⅰ级,当其菌落覆盖病原菌菌落后,其菌丝缠绕和侵入病原菌菌丝,并使病原菌菌丝体逐渐消解、减少,导致病原菌不能产生菌核;菌株GH-20产生的挥发性代谢产物（volatile gas,VOG）和非挥发性代谢产物（non-VOG）对病原菌的抑菌率分别为59.95%和79.49%。盆栽试验结果表明,同时接种菌株GH-20和齐整小核菌对花生白绢病生防效果最好,为79.64%。另外,该菌株具有在以果糖为碳源,以酵母膏为氮源和pH7的条件下生长发育较好,光照有利于生长而光暗交替有利于孢子...     

营养添加剂对枯草芽孢杆菌G3 str在土壤中繁殖及其抑菌物质分泌能力的影响

从生防菌G3菌株筛选到的抗链霉素自然突变株G3^str,保持G3原有的抑菌活性,产伊枯草菌素和生物表面活性素,能抑制多种植物病原真菌.25℃下,营养添加剂对G3^str菌在不灭菌土壤中前5d有一定的增殖作用;10d后G3^str菌在土壤中主要以芽孢的形态存活;60d后,G3^str菌在土壤中仍以106cfu/g水平存活.G3^str菌在土壤中增殖时分泌少量的伊枯草菌素,但被快速分解;同时分泌较多的生物表面活性素,营养添加剂的加入明显促进其分泌.     

Hydrogen cyanide production by soil bacteria: Biological control of pests and promotion of plant growth in sustainable agriculture

Currently, plant diseases and insect infestations are mainly controlled by the extraneous application of pesticides. Unfortunately, the indiscriminate use of such agrochemicals can cause ecological and environmental problems, as well as human health hazards. To obviate the potential pollution arising from the application of agrochemicals, biological control of soilborne pathogens or insect pests using antagonistic microorganisms may be employed. Certain soil bacteria, algae, fungi, plants and insects possess the unique ability to produce hydrogen cyanide(HCN), which plays an important role in the biotic interactions of those organisms. In particular, cyanogenic bacteria have been found to inhibit the growth of various pathogenic fungi, weeds, insects, termites and nematodes. Thus, the use of HCN-producing bacteria as biopesticides offers an ecofriendly approach for sustainable agriculture. The enzyme, HCN synthase,involved in the synthesis of HCN, is encoded by the hcnABC gene cluster. The biosynthetic regulation of HCN, antibiotics and fluorescent insecticidal toxins through the conserved global regulatory GacS/GacA system is elaborated in this review, including approaches that may optimize cyanogenesis for enhanced pest control. In addition, the effects of bacterially synthesized HCN on the production of indole acetic acid, antibiotics and fluorescent insecticidal toxins, 1-aminocyclopropane-1-carboxylate deaminase utilization and phosphate solubilization may result in the stimulation of plant growth. A more detailed understanding of HCN biosynthesis and regulation may help to elaborate the precise role of this compound in biotic interactions and sustainable agriculture.     

放线菌剂及其与有机肥配施对魔芋的促生作用

【目的】探索生防放线菌剂及其与有机肥配施对魔芋生长的影响。【方法】2012-2013年采用小区栽培试验,以放线菌剂D74、H为材料,设7个处理:CK0不施肥;M施有机肥;D74+M20施用有机肥稀释20倍的菌剂D74;D74H+M20施用有机肥稀释20倍的菌剂D74H(D74和H按1∶1质量比混合而成);H+M20、H+M40、H+M80分别施用有机肥稀释20,40,80倍的菌剂H,研究放线菌剂及其与有机肥配施对魔芋生物学特性、根系及产量的影响。【结果】(1)放线菌剂与有机肥配施对魔芋根系生长、生物量及光合性能有明显的促进效应。D74+M20处理魔芋根系总长、总表面积、总体积、根系条数及鲜质量的菌剂与有机肥配施效应分别为331.3%,294.4%,262.5%,7.0%及93.4%。2012年D74H+M20、H+M20处理魔芋株高的菌剂效应分别为34.8%和33.0%;叶片绿色度的菌剂效应分别为28.4%和24.7%;叶片净光合速率和气孔导度的菌剂效应分别为99.3%,114.2%和52.1%,62.7%,差异均显著(P0.05)。(2)菌剂与有机肥配施具有抗病虫、增产效果,亦能提高球茎的商品性能。2013年,除H+M40处理之外,其余放线菌剂与有机肥配施处理的魔芋健株率和病株率的菌剂效应分别为32.7%~83.6%和17.6%~47.1%。2012年,D74+M20和D74H+M20处理魔芋球茎产量的菌剂效应分别为31.0%和42.9%;单个球茎鲜质量的菌剂效应均为19.1%;魔芋总产量的菌剂效应分别为27.1%和36.8%;2013年,D74+M20和D74H+M20处理魔芋不同指标的菌剂与有机肥配施效应分别为:球茎总数52.3%和52.3%,健康球茎个数100.0%和111.8%,腐烂球茎所占比例34.2%和62.0%,虫伤球茎所占比例34.6%和12.4%,总产量146.3%和120.2%。【结论】放线菌剂及其与有机肥配施可显著促进魔芋根系的生长,提高魔芋叶片净光合速率、产量及球茎的商品性能。     

Re-test of Rhinocyllus conicus host specificity, and the prediction of ecological risk in biological control

Biological control is proposed as an ecological strategy to manage the threat of invasive plants, especially in natural areas. To pursue this strategy, we need to know that the host specificity criteria used to evaluate ecological risk with deliberate introduction of an exotic insect for biocontrol are sufficient to predict potential impact on native species. Host specificity is defined by adult feeding and oviposition preferences and larval development. One way to evaluate the criteria is to re-examine case histories where ecological effects are recorded, such as that of Rhinocyllus conicus Frölich. This flower head weevil, released in North America in 1968 to control exotic thistles like Musk thistle (Carduus nutans L), is now reducing seed production by multiple native North American thistle species (Cirsium spp.), and local population density of Platte thistle (Cirsium canescens Nutt.). We hypothesized that host specificity of R. conicus has changed since pre-release testing, providing an explanation for the unexpected magnitude of the documented ecological effects. Instead, when we re-tested host specificity of weevils naturalized over 28 generations, we found that host specificity has not changed. Naturalized adults of R. conicus showed strong feeding and oviposition preference for Musk thistle over Platte thistle. In addition, larval development by these weevils was faster and more successful (to larger size) on Musk thistle than on Platte thistle. Thus, our results indicate that a change in host specificity cannot explain the unexpectedly large build-up of R. conicus and significant ecological effect on Platte thistle. We conclude that accurate prediction of the potential level of impact on native host plants in the field requires further ecological information in addition to host specificity.     

Harnessing Plant Growth Promoting Rhizobacteria Beyond Nature: A Review

Root-associated plant growth promoting rhizobacteria (PGPR) interact with the plant roots and influence plant health and soil fertility. Plant growth promoting rhizobacteria play an important role in plant growth by exerting various mechanisms such as biological nitrogen fixation, growth hormone production, phosphate solubilization, siderophore production, hydrolytic enzyme production, antagonistic activity against fungal pathogens etc. Hence, these are employed as inoculants for biofertilizer and biocontrol activities. This review summarizes various mechanisms of PGPR and their potential for use as inoculants. It shows that their use is a worthwhile approach for exploring disease management in conjunction with other strategies.