昆虫病原线虫对韭蛆和土壤线虫群落的影响

防治韭菜的主要地下害虫韭蛆（迟眼蕈蚊Bradysia odoriphaga）是造成韭菜农药残留超标主要原因。室内实验表明,生物天敌昆虫病原线虫Steinernema feltiae处理60h后,韭蛆杀死率显著高于使用农药的对照组。2010年4月18日在山东省寿光市丰城地区韭菜地施用昆虫病原线虫以防治韭菜的主要害虫韭蛆,同时以施用化学农药辛硫磷作为对照,处理后第35d和第175d调查结果表明,昆虫病原线虫处理组的昆虫病原线虫多度显著高于化学对照组,其中第175d调查结果表明,经昆虫病原线虫处理后的韭菜鲜重比化学农药处理的对照组增加了10.4%,但差异未达到显著效果。上述结果表明,昆虫病原线虫能够有效控制韭蛆危害。第35d取样结果表明,昆虫病原线虫处理组的土壤线虫群落Shannon多样性指数高于化学农药处理组;第175d调查结果表明,两种处理之间土壤线虫群落各指标相近。试验结果表明昆虫病原线虫能够有效防治韭蛆。     

昆虫病原线虫对烟草根结线虫及蚜虫病虫害以及蚜茧蜂寄生的影响

昆虫病原线虫(EPN)作为一类有潜力的生物防治物质,逐渐受到国内外学者的广泛关注。实验以烟草(Nicotiana tabacum)为研究对象,在人工控制条件下通过外源添加EPN(Steinernema carpocapsae和Heterorhabditis bacteriophora),探究了EPN对烟草地下部根结线虫、地上部烟蚜(Myzus persicae)及烟蚜-蚜茧蜂(Aphidius gifuensis)关系等多重营养级的影响。结果表明:(1)在人工去除烟蚜条件下,施加昆虫病原线虫能显著降低烟草根中根结线虫的卵粒数(P0.05);在有烟蚜的条件下,S.carpocapsae添加处理能显著降低烟草根中根结线虫的卵粒数或者卵粒指数(P0.05);(2)无论EPN添加与否,烟蚜种群生长曲线均很好地符合Logistic增长模型,达到平台期的时间为5~6 d;对照组、S.carpocapsae虫尸剂添加和H.bacteriophora虫尸剂添加这3种条件下,蚜虫种群的环境容纳量分别为89.6、99.8头·株-1和76.6头·株-1,而与之对应的烟草地上部干重分别为0.996、3.258 g·株-1和1.643 g·株-1,这一结果表明EPN添加降低了单位质量烟草叶片上烟蚜的环境容纳量;(3)蚜茧蜂投放早期(2、4、6 d),投放EPN处理组间的僵蚜数目差异显著(P0.05),S.Carpocapsae虫尸剂处理组显著低于H.bacteriophora虫尸剂处理组。研究结果表明,EPN添加可影响烟草地下部根结线虫的繁殖,也可通过"bottom-up"途径影响烟草叶面烟蚜的种群增长以及蚜茧蜂的寄生行为,且这些影响效果与EPN种类有关。     

昆虫病原真菌致病寄主的机制和基因工程改良

摘要：随着大量施用化学农药所造成的环境污染等问题日益突出，真菌杀虫剂的研究和开发受到了广泛的关注。由于存在击倒昆虫时间较长、对环境条件要求高等缺点，昆虫病原真菌的广泛应用受到限制。因此，有必要弄清昆虫病原真菌致病寄主过程的遗传学和分子生物学机理，找出控制毒力的主效基因。在此基础上，利用基因工程和细胞工程等技术提高菌株毒力，创造出更适合市场需要的真菌杀虫剂。文章重点介绍了近年来有关昆虫病原真菌致病机理的研究进展，包括侵染寄主过程中附着胞的形成、降解昆虫体壁的分子机理和昆虫病原真菌的毒素等。同时，还介绍了昆虫病原真菌的遗传转化方法和基因工程改良的一些新进展。     

昆虫病原线虫的培养及其对两种天牛的致病性测定

经筛选,Ｆ号培养基的线虫产量最高,１０ｄ开始可以看见大量子代线虫,２０ｄ线虫量最大,达到６０．７万头／ｇ,以液体培养基先培养共生细菌２ｄ,后和线虫悬浮液一起接种入线虫培养基,能获得最好的效果。人工培养的线虫在室内对光绿桔天牛（Ｃｈｅｌｉｄｏｎｉｕｍａｒｇｅｎｔａｔｕｍ）的致死率为４８ｈ达８６．０％。在田间施用时,由于虫道口小,虫道长而复杂,致死率稍低,为７０％左右;在室内对蔗根土天牛（Ｄｏｒｙｓｔｈｅｎｅｓｇｒａｎｕｌｏｓｕｓ）幼虫无致病作用。     

昆虫病原线虫与根瘤菌配合使用在花生栽培上的应用

为了探索昆虫病原线虫与根瘤菌配合使用的可行性,在室内测试了根瘤菌对昆虫病原线虫(Heterorhabdits bacteriophora,Taishan strain H06)存活及侵染率的影响;同时探究了在大田条件下花生不同生育时期,根瘤菌和昆虫病原线虫配合使用对花生植株性状、荚果产量及防治花生蛴螬的影响。结果显示:不同浓度的根瘤菌剂对线虫的存活均无亚致死作用,对线虫的致死率无明显影响;在结荚期,播种时接种根瘤菌的叶片厚度、重量及面积比对照分别提高了38.53%、16.75%和26.22%。结荚期施用H06线虫对蛴螬的防治效果达80.78%,显著高于其他处理的防治效果(38.78%)。播种期接种根瘤菌+结荚期施用线虫的处理使花生总荚数、荚果重和百粒重比对照分别提高了141.51%、220.66%和9.88%。因此,在实际应用中,建议将播种期接种根瘤菌与结荚期施用H06线虫配合使用,可起到防虫固氮双重效果,进而提高花生产量的目的。     

紫外辐射与复合胁迫对植物抗氧化酶系统的影响

植物抗氧化酶系统对UV-B辐射增强与复合胁迫的响应是植物抵御逆境伤害的关键机制之一。结合近年来国内外研究成果,概述了UV-B辐射对植物抗氧化酶基因表达、转录与翻译的影响,植物抗氧化酶系统对UV-B辐射与干旱、臭氧、高温、盐渍、重金属及酸雨复合胁迫的响应,以及CO2、抗坏血酸、α-萘乙酸、硒、激光辐射和稀土等调节因子对UV-B辐射下植物抗氧化酶系统的作用。     

UV-B辐射增强对木本植物的影响研究进展

阐述了UV B辐射增强对木本植物的影响研究进展 ,并指出UV B辐射增强对植物生态系统影响的研究方向。     

地表臭氧含量增加和UV-B辐射增强对大豆生物量和产量的影响

利用开顶式气室(OTC)设置4个处理对大豆进行O3与UV-B增强的大田试验,通过观测生物量和产量研究两者对大豆生长的影响。T1为O3含量100nmol/mol的处理,T2为UV-B辐射强度比CK增加10%的处理,T3为T1和T2的复合处理,CK为自然空气。结果表明,O3含量与UV-B辐射增强的单因素对大豆株高、叶面积、茎干重等生物量都有不同程度的负影响,而两者复合后对各生物量的影响效果不一致,在分枝期至结荚期拮抗作用居多,而协同作用则多出现在生育期末期。在整个生育期,各处理均表现为茎分配指数变化幅度较小,CK、T1、T2、T3的根和叶分配指数逐渐降低,且荚分配指数呈快速上升的趋势。由此可见,O3和UV-B辐射单因子胁迫对大豆生物量和产量均产生不同程度的负效应,而两者的复合作用并不是两个单独作用的简单累加。     

电子束辐照对灰葡萄孢菌分生孢子萌发活性及致病力的影响

以灰葡萄孢病菌(Botrytis cinerea)分生孢子为研究对象,采用0.5、1.0、2.0和3.0kGy剂量电子 束辐照灰葡萄孢分生孢子,分别测定5℃和25℃培养条件下辐照对灰葡萄孢分生孢子的萌发活性及致病力的影响.结果表明:25℃和5℃培养条件下,2.0kGy处理分生孢子完全萌发时间比对照分别延迟了5和9d;2...     

自然和人为条件下UV-B辐射减弱对烟草抗氧化酶活性的影响

采用盆栽试验,分别在云南玉溪主产烟区海拔高度存在一定差异的通海县(海拔1806.0m)和红塔区大营街(海拔1591.0m)两地,研究了自然条件下和通海县减弱25%、50%和65%UV-B辐射条件下,烟草K326大田生育进程中叶片SOD、POD和CAT等3种抗氧化酶活性与UV-B辐射变化的关系。结果表明:由于在局地范围内两地天气气候特征存在一定差异,致使UV-B辐射随海拔高度的变化与地处低纬高原的云南地区大尺度范围的普遍规律相反,烟草大田主要生长期的太阳UV-B辐射强度为大营街通海。大营街烟叶SOD和POD活性高于通海,减弱UV-B辐射后SOD活性发生不同变化,而POD活性随UV-B辐射减弱而下降,但各处理CAT活性变化几乎一致。从时间动态变化看,3种酶都与UV-B辐射变化呈负相关,SOD和POD活性与UV-B辐射变化相关性较高,表现出较强的累积效应,CAT活性变化几乎不受UV-B辐射变化的影响,7月下旬-8月上旬是各处理烟叶3种抗氧化酶活性差异的主要时期。结果说明,烟叶SOD、POD和CAT活性对UV-B辐射变化响应的敏感性存在较大差异,SOD和POD对UV-B辐射变化较敏感,成熟期是K326叶片SOD和POD活性对UV-B辐射变化响应的敏感时期。     

Development and reproduction of Sancassania polyphyllae (Acari: Acaridae) feeding on entomopathogenic nematodes and tissues of insect larvae

We studied the effect of different food sources, infective juveniles of the entomopathogenic nematodes, Steinernema feltiae and Heterorhabditis bacteriophora (Rhabditida: Steinernematidae, Heterorhabditidae), and tissues from the insect larva, Polyphylla fullo (Coleoptera: Scarabaeidae) or Galleria mellonella (Lepidoptera: Pyralidae), on the development, reproduction and longevity of Sancassania polyphyllae (Acari: Acaridae). We showed that the immature mite stages - protonymph and tritonymph - could develop to the next developmental stage on living or sonicated (i.e., ruptured) S. feltiae or H. bacteriophora. However, the mite larval stage could only develop to the next developmental stage on sonicated infective juveniles of the nematodes. Subsequently, we demonstrated that S. polyphyllae completed development from protonymph to adult on live S. feltiae or H. bacteriophora, whereas all immature stages of S. polyphyllae completed their development from larva to adult on insect tissues. The total developmental period of S. polyphyllae that fed on insect tissues was significantly shorter than those that fed on live infective juveniles. The pre-oviposition, oviposition, and post-oviposition periods and female longevity were not significantly different among the food sources. The total and daily fecundity of S. polyphyllae feeding on P. fullo and G. mellonella was significantly higher than those feeding on S. feltiae and H. bacteriophora, although there was no significant difference observed between P. fullo and G. mellonella or between S. feltiae and H. bacteriophora. The net reproductive rate (R₀) was highest (588.3♀/♀) when S. polyphyllae fed on P. fullo. The longest mean generation time (T₀) occurred on H. bacteriophora (12.6 days) and the shortest occurred on P. fullo (10.5 days). S. polyphyllae, which fed on P. fullo (r_m=0.61) and G. mellonella (r_m=0.55) had the highest intrinsic rate of increase (r_m) compared to mites that fed on S .feltiae (r_m=0.45) and H. bacteriophora (r_m=0.41).     

紫外线(UV-B)辐射对不同色型豌豆蚜生物学特性的影响

为了明确紫外线(UV-B)辐射对红色型和绿色型豌豆蚜生物学特性的影响,本研究将2种不同色型豌豆蚜的初生若蚜经过40 W UV-B波段紫外线每日照射30 min,在3种温度梯度(16℃、20℃、24℃)和2种苜蓿品种"甘农3号"和"甘农5号"条件下,在人工气候箱中单头饲养,测定各个处理豌豆蚜的发育历期、体质量差和相对日均体质量增长率等生物学参数。结果显示:在"甘农3号"上,16℃时,在UV-B辐射对2种色型豌豆蚜的发育历期、体质量差和日均体质量增长率均无显著影响(P>0.05);在20℃时,UV-B辐射下红色型豌豆蚜的发育历期显著延长(P<0.05),相对日均体质量增长率也显著减少(P<0.05),体质量差无显著变化(P>0.05);而在24℃时,UV-B辐射下绿色型豌豆蚜的发育历期显著延长(P<0.05),体质量差和相对日均体质量增长率也显著减少(P<0.05)。在"甘农5号"上,在16℃时,UV-B辐射下红色型豌豆蚜的发育历期显著延长(P<0.05),体质量差和相对日均体质量增长率也显著减少(P<0.05);在20℃和24℃时,UV-B辐射绿色型豌豆蚜的发育历期显著延长(P<0.05),体质量差和相对日均体质量增长率也显著减少(P<0.05)。由此可知,UV-B辐射对豌豆蚜的影响与温度和苜蓿品种均密切相关。     

The combined effects of enhanced UV-B radiation and selenium on growth, chlorophyll fluorescence and ultrastructure in strawberry (Fragaria × ananassa) and barley (Hordeum vulgare) treated in the field

The possible ameliorative effects of selenium (Se) addition to soil on the detrimental effects of enhanced UV-B radiation were tested on strawberry and barley during 4 months of field experiment in Kuopio, Central Finland. Control plants were exposed to ambient levels of UV radiation, using arrays of unenergized lamps. A control for UV-A radiation was also included in the experiment. Added Se, applied as H₂SeO₄, at the level of 0.1 mg kg⁻¹ soil (low dosage) and 1 mg kg⁻¹ soil (high dosage) increased Se concentrations in plants more than 10 and 100 times, respectively. After 4 months of exposure, strawberry and barley plants were harvested for biomass analysis. Chlorophyll fluorescence was measured using the Hansatech FMS2 fluorescence monitoring system. Leaf anatomy and ultrastructure were observed by light and transmission electron microscope. Several effects of UV and Se as well as their interaction were found, mostly for strawberry, but not for barley, indicating species-specific responses. Our results provided evidence that the high Se concentration in soil had no ameliorative effect but increased the sensitivity of strawberry to enhanced UV-B radiation in the field. Under ambient radiation, Se did not alter leaf growth of strawberry, whereas under UV-B radiation, the high Se addition significantly decreased leaf growth. Strawberry runner biomass was affected by the interaction of Se and UV. Under ambient radiation Se did not change dry weight of runners, but in combination with UV-A or UV-B radiation the high Se dosage decreased dry weight of runners by about 30%. Although the high Se concentration positively influenced on quantum efficiency of photosystem II (PSII) in strawberry leaves, it reduced runner biomass, leaf number and ratio of starch to chloroplast area. This suggests that the harmful effects of the high Se dosage on photosynthetic processes occurred as a result of changes in activity or/and biosynthesis of enzymes, rather than alteration of PSII. At the low concentration, Se effects were slight and variable.Although barley leaves accumulated higher Se concentrations than strawberry, there were no apparent changes in their growth, biomass or chlorophyll fluorescence due to Se effect either alone or in combination with UV-B. However, at the ultrastructural level, an enlargement in the peroxisome area was found due to combination of UV radiation with Se, suggesting the activation of antioxidative enzymes, possibly catalase. Decrease in mitochondrial density in barley cells in response to Se might be attributed to alteration of mitochondrial division. Increase in the proportion of cells with cytoplasmic lipid bodies due to combined effect of UV-B and Se indicated the alteration of lipid metabolism and the acceleration of cell senescence in barley. Main UV-B effects were found, mostly at the tissue and ultrastructural level in strawberry, but not in barley, indicating species-specific susceptibility to enhanced UV-B radiation. UV-B-treated strawberry plants developed marginally thinner leaves with reduced ratio of starch to chloroplast area in their cells, suggesting negative influence of UV-B on photosynthetic processes.     

玫烟色拟青霉对小菜蛾幼虫的侵染过程及接菌方法对其致病力的影响

采用扫描电镜观察玫烟色拟青霉(Paecilomyces fumosoroseus)分生孢子在小菜蛾(Plutella xylostella)幼虫体表的萌发和侵染过程及玫烟色拟青霉孢子粉、孢子悬浮液和孢子培养液对小菜蛾幼虫的致病力.结果表明:小菜蛾幼虫体表嵴状突起结构区附着的孢子较多, 刺状突起结构区附着的孢子较少;刺状突起结构区附着的孢子萌发较早, 多数孢子在接菌后16 h开始萌发, 而嵴状突起结构区附着的孢子多数在20 h开始萌发, 在平缓结构区孢子萌发最迟.在嵴状突起结构区和刺状突起结构区, 多数孢子萌发后产生芽管, 直接以芽管侵入幼虫体壁, 少数形成附着胞侵染寄主.此外玫烟色拟青霉3种不同接菌方法对小菜蛾幼虫的侵染速率和致病力大小明显不同, 其中孢子培养液比孢子悬浮液和孢子粉对小菜蛾幼虫的侵染速率快, 接菌44 h虫体表现出明显的感病症状, 致死中时为3.18 d;孢子悬浮液和孢子粉处理的小菜蛾幼虫, 60 h虫体出现感病症状, 致死中时分别为4.20 d和4.34 d;而且致病力大小也存在明显差异, 接孢子粉的处理明显高于孢子悬浮液和孢子培养液, 小菜蛾幼虫6 d的死亡率达76.2%, 而其他两种处理小菜蛾幼虫6 d的死亡率仅为59.8%和58.5%.本研究结果表明, 小菜蛾幼虫的体表结构影响玫烟色拟青霉孢子在寄主体表的附着、萌发和侵入, 玫烟色拟青霉孢子粉对小菜蛾幼虫的致病力最强, 明显高于孢子悬浮液和孢子培养液.     

Addition of hydrogels to soil for prolonging the survival of Pinus halepensis seedlings subjected to drought

The effect of an amendment of a sandy soil with superabsorbent hydrogels (Stockosorb K 400, a highly cross-linked polyacrylamide with about 40% of the amide group hydrolysed to carboxylic groups) on the survival of Pinus halepensis seedlings during water stress was studied, with the following concentrations added to the soils: 0.04%, 0.08%, 0.12%, 0.20%, and 0.40%. The water retention of the soil increased exponentially with increasing additions of hydrogel to the soil. The highest concentration used changed the water retention capacity and its change in water potential with regard to its water content from a typical sand to a loam or even silty clay. During desiccation under controlled conditions, the seedlings treated with 0.4% hydrogel survived twice as long in the soils amended with 0.4% hydrogel as in the control soils. During the drought, the seedlings exhibited a pronounced growth both of the shoot and the roots, which was about three-fold higher than the one of the plants in the control soils. The data indicate that an amendment of soils with this type of hydrogels at 0.4% (w/w) will greatly enhance the drought tolerance of the seedlings growing on this substrate. A comparison between the reaction of the plants in the hydrogel amended soils and the pF-curve measured with the plate test revealed that less water was actually available for the plants, as could be expected from the pF-curves.     

Effect of seasonality and agricultural practices on occurrence of entomopathogenic nematodes and soil characteristics in La Rioja (Northern Spain)

The effects of seasonality and land management on entomopathogenic nematodes (EPNs) distribution and on soil characteristics were studied in natural areas and agricultural fields under organic and conventional management in La Rioja (Northern Spain). The population density of the native EPNs as well as air temperature, rainfall, soil fertility, soil moisture, and soil content of heavy metals were seasonally recorded over 2 consecutive years. The highest occurrence of EPNs was observed in autumn, followed by spring and summer. Agricultural management influenced the amount of soil organic matter, nutrients and heavy metals, as well as soil volumetric moisture and temperature, leading to statistical differences mainly between natural and agricultural sites, but also in some cases between different types of agricultural management. The usefulness of soil organic matter, C, N, P and K content, as well as the C/N, C/P and N/P ratios as indicators for differentiating conventional and organic crop management as well as the role of agricultural practices such as tillage and fertilizing is discussed.     

UV-B辐射对植物水分代谢的影响

为系统了解UV-B辐射对植物水分代谢的影响, 本文从生理、生化两个角度概述了近30年国内外相关方面的研究成果, 内容涉及UV-B辐射对植物根系活力、蒸腾速率、水分利用效率及植物不同发育期叶片脯氨酸、可溶性糖含量的影响;总结了UV-B辐射对植物气孔行为的影响及相关机理, 包括植物体内ABA、H2O2、NO等信号分子含量的变化以及这些信号分子在调节气孔行为方面发挥的作用.认为UV-B辐射对植物水分代谢产生伤害, 且此伤害作用与植物种类、发育阶段有关, 与UV-B辐照时间及剂量正相关.研究UV-B辐射对植物水分代谢的影响, 对自然及农业生产环境下规避UV-B辐射对植物产生逆境胁迫效应具有积极的环境生态学价值.     

Influence of irrigation on the distribution and control of the nematode Meloidogyne javanica by the biocontrol bacterium Pasteuria penetrans in the field

Pasteuria penetrans, a bacterial parasite of plant-parasitic nematodes, is used to control root-knot nematode Meloidogyne spp. populations in vegetable crops. But its efficiency is variable, mostly because of the patchy distribution of the bacteria in arable fields. As the infective P. penetrans are non-motile bacteria in soil, abiotic soil factors can affect the bacteria–nematode relationships. An epidemiological study, conducted in a vegetable field, showed that abiotic factors such as irrigation, soil water holding capacity and texture, affected the efficiency of P. penetrans. A correspondence analysis between these abiotic factors and the density of P. penetrans spores in the soil, and the proportion of Meloidogyne javanica juveniles infected by the bacteria, revealed that irrigation affected directly the distribution of the spores in soil pores related to their passive transport by water flow. Laboratory experiments conducted on the passive transport of spores confirmed that intensive irrigation leached the spores down the soil profile and decreased the percentage of infected Meloidogyne juveniles.