甘蓝夜蛾发生特点及赤眼蜂利用研究

通过两年的研究,明确了太原地区甘蓝夜蛾年发生三代。第一代幼虫为害期为5～6月,第二代为害期为7～8月,第三代为害期为9～10月。室内用4种赤眼蜂对甘蓝夜蛾卵进行了抑制孵化试验,寄生率分别为:螟黄赤眼蜂97.68%,广赤眼蜂92.91%,玉米螟赤眼蜂80.90%,松毛虫赤眼蜂53.51%。甘蓝田、苤蓝田释放螟黄赤眼蜂、广赤眼蜂防治甘蓝夜蛾,5月份螟黄赤眼蜂寄生率68.76%,广赤眼蜂寄生率56.25%;9月份螟黄赤眼蜂寄生率92.82%,广赤眼蜂寄生率88.16%。使用化学农药防治的甘蓝田、苤蓝田均未发现有赤眼蜂寄生。     

蔬菜品种对小猿叶甲生物学特性影响的研究

小猿叶甲取食不同品种蔬菜对其生长发育,存活和菜株上的产卵量都有影响。了食６种蔬菜的小猿叶甲,从幼虫到蛹期,取食白菜的发育历期、存活率和选择在白菜上的产卵量都显著地优于其他蔬菜,分别为２５．８８ｄ、８６．９９％和１２４．１０粒,而芥蓝对小猿叶的发育、存活和在菜株上的产卵量具一定的抑制作用,分别为２５．３６ｄ、４２．４８％入１．７０粒,表明了取食白菜有利于小猿叶甲种群的增长。     

芦荟不同溶剂提取物对白菜黑斑病菌的抑菌活性研究

用甲醇、乙醇、丙酮、乙酸乙酯、氯仿、苯、石油醚、正己烷8种溶剂对库拉索芦荟的抗菌活性物质进行提取,提取产率随溶剂极性的增强而提高.以白菜黑斑病菌为测试菌,用生长速率法测定芦荟各种溶剂粗提物的抑菌活性,当提取物浓度为10mg/mL时,各种溶剂粗提物均表现一定的抑菌效果,其中以石油醚、正己烷和乙酸乙酯的粗提物抑菌效果最好,分别为71.4 %、71.3 %和62.4 %.从抑菌效果及提取产率两方面考虑,乙酸乙酯为提取芦荟抑菌活性物质的最佳溶剂.通过测定甲醇、乙醇、丙酮、乙酸乙酯4种溶剂1 %～10 %系列浓度对白菜黑斑病菌的抑制作用及甲醇、丙酮、乙酸乙酯3种溶剂对各种芦荟粗提物的溶解性,确立用乙酸乙酯-水(7∶ 3,v/v)溶解各种粗提物进行生物测定,既能较好地溶解各种粗提物,又对测试菌的抑制作用相对较小.试验研究还筛选了2 ‰～1 %吐温20作表面活性剂乳化乙酸乙酯使其与所溶解的粗提物能均匀分布到PDA培养基中,保证了测定结果的准确性与稳定性.通过测定库拉索芦荟等7种芦荟水浸提物的抑菌活性,认为树芦荟、库拉索芦荟的抑菌效果最好.     

油菜根肿病菌的形态和休眠孢子的生物学特性

 【目的】比较油菜根肿病菌与十字花科蔬菜根肿病菌的形态是否存在差异。研究油菜根肿病菌休眠孢子的生物学特性，为防治油菜根肿病提供依据。【方法】应用扫描电镜观察油菜根肿病菌的形态特征和休眠孢子至管腔的形态演变过程。采用地衣红染色，观测不同根分泌物和条件对休眠孢子萌发的影响。【结果】休眠孢子近球形，有乳突，直径为1.9～4.3μm（平均3.5μm），大于甘蓝根肿菌休眠孢子（2.5μm）；透射电镜下游动孢子近球形、肾形或椭圆形，直径为1.6～3.5μm（平均2.8μm），同侧生不等长尾鞭式双鞭毛。休眠孢子萌发形成游动孢子、休止孢、休止孢再生出侵入结构管腔。休眠孢子萌发的最适温度是24℃，最适pH值是6.3，腐烂处理促进休眠孢子萌发，光抑制休眠孢子萌发，休眠孢子在过滤灭菌的根分泌物中萌发率最高为62.50％。致死温度为48℃。【结论】油菜根肿病菌与十字花科甘蓝根肿病菌休眠孢子大小有明显差异，观察到休眠孢子至管腔的过程。油菜根肿菌休眠孢子的萌发条件与该病发生条件相一致。     

Development of A Real-Time PCR Assay for Plasmodiophora brassicae and Its Detection in Soil Samples

A SYBR Green I real-time PCR assay was developed to detect and quantify Plasmodiophora brassicae ribosomal DNA(rDNA) and internal transcribed spacer(ITS).A pair of primers PBF1/PBR1 was designed based on the conservative region of rDNA-ITS of P.brassicae.The positive plasmid pB12 was obtained and used as the template to create standard curve.The specificity,sensitivity,and reproducibility of real-time PCR were evaluated respectively.Naturally and artificially infested soil samples containing different concentrations of P.brassicae were detected.The results demonstrated that standard curve established by recombinant plasmid was shown a fine linear relationship between threshold cycle and template concentration.The melting curve was specific with the correlation coefficient of 0.995 and that the amplification efficiency was 93.8%.The detection limit of P.brassicae genomic DNA was approximately 40 copies per 25 μL.The sensitivity of the assay was at least 100-fold higher than conventional PCR.Only DNA from P.brassicae could be amplified and detected using this assay,suggesting the highly specific of this assay.The coefficient of variation was less than 3%,indicating the PCR method revealed high reproducibility.The detection limit in soil samples corresponded to 1 000 resting spores g-1soil.Bait plants were used to validate the real-time PCR assay.This developed real-time PCR assay allows for fast and sensitive detection of P.brassicae in soil and should be useful in disease management and pest interception so as to prevent further spread of P.brassicae.     

甘蓝夜蛾核型多角体病毒光保护剂的筛选

以2龄初的甘蓝夜蛾幼虫为供试虫,通过生物测定确定荧光素钠、活性碳、黑色素3种物质对MbNPV的光保护作用。结果表明：0.1%的黑色素对MbNPV的光保护作用最强,紫外光照20、40、60 min后幼虫的校正死亡率显著高于其它处理。     

Effects of nC24 and nC27 petroleum spray oils on oviposition and egg survival of Ostrinia nubilalis Hübner (Lepidoptera,Pyralidae) and Trichogramma brassicae Bezdenko (Hymenoptera,Trichogrammatidae) adults on maize plants

Abstract

The study determined the effectiveness of nC24 and nC27 petroleum spray oils (PSOs) to reduce oviposition of Ostrinia nubilalis and survival of O. nubilalis eggs and Trichogramma brassicae adults. Under choice and no-choice tests, maize treated with 3, 5 and 10% (v/v) of both oils deter O. nubilalis oviposition on maize. The study also showed that treatment of 1 – 3-day-old O. nubilalis eggs with 1 and 2% (v/v) nC24 oil caused 6% mortality compared with 99.5% when treated with 3, 5 and 10% (v/v) oil. In contrast, treatment with 1 – 10% (v/v) nC27 oil caused 99% mortality. Trichogramma brassicae is a major parasitoid of O. nubilalis. The mortality of T. brassicae 24 h after exposure to maize sprayed with 2% (v/v) nC24 and nC27 oils was 8.3 and 12.7%, respectively. At 5% (v/v), the mortalities were 24.9 and 23.5%, respectively. Therefore, application of 3% (v/v) PSO may deter O. nubilalis egg lay, egg mortality and survival of T. brassicae on maize.     

Application timing of herbicides,glyphosate and atrazine,sway respective epidemics of foliar pathogens in herbicide-tolerant rapeseed

Rapeseed (Brassica napus) production in Australia relies heavily on triazine-or glyphosate-tolerant cultivars. For 14 triazine-tolerant cultivars, disease development of Neopseudocercosporella capsellae (white leaf spot), Alternaria brassicae and A. japonica (Alternaria leaf spot), and Hyaloperonospora brassicae (downy mildew) were all dependent upon herbicide application timing (p < 0.001), with significant differences between cultivars (p < 0.001) and a significant interaction (p < 0.001) between herbicide application timing and cultivars. Atrazine applied preinfection by N. capsellae, A. brassicae, or A. japonica enhanced disease incidence, severity, and leaf collapse, while atrazine application postinfection for these same pathogens reduced all three disease parameters. However, for H. brassicae, application of atrazine after, and especially prior to, infection resulted in lower disease incidence, severity, and leaf collapse. Application of glyphosate on five glyphosate-tolerant cultivars for N. capsellae resulted in significant differences (p < 0.05) between glyphosate application treatments, and between host cultivars in terms of incidence and consequent leaf collapse. For A. brassicae, A. japonica, and H. brassicae, glyphosate resulted in significant differences (p < 0.001) across application timings between cultivars, and a significant interaction (p < 0.001) between herbicide application timings and cultivars. Glyphosate applied on glyphosate-resistant rapeseed after, and especially prior to, attack by H. brassicae, reduced downy mildew. These are the first studies to highlight how the timing of application of triazine or glyphosate in relation to pathogen infection is critical to the susceptibility of rapeseed to white leaf spot, Alternaria leaf spot, and downy mildew. This new understanding offers fresh possibilities for improved management of these diseases in herbicide-tolerant rapeseed crops.     

十字花科根肿病的研究进展

概述了根肿病的危害与发生、病原菌的基本特征、病原菌的分离提纯与人工接种方法以及十字花科大白菜抗根肿病的研究等。     

甘蓝蚜的识别与防治

介绍了甘蓝蚜不同虫态的形态特征及为害特征,并与相似虫害桃蚜、萝卜蚜等进行比较。,同时总结了其发生规律和生活习性。然后从农业防治、物理防治、生物防治、化学防治等方面总结了该虫害的防治方法,并介绍了几种主要化学药剂的作用原理、使用方法、药效以及注意事项。