新疆棉疫病及其病原菌研究鉴定

新疆吐鲁番棉区1984年以来,发生棉株青枯死亡,在百亩棉田中调查,株致死率达10—15％。经对病原菌形态观察、适生温度的调查、回接和交叉接种试验,确定为棉疫病,致病病原是寄生在哈密瓜上的优势菌种德雷疫霉菌。     

淡紫拟青霉菌IPC菌株诱变育种方法比较

淡紫拟青霉菌Paecilomyces lilacinus(Thom)Samson是一种重要的根结线虫卵寄生菌,同时是多种昆虫及其他植物寄生线虫的重要天敌,具有极高的应用价值.Jatala等[1]发现该菌对南方根结线虫Meloidogyne incognita的卵寄生率高达60%～70%.作者采用紫外线等方法对淡紫拟青霉菌IPC菌株进行了诱变选育,以便进一步提高其防效及应用价值.     

微波诱变选育高效溶磷木霉菌株的研究

为了获得高效溶磷菌株,对木霉菌T6菌株进行微波诱变处理,测定并分析了微波输出功率和辐照时间等参数对诱变效果的影响。结果表明:最佳诱变条件是微波输出功率900 W,辐照时间70 s,且在此条件下得到8株具有较高溶磷能力的突变菌株T6-9、T6-33、T6-93、T6-126、T6-157、T6-188、T6-196和T6-203。经过多代转接培养最后得到一株遗传稳定的溶磷木霉菌株T6-157,该菌株在液体培养条件下溶磷量为204.46 mg·L~(-1),与出发菌株相比,溶磷量提高了107.97%,植酸酶活性提高了57.35%,且突变菌株对土传植物病原菌的拮抗能力也有所提高。     

蝉拟青霉固态培养条件筛选及优化

蝉拟青霉Paecilomyces cicadae是一种对鳞翅目Lepidoptera、膜翅目Hymenoptera等多种昆虫具有较强致病性的虫生真菌 [1-2].目前,对于蝉拟青霉固态发酵培养方法的报道较少 [3].为进一步开发利用该菌株,作者以一株分离自山蝉Cicada flammata若虫僵尸的蝉拟青霉LB菌株为对象,筛选并优化了固态培养基及培养条件.     

一些拟青霉菌株对小菜蛾致病性的初步研究

研究了29株拟青霉和1株白僵菌对小菜蛾的致病性。结果表明不同菌株对小菜蛾的致病性有明显差异,其中玫烟色拟青霉,环链拟青霉和球孢白僵菌对小菜蛾感染致死效果最好。另外,分离自虫体的拟青霉菌株对小菜蛾具有较好的致病性,而来自土壤的菌株对小菜蛾无致病性或仅具微弱致病性。环链拟青霉对小菜蛾的致病性与产孢量存在一定的相关性,与地理来源无明显相关性。     

福建省辣椒疫霉菌群体结构表型特征分析

为了明确福建省辣椒疫霉菌群体遗传结构的表型特征,对分离自福建省15个市(县)的300株辣椒疫霉菌的交配型、甲霜灵敏感性及生理小种进行了测定。结果显示,288株为A2交配型,12株为A1交配型,出现频率分别为96%和4%,以A2占优势,在各采集点均有分布。263株对甲霜灵表现敏感,28株为中间型,9株为抗性,分别占总体的87.67%、9.33%和3.00%,甲霜灵敏感菌株为主要菌系。根据菌株对辣椒疫霉菌生理小种鉴别寄主的致病性测定结果,可将辣椒疫霉菌划分为3个生理小种,其中168株为小种3,126株为小种2,6株为小种1,分别占56%、42%和2%,小种3为福建辣椒疫霉菌优势小种。     

抗甲霜灵辣椒疫霉菌株的生物学特性

为了明确抗甲霜灵辣椒疫霉菌株的适生性,以田间自然产生及室内诱变获得的抗甲霜灵辣椒疫霉菌株为材料,测定了抗甲霜灵辣椒疫霉菌株的主要生物学性状。各菌株的游动孢子囊产生量为9.6×103～13.0×103个/mL,孢子囊释放率为61.3%～68.4%,游动孢子萌发率为35.3%～42.1%,适温条件下的菌丝平均生长速率约为10.28～11.55 mm/天;各菌株在含100μg/mL孔雀石绿的CA培养基上均不能生长,淀粉水解指数为0.18～0.95;接种辣椒、番茄、南瓜、西葫芦和茄子等果实所致病斑平均直径分别为34.11、18.47、30.19、37.78和32.73 mm。经方差分析,抗甲霜灵辣椒疫霉菌株的生物学性状与敏感菌株无显著差异,表明甲霜灵并未改变其生物学性状,辣椒疫霉对甲霜灵具有较高的抗性风险。     

棉隆与淡紫拟青霉联合防治番茄根结线虫病的效果评价

为明确土壤熏蒸与生防微生物对番茄根结线虫病的联合作用效果,采用移栽前棉隆熏蒸处理后穴施淡紫拟青霉Paecilomyces lilacinus YES-2-14生防菌剂的方法在温室大棚开展了联合防治试验。结果表明,棉隆用量为35 g/m~2时,24周拉秧时线虫数量减少90%以上,防效达到85.5%;移栽时穴施浓度10~7~10~8CFU/g的淡紫拟青霉菌剂,24周拉秧时防效为44.4%~59.6%;而当线虫初始密度达到674头/100 g土时,单一菌剂防效只有12.5%,但番茄长势和产量显著提高。棉隆熏蒸后再联合施用淡紫拟青霉菌剂,2个月和5个月时防效比单一棉隆处理分别提高14.1%和21.8%,比单一菌剂处理提高14.3倍和4.1倍,产量较对照、棉隆熏蒸和单一菌剂处理分别提高22.1%、9.5%和2.4%,且该处理地块线虫数量始终最低,与对照差异显著,而淡紫拟青霉数量则高于单一淡紫拟青霉菌剂处理。表明棉隆和淡紫拟青霉菌剂联合使用不仅能显著降低线虫数量,有效防治番茄根结线虫病,还能够促进植株生长并提高产量。     

一株虫生真菌杀线虫活性代谢产物的分离与结构鉴定

以生物活性为导向,利用硅胶、凝胶柱层析法以及高效液相色谱等技术对一株虫生真菌拟青霉菌Paecilomyces sp.的活性次生代谢产物进行了研究。从其活性组份中共分离得到2个杀线虫活性次生代谢产物,经质谱和核磁共振等波谱分析方法鉴定其结构分别为脑苷酯类化合物Cerebroside A( 1 )和 Cerebroside B( 2 )。活性测定结果显示,这2个化合物均具有杀松材线虫Bursaphelenchus xylophilus活性,其中化合物 1 在质量浓度分别为1 000,100和10 μ g/mL下对松材线虫的致死率分别为100%,100%和11.1%。     

蝉棒束孢交配型基因的分析和检测

蝉棒束孢Isaria cicadae为药用真菌蝉花的无性型,在防治同翅目害虫上具有重要作用。在自然状态下蝉棒束孢多以孢梗束状态存在,其子实体阶段极为少见。交配系统是真菌有性生殖过程中的决定因素,因此可从交配型的角度探究蝉棒束孢有性子实体稀少的原因。本研究运用RACE技术首次从蝉棒束孢中克隆出MAT1-1-1与MAT1-2-1全长cDNA序列,并进行生物信息学分析。根据cDNA序列设计并优化得到蝉棒束孢交配型鉴定引物,并对采集自安徽地区40株蝉棒束孢交配型进行鉴定,结果表明交配型MAT1-1菌株14株、MAT1-2菌株26株,并没有检测到同时含有两种交配型或两种交配型全部缺失的现象,因此蝉棒束孢有性型子实体几无发生的现象并不完全归因于交配型因素。     

Cross-resistance potential of fipronil in Musca domestica

The toxicity of fipronil to insecticide-susceptible houseflies and the cross-resistance potential of fipronil were determined for six insecticide-resistant laboratory housefly strains by topical application and feeding bioassay. The insecticide-resistant strains represented different levels and patterns of resistance to pyrethroids, organophosphates, carbamates and organochlorines. Five strains were almost susceptible to fipronil in feeding bioassay with resistance factors at LC50 between 0.36 and 3.0. Four of these strains were almost susceptible to topically applied fipronil (resistance factors at LD50 were 0.55, 0.83, 3.3 and 2.5, respectively), whereas one strain was 13-fold resistant to topically applied fipronil. A highly gamma-HCH-resistant strain, 17e, was 430-fold resistant to fipronil in topical application bioassay and 23-fold resistant in feeding bioassay at LD50/LC50. We also tested the toxicity of fipronil in a feeding bioassay and gamma-HCH in topical application bioassay on thirteen housefly field populations. Eleven of the field populations had resistance factors for fipronil ranging from 0.98 to 2.4 at LC50, whereas two populations were 4.0- and 4.6-fold resistant to fipronil. The resistance level to gamma-HCH at LD50 in the field populations ranged from 1.8- to 8.1-fold. The two strains showing fipronil resistance were 3.4- and 8.1-fold resistant to gamma-HCH. Fipronil and gamma-HCH toxicities were positively correlated in the field populations. Biochemical assays of esterase, glutathione S-transferase and cytochrome P450 monooxygenase indicated that the low fipronil resistance observed in laboratory and field strains could be caused by elevated detoxification or be due to a target-site resistance mechanism with cross-resistance to gamma-HCH.     

The effects of some factors on the growth and morphology of Naegleria sp. and three strains of the genus Acanthamoeba.

The effects of various biophysical and chemical factors on the cytology of vegetative stages of Naegleria sp., Vitek strain, Acanthamoeba culbertsoni, Acanthamoeba castellanii, Neff strain and Acanthamoeba polyphaga, No. 1289, were studied. The amoebae were cultured in a liquid medium under axenic conditions. The optimum temperature was 37 degrees C for pathogenic strains of Naegleria sp. and Acanthamoeba culbertsoni and 20 degrees C for A. castellanii. No changes were observed in the growth of A. polyphaga at the temperatures 20 degrees and 37 degrees C. The strains investigated grew at pH values of 5.6 to 7.7 using Soerensen's buffer. At the limit values the growth was inhibited and the morphology of cells was markedly changed. All of the four strains grew still at pH 8.4 kept by NaHCO3. A. polyphaga grew at partial anaerobiosis. The three tested strains of the genus Acanthamoeba grew in liquid axenic medium with 0.89% NaCl. The growth of Naegleria sp., Vitek was inhibited already at 0.2% concentration of this salt. The addition of 3 X 10(-2) m KCl to the culture medium had a harmful effect on the growth and morphology of three tested strains, except A. polyphaga. In the culture medium containing 2 X 10(-3) m CaCl2 the encystment of both pathogenic strains was stimulated. The cytological changes under experimental conditions were manifested by atypical movement of trophozoits and their intracellular structure.     

Effect of imidacloprid on the reproduction of acaricide-resistant and susceptible strains of Tetranychus urticae Koch (Acari: Tetranychidae)

Occasional reports linking neonicotinoid insecticide applications to field population outbreaks of the two-spotted spider mite, Tetranychus urticae Koch, have been a topic of concern for integrated pest management (IPM) programmes, particularly in apples. In order to shed light on the factors which may contribute to the occasional field population increase of T. urticae following the application of neonicotinoid insecticides, greenhouse experiments have been set up. Four different T. urticae strains, namely GSS (acaricide-susceptible), WI (organophosphate-selected), USA (a largely uncharacterised strain) and Akita (METI (mitochondrial electron transport inhibitor) acaricide-resistant and cross-resistant to dicofol), were compared for their fecundity without insecticide treatment and for their ovipositional response to foliar and drench applications of the field-relevant dose of imidacloprid (100 mg litre(-1)). Without insecticide treatment, strain GSS laid significantly more eggs (162.50 (+/- 5.43)) than the multiple resistant strain Akita (139.90 (+/- 5.54)) during a 16 day oviposition period. With imidacloprid treatment the highest effect was observed with GSS, with a significantly reduced number of eggs in drench (143.40 (+/- 4.22)) and foliar (144.60 (+/- 5.85)) applications. For strains Akita and USA, no significant differences were observed in oviposition between imidacloprid treatments and controls. The proportion of F1 female offspring decreased significantly with drench application for GSS and WI, while no differences were observed among strains in the survival of F1 immature stages, except for strain USA. The viability of eggs was relatively high (from 82.9 (+/- 4.5)% for USA to 95.2 (+/- 1.2)% for GSS) and not affected by imidacloprid treatments.     

Mechanisms of DDT resistance in larvae of the mosquito Aedes aegypti L

Larvae of eight strains of Aedes aegypti were exposed to DDT and compared for resistance, DDT uptake, in-vivo breakdown of DDT and residual unmetabolised DDT. Resistance varied widely between strains, three being fully susceptible, two almost immune and three of intermediate resistance. Breakdown of DDT by dehydrochlorination to 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (pp'-DDE) occurred in all strains and was greater in the five resistant types, but there was no significant correlation between the extent of breakdown in the resistant strains and the level of resistance. Moreover the overall difference between susceptible and resistant strains disappeared when they were compared at a low, almost sublethal, concentration of DDT. Larvae of resistant strains carried a greater absolute quantity of unmetabolised DDT in the body and were able to tolerate levels of DDT that were lethal to susceptible larvae. However the two most resistant strains (T8 and B51) contained significantly less DDT plus pp'-DDE than strains of intermediate resistance (T30 and BSJ) from which they had been derived. Addition of the synergist chlorfenethol to DDT increased its knockdown effect on all resistant strains, suggesting that dehydrochlorination was a factor in resistance. Three strains, two DDT-resistant and one DDT-susceptible, were tested with 1,1-bis(4-ethoxyphenyl)-2,2-dimethylpropane (I), an insecticide that cannot be dehydrochlorinated. All the strains were relatively tolerant to it although the DDT-susceptible strains were less tolerant. Addition of the synergist sesamex decreased the level of tolerance to I in all strains which suggested that microsomal oxidation made some contribution to it. It is concluded that three factors contribute to larval DDT resistance in A. aegypti; (a) increased metabolism to pp'-DDE; (b) increased tolerance to unmetabolised internal DDT; and (c) reduced content of DDT+pp'-DDE (only in the most resistant strains and due either to reduced absorption or increased excretion). These factors are discussed in relation to known larval resistance genes R^DDT1 and y.     

甘薯青枯病菌毒素产生条件的研究

 用致病力不同的甘薯青枯菌株(Pseudomonas solanacearum)进行毒素产生条件研究。试验结果表明,不同pH值、培养天数、菌株浓度及不同致病力的菌株所制备的毒素毒力差异达显著和极显著,但不同培养温度所制备的毒素毒力差异不显著。用Lotus1-2-3电脑软件综合分析以上产毒条件对所制备的甘薯青枯菌毒素的毒力影响程度,计算出强、弱和混合菌株产生毒素的3个最优回归方程。分别用Basic和Fortran语言编写程序,求出强、弱和强弱混合的甘薯青枯病菌产生毒素的3个最优模式为:①强菌株:pH=7,菌株浓度10⁸菌细胞/m l,培养天数3 d。②弱菌株:pH=7,菌株浓度10¹²菌细胞/ml,培养天数2 d。③混合菌株:pH=7,菌株浓度10¹⁴菌细胞/ml,培养天数1 d。培养温度均为25~35℃。     

辣椒疫霉对烯酰吗啉的敏感性基线及室内抗药突变体研究

 采用菌丝生长速率法测定了125株采自河北、内蒙古、陕西、安徽和北京等地区的辣椒疫霉病菌对烯酰吗啉的敏感性,结果表明,其EC₅₀值分布于0.126~0.318μg/mL之间,最不敏感菌株是最敏感菌株的2.5倍,平均EC₅₀=(0.218±0.0368)μg/mL。125个菌株对烯酰吗啉的敏感性分布呈单峰曲线,未出现抗性的病原菌亚群体,可将该单峰曲线作为辣椒疫霉对烯酰吗啉的敏感性基线,将烯酰吗啉对该病原群体的平均EC₅₀值作为田间抗药性监测的参考标准。通过紫外诱变敏感菌株N-7的菌丝获得了12株抗烯酰吗啉的突变体,抗性指数在16.38~132.15之间;通过紫外诱变敏感菌株DZ-16的游动孢子获得1株抗性指数为680倍的高抗药水平的突变体。突变体的部分生物学性状研究表明,其致病力与敏感菌株相当;大部分突变体产生孢子囊的能力与亲本菌株相比均有不同程度的提高;离体条件下,突变体和亲本菌株释放游动孢子的能力相当;突变体的菌丝生长速率与亲本菌株相比具有不同程度的差异。测定了敏感亲本菌株和突变体的交配型,均为A1型菌株,经紫外诱变后交配型没有发生改变。综合分析表明,抗性突变体的产生有利于抗药性群体的发展。为避免和延缓抗药性的产生,生产上应将烯酰吗啉与其它无交互抗药性的杀菌剂交替使用。     

影响大豆花叶病毒种子传毒和种子斑駁因素的研究

 本文研究了影响大豆花叶病毒种子传毒及种子斑驳的有关因素,以及种子传毒与种子斑驳的关系。结果表明,种子传毒率的高低受大豆品种,大豆花叶病毒(SMV)毒株,大豆感病早晚以及环境条件的影响。这些因素之间对种子传毒还存在交互作用。供试的12个大豆品种中,传毒率最高的为47%,最低的为25%;包括SMV Ⅰ,Ⅱ,Ⅲ号3个株系群的8个毒株在东农64-3513上传毒率的变化范围为1-33%,在抗霉2号上的变化范围为9-48%;大豆在开花以前感染SMV,种子传毒率可达45%,开花以后感病,种子基本不能传毒。
种子斑驳率因大豆品种,SMV毒株不同而异,并受品种与毒株交互作用的影响。种子斑驳既不代表种子带毒,也不代表种子传毒;从感病植株上采收的大豆种子,其斑驳种子与非斑驳种子的传毒率基本相同(P>0.05),因此,不能从种子斑驳率预测种子传毒率。     

Frequencies of the M918I mutation in the sodium channel of the diamondback moth in China, Thailand and Japan and its association with pyrethroid resistance

In addition to the allele frequencies of the L1014F and T929I mutations which are involved in nerve-insensitive resistance to a pyrethroid, those of the M918I mutation were examined using field strains obtained in China, Thailand, and Japan during 2009-2011. Results show that the resistance allele frequencies at the L1014F site were 89-100%, 97-100% and 65-85%, respectively, for strains in China, Thailand, and Japan. The respective allele frequencies at the T929I site were 86-100%, 70-97% and 58-84% for Chinese, Thai, and Japanese strains. With low frequencies up to 27%, M918I was found in Japan and China, but not in Thailand. The strain homozygous for the M918I and L1014F mutations was established and its resistance level to a pyrethroid was examined. The strain lacks a portion of the sodium channel gene corresponding to the 3′ portion of exon 18a, intron 18, and the 5′ portion of exon 18b. Nevertheless, the strain showed a similar level of resistance to that which was homozygous for the T929I and L1014F mutations.     

The role of metabolic enzymes in insecticide-resistant colorado potato beetles

Several metabolic enzymes were assayed in susceptible and insecticide-resistant (R-mfo and R-AchE) strains of the Colorado potato beetle (Leptinotarsa decemlineata Say). We compared the activities of esterases, glutathione transferases and mixed function oxidases, and measured in-vivo metabolism of carbofuran to determine the contributions of metabolic factors to the observed resistance. There were no substantial differences between strains in α- or β-naphthylacetate hydrolysis, or in glutathione transferase activity. Compared to the susceptible strain, the R-mfo strain showed 4-fold higher activity in both ethoxyresorufin-O-dealkylase, and pentoxyresorufin-O-dealkylase activity. The R-AChE strain had a 1.5-fold higher level of ethoxyresorufin-O-dealkylase activity. Correspondingly, the in-vivo metabolism of carbofuran was highest in the R-mfo strain, and the R-AChE strain was slightly higher than the susceptible strain. These results are discussed in relation to other resistance mechanisms which we have examined in these strains.     

Ecological Studies of Transformed Trichoderma harzianum Strain 1295-22 in the Rhizosphere and on the Phylloplane of Creeping Bentgrass

ABSTRACT A beta-glucuronidase (GUS) reporter gene and a hygromycin B (hygB) phosphotransferase gene were integrated separately into the Trichoderma harzianum strain 1295-22 genome, using biolistic transformation. The mycelial growth and biocontrol ability of the transformed strains did not differ from that of the original strain. The transformed Gus(+)-kanamycin-resistant (Gus(+)Kan(R)) strains were used to monitor growth and interactions with Rhizoctonia solani on creeping bentgrass plants. The hygB-resistant (hygB(R)) strains were used to selectively recover strain 1295-22 from the rhizosphere soil and phylloplane of creeping bentgrass after spray applications. The population levels of two hygB(R) strains and the original strain were very similar for all treatments. All three strains persisted for the duration of the experiment (28 days) in both the rhizosphere soil and on leaves, although population levels declined somewhat over the course of the experiment in unautoclaved soils. In this study, the results demonstrated that hygB(R) strains remained dominant over time when assayed on Trichoderma-selective medium containing hygB. The hygB(R) strains were not displaced by strains that colonized untreated plants. Microscopic observation showed that the Gus(+)Kan(R) strains colonized the rhizoplane, seed coat, and phylloplane of creeping bentgrass. These results supported our earlier observation that strain 1295-22 was rhizosphere and phyllo-plane competent. Interactions between T. harzianum and R. solani were readily observed in situ and changed over time. Two types of reactions were found in these experiments. In the first type, sections of hyphae of R. solani near the hyphae of T. harzianum appeared damaged, and the pathogen appeared necrotic when viewed with a microscope. The second type, observed less frequently than the first type, was typical of myco-parasitism. The findings in this study provide new insight into the interactions between R. solani and T. harzianum, providing a basis for future research.