The use of entomopathogenic fungi for the control of stored-grain insects

The present contribution discusses the recent advances in the biological control of stored-grain insects with entomopathogenic fungi (EF). Thus, the effect of formulated vs. unformulated strains of EF and the effect of combinations of EF with other components, i.e. diatomaceous earths (DEs), chemical insecticides, natural products and natural enemies against stored-product insects are reviewed. Very few formulations of EF strains have been developed and used, of which invert emulsion formulation (water-in-oil type) is considered the most important. A synergistic effect of EF is produced by combining them with DEs, chemical insecticides and natural products but not with natural enemies belonging to arthropods. Moreover, since the action of EF against insect pests in general, and stored-grain insects in particular, is compatible with the food safety and environmental regulations, a good perspective for these biocontrol agents is expected as alternatives to synthetic insecticides. The potential areas of future research on the effective use of EF as biocontrol agents of stored-grain insects and the constraints that are associated with the registration and commercialization of EF as biopesticides under storage conditions are also discussed. Suggestions for the possible ways for implementation of this technology in storage systems are also provided in the present study.     

The Prospects of Tissue Culture and Genetic Engineering for Strawberry Improvement

Abstract

Strawberry shoot meristem cultures have been used for producing virus-free strawberry plants. Plantlet regneration from leaf mesophyll protoplasts, and Agrobacterium tumefaciens mediated genetic transformation, mark the beginning of strawberry improvement with biotechnologies. The use of biotechnological tools has a greater potential in producing strawberry plants with traits such as early maturation, frost and disease resistance, mite and nematode resistance, high yield, better quality, suitability for mechanical harvesting, shipping ability, ellgaic acid content, aroma compounds and cost-effective micropropagation. Gene identification and mapping with RFLPs or RAPDs would be desirable. Transgenic strawberries should be tested for their quality before releasing to the consumers.     

奔驰W220型空气悬架系统分析

对奔驰W 220型空气悬架系统的结构、功能、工作原理进行分析,阐述了该悬架通过电脑接受传感器的信号并经处理后,由电脑控制执行机构以实现对气体、液体的控制,从而改变悬架刚度和阻尼,以满足车辆在不同道路状况下行驶对舒适性、操控性和通过性的要求。     

铁路货车电能收集装置的机械结构设计

针对转K6型转向架,设计了一种适用于铁路货车的低成本、利用自身能量发电,满足铁路货车低功率用电需求的供电装置。此装置利用滚珠丝杠将悬挂系统的上下振动转变为发电机转子的旋转。通过分析弹簧中的空间以及货车运行过程中的振动情况,设计了滚珠丝杠、外壳等零件,并通过SolidWorks软件对装置进行了仿真。     

硫横苯丁锡混合悬浮剂中苯丁锡含量的测定

本文介绍样品用二氯甲烷提取后，经薄层分离去除干扰，用硫酸 硝酸 过氧化氢消化，使苯丁锡转化成四价锡，以邻苯二酚紫-N-溴代十六烷基吡啶作显色剂，在波长660nm处进行比色测定，其标准偏差为0.04445，变异系数为0.87%，重现性好，方法平均回收率为99.61%。     

Metabolism of [ring-2,6-14]parathion in plant cell suspension cultures of carrot (Daucus carota), purple foxglove (Digitalis purpurea), soybean,thorn apple (Datura stramonium) and wheat (Triticum aestivum)

By means of standardized procedures, the metabolism of [ring-2,6-¹⁴C]-parathion was investigated in carrot (Daucus carota L.), purple foxglove (Digitalis purpurea L.), soybean (Glycine max Merrill cv. ?Mandarin’?, and Glycine max Merrill cv. ?Harosoy 63’? cultivated on B5 and Miller media, respectively), thorn apple (Datura stramonium L.), and wheat (Triticum aestivum L.) cell suspension cultures. In the wheat and soybean (Mandarin) cells only 2.9 and 8.9%, respectively, of the applied parthion remained unmetabolized after 48 h of incubation, while 51.2, 57.9, 60.3, and 62.4% of the unchanged parent were detected in the D. purpurea, D. Stramonium, carrot and soybean (Harosoy) cultures, respectively. In all suspensions, paraoxon and 4-nitrophenol were found as phase I metabolites, thus demonstrating that plant tissues can catalyse oxidative desulfuration and dearylation of parathion. 4-Nitrophenol was also glycosylated with glucose and possibly galactose. Further, as yet unidentified, metabolites indicated that bio-transformations had also occurred at the aromatic moiety. Large amounts of non-extractable residues were detected in the wheat suspension (38.3%), while the other cultures showed a lower incorporation of ¹⁴C into insoluble cell material (0.9-9.4%). For a prospective ecotoxicological evaluation of the metabolic fate of pesticides and xenobiotics in plants in general, the differential metabolic capacity of plant cell cultures and plants should be taken into account.     

Cytogenetic analysis of a long-term Triticum timopheevii (Zhuk.) Zhuk. cell suspension culture

In vitro culturing of plant cells can cause changes in karyotype. Chromosome variations following long-term propagation in suspension culture of Triticum timopheevii (Zhuk.) Zhuk. were studied by routine staining and C-banding. The culture was highly heterogeneous with respect to the number and structure of chromosomes. The modal class cells had a lower chromosome number than T. timopheevii (2n= 28). This data was confirmed by cytophotometric analysis of nuclear-DNA content. Frequencies of chromosome loss varied for different homoeologous groups. A^t genome chromosomes tended to be preferentially eliminated in cells of different ploidy levels. Deletions, insertions, translocations, telocentric chromosomes, isochromosomes and dicentrics and their derivatives were observed in cultured cells. Chromosomes of various homoeologous groups differed in the frequencies and spectra of re—arrangements, but most aberrations occurred in the G-genome chromosomes. In vitro chromosome modifications did not correspond to in vivo variation. Presumably, this difference was caused by differences in the mechanisms of adaptation to the environment at the levels of the cell and the whole organism. G-genome chromosomes were more frequently involved in this process, both in vivo and in vitro.     

Phylogenetic analysis based on ITS sequences and conditions affecting the type of conidial germination of Bipolaris oryzae

One taxonomic characteristic of Bipolaris species is the bipolar germination of conidia, but conidia of Bipolaris oryzae , the causal pathogen of brown spot in rice, are regularly observed to show intercalary germination, a characteristic of Drechslera species. The effect of selection, culture media and culture age on type of conidial germination was determined for three brown spot isolates from Cavinti, San Pablo and Palawan in the Philippines, obtained from infected leaves showing typical disease symptoms. Based on the analyses of their ITS1, ITS2 and 5·8S rDNA nucleotide sequences, the local isolates were clearly identified as B. oryzae . Selection for colonies of the three isolates derived from single conidia with either bipolar or intercalary germination had no effect on the number of spores showing bipolar germination in subsequent cultures. Germination on seven different culture media was tested; of these, rabbit food agar and water agar increased the percentage of bipolar germination of conidia, although this varied between isolates. Incubation of the cultures of all three isolates for longer periods prior to harvesting conidia increased the percentage of bipolar-germinating conidia from c . 40 to c . 90% with 5-day-old and 30-day-old cultures, respectively.     

Isolation and Identification of a Variant Porcine Epidemic Diarrhea Virus and the Immune Efficacy of Its Inactivated Vaccine

This study was aimed to isolate a mutant strain of porcine epidemic diarrhea virus and prepare a PEDV inactivated vaccine with high valence by suspension culture process for immunizing against PEDV effectively in China.200 small intestines and theirs contents of diarrhea piglets died of diarrhea,collected from many large-scale pig farms in China,were detected by RT-PCR and sequenced,a mutant strain of porcine epidemic diarrhea virus was selected and put on the suspension-cultured Vero cells in a 2 L reactor for virus isolation and continuous cell culture,the harvested virus suspension,which was identified and determined TCID₅₀,was inactivated by formaldehyde and mixed with aluminum hydroxide gel adjuvant to prepare PEDV inactivated vaccine.After its physical behavior,stability viscosity,sterility test were checked out,the safety and immune efficacy were studied by immunizing the pregnant pigs and theirs piglets.The results were as follows:86 samples were detected positive in 200 samples,cytopathy occurred after the mutant strain samples screened were passaged to 5th generation,the virus suspension was harvested in 10th generation and identified as a mutant strain of PEDV,named PEDV-GF10 strain.The virus titer of harvested virus suspension was measured up to 1×10^8.0 TCID₅₀/mL after concentrated.After the vaccine was checked out,the sows,40 and 25 days before delivery in experimental groups,were injected into Xuehai acupoint with 4 mL vaccine and the pigs in blank group were free of immunifications.The results showed that there were no obvious differences in the production status of the sows in experimental groups and blank group and the temperature of theirs 3-day-old healthy piglets injected different doses of vaccine,and the vaccine was safe to the sows and piglets.Forty 3-day-old piglets producted by pregnant sows in experimental groups and blank group were randomly selected and taken 4 mL 1×10^8.0TCID₅₀/mL F10 virus culture.The PEDV morbidity of piglets in blank group was 100% after injection and the antibodies were negative;10% piglets in blank group had mild diarrhea symptoms,the protection rate was up to 90%,antibody of passive immunity in piglets lasted for more than 35 days.Virus titer of mutant strain of PEDV-GF10 improved a lot by suspension cell culture,the PEDV-GF10 inactivated vaccine was safe,and could effectively prevent and control the variation strain of PEDV in China.