溴甲烷、环氧乙烷分解破坏效应研究

溴甲烷和环氧乙烷是常用的杀虫灭菌的熏蒸剂。操作环境中的允许量,按照我国工业企业设计卫生标准(试行)溴甲烷为1毫克/立方米,环氧乙烷为5毫克/立方米。联合国粮农组织资料,每星期五天,每天工作8小时,最高允许浓度溴甲烷20ppm,环氧乙烷50ppm。因此,熏蒸设备的残余气体善后处理问题需研究解决。按照实际操作,箱体内经两次进空气抽气,最后进空气开箱,气相色谱分析结果,溴甲烷用量高达135克/立方米,未发现有残存;环氧乙烷用量高达200克/立方米,残存也只有0.2—1.0ppm,远低于卫生规定的标准。1976—1977年研究处理溴甲烷和环氧乙烷尾气得出:溴甲烷在氧化铜催化条件下,每秒流速0.33升,温度600℃,分解88.4%,625—650℃分解90.1—98.2%,700℃以上分解99.2～100%,温度愈高尾气中溴化氢和溴的含量愈低;5%氢氧化钠酒精溶液,煤油,三乙醇胺、二乙醇、乙醇和氢氧化钠混合液对溴甲烷均有良好的吸收破坏作用。在试制成功的程序控制真空熏蒸机上每立方米用溴甲烷135克测试,碱性酒精溶液吸收破坏96%以上。环氧乙烷室内试验,用热蒸气、蒸馏水、1%硫酸或1%氢氧化钠溶液处理环氧乙烷气体均有良好的水合作用,可生成乙二醇等。在程序控制真空熏蒸机上环氧乙烷每立方米200克测试,自来水淋洗法水合破坏率可达98%以上。     

真空熏蒸室资料

真空熏蒸即在密闭的钢铁制作的熏蒸室内放入货物,抽出绝大部分空气,再施入小量的熏蒸剂。常用的熏蒸剂为溴甲烷或环氧乙烷。环氧乙烷主要用于皮张灭菌(也可兼治害虫)。真空熏蒸较常压熏蒸更有利于毒气在货物内渗透,因此,其熏蒸时间较常压熏蒸处理害虫方面缩短12倍,处理害虫常压熏蒸需要12到24小时,真空熏蒸只要1到2     

溴甲烷、环氧乙烷混用熏蒸处理技术研究

当前熏蒸杀虫技术已较成熟 ,应用药剂主要是溴甲浣 ;熏蒸灭菌则是当前口岸除害处理技术的薄弱环节 ,常使用环氧乙烷。但是高浓度环氧乙烷易燃、易爆 ,不利于口岸熏蒸灭菌处理工作的开展。在研制开发新型、更优良熏蒸剂困难的情况下 ,遇到同时要消毒灭菌和杀虫时 ,合理混用现有的熏蒸剂是一种有益的探索。溴甲烷和环氧乙烷的毒理学研究表明溴甲烷、环氧乙烷混合应用对杀虫效果无负面影响。本研究以溴甲烷常用杀虫剂量为基准 ,结合环氧乙烷的杀菌特长 ,探索较为安全的溴甲烷、环氧乙烷混合熏蒸处理灭菌技术 ,并在口岸病、虫等多类别有害生物的…     

侵染大豆和桑的烟草坏死病毒(TNV)的鉴定

本文主要是介绍农业部植检所和有关单位共同协作进行的应用技术方面的研究结果。杀虫效果方面:室内试验得出:对谷斑皮蠹成虫、幼虫、蛹,温度11～14℃,10克/m~3,处理24～48小时,效果100%。对谷斑皮蠹卵,温度11～14℃,15～50克/m~3,处理24小时,效果9.0～62.5%,50克/m~3处理48小时,40克/m~3处理72小时效果100%,温度20～22℃,40克/m~3处理24小时,15克/m~3处理48小时也100%死亡。对谷象、玉米象、绿豆象的卵,温度20℃,15克/m~3处理48小时效果100%。对胚后期的黑皮蠹、烟草坪,印度谷蛾幼虫、玉米象、谷蠹和绿豆象成虫的效果更好。室外粮垛上试验,粮温15～16℃,50～70克/m~3处理24小时,对玉米象和绿豆象各虫态的效果100%。中草药材垛上试验,温度27～28℃,30克/m~3处理二天,对黑皮蠹幼虫、玉米象各虫态以及锯谷盗成虫效果100%。真空熏蒸,真空度负745～720mmHg,温度12～20℃,70克/m~3处理3小时,对谷象和绿豆象卵的效果方能100%。熏蒸粮食残留量测定结果:20～70克/m~3熏蒸3天,小麦中氟残留量为0.55～1.48ppm,水稻中为0.29～2.48ppm,玉米中为0.09～1.51ppm。熏蒸粉类粮食残留量高。硫酰氟熏蒸粮、棉、油、蔬菜以及林木种籽,对发芽安全。粮食在熏蒸期间对硫酰氟的吸附量,以大豆和玉米为例,分别只有溴甲烷吸附量的36%,20.3%     

溴甲烷、二硫化碳熏蒸处理对苹果蠹蛾的效果及水果安全范围的研究

1984—1986年作者等进行水果熏蒸处理苹果蠹蛾研究,得出溴甲浣、二硫化碳处理苹果(2个品种),梨(6个品种)的熏蒸安全范围及不同温度、不同浓度下的杀虫效果。溴甲烷在15—18℃100％杀虫效果的CT值(浓度×时间)为90;22—24℃为60—70;28—30℃为50。二硫化碳在15—18℃为600;22—23℃为520;28—30℃为300。处理苹果、梨的残留量的分析研究得出,用40克/米~3溴甲烷处理4小时,80克/米~3二硫化碳处理6小时,散气12小时,只在皮层发现溴甲烷残留0.07—0.09ppm,二硫化碳0.15—0.16ppm。果肉内均未检出这两种熏蒸剂的存在。在熏蒸处理安全范围内处理的水果,其味道无不良影响。     

利用气相色谱仪测定环氧乙烷熏蒸浓度

环氧乙烷作为熏蒸剂,已广泛应用于圆筒仓循环熏蒸杀灭谷物中的害虫,以及动植物检疫中动植物产品的消毒灭菌处理。在熏蒸杀虫灭菌处理中,对熏蒸空间的毒气浓度变化和熏蒸后残留于工作场所空气中为害人体健康的毒气浓度进行快速、准确的分析测定是十分必要的。由于环氧乙烷的易燃易爆性,在使用中常和二氧化碳或有机卤素化合物如氟利昂等混     

环氧乙烷熏蒸小麦矮腥黑粉菌应用技术的研究

应用环氧乙烷熏蒸进口小麦矮腥黑粉菌取代干热灭菌法获得成功,为进口小麦灭菌处理开辟了新的途径。试验表明环氧乙烷熏蒸小麦矮腥黑粉菌的有效剂量为175—200克/米~3,熏蒸期间粮温15—25℃,密闭熏蒸3—5天。同时还对矮腥黑粉菌有一定的持续效果。每立方米用150—200克的环氧乙烷熏蒸小麦,对种子的生活力有影响,不宜用于少量引种繁殖材料的熏蒸,只能作进口小麦灭菌处理。     

利用CO2灭菌杀虫的初步研究

在研究草灰水浸种防病,探讨杀菌原理的过程中,发现水浸灭菌与CO_2有关。随着利用CO_2处理接种有散、腥黑穗病菌的小麦种子,获得良好的灭菌效果。将种子预浸5～6小时后,通CO_2密封处理4～6天,对小麦散黑穗病灭菌效果为97.98～100%;对小麦腥黑穗病灭菌效果为91.22%。为进一步验证,又利用CO_2作杀虫试验,亦获得良好的杀虫效果。通CO_2密封处理4～6天,对玉米象杀死率为93.15～100%;对锯谷盗为99.75～100%;对赤拟谷盗为98.55～100%。据多次试验,其灭菌杀虫效果与处理时间、温度成正比。利用CO_2杀虫,在美国已有报道,但是利用CO_2灭菌,迄今尚未见报道。试验证明,利用CO_2灭菌,必须事先将种子进行冷水预浸5～6小时,促使病菌呈萌动状态。否则效果不好乃至无效     

甲酸乙酯对三种主要仓储害虫的熏蒸作用

为明确甲酸乙酯对仓储害虫的实际控制效果,避免二氧化碳对熏蒸作用的影响,该研究利用循环熏蒸系统(FTFS),测定甲酸乙酯对米象、赤拟谷盗、谷蠹三种主要仓储害虫混合虫态的熏蒸作用.结果表明:在25℃、70%RH条件下,甲酸乙酯43.34、80.72、99.08、117.74、146.49mg/L 熏蒸处理6 h,对赤拟谷盗和谷蠹混合虫态有很好的控制作用,死亡率大于95.96%;甲酸乙酯80.72、99.08、117.74、146.49mg/L处理对米象混合虫态的杀虫效果较好.甲酸乙酯对米象蛹的杀虫效果较差.     

溴甲烷减压熏蒸出口白蒜效果好

1988年8月,我们以溴甲烷熏蒸一批57t 的徐州白蒜(受同仓堆放的嘉定白蒜感染咖啡豆象),采用减压措施,效果好于常压熏蒸。该批白蒜装瓦楞纸箱,有通气孔。堆垛糊封后,先开启320～420w 的抽气泵6分钟,聚乙烯帐幕收缩后贴住堆垛表面,后投溴甲烷9.35kg,浓度为48.4g/m~3,帐内温度32～33.5℃,密闭3小时。散气后即将全部虫样取走。于散气后2个半小时检查一批虫样:(1)谷蠹,赤拟谷盗成、幼虫,长角扁谷盗,姬拟谷盗等仓虫共27头,全部死亡;(2)     

Fumigation of gypsophila flowers against Liriomyza trifolii1

Gypsophila cut flowers were fumigated with methyl bromide against Liriomyza trifolii. Complete control was obtained at a dose of 40 g/m³ methyl bromide, for 3 h at 15–18°C. To get satisfactory results without injuring the flowers they had to be conditioned at the above temperature for 6 h prior to fumigation.     

Induction of glutathione S-transterase by fumigants in larvae of the Khapra beetle,Trogoderma granarium (E.)

The effect of fumigants on glutathione and glutathione S-transferase in the Khapra beetle larvae (Trogoderma granarium) was studied by fumigating for 1, 3, and 5 hr with a dose causing 100% mortality at 24 hr of exposure. Glutathione and glutathione S-transferase were assayed in the cytosol at 1, 3, and 5 hr of exposure. Time-dependent depletion of glutathione was seen for all fumigants except carbon tetrachloride and phosphine. The depletion was maximum (60–70%) in the cases of methyl bromide, methyl iodide, and acrylonitrile, and least (20–30%) in the cases of ethylene dibromide and ethylene oxide. The order of glutathione depletion by various fumigants at 5 hr exposure was methyl iodide > methyl bromide = acrylonitrile > ethylene dichloride > ethylene oxide > ethylene dibromide. Glutathione S-transferase was induced by all fumigants except ethylene dibromide, methyl bromide being more potent than methyl iodide. The enzyme induction ranged from 186% by acrylonitrile to 40% by carbon tetrachloride. Mortality above 10% correlated well with the degree of GSH depletion (r = 0.729) whereas the latter did not correlate with the transferase induction.     

Residues in apples and sweet cherries after methyl bromide fumigation

Methyl bromide fumigations are used to treat apples, Malus domestica Borkh, and sweet cherries, Prunus avium (L), before export to Japan. In order to expand existing markets, additional cultivars are being prepared for export to Japan. As part of the approval process, residue analyses must be conducted and residues must be at acceptable levels. Five apple cultivars (‘Braeburn,’ ‘Fuji,’ ‘Gala,’ ‘Jonagold,’ and ‘Granny Smith’) were fumigated at 40 g m⁻³ for 2 h at 10 °C, and six sweet cherry cultivars (‘Brooks,’ ‘Garnet,’ ‘Lapin,’ ‘Rainier,’ ‘Sweetheart,’ and ‘Tulare’) were fumigated for 2 h with 64 g m⁻³ at 6 °C, 48 g m⁻³ at 12 °C, 40 g m⁻³ at 17 °C, and 32 g m⁻³ at 22 °C. Three replicates of fruit from each fumigation were analyzed for methyl bromide and bromide ion residues periodically with time. Methyl bromide residues for both apples and cherries were the highest immediately after fumigation, but rapidly declined so that only ‘Braeburn’ had residues >8 µg kg⁻¹ after 13 days and, except for ‘Lapin,’ all cherries were <1 µg kg⁻¹ after seven days. Average bromide ion residues were between 3.3 and 4.9 mg kg⁻¹ among apple cultivars, and between 3.7 and 8.0 µg kg⁻¹ among cherry cultivars. Published in 2000 for SCI by John Wiley & Sons, Ltd     

Development of a fumigation treatment of oak logs against Ceratocystis fagacearum1

European veneer manufacturers depend greatly on oak imports from the USA. To prevent the accidental introduction of the American oak wilt disease (Ceratocystis fagacearum) into the member states of the European Community, a disinfection treatment was developed for oak logs with respect to the special demands of the veneer industry. Laboratory experiments and field trials in Europe and the USA showed that the fungus can be eradicated from large oak logs with bark attached, by a fumigation with 240 g methyl bromide/m³ applied for 3 days at temperatures of 3°C or above.     

Fumigant doses for the control of Trogoderma granarium1

The diapausing larvae of Trogoderma granarium are among the most tolerant of all storage pests to fumigation and effective dosage schedules are required. For this purpose, the toxicity of methyl bromide (MeBr), phosphine, methyl chloroform (MC), ethylene dichloride (EDC) and chlorobromomethane, and of mixtures of MeBr and MC, EDC and MC, and phosphine and MeBr, to diapausing larvae of the pest was examined at 15, 20 or 25°C. At 15 and 20°C the tolerance of larvae was high and very high dosages of MeBr or liquid fumigants, or long exposures to phosphine, were required for total kill. At 25°C larvae were more susceptible to phosphine but retained a high tolerance of other fumigants. A mixture of 2% MeBr in MC showed evidence of potentiation at 25°C and achieved control of larvae at moderate dosages.     

In-transit control of Liriomyza trifolii in chrysanthemum cuttings1

Individual cuttings and leaves of chrysanthemum infested with eggs and larvae of the alien leaf miner Liriomyza trifolii (Burgess) and batches of pupae, were treated in the laboratory in order to find an effective quarantine treatment to control the pest in imported cuttings. Cold treatment for 2 days at 1–2°C followed by methyl bromide fumigation at 15°C with a range of concentration time products (CTPs) was used to obtain accurate dose-response lines and estimate the LD99 and LD99.9 for each stage of the insect. The largest estimates of the LD99 for eggs, larvae and pupae up to 3 days old were less than the CTP specified in the existing (as at September 1983) United Kingdom statutory fumigation treatment designed to prevent the entry of Spodoptera littoralis (Boisd.). This statutory schedule for unrooted cuttings consists of cold storage for 2 days at 1–2°C and then fumigation with methyl bromide at a CTP of not less than 54 g·h/m³ with a minimum treatment period of 4 h at a minimum air temperature of 15°C. Our results indicate that the Spodoptera treatment should give high levels of kill for most stages of L. trifolii provided a CTP of 54 g·h/m³ and a temperature of 15°C (throughout the fumigation) arc achieved uniformly within packs of cuttings when they are fumigated in their transit boxes in commercial practice. The practicality of the technique will depend on whether it is possible to achieve this without causing unacceptable phytotoxicity. The LD99 values for pupae more than 3 days old were greater than those for eggs, larvae and young pupae. Therefore, if this treatment were adopted as a quarantine measure against L. trifolii, good prophylactic treatments and rigorous prc-packing inspections in exporting countries would still need to be maintained, to minimize any risk of importing pupae. The results are presented in full by Mortimer E.A. & Powell, D.F. (1984). Development of a combined cold storage and methyl bromide fumigation treatment to control the American serpentine leaf miner Liriomyza trifolii (Diptera: Agromyzidae) in imported chrysanthemum cuttings. Annals of Applied Biology 105 , (3), 443–454.     

Effectiveness and profitability of the <Emphasis Type="Italic">Mi</Emphasis>-resistant tomatoes to control root-knot nematodes

Experiments were conducted to determine the effectiveness and profitability of the Mi-resistance gene in tomato in suppressing populations of Meloidogyne javanica in a plastic-house with a natural infestation of the nematode. Experiments were also conducted to test for virulence and durability of the resistance. Monika (Mi-gene resistant) and Durinta (susceptible) tomato cultivars were cropped for three consecutive seasons in non-fumigated or in soil fumigated with methyl bromide at 75 g m^–2 and at a cost of 2.44 euros m^–2. Nematode densities were determined at the beginning and end of each crop. Yield was assessed in eight plants per plot weekly for 6 weeks. The P_f/P_i values were 0.28 and 21.6 after three crops of resistant or susceptible cultivars, respectively. Growth of resistant as opposed to susceptible tomato cultivars in non-fumigated soil increased profits by 30,000 euros ha^–1. The resistant Monika in non-fumigated soil yielded similarly (P > 0.05) to the susceptible Durinta in methyl bromide fumigated soil but the resistant tomato provided a benefit of 8800 euros ha^–1 over the susceptible one because of the cost of fumigation. Selection for virulence did not occur, although the nematode population subjected to the resistant cultivar for three consecutive seasons produced four times more eggs than the population on the susceptible one. Such a difference was also shown when the resistant cultivar was subjected to high continuous inoculum pressure for 14 weeks. The Mi-resistance gene can be an effective and economic alternative to methyl bromide in plastic-houses infested with root-knot nematodes, but should be used in an integrated management context to preserve its durability and prevent the selection of virulent populations due to variability in isolate reproduction and environmental conditions.     

Evaluation of methyl iodide as a soil fumigant in container and small field plot studies

Methyl iodide was evaluated as a soil fumigant as a potential replacement for the widely used soil fumigant methyl bromide. In container trials, methyl iodide was significantly more effective than methyl bromide against the plant parasitic nematodes Meloidogyne incognita, Heterodera schachtii and Tylenchulus semipenetrans and the plant pathogenic fungus Rhizoctonia solani. In small field plots, soil populations of root-knot nematodes were no longer detected after methyl iodide fumigation at an application rate of 112 kg ha^-1. However, after growing a susceptible lima bean host for two months, substantial root-knot galling occurred, while Rhizobium nodulation was absent. At 168 kg ha^-1 of methyl iodide, root-knot galling was reduced to less than 1%, and no Pythium propagules were recovered on selective detection media. These efficacy data support the conclusion that methyl iodide is a likely candidate for replacing methyl bromide as a soil fumigant. © 1998 SCI.     

Influence of plastic mulching and disinfection on the fungal flora of soils in Belgium1

Plastic mulching was tested in Belgium over several years as a method for modifying the population of pathogens and saprophytic fungi in the soil, both in the glasshouse and in the field. The plastic film was kept on the soil for 3 or 6 months, and treatments with formaldehyde, methyl bromide or dazomet were also applied. In the glasshouse the fungal flora was decreased after 6 months’plastic cover without disinfectants, especially for Mucor and Rhizoctonia, but Trichoderma was favoured. The plastic layer together with formaldehyde resulted in 50% killing of soil fungi. In the field with plastic layer only, there was a slight decrease in some fungi and an average increase in bacteria. With plastic combined with formaldehyde (250 ml m^-2), methyl bromide (100 gm^-2) or dazomet (80 g m^-2), better results were obtained. Fungi were reduced 75% with formaldehyde and 80–100% with methyl bromide or dazomet depending on soil depth. Qualitatively there was a clear shift towards Trichoderma, while pathogenic fungi such as Verticillium and Fusarium were nearly 100% killed.     

硫酰氟——溴甲烷土壤消毒潜在的替代品

初步试验表明,硫酰氟25~50 g/m2对土壤真菌(Fusarium sp.)、线虫均有良好的杀灭效果,防治后番茄产量与使用溴甲烷50 g/m2相当。硫酰氟蒸汽压高,穿透性强,可杀死深土层中的线虫及病原菌。由于其在常温下是气体,即使在冬天使用,也不需要搭小拱棚或采用"热法"施药,因此比使用溴甲烷更为方便;使用时也不像威百亩那样需要专用的施药设备。因此,硫酰氟是溴甲烷土壤消毒很有前景的替代品。