A chromogenic column for determining phosphine in air

A 1% solution of mercuric chloride in 0.1% cresol red in ethanol, impregnated onto celite and filled into a glass tube [17.8 cm × 0.2 cm (i.d.)] could accurately determine even 0.06 μg phosphine in air. The samples were injected quickly through a rubber septum cap on the glass tubes under low suction. A red coloured band developed instantaneously, the length being proportional to the concentration of phosphine. A calibration curve was prepared with known concentrations of phosphine. The concentrations present in a fumigation chamber were determined and compared with concurrent chemical analysis. There was close agreement between the two methods. A 1:3 and 1:6 mixture of phosphine and ammonia produced two bands, a yellow ammonia band preceding the red phosphine band. However, ammonia interfered with the proper development of the phosphine band.     

Rapid evaluation of phosphine permeability through various flexible films and coated fabrics

Phosphine permeability through forty-one different flexible films and coated fabrics including polyethylene, cellophane, polyvinyl chloride, rubber and cellulose was tested using a sensitive indicator strip. It diffused through all of them; the rate of diffusion, however, varied among them. Four, namely 0.53 mm thick high molecular weight polyethylene, 0.07 mm thick wax paper laminated with polyethylene, 0.23 mm thick unsupported polyvinyl chloride and 0.44 mm thick polyvinyl chloride treated cloth coated with aluminium paint on the cloth side, were the least permeable. Proper screening of commercially available polymer films before their use for fumigation is emphasised. The discussion of the results attempts to rank the films or laminates on the basis of their relative permeability of phosphine. The physicochemical principles of permeability and rapid evaluation method for assessing the performance of flexible film barriers are also discussed.     

Metabolism of tetramethrin in houseflies and rats in vitro

Degradation of radiolabeled tetramethrin or 3,4,5,6-tetrahydrophthalimidomethyl dl-trans chrysanthemumate was tested in vitro by using abdomens of SK, lab-em-7-em, R_HOKOTA and P_y strains of houseflies and rat liver. The effect of NADH₂ and NADPH₂ on the metabolism of tetramethrin by housefly abdomen homogenate was slight, but phosphorothioates, their oxygen analogs, carbamate insecticides, NIA 16388, p-chloromercuribenzoic acid, and mercuric chloride showed marked inhibition. The enzyme activity was localized mainly in the microsomal fraction, where the major metabolites were 3,4,5,6-tetrahydrophthalimide (TPI) (a nonenzymatic reaction from N-(hydroxymethyl) 3,4,5,6-tetrahydrophthalimide, MTI) and chrysanthemumic acid. Smaller amounts of oxidized tetramethrins and chrysanthemumic acid were also produced. The cleavage of tetramethrin into MTI and chrysanthemumic acid was inhibited by such compounds as paraoxon, carbaryl, PCMB, NIA16388, and mercuric chloride. NADPH₂ or NADPH₂ plus carbon monoxide produced little effect. Similar results were obtained with rat liver microsomal fraction. It is presumed from the above findings that the cleavage is catalyzed either by a carboxyesterase or a hydrolase, and that some pyrethroids are metabolized in insects primarily through hydrolytic pathways. Metabolites from oxidative pathways (as in mammals) are formed in minor quantities.     

An evaluation of impregnated respirator canister carbons for phosphine removal from air

The following gas mask canister carbon fillings were evaluated in laboratory and man tests against phosphine which is finding favour as a fumigant for food stuffs: activated carbons impregnated with (1) copper sulphate, (2) potassium dichromate and silver chromate, (3) copper carbonate, potassium chromate and silver chromate and (4) potassium permanganate. Impregnation with copper sulphate (12% w/w) proved to be effective and economical. A cumulative service time of 5.2 mg h/litre was obtained in the laboratory tests at 1.7 mg/litre phosphine in air and 3.1 mg h/litre at 0.2-1.5 mg/litre phosphine in the man tests.     

Improved multiple rapid immunofilter paper assay to detect three viruses of cucumber simultaneously

We improved a multiple rapid immunofilter paper assay (multi-RIPA) to simultaneously detect three major viruses of cucumber, Cucumber mosaic virus, Melon yellow spot virus and Zucchini yellow mosaic virus. When we increased the concentration of bovine serum albumin (BSA) in the extraction buffer, a positive band for each virus developed in the multi-RIPA, regardless of the order that the three sensitized white latex particles were immobilized on the strip. The increase in BSA concentration also strengthened the sensitivity of each RIPA. In addition, using a mixture of commercially available, red and blue, sensitized latex solutions as a tracer, purple bands could be produced on the strips. Because each virus yielded an unique color for a positive reaction, the three viruses were easy to distinguish.     

有機汞粉剂防治馬鈴薯晚疫病試驗

 两年来用有机汞消石灰混合粉防治馬鈴薯晚疫病的田間試驗获得了显著的效果。在发生中心病株时开始用1:9西力生消石灰或賽力散消石灰每7天撒佈1次,共撒4-5次可以大大地抑制病害的蔓延,从而提高产量。西力生和賽力散的防病效果相近。     

The toxicity of phosphine,methyl bromide, 1,1,1-trichloroethane and carbon dioxide alone and as mixtures to the pupae of red flour beetle,Tribolium castaneum herbst

The toxicity of phosphine, methyl bromide, 1,1,1-trichloroethane (methyl chloroform) and carbon dioxide and mixtures of phosphine + methyl bromide, methyl bromide + methyl chloroform, phosphine + carbon dioxide, and methyl bromide + carbon dioxide to one- to two-day-old pupae of Tribolium castaneum Herbst was studied. Joint action ratios estimated at LD₅₀ and LD₉₀ for a 24-h exposure indicated no enhancement of toxicity for mixtures of phosphine and methyl bromide, or methyl chloroform and methyl bromide on the pupae. Carbon dioxide up to 40% in air enhanced the toxic action of phosphine as well as of methyl bromide. Higher levels of carbon dioxide, however, failed to improve the toxicity of phosphine or methyl bromide proportionately. Carbon dioxide used alone produced a maximum of 11% mortality of the pupae exposed to 10–70% levels for 24 h. The order of toxicity of the fumigants both at LD₅₀ and LD₉₀ was phosphine > methyl bromide > methyl chloroform.     

两种指示剂对松材线虫病病木的测试

 通过两种指示剂对不同类型疫区、非疫区病、健木以及不同试样类型的测试表明:0.04%溴酚兰酒精溶液对松材线虫病(Bursaphelenchus xylophilus)的检疫检验,准确率可达85%以上;0.04%二甲基黄酒精溶液(pH=2)只达60%,效果较差。检验时所取试样,无论是木段的横断面还是木屑均可。此外,两种指示剂均不能区分松材线虫病死木和有松天牛(Monochamus alternatus)、拟松材线虫(B.mucronatus)分布的病死木。利用指示剂进行松材线虫病快速检验已获初步成效,但推广应用尚待深入研究。     

磷化氢和溴甲烷复合熏蒸红心火龙果携带番石榴实蝇技术研究

本文研究了磷化氢(PH₃)和溴甲烷(MB)复合熏蒸对番石榴实蝇的毒力以及对红心火龙果采后品质的影响。结果表明,复合熏蒸方式下,各个浓度的磷化氢和溴甲烷均存在增效,当溴甲烷浓度为4 g/m³时,复合熏蒸发挥最佳增效效果的磷化氢浓度为1.42 g/m³。复合熏蒸番石榴实蝇仅需13.19 g/m³的溴甲烷即可在95%置信区间下达到致死率99.996 8%。与对照相比,复合熏蒸对火龙果的外观和内部品质无显著影响,而与溴甲烷单独熏蒸相比,复合处理会显著降低呼吸强度并减少药害。因此,溴甲烷和磷化氢复合处理对番石榴实蝇具有协同效应,表明磷化氢和溴甲烷复合熏蒸有可能成为水果采后处理的一种新策略。     

Ethyl formate plus methyl isothiocyanate--a potential liquid fumigant for stored grains

BACKGROUND: Methyl bromide is being phased out for use on stored commodities, as it is listed as an ozone‐depleting substance, and phosphine is the fumigant widely used on grains. However, phosphine resistance occurs worldwide, and phosphine fumigation requires a long exposure period and temperatures of > 15 °C. There is an urgent requirement for the development of a fumigant that kills insects quickly and for phosphine resistance management. This paper reports on a new fumigant formulation of 95% ethyl formate plus 5% methyl isothiocyanate as an alternative fumigant for stored grains. RESULTS: The formulation is stable for at least 4 months of storage at 45 °C. A laboratory bioassay with the formulation showed that it controlled all stages of Sitophilus oryzae (L.), Sitophilus granarius (L.), Tribolium castaneum (Herbst), Rhyzopertha dominica (F.), Trogoderma variabile Ballion and Callosobruchus maculatus (Fabricius) in infested wheat, barley, oats and peas at 80 mg L^?1 for 5 days, and in canola at both 40 mg L^?1 for 5 days and 80 mg L^?1 for 2 days at 25 ± 2 °C. After an 8–14 day holding period, residues of ethyl formate and methyl isothiocyanate in wheat, barley, peas and canola were below the experimental permit levels of 1.0 and 0.1 mg kg^?1. However, fumigated oats needed an 18 day holding period. CONCLUSIONS: The findings suggest that the ethyl formate plus methyl isothiocyanate formulation has potential as a fumigant for the control of stored‐grain insect pests in various commodities. Copyright © 2011 Society of Chemical Industry     

Triphenyl and tetraphenyl derivatives of group V elements as inhibitors of growth and digestive enzymes of Tribolium confusum and Tribolium castaneum larvae

Tetraphenylstibonium chloride (Ph₄SbCl) at a dietary level of 500–2000 μmol/kg inhibits larval growth, gut invertase activity, pupation, and emergence of Tribolium confusum and Tribolium castaneum. Tetraphenylphosphonium chloride (Ph₄PCl) in this concentration range inhibits growth and gut invertase activity without affecting pupation and emergence whereas tetraphenylarsonium chloride is essentially inactive in all respects. Triphenylstibine (Ph₃Sb) but not the other triphenyl derivatives (amine, phosphine, and arsine) inhibits both larval growth and gut digestive enzyme activities (invertase and protease) in vivo. Protease but not invertase is inhibited in vitro by Ph₄PCl and Ph₄SbCl at 2 × 10^?3M. Ph₄PCl appears to act as an antifeeding agent and Ph₄SbCl and Ph₃Sb as more general toxicants.     

Effects of 22,23-dihydroavermectin B1a on locust (Schistocerca gregaria) muscles may involve several sites of action

Ibotenic acid [2-(3-hydroxyisoxazol-5-yl)glycine] induced a dose-dependent increase in chloride ion conductance in locust muscle fibres which was not sensitive to 4-aminobutyric acid (GABA). This ibotenate response became rapidly desensitised and appeared to be due to activation of extrasynaptic glutamate H receptors. 22-23-Dihydroavermectin B_1a (DHAVM) (500 pg to 1 μg ml^?1) induced irreversible increases in permeability to the chloride ion and abolished ibotenate responses. DHAVM responses were not altered when glutamate H receptors were desensitised by glutamate (1 mM) or ibotenate (100 μM). Irreversible changes in input conductance caused by DHAVM were not affected by penicillin G (1 mM) or bicuculline (1 mM), but picrotoxin (1 mM) and zinc chloride reduced DHAVM responses by 23.7 and 52.6%, respectively. It is concluded that DHAVM has a number of sites of action on locust muscle that include effects on the glutamate H receptor–chloride ion channel complex, in addition to effects on the GABA receptor–chloride ion channel previously described.     

The effect of phosphine on electron transport in mitochondria

The effects of phosphine on electron transport and on some partial reactions of oxidative phosphorylation of mitochondria from mouse liver, housefly flight muscles and granary weevils has been studied. Phosphine was a strong inhibitor of respiration of mitochondria in the “active” state (state 3), uncoupled state, and ion-pumping state on glutamate, pyruvate plus malate, succinate, α-glycerophosphate, and ascorbate-cytochrome c as substrates. Respiration of mitochondria in state 3 was completely inhibited by about 250 μM phosphine. By contrast, the respiration of mitochondria in state 4 was much less sensitive. This inhibition could not be released by uncouplers suggesting that it is due to a direct effect on electron transport. Only site III was inhibited to any significant extent. Kinetic studies show that the inhibition was noncompetitive with Ki ranging from 1.6×10^?5 to 7.2×10^?5 depending on the source and purity of cytochrome oxidase. The inhibition of site III was also more pronounced in sonicated particles than in intact mitochrondria. The significance of this is discussed in relation to membrane sideness and topology of the components of the respiratory chain.Phosphine was unable to activate the “latent” ATPase nor did it have any inhibition of the Mg²⁺-simulated ATPase and only high levels (1.1 mM) showed modest inhibition (41%) of uncoupler-stimulated ATPase. Phosphine had no effect on the ATP-Pi exchange and on the ATP-ADP exchange reaction at concentrations causing strong respiratory inhibition.     

柑桔溃疡病苗化学治疗试验

对柑桔溃疡病苗化学治疗试验结果指出:病苗在1000～2000单位/毫升链霉素+1:100酒精的混合药液中浸1～3小时,便能把病苗治好。处理过的果苗,生长仍然良好。病苗在1:1000～1500的升汞水+1:100酒精的混合药液中1～3小时,也有同样的治疗效果,但苗木生长略差,死亡率略高。用链霉素、升汞水或波尔多液喷射经剪掉病枝叶,或不剪掉病枝叶的病苗,均不能把病苗完全肃清。对柑桔溃疡病的防治,许多国家(如南非、美国等),认为只有毁灭病株,才有可能彻底消灭病原。有时病菌能潜伏数年,如南非有一果园在1918年毁灭病株,1924年重种,当年又发生病害。因此,毁灭病株后,需要连续数年检查,证实无病,才能复种。     

不同基质及颜色背景对井上蛀果斑螟产卵生物学的影响

为明确产卵基质和环境颜色对井上蛀果斑螟成虫产卵生物学特性的影响,在室内条件下,研究了井上蛀果斑螟对PE保鲜膜、硫酸纸、蜡纸3种介质的产卵选择性和绿、橙、红、黄、粉、紫、蓝7种不同颜色背景对成虫寿命、产卵期、产卵量和卵孵化率等生物学参数的影响。结果表明:井上蛀果斑螟在硫酸纸上的累积落卵量最高,对其选择率也最高,分别为130.33粒和58.67%;蜡纸最低,分别为29.00粒和8.00%。绿色背景下雌、雄虫寿命均最短,分别为8.55 d和7.65 d;雌虫寿命在红色背景下、雄虫寿命在黄色背景下最长,分别为15.22 d和15.50 d。粉色背景下雌虫产卵前期较短,为1.50 d,显著短于除绿色背景外的其余处理,红色背景下产卵前期最长,为4.50 d;蓝色背景下雌虫的产卵期最短,为8.25 d,橙色背景下产卵期最长,为17.25 d。粉色背景下雌虫单雌产卵量为73.75粒,显著高于除橙色背景外的其余处理;红色背景下单雌产卵量最少,为28.60粒。绿色背景下卵的发育历期较长,为5.71 d,显著长于除红色和黄色背景外的其余处理;蓝色背景下卵的发育历期较短,为4.66 d。红色背景下卵孵化率较高,为79.53%,其次为紫色背景的79.06%,绿色背景下卵孵化率最低,为54.08%。产卵基质和环境颜色可显著影响井上蛀果斑螟的产卵生物学特性。     

Contact action of diethylstilbestrol (DES)-impregnated paper strips on pregnant Levant voles: Effect of alteration of DES concentration and of total strip area

Placement of paper strips impregnated with a suspension of diethylstilbestrol (DES) in soybean oil into the cage of a pregnant Levant vole (Microtus guentheri [D. & A.]) causes disruption of pregnancy in almost all cases, provided the DES concentration is at least 0.062 mg/cm² and the total area of the strips is at least 100 cm². When the total strip area is 50 cm² or the DES concentration is 0.031 mg/cm², the activity of the strips is markedly reduced.     

从印度进口的洋葱中检出洋葱黄矮病毒

本文报道了从印度进口的洋葱中检出洋葱黄矮病毒。从印度进口的洋葱种球经过隔离试种,有1株洋葱幼苗发生整株矮化,叶片出现无规则的黄色条纹、皱缩等症状,经DAS—ELISA、RT-PCR检测和序列分析验证,确认该批从印度进口的洋葱鳞球茎中携带有洋葱黄矮病毒(Onion yellow dwarfvirus)。     

黄瓜霜霉病菌保存方法

 Pseudoperonospora cubensis(Berk. & M. A. Curtis) Rostovzev, the causal agent of cucumber downy mildew, is an obligate parasitic fungus. Up to now it can not be preserved on culture medium. In this study, the sporangia of P. cubensis were preserved in protective substances of 10% dimethyl sulfoxide plus 5% skim milk, 10% dimethyl sulfoxide plus 10% skim milk, sterilized water and leaves in vitro, and stored at -20℃, -70℃, and preliminary freezing at -20℃ for 24 h prior to -70℃ respectively. The results showed that the sporangia preserved in 10% dimethyl sulfoxide plus 5% skim milk, preliminary freezing at -20℃ for 24 h prior to -70℃ were still highly pathogenic after 12 months preservation. The percentage of germination of sporangia, incidence and disease index were 46%, 50.0% and 40.0 respectively 9 d after inoculation. This method solved the problem of P. cubensis preservation.     

Review A Review of the Mechanisms Involved in the Action of Phosphine as an Insecticide and Phosphine Resistance in Stored-Product Insects

Phosphine gas has been used world-wide for more than four decades as an ideal fumigant for disinfestation of stored grains and other commodities. Its use as a safe fumigant of stored products has become even more important with recent restrictions on the production of the only alternative, methyl bromide. Widespread resistance to phosphine has emerged in several species of stored-product insects in many countries, which in some instances may have caused control failures. Chemically, phosphine is a strong reducing agent and biological redox systems, especially the components of the mitochondrial electron transport chain, are probably the site of its action in insects. The oxidation of phosphine could produce reactive phosphorylating species and interactions of phosphine with biological redox systems have been reported to cause generation of highly reactive oxyradicals. This appears to be the basis of phosphine toxicity to insects, which differs from that of respiratory inhibitors such as hydrogen cyanide. Phosphine-resistant strains of several species of stored-product insects have been reported to absorb very small amounts of the compound compared to their susceptible counterparts. This reduced uptake in resistant insects appears to result from respiratory exclusion of phosphine. The overall mechanism of resistance also involves a detoxification process. Despite the likely involvement of oxyradicals in the insecticidal action of phosphine, the level of anti-oxidant enzymes in resistant insects is apparently not higher than that in their susceptible counterparts. The reduced uptake of the compound might be due either to the presence of a phosphine insensitive target site or to a membrane-based efflux system that excludes phosphine gas in resistant insects. Studies have indicated the oxygen uptake in mitochondrial preparations from susceptible and resistant insects to be equally sensitive to inhibition by phosphine in vitro. The nature of the phosphine-exclusion system in resistant insects has not been fully elucidated. The possibilities of controlling resistant insects with phosphine and prospects for developing new alternative fumigants are also discussed. © 1997 SCI.     

Influence of concentration, temperature and humidity on the toxicity of phosphine to the strongly phosphine-resistant psocid Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)

BACKGROUND: The psocid Liposcelis bostrychophila Badonnel, is a widespread, significant pest of stored commodities, has developed strong resistance to phosphine, the major grain disinfestant. The aim was to develop effective fumigation protocols to control this resistant pest. RESULTS: Time to population extinction of all life stages (TPE) in days was evaluated at a series of phosphine concentrations and temperatures at two relative humidities. Regression analysis showed that temperature, concentration and relative humidity all contributed significantly to describing TPE (P<0.001, R(2)=0.95), with temperature being the dominant variable, accounting for 74.4% of the variation. Irrespective of phosphine concentration, TPE was longer at lower temperatures and high humidity (70% RH) and shorter at higher temperatures and low humidity (55% RH). At any concentration of phosphine, a combination of higher temperature and lower humidity provides the shortest fumigation period to control resistant L. bostrychophila. For example, 19 and 11 days of fumigation are required at 15 degrees C and 70% RH at 0.1 and 1.0 mg L(-1) of phosphine respectively, whereas only 4 and 2 days are required at 35 degrees C and 55% RH for the same respective concentrations. CONCLUSIONS: The developed fumigation protocols will provide industry with flexibility in application of phosphine.