超高效液相色谱-串联质谱法测定番茄中多菌灵及其主要代谢物的残留

建立了同时测定番茄中多菌灵及其主要代谢物(2-氨基苯并咪唑和苯并咪唑)的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法。番茄样品用乙腈超声提取,经浓缩后用初始流动相稀释并定容,过0.22 μm滤膜后进行UPLC-MS/MS分析。采用多反应监测(MRM)模式测定,外标法定量。结果表明:在添加水平为0.05~5 mg/kg下,多菌灵及其主要代谢物的平均回收率为70.5％~104.9％,相对标准偏差为2.6％~9.5%。方法的检出限(LOD)为0.16~4.73 μg/kg,定量限(LOQ)为0.29~4.99 μg/kg。     

Oxidation of diazinon and malathion by myeloperoxidase

The aim of the work was to investigate the in vitro oxidation of diazinon and malathion, organophosphorous pesticides (OPs) containing phosphorthioate group, catalyzed by enzyme myeloperoxidase (MPO). The oxidation was performed in the presence of hydrogen peroxide. The products were identified as oxon derivatives (phosphates), where the sulfur atom from thioate group was substituted by an oxygen atom. No hydrolysis products were detected after enzyme - induced oxidation. The oxidation efficiency was controlled using acethylcholinesterase (AChE) bioassay for determination of oxon derivatives concentration. The influence of OPs concentration, incubation time of OPs with MPO, as well as MPO concentration on the yield of oxo forms was investigated. Kinetic constants of MPO in oxidation of malathion and diazinon were estimated. The maximum concentration of oxo forms was achieved after 10 min incubation of OPs in 50 mM phosphate buffer (pH 6.0) with 100 nM MPO.     

Determination of famoxadone, fenamidone, fenhexamid and iprodione residues in greenhouse tomatoes

BACKGROUND: Greenhouse tomato production is intended exclusively for fresh consumption. Typical greenhouse conditions provide a conducive environment for the development of different fungi, principally late blight and grey mould, that can destroy plants and fruits. For this reason, different fungicides with different sites of action are used in integrated pest management strategies. Famoxadone, fenamidone, fenhexamid and iprodione (fig. 1 ) are fungicides of difference classes with different actions that could be used to control tomato pests. RESULTS: The QuEChERS method showed good recoveries, and the analytical method allowed good separation of the fungicides selected. Good results were obtained in terms of repeatability and intermediate precision, with a coefficient of variation of < 9.8%. The limits of determination and quantification of the method were far below the maximum residual levels (MRLs) set by the EU for these fungicides in tomatoes. The analysis of fungicide residues showed that cv. Shiren accounted for higher residue levels than cv. Caramba. The dissipation curves were similar in the two cultivars, indicating that the decrease in pesticides was not related to the tomato type. CONCLUSIONS: Care should be taken when using pesticides in greenhouse conditions, because degradation mainly affects fruit growth. The size of the tomato, in particular its surface/weight ratio, is very important for defining pesticide residues. All fungicides used showed residue levels below the MRLs at the preharvest interval. Copyright © 2011 Society of Chemical Industry     

Hydrolysis of malathion by rabbit liver oligomeric and monomeric carboxylesterases

The hydrolysis of malation by rabbit liver oligomeric and monomeric carboxylesterases (CE's) (EC 3.1.1.1) results in the formation of a mixture of α- and β-monoacids. A new chromatographic procedure was utilized to investigate the formation of α- and β-monoacids. The oligomeric carboxylesterase (oCE) produced an $\text{α}\text{β}$ ratio of monoacids of 4.55, and the monomeric carboxylesterase (mCE) produced an $\text{α}\text{β}$ ratio of monoacids of 2.33. The ratios of α- and β-monoacids were independent of the initial concentration of malathion and remained constant over the time course of the reaction. Kinetic studies demonstrated that the K_m values were the same for the corresponding reactions which produced either α-monoacid or β-monoacid with the same enzyme. Since both carboxylesterases are electrophoretically pure, the kinetic data strongly supports the theory that the reactions which produced α- and β-monoacids are catalyzed by the same active site. Comparison of the k_cat and K_m values governing the hydrolysis of malathion by the two esterases, together with their relative abundance in liver, indicated that the oCE would be responsible for about 80 to 98% of the hydrolytic detoxication of malathion by rabbit liver.     

General esterase,malathion carboxylesterase,and malathion resistance in Culex tarsalis

The role of esterases in malathion resistance in Culex tarsalis has been investigated. When larvae of a resistant and a sensitive strain were placed in water containing [¹⁴C]malathion, malathion penetrated to give initially similar internal levels. With resistant mosquitoes, after 15 min the internal malathion concentration decreased to low levels while the monoacid degradation products accumulated in the larvae and were excreted into the surrounding water, whereas in susceptible larvae the internal malathion level stayed high and was lethal. It is suggested that the decrease in internal malathion and the resulting resistance were caused by an active malathion carboxylesterase in the resistant strain. A specific assay for malathion carboxylesterase with [¹⁴C]malathion showed 55 times more activity in resistant than in susceptible larvae, whereas when general esterase activity was assayed with α-naphthyl acetate only 1.7 times the activity was found. Analyses by starch gel electrophoresis showed a peak of malathion carboxylesterase, 60-fold higher from resistant than from susceptible larvae, in a gel zone which did not stain for general esterase activity. General esterases that did not hydrolyze malathion showed different electrophoretic patterns in the two populations, which are likely due to the nonisogenic character of the strains. These results show that use of a specific assay and the demonstration of degradation of malathion in vivo are essential for assessment of the contribution of esterase activity to the malathion-resistant phenotype in mosquito populations.     

Potentiation of malathion by other insecticides against Musca domestica

Twenty-seven insecticides, including organochlorine, organophosphorus compounds and carbamates were tried for potentiation of the toxic effect of malathion. Carbaryl, diazinon, fenthion, gamma-BHC, parathion and tetrachlorvinphos potentiated the action of malathion. Fourteen insecticides gave additive effects while seven proved antagonistic. Insecticides which showed potentiation, were further tested by mixing with malathion in the ratios of 1:9, 3:7, 5:5, 7:3 and 9:1. All the five combinations in the six mixtures gave potentiating effects. Maximum potentiation of 17.6 times was observed in 1:9 combination of malathion and gamma-BHC. The proportions in which the insecticides were mixed had a pronounced effect on the toxic effect of malathion.     

Effect of a mixture of iprobenfos and malathion on the development of malathion resistance in the mosquito Culex pipiens pallens Coq

A malathion-resistant (RM) strain of Culex pipiens pallens Coq was obtained by successively selecting a field population with malathion in the laboratory. The synergistic effect of iprobenfos on malathion toxicity and alpha-naphthyl acetate (alpha-NA) esterase assay revealed that malathion resistance in the RM strain was associated with increased alpha-NA esterase activity and the synergism was mainly due to the inhibition by iprobenfos of this activity. There was no difference in alpha-NA esterase activity between the larvae and female adults in the susceptible (S) strain, but the activity in the adults was 13-fold higher than in the larvae of the RM strain. To understand the effect of the application of a mixture of iprobenfos and malathion on the evolution of malathion resistance, an artificial strain (Syn) was generated by mixing the RM and S strains with 0.1 frequency of the malathion-resistant individuals. The offspring of the Syn strain were divided into two sub-strains, Rm and Rm+ibp, which were successively treated with, respectively, malathion alone and malathion + iprobenfos (1:2) at LC70. In the mixture, the fungicide iprobenfos acted as a synergist of malathion. After treatment for 10 generations, the resistance level to malathion was 317.4-fold for the Rm sub-strain, whereas for the Rm+ibp sub-strain it was only 38.9-fold, compared with the Syn strain. Similar results were obtained by measurement of alpha-NA esterase activity from both larvae and female adults. The alpha-NA esterase activities in larvae and female adults at F10 generation were 2.6- and 10.9-fold from the Rm+ibp sub-strain and 5.7- and 98.5-fold from the Rm sub-strain, respectively, compared with the Syn strain. The above results suggested that iprobenfos, although it cannot completely stop or prevent the onset of malathion resistance, could dramatically delay its evolution.     

四种乳酸菌对马拉硫磷的手性选择性降解研究

乳酸菌广泛存在于自然界,为明确其对手性农药马拉硫磷的选择性降解情况,采用CHIRALCEL OD-H手性色谱柱及高效液相色谱分析方法,研究了马拉硫磷对映异构体的拆分以及在植物乳杆菌Lactobacillus plantarum subsp.plantarum、干酪乳杆菌Lactobacillus casei、保加利亚杆...     

Penetration of malathion into locusts

Topically applied dilute solutions of malathion in kerosene extract ‘bottoms’ are more toxic and rapid in action than concentrated ones. Dilute solutions spread farther, penetrate more rapidly and consequently their rate of activation into the more toxic malaoxon is higher. With a single dose of 2·5% malathion the rate of penetration and activation varies according to the loci of topical application, presumably reflecting differences in sclerotisation of the cuticle. There are also inherent differences in the susceptibility of various body regions associated perhaps with the differential vulnerability of some vital internal organ (e.g. the central nervous system). Very rapid hydrolytic degradation of malathion occurs through its conversion into malaoxon; locusts survive the lethal action of malathion by way of such degradation only where activation into malaoxon takes place in areas away from the sensitive head region, or where the rate of activation is slow, or where the circulatory system delays its arrival at such sensitive sites. The higher rate of activation observable in immature adults of Schistocerca gregaria compared with mature adults is, however, counterbalanced by a higher rate of hydrolysis in the former.     

Dispersal of Phytophthora nicotianae on tomatoes grown by nutrient film technique in a greenhouse

Tomatoes were grown in a greenhouse by nutrient film technique (NFT). They were inoculated withPhytophthora nicotianae either by direct inoculation of roots or by adding fungal spores to a container with recirculating nutrient solution. In the first case, the resulting epidemic seemed to be polycyclic, in the second case monocyclic. In both cases, inoculum freely circulated through the NFT system and was present in the nutrient solutions for at least 6 days after inoculation.Samenvatting Kastomaten werden gekweekt met behulp van voedingsfilmtechniek. Zij werden geinoculeerd metPhytophthora nicotianae hetzij door directe besmetting van wortels, hetzij door een sporensuspensie toe te voegen aan het voorraadvat met voedingsoplossing. In het eerste geval leek een polycyclische epidemie te volgen. In het tweede geval ontstond een monomcyclische epidemie. In beide gevallen werd schimmelinoculum door het gehele gotensysteem rondgepompt. Inoculum bleef gedurende tenminste 6 dagen na inoculatie aantoonbaar in de voedingsoplossing.     

Yield of glasshouse tomatoes as affected by strains of tobacco mosaic virus

In the latter part of the summers of 1963, 1964 and 1965 the effect of an early inoculation with different strains of tobacco mosaic virus (TMV) upon yield was investigated. All experiments were carried out in the same glasshouse-compartment and with the tomato variety Moneymaker, the plants being grown in plastic pails containing ordinary potting soil. In 1963 a green strain, a distorting strain and a yellow (or aucuba) strain were used, all capable of causing local lesions onNicotiana tabacum White Burley, which reaction is characteristic for the tomato-type of TMV. Since unfavorable conditions affected control plants more than infected plants, the green strain caused no significant loss of yield. Plants infected by this strain yielded only 3% less weight of fruit than the control plants and even had a 12% greater number of fruits. Plants infected by either the distorting or the yellow strain yielded 43 and 65% respectively less weight of fruit and 32 and 48% respectively fewer fruits. In 1964 the same green strain of the tomato-type TMV was compared with a green strain of the tobacco-type TMV, which is characterized by a systemic reaction on White Burley. Plants infected by the tomato-type and tobacco-type green strains ylelded 16 and 21% respectively less weight of fruit than the control plants and 11 and 18% respectively fewer fruits. In 1965 the same green strain of the tomato-type TMV was used and compared with another green strain of the same virus, which in addition caused local lesions onN. glauca, and with a yellow ringspot strain, which showed the tomato-type reaction on White-Burley. Plants infected with these three strains yielded 14, 18 and 17% respectively less weight of fruit than the control plants, but only 2, 6 and 6% respectively fewer fruits. The relatively small reduction in the number of fruits and an appreciable delay of the harvest probably resulted from the fact that the plants in this experiment were inoculated in the seedling stage.Samenvatting In 1963,1964 en 1965 werd in de nazomer het effect van een vroege inoculatie met verschillende stammen van het tabaksmozalekvirus (TMV) op de opbrengst van tomaat nagegaan. Alle proeven werden uitgevoerd in dezelfde kas en met het tomateras Moneymaker; de planten werden opgekweekt in plastic emmers die met gewone potgrond gevuld waren.In 1963 werden een groene stam, een misvormende stam en een gele (of aucuba-)stam gebruikt, welke alle in staat zijn de voor het tomaattype TMV karakteristieke lokale lesies te veroorzaken opNicotiana tabacum White Burley. Aangezien ongunstige omstandigheden de controleplanten nadeliger beinvloedden dan de ge'infecteerde planten, veroorzaakte de groene stam geen duidelijk opbrengstverlies. Planten, die met deze stam geinfecteerd waren, brachten slechts 3% minder aan vruchtgewicht op dan de controleplanten en zelfs 12% meer vruchten. Planten, geïnfecteerd met de misvormende of met de gele stam, brachten respectievelijk 43 en 65% minder aan vruchtgewicht op en respectievelijk 32 en 48% minder vruchten.In 1964 werd dezelfde groene stam van het tomaattype vergeleken met een groene stam van het tabakstype TMV, welke gekarakteriseerd wordt door een systemische reactie op White Burley. Planten, geïnfecteerd met de groene stam van het tomaattype of tabakstype TMV, brachten respectievelijk 16 en 21% minder aan vruchtgewicht op dan de controleplanten en respectievelijk 11 en 18% minder vruchten.In 1965 werd opnieuw dezelfde groene stam van het tomaattype TMV gebruikt en vergeleken met een andere groene stam van hetzelfde virus, welke bovendien lokale necrotische lesies veroorzaakt opN. glauca, en met een gelekringvlekkenstam, welke eveneens de tomaattype-reactie vertoont op White Burley.Planten, welke met een van deze stammen waren geïnfecteerd, brachten respectievelijk 14, 18 en 17% minder aan vruchtgewicht op dan de controleplanten, maar slechts 2, 6 en 6% minder vruchten. De betrekkelijk geringe reductie in het aantal vruchten en een aanzienlijke oogstverlating waren waarschijnlijk het gevolg van het feit dat de planten in deze proef in het kiemplantstadium waren geïnoculeerd.Stationed at the Glasshouse Crops Research and Experiment Station, Naaldwijk.     

Iodometric analysis and shelf life of malathion in formulations

Using an iodometric method for the determination of malathion in emulsifiable concentrates, values of active ingredient in four commercial formulations and one primary reference standard were within ±0.7% weight/volume (w/v) of the stated concentrations. A standard deviation of 0.42% w/v and 95% confidence limits of ±0.9% w/v for a single determination were calculated for the method. Added moisture and elevated temperature were found to accelerate malathion breakdown in the commercial formulations. The greatest breakdown rate of 5.2% w/v per 100 days occurred with a formulation stored at 27 °C containing 0.5% v/v added moisture.     

The effect of root-knot nematodes and Ethrel on Fusarium wilt of tomatoes

The reaction of two tomato varieties, Moneymaker (susceptible toFusarium) and Fortos (resistant toFusarium) to inoculation withMeloidogyne javanica, M. incognita andFusarium oxysporum f. sp.lycopersici race1 as well as to application of Ethrel (2 chloroethane phosphonic acid)—an ethylene releasing compound—was studied. With Moneymaker, Ethrel reduced wilt symptoms drastically and this was correlated with a reduction in the number of infected vascular bundles in the stem. Height of the stems was increased. Both nematode species counteracted the therapeutic effect of Ethrel by increasing the number of infected vascular bundles. Fortos remained resistant toFusarium in the presence of nematodes and/or Ethrel. Only, a slight tendency toward resistance-breaking by the nematode was observed. In this variety enhancement of the pathogenic effects of the nematodes by Ethrel was evidenced by increased gall size. Histological studies indicated no difference in xylem structure among the various treatments. These results support the evidence that plant growth regulators play a role in the pathogenicity of root-knot nematodes, theFusarium resistance of the plants, and the effect of nematodes on the severity ofFusarium wilt.Samenvatting Bestudeerd werd de reactie, van twee tomatecultivars, Moneymaker (gevoelig voorFusarium) en Fortos (resistent tegenFusarium) op inoculatie metMeloidogyne javanica, M. incognita enFusarium oxysporum f. sp.lycopersici ras 1, en op behandeling met Ethrel (2 chloorethaan fosfonzuur) een verbinding waaruit ethyleen vrijkomt. Bij Moneymaker resulteerde behandeling met Ethrel in een sterke afneming van verwelkingssymptomen gecorreleerd met een vermindering van metFusarium geinfecteerde vaatbundels in de stengel (Fig. 2 en 3) en een grotere lengte van de planten (Fig. 1). Beide aaltjessoorten hadden het omgekeerde effect en verhoogden het aantal metFusarium geïnfecteerde vaatbundels (Fig. 2 en 3).Bij Fortos was er slechts een zeer geringe mate van verlies van resistentie tegenFusarium onder invloed van de aanwezigheid van wortelknobbelaaltjes. Ethrel elimineerde de geringeFusarium infectie geheel. Bij deze cultivar werd het schadelijk effect van de aaltjes duidelijk versterkt door Ethrel in correlatie, met een sterke toeneming van de omvang der gallen (toeneming wortelgewicht, Fig. 4). Ethrel had geen rechtstreeks effect opFusarium in reincultures.Histologische waarnemingen gaven geen aanwijzingen voor het optreden van veranderingen in de structuur van het xyleem (thyllen) onder invloed, van de behandelingen.De resultaten ondersteunen de opvatting dat groeiregulatoren een rol spelen bij de pathogeniteit van wortelknobbelaaltjes, deFusarium-resistentie van de plant, en de invloed van aaltjes op de ontwikkeling van,Fusarium in de plant.     

外源褪黑素对番茄果实品质和挥发性物质的影响

为探究外源褪黑素对番茄果实品质及挥发性物质的影响,以番茄（Solanum lycopersicum）‘航粉高糖’品种为试材,以果实表面喷施蒸馏水为对照（CK）,设4个不同浓度褪黑素喷施果实处理,分别为T1（50 μmol·L^-1）、T2（100 μmol·L^-1）、T3（150 μmol·L^-1）、T4（200 μmol·L^-1）。结果表明：（1）100 μmol·L^-1外源褪黑素处理能显著增加番茄果实中果糖、葡萄糖和可溶性总糖的含量,降低有机酸含量,从而显著提高番茄果实糖酸比。（2）5个处理中共检测出86种挥发性物质,包括12种酮类、32种醛类、14种醇类、4种酯类、13种烃类、7种酚类和4种其他类物质。各处理挥发性物质总数量和总含量依次为：CK（55种,1 279.18 μg·kg^-1）、T1（69种,1 960.95 μg·kg^-1）、T2（66种,2 258.70 μg·kg^-1）、T3（62种,1 818.84 μg·kg^-1）、T4（59种,1 695.04 μg·kg^-1）,均为醛类含量最高,酚类含量最低,其中100 μmol·L^-1处理可提高番茄果实中酮类、醛类、醇类和酯类挥发性物质总含量。检测出的挥发性物质共包含10种番茄特征香气成分,100 μmol·L^-1处理的特征挥发性物质含量最高,为1 307.34 μg·kg^-1。（3）与对照相比,喷施褪黑素提高了番茄果实单果质量以及可溶性固形物、可溶性蛋白、维生素C、番茄红素含量,促进果实对N、K、Mg、Cu、Fe、Zn等矿质元素的吸收。（4）主成分分析表明,各处理的综合得分表现为T2>T1>T3>T4>CK。综上,外源喷施褪黑素可显著提高番茄果实的营养和风味品质,且100 μmol·L^-1浓度效果最佳。     

噻虫胺在番茄和土壤中的残留及消解动态

通过两年3地的田间试验,采用分散固相萃取-液相色谱-串联质谱法,研究了50%噻虫胺水分散粒剂在番茄和土壤中的残留及消解动态。结果表明:在0.005、0.01和0.05 mg/kg添加水平下,噻虫胺在番茄中的回收率为90%～121%,相对标准偏差（RSD）为4.0%～4.5%（n=5）,在土壤中的回收率为88%～92%,RSD为3.6%～5.8%（n=5）,番茄和土壤中噻虫胺的定量限均为0.005 mg/kg,可满足现有限量标准的要求。噻虫胺在番茄中的消解动态符合准一级动力学方程,半衰期为3.5～17.3 d。当50%噻虫胺水分散粒剂以推荐剂量（有效成分）60 g/hm2在番茄生长到成熟个体一半大小时施药3次,施药间隔7 d时,噻虫胺在番茄上的最终残留量在< LOQ～0.32 mg/kg之间,远低于日本规定的最大允许残留量（MRL）值3 mg/kg,推荐采收安全间隔期为1 d。     

The effect of impurities on the toxicokinetics of malathion in rats

The effect of the malathion impurities, isomalathion of O,S,S-trimethyl phosphorodithioate (OSS-Me), on the toxicokinetic behavior of [methoxy-¹⁴C]malathion in female rats was investigated. Malathion α- and β-monoacids and the diacid were the predominant metabolites in the blood of rats pretreated orally with corn oil followed 4 hr later with radiolabeled malathion. Pretreatment of rats with isomalathion or OSS-Me in corn oil followed by treatment with malathion resulted in a decrease of total radioactive metabolites in the blood. Moreover, a substantial reduction in the level of malathion β-monoacid and malathion diacid was observed in the blood of impurity pretreated animals. These results indicate that the impurities have a stronger effect in inhibiting carboxylesterases which preferentially hydrolyze the β-carboethoxy moiety of malathion. The major malathion metabolites excreted in the urine of pretreated and control rats generally matched those present in the blood. The potentiation of the acute toxicity of malathion by pretreatment with isomalathion or OSS-Me may be explained by the reduction in the rat's capacity to degrade malathion via carboxylesterase-catalyzed hydrolysis of the β-carboethoxy moiety.