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1.
Laying hens were treated daily for 14 days with oral doses of [14C-phenoxy]cypermethrin (1.52 mg day?1, 0-7 mg kg?1) formulated on a small quantity of diet. Radioactivity in the eggs reached a plateau value of 0.05 μg equivalents g?1 8 days after the start of dosing. Most of the residue was found in the yolk and was a mixture of cypermethrin and material which was closely associated with neutral lipids and phosphatidyl cholines. Four and a half hours after the last dose, the birds were killed and selected tissues were taken for analysis. The highest residue was found in the liver. This was composed of cypermethrin and a mixture of very polar metabolites which were not hydrolysed to significant amounts of 3-phenoxybenzoic acid or its 4-hydroxy derivative.  相似文献   

2.
Disposition kinetics of cypermethrin and fenvalerate were investigated in lactating black Bengal goats following single dose intravenous administration at 57 and 45 mg kg?1 respectively. The maximum and minimum blood concentrations of cypermethrin were 18.49 (±3.17) and 0.06 (±0.002) μg ml?1, while the corresponding values for fenvalerate were 14.58 (±2.37) and 0.04 (±0.005) μg ml?1 respectively. Both cypermethrin and fenvalerate remained present in blood for 36 h. The mean t1/2β) and Vdarea values were 5.56 (±0.28) h and 10.38 (±2.20) litre kg?1 for cypermethrin and 5.66 (±0.35) h and 11.31 (±2.20) litre kg?1 respectively for fenvalerate. Both cypermethrin and fenvalerate persisted in goat milk for 36 h. The t1/2β) and AUC values of fenvalerate were 7.37 (±1.84) h and 122.38 (±11.65) μg h ml?1 whilst the corresponding values for cypermethrin were 6.66 (±1.54) h and 99.48 (±7.81) μg h ml?1 in milk respectively.  相似文献   

3.
The depletion of zeta‐cypermethrin residues in bovine tissues and milk was studied. Beef cattle were treated three times at 3‐week intervals with 1 ml 10 kg?1 body weight of a 25 g litre?1 or 50 g litre?1 pour‐on formulation (2.5 and 5.0 mg zeta‐cypermethrin kg?1 body weight) or 100 mg kg?1 spray to simulate a likely worst‐case treatment regime. Friesian and Jersey dairy cows were treated once with 2.5 mg zeta‐cypermethrin kg?1 in a pour‐on formulation. Muscle, liver and kidney residue concentrations were generally less than the limit of detection (LOD = 0.01 mg kg?1). Residues in renal‐fat and back‐fat samples from animals treated with 2.5 mg kg?1 all exceeded the limit of quantitation (LOQ = 0.05 mg kg?1), peaking at 10 days after treatment. Only two of five kidney fat samples were above the LOQ after 34 days, but none of the back‐fat samples exceeded the LOQ at 28 days after treatment. Following spray treatments, fat residues were detectable in some animals but were below the LOQ at all sampling intervals. Zeta‐cypermethrin was quantifiable (LOQ = 0.01 mg kg?1) in only one whole‐milk sample from the Friesian cows (0.015 mg kg?1, 2 days after treatment). In whole milk from Jersey cows, the mean concentration of zeta‐cypermethrin peaked 1 day after treatment, at 0.015 mg kg?1, and the highest individual sample concentration was 0.025 mg kg?1 at 3 days after treatment. Residues in milk were not quantifiable beginning 4 days after treatment. The mean concentrations of zeta‐cypermethrin in milk fat from Friesian and Jersey cows peaked two days after treatment at 0.197 mg kg?1 and 0.377 mg kg?1, respectively, and the highest individual sample concentrations were 2 days after treatment at 0.47 mg kg?1 and 0.98 mg kg?1, respectively. © 2001 Society of Chemical Industry  相似文献   

4.
This paper describes the residue analysis of water and hydrosoil samples taken from two separate large-scale aquatic ecotoxicology trials designed to assess the environmental fate and effects of the pyrethroids lambda-cyhalothrin and cypermethrin. Comparison of the results demonstrates the high degree of reproducibility of the chemical residue found the day after treatment using experimental mesocosms (lambda-cyhalothrin) as opposed to an in-use farm pond (cypermethrin). Both studies showed that pyrethroid residues were rapidly lost from the water column: residues of lambda-cyhalothrin were less than 2 ng litre?1 following the final application of a cumulative seasonal exposure equivalent to twelve ?drift’? and six ?run-off’? events, each delivering a dose equivalent to that expected from a typical event under field conditions. Hydrosoil appeared to act as a sink for pyrethroid residues and, under the stringent test conditions of the mesocosm study, lambda-cyhalothrin residues reached 3.2 μg kg?1 following the seasonal exposure described above. The cypermethrin farm-pond study illustrated the localised pattern of exposure expected under natural field conditions, with site topography and cultivation practices which represent an average ?worst case’?. Residues in hydrosoil reached a maximum level of approximately 25 μg kg?1 in one sampling zone at one interval, and thereafter declined to a level of < 9 μg kg?1 within four months.  相似文献   

5.
Foliar applications of synthetic pyrethroids were made to several crops to determine residue levels at various intervals after application. On onions, residues of cypermethrin, permethrin and fenvalerate were negligible > 0.1 mg kg?1, 7 days after application. On lettuce, residues of fenvalerate and permethrin were 0.8 mg kg?1. On celery, residues of fenvalerate did not decline and ranged from 0.12 to 0.25 mg kg?1 during the 14-day period. On green bush-beans, residues of permethrin and cypermethrin did not decline during the 14-day period and ranged from 0.1 to 0.6 mg kg?1. By day 7, residues of cyfluthrin, cypermethrin, deltamethrin, fenvalerate and permethrin on strawberries were less than the acceptable maximum tolerance of 0.1 mg kg?1 with the exception of cypermethrin, applied at the rate of 0.14 kg a.i. ha?1 which gave a residue of 0.14 mg kg?1.  相似文献   

6.
A single dose (4 mg kg?1) of 14 C-labelled (R)-flamprop-methyl to rat was rapidly metabolised and 90% of the dose was eliminated in urine and faeces within 48 h. Four days after dosing, tissue residues were 0–1 μg equivalents g?1 tissue or much less, with the exception of kidney (0–22 μg g?1). There was a statistically significant sex difference in the routes of elimination; this may be attributed to differences in the biliary elimination of the major metabolite, flamprop acid, or its glucuronide conjugate. The fate of racemic flamprop-methyl was very similar to that of the (R)-isomer. The major metabolic routes were hydrolysis of the esters to the corresponding acids, hydroxylation of the benzoyl aromatic rings and conjugation. The flamprop acid derived from the (R)-flamprop-methyl was found to be partially converted to the (S)-form (R:S ratio, 87:13). This reaction is discussed in the context of other such biological racemisations recently reported.  相似文献   

7.
A method is described for the analysis of the herbicide bromoxynil and its octanoate in soils. Following extraction with aqueous acidic acetonitrile, the octanoate was separated from the phenolic bromoxynil by solvent partitioning. The ester and the phenol were assayed by gas-liquid chromatography without further modification or preparation of a derivative. Recoveries in excess of 93% were obtained from soils treated with the phenol and the ester at levels of 0.5 or 0.1 μg g?1. The persistence of bromoxynil octanoate applied at a rate of 3 μg g?1 was studied in the laboratory on a heavy clay and a sandy loam at 85% of field capacity moisture and 20°1°C, both alone and in the presence of 2,4-D (2 μg g?1); MCPA (2 μg g?1); MCPA+asulam (both at 2 μg g?1); and MCPA+difenzoquat (both at 2 μg g?1). In each soil there was a rapid conversion of bromoxynil octanoate to the free phenol, which then underwent a rapid degradation, so that after 7 days, over 90% of the original treatment had disappeared. There appeared to be no effect on bromoxynil breakdown by any of the herbicides added in combination. Small field plots were treated, in early May 1977 and 1978 at two locations in Saskatchewan, with a combination of commercial formulations containing asulam, bromoxynil octanoate, and MCPA at rates of 1 kg ha?1 each. After 10 weeks the plots were sampled and analysis showed that in all cases, no asulam, bromoxynil, or bromoxynil octanoate could be extracted from the top 10 cm of soil.  相似文献   

8.
Chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate] is an organophosphorus insecticide applied to soil to control pests both in agricultural and in urban developments. Typical agricultural soil applications (0.56 to 5.6 kg ha?1) result in initial soil surface residues of 0.3 to 32 μg g?1. In contrast, termiticidal soil barrier treatments, a common urban use pattern, often result in initial soil residues of 1000 μg g?1 or greater. The purpose of the present investigation was to understand better the degradation of chlorpyrifos in soil at termiticidal application rates and factors affecting its behaviour. Therefore, studies with [14C]chlorpyrifos were conducted under a variety of conditions in the laboratory. Initially, the degradation of chlorpyrifos at 1000 μg g?1 initial concentration was examined in five different soils from termite-infested regions (Arizona, Florida, Hawaii, Texas) under standard conditions (25°C, field moisture capacity, darkness). Degradation half-lives in these soils ranged from 175 to 1576 days. The major metabolite formed in chlorpyrifos-treated soils was 3,5,6-trichloro-2-pyrid-inol, which represented up to 61% of applied radiocarbon after 13 months of incubation. Minor quantities of [14C]carbon dioxide (< 5%) and soil-bound residues (? 12%) were also present at that time. Subsequently, a factorial experiment examining chlorpyrifos degradation as affected by initial concentration (10, 100, 1000 μg g?1), soil moisture (field moisture capacity, 1.5 MPa, air dry), and temperature 15, 25, 35°C) was conducted in the two soils which had displayed the most (Texas) and least (Florida) rapid rates of degradation. Chlorpyrifos degradation was significantly retarded at the 1000 μg g?1 rate as compared to the 10 μg g?1 rate. Temperature also had a dramatic effect on degradation rate, which approximately doubled with each 10°C increase in temperature. Results suggest that the extended (3–24 + years) termiticidal efficacy of chlorpyrifos observed in the field may be due both to the high initial concentrations employed (termite LC 50 = 0.2– 2 μg g?1) and the extended persistence which results from employment of these rates. The study also highlights the importance of investigating the behaviour of a pesticide under the diversity of agricultural and urban use scenarios in which it is employed.  相似文献   

9.
Rhizome segments from Alternanthera philoxeroides were shaken in solutions of 14C-glyphosate for 24 h to establish a range of internal tissue concentrations. Rhizomes were killed at concentrations of 16 μg g?1 dry weight and above and survived at concentrations of 8 μg g?1 dry weight and below. Plants grown in the field for 10 weeks in declining photoperiod were used to investigate the uptake and translocation of 14C-glyphosate after application of a constant dosage in either 1.0-or 0.2-μl droplets corresponding to concentrations of 1.06 and 5.3 g 1?1, of glyphosate acid, respectively. Use of smaller droplets of higher concentration increased absorption of 14C, but did not improve translocation. Uptake by treated leaves was 25 and 41% of the applied glyphosate for the large and small droplets respectively, but translocation to underground parts of the plant was about 7% of applied 14C-activity. Radiolabel accumulated in new rhizomes was equivalent to about 0.5 μg g?1 dry weight of glyphosate, at least 30 times below the concentration required for tissue death. Absorption et transport de glyphosate C14 chez Alternanthera philoxeroides (Mart.) Griseb. I.Concentrations dans les rhizomes nécéssaires pour l'inhibition Des fragments de rhizome d'Alternanthera philoxeroides ont été trempés dans des solutions de glyphosate C14 pour aboutir à un éventail de concentrations internes des tissus, Les rhizomes ont été tués à des concentrations de 16 μg g?1 PS et plus, et ont survécu à des concentrations de 8 μg g?1 PS et en-dessous. Des plantes cultivées en plein champ pendant 10 jours en photopériode décroissante ont été utilisées pour étudier l'absorption et le transport du glyphosate C14 après l'application d'une dose constante dans des gouttelettes de 1 ou 0,2 μl correspondant à des concentrations de 1,06 et 5,3 g l?1 de glyphosate C14 acide respectivement, L'utilisation de gouttelettes plus petites de concentrations plus é1evées a augmenté l'absorption du C14, mais n'en a pas amélioré le transport. L'absorption par les feuilles traitées était de 25 et 41% du glyphosate appliqué pour les grandes et les petites gouttelettes respectivement, mais le transport vers les parties souterraines de la plante était d'environ 7% du C14 appliqué. Le radio-marqueur dans les nouveaux rhizomes était équivalent à environ 0,5 μg g?1 PS de glyphosate, soit au moins 30 fois en-dessous de la concentration nécessaire à la mort des tissus. Aufnahme und Translokation von 14C-Glyphosat in Alternanthera philoxeroides (Mart.) Griseb. I. Für die Hemmung erforderliche Konzentration im Rhizom Rhizomteile von Alternanthera philoxeroides wurden 24 Stunden lang in 14C-Glyphosat-Lösungen geschüttelt, um eine Reihe von Konzentrationen in den inneren Geweben einzustellen. Die Rhizome wurden bei Konzen-trationen von 16 und mehr μg g?1 TM abgetötet und überlebten bei Konzentrationen von 8 μg g?1 TM und weniger. Die Aufnahme und Translokation von 14C-Glyphosat nach der Applikation einer konstanten Dosis in 1,0-oder 0,2-μl-Tröpfchen, entsprechend Konzentrationen von 1,06 und 5,3 g l?1 Glyphosat-Säure, wurden an Pflanzen untersucht, die im Freiland 10 Wochen lang bei abnehmender Photoperiode gewachsen waren. Der Gebrauch kleinerer Tropfen höherer Konzentration führte zu mehr Absorption von 14C, förderte aber nicht die Translokation. Das Glyphosat wurde von den behandelten Blättern zu 25 bzw. 41% aus den großen Oder den kleinen Tröpfchen aufgenommen, aber die Translokation in die unterirdischen Pflanzenteile war etwa 7% der ausgebrachten 14C-Aktivität. Die in neuen Rhizomen akkumlierte Radioaktivität entsprach 0,5 μg g?1 TM Glyphosat, mindestens 30mal weniger als für die Abtötung von Gewebe erforderlich.  相似文献   

10.
An analytical method is presented for the analysis of glyphosate and its metabolite (aminomethyl)phosphonic acid (AMPA), in lentil samples. They were extracted from powdered samples with water and chloroform. The aqueous layer was acidified and passed through a cation exchange column. The eluate was made basic, passed through an anion exchange column in the hydroxide form and discarded. The latter column was eluted with hydrochloric acid (0.3 M) which was collected, evaporated under vacuum to 1 ml, diluted with water to 10 ml, filtered and analysed for glyphosate and metabolite using a liquid chromatograph with a post-column reactor and a fluorescence detector. The limit of detection, average recovery and coefficient of variation (CV) were 0.08 μg g?1, 92.5% and 7.3% for glyphosate and 0.1 μg g?1, 92.5% and 8.3% for AMP A. The detector response was found to be linear within the range 20–400 ng.  相似文献   

11.
The persistence of [14C]sethoxydim (2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexene-1-one) at the 2 μg g?1 level was studied under laboratory conditions in three soils at 20°C and 85% of their field capacity moistures. Following extraction of the soils with methanol, the herbicide remaining was determined using radiochemical techniques. Loss of radioactivity was more rapid on moist clay loam and sandy loam, where the half-lives were 12 days, than on heavy clay in which the half-life was 26 days. Loss of radioactivity from air-dried soils (15% of field capacity) was negligible with over 94% of the applied activity being recovered after 28 days. The persistence of sethoxydim at a rate of 1 kg ha?1 was investigated under field conditions using small plots at three prairie locations for 3 successive years. Using an oat-root bioassay procedure, no residues were detected in the 0–10 cm depths of any soils, any year, in September following May treatments.  相似文献   

12.
Pyribenzoxim, benzophenone O‐[2,6‐bis(4,6‐dimethoxypyrimidin‐2‐yloxy)benzoyl]oxime, is a new post‐emergence herbicide providing broad‐spectrum weed control in rice fields. [14C]Pyribenzoxim was used to study the pharmacokinetics of the compound after oral administration of a dose of 1000 mg kg?1 to male Sprague–Dawley rats. The material balance ranged from 97.3 to 99.7% of the administered dose and urinary and fecal recovery accounted for 97.1%, with the majority of radioactivity recovered in feces (88.6%) by 168 h after treatment. Elimination as volatile products or as carbon dioxide was negligible. The following values were obtained for the compound in the blood: AUC0–168h, 28400 µg equiv h g?1; Tmax, 12 h; Cmax, 372 µg equiv g?1; half‐life, 53 h. Radioactivity in tissue decreased from 96.1% of applied radiocarbon at 6 h to 0.4% at 168 h and the highest concentration of radioactivity among the tissues was observed in liver while the lowest residues were found in brain. The elimination half‐lives of radioactivity from tissues was in the range of 7 to 77 h and Tmax values of 12, 24 and 12 h were observed for blood, liver and kidney, respectively. Except for that in the digestive tract, the tissue‐to‐blood ratio (TBR) was highest in the liver. © 2001 Society of Chemical Industry  相似文献   

13.
Methacrifos (22.5 g t?1) and the three protectant combinations chlorpyrifos-methyl (10 g t?1) plus bioresmethrin (1 g t?1), fenitrothion (12 g t?1) plus (1R)-phenothrin (2 g t?1) and pirimiphos-methyl (4 g t?1) plus carbaryl (8 g t?1) were each applied to grain that was stored in at least 15 silos. Grain temperature and levels of protectant were regularly monitored, and samples from 12 storages using each treatment were taken for laboratory assays against Rhyzopertha dominica and Tribolium castaneum. Grain condition did not deteriorate during storage. Grain remained free of insects in 60 of the 63 storages treated; partial failure in the other 3 storages was attributed to low or irregular levels of protectant. The mean and range of residue values of all protectants were recorded as a function of time and the mean observed values corresponded to predicted values. In laboratory bioassay, the order of effectiveness against T. castaneum was methacrifos > chlorpyrifos-methyl plus bioresmethrin > fenitrothion plus (1R)-phenothrin = pirimiphos-methyl plus carbaryl. The order of effectiveness against R. dominica was carbaryl plus pirimiphos-methyl = (1R)-phenothrin plus fenitrothion > methacrifos > bioresmethrin plus chlorpyrifos-methyl.  相似文献   

14.
The disposition of the pyrethroid insecticide cypermethrin, (RS)-a-cyano-3-phenoxybenzyl (1RS)-cis, trans-3-(2,2-dichlorovinly)-2, 2-dimethylcyclopropane-carboxylate, has been studied in male and female rats following a single toxic oral dose (200mg kg−1) of two radiolabelled forms ([14C-benzyl] and [14C-cyclopropyl]) of the insecticide. The bioaccumulation and elimination of 14C-benzyl-labelled cypermethrin, following repeated administration at a sub-toxic dose (2mg kg−1), has also been studied in male and female rats. Although, at the toxic dose, radioactivity from the two radiolabelled forms was rapidly eliminated in urine and faeces, the increased excretion in the faeces, over that for low doses, was evidence that absorption was incomplete. The major pathways of metabolism involved cleavage of the ester bond, with subsequent hydroxylation and glucuronidation of the cyclopropyl acid moieties, together with hydroxylation and sulphation of the 3-phenoxybenzyl moiety. The absence of sex- or dose-dependent changes was reflected by the constant proportions of these metabolites found in the urine. Constant levels of radioactivity in tissues were achieved rapidly, generally within the first week of repeated administration. Elimination was rapid on the cessation of dosing, although less rapid from the fat and skin. The material in the fat was mainly the cis-isomers of cypermethrin, which were eliminated with a mean half-life of 18.2 days, compared with 3.4 days for the trans-isomers.  相似文献   

15.
Duplicate field trials were carried out on bulk wheat in commercial silos in Queensland and New South Wales. Laboratory bioassays on samples of treated grain at intervals over 8 or 9 months storage using malathion-resistant strains of insects established that treatments were generally effective. Cyfluthrin (2 mg kg?1) plus piperonyl butoxide (10 mg kg?1) and cypermethrin (4 mg kg?1) plus piperonyl butoxide (10 mg kg?1) completely controlled two strains of Sitophilus oryzae L. Control of a third strain by the cypermethrin combination was incomplete after 11/2 months and neither controlled a multi-resistant laboratory strain. Both combinations were effective against Rhyzopertha dominica F., Tribolium castaneum Herbst and Ephestia cautella Walker. No natural infestation developed in the treated grain in any silo. Mean residues of cyfluthrin and cypermethrin after 9 months storage were 58% and 52% of the calculated application rates, respectively. Compared with overall concentrations in the wheat, residue levels were higher in bran and pollard and lower in white flour. During baking, residues decreased by up to 29%. Operators experienced respiratory irritation associated with exposure to both combinations and alternative formulations would be required for use of these materials in grain storage.  相似文献   

16.
The uptake and metabolism of DDT, fenitrothion and chlorpyrifos were studied in cultures of the ciliate protozoan Tetrahymena pyriformis. When cultures were treated with DDT in concentrations varying from 0.01 to 0.5 μg ml−1, concentrations found in T. pyriformis were 3.8 to 335 μg g−1 dry weight. The accumulation of fenitrothion ranged from 28.7 μg g−1 in cultures treated with 1 μg ml−1 to 2260 μg g−1 in cultures treated with 10 μg ml−1. Under similar experimental conditions chlorpyrifos was accumulated from 24.7 to 15400 μg g−1. The patterns of uptake were dependent on the growth cycle, the ability of the organism to metabolise insecticide and the type of the insecticide used. Maximum accumulation of DDT, fenitrothion and chlorpyrifos occurred in 2, 4 and 6 h respectively. Tetrahymena metabolised DDT to DDD and DDE but failed to metabolise fenitrothion and chlorpyrifos. The effects on growth and morphology of T. pyriformis were studied over a period of 5 days. Higher concentrations (10, 50 and 100 μg ml−1) of DDT inhibited only the growth of the organisms and did not change cell morphology. Fenitrothion was extremely toxic to the organisms and at 5 and 10 μg ml−1 cells became more or less spherical and died after 48 h. However, concentrations of 0.5, 1 and 2.5 μg ml−1 fenitrothion caused growth inhibition, but only at 2.5 μg ml−1 was this permanent. Chlorpyrifos inhibited the growth of the organisms at 1, 5 and 10 μg ml−1 but the morphology was affected only at 5 and 10 μg ml−1.  相似文献   

17.
The excretion and metabolism of cis + trans-[14C-benzyl] cypermethrin has been compared in quail, rat and mouse. Radioactivity was rapidly eliminated by quail dosed orally with [14C]cypermethrin (2 mg kg?1), as was the case in the rat and the mouse. When the birds were dosed intraperitoneally (IP) with the 14C-labelled pyrethroid, radioactivity was excreted more slowly than after oral dosing, and almost 20% of the IP dose of 14C remained in the tissues after 7 days. Both mammalian species excreted [14C]cypermethrin more rapidly than did the avian species after IP administration, and less than 6% of the dose remained in their tissues after several days. The biotransformation of the pyrethroid was more complex in the avian species (34 metabolites) than in the two mammals (some 10 metabolites in each species). In quail the predominant reactions were ester bond cleavage of cypermethrin together with either aromatic hydroxylation or amino acid conjugation of the 3-phenoxybenzyl moiety. The hydroxylated derivatives were eliminated mainly as sulphates. 3-Phenoxybenzoic acid was conjugated with a variety of amino acids including glycine, taurine, glutamic acid, serine, α-N-acetylornithine and the dipeptide glycylualine. The last two conjugations are unique to avian species. The major metabolite of cypermethrin in the rat was the sulphate conjugate of 3-(14-hydroxyphenoxy)benzoic acid, whereas in the mouse the major products were 3-phenoxybenzoic acid and its taurine conjugate. Thus, in the mammalian species where hydroxylation was maximal, amino acid conjugation was a minor metabolic route und vice versa. However, in the quail, aromatic hydroxylation and amino acid conjugation of the 3-phenoxybenzyl moiety of cypermethrin were both major reactions. The influence of the rates and sites of metabolism, and of the enzymology of amino acid conjugation, in determining this species difference are discussed. The rapid metabolism of cypermethrin to a variety of polar conjugates that are readily excreted, together with the low brain sensitivity of birds compared with mammals to its neurotoxic effects, explains the low acute toxicity of this pyrethoid to avian species.  相似文献   

18.
T. KATAN 《EPPO Bulletin》1985,15(3):371-377
Field isolates of Botrytis cinerea with moderate levels of resistance to dicarboximide fungicides (ED50 1.0–4.9 μg ml?1) and to dicloran were obtained from glasshouses where vinclozolin and iprodione failed to control grey mould. From sensitive and moderatcly-resistant cultures, laboratory isolates were selected on dicarboximide-amended medium, which were highly resistant to these fungicides (ED50 125->3000 μg ml?1). Conidia of all the resistant isolates germinated well on media amended with 100 μg ml?1 of the dicarboximides vinclozolin, iprodione, procymidone and myclozolin and with 5 μg ml?1 of metomeclan. However, the spores of the moderately resistant isolates did not germinate on 100 μg ml?1 metomeclan while the spores of the highly resistant isolates germinated well. Using media with 100 μg ml?1 of metomeclan to distinguish between the two phenotypes, no highly resistant strain was detected among 312 resistant samples from five cucumber glasshouses with a high frequency of moderately resistant strains. From air-borne inoculum of five glasshouses with 100% resistant populations, 1604 colonies were recovered on vinclozolin-amended (100 μg ml?1) medium and none on metomeclan-amended (100 μg ml?1) medium. It is concluded that strains of B. cinerea highly resistant to dicarboximides are absent from field populations.  相似文献   

19.
A simple small-scale method for the determination of fenvalerate residues on cattle hair by gas–liquid chromatography with electron capture detection was developed and applied to the determination of fenvalerate residues from BovaidR ear tags. Recoveries were found to be 96–104% at 10–100 μg g?1 levels of fenvalerate. The minimum detection limit of this method was 1 pg g?1. With one ear tag, fenvalerate was adequately distributed over the entire body and persisted for at least 80 days on the hair of cattle.  相似文献   

20.
Four groups of Indian buffaloes were fed daily with 25 mg of p,p′-DDT p,p′-TDE p,p′-DDE or o,p′-DDT for 100 days. Milk was analysed for organochlorine residues during this period and also for 100 days after pesticide administration had been discontinued. For the period showing ‘plateau level’ residues, 17.2% of p,p′-DDE, 17% of p,p′-TDE, 14% of p,p′-DDT as p,p′-DDT (3.5%); p,p′-TDE (10.5%); 3.2% of p,p′-DDT as o,p′-DDT (1.3%) and o,p'-TDE (1.9%) of their administered amounts were excreted in the milk. Since these compounds were excreted at different rates, the residue levels in the milk expected from a given feed would depend on their concentration and proportional distribution in the feed. The maximum tolerable content of DDT analogues in feed was derived to be 0.1 mg kg?1 (dry weight basis) by using the maximum accumulation coefficient and incorporation of the necessary safety margin. It is concluded that Indian buffaloes fed with rations contaminated with a total of DDT analogues below this limit will yield milk of acceptable quality. Following the termination of feeding with contaminated rations, the elimination of p,p′-DDE in the milk took the longest time and that of o,p′-DDT the shortest. These results suggest that the time required for the initial high residue concentration to decline to less than the legal limit would be determined by the relative amounts of DDE, TDE and DDT in the milk, after elimination of the potent source of contamination.  相似文献   

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