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1.
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   

2.
The toxicities, to a laboratory susceptible strain and to a resistant strain of Oryzaephilus surinamensis (L.), of water-dispersible powder formulations of pirimiphos-methyl, fenitrothion or chlorpyrifos-methyl under constant conditions of 25°C and 70% r. h. were compared to the toxicities when the insects were exposed to a diurnal cycle of 12.5–20–12.5°C and 70–50–70% r. h. to simulate grain store conditions in the UK during spring and autumn. All the insecticides were more effective at 25°C and 70% r. h. The LD50 values for the susceptible strain were low, being 4.4 and 1.4 mg m?2 at 12.5-20°C and 25°C, respectively, for chlorpyrifos-methyl, 18.3 and 4.1 mg m?2, respectively, for pirimiphos-methyl, and 4.0 and < 1.O mg m?2, respectively, for fenitrothion. The LD50 values obtained from the two sets of environmental conditions for a resistant strain (484) differed by factors of 1.8 for chlorpyrifos-methyl, 4.8 for pirimiphos-methyl, and 7.3 for fenitrothion. Toxicity studies were also made with chlorpyrifos-methyl under various constant conditions of temperature and humidity from 5–30°C (5°C intervals) and 30, 50, 70 and 90% r. h., and also at O°C and 60% r. h. Chlorpyrifos-methyl was very effective and there was little or no cross resistance to chlorpyrifos-methyl in the resistant strain. From 15 to 30°C, mortality was high, and differences in mortality at the LD50 level for the various humidities were slight, but there was a decrease in mortality with decreasing humidity at any one temperature, in particular, at 5°C, 50 and 70% r. h., and 10°C and 50% r. h. Chlorpyrifosmethyl was more toxic to both strains at the highest humidity (90%) throughout the whole temperature range. The LD50 values for each strain decreased at each temperature as the water vapour concentration was increased. At O°C and 60% r. h., all the insects from both strains died but the cause of death was not clear.  相似文献   

3.
The effects of low-volume ventilation on the persistence and biological efficacy of chlorpyrifos-methyl applied to English wheat were investigated. Four 20-tonne batches of wheat were treated with a dose of 2.5 mg kg?1 chlorpyrifos-methyl. After treatment, two of the batches were aerated continuously at a rate of 17 m3 h?1 tonne?1 (10 cfm tonne?1) for 16 weeks. The remaining two batches were not aerated. Samples were collected from both aerated and non-aerated wheat at intervals over the 16-week storage period and subjected to biological assay using laboratory multi-organophosphorus-resistant strains of Tribolium castaneum, Sitophilus granarius, Sitophilus oryzae and Oryzaephilus surinamensis. The samples were also analysed for chlorpyrifos-methyl residues. No differences in either the biological efficacy or the rate of chemical decomposition were detected between the aerated and non-aerated wheat.  相似文献   

4.
A simple method for multi-residue analysis of pesticides by low-pressure gas chromatography-tandem mass spectrometry (LP-GC-MS-MS) has been validated in compost samples. The pesticide residues were extracted from the lyophilised samples with organic solvent by stirring. No sample clean-up was required prior to the analysis. The method was applied to determine the fate of two organochlorine pesticides (lindane and endosulfan) and two organophosphates (malathion and chlorpyrifos-methyl) during the composting process in the reactor of a pilot plant. Malathion, chlorpyrifos-methyl and lindane residues almost fully disappeared after 8 days of maturation in the reactor, while endosulfan residues were only partially degraded. Alongside this, a study of natural disappearance of the pesticides was carried out in the laboratory and a characteristic time profile was traced for each pesticide class.  相似文献   

5.
The combined efficacy of spinosad and chlorpyrifos-methyl was determined against four storage psocid pests belonging to genus Liposcelis. This research was undertaken because of the increasing importance of these psocids in stored grain and the problem of finding grain protectants to control resistant strains. Firstly, mortality and reproduction were determined for adults exposed to wheat freshly treated with either spinosad (0.5 and 1 mg kg(-1)) or chlorpyrifos-methyl (2.5, 5 and 10 mg kg(-1)) or combinations of spinosad and chlorpyrifos-methyl at 30 degrees C and 70% RH. There were significant effects of application rate of spinosad and chlorpyrifos-methyl, both individually and in combination, on adult mortality and progeny reduction of all four psocids. Liposcelis bostrychophila Badonnel and L. decolor (Pearman) responded similarly, with incomplete control of adults and progeny at both doses of spinosad but complete control in all chlorpyrifos-methyl and combined treatments. In L. entomophila (Enderlein) and L. paeta Pearman, however, complete control of adults and progeny was only achieved in the combined treatments, with the exception of spinosad 0.5 mg kg(-1) plus chlorpyrifos-methyl 2.5 mg kg(-1) against L. entomophila. Next, combinations of spinosad (0.5 and 1 mg kg(-1)) and chlorpyrifos-methyl (2.5, 5 and 10 mg kg(-1)) in bioassays after 0, 1.5 and 3 months storage of treated wheat were evaluated. The best treatment was 1 mg kg(-1) of spinosad plus 10 mg kg(-1) of chlorpyrifos-methyl, providing up to 3 months of protection against infestations of all four Liposcelis spp. on wheat.  相似文献   

6.
The residues of [14C] chlorpyrifos-methyl remaining in wheat after solvent extraction accounted for 28% of the applied dose after an extended period of storage. A bioassay of these residues was carried out using Tribolium castaneum and a significant reduction in the numbers of adults reaching maturity was observed. Attempts to release the non-solvent-extractable residues using an enzymic digestion procedure were unsuccessful, as were several of the chemical solubilisation procedures investigated. A water/methanol extraction system was successful in releasing up to 86% of the radioactivity leaving 10% still non-extractable. Analysis of this solubilised residue revealed that 59% was present as the pyridinol metabolite of chlorpyrifos-methyl and 26% was a polar material composed of two main components. Bioassay tests of these metabolites revealed that the reduction in the number of insects reaching maturity could be associated with the pyridinol metabolite.  相似文献   

7.
A European-wide project has been undertaken to establish the potential for dissipation of atrazine in the soil subsurface environment. Samples were obtained, avoiding contamination, in four countries (Belgium, Greece, Hungary and UK) and laboratory studies carried out. In order to make comparisons between results from each laboratory, a ring experiment was carried out using common methodology for sampling, extraction and analytical techniques. Subsurface materials from each country were distributed to the other countries. Atrazine dissipation was determined in each country for all materials under the same laboratory conditions. The results of this comparative study showed generally good agreement between all laboratories. Significant potential microbiological dissipation was detected in certain samples. Where differences occurred between laboratories this was attributed to small, spatially heterogeneous microbial populations in the subsurface materials. © 1997 SCI.  相似文献   

8.
The accuracy and reproducibility of analytical methods for the assay of five organophosphorus grain protectants have been investigated by a coordinated test programme. Results were assessed using data from field applications of chlorpyrifos-methyl, fenitrothion, malathion, methacrifos and pirimofos-methyl at commercial silos in New South Wales and Queensland. A satisfactory analytical procedure is recommended following an extended series of tests.  相似文献   

9.
Field trials with various pesticide combinations were carried out on bulk wheat in commercial silos in Queensland, South Australia and Western Australia. Laboratory bioassays on samples of treated grain at intervals over 8 months using malathion-susceptible and malathion-resistant strains established the following orders of efficacy: against Sitophilus oryzae (L.), chlorpyrifos-methyl 10 mg kg?1 + bioresmethrin 1 mg kg?1 = methacrifos 15 mg kg?1 in aerated storage > pirimiphos-methyl 4 or 6 mg kg?1 + bioresmethrin 1 mg kg?1 = bioresmethrin 4 mg kg?1 + piperonyl butoxide 16 mg kg?1; against Rhyzopertha dominica (F.), bioresmethrin 4 mg kg?1 + piperonyl butoxide 16 mg kg?1 > methacrifos 15 mg kg?1 > chlorpyrifos-methyl 10 mg kg?1 + bioresmethrin 1 mg kg?1 = pirimiphos-methyl 4 or 6 mg kg?1 + bioresmethrin 1 mg kg?1. All treatments completely prevented production of progeny in Sitophilus granarius (L.), Tribolium castaneum (Herbst), T. confusum Jackquelin du Val and Oryzaephilus surinamensis (L.). The biological efficacy of methacrifos was greater and the rate of degradation lower in aerated than in non-aerated storage. Residue levels of all compounds were determined chemically and were below proposed international residue levels to be considered by the Codex Alimentarius Commission.  相似文献   

10.
The degradation of [14C]pirimiphos-methyl was investigated on a 1-kg bulk of grain stored in the laboratory at 15°C for 28 weeks. Breakdown of pirimiphos-methyl was slow, leaving 77% of the applied dose unchanged at the end of the experiment. The major degradation product was the hydroxypyrimidine (up to 12.5% of the applied dose) with the remainder of the residue (up to 12.1%) remaining within the grain tissues after solvent extraction. The efficacy of the treatment was assessed in a parallel experiment by bioassay of a 5-kg bulk of grain dosed with unlabelled pirimiphos-methyl. 100% Mortality of an organophosphateresistant strain of Oryzaephilus surinamensis L. was maintained throughout the experiment whereas some survival of an organophosphate-resistant strain of Tribolium castanewm (Herbst) occurred after 12 weeks of storage. This increased to give a 20% survival rate at the end of the experiment.  相似文献   

11.
Trials were carried out over two consecutive years to compare the efficacy of chlorpyrifos-methyl, etrimfos, fenitrothion and pirimiphos-methyl against susceptible and organophosphorus-resistant strains of Tribolium castaneum Herbst, Sitophilus granarius L. and Oryzaephilus surinamensis L., gamma-HCH-resistant strains of Acarus siro L. and Glycyphagus destructor Schrank, and a susceptible strain of Tyrophagus longior Ger-vais. Pirimiphos-methyl was not evaluated against the three mite species as data on the efficacy of this material had previously been published. Etrimfos and pirimiphos-methyl were also tested against a susceptible and an organophosphorus-resistant strain of Sitophilus oryzae L. Each pesticide was applied to two separate 20-tonne batches of English wheat and stored under ambient conditions for 36 weeks. The efficacy of the pesticides was assessed regularly over the storage period using established bioassay techniques. However, chlorpyrifos-methyl and fenitrothion were assessed against susceptible and resistant strains of S. granarius for 32 weeks only. Each of the four pesticides produced >95% mortality of the susceptible strain of all insect species tested for the entire duration of the trial with the exception of fenitrothion, when survival of T. castaneum increased after 32 weeks. Only fenitrothion failed to give 100% mortality of the resistant strain of S. granarius throughout the trial, but even so, the mortality was always >95%. Chlorpyrifos-methyl, etrimfos and pirimiphos-methyl gave much better control of the resistant T. castaneum than fenitrothion, and etrimfos gave slightly better control of resistant O. surinamensis than pirimiphos-methyl which was in turn better than chlorpyrifos-methyl at 36 weeks. Both etrimfos and pirimiphos-methyl gave 100% mortality of the susceptible and resistant strains of S. oryzae. None of the pesticides maintained 100% kill of A. siro throughout the trial and fenitrothion failed to achieve this level of mortality after only 4 weeks. Etrimfos produced 100% mortality of the other two mites species tested throughout the trial, whereas both chlorpyrifos-methyl and fenitrothion achieved this level of mortality for 32 weeks.  相似文献   

12.
An investigation into the extraction of dichlorvos from stored grain and satisfactory storage conditions for samples received for analysis has been carried out using [32P]-dichlorvos. It has been shown that samples can be effectively stored at —17° C and that methanol can be used for the extractable dichlorvos but does not remove the organophosphorus residue bound to the grain.  相似文献   

13.
Residues of gamma-HCH and chlorpyrifos-methyl in Ponderosa pine bark (Pinus ponderosa Laws.) were determined 7-300 days after spray treatment, by a rapid extraction method using ethyl acetate and sodium sulphate, and analysis by gasliquid chromatography using either an electron-capture or nitrogen-phosphorus detector. The residue data were fitted into a power curve equation, Y = axb, to determine the rates of insecticide disappearance. The half-life values (μg cm?2), as interpolated from the power curve, indicate that 50% disappearance occurred in 43 (± 9) days for gamma-HCH and 102 (± 26) days for chlorpyrifos-methyl. When half-life values, however, are computed from extrapolated initial deposits, 50% disappearance occurred in 6 (± 1) days for gamma-HCH and 15 (±4) days for chlorpyrifos-methyl.  相似文献   

14.
以甜玉米金玉甜1号为试验材料,于吐丝期叶面喷施胺鲜酯(DTA-6),研究其对甜玉米叶片光合特征、籽粒粒重、糖分积累、光合作用关键酶磷酸烯醇式丙酮酸羧化酶(PEPCase)和核酮糖二磷酸羧化酶(Ru BPCase)及蔗糖代谢相关酶蔗糖磷酸化酶(SPS)和蔗糖合成酶(SS)活性动态变化的调控效应。结果表明:DTA-6处理显著提高了甜玉米籽粒灌浆期穗位叶叶绿素含量和光合速率,改善了PEPCase和Ru BPCase的活性;DTA-6处理显著促进了籽粒SPS和SS活性表达,处理后12 d籽粒中可溶性糖、蔗糖和淀粉含量比对照分别增加了8.4%、8.8%和8.9%;DTA-6处理显著促进了籽粒灌浆速率,提高了穗粒数和粒重,增加了产量,其中鲜穗产量、穗粒数和千粒重比对照分别增加了15.8%、9.6%和11.9%。研究结果证实,DTA-6可以显著改善甜玉米产量和品质形成,为其在甜玉米高产优质栽培中推广应用提供了理论依据。  相似文献   

15.
BACKGROUND: Insect growth regulators are promising alternatives to traditional pesticides in stored grain. The efficacy of the juvenile hormone analogue methoprene was evaluated as a layer treatment in a laboratory experiment for control of Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) in wheat, rice and maize. RESULTS: Adults of R. dominica were placed in vials containing 33, 26 and 29 g (to a depth of 6.5 cm) of wheat, rice and maize, respectively, that was entirely or partially treated with 1, 5 or 10 mg kg?1 methoprene. In wheat and rice, the layer treatments were not as effective as the whole‐grain treatment, but there was decreased progeny production as the application rate increased. However, on maize the partial treatments were as effective as the whole‐grain treatment at 5 and 10 mg kg?1. CONCLUSIONS: The results suggest that partial layer treatments with methoprene can be used to control R. dominica on maize but may not be effective for control of this species on wheat and rice. Copyright © 2011 Society of Chemical Industry  相似文献   

16.
The responses of a highly fenitrothion-resistant and a susceptible strain of Oryzaephilus surinamensis L. from Australia were measured against a range of alternative grain protectants using impregnated-paper and treated-grain assays. The R-strain was also highly resistant to carbaryl, moderately resistant to malathion and pirimiphos-methyl and showed low-level resistance to methacrifos, chlorpyrifos-methyl, bioresmethrin, permethrin, cyfluthrin, cypermethrin and dichlorvos. There was marginal resistance to deltamethrin. Methoprene, to which there was no resistance, was the most effective material at suppressing progeny production of the resistant strain. At current commercial application rates chlorpyrifos-methyl was the only compound of those tested that would completely control both adults and larvae of resistant O. surinamensis for a storage period of nine months. Overall, the homogeneity of response of both strains to insecticides using the treated-grain assay was as good as the response from impregnated-paper assays. The latter also tended to exaggerate resistance factors compared to the treated-grain assays.  相似文献   

17.
Effect of air temperature, rain and drought on hot water weed control   总被引：1，自引：1，他引：1  
The influence of rain and drought before, and air temperature during, weed control with hot water was studied in laboratory experiments on the test weed Sinapis alba (white mustard). The plants were grown in a greenhouse and treated outdoors. There was no difference in weed control effect when S. alba plants at the four‐leaf stage were treated at the air temperatures 7°C and 18°C. The effective energy dose for a 90% fresh weight reduction was 465 kJ m?2 for both air temperatures. Weed control of S. alba at the four‐ to six‐leaf stage in rainfall above the rainwater run‐off level increased the required effective energy dose by 20% (i.e. 120 kJ m?2) compared with dry plants. A short period of drought just before treatment on S. alba at the two‐ to four‐leaf stage increased the plant fresh weight reduction, which was 22% at low energy dose (190 kJ m?2) and 44% at high energy dose (360 kJ m?2). Hot water weed control should thus be carried out when the plants are drought stressed and avoided when the plants are wet. The air temperature seems to be of little importance in the range 7–18°C.  相似文献   

18.
假禾谷镰孢(Fusarium pseudograminearum,Fp)是我国黄淮麦区小麦茎基腐病(Fusarium crown rot of wheat)的优势病原菌,目前该病害呈不断蔓延和为害加重的趋势.本研究从五月中旬小麦灌浆期至玉米收获期,在河南开封和焦作田间调查采集小麦茎基腐病样,对13份小麦茎秆和小麦残茬上...  相似文献   

19.
The effect of metham-sodium on Orobanche aegyptiaca Pers. was tested in the laboratory and in soil columns. The laboratory experiment was carried out on O. aegyptiaca seeds placed in Petri dishes and germinated with GR24, a synthetic strigol analogue. In soil columns, metham-sodium was applied by application of the chemical through the irrigation water to three different soils and its dissipation determined in three soil layers by gas chromatography, by a lettuce bio-assay to check the herbicide's phytotoxicity, and with a flax bioassay to check its effect on O. aegyptiaca. Results of the germination experiments showed an exponential decrease in O. aegyptiaca germination, parallel with the increase of metham-sodium concentration, with an average effective concentration (EC50) of 18 mg L?1. In a soil column, methylisothiocyanate (MIT, the metham active product) rapidly disappeared from the upper soil level (0–10 cm) within 24 h. Seven days after application only traces of MIT remained in all soil layers in all soils, except for the sandy Rehovot soil that contained low concentrations in the lower soil layer (20–30 cm). Flax bioassay confirmed the chemical analysis, showing that O. aegyptiaca tubercles developed only on plants grown in the upper soil layer of all three soils.  相似文献   

20.
In the western part of Japan, two wheat cultivars, Nishinokaori and Minaminokaori, are currently cultivated for breadmaking. Breadmaking wheat requires a higher protein content compared to the Japanese noodle wheat (the major type of wheat in Japan). This high protein level in the grain is obtained by top-dressing with nitrogen (N) near anthesis. Because such N applications may increase levels of Fusarium head blight (FHB) and consequent mycotoxin [deoxynivalenol (DON) and nivalenol (NIV)] accumulation in the grain, the effect of N application (0, 4, and 8 g/m2) at anthesis on FHB and mycotoxin accumulation in Nishinokaori and Minaminokaori was tested in the greenhouse in 2004 and 2005 and in two fields in 2006. In the greenhouse, plants were spray inoculated at 3, 10, and 20 days after N treatment. In field experiments, colonized maize kernels, which generate ascospores during the testing season, served as inoculum. In all experiments for both cultivars, N application at anthesis significantly increased grain protein as expected, but had no significant effect on FHB and DON and NIV levels in grain. These results suggest that, at least in these cultivars, N can be applied close to anthesis without increasing the risk of FHB and mycotoxin (DON and NIV) accumulation.  相似文献   

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