摘要:

AbstractStudies on the mode of action of fixed vegetable oils on Callosobruchus maculatus eggs revealed two possible mechanisms of action which may be complementary: (1) that the oils exert lethal action slowly by drastically reducing respiratory activity and elimination of toxic metabolites as a result of the oil ‘barrier effect’, and (2) direct toxic effects of oil or oil constituents that possibly penetrate the eggs.The slow lethal action of oil was demonstrated by the continuous low level respiratory activity (measured by carbon dioxide emission) of dying eggs over a six‐day monitoring period, and the fact that a significantly higher proportion of the dead eggs found on groundnut or traditional coconut oiltreated grains developed up to the late embryonic stage (first instar larvae) when compared with the control. Furthermore, in an experiment carried out by trapping C. maculatus eggs on oil‐treated and untreated artificial membrane (Sellotape), it was found that oiling did not affect egg development up to the late embryonic stage but prevented hatching of significantly higher numbers of developed first instar larvae.Eggs that successfully hatch on oily grain surfaces may find it more difficult to penetrate, since egg attachments on such surfaces were found to be significantly less secure than on the control.The proposed modes of action show that the complete spread of an oil film over the surfaces of a commodity is vital for the successful utilisation of fixed oils as stored‐product pr

ISSN:0031-613X    

DOI:10.1002/ps.2780260202

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect of organotin compounds on the growth of Ceratocystis ulmi,the causative agent of Dutch elm disease, was studied in shake culture. Triphenyltin, (C6H5)3SnX, tricyclohexyltin, (C6H11)3SnX, and tributyltin, (C4H9)3SnX, compounds were all effective in the inhibition ofC. ulmi in vitro.The anionic group, X, did not play a major role in the inhibitory activities of these compounds, suggesting that the species involved in the inhibition is R3Sn+or the hydrated cation.

ISSN:0031-613X    

DOI:10.1002/ps.2780260203

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe biological activity of the sodium salt of acifluorfen was determined for velvetleaf (Abutilon theophrasti),cocklebur(Xanthium pensylvanicum),morning‐glory(Ipomoeasp.), and soybean(Glycine max) in greenhouse tests and by a leaf‐disc efflux assay which bypasses cuticular penetration. The greenhouse activity in order of decreasing control was morning‐glory>cocklebur>velvetleaf>soybean. Activity in the efflux assay in order of decreasing control was velvetleaf ≈︁ morning‐glory>cocklebur>soybean. Leaf wetting was determined by contact angle measurements. Cocklebur wets very readily, and this was attributed partly to its more polar wax content. Soybean wets very poorly, primarily due to its large leaf hairs, which accounts for part of acifluorfen selectivity. Surfactants and inorganic salts increased penetration in a species‐specific manner, and as penetration increased, so did activity. Acifluorfen‐sodium is more active on velvetleaf than on cocklebur in a leaf‐disc efflux assay, but in the greenhouse the reverse is true. This may be explained by the fact that penetration is eight times greater in cocklebur than in velvetleaf.The chemical composition of the leaf waxes was determined for each species by gas chromatography–mass spectroscopy (GC/MS). Morning‐glory and velvetleaf waxes consist mainly of long‐chain esters. Soybean wax is primarily a C‐30 alcohol. Cocklebur wax is primarily composed of one material which is not a typical leaf wax. This component could not be conclusively identified, but contains several carbonyls, several vinyl groups, and possibly a hydroxyl group. This wax is more polar than the other leaf waxes and seems to account for the extremely good wetting and high degree of penetration in cocklebur compared to the other species. Wax composition does not relate to penetration or activity in the other three species tested. More complex differences in cuticle structure and biological sensitivity probably account for differences in

ISSN:0031-613X    

DOI:10.1002/ps.2780260204

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe ED50values and resistance factors of 20 fungicides that all act as inhibitors of the C‐14 demethylation of 24‐methylenedihydrolanosterol were determined for one wild‐type and four resistant strains ofUstilago avenae.All fungicides were cross‐resistant to each other; however, the resistance factors varied considerably, ranging from 50(triadimenol)to 2·2(miconazole).A tentative structural requirement for low resistant factors was the presence of two phenyl rings separated from each other by at least three atoms. Labeling of lipids with[14C]acetate in the absence and presence of the inhibitors and subsequent sterol analysis revealed that the variable resistance factors were not related to the presence of a second target site. In spite of reported second modes of action of fenarimol, tebuconazole or miconazole, accumulation of C‐14 sterol precursors in both sensitive and resistant isolates was necessary to accomplish growth

ISSN:0031-613X    

DOI:10.1002/ps.2780260205

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe distribution and fate of [14C]carbofuran were studied in model earlyseason rice/fish and late‐season rice/fish ecosystems after its application by respectively soil incorporation and broadcasting. The differences observed in the behaviour of the insecticide in these two rice/fish ecosystems indicated the important effect of the different application methods on the fate of the chemical in the environment. The radioactive residues in the paddy water, rice plants and fish were much lower when the pesticide was incorporated into the soil surface layer. An obvious vertical movement of carbofuran residues occurred in the paddy soil profile. Bound residues constituted the majority of the residues in the paddy soil, rice plants and fish tissues. 3‐Hydroxy‐ and 3‐ketocarbofuran and carbofuran phenol were tentatively identified as the main degradation products in the paddy water, paddy soil, rice plants a

ISSN:0031-613X    

DOI:10.1002/ps.2780260206

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractOff‐target drift and deposition of aerially applied deltamethrin sprays in an agricultural situation were determined using stainless steel (20 × 40 cm)ground deposit samplers and ‘Rotorods’. Off‐target spray deposition decreased exponentially with distance in situations where applications were made in winds with speeds equal to, or just above, maximum label limits for aerial application(8 km h−1).The results are compared with those of previous studies. The effectiveness of a 100‐m ‘no spray’ buffer zone in reducing off‐target de

ISSN:0031-613X    

DOI:10.1002/ps.2780260207

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPartition coefficients of organophosphorus and organochlorine insecticides were determined in several types of membrane. Insecticide partitioning varied among the membranes under study, depending on temperature, cholesterol content and on the physico‐chemical profiles of membrane components and the insecticides themselves. The maximal partitions for DDT, lindane, parathion and malathion in egg phosphatidylcholine bilayers over the temperature range from 10 to 37°C (at which the lipid is in the liquid‐crystalline state)were about 260000, 2000, 1000 and 120, respectively. Incorporation of 50 mol% cholesterol in egg phosphatidylcholine bilayers dramatically decreased the partition and almost abolished the temperature effect. First‐order phase transitions of dimyristoyl‐, dipalmitoyl‐ and distearoylphosphatidylcholines(DMPC, DPPC and DSPC)were accompanied by a sharp increase in insecticide partition. Furthermore, the insecticides under study were more easily accommodated in bilayers of short‐aliphatic‐chain lipids, since higher values of partition were obtained in DMPC bilayers. Partition values in native membranes depended considerably on the membrane type and composition and were higher in sarcoplasmic reticulum(SR) and mitochondria than in brain microsomes, myelin and erythrocytes. Identical results were obtained in related liposomes of total extracted lipids, although the absolute partitions showed decreased values. In general, the incorporation of insecticides correlated reasonably with the cholesterol content of the membranes. The order of partitioning of the above insecticides did not run parallel with their toxicity to mammals and, both in model and in native membranes, followed the sequence: DDT ≫ lindane>par

ISSN:0031-613X    

DOI:10.1002/ps.2780260208

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractIsolate 840905 of Cladosporium cucumerinum,when grown on agar or in liqiud medium, was sensitive to triadimenol, HWG 1608(tebuconazole),fenpropimorph and pimaricin but relatively resistant to terbinafine. Conversely, isolate 49628 was sensitive to terbinafine but relatively resistant to the other fungicides. Changes in sterol composition following treatment with the fungicides reflected the known modes of action of each fungicide. When individual enantiomers of triadimenol were tested against isolate 840905 the order of activity in reducing mycelial growth was 1S,2R>1R,2R>1R,2S ≈︁1S,2S, and this was paralleled by the depletion of ergosterol and the appearance of 14α‐methyl sterols. Isolate 49628 had a greater saturated:unsaturated fatty acid ratio than did isolate 840905 but no major changes in fatty acid composition of either isolate were induced by fungicide treatment. There appears to be no obvious explanation for the differences in fungicide sensitivity of the isolates in terms of their lipid compos

ISSN:0031-613X    

DOI:10.1002/ps.2780260209

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPhotolysis of quinalphos, O,O‐diethylO‐(quinoxalin‐2‐yl)phosphorothioate(I),in ethanolic solutions yields two products, O,O‐diethylO‐(3‐ethoxy‐quinoxalin‐2‐yl)phosphorothioate(II)andO,O‐diethylO‐(3‐(1‐hydroxyethyl)‐quinoxalin‐2‐yl)phosphorothioate(III). Both products derive from the reaction of photo‐excited quinalphos molecule with the solvent. The reactions follow first‐order kinetics. A mechanism that accounts for the formation of the

ISSN:0031-613X    

DOI:10.1002/ps.2780260210

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractSynthesis of a wide range of analogues of the lead compound, N‐2‐methylpropyl‐6‐phenylhexa‐2,4‐dienamide, in which phenyl was replaced by other aromatic systems is reported. In cases where rearrangement rendered theN‐2‐methylpropyl compound less accessible, N‐2,2‐dimethylpropyl substitution was used, because rearrangement was then suppressed. Several of the groups examined, for instance 2‐naphthyl, enhanced insecticidal activity, and when appropriately substituted, particularly with halogen, led to the most active compounds disc

ISSN:0031-613X    

DOI:10.1002/ps.2780260211

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY