摘要:

AbstractThe adsorption of diuron and isoproturon by a clay loam soil at 35% (3‐16 kPa) and 62% (1 kPa) soil moisture content was studied by means of glass microfibre filters capable of sampling soil solution for herbicide analysis. Adsorption was rapid, with 40–80% of the final (24 h) sorption being achieved within 2 min. These equilibria were achieved more rapidly for diuron, which was also the more highly adsorbed. Adsorption of both herbicides was favoured by low soil moisture initially, but was enhanced by higher soil moistures at sorption times greater than 30 min. However, increasing the soil moisture from 31% (10 kPa) to 62% (1 kPa) had little effect on the final soil sorption capacity. Regarding the water status in the soil, it is thought that adsorption took place in small pores (<3 μm). Herbicides diffused rapidly into small pores and adsorption by wet soil was delayed for a short period of time (about 30

ISSN:0031-613X    

DOI:10.1002/ps.2780450402

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe purpose of this work was to investigate the in‐vivo mode of action of glufosinate in comparison with that of the known glutamine synthetase inhibitor, methionine sulfoxmine, in photoautotrophic microorganisms. Using the eukaryotic green algaChlorella fusca(Shih.&Krauss) and the cyanobacteriumAnacystis nidulans(Kratz&Myers), currently developed [15N]NMR pulselabelling techniques have been employed to study the inhibition of ammonia assimilation. The results show that, while methionine sulfoximine immediately blocks glutamine synthesis, glufosinate action requires an induction process in both organisms investigated, possibly indicating the de‐novo synthesis of an amino acid membrane carrier. In addition, the observed ability ofC. fuscato incorporate nitrogen into glutamate under glutamine synthetase‐inhibiting conditions is explicable by an anabolic function of a glutamate dehydrogenase in this organism. This might explain the large differences in observed species sensitivity to glufosinate exp

ISSN:0031-613X    

DOI:10.1002/ps.2780450403

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAccumulation of tebuconazole by germlings of wild‐type isolates ofBotrytis cinereaPers. ex Fr. was characterized by a high initial level of intracellular tebuconazole during the first 10 min of incubation and a subsequent gradual release of the fungicide into the surrounding medium. This transient accumulation pattern indicates that the efflux of the fungicide has an inducible character. Accumulation of tebuconazole by laboratory‐generated mutants resistant to sterol demethylation inhibitors (DMIs) was significantly less, suggesting that efflux capacity in these mutants is correlated with resistance. Accumulation of tebuconazole by field isolates with a relatively low sensitivity to DMI fungicides was transient in time and accumulation levels did not differ significantly from those of the wild‐type isolates tested. These results suggest that reduced accumulation of tebuconazole in fungal mycelium may account for resistance in laboratory‐generated mutants but not in field isolates ofB. cinereawith a relatively low sensitivity to the fungicide. Various chemicals such as carbonyl cyanide 3‐chlorophenylhydrazone, copper sulfate, fluazinam and BAS 490F enhanced accumulation of tebuconazole by a DMI‐sensitive and a DMI‐resistant isolate. This enhanced accumulation is ascribed to inhibition of the energy‐dependent efflux o

ISSN:0031-613X    

DOI:10.1002/ps.2780450404

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo fungal metabolites, aspyrone (3‐(1,2‐epoxypropyl)‐5‐hydroxy‐6‐methyl‐5,6‐dihydropyran‐2‐one) and asperlactone (3‐(1,2‐epoxypropyl)‐5‐(1‐hydroxyethyl)‐5‐furan‐2‐one) were isolated from anAspergillus ochraceusWilhelm strain showing IGR activity againstTribolium castaneum(Herbst). Synthetic derivatives of aspyrone were produced using published methods. These derivatives together with aspyrone and asperlactone were tested for insect growth‐regulating activity againstT. castaneum, and for ovicidal activity againstNezara viridulaL. Of the compounds tested aspe

ISSN:0031-613X    

DOI:10.1002/ps.2780450405

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractImazapyr absorption, translocation, root release and metabolism were examined in leafy spurge (Euphorbia esulaL.). Leafy spurge plants were propagated from root cuttings and [14C]imazapyr was applied to growth‐chambergrown plants in a water + 28% urea ammonium nitrate + nonionic surfactant solution (98.75 + 1 + 0.25 by volume). Plants were harvested two and eight days after herbicide treatment (DAT) and divided into: treated leaf, stem and leaves above treated leaf, stem and leaves below the treated leaf, crown, root, dormant and elongated adventitious shoot buds. Imazapyr absorption increased from 62.5% 2 DAT to 80.0% 8 DAT. Herbicide translocation out of the treated leaf and accumulation in roots and adventitious shoot buds was apparent 2 DAT. By the end of the eight‐day translocation period only 14% of applied14C remained in the treated leaf, while 17% had translocated into the root system. Elongated and dormant adventitious shoot buds accumulated 3.2‐ and 1.8‐fold more14C, respectively, 8 DAT than did root tissue based on Bq g−1dry weight. Root release of14C was evident 2 DAT, and by 8 DAT 19.4% of the14C reaching the root system was released into the rooting medium. There was no metabolism of imazapyr in crown, root or adventitious shoot buds 2 DAT; however, imazapyr metabolism was evident in the treated leaf 2 and 8 DAT. Imazapyr phytotoxicity to leafy spurge appears to result from high imazapyr absorption, translocation to underground meristematic areas (roots and adventitious shoot buds), and a slow rate of m

ISSN:0031-613X    

DOI:10.1002/ps.2780450406

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAfter feeding 2,4‐D or atrazine in a diet to southern armyworm (Spodoptera eridaniaCram.) larvae for three days, the effect on total content and activities of cytochrome P450 and on insecticide toxicity were determined. Both 2,4‐D and atrazine induced cytochrome P450‐catalyzed aldrin epoxidation (AE) and methoxyresorufinO‐demethylatin (MROD). The 2,4‐D was a more potent inducer for total cytochrome P450 content, whereas atrazine disproportionately increased AE. Both compounds increased MROD significantly. The apparent kinetic characteristics of AE indicates that 2,4‐D and atrazine induced similar P450 isozymes (Km8.78 and 7.80 μM, respectively), which may differ from the constitutive isozyme (Km3.14 μM). The 2,4‐D‐induced cytochrome P450 contributed to decreased carbaryl and permethrin toxicity, whereas the atrazine‐induced cytochrome P450 caused decreased parathion and permethrin toxicity. The carbaryl toxicity correlated directly with 2,4‐D‐induced total P450 content and activities but not with atrazine‐induced changes. The 2,4‐D and atrazine also induced nonspecific esterase activity which may contribute t

ISSN:0031-613X    

DOI:10.1002/ps.2780450407

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe standard reference WHO/SRS house fly (Musca domesticaL.) strain was selected with beta‐cypermethrin (‚Chinmix’︁) by topical application for 25 consecutive generations. By the F25generation the LD50(expressed as ng per fly) increased to 164.9 × and 190.2 × initial values in the female and male flies, respectively, of the selected strain (CHXSEL).Developing rates and patterns of resistance seemed to be similar in both sexes and showed four characteristic phases: I. stagnant, II. quickly rising, III. slowly increasing and IV. plateau.Due to high mortality and low fertility of survivors after F25the selecting dosages could not be increased further, indicating that a selection limit had been reached.Upon termination of selection pressure the resistance reverted almost completely in the NOSEL substrain. The LD50decreased continuously and by the F60generation the resistance ratios (RR) were only 6‐9 and 10‐2 in the female and male flies, respectively.Synergist studies with different metabolic inhibitors, SKF‐525a, piperonyl butoxide, 1‐naphthylN‐propylcarbamate and NIA‐16388 suggested that both enhanced oxidase and esterase activity would contribute to the resistance of the CHXSEL strain. Moreover the analysis of the cross‐resistance pattern among pyrethroids makes the presence of a nerve insensitivity factor likely. The pattern of cross‐resistance within and outside the pyrethroid group is discussed in detail. The relationship of contributing resistance mechanism(s) to similarities of chemical str

ISSN:0031-613X    

DOI:10.1002/ps.2780450408

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe mosquito and blackfly pathogen,Bacillus thuringiensisBerl. var.israelensis(B.t.i.). containing spores and toxin crystal, was successfully encapsulated in an insolubilized carboxymethylcellulose (CMC)‐aluminum matrix creating a controlled‐release bead formulation. The release rate ofB.t.i.from this formulation was sufficient to killCulex sp.larvae during bioassays performed in the laboratory. The CMC concentration significantly affected the release rate of the bacterium. All types of beads tested exhibited a high initial release of B.t.i. in the first week of experiments, followed by a slower rate later. Levels of 10 g kg−1CMC solution and 0–05 m aluminium sulfate were found to be optimal in the formulation mixture for polysaccharide and gellant, respectively. This type of bead gave the fastest release of the bacterium and caused 100% larval mortality as from the second day of treatment. While acidic pH, high temperature and UV exposure drastically decreased spore viability ofB.t.i., the CMC‐encapsulated formulation was more stable to these conditions. Larvicidal activity of encapsulatedB.t.i.was more resistant to high temperature (50°C) than the unformulatedB.t.i.The high response ofCulexlarvae to the encapsulatedB.t.i.suggests that the formulation could be employed effectively in

ISSN:0031-613X    

DOI:10.1002/ps.2780450409

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThirty compounds comprising derivatives and analogues ofN‐(2‐cyano‐2‐methoximinoacetyl)methionine were synthesised and tested for anti‐fungal activity against grape downy mildew, caused byPlasmopara viticola(de Bary) Berl.&de Toni, and rape downy mildew,Peronospora parasiticaFr. The most fungicidal compounds were thetert‐butyl ester of the substituted methionine and its oxidation products, the sulfoxide and sulfone, and the methioninol derivative and its oxidation products. Some of these compounds were up to ten times more active, especially against the grape downy mildew, than the commercial fungicide cymoxanil. Thetert‐butyl esters of the methionine derivatives were consistently much more active than isomeric butyl esters, lower alkyl esters, free acids and S‐methylcysteine analogues of the active compounds, and possible reasons for these structure/activity correlation

ISSN:0031-613X    

DOI:10.1002/ps.2780450410

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA new route to the synthesis of 2‐(4‐ethoxyphenyl)‐2‐methyl‐5‐(3‐phe‐noxyphenyl)pentane (desfluoro MTI‐800) and 2‐(4‐ethoxyphenyl)‐2‐methyl‐5‐(4‐fluoro‐3‐phenoxyphenyl)pentane (MTI‐800) and the insecticidal activities of these compounds and some of the synthetic intermediates against the tobacco caterpi

ISSN:0031-613X    

DOI:10.1002/ps.2780450411

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY