摘要:

AbstractThe methods used to evaluate and categorise the effects of pesticides on beneficial arthropods are reviewed, including the potential significance of indirect, ‘sub‐lethal’ activity and the importance of bioavailability of pesticides under semi‐field or field conditions. Interspecific and intraspecific differences in the susceptibility of natural enemies (parasitoids and predators) to pesticides are considered, including the use of resistant strains in Integrated Pest Management (IPM) systems. The potential impact of pesticide resistance in the target pest on its natural enemies is also discussed. The need to assess the influence of the host plant/cultivar on the efficacy of pesticides for use in integrated control programmes (ditrophic effects) and of the possible effects of such chemicals on host plant/cultivar‐pest‐parasitoid systems (tritrophic effects) are then described with specific reference to the diamondback moth and key endolarval parasitoids. Finally, the potential for manipulation of tritrophic interactions to enhance parasitism by application of low doses of toxicants is d

ISSN:0031-613X    

DOI:10.1002/ps.2780440302

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractMore than 20N‐(2‐cyano‐2‐methoximinoacetyl)amino acids and derivatives were synthesised and tested for antifungal activity against grape downy mildew, caused byPlasmopara viticola(de Bary) Berl.&de Toni, and rape downy mildew,Peronospora parasiticaFr. Two of the compounds containing a free carboxylic acid group, a moiety which has been shown to confer phloem mobility on compounds, showed high activity, especially againstP. parasitica, in protectant tests. These results indicate that there is no incompatibility between the acid function and fungicidal activity. A number of the esters showed activity comparable with that of cymoxanil in the protectant tests, and thetert‐butyl esters of the methionine derivative and its sulfone were more than ten times as active as the commercial

ISSN:0031-613X    

DOI:10.1002/ps.2780440303

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractBased on our previous finding that PIM (phenyl‐imidazolyl‐metyra‐pon; 2‐(1‐imidazolyl)‐2‐methyl‐1‐phenylpropan‐1‐one, 1) is a strong inhibitor of ecdysone 20‐monooxygenase (IC50= 7.89 × 10−7M) from the fleshfly,Neobellieria bullata(Parker) and has also a good toxic actionin vivoagainst this insect, 17 imidazole and 1,2,4‐triazole analogues of metyrapone were synthesized and evaluated for their action againstN. bullatalarvae in terms of toxicity, length of larval development, weight of the puparium as well as special symptoms, i.e. malformations of the anterior and posterior spiracles, and of the mandibles. The introduction ofp‐methoxy (LC50= 49 mg kg−1in diet) orp‐chloro (LC50= 97 mg kg−1) substituents on the benzene ring of PIM resulted in a significant increase in toxicity compared to that of metyrapone (LC50= 561 mg kg−1) and PIM (LC50= 148 mg kg−1). The hybridization state of the carbon atom adjacent to the benzene ring was not an important factor for toxicity because the acetoxy derivative (13) was almost as toxic as PIM. At least one methyl group was required on the carbon atom adjacent to the azole ring to maintain activity, while an ethyl group (4) enhanced the toxic effect. At the applied doses some compounds including metyrapone itself, extended the duration of the larval development. Only metyrapone and PIM decreased the puparium weight. Several derivatives induced lethal malformations of mandibles as well

ISSN:0031-613X    

DOI:10.1002/ps.2780440304

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIn a study of the fresh‐water teleostClarias batrachusL., fish were exposed to a commercial 300 g litre−1EC formulation (of dimethoate at 10.8 mg AI litre−1) for a period of six months extending over prespawning, spawning and postspawning phases of the annual reproductive cycle. A parallel group of fish without dimethoate served as control. Significant reduction in the fecundity pattern of exposed fish was noticed throughout the experimental period. The gonadosomatic indices of both male and female exposed fish were reduced when compared with the control fish. The reduction continued until the termination of the experiment. It was inferred from the present study that, at this level, this pesticide affects the reproductive potential of this

ISSN:0031-613X    

DOI:10.1002/ps.2780440305

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractSpontaneous neuronal activity was recorded from the peripheral nerves of third‐instar larvae of strains ofHeliothis virescens(F.) obtained directly from cotton fields in the USA. Following a control period the preparations were exposed to increasing concentrations ofcis‐cypermethrin in a cumulative dose‐response assay. A positive response was defined as an increase of at least five‐fold in the rate of neuronal activity over that seen during the control period. Up to 35 individuals of each strain were assayed and the responses used to construct a phenotypic profile categorising the individuals from nerve‐susceptible to highly nerve‐insensitive. An EC50for the action ofcis‐cypermethrin was also obtained. There was a positive, significant correlation between non‐synergisable resistance to cypermethrin and nerve insensitivity as defined in the neurophysiological assay. It was shown that nerve insensitivity to cypermethrin increased throughout the cotton

ISSN:0031-613X    

DOI:10.1002/ps.2780440306

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA series of isothiocyanates (R‐NCS, R, 1–6 carbon atoms) was applied in the vapour phase to wheat in sealed containers. The speed of sorption, as measured by the rate of loss from the intergranular air space, was inversely proportional to molecular weight; e.g. the time for 50% sorption of hexyl isothiocyanate was over 100 times longer than for the methyl analogue. Despite extensive sorption, most of the applied chemicals was recovered from the fumigated wheat seven days after dosing, indicating that sorption did not lead to extensive degradation. Purge and trap techniques proved suitable for recovery of low‐boiling, but not high‐boiling ch

ISSN:0031-613X    

DOI:10.1002/ps.2780440307

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe antibiotic nucleoside tubercidin produced byStreptomyces viola‐ceonigerwas evaluated for in‐vivo efficacy and in‐vitro activity against Phytophthora capsici, Magnaporthe grisea andColletotrichum gloeosporioides. Tubercidin was more effective againstP. capsiciandM. griseathan againstC. gloeosporioidesin inhibiting mycelial growth. The bioassay on TLC plates was the most sensitive method and allowed the evaluation of antifungal activity of tubercidin even at a low concentration of 0.1 μgml−1. As compared to the systemic fungicide metalaxyl, tubercidin was similar or somewhat higher in inhibition of mycelial growth ofP. capsici. When applied to pepper stems, tubercidin was equally as effective as metalaxyl in the control of phytophthora blight in pepper plants, irrespective of application time and concentration. The treatment with 1000 μg ml−1tubercidin induced phytotoxicity in pepper plants. No control efficacy of phytophtora blight was observed in pepper plants supplied with a soil drench of tubercidin. Treatment with tubercidin at 500 μg ml−1completely protected pepper plants at first branch stage from phytophthora blight until four days after application. The control efficacy of tubercidin drastically declined seven days aft

ISSN:0031-613X    

DOI:10.1002/ps.2780440308

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractOptimisation of activity in 3‐[(alkoxyimino)methylbenzyl] esters has been investigated by introducing an α‐cyano group and a fluorine atom in position 4 of the benzylic moiety in conjunction with varying the length and nature of the side chain. Of the five side‐chain variations investigated, the 3‐methoxyiminomethyl was more effective than others. Introduction of fluorine in position 4 of the benzylic moiety generally increased activity, particularly against mustard beetles, as in previous instances. Surprisingly, the effect on insecticidal activity of introducing an α‐CN group ranged from positive to negative depending upon the nature of the alkoxyimino substituent, an effect not observed previously. The most effective esters were derived from α‐cyano‐4‐fluoro‐3‐[(methoxyimino)methyl]benzyl alcohol, which was synthesised from 2‐{4‐fluoro‐3‐[(hydroxyimin

ISSN:0031-613X    

DOI:10.1002/ps.2780440309

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractActivities of a range of pyrethroidal esters, incorporating structural variations in all regions of the acid and alcohol components, have been measured against two fully characterised and homozygous resistant strains ofMusca domesticaL. (kdrandsuper‐kdr). The results, limited in this paper to esters of alcohols withcyclicside chains, indicate uniform resistance to thekdrstrain across the whole range of structural variations. Against thesuper‐kdrstrain, while variation in the acid component has little effect, the resistance factor is sensitive to the nature of the alcohol component, in particular on whether it contains an α‐cyano subst

ISSN:0031-613X    

DOI:10.1002/ps.2780440310

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractActivities of a range of pyrethroidal esters, incorporating structural variations in all regions of the acid and alcohol components, have been measured against two fully characterised and homozygous resistant strains ofMusca domestica (kdrandsuper‐kdr). The results, limited in this paper to esters of alcohols withacyclicside chains, show the same level of uniform resistance as thekdrstrain observed previously, across a range of acid and alcohol variations. Against thesuper‐kdrstrain, in contrast to thecyclicside chain set, resistance factors are barely higher than for thekdrstrain. Againstsuper‐kdrflies, some dependence of resistance factor on the position of the side chain substituent was detected. Polyfluorobenzyl esters confer particularly low resistance fa

ISSN:0031-613X    

DOI:10.1002/ps.2780440311

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY