摘要:

AbstractActivative thiolytic cleavage of the N‐S bond and self‐synergism in sulfenyl dicarbamate (SD) derivatives of 3,4‐methylenedioxyphenyl N‐methylcarbamate has been investigated. The formation of precursor carbamates by the reaction of the propoxur derivative with glutathione and cysteine was demonstrated by HPLC.The slower rate of insectidal action of SD‐propoxur compared with propoxur and its lower ki for inhibition of housefly acetylcholinesterase measured after preincubation of housefly head homogenate with N‐ethylmaleimide were considered as indirect evidence of the N‐S breakdown as a delay factor in toxicity.The SD‐carbaryl derivative, 3,4‐methylenedioxyphenyl N‐methylcarbamate, and piperonyl butoxide similarly inhibited the oxidative metabolism of [14C]carbaryl in post‐mitochondrial homogenates of housefly abdomens. The results indicated that activative thiolysis and self‐synergism performed by the methylenedioxyphenyl group could be processes involved in the insecticidal action of th

ISSN:0031-613X    

DOI:10.1002/ps.2780270302

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe influence of alkylphenol polyoxyethylene non‐ionic surfactants on the distribution pattern of MSMA (sodium hydrogen methylarsonate) was studied using scanning electron microscopy and X‐ray microanalysis elementmapping techniques. Surfactant concentrations and lipophilic–hydrophilic constitution influenced phytotoxicity and residue patterns. Surprisingly, the percentage of leaf surface covered bore little correlation to phytotox

ISSN:0031-613X    

DOI:10.1002/ps.2780270303

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractA single sub‐lethal dose of 0‐3 μg ivermectin applied topically to third (last) instar larvae of Calliphora vomitoria prevents a significant number of adult flies from escaping from their puparia after metamorphosis, although the flies show no signs of physical abnormality. Of the insects that manage to emerge, a significant number of females do not develop mature oocytes. Ivermectin in sub‐lethal doses seriously impairs post‐embryonic development in Calliphora at four independent levels: interference with pupariation, suppression of adult head development, inhibition of emergence from the puparium, and disruption of ovarian development in the adult female. These findings are discussed in relation to ivermectin's efficacy as a pesticide and particularly to non‐specific effects upon dung‐inhabi

ISSN:0031-613X    

DOI:10.1002/ps.2780270304

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractMany plant pathogens, viruses, fungi and bacteria, are spread by intermediaries or vectors. For some this is their only method of spread and for most viruses vectors are the normal agents of dispersal. Fungi, bacteria and some viruses are carried passively, as contaminants of the vector, whereas most viruses have a complex biological interaction with their vectors which is only now beginning to be understood.The control of pathogens carried passively can be achieved only by preventing contact between vector and pathogen. Therefore options for control include killing either vector or pathogen by a toxic pesticide or deterring the feeding of a potential vector. Viruses infecting plants cannot be killed by chemicals, therefore control has to be directed at the vector. The biological interactions between vector and virus offer opportunities for interfering with the transmission processes without recourse to toxic material.Interactions, especially between viruses and their vectors, are discussed in relation to current and future opportunities for control.

ISSN:0031-613X    

DOI:10.1002/ps.2780270305

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe probing and feeding behaviour of aphids can result in uptake of viruses from infected plants and subsequent transmission to healthy plants. It is possible to interfere with virus acquisition and transmission by influencing aphid host‐selection and feeding behaviour with antifeedant chemicals. Published work is reviewed and new work is presented in this paper. The two most successful classes of antifeedants against aphids are (a) compounds derived from the aphid alarm pheromone and (b) plant‐derived antifeedants such as the sesquiterpene (‐)‐polygodial. Results with these and other compounds are discussed in terms of antifeedant activity against Myzus persicae, their effects on resistant aphids and the evidence for decŕease in virus spread by aphids in laboratory a

ISSN:0031-613X    

DOI:10.1002/ps.2780270306

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractMosquitoes of the genus Culex, e.g. Culex quinquefasciatus, release a volatile pheromone from their eggs that induces gravid females to oviposit around the pheromone source. Enantioselective synthesis by the Sharpless epoxidation method and chiral gas chromatography showed the major pheromone component to be (−)‐(5R,6S)‐6‐acetoxy‐5‐hexadecanolide. Shortening the alkyl chain resulted in a loss of behavioural activity, whereas perfluorination of the alkyl chain or substitution of the acetoxy groups with the trifluoroacetoxy group gave active analogues. A simple large scale synthesis was devised to provide material for a fìeld trial. The pheromone, formulated in effervescent tablets, was used to concentrate oviposition in specific breeding sites where the larvae were controlled with a juvenoid‐ty

ISSN:0031-613X    

DOI:10.1002/ps.2780270307

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractInsecticide resistance is conferred by a limited number of clearly defined mechanisms. Previously, resistance detection in field populations of insects was confined to bioassays, which gave information limited to the presence of resistance to the insecticide tested. Biochemical tests have now been introduced into the field in Sri Lanka, which give information on the underlying mechanism of resistance. These tests, as well as being cheap and easy, work at the level of the individual insect and hence give information on the spectrum of resistance, the level of resistance and the frequency of resistance genes in field populations. In Sri Lanka, a malathion‐specific carboxylesterase has been detected in Anopheles culicifacies, an altered acetylcholinesterase in Anopheles nigerrimus and oxidase and glutathione S‐transferase based mechanisms in Anopheles subpictus. The selective advantage of resistant individuals under field insecticide spraying regimes has been estimated, and the relative importance of larval and adult insecticide selection asses

ISSN:0031-613X    

DOI:10.1002/ps.2780270308

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractRegression analysis is the most commonly used technique in QSAR studies. Whilst regression has its advantages, it also suffers from a number of disadvantages. A variety of mathematical and statistical techniques exist which complement or replace regression. These may he classified as ‘supervised’ and ‘unsupervised’ learning methods where supervision refers to the use made of biological data in the analysis. These terms are discussed and examples of three unsupervised and two supervised learning methods are presented. The techniques described are Non‐Linear Mapping, Principal Components Analysis, Cluster Analysis, Canonical Correlation Analysis and Factor Analysis. Although the examples presented are mostly pharmaceutical applications, it is proposed that the extra complexity of pesticide research data, compared with pharmaceutical, makes it very well suited to analysis by thes

ISSN:0031-613X    

DOI:10.1002/ps.2780270309

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe structure/activity relationships of substituted benzyl (1RS)‐transcyclopropane‐1‐carboxylate insectieides have been investigated by a combination of multivariate statistical techniques and molecular modelling. Quantum and molecular mechanics were used to calculate a set of seventy descriptors to represent the molecular properties of the series. These can be summarised by eight uncorrelated factors which describe the associations between the seventy descriptors with little loss of information. The neurotoxicities, knockdown and killing activities of the compounds are associated with the same three physicochemical factors, suggesting that common molecular features are required for these different responses. In this series, high biological potency is conferred by the presence of a partial positive charge at a meta carbon in the benzyl ring of the alcohol moiety, small nucleophilic superdelocalisabilities on the carbonyl carbon and oxygen atoms of the ester linkage, and chlorosubstituents subtended by the terminal carbon atom of the vinyl side chain at C3 of the cyclopropane ring. An additional property related to the nucleophilic superdelocalisabilities of the ortho and meta carbons of the benzyl ring is required for knockdown act

ISSN:0031-613X    

DOI:10.1002/ps.2780270310

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractIt is believed that the different classes of compound which interfere with photosynthesis system II (PS 11) must act by binding at different sites, because they appear to be structurally so dissimilar. However, it can be argued that some of the classes of compound of diverse structural type share very similar external surface features. Now that details about the binding oj PSII inhibitors are becoming available, it will be possible to see how many of the different compound classes actually bind similarly. In future, increasingly detailed knowledge of the structures of potential sites of action will be available. QSAR methods will need to be used together with molecular modelling to be effective tools for agrochemical design.

ISSN:0031-613X    

DOI:10.1002/ps.2780270311

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY