摘要:

AbstractTwenty‐one synthetic compounds, containing one or more furan rings, were demonstrated to possess anti‐juvenile hormone (AJH) activity as evidenced by their induction of premature metamorphosis in the milkweed bug,Oncopeltus fasciatus(Dallas) by contact, topical application or fumigation. The ED50of the four most active analogs required to induce precocious metamorphosis from 3rd‐instar nymphs by residue contact in a Petri dish compared favorably with that of precocene II (6,7‐dimethoxy‐2,2‐dimethyl 2H‐chromene) a naturally occurring phytochemical AJH. Precocious metamorphosis was fully reversible by co‐treatment with juvenile hormone (JH III) or JH analogs, demonstrating that the observed AJH activity resulted from an induced deficiency of j

ISSN:0031-613X    

DOI:10.1002/ps.2780430102

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractSeventeen substituted imidazoles were tested as inhibitors of juvenile hormone (JH) III synthesis by cockroach corpora allata in an in‐vitro radio‐chemical assay. Most of these 1,5‐disubstituted imidazoles were highly potent, with IC50values of less than 100nM. The compounds differed in their ability to cause an accumulation of the precursor methyl farnesoate in the glands. Four of the imidazoles were tested by topical application to previtellogenic adult females, and all caused a significant inhibition of JH synthesis and an accumulation of intraglandular methyl farnesoate for at least three days after treatment. Methyl farnesoate epoxidase activity of homogenates of corpora allata was inhibited by the compoundsTH‐14 andTH‐27. This P450‐dependent epoxidase activity was inhibited at less than 10 nM. The results show that the 1,5‐disubstituted imidazoles are powerful inhibitors of the last step of juvenile synthesis in t

ISSN:0031-613X    

DOI:10.1002/ps.2780430103

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe susceptibility of three clones ofAphis gossypiiGlover to 15 insecticides was established by bioassay. A high level of resistance towards pirimicarb was confirmed for a clone from Holland (Dutch R) and a clone from Japan (Jap R), while the susceptible clone (S) was killed by very low doses of the insecticide. However, only limited cross‐resistance was shown towards other carbamates and organophosphates, and no marked resistance to the pyrethroids tested. The acetylcholinesterase (AChE) of both resistant clones hydrolysed acetyl‐choline faster than that of susceptible aphids, with greatest enzyme activity shown by the Dutch R clone. Inter‐clone differences in these rates were consistent with differences in catalytic centre activities. Inhibition (I50) of AChE by pirimicarb was approximately 900‐fold higher for the resistant clones than for the S clone. First‐order kinetics revealed that resistance to pirimicarb in Dutch R and Jap R involved a modified AChE which had a reduced (approximately 350‐fold) affinity (Kd) for pirimicarb. The marked change in AChE affinity for pirimicarb was not repeated with the other carbamates tested, ethiofencarb and aldicarb. It was considered that the resistant aphids would not require mechanisms in addition to insensitive AChE in order to show the high level of resistance to pirimicarb shown in t

ISSN:0031-613X    

DOI:10.1002/ps.2780430104

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractProteins extracted from suspension‐cultured soybean (Glycine max(L.) Merr. Corsoy 79) cells containedO‐ andN‐glucosyltransferases (GTs; EC 2.4.1) that catalyzed glucosylation of several xenobiotic compounds including (a) the hydroxylated herbicide metabolites 6‐hydroxybentazone (B‐6‐OH), 8‐hydroxybentazone and 5‐hydroxydiclofop (b) the herbicide chloramben and (c) the environmental contaminants 2,4‐dichlorophenol and 3,4‐dichloroaniline. The O‐GT that catalyzes B‐6‐OH glucosylation, UDP‐glucose: B‐6‐OH glucosyltransferase (B6GT), was chosen for further study. A rapid and sensitive B6GT assay was developed that uses ethyl acetate extraction to separate the product 6‐O‐[14C]glucosylbentazone from the glucose donor uridine[5′]diphospho‐[1]‐α‐D‐[U‐14C]glucose. B6GT, recovered in the soluble protein fraction, was extracted in consistently high amounts from Corsoy 79 cells cultured for one to seven days. 2‐Mercaptoethanol in the extraction buffer increased B6GT activity as did sodium, potassium, calcium, magnesium or manganese(II) chlorides in the assay buffer. B6GT activity in an ammonium sulfate fraction (30–50% saturation pellet) displayed two pH optima, one at pH 5.5 and another at pH 10 to 11. Apparent Kmvalues for UDP‐glucose and B‐6‐OH in the ammonium sulfate fraction were 90 and 4.5μM, respectively. Thus, we have partially characterized glucosylation of B‐6‐OH, one example of th

ISSN:0031-613X    

DOI:10.1002/ps.2780430105

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe systemic morpholine fungicide tridemorph, which is known to exert its antifungal action through inhibition of ergosterol biosynthesis, can also inhibit the growth of organisms which are incapable of sterol biosynthesis. It was found to inhibit strongly glucose and lactate dehydrogenase activities in cultures of four Gram( +) bacteria, Rhodococcus sp. AK 1, Bacillus cereus Frankland&Frankland,Bacillus subtilis(Ehrenberg) Cohn,Nocardia asteroidesand a Gram(−) bacterium,Rhizobium leguminosarum.Growth of these bacteria was inhibited by tridemorph at concentrations between 7 and 60 mg litre−1. In contrast, similar dehydrogenase activities in other Gram(−) organisms,Escherichia coliCast.&Chalm. andAzotobacter vinelandii, which showed no growth inhibition at 200 mg litre−1tridemorph, were either not inhibited or inhibited only slightly. Similarly, succinate dehydrogenase activity inRhodococcussp. AK 1 was more strongly inhibited by tridemorph than that in E.coli.In cell‐free extracts ofRhodococcussp. AK1 and E.coli, lactate dehydrogenase activity was also inhibited by tridemorph to a much greater extent in the sensitive strain (63%) than in the resistant

ISSN:0031-613X    

DOI:10.1002/ps.2780430106

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIn 1993 we observed the sensitivity of wheat powdery mildew populations (Erysiphe graminisDC f.sp.triticiMarchal) from the Czech Republic, Austria, Hungary and Slovakia to the fungicides triadimenol, tebuconazole, propiconazole, flutriafol and fenpropimorph. The highest resistance value was shown to triadimenol, which attained a mean resistance factor (MRF) of 29 (expressing how many times the population is more resistant than are standard sensitive isolates) in the mildew population from the Czech Republic. The mildew populations from eastern Slovakia and eastern Hungary, populations geographically isolated from the other populations, showed very high sensitivity to all fungicides tested. There was most sensitivity to fenpropimorph (smallest MRF values) compared with the other fungicides. Cross‐resistance was established among all triazoles used, but not between triazoles and fenpropimorph. Sensitivity of wheat powdery mildew populations from Central Europe to these fungicides is considered adequate, and the development of resistance has shown a decreasing tendency in recent year

ISSN:0031-613X    

DOI:10.1002/ps.2780430107

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe persistence of tralkoxydim herbicide in wheat crop and in soil was evaluated under Indian sub‐tropical field conditions at two application rates (400 g a.i ha−1and 800 g a.i ha−1). At 400 g a.i ha−1, tralkoxydim persisted up to 28 days in soil but became non‐detectable only after 45 days in the crop. However, at 800 g a.i ha−1, tralkoxydim residues persisted for 45 days in both soil and crop. The dissipation of the herbicide from both soil and crop appeared to occur in two phases at both rates of application. Each phase followed first‐order kinetics. The values of DT50and DT90for both soil and crop

ISSN:0031-613X    

DOI:10.1002/ps.2780430108

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe biochemical mechanisms of warfarin resistance in the house mouse (Mus musculusL.) have not been fully investigated. In some populations of warfarin‐resistant mice there is a reduction in sensitivity of hepatic vitamin K‐epoxide reductase to inhibition by warfarin. This is similar to a proposed mechanism of anticoagulant resistance in the Norway rat (Rattus norvegicusBerk.). The same enzyme in other warfarin‐resistant populations is, however, sensitive to warfarin inhibition. Other studies have indicated that detoxification may play a role in conferring warfarin resistance in house

ISSN:0031-613X    

DOI:10.1002/ps.2780430109

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractWidespread anticoagulant resistance was discovered in populations of the brown rat (Rattus norvegicusBerk.) in an area of roughly 8000 km2in north‐west Germany. Resistance testing was performed by feeding tests and/or by measuring blood clotting response after intraperitoneal injection of a sublethal testing solution. A hierarchical resistance system was found with warfarin resistance at the base followed by bromadiolone/coumatetralyl resistance to difenacoum resistance at the top. Warfarin resistance was spread over the whole area with reduced incidence towards the edges. Difenacoum resistance represented the highest level found so far and was restricted to the inner zone of the resistance area where it occurred with a frequency of 6% of all individuals tested.Breeding experiments with bromadiolone‐resistant rats showed that expression of the bromadiolone resistance gene differed in the two sexes, suggesting additional sex‐linked modifying effects to the resistance gene. Control strategy within the resistance area with respect to prevention of further selection for resistance is disc

ISSN:0031-613X    

DOI:10.1002/ps.2780430110

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractResistance to the first successful anticoagulant rodenticide, warfarin, was detected in the Norway rat (Rattus norvegicusBerk.) in 1958, and it has since expanded to cover other commensal rodent species (R. rattusL.,Mus musculusL.) and the majority of later‐developed anticoagulant compounds. The purpose of this paper is to give an up‐to‐date picture of the current distribution of anticoagulant resistance in Europe, as revealed by the questionnaire dispatched by EPPO (European and Mediterranean Plant Protection Organization) to its member countries in 1992. Replies were received from 13 countries (43% of EPPO members), and it was found that broad‐spectrum resistance occurred in practically all those countries that reported testing activity. A likely conclusion based on this finding is that true distribution of resistance is certainly more extensive than documented by the questionnaire replies. Another conclusion drawn by the EPPO Rodent Control Panel was that the existing resistance detection protocols were no longer adequate to cover the whole array of existing anticoagulant rodenticides. Consequently, a new guideline including novel methods particularly for detecting resistance to single‐dose anticoagulant compounds was urgently needed. This guideline is currently und

ISSN:0031-613X    

DOI:10.1002/ps.2780430111

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY