bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bemisia tabaci in the Netherlands; here to stay?
Authors: Fransen Joanne J. 
Published: November 2006

AbstractIn autumn 1987, the first observations were made in the Netherlands of a whitefly species identified as type ‘B’ of the sweet potato whitefly, Bemisia tabaci (Gennadius), on the host plant poinsettia, Euphorbia pulcherrima Willd. ex Klotzsch. Although an eradication programme was initiated, total eradication was not obtained. Over the years B. tabaci has persisted on poinsettia and slowly spread to other crops like Begonia, Bouvardia, Gerbera and Hibiscus. Vegetables like tomato, cucumber and egg plant have also become infested.B. tabaci often develops extensively during the summer season due to its better adaptation to temperatures of ⩾25°C compared with the greenhouse whitefly, which develops more readily at 20°C. During the poinsettia growing season, high population numbers of B. tabaci will not develop, but any plants showing visible signs of infestation, such as an empty pupal case, are rejected at the auction. The integration of biological and chemical control is expected to show better potential than the use of insecticides, as insecticide resistance has already been observed. Several natural enemies, such as certain strains of the parasitoids Encarsia formosa Gahan and Eretmocerus californicus Howard, as well as the predators Delphastus pusillus Leconte and Macrolophus caliginosus Wagner, are being tested in green‐houses. Research is also carried out regarding the use of insectpathogenic fungi such as Aschersonia spp., Verticillium lecanii (Zimm.) Viegas and Paecilomyces spp.
A bioassay for determining simazine in water using aquatic flowering plants (Ceratophyllum oryzetorum, Ranunculus trichophyllus and Alisma plantago‐aquatica)
Authors: Ou Ziqing , Sun Tieheng , Zhang Hairong 
Published: November 2006

AbstractA simple and rapid bioassay for the measurement of simazine in water using aquatic flowering plants (Ceratophyllum oryzetorum Kom., Ranunculus trichophyllus Chaix. and Alisma plantago‐aquatica L.) is reported in this paper. It is based on the effect of simazine on the amount of oxygen produced by photosynthesis which is measured directly using a Clark‐type oxygen electrode. This method is rapid, sensitive, and capable of measuring a simazine concentration of 0.02 mg litre−1 within 10 min of treatment. The precision of this method was examined with spiked river water by comparing the results obtained with HPLC. Mean recoveries of simazine measured by bioassay using C. oryzetorum were 96 to 100% which were comparable to those (98 to 100%) obtained with C18 column extraction and HPLC measurement. The results obtained by the two methods showed excellent agreement. Maintenance of stock cultures of the plants and the bioassay procedure itself were much simpler and more easily conducted than methods using algae.
Modelling penetration of plant cuticles by crop protection agents and effects of adjuvants on their rates of penetration
Authors: Schönherr Jörg , Baur Peter 
Published: November 2006

AbstractA theory of cuticular penetration of crop protection agents (CPAs) is presented, which incorporates properties of cuticles and cuticular waxes as well as properties of active ingredients and adjuvants. Based on this theory, two models are developed which are analytical in the sense that they help to quantify and understand (i) differences in permeability among cuticles from different species, (ii) effects of properties of CPAs on permeabilities of cuticles and rates of uptake and (iii) the effects of adjuvants on properties of cuticles and rates of uptake of CPAs. The models can be used to predict rates of uptake of CPAs as affected by properties of cuticular waxes, active ingredients and adjuvants. However, before this can be done, a constant, two parameters and at least two variables must be estimated. Properties of cuticles are accounted for by the constant D0/Δx and the parameter β′. The former, the ratio of the mobility of a hypothetical molecule having zero molar volume (D0x) divided by the path length (Δx) across the cuticle, has the dimension of velocity (ms−1) and is independent of the solubility of the CPA. The latter is a measure of size selectivity of the cuticle. Differences in permeabilities of cuticles from different species increase with increasing size of active ingredients due to size selectivity (β′). Removing cuticular waxes from Citrus cuticles increased D0/Δx by a factor of 2042, while β was not affected. Differential solubility of CPAs is considered part of the driving force and at least two different partition coefficients are needed to account for differences in solubilities in cuticular waxes, cutin, water and the formulation residue on the surface of the cuticles. Adjuvants are solvents in the formulation residue on the leaf surface once the carriers (water and other volatile solvents) have evaporated and certain adjuvants also act as accelerators; they penetrate the cuticle and increase D0/Δx. Thus, accelerators increase rates of uptake and this effect depends on two factors, (i) the intrinsic activity of the accelerator and (ii) rate of penetration into the cuticle, because the active ingredients follow the accelerator front across the cuticle. Since accelerators penetrate from the formulation residue into the cuticle, the volume of the formulation residue decreases with time. This maintains high concentrations of CPAs in the formulation residue and, thus, maximum driving forces and rates of penetration. To utilise fully this dual accelerator effect, it is necessary to match velocities of penetration of accelerators and active ingredients accurately.
Principles in the absorption, distribution and elimination of pharmaceuticals
Authors: Gumbleton Mark , Forbes Benjamin J. 
Published: November 2006

AbstractThe processes by which the body handles drugs and which determine the temporal profile of drug concentrations in the body can be conveniently categorized into: absorption—process of drug transport from the site of release of drug from the delivery system into the systemic blood circulation; distribution—process of reversible transport of drug molecules from the site of absorption to those tissues of the body into which the drug is able to distribute; and elimination—process of irreversible removal of drug molecules from the body. Elimination of drug from the body will occur by metabolism—chemical modification of drug, and/or excretion—physical removal of drug from the body, e.g. renal or biliary excretion. This article first discusses the composition and structure of mammalian cell membranes, as this is fundamental to understanding the relationship between a drug's physicochemical properties and its membrane transport, and as a corollary, the understanding of the processes of drug absorption, distribution and elimination. Mechanisms involved in the absorption, distribution and elimination of pharmaceuticals are then discussed through integration of mammalian physiology, biochemistry and drug physicochemical properties. Further, the effect of changes in the above processes upon drug concentration‐time profiles in the body is considered.
Examination of stability of resistance and cross‐resistance patterns to acylurea insect growth regulators in field populations of the diamondback moth,Plutella xylostella, from Malaysia
Authors: Furlong Michael J. , Wright Denis J. 
Published: November 2006

AbstractIn teflubenzuron and teflubenzuron/chlorfluazuron laboratory‐selected sub‐populations of a Cameron Highlands (1988) strain ofPlutella xylostellaL., resistance to teflubenzuron reached much greater levels than chlorfluazuron but declined at a correspondingly greater rate to give similar resistance levels after 10–13 generations. There was little evidence of cross‐resistance to flufenoxuron and none to hexaflumuron in these populations. Reselection of a Cameron Highlands population with teflubenzuron after 22 generations resulted in a significant (P< 0.05) increase in resistance after three generations. In two more recently collected strains from lowland Malaysia, Sawi (1991) and Serdang (1992) high levels of resistance to teflubenzuron were found, but only the former showed any apparent resistance to chlorfluazuron. There was also evidence of resistance to diflubenzuron in the Sawi strain (Serdang not examined). Resistance to teflubenzuron appeared to be unstable in unselected sub‐populations of both lowland strains. Selection of the Sawi strain with teflubenzuron did not effect cross‐resistance to chlorfluazuron, while attempted selection with chlorfluazuron had no effect on resistance to either compound. Selection of the Sawi strain with diflubenzuron increased resistance to teflubenzuron but had no effect on resistance to chlorfluazuron. In contrast to the Sawi strain, selection of the Serdang strain with teflubenzuron resulted in cross‐resistance to chlorfluazuron. Synergist experiments with piperonyl butoxide (PB) andS,S,S‐tributyl phosphorotrithioate (DEF) suggested that resistance to teflubenzuron in the lowland strains may involve both microsomal monooxygenases and esterases. The ovicidal activity of teflubenzuron, chlorfluazuron, hexaflumuron and flufenoxuron was consistently less than their activity against second‐instar larvae, hexaflumuron, followed by teflubenzuron, showing the greatest relative ovicidal activity. Hexaflumuron was markedly more active than teflubenzuron against eggs from acylurea‐selected Cameron Highlands populations and there was some evidence that resistance to teflubenzuron may be expressed at a lower level in eggs than in larvae in one such strain.
A biochemical mechanism of resistance to pirimicarb in two glasshouse clones of Aphis gossypii
Authors: Silver Andrew R. J. , Van Emden Helmut F. , Battersby Martin 
Published: November 2006

AbstractThe susceptibility of three clones of Aphis gossypii Glover 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 the bioassay.
Fungicide sensitivity of populations of wheat powdery mildew (Erysiphe graminis f.sp. Tritici) in Central Europe in 1993
Authors: Švec Miroslav , Miklovičová Marta , Sýkora Milan , Krippel Eduard 
Published: November 2006

AbstractIn 1993 we observed the sensitivity of wheat powdery mildew populations (Erysiphe graminis DC f.sp. tritici Marchal) 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 years.
Resistance to anticoagulant rodenticides in Germany and future strategies to control Rattus norvegicus
Authors: Pelz Hans‐Joachim , Hänisch Detlef , Lauenstein Gerhard 
Published: November 2006

AbstractWidespread anticoagulant resistance was discovered in populations of the brown rat (Rattus norvegicus Berk.) in an area of roughly 8000 km2 in 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 discussed.
Influence of different field sites on pesticide movement into subsurface drains
Authors: Traub‐Eberhard Ute , Henschel Klaus‐Peter , Kördel Werner , Klein Werner 
Published: November 2006

AbstractPesticide movement to subsurface drains was monitored in two typical crop production areas in Germany. Field trials were conducted on two subsurfacedrained soils, a silt loam and a poorly structured sandy soil, under different climatic conditions. Over a period of one year, the drainflow was measured and the drain water was analysed for all applied herbicides.Different leaching behaviour was observed at the two field sites. Following autumn application of pendimethalin and isoproturon to the Soester Börde soil, maximum concentrations of about 62 μg litre−1 for isoproturon and 0.7 μg litre−1 for pendimethalin were observed in drainflow from this silt loam. The early occurrence of both herbicides in the drain water only two days after application is consistent with fast flow through macropores. In contrast, on the subsurfacedrained sandy soil in Brandenburg, isoproturon did not reach the drains until two months after autumn application and was found at maximum concentrations of only 1.4 μg litre−1; pendimethalin was not detected in the drain water.Pesticide movement after spring application seemed to be of minor importance. At both locations, spring application led to low concentrations of pesticides in the drainflow (pendimethalin < 0.01 μ litre−1; metolachlor ⩽ 0.05 μ litre−1; chloridazon ⩽ 0.15 μ litre−1; metamitron ⩽ 0.02 μg litre−1; terbuthylazine ⩽ 1.4 μ litre−1).
Using allele‐specific oligonucleotide probes to characterize benzimidazole resistance in Rhynchosporium secalis
Authors: Wheeler Ian E. , Kendall Sheila J. , Butters Jenny , Hollomon Derek W. , Hall Len 
Published: November 2006

AbstractBenzimidazole fungicides are important mixture components in strategies to combat fungicide resistance in Rhynchosporium secalis Davis. To monitor the performance of these strategies, a rapid, accurate assay has been developed to detect point mutations in the β‐tubulin gene which confers resistance of benzimidazoles. The β‐tubulin gene of a benzimidazole‐resistant strain of R. secalis has been cloned and sequenced. Except for the difference in the position of one of its six introns, this gene showed a strong homology with other β‐tubulin genes from filamentous fungi. Resistance was related to a point mutation in codon 198 which caused a glutamic acid to glycine change in resistant field strains, but glutamic acid to lysine in a laboratory mutant. A DNA fragment surrounding codon 198 was amplified directly from diseased lesions using a ‘nested’ set of PCR primers. Combining PCR amplificiation of a target DNA sequence with hybridization of Allele‐Specific Oligonucleotide probes (ASOs, 15‐mers) allowed accurate detection of benzimidazole resistance. Only two probes, one sensitive and one resistant, were sufficient to monitor current field populations. Detection was achieved using either 32P‐labelled probe, or non‐radioactively using a biotin‐labelled probe coupled to streptavidin/alkaline phosphatase. This rapid method using ASOS can detect benzimidazole resistance within 48 h compared with 6–8 weeks by conventional assay procedures.
Changes in free amino acid pools can predict the mode of action of herbicides
Authors: Singh Bijay K. , Shaner Dale L. 
Published: November 2006

AbstractStudies were conducted to determine the short‐term changes in free amino acid levels in the meristematic zone of maize after treatment with various herbicides with different modes of action. These herbicides included inhibitors of various amino acid biosynthetic pathways, photosynthesis, and fatty acids biosynthesis. Inhibitors of various amino acid biosynthetic pathways caused specific reduction in the pools of amino acids being produced by the particular pathway. Inhibitors of other metabolic pathways also caused significant changes in pools of various amino acids. Very similar changes in the pools of amino acids were seen in plants treated with different chemical classes of inhibitors affecting a certain metabolic pathway. However, the changes were quite different between inhibitors of different metabolic processes. The data generated from these studies could be used as a diagnostic tool to determine the mode of action of novel herbicides.
Cytochrome P450 in the house fly: Structure, catalytic activity and regulation of expression of CYP6 A1 in an insecticide‐resistant strain
Authors: Feyereisen René , Andersen John F. , Cariño Flerida A. , Cohen Michael B. , Koener Josette F. 
Published: November 2006

AbstractThe house fly P450 CYP6Al was cloned and sequenced. This gene was mapped to chromosome V of the house fly. Upstream of the transcription start site are sequences (barbie boxes) that may be related to the inducibility of the gene by phenobarbital. The coding sequence of CYP6Al is interrupted at the Glu364 codon by a single intron of 60 bp, as in five related CYP6 genes that are present on the same chromosome. The catalytic activity of CYP6Al was analyzed in a reconstituted system of house fly P450 reductase and CYP6Al. The cDNAs for these two components of the microsomal P450 system were expressed in Escherichia coli. CYP6Al epoxidized the cyclodiene insecticides heptachlor and aldrin at a high rate. The CYP6Al gene was shown to be constitutively overexpressed in several insecticide‐resistant strains, including the multi‐resistant Rutgers strain. This high constitutive expression is not caused by an amplification of the CYP6Al gene. Overexpression of the CYP6Al gene is controlled by an incompletely dominant locus on chromosome II, both in larvae and in adults. This shows that overexpression is the result of a mutation affecting a trans‐acting factor that regulates CYP6Al expression on chromosome V. Metabolic resistance to insecticides (organophosphorus compounds, carbamates, juvenile hormone analogs etc.) has been mapped repeatedly to chromosome II in the house fly by genetic methods, and these results support the hypothesis of Plapp that a major resistance gene on chromosome II is a regulatory gene.
Photodegradation of the carbamate insecticide ethiofencarb
Authors: Kopf Gudrun , Schwack Wolfgang 
Published: November 2006

AbstractIn order to study the photoreactivity and possible photodegradation pathways of ethiofencarb (2‐ethylthiomethylphenyl methylcarbamate) on plant surfaces, model experiments in the presence of cyclohexane, cyclohexene methylcarbamate)onand iso‐propanol were performed. Both artificial light (λ > 280 nm) and natural sunlight were used. Half‐lives of the ethiofencarb photodegradation were in the order cyclohexane < isopropanol < cyclohexene and ranged from 75 min to more than 20 h. Depending on the solvent and the light source chosen, different photo‐products were obtained. When ethiofencarb was irradiated in the presence of cyclohexane, photo‐oxidation to the corresponding sulfoxide was the main degradation pathway, followed by a cyclization reaction. In the case of isopropanol as model solvent, numerous photoproducts were detected as a result of photo‐oxidation, hydrolysis and the addition to ethiofencarb of the solvent molecule.
Quantitative structure—activity studies of some octopaminergic agonists against Periplaneta americana
Authors: Hirashima Akinori , Taniguchi Eiji , Eto Morifusa 
Published: November 2006

AbstractThe quantitative relationship between the structure of 2‐(arylimino) thiazolidines (AITs), arylethanolamines (AEAs) and 2‐(arylalkylamino)‐2‐thi‐azolines (AATs) and their octopamine (OA)‐agonist activities against the ventral nerve cord of American cockroach, Periplaneta americana L., was analysed using reported physicochemical parameters and regression analysis. The electronic nature of a substituent was the most important factor for AAT, followed by the hydrophobic effects: the more electron‐donating and the more hydrophobic the substituent, the greater the activity. The hydrophobic nature of a substituent in AEA was the most important factor, followed by the steric effects: the more hydrophobic the substituent, the greater the activity. The more electron‐donating the substituent of AIT, the greater the activity.
Synthesis and herbicidal activity of substituted tetrahydronaphthalenes: I
Authors: Parlow John J. , Mahoney Martin D. 
Published: November 2006

AbstractThis paper reports the synthesis and the biological activity of substituted 6‐alkyl‐1,2,3,4‐tetrahydro‐1,1‐dimethylnaphthalenes in which the substituents at the 5‐ and/or 7‐position are varied with a multitide of functional groups. These compounds exhibited pre‐emergent herbicidal activity which was a function of the electron‐withdrawing ability and the size of the groups substituted at the 5‐ and/or 7‐position. Nitro and/or nitrile groups at these positions tended to optimize activity.
Evaluation of a broad variety of coumarins, chromones, their furohomologues and thione analogues as phototoxins activated by UVA and visible light
Authors: Borges Marta L. , Matos Olivia C. , Pais Isabel , De Melo J. Seixas , Ricardo Cǎndido P. , MacAnita António , Becker Ralph S. 
Published: November 2006

AbstractThe potential of a new kind of light‐induced pesticide action was evaluated for a broad variety (32) of natural photosensitizers and their thione derivatives. The latter were synthesized to shift the absorption spectra towards the visible region and to increase the triplet and singlet oxygen quantum yields.Qualitative and quantitative evaluation of growth inhibition of Fusarium culmorum (F. G. Smith) Sacc. produced by these photosensitizers under UVA and visible light was performed on silica gel plates and in liquid medium. The results show that the phototoxicity per excited molecule of the thione derivatives using UVA light was similar to that of their parent natural compounds. On the other hand, only the thione derivatives were photoactive under visible light irradiation.These compounds show encouraging levels of phototoxicity against F. culmorum, both in liquid culture and on silica plates, and may have potential for use as photoactive pesticides.