bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fenitrothion‐induced alterations in ammonia metabolism in the crab, Oziotelphusa senex senex fabricius
Authors: Reddy Pamanji Sreenivasula , Bhagyalakshmi Avilala 
Published: November 2006

AbstractFresh water crabs, (Oziotelphusa senex senex) were subjected to short‐term (1 day) and long‐term (30 days) exposure to a sublethal concentration of fenitrothion (0.04 mg litre‐1), and the hepatopancreatic nitrogen metabolism was investigated. Differential patterns of nitrogen metabolism were observed in the hepatopancreas in response to both short‐term and long‐term exposure. Levels of ammonia in hemolymph of crab after short‐term exposure were markedly increased, with an increase in excretion of ammonia. The activity levels of aspartate aminotransaminase (AAT), alanine aminotransaminase (AIAT) and glutamate dehydrogenase (GDH) were found to increase in the hepatopancreas during short‐term exposure, which suggests increased transamination and deamination of amino acids. The AMP‐deaminase activity increased in the hepatopancreas during short‐term exposure indicating increased deamination of nucleic acids. The activity levels of ornithine cycle enzymes such as arginino succinate synthetase (ArSS) and arginase indicated diminished activities resulting in a low level of operation of the urea cycle and consequent accumulation of ammonia during short‐term exposure. The whole view of ammonia production and utilization mechanisms suggests the probable synergistic manifestation of ammonia toxicity during short‐term fenitrothion poisoning.However, during long‐term exposure, the haemolymph had a low ammonia level. The excretion of ammonia was also found to decrease. The activity levels of AAT, AIAT and GDH in the hepatopancreas were found to increase. In contrast to these, the AMP‐deaminase activity decreased in the hepatopancreas suggesting decreased deamination of nucleic acids. ArSS and arginase activities increased indicating active operation of the urea cycle and consequent accumulation of urea. Glutamine synthetase activity rose with the accumulation of glutamine which may help in averting toxic effects of ammonia. The possible effects of fenitrothion toxicity on energy requirements, transdeamination patterns, ureogenesis and glutamine production have been discussed.
Evaporation and Uptake of the Herbicide 2,4‐ D‐Butyl Applied to Barley Leaves
Authors: Breeze Victor G. , Simmons Joanna C. , Roberts Matthew O. 
Published: November 2006

AbstractSimultaneous measurements were made of evaporation and foliar uptake of formulated [2‐14C]2,4‐D‐butyl, applied as 10‐μl droplets to the leaves of three‐week‐old barley plants, at different temperatures and boundary layer conductances using an air‐flow system. Evaporation was measured both by trapping the vapour and by the difference between the amount applied and the amount recovered from the plant. Assimilation of vapour by the plants during the experimental periods of about 6 h was found to be about 0·4% of the total amount of herbicide applied initially to the leaves. Uptake and evaporation were described in terms of rates and velocity constants. Uptake was generally the more rapid, by about 2·5 times, of the two processes. Temperature affected evaporation strongly whereas uptake was largely unaffected. Kinetics of evaporation from glass slides and leaf surfaces were very similar if surface temperature was taken into account. Evaporation from leaves increased in darkness and in conditions of high boundary layer conductance caused by rapid air circulation. The importance of the boundary layer has been underestimated in previous studies, and some misleading results have been reported as a consequence. Most of the herbicide that penetrated the plant (95%) remained in the leaf to which it was applied, but it affected physiological processes within the plant because transpiration and carbon dioxide exchange were reduced by about 8 and 18%, respectively. Comparison with published values of herbicide uptake suggested that 2,4‐D‐butyl is relatively rapidly taken up by barley leaves. Results predicted that, at 27°C, about 30% of the 2,4‐D‐butyl sprayed onto barley leaves would evaporate, and 70% would remain in the plant.
Knowledge‐based systems for pest management: an applications‐based review
Authors: Edwards‐Jones Gareth 
Published: November 2006

AbstractSince the first application of artificial intelligence (AI) techniques to agricultural problems in 1982 nearly 300 further systems have been reported, of which 50 have been developed for pest management. Typically, these systems perform one of three tasks; diagnostics, treatment prescription or strategy development. The characteristics of all three types of system are discussed with reference to several examples. Although these examples serve to emphasise the power of AI techniques for aiding management decisions, few existing agricultural knowledge‐based systems utilise this potential to the full, and as yet there has not been a widespread adoption of this technology by practising pest managers. Despite the failure to transfer this technology from the laboratory to the field, the potential of knowledge‐based systems is widely recognised. However, further development of this technology for agricultural use within the UK is likely to be hindered by funding constraints.
Aspergillus niger and a Penicillium sp. are not directly involved in the degradation of chlorsulfuron
Authors: Stevens Melita , Duxbury Trevor 
Published: November 2006

AbstractWhen Aspergillus niger or a Penicillium sp. were grown in potato dextrose broth supplemented with chlorsulfuron, the herbicide concentration decreased by 97–99% within 78–96 h and the pH of the medium fell from 7.2 to between 2.4 and 3.1. If, during growth, the pH was maintained at or near neutrality, no decrease in herbicide concentration occurred. When sterile medium containing the herbicide was titrated with acid to mimic acid formation during fungal growth, the herbicide concentration again declined. Precipitation was not responsible for the observed decrease. The data indicate that, in laboratory media, these fungi do not directly metabolise the herbicide as previously thought. Chlorsulfuron degradation in perfused soil cores was not enhanced by inoculation with A. niger. Our results show that A. niger and a Penicillium sp. do not degrade chlorsulfuron.
Comparison of the impact of a neem seed‐kernel extract formulation, “Margosan‐O” and chlorpyrifos on non‐target invertebrates inhabiting turf grass
Authors: Stark John D. 
Published: November 2006

AbstractSeveral laboratory studies have indicated that neem seed‐kernel extracts, or the neem insecticide azadirachtin, are active against certain types of pestiferous insects but do not harm several types of beneficial arthropods. The abundance of several groups of invertebrates inhabiting a turf grass ecosystem was determined in 1991 after application of a neem‐based insecticide formulation, “Margosan‐O®” (MO; W. R. Grace & Co., Columbia, Maryland, USA) containing 3.0 g litre−1azadirachtin, and chlorpyrifos. MO was less detrimental than chlorpyrifos to most of the invertebrates studied. However, oribatid mites were more sensitive to MO than to chlorpyrifos. Sminthurid and non‐sminthurid collembola were also susceptible to MO, although less so than to chlorpyrifos. MO had no significant effect on non‐oribatid mites and spiders. Environmental implications of using selective versus broad‐spectrum insecticides in agriculture are discussed.
Biological control in protected crops: Where do we go?
Authors: Van Lenteren Joop C. 
Published: November 2006

AbstractBiological pest control is a reliable method and an economically profitable endeavour for growers of greenhouse crops. The fast evaluation and introduction of a number of natural enemies in situations where chemical control was either insufficient, impossible or undesired, has taught crop protection specialists that biological control, within IPM programmes, is a powerful option in pest control. Commercially available natural enemies are listed, current research in biological control is described, incorrect criticism of biological control is discussed and specific advantages of using this control method in protected crops are given.
Elevated humidities for control of chrysanthemum pests with Verticillium lecanii
Authors: Helyer Neil , Gill Graeme , Bywater Andy , Chambers Richard 
Published: November 2006

AbstractIntegrated pest control on chrysanthemum is now a possibility. Verticillium lecanii (Zimm.) Viegas is one of the key components as, under the right conditions, it will provide good control of pests such as aphids, thrips and whitefly. High humidity for a number of nights per week is critical for reliable pest control with this fungal pathogen. These conditions can be easily and safely obtained by fogging water over the crop at night. Four consecutive nights of high humidity per week or a cycle of two nights of high humidity and two nights ambient have given excellent pest control with no adverse effect to the crop.
Economics of integrated pest control in protected crops
Authors: Mumford John D. 
Published: November 2006

AbstractDecision‐makers in the protected crop environment face similar pest‐management decisions, in economic terms, to growers of field crops or grain store managers. As a result, the principles of economic thresholds, cost: benefit analyses and risk minimisation apply equally to each of these systems. Growers are faced with several general classes of pest‐control decisions: the general control strategy to adopt, and then tactical questions such as when to start control and when to stop or change control practices. However, there are a number of aspects of protected crops which require a somewhat different view of the problem. Several economic models for these questions are examined.The high density of protected crops means that a great deal is at risk at any one time. The protected environment reduces uncertainty about losses, but by optimising temperatures and humidities it increases the probability of loss. The feeling of being able to “control” the environment may extend to pests as well, increasing the use of standard pesticide or biocontrol programmes, rather than responsive pest management based on thresholds.The relatively small scale of protected crops, their accessibility for inspection and the high level of management skills involved in their production improve prospects for monitoring and predicting crop levels, insects and diseases, thus reducing uncertainty. However, the high probability of loss may reduce the value of gathering information, and encourage growers to rely on standard prophylactic procedures which allow them to devote management effort to more productive activities, such as marketing.The balance may be shifted towards more information‐based decisions in the future to try to avoid excessive pesticide use because of more stringent regulations on pesticide residues and changing market demand for more organic produce. This may affect disease control in particular, where prophylactic biological control is not an option.At the policy level, feedback on environmental impacts to consumers and policy‐makers is poor and decisions with expensive implications for the economy and for environmental quality may not be made in an optimal manner.
Determination of unchanged residues of a pyrethroid insecticide, PYR‐VU‐TO2, in sheep internal organ tissues
Authors: Oriňák Andrej 
Published: November 2006

AbstractDuring subacute toxicological testing of PYR‐VU‐TO2, a novel cypermethrin‐like pyrethroid with a high (150:1) cis: trans ratio, its distribution in skeletal muscle and internal organ tissues of two groups of experimental sheep was investigated after oral administration of two different doses (1/10 and 1/20 of the LD10). Residual levels of PYR‐VU‐TO2 were also observed in sheep blood after administration of a single dose of the compound.Homogenized internal organ tissues and blood samples were extracted in light petroleum distillate+acetone for 15 min. After filtration, the extract was cleaned up on a ‘Florisil’R and sodium sulfate layer.The pyrethroid elution was processed with acetone+light petroleum distillate (2+98 by volume).Recoveries ranged from 80.7 to 93.5%.Unchanged PYR‐VU‐TO2 residues were determined on a 1.5‐m stainless steel packed column under isothermal conditions with an electron‐capture detector. The results were evaluated by the calibration curve method. The coefficients of variation were generally lower than 5% and determination limit for PYR‐VU‐TO2 was 20 μg kg−1.Mean unchanged PYR‐VU‐TO2 residues lay within a wide range. After six weeks of treatment the following order of tissue residue levels could be stated: heart>lung>muscle>spleen>kidney>liver>brain, and spleen>muscle>lung>heart>liver>kidney>brain for experimental groups I and II, respectively.Only small differences between the residues in the tissues of males and females were found in the first group (daily PYR‐VU‐TO2 dose of 50 mg kg−1 live weight). The experimental females of the second group (daily PYR‐VU‐TO2 dose of 200 mg kg−1 body weight) revealed higher levels (other than spleen) than did the males. Maximum PYR‐VU‐TO2 residues in sheep blood were found 24 h after administration of a single dose.Confirmation of the results was carried out by determination of 3‐(2,2‐dichlorovinyl)‐2,2‐dimethylcyclopropanecarboxylic acid methyl ester by capillary GC.
Action of deltamethrin on the calcium/calmodulin‐dependent protein kinase from the rat brain
Authors: Enan Essam , Matsumura Fumio 
Published: November 2006

AbstractThe action of deltamethrin on the calcium/calmodulin‐dependent protein kinase (CaM‐Kinase II) and phosphatase system in the rat brain synapse was studied under various experimental conditions to optimize these enzyme activities and to facilitate the studies of the mechanism of interaction of this pesticide with several components of this enzyme system. To obtain a clear‐cut inhibition of this enzyme by deltamethrin the following conditions must be met: (a) the enzyme system should be purified by precipitation with ammonium sulfate (450 g litre−1) prior to the addition of deltamethrin, (b) both Ca2+and calmodulin (CaM) should be added to the incubated media before the addition of [y‐32P]ATP, (c) deltamethrin should be incubated at least 10 min (but less than 30 min) with the enzyme system before [y‐32P]ATP addition, (d) the incubation temperature should be above 20°C (optimum 30°C), (e) [y‐32P]ATP concentration should be in the order of 10−M(concentration adjusted using cold ATP), and (f) the incubation time with [y−P]ATP for incorporation of32P into the protein should be in the neighborhood of 60 s. Under these conditions, the inhibitory potency of various active and inactive isomers or analogs of pyrethroids and DDT was tested. The order of the inhibitory power of these active forms of pesticides was 1R‐deltamethrin > (S)(RS) fenvalerate ≥p,p′‐DDT. Other compounds were not active at the concentration tested, indicating the differential sensitivity of this enzyme and the existence of a correlation of inhibitory power to insecticidal activity.
Phloem translocation of strong acids—glyphosate, substituted phosphonic and sulfonic acids—in Ricinus communis L
Authors: Bromilow Richard H. , Chamberlain Keith , Tench Allen J. , Williams Roger H. 
Published: November 2006

AbstractThe mobility in phloem of several substituted phosphonic acids and a sulfonic acid was studied in the castor bean plant, Ricinus communis L. For a series of14C‐labelled phosphonate mono‐esters applied to the petioles of mature leaves, phloem transport was modest, becoming poor over longer distances in the plant. Substituted phenylphosphonic acids were more efficiently moved in phloem; uptake from the petiole and subsequent redistribution were slow, but these dibasic compounds were very stable in plants and substantial amounts reached the roots after 72 to 120 h. Glyphosate was very efficiently transported to phloem sinks even within 24 h, with high concentrations in phloem sap. Toluene‐4‐sulfonic acid moved predominantly in the xylem to the mature leaves and its phloem transport was poor. Transport patterns are considered in relation to the physico‐chemical properties of the compounds. Ion trapping appears to play little part in the phloem transport of these strong acids, though the good accumulation and transport in phloem of the complex molecule glyphosate cannot at present be explained.
Assessment of a mathematical model to predict spray deposition under laboratory track spraying conditions. II: Examination with further plant species and diluted formulations
Authors: Grayson B. Terence , Pack Simon E. , Edwards Dean , Webb James D. 
Published: November 2006

AbstractMean spray depositions onto leaves of five plant species (Zea mays L., Vicia faba L., Sinapsis alba L., Glycine max (L.) Merr, Vitis vinifera L.) were measured following spraying of an array of 36 solutions of acetone + aqueous “Triton X‐100” varying systematically in composition and properties. The spraying was carried out on five occasions using a standard laboratory track sprayer delivering the equivalent of 600 litre ha−1 onto a plane surface around plant height. The results, plotted as response surfaces, showed that there was little variation in spray deposition with solution composition for V. vinifera, there were some slight decreases in deposition with increase in “Triton X‐100” concentration on V. faba and S. alba, though not with increase in acetone concentration, and that there were slight systematic increases for G. max and large systematic increases for Z. mays with increase in acetone and “Triton X‐100” up to concentrations of 350 ml litre−1 and 0.5 g litre−1 respectively. At higher concentrations of these components, there were no further increases in deposition on these latter species.The results were in agreement with those predicted by a mathematical model derived previously, with the exception of the slight decreases in deposition on V.fana and S.alba and smaller increases in deposition than predicted on G.max. The decreases in deposition on the former species were attributed to slight run‐off from their easy‐to‐wet leaves at the higher “Triton X‐100” concentrations at the spray volume rate (600 litre ha−1) used. The poor fit of the observed and predicted spray depositions on G. max was attributed to the nature of its leaves. These are hairy and it is speculated that the fine hairs, rather than the true leaf surface, played a major role in capturing the small spray drops (115‐130 μm) created by the laboratory sprayer used in this work.The observed and predicted spray depositions with a set of diluted commercial‐type formulations were in good agreement for Setaria viridis (L.) Beauv., Pisum sativum L., Z. mays, with correlation coefficients (r) of 0.985, 0.988 and 0.935 respectively, and also for the more constant depositions on the easy‐to‐wet species Beta vulgaris L., but slightly less so for Triticum aestivum L. (r = 0.886) in this test. Overall the model was well‐behaved, giving a good prediction of the variation in spray deposition on leaves of a range of plant species, provided that these were not extensively hairy, with variation in the dynamic surface tension of the spray solution.
Development of a predictive uptake model to rationalise selection of polyoxyethylene surfactant adjuvants for foliage‐applied agrochemicals
Authors: Stock David , Holloway Peter J. , Grayson B. Terence , Whitehouse Paul 
Published: November 2006

AbstractComposition‐concentration relationships between a series of C13/C14polyoxyethylene primary alcohol (AE) surfactants and the foliar uptake enhancement of five model neutral organic compounds were examined in factorially designed experiments on wheat (Triticum aestivumL.) and field bean (Vicia fabaL.) plants grown under controlled environment conditions. Model compounds were applied to leaves asc.0.2‐μl droplets of 0.5 g litre−1solutions in aqueous acetone in the absence or presence of surfactants at 0.2, 1 and 5g litre−1. Uptake of the highly water‐soluble compound, methylglucose (log octanol‐water partition coefficient (P) = ‐ 3.0) was best enhanced by surfactants with high E (ethylene oxide) contents (AE15, AE20), whereas those of the lipophilic compounds, WL110547 (log P = 3.5) and permethrin (log P = 6.5), were increased more by surfactants of lower E contents, especially AE6. However, there was little difference between AE6, AE11, AE15 and AE20 in their ability to promote uptake of the two model compounds of intermediate polarity, phenylurea (log P = 0.8) and cyanazine (log P = 2.1). Absolute amounts of compound uptake were also influenced strongly by both surfactant concentration and plant species. Greatest amounts of uptake enhancement were often observed at high surfactant concentration (5 g litre−1) and on the waxy wheat leaves compared with the less waxy field bean leaves. The latter needed higher surfactant thresholds to produce significant improvements in uptake. Data from our experiments were used to construct a simple response surface model relating uptake enhancement to the E content of the surfactant added and to the physicochemical properties of the compound to be taken up. Qualitative predictions from this model might be useful in rationalising the design of agrochemical formulations.
Association between insecticide use and greenhouse whitefly (Trialeurodes vaporariorum westwood) resistance to insecticides in hawaii
Authors: Omer Amir D. , Johnson Marshall W. , Tabashnik Bruce E. , Ullman Diane E. 
Published: November 2006

AbstractSusceptibility to acephate, methomyl, and permethrin was determined with laboratory bioassays for adults of greenhouse whitefly, Trialeurodes vaporariorum Westwood, from 12 to 14 sites in Hawaii. Comparisons at LC50 showed up to 42‐fold resistance to acephate, 36‐fold resistance to methomyl, and 8‐fold resistance to permethrin. Higher levels of resistance to acephate and methomyl than to permethrin are consistent with greater use of organophosphates and carbamates than pyrethroids by growers. Insecticide use varied from 1 to 98 insecticide sprays per site per season. Significant positive associations between LC50 for each insecticide and frequency of application of the same insecticide were found across sites. This finding suggests that local variation in insecticide use was an important cause of variation in susceptibility.
The activation of nicotinic acetylcholine receptors in the nematode parasite Ascaris suum by the application of levamisole to the cytoplasmic surface of muscle membrane
Authors: Robertson Susan J. , Martin Richard J. 
Published: November 2006

AbstractThe patch‐clamp technique was used to examine activation by levamisole of nicotinic acetylcholine receptors in muscle vesicle preparations from Ascaris suum. Previous experiments have shown that levamisole, when applied at concentrations greater than 30 μM to the extracellular surface of the membrane, activated channels which showed characteristics of a voltage‐sensitive open channel‐block and desensitisation. In this study initial experiments were performed where channels were activated with levamisole (2 μM) applied in the patch‐pipette. Isolated inside‐out patches were used. In addition, levamisole (30‐926 μM) was added to the cytoplasmic membrane surface via the bath solution. In eight out of nine experiments, addition of levamisole to the bath solution resulted in an increase in channel activity, a voltage‐sensitive open channel‐block and desensitisation. The open channel‐block occurred at hyperpolarised potentials, an observation consistent with levamisole (a cationic substance) blocking the channel from the extracellular surface. Thus it was concluded that levamisole crossed from the cytoplasmic side of the membrane, via the lipid phase, to the extracellular surface of the patch. In the presence of high cytoplasmic concentrations of levamisole, open channel‐block was not observed at depolarised potentials, suggesting channel asymmetry.