bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological control in protected crops: Where do we go?
Authors: Van Lenteren Joop C.
Published: November 2006

Biological 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

Integrated 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

Decision‐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

During 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

The 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

The 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

Mean 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

Composition‐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

Susceptibility 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

The 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.
Thiazole carboxanilide fungicides: A new structure—activity relationship for succinate dehydrogenase inhibitors
Authors: Phillips W. Gary , Rejda‐Heath Joan M.
Published: November 2006

Structure‐activity relationships have been examined for a series of thiazole carboxanilides as inhibitors of succinate dehydrogenase. Electron withdrawing and lipophilic effects are important parameters with regard to the anilide ring. Electron‐withdrawing effects along with steric limitations are also important in the thiazole 2‐position. Maximization of this unique structure activity relationship led to the synthesis of the most powerful succinate dehydrogenase inhibitors yet reported. This succinate dehydrogenase inhibitory activity was found to translate directly to high fungitoxicity toward Rhizoctonia solani (Kuhn).
Influence of some nonionic surfactants on water sorption by isolated tomato fruit cuticles in relation to cuticular penetration of glyphosate
Authors: Coret Joël M. , Chamel André R.
Published: November 2006

The effects of several nonionic surfactants on [14C]glyphosate mono(isopropylammonium) diffusion across isolated tomato fruit cuticles (Lycopersicon esculentum Mill.) were compared under controlled atmospheric conditions (25°C; 65% R.H.) using a model system consisting of 1‐μl droplets applied to isolated cuticles on agar blocks. Rates of diffusion for glyphosate (10 g acid equivalent litre−1 in the applied solution) and overall amounts recovered in underlying agar blocks were influenced by the ethylene oxide (EO) chain length for a homologous nonylphenol surfactant series (10 g litre−1). Glyphosate uptake increased with EO content, reaching an optimum at a mean of 17 EO, then decreasing below control values for surfactants with 40 EO. There was a strong influence of the hydrophobe on glyphosate penetration for different surfactants with similar mean EO content (10 EO). The primary aliphatic amine enhanced penetration the most, followed by the nonylphenol while the aliphatic alcohol showed no improvement on glyphosate transfer across cuticles.

Water soprtion was greatly enhanced by a primary aliphatic amine (10 EO) and by a nonylphenol (17 EO). The aliphatic alcohol (10 EO) and a shorter‐chained nonylphenol (4 EO) did not significantly enhance water sorption.

Comparison of water sorption with glyphosate diffusion across cuticles suggests a strong relationship between the two. Change in solution pH over a limited range had no significant effect.

Promotion of cuticular hydration by surfactants may thus play an important role in the enhancement of foliar uptake of water‐soluble herbicides such as glyphosate.
Growth inhibitory and antifeedant effects of azadirachtin on six noctuids of regional economic importance
Authors: Isman Murray B.
Published: November 2006

The comparative efficacy of azadirachtin, the major active ingredient in the botanical insecticide neem, as a larval growth inhibitor and feeding deterrent was determined for six species of noctuids of economic importance: the black army cutworm, Actebia fennica (Tausch.), the bertha armyworm, Mamestra configurata Walker, the variegated cutworm, Peridroma saucia Hubner, the zebra caterpillar, Melanchra picta (Harr.), the Asian armyworm, Spodoptera litura (Fab.), and the cabbage looper, Trichoplusia ni Hubner. When added to an artificial diet, azadirachtin inhibited neonate larval growth of all species in a dosedependent fashion. EC50 values (dietary concentration reducing larval growth by 50% relative to controls) following ten days of feeding ranged from 0.12 to 0.24 mg kg−1 but without significant differences between species. However, when second‐instar larvae were offered a choice, only larvae of P. saucia and S. litura discriminated between a control diet and diet containing azadirachtin at concentrations up to 0.4 mg kg−1. A more sensitive behavioural bioassay using fourth‐instar larvae indicated that S. litura was the most sensitive to the antifeedant effects of azadirachtin (EC50 = 1.25 ng cm−2), whereas A. fennica was the least (EC50 = 40.7 ng cm−2). Topical treatment of fourth‐instar larvae with 50 or 100 ng of azadirachtin resulted in significant inhibition of subsequent growth, diet consumption, and dietary utilization. However, A. fennica and S. litura are less inhibited that the other four species. The present study indicates that behaviourbased bioassays alone do not characterize the total effect of azadirachtin on noctuid larvae.
Adjuvants and volatility of hormone herbicides
Authors: Schubert Christine L. , Erasmus Daniel J. , Van Dyk Louis P. , Gray Vincent , Lovell Kevin
Published: November 2006

The aim of this study was to develop a rapid and reliable method for detecting the effect of adjuvants on the volatility of herbicides and to assess the efficacy of locally available adjuvants. Bioassays, using seed germination, were unsatisfactory for assessing the reduction of the volatility of the iso‐octyl ester of 2,4‐dichlorophenoxyacetic acid (2,4‐D IOE) by adjuvants.

Field trials and parallel trials under controlled conditions, together with chromatographic analyses of trapped herbicide vapour, were effective in assessing the efficacy of adjuvants. The adjuvants used were: a molasses‐based developmental sample of a feeding attractant and antidrift agent; a wax emulsion contributing to control of droplet size; an anionic gel‐based sticker and spreader made from kelp; an alkoxylated‐fatty alkylamine polymer marketed as a wetter and penetrator; an aqueous dispersion of waxes and surfactants which reduces drift and evaporation; a polyvinyl polymer for drift reduction; an emulsifiable beta‐pinene polymer and two different formulations of an adjuvant with buffering action. Experimental grass plots were sprayed with herbicide with or without adjuvants (used as controls). 2,4‐D vapour in the air above the plots was sampled and analysed by gas chromatography. Field trial results indicated that weather factors influenced the volatility of 2,4‐D IOE and that only the polyvinyl polymer decreased volatility for the duration of the trial. The adjuvant consisting of a dispersion of waxes and surfactants had no effect on the volatility of 2,4‐D IOE. The molasses‐based, wax emulsion, and beta‐pinene polymer‐based adjuvants caused an initial increase in 2,4‐D IOE vapour, but the volatility decreased after two hours. Trials performed in a portable glasshouse showed similar results, and also showed that a new formulation of an existing adjuvant with buffering action reduced volatility.
Design and synthesis of 5,6‐dihydro‐4H‐1,3,4‐oxadiazines as potential octopaminergic insecticides
Authors: Dekeyser Mark A. , Harrison W. Ashley , McDonald Paul T. , Downer Roger G. H.
Published: November 2006

A novel class of insecticides, the dihydrooxadiazines, was proposed following the use of molecular modelling techniques. These compounds represent conformationally restricted analogues of octopamine. Eight dihydrooxadiazines were synthesized and evaluated for useful insecticidal properties. Several of these compounds demonstrated activity against rice planthoppers, mite eggs, and tobacco budworm eggs.
Biological monitoring of workers occupationally exposed to organophosphorus pesticides
Authors: Nutley Bernard P. , Cocker John
Published: November 2006

This paper describes the development and use of a biological monitoring method for assessing exposure to organophosphorus pesticides. The method is used to determine the concentration of six dialkyl phosphates and phosphoro‐thioates (dimethyl phosphate, diethyl phosphate, O,O‐dimethyl phosphorothioate, O,O‐diethyl phosphorothioate, O,O‐dimethyl phosphorodithioate and O,O‐diethyl phosphorodithioate) in urine. The method involves the azeotropic distillation of urine, derivatisation of the residue with pentafluorobenzylbromide followed by high resolution gas chromatography with flame photometric detection.

The technique has been applied to the analysis of over 400 urine samples obtained from 140 workers with potential occupational exposure to organophosphorus pesticides during various agricultural activities, sheep dipping or pesticide formulation. Wherever possible, blood samples were taken for measurement of red blood cell and plasma cholinesterase activity. The results show that in over 300 instances where blood samples were also obtained, urinary dialkyl phosphate metabolites could be detected even though there was no depression of red cell or plasma cholinesterase activity. Formulation workers had higher urinary metabolite levels (expressed as nmoles metabolite per mmole creatinine) than any of the other groups studied and were the only group where a significant reduction in cholinesterase activity was also seen.

The results discussed here show that the method for the analysis of urinary dialkyl phosphate metabolites described is useful for monitoring occupational exposure to organophosphorus pesticides and is capable of detecting low levels of exposure not detectable by depression of cholinesterase activity.
Pesticidal compounds from higher plants
Authors: Benner Jill P.
Published: November 2006

Higher plants offer an excellent source of biologically active natural products. Over the centuries numerous plants have been exploited as sources of insecticides, but nowadays traditional botanical insecticides play only a minor role in world agriculture. Nevertheless, plant natural products still have enormous potential to inspire and influence modern agrochemical research.

Few plant natural products will ever reach the market as products per se, but others will provide lead structures for programmes of synthetic chemistry and hopefully follow the success story of the synthetic pyrethroids. Structurally complex compounds, which are not amenable to synthetic chemistry programmes, may also have a role to play by validating new modes of action for pesticides.

Examples are presented of compounds exhibiting insecticidal, fungicidal and herbicidal effects. Consideration is also given to the development of screening programmes to detect new compounds with interesting biological properties. Careful experimental design and thorough recording of procedures and data are crucial to success. Badly designed programmes afford only weakly active compounds or show effects which cannot be reproduced at a later date.

Natural product chemistry, whether based on higher plants, micro‐organisms or other sources, is a very difficult science, but there is little doubt that dedicated research will eventually be rewarded with exciting new lead structures for industrial application.
Genetically engineered viral insecticides: New insecticides with improved phenotypes
Authors: Possee Robert D. , Cayley P. Jane , Cory Jenny S. , Bishop David H. L.
Published: November 2006

Baculoviruses are natural pathogens of insects which have been used as biopesticides. In contrast to many chemical agents, baculoviruses affect only a limited number of insects and so can be used to target particular insect species. Unfortunately, unless the host receives a very high virus dose, the insect continues to feed and causes damage to crops, because the virus takes several days to kill it. This lag is unacceptable in the protection of many crops, especially where cosmetic damage seriously reduces the value of a crop (e.g. fruit). Strategies have been devised recently to circumvent this problem. The baculovirus genome has been modified, using genetic engineering techniques, to incorporate foreign genes encoding insect‐specific toxins, or hormones or enzymes. Expression of some of these genes in the virus‐infected host insect has been shown to reduce both the feeding damage to crop plants and the time taken to kill the insect pest. The current status of this developing field is described, together with an assessment of the possible risks involved in using such genetically modified agents in the environment.
Uptake and translocation of bleaching herbicidal compounds in radish seedlings
Authors: Takahashi Masahiro , Kawamura Shinichi , Miyakado Masakazu , Sanemitsu Yuzuru , Tanaka Shizuya
Published: November 2006

The relationship between the hydrophobicity of certain herbicidal compounds and the bleaching pattern caused on radish cotyledons was investigated. Seed treatment with diphenylpyridones, as well as with established herbicides, produced three types of bleaching pattern according to their hydrophobicity. The less hydrophobic compounds caused complete bleaching of both cotyledons, but the compounds with more hydrophobicity caused only partial bleaching. The critical points for whole or partial bleaching were in the range of log Kow 4–5 (Kow: octanol/water partition coefficient), and these values were changed slightly with their chemical classes. Uptake of compounds into the seed coat took place rapidly; these compounds were then translocated slowly from the seed coat to the embryo, namely, radicle, abaxial surface of one cotyledon and marginal areas of both cotyledons.

Application of these compounds to roots resulted in initial translocation to marginal areas of both cotyledons, with subsequent translocation to the middle area. It is believed that compounds taken up into the radicle were translocated to both cotyledons in a manner similar to that following application to roots. These effects following uptake by seeds can be used as a translaminal and lateral transport assay for bleaching herbicidal compounds in cotyledons.
Effects of alcohols, glycols and monodisperse ethoxylated alcohols on mobility of 2,4‐D in isolated plant cuticles
Authors: Schönherr Jörg
Published: November 2006

Effects of n‐alcohols, ethoxylated alcohols and glycols on mobility of 2,4‐dichlorophenoxy acetic acid (2,4‐D) in cuticular membranes (CM) isolated from bitter orange (Citrus aurantium L.) leaves were studied. 1‐Heptanol, 1‐octanol and 1‐nonanol had the highest effects, as they increased solute (2,4‐D) mobility by 25‐ to 30‐fold. Increasing the number of carbon atoms in the alcohols decreased their effectiveness. Ethoxylation of alcohols did not increase 2,4‐D mobility and effectiveness decreased with increasing ethoxylation. Free glycols had no effect on solute mobility in isolated cuticles. The results show that ethoxylation is not required for increasing solute mobility in cuticles. It is suggested that alcohols and ethoxylated alcohols are sorbed in cuticular waxes and plasticize them. The data show that alcohols and ethoxylated alcohols having between seven and ten carbon atoms are powerful accelerator adjuvants, as long as the degree of ethoxylation is not too high. Free short‐chain alcohols synthesized by leaves may act as endogenous plasticizers and modulate permeabilities of cuticles, depending on environmental and growing conditions.
Influence of pesticides on the activity and kinetics of invertase, urease and acid phosphatase enzymes
Authors: Gianfreda Liliana , Sannino Filomena , Filazzola Maria T. , Violante Antonio
Published: November 2006

The effects of four pesticides (three herbicides, atrazine, paraquat, glyphosate, and an insecticide, carbaryl) on the activity and kinetics of an invertase (from yeast), a urease (from jack bean) and an acid phosphatase (from potato) were investigated. Glyphosate and paraquat showed a marked activation effect on invertase activity. From the dependence ofVmaxandKmparameters on pesticide concentrations, a mixed‐type activation mechanism was suggested. The kinetic behaviour of urease and acid phosphatase appeared to be uninfluenced by both pesticides.

Methanol, used as solvent for both carbaryl and atrazine, inhibited invertase, urease and acid phosphatase with, respectively, competitive, non‐competitive and uncompetitive mechanisms. The extent of the inhibition was different, as estimated by the values of the inhibition constantK1. An additional inhibition effect of urease and invertase activities was achieved in the presence of carbaryl, whereas no influence was detected on the activity and kinetics of acid phosphatase. Finally, atrazine was shown to alter the kinetics of the enzymes only at higher concentrations.
Effects of triazole inhibitors of sterol biosynthesis on the free and esterified sterol composition of celery cell suspension cultures
Authors: Yates Philip J. , Lenton John R. , Goad L. John
Published: November 2006

Treatment of celery cell suspension cultures with paclobutrazol and three other triazoles resulted in decreased growth and an accumulation of 14α‐methylsterols in both the free sterol and the steryl ester pools, thus indicating that the triazoles were inhibiting the action of the plant obtusifoliol 14α‐demethylase system. Obtusifoliol, 14α‐methylcampesta‐8,24(241)‐dien‐3β‐ol and 14α‐methylcampest‐8‐en‐3β‐ol were the main 14α‐methylsterols to increase in the free sterol pool. In the presence of the triazoles the steryl esters became virtually depleted of sitosterol, campesterol, stigmasterol and isofucosterol, which were replaced by 14α‐methylsterols with obtusifoliol becoming the dominant esterified sterol. Treatment of the celery culture with a fourth triazole which did not have a noticeable effect on growth and caused negligible accumulation of 14α‐methylsterols in the free sterol pool nevertheless produced some enrichment of the steryl esters in obtusifoliol. The results indicate that, following triazole treatment, a rapid esterification of the accumulating 14α‐methylsterol intermediates occurs before they start to build up in significant amount in the free sterol pool.
Effects of pyroquilon on the infection process of Monilinia laxa causing peach twig blight
Authors: De Cal Antonieta , Melgarejo Paloma
Published: November 2006

The capacity of Monilinia laxa (Aderh. et Ruhl.) Honey to induce peach twig blight was lost in an albino mutant and in a wild‐type strain of the pathogen treated with pyroquilon, a melanin biosynthesis inhibitor. Pyroquilon (10 ù ml−1) inhibited melanin biosynthesis but did not inhibit mycelial growth of the pathogen or the albino mutant in vitro. These observations indicate that the compound interferes in some manner with the infection process of host cells.
Evaluation of a pelleted bait containing methyl anthranilate as a bird repellent
Authors: Mason J. Russell , Clark Larry , Miller Timothy P.
Published: November 2006

No‐till agriculture involves the use of granular pesticide formulations, chemically treated seeds, and pelleted baits. Some of these may accidentally kill birds. We have tested whether methyl anthranilate (MA), a known bird repellent, would eliminate consumption of a pelleted bait. In two laboratory experiments and an outdoor aviary trial, cowbirds (Molothrus ater Bodd.) were presented with pellets containing pesticide and MA, pellets containing pesticide but no MA, and carrier pellets without pesticide or MA. Consumption of any formulation was low, but the addition of MA significantly decreased bait loss in the laboratory, and prevented the disappearance of bait in the outdoor trial.
Acute toxicity of the bird repellent, methyl anthranilate, to fry of Salmo salar, Oncorhynus mykiss, Ictalurus punctatus and Lepomis macrochirus
Authors: Clark Larry , Cummings John , Bird Steven , Aronov Eugeny
Published: November 2006

Several laboratory and field studies have shown methyl anthranilate to be an effective, non‐toxic and non‐lethal bird repellent, with application potential for protecting crops, seeds, turf and fish stocks from bird damage. Furthermore, methyl anthranilate can be added to liquids for the purposes of protecting migratory birds, e.g. addition to waste water associated with mining and to standing water pools at airports. Mammalian toxicity data are favorable. Methyl anthranilate is used as a fragrance and food flavoring and is GRAS listed by the US Food and Drug Administration. Despite the favorable outlook for methyl anthranilate's use as a safe repellent, no data exist on its environmental fate and effects. We have tested the acute toxicity of methyl anthranilate in a static system against the fry of four species of fish. The LC50 at 24 h for Atlantic salmon (Salmo salar L.) was 32.3 mg liter−1, with the no observable effect limit at 6 mg liter−1. The LC50 at 24 h for rainbow trout (Oncorhynus mykiss Richardson) was 23.5 mg liter−1, with the no observable effect limit at 5 mg liter−1. The LC50 at 24 h for channel catfish (Ictalurus punctatus Raf.) was estimated to be 20.1 mg liter−1, with the no observable effect limit at 7 mg liter−1. The LC50 at 24 h for bluegill sunfish (Lepomis macrochirus Raf.) was estimated to be 19.8 mg liter−1, with the no observable effect limit at 7 mg liter−1..
Selection and characterization ofPhytophthora parasiticamutants with ultraviolet‐induced resistance to dimethomorph or metalaxyl
Authors: Chabane Kamel , Leroux Pierre , Bompeix Gilbert
Published: November 2006

Mutants ofPhytophthora parasiticaDast. more or less resistant to dimethomorph or metalaxyl were obtained by treating mycelium with ultraviolet radiation. Some metalaxyl‐resistant mutants exhibited levels of resistance (i.e. the ratio between the EC50values for the mutant and the wild‐type strain) greater than 100, but those observed in the dimethomorph‐resistant mutants never exceeded 25. Most mutants retained their resistance after sub‐culturing on unamended agar medium. Single zoospore clones derived from a metalaxyl‐resistant and a dimethomorph‐resistant mutant, selected as amongst the most resistant, had levels of resistance similar to those of the parental strains. The metalaxyl‐resistant mutants were also resistant to the related phenylamide fungicides, furalaxyl and benalaxyl, but remained sensitive to dimethomorph. The dimethomorph‐resistant mutants were not resistant to phenylamide fungicides. The pathogenicity of some metalaxyl‐ or dimethomorph‐resistant mutants on tobacco leaves was similar to that of the wild‐type strains.
Potential of natural peptidic compounds as leads for novel pesticides
Authors: Bland John M. , Edwards J. Vince , Eaton Scott R. , Lax Alan R.
Published: November 2006

Structure‐activity relationship (SAR) studies of the natural pesticidal peptide, tentoxin, are described in the context of similarity between pharmaceutical and agricultural methods of developing biologically active peptidomimetics. Essential residue substitutions that confer biological activity through predictable conformational changes in the peptide backbone and side chain functionalities are discussed. A combination of molecular modelling studies and the biological activity of natural, synthetic and photochemically transformed analogs of tentoxin is utilized to further the understanding of structural and conformational requirements for biological activity.
Behavioural responses ofAphis fabaeto isothiocyanates in the laboratory and field
Authors: Isaacs Rufus , Hardie Jim , Hick Alastair J. , Pye Barry J. , Smart Lesley E. , Wadhams Lester J. , Woodcock Christine M.
Published: November 2006

Isothiocyanates have been shown to stimulate olfactory receptors on the antennae of the black bean aphid,Aphis fabaeScop. Single‐cell recording techniques show that this aphid has receptors at the proximal primary rhinarium which are sensitive to n‐butyl isothiocyanate. In laboratory assays, 4‐pentenyl and n‐butyl isothiocyanates were repellent at similar threshold concentrations.A. fabaewas attracted to host‐plant odour, but addition of either isothiocyanate to the airstream masked this attraction. Field trials on spring beans did not produce any consistent reduction in numbers of alate or apterous aphids on the crop, and yields were not improved by either compound.
Lipophilic, hydrolytic and photolytic properties and fungicidal activity against Botrytis cinerea of 1‐(4‐substituted phenoxymethyl)‐2, 2‐dimethylpropyl imidazole‐1‐carboxylates and ‐thiocarboxylates
Authors: Imai Tetsuya , Uchida Toshiro , Yamaguchi Kunio , Takao Hisashi , Goto Takeshi
Published: November 2006

The sterol 14α‐demethylation inhibitors 1‐(4‐substituted phenoxymethyl)‐2, 2‐dimethylpropyl imidazole‐1‐carboxylates and their corresponding thiocarboxylates were optimized for maximum in‐vitro activity against Botrytis cinerea Pers. ex Fr. in terms of the lipophilic parameter π. The activity of both carboxylates and thiocarboxylates was strongly related with π and predicted to be maximum at π 1.38 and 0.72 respectively. However, the preventive efficacy of the carboxylates against B. cinerea on Solanum melongena L. grown in a greenhouse did not correlate with the parameter. Despite the unfavourable lower lipophilicity, compounds with p‐alkoxy substituents were superior to those with any other substituent. Moreover, the p‐methoxy‐substituted thiocarboxylate 46 was much less effective in greenhouse tests than the corresponding carboxylate 15, despite their equivalent in‐vitro activity. To clarify these discrepancies, hydrolytic and photolytic stabilities of several representative compounds including 15 and 46 were investigated. The carboxylates examined were much more labile to hydrolysis than the thiocarboxylate 46; however, the four thiocarboxylates studied were less stable to light than the carboxylates. Consequently, the above discrepancies were attributable mainly to the superior stability of the carboxylates to photolysis as compared to the thiocarboxylates.
Assessment of field hazards to birds from methiocarb applications to fruit crops
Authors: Dolbeer Richard A. , Avery Michael L. , Tobin Mark E.
Published: November 2006

Methiocarb, a broad‐spectrum carbamate insecticide, has shown efficacy in repelling birds from a variety of crops, especially fruit. To evaluate the hazards posed to wildlife, we reviewed laboratory studies of methiocarb toxicity and repeilency to birds and mammals and field studies of methiocarb treatments to fruit and sweet corn. Calculations revealed that birds encountering typical maximum residue levels found in treated crops would have to eat extremely large amounts of treated food to die and would in almost all cases be repelled or immobilized long before a lethal dose could be ingested.

Results from feeding tests in laboratories support these calculations, as do the findings from 33 field studies in 28 locations. In spite of extensive searches and observations, only 14 dead birds were found in treated fields. Based on estimates from 26 studies, treated plantings averaged 15% loss of fruit to birds compared with 36% for nearby untreated plantings. We conclude that methiocarb, applied to fruit crops at 1–7 kg a.i. ha −1, will not adversely affect birds.
Study of the relation between carbofuran degradation and microbial or physicochemical characteristics of some french soils
Authors: Charnay Marie‐Paule , Fournier Jean‐Claude
Published: November 2006

In France, corn rootworm (Agriotes sp.) is controlled by applying insecticides such as carbofuran to the soil. In recent years, the failure of carbofuran to control this pest has been observed in the south‐west area of France in continuous corn cropping. A soil survey was conducted in order to determine the main factors which could influence carbofuran degradation in various soils. Degradation estimates were based on measurement of the release of [ 14 C]carbon dioxide from [carbonyl‐ 14 C]carbofuran. The enhanced degradation of carbofuran observed in laboratory conditions corresponded to the growth of micro‐organisms able to use carbofuran as sole carbon and nitrogen source. The size of this microbial population and the rates of carbofuran degradation were higher in the samples taken from plots with a history of carbofuran use than in samples from previously untreated plots. Abiological degradation was only observed in alkaline soil conditions. Statistical analyses showed that carbofuran‐degrading activity was not related to any particular pedological characteristics.
Insecticidal activity of new fluorinated pyrethroids and their stability toward chemical oxidation and photoreaction
Authors: Ando Tetsu , Koseki Nozomu , Yasuhara Isamu , Kasuga Kie , Matsuo Noritada , Ishiwatari Takao
Published: November 2006

The insecticidal activity of several new fluorinated pyrethroids was measured using houseflies untreated and treated with piperonyl butoxide (PB). 10, 10‐Difluorophenothrin and 10, 10‐difluoroallethrin, which include fluorine atoms at a position most easily attacked by mixed function oxidases (mfo) in the acid moiety, showed smaller topical LD50 values on the PB‐untreated flies than the parent insecticides but rather large values on the PB‐treated flies, suggesting that the introduction of fluorine prevents metabolic oxidation, although it has a negative effect on the interaction with a target site. Monofluorinated analogues of phenothrin, in which the structure of chrysanthemic acid was rearranged, still had moderate insecticidal activity, but flies were scarcely killed by 7 fluoroallethrin into which fluorine was introduced at a position most easily oxidized by mfo in the alcohol moiety.

Competitive oxidation of the fluorinated derivatives and the parent compounds showed that fluorine at both the 10‐ and 7′‐positions stabilizes the alkenyl side‐chains of the pyrethroids against selenium dioxide and m‐chloroperoxybenzoic acid. Photochemical studies with 10, 10‐difluorophenothrin indicated that the photo‐instability of the cyclopropanecarboxylic part could not be improved by this modification.
Responses of three species of captive fruit‐eating birds to phosmet‐treated food
Authors: Avery Michael L. , Nol Pauline , Humphrey John S.
Published: November 2006

We conducted two‐cup feeding trials to assess the responses of cedar waxwings (Bombycilla cedrorum (Vieillet)), American robins (Turdus migratorius (L.)), and European starlings (Sturnus vulgaris L.) to food adulterated with phosmet 500 g kg−1 WP (‘Imidan’®). All species avoided phosmet concentrations ⩾ 100 mg kg−1.Robins avoided food containing 60 mg kg−1 phosmet, while food consumption by starlings was reduced by a 30 mg kg−1 treatment. All species were indifferent to phosmet at 10 mg kg−1.

These findings suggest that fruit‐eating birds will safely avoid ingesting harmful levels of phosmet when the insecticide is applied to small fruit such as blueberries and cherries. Feeding deterrence associated with phosmet might be exploited in management strategies to protect small fruit crops from damage by birds.
Initial deposits and persistence of azadirachtin in fir and oak foliage after spray application of ‘Margosan‐O’® formulation
Authors: Sundaram Kanth M. S. , Curry Johanna
Published: November 2006

Foliar deposits and persistence of azadirachtin were investigated after spraying ‘Margosan‐O’® formulation at three dosage and volume rates on to balsam fir and oak seedlings in a laboratory chamber. Droplet‐size spectra and deposits were assessed using artificial samplers, and foliar residues were measured by high‐performance liquid chromatography (HPLC) at different intervals of time after treatment. Disappearance of azadirachtin from both types of foliage was rapid, and the DT50 (the time required for 50% of the initial concentration to disappear) values ranged from 17 to 22 h. The initial azadirachtin concentrations varied widely from 4 to 96 μg g−1 (fresh weight), but the rate constants 0.0311 to 0.0414, were not significantly different. The data thus indicated a poor relationship between initial concentrations and the rate of loss.

The influence of spray droplet size and cuticular wax content of foliage on persistence of azadirachtin was investigated using both foliar types, and glass microscope slides without and with the foliar wax coating. Neither the type of surface nor the droplet size influenced the persistence. The rate of azadirachtin loss from the glass slides was faster than from both types of foliage, and was unaffected by the presence of wax coating. The fir foliage had higher cuticular wax content than the oak foliage, but the persistance of azadirachtin was similar in both foliar types.