bluuebunny/crossref_metadata_2025 huggingface dataset:
Persistence of hexachlorocyclohexane isomers and carbofuran applied to surface and sub‐surface layers of a flooded soil
Authors: Panda Soudamini , Sharmila M. , Ramanand K. , Panda D. , Sethunathan N.
Published: November 2006

The persistence of carbofuran (2, 3‐dihydro‐2, 2‐dimethylbenzofuran‐7‐yl methylcarbamate) and the β‐ and γ‐isomers of HCH (hexachlorocyclohexane) applied to surface (oxidised) and sub‐surface (reduced) layers of a flooded soil was studied using radiolabelled insecticides. In one experiment, these compounds were placed in the surface (2–5 mm) and sub‐surface (10–15 cm) layers of 10‐day flooded soil columns. HCH isomers were unstable under flooded soil conditions irrespective of their placement, but disappeared slightly faster when applied to the sub‐surface layer, possibly due to the more reduced conditions prevailing. In contrast, sub‐surface‐applied carbofuran was more stable than surface‐applied carbofuran. The decreased stability of surface‐applied carbofuran may be due to a relatively higher pH in the surface layer and in the flood water which was in immediate contact with the surface layer. In another experiment, surface and sub‐surface soil samples were collected from a rice field which had been flooded for 30 days. These soils were then again flooded under laboratory conditions prior to addition of carbofuran and β‐HCH. Upon submergence, both surface and sub‐surface soil samples attained almost equally reduced conditions. In flooded surface soil samples, more rapid degradation not only of carbofuran but also of β‐HCH occurred, compared with similarly incubated sub‐surface soil samples.
The susceptibility of the Indian field mouse, Mus booduga gray, to anticoagulant rodenticidal baits
Authors: Balasubramanyam M. , Purushotham K. R.
Published: November 2006

The baseline susceptibility of the Indian field mouse, Mus booduga was established for warfarin, bromadiolone and brodifacoum by means of nochoice feeding tests. The mice were found to be more susceptible to the second generation anticoagulants bromadiolone (0.005 g kg−1) and brodifacoum (0.002 g kg−1) than warfarin (0‐25 g kg−1). They required 8–10 days feeding on warfarin (0.25 g kg−1) diet for complete mortality. A feeding period of 8 days corresponding to 99% mortality was suggested as a checking test for registering future warfarin resistance in suspect samples of M. booduga.
Virus recognition and pathogenicity: Implications for resistance mechanisms and breeding
Authors: Fraser Ronald S. S.
Published: November 2006

The major method of control of virus diseases in crop plants is breeding for resistance. The genetics of resistance, and of matching virulence (the ability of a virus strain to overcome a specific host resistance gene) have been studied less for viruses than for fungal and bacterial pathogens. This paper draws on a survey of the genetics of resistance to a large number of viruses in cultivated crops, and makes some generalisations and predictions about mechanisms.

Most resistance to viruses in crops is monogenic. Dominant alleles are associated with virus‐localisation mechanisms, which are induced after infection. The nature of the ‘recognition event’ between plant‐ and virus‐coded functions, which triggers resistance plus a cascade of secondary responses, is not yet known. Gene dosage‐dependent alleles tend to be associated with non‐localising resistance, which allows some virus spread, but inhibits multiplication. Recessive alleles may involve a negative type of resistance mechanism, whereby the resistant plant lacks some function normally required by the virus for pathogenesis. Such resistance tends to be expressed as complete immunity.

Many resistance genes have been overcome by virulent isolates of viruses; only 10 % of the sample of resistance genes have proved exceptionally durable. Virulence may involve different viral functions. The production of infectious cDNA clones, and construction of chimaeric recombinants between clones of virulent and avirulent isolates, is now allowing detailed mapping of virulence determinants.

Transformation of plants with ‘novel’ genes for virus resistance, based on coat proteins and viral satellites, may allow construction of more robust resistance systems.
An electrophysiological investigation of the susceptible (cooper) and resistant (kdr; super‐kdr) strains of the adult housefly, Musca domestica L
Authors: Gibson Amanda J. , Osborne Michael P. , Ross Hamish F. , Sawicki Roman M.
Published: November 2006

The electrical activity of abdominal nerves of the housefly, Musca domestica L., was used as a bioassay to study nerve sensitivity to DDT and deltamethrin in susceptible (Cooper) and resistant (kdr, super‐kdr) strains. By this technique the resistant strains were less sensitive (approximately 10 000‐fold) than Cooper, but the bioassay could not distinguish between super‐kdr and kdr in their responses to either compound and so could not account for the greater resistance shown by flies with super‐kdr above kdr flies when these insecticides are applied topically. Although factors other than nerve insensitivity may be involved, the compounds were applied to the preparation in aqueous saline solutions at, or close to, their solubility limits and this could have masked differences in responses of nerves from the resistant strains.
Degradation of carbetamide and its chief metabolites in alkaline soil
Authors: Cantier Jean Michel , Bastide Jean , Yan Zhixing , Coste Camille
Published: November 2006

The degradation kinetics of carbetamide D‐(−)‐N‐ethyl‐2(phenylcarbamoyloxy) propionamide and its potential metabolites have been measured at different temperatures in both unsterilized and sterilized alkaline soil. A very large difference in both rates and processes of degradation between compounds was found. The kinetic studies were conducted by quantitative and qualitative analysis of the transformed product using [14C]‐labelled compounds. Good radioactivity recovery was obtained and the existence of an important non‐extractable fraction was detected in all cases. This soil‐bound fraction is attributed to either conjugation of aniline with soil organic matter or aromatic ring cleavage to give amino acid precursors.
Degradation of ethylenethiourea on lettuces
Authors: Smith Roger M. , Madahar Kirpal C. , Salt W. G. , Smart Nigel A.
Published: November 2006

The rates of uptake and loss of ethylenethiourea (ETU) in lettuces were studied following the application of ethylenethiourea or selected ethylenebisdithiocarbamate fungicides to the soil or to the leaves of potgrown plants. Analyses were carried out using high performance liquid chromatographic analysis of ETU. The amounts of ETU residues on leaves decreased rapidly and were negligible within a week, unless ethylenebisdithiocarbamate fungicides had been applied to the soil, as the latter were degraded simultaneously to give additional ETU which was then taken up by the plants.
The influence of volume rates on the activity of glyphosate and difenzoquat assessed by a parallel‐line assay technique
Authors: Kudsk Per
Published: November 2006

The influence of volume rate and nozzle size on the activity of difenzoquat and glyphosate against outdoor, pot‐grown wild oats and barley plants, respectively, was assessed using a parallel‐line assay technique. The results showed that the assumption of parallel dose‐response curves for difenzoquat and glyphosate was not rejected in either experiment. An inverse relationship between herbicidal activity and volume rate was found with both herbicides, but volume rate had a more pronounced impact on glyphosate activity than on difenzoquat activity. For a given spray volume, no impact of nozzle size on the activity of glyphosate was found. The advantages of applying the parallelline assay in studies of the influence on herbicide activity of factors not supposed to affect the mode of action of the herbicide are discussed.
Inhibition of insect cytochrome P‐450 by some metyrapone analogues and compounds containing a cyclopropylamine moiety and their evaluation as inhibitors of juvenile hormone biosynthesis
Authors: bélai Iván , Matolcsy GyöRgy , Farnsworth Dan E. , Feyereisen René
Published: November 2006

Two metyrapone analogues, 2‐(l‐imidazolyl)‐2‐methyl‐l‐phenyl‐l‐pro‐panone (A‐phenyl‐B‐imidazolyl‐metyrapone; III) and 2‐methyl‐l‐phenyl‐2‐{1,2,4‐triazol‐l‐yl)‐l ‐propanone (A‐phenyl‐B‐triazolyl‐meiyrapone; IV) as well as two cyclopropylamine derivatives. N‐cyclopropyl‐4‐icrt‐butylbenzylamine (V) and N‐cyclopropyl‐4‐(3,7‐dimethyl‐7‐methoxy‐octyloxy)benzamide (cyclopropylamine acylated with a JH analogue acid of known structure; VI) were synthesized and evaluated in biological assays for JH biosynthesis on cockroach, Diploptera punctata corpora allata and egg growth in adult cockroach as well as for mixed function oxidase activities, i.e. epoxidation of aldrin to dieldrin and O‐demethylation of 7‐methoxy‐4‐methylcoumarin to 7‐hydroxy‐4‐methylcoumarin on microsomes from housefly, Musca domestica, abdomen and from cockroach midgut.

Compound VI was a good in‐vitro inhibitor of JH biosynthesis, but it had significantly lower activities in the assays for inhibition of microsomal cytochrome P‐450. Compound IV and metyrapone had moderate activity as inhibitors of oocyte growth. Compounds III, IV and V were more potent inhibitors of housefly aldrin epoxidation than metyrapone and they inhibited the enzyme activity by almost 100% at 02mM, while in cockroach midgut microsome assay metyrapone was more potent than these three compounds.
Deltamethrin raises potassium activity in the microenvironment of the central nervous system of the cockroach: An assessment of the potential role of the blood‐brain barrier in insecticide action
Authors: Hendy Christopher H. , Djamgoz Mustafa B. A.
Published: November 2006

The effect of deltamethrin (10μm) on extracellular K+ activity in the micro‐environment of the central nervous system of the cockroach has been studied. At normal room temperature, deltamethrin induced a rise in the K+ concentration of about 3 mM, representing some 75% increase from normal Deltamethrin also caused a transient surge in the frequency of spontaneous activity, which preceded the K+ effect. At a lowered temperature, the final value of the deltamthrin‐induced rise in extracellular K+ concentration was very similar to normal. However, when the structural component of the blood‐brain barrier was disrupted, the effect of deltamethrin was much reduced. Possible consequences of the deltamethrin‐induced rise in extracellular K+ concentration and the potential role of the blood‐brain barrier in insecticide action are discussed.
Quantitative autoradiography of GABA receptors in locust (Schistocerca americana) brain
Authors: Schouest Leo P. , Miller Thomas A. , Olsen Richard W.
Published: November 2006

Conventional film autoradiography was used at the light microscopic level for the localization and quantization of 4‐aminobutyric acid (GABA) receptors in the locust brain (Schistocerca americana). Localization of the receptor site was achieved via binding with the receptor‐ligand probe [3 H]muscimol. Frozen sections were cut and subsequently incubated either in 40 nM [3H]muscimol or by coincubating sections with [3H]muscimol and one of the following: GABA (50 μM)], a receptor specific agonist [muscimol (1 μM) or isoguvacine (1 μM)], an uptake inhibitor [nipecotic acid (50 μM)], or a noncompetitive channel modulator [avermectin B1a, (1 μM) or aldrin (50 μM)]. Through computer image enhancement and densitometric analysis of the optical density of [3H]muscimol binding sites, the interaction of the above compounds with the putative GABA receptor was determined for various anatomical regions of the locust brain. By comparing the differently treated, but adjacent sections, GABA receptor distribution was quantitated and mapped. Receptor sites were found distributed in the antennal lobes, central body, β‐lobe and β‐lobe of the corpus pedunculatum, protocerebral bridge, and calyx as well as the optic lobe regions.
Pharmacological differentiation of responses to dopamine, octopamine and noradrenaline recorded from a cockroach motoneurone
Authors: Pitman Robert M. , Davis Julian P. L.
Published: November 2006

Recordings have been made from the soma of a cockroach common inhibitory motoneurone. Locally applied dopamine, octopamine or noradrenaline all depolarised the neurone and produced a modest increase in membrane conductance. Under voltage‐clamp, currents evoked by these amines showed considerable voltage dependence. The current‐voltage relationships for dopamine and octopamine responses were similar, but differed from that for noradrenaline. The unusual voltage‐dependent characteristics of these responses suggest that these compounds may serve a modulatory function in the insect CNS.

The effects of a range of pharmacological antagonists indicate that dopamine acts upon a class of receptors distinct from those mediating responses to octopamine, noradrenaline and acetylcholine (ACh). Dopamine currents were abolished by SCH 23390 or cis‐(Z)‐flupenthixol, which did not depress responses to the other agonists. Octopamine and noradrenaline currents were selectively blocked by metoclopramide and ergometrine respectively, while β‐bungarotoxin and gallamine preferentially suppressed ACh responses.

At the present time the ionic basis of dopamine responses is unclear. Dopamine‐evoked currents were totally abolished by application of Cd22+ or verapamil or when the preparation was bathed in Ca2+ free external solutions. Changes in the external concentrations of Na+, K+ or Cl−, however, also had some effect upon dopamine currents.
Impact of two synthetic pyrethroids and methomyl on management of the cabbage aphid, brevicoryne brassicae (L.) and its associated parasitoid, diaeretiella rapae (M'Intosh)
Authors: Abo El‐Ghar Gamal E. S. , M. El ‐Sayed Abd El‐Ghany
Published: November 2006

The effectiveness of two synthetic pyrethroids, cypermethrin and fenvalerate, and of methomyl applied to cabbage plants was tested against the cabbage aphid, Brevicoryne brassicae (L.), and its parasitoid, Diaeretiella rapae (M'Intosh). Dosage rates chosen were equivalent to the manufacturer's maximum and minimum recommendations. Methomyl was considerably more toxic to B. brassicae adults than the two synthetic pyrethroids used. Fenvalerate, at the lowest rate used (71 g ha−1), showed satisfactory effectiveness in reducing aphid adult population on treated plants by c. 77% below that of the control. All insecticides and rates used significantly reduced the emergence of parasitoid adult D. rapae from mummified aphids compared to the control. Fenvalerate clearly had less impact on emergence than cypermethrin or methomyl at any dosage used, while methomyl has appeared to be the most toxic compound in this respect. Longevity of parasitoid adults was highly affected by insecticide application, particularly those adults emerging from mummified aphids exposed to methomyl or cypermethrin. However, only a slight difference in longevity was seen at the lower rate of 71 g ha−1 of fenvalerate. At the lowest dosage rates used, methomyl and cypermethrin reduced the F1‐progeny of adult parasitoid females by 70.5% and 58.3%, respectively, of the control, whereas fenvalerate reduced the progeny by only 36.4%.
Response of the german cockroach Blattella germanica (L.) to a light source following exposure to surface deposits of insecticides
Authors: Miall Stephanie M. , Le Patourel Geoffrey N. J.
Published: November 2006

Adult male German cockroaches were exposed to surface deposits of insecticides for 5 min in the central compartment of a three‐compartment choice chamber illuminated at one end. They were then allowed access to the escape compartments and their distribution recorded over the subsequent 60 min. Cockroaches exposed to pyrethroid insecticides rapidly accumulated in the escape compartment closest to the light source; the same effect was observed to a lesser extent following exposure to propoxur. Boric acid and bendiocarb deposits inhibited the movement of the cockroaches away from the light source, and fenitrothion deposits delayed it. Dieldrin had no effect on the distribution of cockroaches within the choice chamber. The reversal of the normal tendency of German cockroaches to move from a light area to a dark harbourage following exposure to pyrethroids may contribute to the flushing action observed when these chemicals are used for control of B. germanica populations.
Simultaneous determination of benzimidazole fungicides by HPLC on apples, pears and their pulps
Authors: Bicchi Carlo , Belliardo Flavio , Cantamessa Liliana , Gasparini Gianfranco , Icardi Marisa , Sesia Elio
Published: November 2006

The simultaneous HPLC determination of carbendazim, thiabendazole and thiophanate‐methyl in apples, pears and their pulps is described. The method is based on a clean‐up procedure carried out on an Extrelut 20 cartridge followed by HPLC analysis on a Diol column using hexune+isopropanol as mobile phase. Average recoveries of 83.8% for carbendazim, 82.9% for thiabendazole and 68.8% for thiophanate‐methyl on apple matrix were obtained; recoveries on pear matrix were in the same range. Detection limits with UV detection at 285 nm of 100 ng ml−1 for carbendazim, 140 ng ml−1 for thiabendazole and 500 ng ml−1 for thiophanate‐methyl were achieved.
Effects of the experimental fungicide RH 886 on Mucor piriformis
Authors: Spotts Robert A. , Dobson Robin L.
Published: November 2006

No registered fungicide controls Mucor piriformis, a cause of severe postharvest storage rot in pears, but the experimental fungicide RH 886 (active ingredients: 77% 5‐chloro‐2‐methylisothiazol‐3‐(2H)‐one and 23% 2‐methylisothiazol‐3‐(2H)‐one) has an ED50 of 23.1 μg ml−1 in 5 min exposure for germination of sporangiospores of M. piriformis and an ED50 of 9.9 μg ml−1 for mycelial growth. Mixing RH 886 into infested, amended soil at 8 mg g−1 soil or mixing copper sulfate into soil at 1 mg g−1 soil prevented sporulation of M. piriformis. Application of RH 886 to pear fruits prior to inoculation, or immersion of fruits in solutions of RH 886 containing sporangiospores of M. piriformis significantly reduced fruit infection.
Colloidal aspects of pesticidal and pharmaceutical formulations—An overview
Authors: Tadros Th. F.
Published: November 2006

In this overview, the colloidal aspects of pesticidal and pharmaceutical formulations of the dispersion type are described. The nature and magnitude of the interaction forces between particles or droplets in a dispersion are briefly described. These include double‐layer, steric and van der Waals' interactions. Combinations of these interaction energies govern the stability/instability of dispersions. The various states of suspensions and emulsions can be described in terms of energy‐distance curves. Particular attention is given to the various break‐down processes, such as flocculation, coalescence, Ostwald ripening and phase inversion. Some guidelines for the stabilisation of suspensions and emulsions are given. The following practical aspects of dispersion and emulsion formulation are discussed: (a) creaming, sedimentation and their prevention; (b) the assessment of the state and long term physical stability of suspensions, including particle and droplet size analysis and rheology. In the latter case, both steady‐state shear stress–shear rate and low deformation (oscillatory, constant stress and shear wave propagation) are very useful in the control and assessment of the long term physical stability; (c) mixed suspensions and emulsions i.e. suspoemulsions. The possible interactions between suspension particles and emulsion droplets are briefly described; (d) multiple emulsions that can be applied for sustained release; (e) microemulsions, their formation and characterisation illustrating the potential application of these systems in formulations: (f) microencapsulation, describing the most common procedures for preparation of such systems. These include interfacial polymerisation and condensation and coacervation techniques.
Mycoherbicides: Opportunities for genetic manipulation
Authors: Greaves Michael P. , Bailey John A. , Hargreaves John A.
Published: November 2006

Possibilities of using genetic manipulation to improve the effectiveness of mycoherbicides are discussed. Particular emphasis is given to fungal genes involved in the production of specialised structures essential for colonisation and reproduction in pathogenesis and in regulating pathogen specificity. Example are given of relevant genetic transformations in fungi which have already been achieved. In the short term, manipulation of genes encoding for specific enzymes or toxins is considered to be the most promising approach for improving mycoherbicide performance.
The biological activity of acifluorfen‐sodium and its relationship to wetting, penetration and wax composition in four species
Authors: Willingham Gary L. , Graham Linda L. , Westmoreland David G.
Published: November 2006

The biological activity of the sodium salt of acifluorfen was determined for velvetleaf (Abutilon theophrasti), cocklebur (Xanthium pensylvanicum), morning‐glory (Ipomoea sp.), and soybean (Glycine max) in greenhouse tests and by a leaf‐disc efflux assay which bypasses cuticular penetration. The greenhouse activity in order of decreasing control was morning‐glory > cocklebur > velvetleaf > soybean. Activity in the efflux assay in order of decreasing control was velvetleaf ≈︁ morning‐glory > cocklebur > soybean. Leaf wetting was determined by contact angle measurements. Cocklebur wets very readily, and this was attributed partly to its more polar wax content. Soybean wets very poorly, primarily due to its large leaf hairs, which accounts for part of acifluorfen selectivity. Surfactants and inorganic salts increased penetration in a species‐specific manner, and as penetration increased, so did activity. Acifluorfen‐sodium is more active on velvetleaf than on cocklebur in a leaf‐disc efflux assay, but in the greenhouse the reverse is true. This may be explained by the fact that penetration is eight times greater in cocklebur than in velvetleaf.

The chemical composition of the leaf waxes was determined for each species by gas chromatography–mass spectroscopy (GC/MS). Morning‐glory and velvetleaf waxes consist mainly of long‐chain esters. Soybean wax is primarily a C‐30 alcohol. Cocklebur wax is primarily composed of one material which is not a typical leaf wax. This component could not be conclusively identified, but contains several carbonyls, several vinyl groups, and possibly a hydroxyl group. This wax is more polar than the other leaf waxes and seems to account for the extremely good wetting and high degree of penetration in cocklebur compared to the other species. Wax composition does not relate to penetration or activity in the other three species tested. More complex differences in cuticle structure and biological sensitivity probably account for differences in penetration and activity.
Variable resistance factors of fungicides acting as sterol demethylation inhibitors
Authors: Köller Wolfram , Wubben Jos P.
Published: November 2006

The ED50 values and resistance factors of 20 fungicides that all act as inhibitors of the C‐14 demethylation of 24‐methylenedihydrolanosterol were determined for one wild‐type and four resistant strains of Ustilago avenae. All fungicides were cross‐resistant to each other; however, the resistance factors varied considerably, ranging from 50 (triadimenol) to 2·2 (miconazole). A tentative structural requirement for low resistant factors was the presence of two phenyl rings separated from each other by at least three atoms. Labeling of lipids with [14C]acetate in the absence and presence of the inhibitors and subsequent sterol analysis revealed that the variable resistance factors were not related to the presence of a second target site. In spite of reported second modes of action of fenarimol, tebuconazole or miconazole, accumulation of C‐14 sterol precursors in both sensitive and resistant isolates was necessary to accomplish growth inhibition.
The lipid compositions of two isolates of Cladosporium cucumerinum do not explain their differences in sensitivity to fungicides which inhibit sterol biosynthesis
Authors: Carter Geoffrey A. , Kendall Sheila J. , Burden Raymond S. , James Carolyn S. , Clark Terence
Published: November 2006

Isolate 840905 of Cladosporium cucumerinum, when grown on agar or in liqiud medium, was sensitive to triadimenol, HWG 1608 (tebuconazole), fenpropimorph and pimaricin but relatively resistant to terbinafine. Conversely, isolate 49628 was sensitive to terbinafine but relatively resistant to the other fungicides. Changes in sterol composition following treatment with the fungicides reflected the known modes of action of each fungicide. When individual enantiomers of triadimenol were tested against isolate 840905 the order of activity in reducing mycelial growth was 1 S, 2R > 1R, 2R > 1R, 2S ≈︁ 1S, 2S, and this was paralleled by the depletion of ergosterol and the appearance of 14α‐methyl sterols. Isolate 49628 had a greater saturated:unsaturated fatty acid ratio than did isolate 840905 but no major changes in fatty acid composition of either isolate were induced by fungicide treatment. There appears to be no obvious explanation for the differences in fungicide sensitivity of the isolates in terms of their lipid compositions.
The effect of sublethal doses of cypermethrin on Egg laying of mustard beetle (Phaedon cochleariae (F.))
Authors: Hajjar Mohammad J. , Ford John B.
Published: November 2006

Diluted cypermethrin EC was sprayed on to radish plants in the laboratory and its toxicity to mustard beetle was assayed. Doses at or below an equivalent of 3g ha−1 (LD6) were used to measure sublethal effects. A substantial reduction in egg laying occurred even at doses as low as 1 and 1.5 g ha−1. This was due to two factors, the toxicity factor and the antifeeding factor. Insects showing sublethal symptoms of poisoning laid fewer eggs, the reduction being proportional to the dose. On treated leaves, oviposition behaviour was abnormal, eggs being laid on the surface instead of in niches excavated by the female. Feeding was reduced on treated leaves and a positive correlation was demonstrated between the amount of feeding and the proportion of eggs laid in niches. A reduction in hatching occurred when eggs were not laid in niches.

Doses of 3 g ha−1 killed the first instar larvae even seven days after application. The effects on adult feeding and oviposition of a sublethal dose of 3 g ha−1 persisted for a period up to 20 days post‐treatment.
Metabolism of phenyl‐3 H‐indoles by cell suspension of Acer pseudoplatanus L. and their phytotoxicity
Authors: Bastide Jean , Carre Philippe , Gomez Francis , Greiner Alfred
Published: November 2006

Phenyl‐3H‐indoles inhibited growth of Acer pseudoplatanus cells but were not toxic in vivo. Experiments were conducted to find out why the compounds gave a toxic response in cell suspension but not a phytotoxic response in whole plants. The behaviour of two phenyl‐3H‐indoles, (2‐(4‐chlorophenyl)‐3,3‐dimethyl‐5‐fluoro‐3H‐indole and 2‐(4‐chlorophenyl)‐3,3‐dimethyl‐5‐carboxy‐3H‐indole), was investigated in cell suspensions. Absorption and metabolism by cells were rapid. The major metabolite was identified as a polar conjugate of 2‐(3‐hydroxy‐4‐chlorophenyl)‐3,3‐dimethyl‐5‐fluoro‐3H‐indole. This metabolite did not inhibit cell growth. Different phenyl 3H‐indole analogues with the hydroxylation site blocked were synthesised to determine if metabolism was involved in the disappearance of activity in vivo. The results indicated that this was not the case and thus the absence of phytotoxicity must be related to another factor.
Dual effects of dichlorvos on the synaptic transmission in the sixth abdominal ganglion of the cockroach Periplaneta americana
Authors: Lapied Bruno , Vanel Jacques , Hue Bernard
Published: November 2006

The effects of the organophosphate insecticide dichlorvos were studied on the cercal‐afferent giant‐interneurone synapses in the sixth abdominal ganglion of the cockroach Periplaneta americana, using the single‐fibre oil‐gap method. When compared to eserine, dichlorvos showed a dose‐dependent anticholinesterase effect.

Both eserine (10−7 M) and dichlorvos (2 × 10−8 M) increased the amplitude and duration of the composite excitatory postsynaptic potential and acetylcholine potential, an effect corresponding to the well‐known anticholinesterase one. However, during the prolonged action of these compounds, a subsequent decrease of the composite excitatory postsynaptic potential amplitude occurred, whereas the amplitude and duration of the acetylcholine potential continued to increase. The secondary effect (a decrease of composite excitatory postsynaptic potential amplitude) might be attributed to a direct action of the non‐hydrolysed acetylcholine remaining in the synaptic cleft on presynaptic acetylcholine muscarinic receptors, reducing the acetylcholine release by a negative feedback mechanism or to a direct action of dichlorvos on presynaptic and postsynaptic acetylcholine receptors.
Dominant rhizosphere bacteria as a source for antifungal agents
Authors: Lievens Katelijn H. , van Rijsbergen Ronan , Leyns Frederik R. , Lambert Bart J. , Terming Paul , Swings Jean , Joos Henk J.‐P.
Published: November 2006

A search for micro‐organisms associated in high numbers with roots or leaves of corn, grapevine, chicory, soybean, sunflower, barley and sugarbeet yielded a collection of over 10 000 bacterial strains. Within this collection, antifungal strains have been selected, using direct or indirect in‐vitro assays against one target fungus per crop. The target fungi were selected based on their agronomic relevance as pests.

Isolates with antifungal activity were tested for their spectrum of activity against a set of phytopathogenic fungi. In 15 bacterial strains with broad‐spectrum activity, belonging to the species Erwinia herbicola. Serratia plymuthica, Pseudomonas fluorescens, P. aureofaciens, P. cepacia and Bacillus subtilis, the active compounds have been identified. Bacterial strains belonging to the same taxon, but isolated from different ecological niches and/or different places in Europe, produce identical compounds. In two bacterial taxa (Erwinia and Serratia) this was reflected in a genetic conservation of the regions coding for antifungal activity. In both cases, the biosynthetic pathways proved to be genetically complex.

All of the compounds identified in this study have been described previously in bacterial strains isolated from analogous or completely different ecosystems.
Genetically engineered viral insecticides–A progress report 1986 1989
Authors: Bishop David H. L.
Published: November 2006

Among the viruses that are pathogenic for insect species, baculoviruses have been shown to be useful as insecticides for pest control. In some cases they have been used as cost‐effective and environmentally acceptable alternatives to chemical insecticides. However, because viruses need to be ingested and replicate extensively in their host before they kill it, baculovirus insecticides are much slower than chemicals or other reagents that kill insects either on contact or shortly after ingestion. The objective of the programme of genetic engineering of baculovirus insecticides is to improve their speed of action while maintaining their host specificity and other attributes that make them desirable alternatives to chemical pesticides.

Since 1986 four field releases have been undertaken involving genetically engineered baculovirus insecticides. The first release used a genetically marked Autographa californica nuclear polyhedrosis virus (AcNPV). The study began in 1986 and was terminated in 1987. The results demonstrated that an innocuous piece of DNA, appropriately positioned in the AcNPV genome, was an effective means to tag the virus without affecting its phenotype, allowing it to be identified in bioassays of plant and soil samples. The second release, in 1987, involved a genetically marked virus from which the gene coding for the protective polyhedrin protein of the virus had been removed. The field data obtained with this virus showed that it did not persist in the environment, neither in soil, nor on vegetation, nor in the corpses of caterpillars. The third and fourth releases were undertaken in 1988. For one of these studies the marked, polyhedrin‐negative virus was again used. In the other study a polyhedrin‐negative virus that contained a junk' (/?‐galactosidase) gene was employed.
In‐vitro evidence for activative thiolysis and selfsynergism of sulfenyl dicarbamate derivatives of 3,4 methylenedioxyphenyl N‐methylcarbamate
Authors: Wallace Guillermo C. , Zerba Eduardo N.
Published: November 2006

Activative thiolytic cleavage of the N‐S bond and self‐synergism in sulfenyl dicarbamate (SD) derivatives of 3,4‐methylenedioxyphenyl N‐methylcarbamate has been investigated. The formation of precursor carbamates by the reaction of the propoxur derivative with glutathione and cysteine was demonstrated by HPLC.

The slower rate of insectidal action of SD‐propoxur compared with propoxur and its lower ki for inhibition of housefly acetylcholinesterase measured after preincubation of housefly head homogenate with N‐ethylmaleimide were considered as indirect evidence of the N‐S breakdown as a delay factor in toxicity.

The SD‐carbaryl derivative, 3,4‐methylenedioxyphenyl N‐methylcarbamate, and piperonyl butoxide similarly inhibited the oxidative metabolism of [14C]carbaryl in post‐mitochondrial homogenates of housefly abdomens. The results indicated that activative thiolysis and self‐synergism performed by the methylenedioxyphenyl group could be processes involved in the insecticidal action of the sulfenyl dicarbamates.
Structure‐activity‐residue relationships of alkylphenol polyoxyethylene non‐ionic surfactants and MSMA
Authors: Falk Richard H. , Bayer David E. , Hess F. Dan
Published: November 2006

The influence of alkylphenol polyoxyethylene non‐ionic surfactants on the distribution pattern of MSMA (sodium hydrogen methylarsonate) was studied using scanning electron microscopy and X‐ray microanalysis elementmapping techniques. Surfactant concentrations and lipophilic–hydrophilic constitution influenced phytotoxicity and residue patterns. Surprisingly, the percentage of leaf surface covered bore little correlation to phytotoxicity.
Sequential latent effects of a sub‐lethal dose of ivermectin in Calliphora vomitoria L.
Authors: Strong L.
Published: November 2006

A single sub‐lethal dose of 0‐3 μg ivermectin applied topically to third (last) instar larvae of Calliphora vomitoria prevents a significant number of adult flies from escaping from their puparia after metamorphosis, although the flies show no signs of physical abnormality. Of the insects that manage to emerge, a significant number of females do not develop mature oocytes. Ivermectin in sub‐lethal doses seriously impairs post‐embryonic development in Calliphora at four independent levels: interference with pupariation, suppression of adult head development, inhibition of emergence from the puparium, and disruption of ovarian development in the adult female. These findings are discussed in relation to ivermectin's efficacy as a pesticide and particularly to non‐specific effects upon dung‐inhabiting insects.
Characteristics of pyrethroids for insect pest control in agriculture
Authors: Hirano Masachika
Published: November 2006

Pyrethroid insecticides are characterised by high knockdown and lethal activity, a wide spectrum, good residual activity, together with repellent and antifeeding activity. With these characteristics, pyrethroid insecticides have become widely used for plant protection. Their major use has been for the control of bollworms and leafworms in cotton but they have also achieved widespread use for controlling various species of lepidopterous pests in fruits and vegetables, aphids in cereals, and many other minor outlets. Although the early synthetic pyrethroids suffered from a lack of activity against mites and soil pests, later additions, such as fenpropathrin, have combined high acaricidal activity with insecticidal activity and further pyrethroids are being introduced for use in soil.

The extent of pyrethroid use has increased progressively since the first of the ‘photostable’ pyrethroids was registered. In 1986, the market share of pyrethroids reached 25 % of the total insecticide market for plant protection; this figure can be increased in the future.
Pyrethroids and the economics of pest management
Authors: Watkinson Ian A.
Published: November 2006

Pyrethroid insecticides effect excellent control of a wide range of insect pest species at low cost to the user. In outlets where a broad spectrum of pests occur, alternative compounds are often more expensive and frequently have to be combined to provide an acceptable spectrum of control. The benefits of the pyrethroids have led to their extensive and often exclusive use in many of these outlets around the world. However, such dependency on a single class of chemistry brings with it the attendant threat of resistance. Pyrethroid resistance has now been documented in many species of insect around the world and for several of these, changing to other insecticides has meant large increases in the cost of control programs.

Analysis of the US insecticide market has shown that in 1987 the average insecticide cost to a mid‐south cotton grower was $32 acre−1 (1 acre = 0‐405 ha). A hypothetical case was examined where resistance to the pyrethroids occurred in one key pest, Heliothis virescens, the tobacco budworm. The level of resistance was defined such that 50 % of the normally pyrethroid‐treated area was now treated with the most cost‐effective alternative. Under these conditions, a mid‐south grower would see the cost of insect control nearly double to $61‐50 acre.

Extrapolating such increases to the whole US cotton crop or to global cotton production would lead to increased insecticide costs of $230 × 106 and $1‐4 × 109 per year, respectively. Making similar assumptions for all crops, the increased global costs of only a moderate amount of pyrethroid resistance could be as high as $2‐4 × W9 annually. There is, thus, a very real need to maintain the pyrethroids as effective insect‐control agents for as long as possible.
Formulation of insect controlling agents with β‐cyclodextrin
Authors: Szente Lajos , Magisztrak Halina , Szejtli Jozsef
Published: November 2006

Two insecticides, an insect repellent and an insecticide synergist have been complexed with β‐cyclodextrin yielding microcrystalline, wettable, non‐hygroscopic formulations. The insecticides fenitrothion and malathion, the repellent diethyltoluamide and the synergist MGR‐264 were found to form stable inclusion complexes with β‐cyclodextrin.

The molecular encapsulation resulted in improved heat and chemical stability, storability, enhanced wettability and dissolution properties of these rather volatile, poorly water‐soluble agents.
Selection for abamectin resistance in colorado potato beetle (coleoptera: Chrysomelidae)
Authors: Argentine Joseph A. , Clark J. Marshall
Published: November 2006

There was no difference in dose response to abamectin between a laboratory strain of Colorado potato beetle (Leptinotarsa decemlineata (Say))from North Carolina and a multiple resistant strain from Massachusetts (LD50= 1.95 and 1.98 ng larva−1, respectively). Two abamectin‐resistant strains were generated by separate means. The mutagen, ethyl methanesulfonate, was used to generate an abamectin‐resistant strain (LD50= 29.4 ng larva−1) from the susceptible laboratory strain. The other resistant strain (LD50 = 45.3 ng larva−1) was generated through an intense selection with abamectin of a field strain contained in cages set up in existing potato fields. Resistance ratios calculated from LD50values for the two abamectin‐resistant strains were 15‐fold and 23‐fold, respectively. Resistance ratios calculated from LD97values (21‐fold and 38‐fold, respectively) were higher than those calculated at LD50. Also, there were larvae in both resistant strains which were capable of surviving doses up to 100 ng larva−1, while the susceptible strain had no survivors at 10 ng larva−1. Although the logit mortality regression analysis produced statistically different lines for the two abamectin‐resistant strains, the slopes of each appear to be the same. Both resistance factors were determined to be autosomal and incompletely recessive (0.26 to 0.4, respectively) via reciprocal F1crosses to the susceptible laboratory strain.
Residues of the herbicide tri‐allate in preplant and pre‐emergence treated triticale (X triticosecale wittmack) determined by gas chromatography
Authors: Cessna Allan J.
Published: November 2006

Residues of tri‐allate in triticale (X Triticosecale Wittmack) were determined, after both preplant and pre‐emergence soil‐incorporated applications of tri‐allate at 1.4 kg ha−1, at the following crop stages: 2–3‐leaf, 5–6‐leaf, fully headed and mature (straw and grain). Tri‐allate residues were detected only in green tissue samples from the 2–3‐leaf stage of the crop. Recoveries of tri‐allate were in the order of 90 and 85 % from the green tissue and grain at the 100 and 50 μg kg−1fortification levels, respectively.
Effects of pesticides upon nitrogen fixation and nodulation by dry bean
Authors: Schnelle Michael A. , Hensley David L.
Published: November 2006

The effects of seven fungicides, seven herbicides and six insecticides on nitrogen fixation and nodulation by the dry bean (Phaseolus vulgaris L. cv “Bonus”) were investigated. All pesticides examined were found innocuous to nitrogen fixation (acetylene reduction) except bentazone, a post‐emergence herbicide. Bentazone at 3 × label rate (6.7 kg ha−1) consistently depressed nitrogen fixation rates within 48 h after application. However, rates recovered and were comparable to those of control plants after 6 days. No effects were observed on nodulation from any of the pesticides (3 × or label rate) applied.
A new resistance to pyrethroids in tribolium castaneum (herbst)
Authors: Collins Patrick J.
Published: November 2006

The characteristics of a new high‐level, field‐derived resistance to pyrethroids in Tribolium castaneum (Herbst) were investigated using impregnated‐paper and treated‐grain assays.

Piperonyl butoxide almost completely suppressed the resistance, suggesting that the major resistance mechanism was microsomal oxidation. Resistance extended to all pyrethroids tested and to carbaryl but not to organophosphorus insecticides or to methoprene. Resistance was strongest against α—CN phenoxybenzyl cyclopropanecarboxylate pyrethroids and was correlated with structural modifications of the pyrethroid molecule, results also consistent with oxidative resistance.

This resistance will ultimately result in failures to control T. castaneum if pyrethroids, such as deltamethrin, cypermethrin or cyfluthrin, are used in the field, even if they are synergised with piperonyl butoxide. The resistance does not jeopardise organophosphorus materials (e.g. fenitrothion, chlorpyrifos‐methyl, pirimiphos‐methyl, methacrifos) or methoprene.
Effect of diclobutrazol on the growth and sterol and photosynthetic pigment content of winter wheat
Authors: Khalil Iqtidar A. , Mercer E. Lan
Published: November 2006

The effect of the fungicide, diclobutrazol, on the germination, growth, chloroplast pigment and sterol content of winter wheat seedlings has been studied. At 250 μEm it retards their germination and growth, producing smaller, darker green and apparently healthy young plants. This is largely due to the 2S,3S–enantiomeric component. The increased greenness is not due to a direct effect on chloroplast pigments. It inhibits sterol 14—demethylation, causing an increase in the content of 4α,14α–dimethyl sterols, and also increases the proportion of campesterol, a 24—methyl sterol, relative to that of the 24—ethyl sterols, stigmasterol and sitosterol. Both the 2R,3R– and 2S,3S–enantiomers appear to be able to cause these changes in sterol content.
Tracing a 14C‐labeled carbamate molluscicide through the digestive system of deroceras reticulatum (müller)
Authors: Triebskorn Rita , Künast Christoph , Huber Rolf , Brem Gerd
Published: November 2006

The passage of a 14C‐labeled carbamate, 2‐(2‐chloro‐1‐methoxy‐' ethoxy)phenyl N‐methylcarbamate, or its labeled metabolites through the alimentary system of the grey garden slug Deroceras reticulatum was examined by autoradiographic studies and scintillation counting. It was demonstrated that, in a first step, the molluscicide penetrated the cells of the oesophagus and the crop. It was quickly transported by the hemolymph to the periphery of the body and re‐entered the cells of the digestive tract and the mid‐gut gland in a second step from the hemolymph side. The crypt cells of the mid‐gut gland are discussed as cells involved in detoxification, and connective tissue cells as the major storage sites of the labeled material. Excretion in feces and secretion in mucus are thought to be the routes of 14C elimination.
Nematicidal activity of some essential plant oils
Authors: Sangwan Naresh K. , Verma Braham S. , Verma Kailash K. , Dhindsa Kuldip S.
Published: November 2006

Nematicidal activity of the essential oils of different plant species belonging to the families Labiatae (Ocimum basilicum, Ocimum sanctum and Mentha piperata), Myrtaceae (Callistemon lanceolatus and Eugenia caryophyllata) and Gramineae (Cymbopogon caesius) and their major monoterpenoidal constituents, linalool, eugenol, menthol, cineole and geraniol was determined against second‐stage juveniles of seed‐gall nematode (Anguina tritici), citrus nematode (Tylenchulus semipenetrans), root‐knot nematode (Meloidogyne javanica) and pigeon‐pea cyst‐nematode (Heterodera cajani). The essential oil of E. caryophyllata and its major constituent eugenol, as well as linalool and geraniol, exhibited non‐specific activity against all the four nematodes tested.
Cytochemical demonstration of the effects of the acylureas flufenoxuron and diflubenzuron on the incorporation of chitin into insect cuticle
Authors: Lee Susan A. , Clarke Barry S. , Jenner Donald W. , Williamson Francis A.
Published: November 2006

Flufenoxuron (“Cascade”) is a novel acylurea with acaricidal and insecticidal properties. It acts in a similar manner to diflubenzuron (DFB) by impairing chitin incorporation into insect cuticle.

Chitin can be localised cytochemically using the lectin, wheat germ agglutinin (WGA), which binds specifically to N‐acetylglucosamine‐containing polymers. WGA adsorbed to monodisperse colloidal gold (WGA‐gold) was used as an electron‐dense marker for localising chitin in the cuticle of sixth‐instar Spodoptera littoralis.

In the cuticle of control insects, the deposition zone and endocuticle were heavily labelled. In flufenoxuron‐ and DFB‐treated insects, only the endocuticle (formed before treatment) was labelled, the deposition zone being devoid of label.

These results show that flufenoxuron and DFB act in similar manner in reducing chitin incorporation in the cuticle of S. littoralis.