bluuebunny/crossref_metadata_2025 huggingface dataset:
Phenylpyrazoles, a new class of pesticide: Effects on neuromuscular transmission and acetylcholine responses
Authors: Klis Sjaak F. L. , Nijman Nic J. , Vijverberg Henk P. M. , van den Bercken Joep
Published: November 2006

Phenylpyrazoles constitute a newly developed class of chemicals with insecticidal and herbicidal properties. In acute toxicity experiments in rats, near‐lethal doses of phenylpyrazoles produce neurotoxic symptoms with an unknown mode of action. We have investigated the effects of two phenylpyrazoles, SLA4722 and SLA4685, in the frog neuromuscular junction and in the clonal muscle cell line BC3H‐1. In the frog neuromuscular junction SLA4722 at concentrations ⩾ 10−5 M caused a pronounced increase in the frequency of miniature endplate potentials (MEPPs). SLA4685 caused a similar increase but was less potent. In the clonal muscle cell line BC3H‐1, SLA4685 produced a concentration‐dependent block of the acetylcholine (ACh) response (IC50 = 2.4(±0.3) × 10−5 M). At 10−6 M a slight potentiating effect of SLA4685 on the ACh response was observed. SLA4722 was less potent in this preparation. The increased transmitter release might, at least partly, be responsible for the excitatory effects of the phenylpyrazoles in intact animals.
Cuticular penetration of foliar‐applied diflufenican in Galium aparine L.
Authors: Knight Heather , Kirkwood Ralph C.
Published: November 2006

The herbicide diflufenican is an effective pre‐emergence compound used for the control of ‘difficult’ dicotyledonous weeds in winter cereals. It is less efficient when applied post‐emergence, activity being found to depend on the dose reaching the apical meristems. Contact with diflufenican had no significant effect on other parts of the plant and translocation was negligible. In the absence of surfactants, the uptake of diflufenican was minimal and complete approximately 2h after treatment. Surfactant incorporation increased the time over which uptake occurred, efficiency depending on surfactant type and lipophilicity. ‘Silwet L‐77’ (1.0 g litre−1) was the only surfactant tested which caused sufficient damage to the apex to prevent subsequent recovery of the plant. The effect of nonylphenol ethoxylate surfactants at concentrations above the critical micelle concentration (<1.0 g litre−1) appeared to be partly attributable to leaf damage caused by the surfactant, possibly facilitating uptake. Increasing leaf coverage by surfactants did not necessarily improve uptake and activity.
Sorption of ionisable organic compounds by field soils. Part 1: Acids
Authors: Nicholls Peter H. , Evans Avis A.
Published: November 2006

Sorption of different classes of weak organic acids was measured using soils with a range of pH values, taken from long‐term field experiments that had received different amounts of lime. Non‐ionisable compounds were used to demonstrate that the soils of different pH used in the experiments have similar sorptive properties. Values of the sorption coefficients for chloride ion were negative at all pHs except one. Sorption of moderately polar, monobasic, weak acids was weak in acidic soils and very weak in neutral and alkaline soils where they were predominantly dissociated. A lipophilic weak acid was strongly sorbed even at high pH. A model is presented which estimates soil/water distribution coefficients, at any soil pH, from lipophilicity and pKa of the acid and organic matter content of the soil. The model was derived using sorption measured for substituted phenoxyacetic acids. Sorption values calculated using the model were compared with values measured for chlorsulfur on and showed useful agreement. Dibasic acids were strongly sorbed, probably by the mechanism of ligand exchange, if they were chelating agents with potential to form 5‐ or 6‐membered rings with an acceptor atom. Phenylphosphonic acid was strongly sorbed, being a strong monodentate ligand.
Contributions of stomatal infiltration and cuticular penetration to enhancements of foliar uptake by surfactants
Authors: Stevens Peter J. G. , Gaskin Robyn E. , Hong Sung‐Ok , Zabkiewicz Jerzy A.
Published: November 2006

Radiolabelled deoxyglucose (DOG) and glyphosate were used to investigate the effects of certain non‐ionic surfactants on the kinetics of foliar uptake in three species. ‘Silwet L‐77’ (5 g litre−1), an organosilicone surfactant, enabled spray solutions to infiltrate stomata, providing uptake of DOG into Vicia bean (50%), oat (35%) and wheat (20%) within 10 min of application. ‘Silwet Y‐12301’, another organosilicone, also induced stomatal infiltration but to a lesser extent; unlike L‐77, this was attenuated by partial stomatal closure. A third organosilicone, ‘Silwet L‐7607’, and two conventional surfactants, ‘Triton X‐45’ (OP5) and ‘Agral 90’ (NP9), did not induce stomatal infiltration. The effective minimum concentration of L‐77 required to enable infiltration of stomata was 2 g litre−1. The uptake of glyphosate into bean did not differ from that of DOG but the ‘Roundup’ formulation of glyphosate partially antagonised the infiltration provided by L‐77. Addition of surfactants did not increase the rate of cuticular penetration of DOG into bean but total uptake was increased, except by NP9, either via infiltration (L‐77 and Y‐12301) or by extending the period during which penetration occurred (L‐7607 and OP5). The surfactants had a variable effect on rates of penetration of DOG into wheat and oat. In general, foliar uptake followed an exponential timecourse which was largely complete within 6 h and only rarely approached 100% of the applied chemical. The stomatal infiltration provided by L‐77 caused an increase in translocation of DOG in bean.
Effects of thuringiensin on European red mite (Acarina: Tetranychidae) mortality, oviposition rate and feeding
Authors: Royalty Reed N. , Hall Franklin R. , Lucius Beth A.
Published: November 2006

Effects of two formulations of thuringiensin (ABG‐6162A and ABG‐6266) on mortality, oviposition rate, and feeding of European red mite, Panonychus ulmi (Koch) were evaluated. Mite toxicities of the formulations were not significantly different. Immature instars were significantly more susceptible than adults. Low mortality of all instars was recorded after 3 d, indicating slow activity.

The relationship between log (concentration + 1) of ABG‐6162A and ABG‐6266 and P. ulmi oviposition rate was best described by fourth‐order polynomial equations, suggesting that thuringiensin both inhibits and stimulates P. ulmi oviposition. ABG‐6162A affected oviposition at lower concentrations than ABG‐6266.

A quadratic relationship was observed between log (concentration + 1) of thuringiensin and P. ulmi adult female feeding. ABG‐6162A reduced feeding more than ABG‐6266 at concentrations ⩾ 1 mg liter−1. Toxicity to immatures and the sublethal effects described suggest that thuringiensin may control field populations of P. ulmi despite low initial mortality.
Molecular mode of action of annonins
Authors: Londershausen Michael , Leicht Wolfgang , Lieb Folker , Moeschler Heinrich , Weiss Hanns
Published: November 2006

Extracts of ground seeds from Annona squamosa revealed interesting insecticidal properties. By an activity‐monitored fractionation, different acetogenins, called annonins and annonacin, were determined to be the active components. The investigation of ATP‐levels (at the LT50 value) in Plutella xylostella under treatment with annonin I and antimycin A revealed values of 1.45 and 1.35 μmole g−1 fresh weight respectively, whereas insecticides primarily afecting neurotoxic targets, e.g. cyfluthrin (sodium channels; 2.25 μmole g−1 fresh weight) or parathion (acetylcholinesterase; 2.0 μmole g−1 fresh weight) did not influence the ATP‐levels significantly (control; 1.98 μmole g−1 fresh weight). Further studies on the target site of annonins revealed an inhibitory effect on the NADH‐cytochrome c‐reductase and complex I of insect mitochondria with IC50 values of 4–8 nmole mg−1 protein and 0.8 μM respectively for annonin I. Similar results were observed for the inhibition of complex I from bovine heart muscle (IC50: <0.1 μM) or Neurospora crassa cells (IC50: 0.3 μM), whereas coupling sites II or III were not afected. Furthermore, annonins did not reveal any direct inhibition of oxidative phosphorylation or uncoupling efects.
Prospects for the development of a genetically engineered baculovirus insecticide
Authors: Hawtin Rachael E. , King Linda A. , Possee Robert D.
Published: November 2006

Baculoviruses are insect‐specific pathogens which have been employed for the natural control of insect pests for many years. They present an alternative to the use of chemical agents for crop protection. Their restricted host range enables particular pest species to be targeted, and this prevents any loss of beneficial insects from a treated area. However, their large‐scale development as insect control agents has been limited because they take longer to kill the host following infection than rapidly‐acting chemical insecticides. The aim of genetic modification of baculoviruses is to increase their speed of action, while preserving their beneficial characteristics, so creating a fast‐acting, environmentally friendly insecticide. The prospects for achieving this are discussed in this paper, with consideration of scientific progress and the influence of economic and legislative factors.
Quantitative structure—activity relationships of light‐dependent herbicidal 4‐pyridone‐3‐carboxanilide derivatives II. Substituent effects of anilide and pyridone moieties
Authors: Osabe Hirokazu , Morishima Yasuo , Goto Yukihisa , Masamoto Kazuhisa , Nakagawa Yoshiaki , Fujita Toshio
Published: November 2006

The variations in the light‐dependent herbicidal activity against Echinochloa oryzicola of a number of 4‐pyridone‐3‐carboxanilides with various substituents on the anilide and pyridone rings have been examined by use of physicochemical substituent parameters and regression analysis. The effects of substituents of the anilide ring were such that the activity was related parabolically not only with the substituent hydrophobicity (π) but also with the steric bulk parameter (Es) of the bulkier ortho substituent. The effect of substituents at the 1‐position of the pyridone ring was analysed with steric(STERIMOL L and B5) and electronic(γ1) parameters. That of substituents at the 5‐position of the pyridone ring was explained by a parabolic function of a steric (MR) parameter. Analyses of the activity of 105 analogs confirmed that our previous selection of a candidate compound in this series for field trials was indeed appropriate in terms of physicochemical substituent effects.
Residues of the algicide endothal in water, soil and rice, after paddy field applications
Authors: Maini Paolo
Published: November 2006

In order to obtain residue data from the application of the algicide endothal in Italian rice paddy fields, two experiments were carried out using a 50 g kg−1 granular formulation in a small pond and the same granular and two liquid formulations in actual paddy fields of the Italian rice growing area.

Endothal decay in the pond water was very rapid, reaching residue levels of 0·01‐1·02 mg litre−1 in two days and 0·004‐0·01 mg litre−1 at the third day. The muddy soil of the pond was free from measurable endothal residues( <0·02 mg kg−1). In the paddy‐field waters, the endothal decay was slower, with an average half‐life time of 3·3 days, independently of the type of formulation. The actual residues in water after 6 days ranged from 0·3 to 1·3 mg litre−1 according to the initial amount of product applied, and, consequently, to the initial concentration in water.

Rice samples collected at the normal harvest time from the two paddy fields, treated with three different formulations, showed no endothal residue at the minimum detectable level of 0·01 mg kg−1.
Effects of α‐difluoromethylornithine on photosynthetic oxygen evolution, respiration and polyamine concentrations in detached barley leaves
Authors: Coghlan Steven E. , Walters Dale R.
Published: November 2006

Detached barley leaves were treated with the polyamine biosynthesis inhibitor, α‐difluoromethylornithine (DFMO; 1 mM) for either 30 min or 12 h. Exposure to DFMO for 30 min led to a substantial reduction in photosynthesis, expressed either on a unit leaf‐area or unit chlorophyll basis. On the other hand, photosynthesis (expressed on a unit chlorophyll basis) was increased in leaves exposed to DFMO for 12 h, although when expressed on a unit leaf‐area basis, photosynthesis remained unchanged at lower photon flux densities (0‐300 μmol m−2) and was slightly reduced at higher photon flux densities (300‐800 μmol m−2 s−1) s−1). Respiration was unaltered in leaves exposed to DFMO for 30 min or 12 h. Exposure to DFMO for 30 min resulted in significant increases in chlorophyll concentrations, while carotenoid concentrations remained unaltered. However, chlorophyll concentrations were reduced in leaves treated with DFMO for 12 h, although no change in carotenoid concentration was observed. Polyamine concentrations were not significantly affected by exposure of detached barley leaves to DFMO for 24 h.
Isolation and characterisation of two glucosyltransferases from Glycine max associated with bentazone metabolism
Authors: Leah Jon M. , Worrall Timothy L. , Cobb Andrew H.
Published: November 2006

Two glucosyltransferases capable of glucosylating the primary major bentazone metabolite, 6‐hydroxybentazone, have been isolated from tolerant soybean (Glycine max (L.) Fiskerby V) tissue. A soluble flavonol glucosyltransferase, whose primary substrate was kaempferol, was isolated from 3‐week‐old light‐grown tissue. This enzyme had a relative molecular mass of 44 600, a pH optimum of 6·3 and Michaelis constants for kaempferol and 6‐hydroxybentazone of 0·09 and 2·45 mM respectively. A membrane‐bound glucosyltransferase whose primary substrate was the intermediate shikimic acid metabolite, p‐hydroxyphenylpyruvic acid, was also isolated from 7‐day‐old etiolated tissue. This enzyme had a relative molecular mass of 53000 (which could be dissociated to approximately 28000), a pH optimum of 7·5 and Michaelis constants for p‐hydroxyphenylpyruvic acid and 6‐hydroxybentazone of 0·11 and 1·96 mM respectively. These results suggest that 6‐hydroxybentazone, and possibly many other hydroxylated pesticides, may be further detoxified by several glucosyltransferases with overlapping specificity whose primary role involves the storage of endogenous metabolites.
A patch—clamp study of the action of a nitromethylene heterocycle insecticide on cockroach neurones growing in vitro
Authors: Cheung Helen , Clarke Barry S. , Beadle David J.
Published: November 2006

The mode of action of a nitromethylene heterocycle (NMH) insecticide was studied by patch–clamp techniques using cockroach embryonic cultures as an experimental model. Under whole‐cell recordings, this compound elicited inward currents resembling those induced by O‐acetylcholine (ACh). The reversal potentials for both ACh and the NMH were similar, suggesting that the inward currents induced by both were carried by the same species of ion. Pharmacological investigations of NMH‐induced responses revealed that the insecticidal action of this compound is exerted through agonistic action at the nicotinic acetylcholine receptor. Single‐channel studies were also performed to study the interaction of NMH with the nicotinic‐receptor‐coupled ion channel.
Comparison of symptomatic and neurophysiological activities of enantiomers of the insecticide 3‐phenoxybenzyl 1‐(4‐ethoxyphenyl)‐2,2‐dichlorocyclopropane‐1‐carboxylate
Authors: Nishimura Keiichiro , Masutani Hideki , Holan George , Fujita Toshio
Published: November 2006

The insecticidal activities of optical isomers of 3‐phenoxybenzyl 1‐(4‐ethoxyphenyl)‐2,2‐dichlorocyclopropanecarboxylate and related compounds were measured with American cockroaches and their knockdown activities were evaluated with house flies. The activities of the S(−)‐isomer of the dichlorocyclopropanecarboxylate were higher than those of the R(+)‐isomer. The effects of the compounds on the inward membrane currents induced by a stepdepolarizing pulse in crayfish axonal membranes were examined under voltage clamp conditions by the sucrose gap method. The compounds induced a tail current upon step repolarization of the membrane. The tail current decayed to zero in each record, but developed with time after the start of application of the compound until a steady level was reached. The rate of decay of the tail current observed in axonal membranes treated with the S(−)‐isomer was slower than with the R(+)‐isomer. The rates of development of the tail current induced by the two isomers were not very different.
Herbicidal activity of phosphonic and phosphinic acid analogues of glutamic and aspartic acids
Authors: Miliszkiewicz Dorota , Wieczorek Piotr , Lejczak Barbara , Kowalik Ewa , Kafarski Pawel
Published: November 2006

Phosphonic and phosphinic acid analogues of glutamic and aspartic acids were synthesized and screened for herbicidal activity on Lepidium sativum L. Depending on the chemical structure, they exhibited significant or moderate herbicidal activity against L. sativum roots (with some representatives being equipotent with phosphinothricin), while their influence on shoot growth was negligible. Cucumis sativus L. appeared to be more tolerant to these analogues. The origin of this selectivity remains to be determined.
Resistance risk assessment of two insect development inhibitors, diflubenzuron and cyromazine, for control of the housefly Musca domestica L. Part II: Effect of selection pressure in laboratory and field populations
Authors: Keiding Johannes , El‐Khodary Ahmed S. , Jespersen Jürgen B.
Published: November 2006

Laboratory selection with diflubenzuron (DFB) and cyromazine (CYR) was carried out with strains of houseflies collected on Danish farms. The adult flies were multiresistant to organophosphorus, carbamate and pyrethroid insecticides. Susceptibility to the larvicidal effect of DFB or CYR was monitored on Danish farms where fly control with DFB or CYR had been carried out for one to nine years. On these farms the fly population continued during the winter, but at a low level.

Four strains were selected with DFB in seven out of 13–18 laboratory generations. The selections varied from 56% to 94% mortality. The strains showed 1–5 times increase of LC50 and LC95 to DFB. The larvicidal effect of DFB was monitored on five farms where treatment of fly breeding sources in manure (1 g DFB m−2) was carried out regularly for one to nine fly seasons. On none of the farms was any general increase of tolerance to DFB found. Resistance ratios (R/S) compared to the WHO Standard Reference Strain ranged from 0.8 to 2.0 at LC50 and from 1–0 to 2–9 at LC95.

Two strains were selected with CYR in five or six out of 13 laboratory generations. The selections varied from 62 to 97% mortality. The strains showed no increase of LC50 or LC95. The larvicidal effect of CYR was monitored on three farms where housefly breeding places in the animal houses were treated with CYR (0.5 g m−2) for two fly seasons. No reduction of susceptibility to CYR was found and the R/S was 0.7 to 0.9.

The effect of DFB or CYR selection pressure is compared with other investigations and discussed. Moderate to high resistance to DFB or CYR can develop in housefly populations if the selection pressure is strong, especially when used as feed‐through applications on poultry farms where all feed contains DFB or CYR. If the treatment of fly breeding sources is less complete, resistance problems may not develop.
Measurement of acephate and its principal metabolite in leaves by gas‐liquid chromatography
Authors: Allender William J. , Major E. John , Cresswell Geoffrey C.
Published: November 2006

A semi‐micro method is described for monitoring levels of acephate (O, S‐dimethyl acetylphosphoramidothioate) and its principal metabolite, methamidophos (O, S‐dimethyl phosphoramidothioate) in leaf material derived from treated, hydroponically grown gerberas (Gerbera jamesonii H. Bollus, ex Hook. f.) To minimise injury to the living leaf, analyses were performed on 13‐mm diameter discs punched from the interveinal regions of the lamina. The leaf disc samples were then extracted with ethyl acetate. Clean‐up of extracts was accomplished by passing the filtered leaf extracts through glass mini‐columns containing carbon + filter aid (2 + 5 by mass). Acephate and methamidophos were eluted from the column with methanol and measured simultaneously by programmed temperature gas chromatography using a thermionic specific detector.
Studies on the mode of action of diflufenican in selected crop and weed species: Basis of selectivity of pre‐ and early post‐emergence applications
Authors: Haynes Carla , Kirkwood Ralph C.
Published: November 2006

Diflufenican, a pre‐ and early post‐emergence herbicide, was found to be highly active against a wide range of weeds at application rates of 50–250 g ha‐1. Studies on the mode of selectivity with [14C]diflufenican have demonstrated that selectivity between cereal crops and selected weed species is primarily due to differential uptake and indirectly to translocation; ‘depth protection’ appears to be the major reason for selectivity of soil‐applied diflufenican.
Interaction of tetraconazole and its enantiomers with cytochrome P450 from Ustilago maydis
Authors: Carelli Angelina , Farina Gandolfina , Gozzo Franco , Merlini Lucio , Kelly Steven L.
Published: November 2006

Azole antifungal agents are known to inhibit 14α‐demethylation during ergosterol biosynthesis which is mediated by a cytochrome P450. Tetraconazole and its enantiomers have been evaluated for their activity in Ustilago maydis sporidial growth inhibition and for their interaction with microsomal P450 isolated from this pathogenic fungus. The methodology developed for isolation of microsomes exhibiting a P450 peak in reduced carbon monoxide difference spectra required the preparation and gentle lysis of protoplasts. Using this fraction, tetraconazole was observed to bind to U. maydis P450 producing a Type II spectrum indicative of coordination between the triazole N‐4 and the haem Fe3+. Carbon monoxide displacement of azole bound to P450 was monitored and was found to reflect the relative activity of the enantiomers when treating cells. The results imply that the activity of the enantiomers is due to their affinity with the target enzyme and that the orientation of the substituents on the chiral carbon is important in binding to the sterol 14α‐demethylase of this phytopathogen.
Comparative studies on acylurea insect growth regulators and neuroactive insecticides for the control of the armyworm Spodoptera exempta walk
Authors: Fisk Tanya , Wright Denis J.
Published: November 2006

Leaf‐dip bioassays with commercial pesticide formulations were used throughout this study. Third‐instar larvae of Spodoptera littoralis were bioassayed for comparative purposes. The end‐point mortality against the third‐instar larvae (L3) of two Spodoptera exempta populations (Bangor and Gent) and a S. littoralis population (NRI) was found to occur at 72 h and 120 h for neuroactive compounds (carbamate, organophosphate and pyrethroid insecticides) and acylureas respectively. Overall, the acylureas were found to be more toxic (up to 240‐fold at the LC50 level) than the most active of the neuroactive compounds tested, the pyrethroids. This difference was greatest against S. littoralis, which was markedly less sensitive to the latter compounds. The Gent population of S. exempta was also found to be significantly less sensitive (7‐folt at LC50) to the pyrethroid, lambda‐cyhalothrin, than the Bangor strain. Two of the most toxic neuroactive and non‐neuroactive compounds, the pyrethroid, cypermethrin and the acylurea, teflubenzuron were chosen for further studies with S. exempta (Gent) and S. littoralis. Relatively little difference in the toxicity of teflubenzuron was observed against different larval instars (L2, L3 and L4) of S. exempta when compared with cypermethrin. Choice‐chamber‐experiments on feeding behaviour showed that when L3 larvae of either species were exposed to both treated and untreated leaves. teflubenzuron had no significant effect on larval distribution, the percentage of each leaf disc consumed or larval weight gain when compared with untreated controls. In contrast, a marked dose‐dependent repellent response to cypermethrin‐treated leaves was shown by S. littralis after 6 h. together with corresponding reductions in the percentage of the treated leaf consumed and in larval weight gain. Similarly, when L3 S. exempta were exposed only to pesticidetreated leaves, cypermethrin significantly reduced premoult larval weight gain, whereas tefiubenzuron had no premoult effect. However, following exposure of L3 S. exempta and S. littoralis to teflubenzuron for 48 h prior to moulting, L4 which survived the moult showed reduced weight gain compared with controls, the reduction being more pronounced on maize than on artificial diet. This antifeedant effect increased in proportion to the concentration of teflubenzuron originally administered. The effect of exposure time to teflubenzuron was examined by placing L3 S. exempta and S. littoralis on leaves treated with the approximate LC50 or LC95 dose for 6–48 h. The exposure time required to produce appreciable mortality (relative to LC values) within the treated population was found to be 24 h.
Quantitative structure‐activity relationships of light‐dependent herbicidal 4‐pyridone‐3‐carboxanilides III. 3‐D (comparative molecular field) analysis including light‐dependent diphenyl ether herbicides
Authors: Osabe Hirokazu , Morishima Yasuo , Goto Yukihisa , Fujita Toshio
Published: November 2006

Using a set of representative members selected from 4‐pyridone‐3‐carboxanilides and ortho‐chlorinated diphenyl ethers exhibiting light‐dependent herbicidal activity, we examined the three‐dimensional structure‐activity relationships quantitatively. The most stable conformation of each compound, regarded as the ‘active conformation’, was determined by either semi‐empirical or ab initio molecular orbital calculations. With a hypothesis defining a common substructural skeleton between the two different compound series. each molecule was superimposed. We first analysed the structure‐activity relationship using an index for the substructure shape similarity according to the superimposed conformations. After finding the relevance of the hypothesis, we examined the three‐dimensional structure‐activity relationship using the comparative molecular field analysis procedure. The results suggested that the two different series of compounds have a common region of the receptor site. The variations in the light‐dependent herbicidal potency were governed by hydrophobicty and three‐dimensional steric and electronic field parameters of molecules participating in the transport process and the interaction with the receptor site. The result was consistent with that derived from our previous quantitative analysis with the use of free‐energy‐related substituent parameters and the traditional regression procedure for a large number of pyridone‐carboxanilides.
Acaricidal properties of some synthetic unconjugated allenic anilides
Authors: Bolessa Evon A. , Williams Lawrence A. D.
Published: November 2006

Seven unconjugated allenic anilides with the allenic moiety situated at the 3, 4 position were synthesized and evaluated for acaricidal activity against Boophilus microplus (Canestrinii). The order of toxicity (% adult mortality) of the anilides against adult B. microplus at 0.5 μg tick−1 was: N‐(3‐chloro‐4‐methyl‐phenyl)‐5‐methylhexa‐3, 4‐dienamide, (I) = N‐(4‐bromophenyl)‐5‐methylhexa‐3, 4‐dienamide(III)(100%) > N‐(4‐bromophenyl)‐deca‐3, 4‐dienamide (VI)(68%) > N‐(3, 4‐dichlorophenyl)‐5‐methylhexa‐3, 4‐dienamide (II) (32.3%) > N‐(3, 4‐dichlorophenyl)‐5‐methylhepta‐3, 4‐dienamide (IV) (28%) > N‐(3‐chloro‐4‐methylphenyl)‐5‐ethylhepta‐3, 4‐dienamide (VII) (24%) > N‐(4‐bromophenyl)‐5‐methylhepta‐3, 4‐dienamide (V) (20%).

Comparison of the relative potencies (in parenthesis) at 1.5 μg tick−1 of the anilides with three commercial acaricides: pyrenone, lindane and carbaryl, revealed the following orders of activities: in comparison with pyrenone: pyrenone = I = II (1) > VI(0.93) > II (0.67) > IV (0.55) > VII (0.46) > VI (0.37); in comparison with lindane: I = HI (6.06) > VI (5.65) > II (4.04) > IV (3.36) > VII (2.76) > V (2.39) > lindane (1.0). All anilides were more toxic than carbaryl which gave no mortality at 1.5 μg tick−1.

The need for developing more effective control agents for B. microplus is highlighted by the high levels of resistance found in some Jamaican populations of the pest. Resistance of the orders of 31‐ to 227‐fold had been reported against lindane and between 15‐ and 67‐fold to carbaryl.
Quantitative structure‐activity study of insecticidal 2‐methoxy‐5‐(substituted‐phenyl)‐1, 3, 2‐oxazaphospholidine 2‐sulfides against Musca domestica L. by topical application
Authors: Hirashima Akinori , Yoshii Yutaka , Takeya Ryuko , Eto Morifusa
Published: November 2006

The quantitative relationship between the structure of 2‐methoxy‐5‐(substituted‐phenyl)‐1, 3, 2‐oxazaphospholidine 2‐sulfides (5‐PMOS) and their insecticidal activity against the house fly. Musca domestica L., was analyzed using reported physicochemical parameters and regression analysis. The electronic nature of the substituent on the phenyl group of 5‐PMOS has the most significant effect on the activity, followed by hydrophobic and steric effects; the optimum value of Σρ is zero and the more hydrophobic the substituents on the phenyl group, the higher the insecticidal activity. The plots of observed pLD50, values against calculated pLD50 values for compounds having substituents in the ortho‐position deviated downwards from those of compounds having substituents at the meta and/or para positions. This ortho‐effect, which reduces the insecticidal activity of compounds having substituents at the ortho‐position, was expressed by a dummy parameter D, which has the value 2 for di‐ortho‐substituted derivatives, 1 for mono‐ortho‐substituted derivatives and zero for others. Thus, the highest activity was obtained for 2‐methoxy‐5‐phenyl‐1, 3, 2‐oxazaphospholidine 2‐sulfide, and the activity was decreased by the introduction of any substituents on the phenyl group.
Correlation of protoporphyrinogen oxidase inhibition by O‐phenyl pyrrolidino‐ and piperidino‐carbamates with their herbicidal effects
Authors: Nandihalli Ujjana B. , Sherman Timothy D. , Duke Mary V. , Fisher James D. , Musco Vincent A. , Becerril José M. , Duke Stephen O.
Published: November 2006

Phenopylate

Phenopylate is not a BSI/ISO‐approved common name.

(2, 4‐dichlorophenyl 1‐pyrrolidinecarboxylate) and 13 of its O‐phenyl pyrrolidino‐ and piperidino‐carbamate analogues were tested for their capacity to inhibit protoporphyrinogen oxidase (Protox), to cause accumulation of protoporphyrin IX (Proto IX), and to cause herbicidal injury. All 14 compounds inhibited Protox of barley etioplast preparations. The I50 values ranged from 21 nM to 4 mM. Highly significant correlations were found between Protox I50 values and herbicidal activity of the more active of the compounds on greenhouse‐grown weeds (pitted morningglory, barnyardgrass, prickly sida, and velvetleaf), pre‐ and/or post‐emergence, and on cucumber cotyledon discs or barley leaf sections in cellular leakage bioassays. Proto IX accumulation in barley leaf sections treated with any of the 14 compounds correlated well with both the I50 values for Protox inhibition and with herbicidal damage to the tissue sections. These data indicate most or all of the herbicidal damage caused by these compounds is due to inhibition of Protox.
Time, concentration and temperature relationships for phosphine activity in tests on diapausing larvae of Ephestia elutella (Hübner) (Lepidoptera: Pyralidae)
Authors: Bell Christopher H.
Published: November 2006

The activity of phosphine against diapausing larvae of Ephestia elutella was shown to depend on several different interactions of duration of exposure, temperature and gas concentration. Using the model proposed by Knight, (CC0) × (tt0) = k, a constant for mortality, the minimum effective concentration C0 was raised and the minimum effective exposure t0 extended as temperatures were increased. The effect of temperature on these thresholds was reduced at higher mortality levels. A range of concentration levels, influenced by temperature, elicited an increase in tolerance at the LD99 level over that evident at higher or lower concentrations. These concentration ranges were 0.9–2‐1 mg litre‐1at 25°C,0.7–2.3 mg litre‐1 at 20°C and 0.1–1.5 mg litre‐1 at 15°C.

A mathematical model was fitted to relate concentration and time thresholds, mortality and temperature. At the LD50 level, values for t0 ranged from 2.5 h at 15°C to 5.0 h at 25°C. C0 values increased from about 0.6 to 7.0 μg litre‐1 over this temperature range. At the LD99 level, t0 values ranged from 21 to 28 h and C0 values from 11 to 19 μg litre‐1. Phosphine appeared most effective at each temperature at concentrations from about 40 to 60–100 μg litre‐1.
Determination of chlormequat residues in cotton seed by gas chromatography
Authors: Allender William J.
Published: November 2006

A simple and sensitive method to determine chlormequat (chlorocholine chloride) residues in plant tissue has been devised. The technique is based on an in‐vitro multi‐step reaction where chlormequat is initially N‐demethylated with potassium pentafluorothiophenolate followed by a further reaction with excess reagent to produce a pentafluorothiophenyl derivative. Electron capture detection and mass spectrometry were used for quantitative determination and identification. The method was applied to the analysis of cotton seed harvested from cotton plants treated with various concentrations of chlormequat.
Response of Spodoptera exempta (Walk.) larvae to simulated field spray applications of acylurea insect growth regulators with observations on cuticular uptake of acylureas
Authors: Fisk Tanya , Wright Denis J.
Published: November 2006

The acylurea insect growth regulators flufenoxuron (‘Cascade®’) and teflubenzuron (‘Nomolt®’) were applied to maize plants and/or larvae of the armyworm, Spodoptera exempta (Walk.) at volumes equivalent to medium volume (MV; 250 litre ha−1) and ultra‐low volume (ULV; < 1.0 litre ha−1, VMD = 50 μm) sprays at rates ( ≪ 10 g a.i. ha−1) at or below currently recommended field rates. The Egyptian cotton leafworm, S. littoralis was examined for comparative purposes on Chinese cabbage. One‐day‐old third‐instar larvae (L3) of S. exempta sprayed (MV) with either compound (1 and 10 g ha−1), and confined on similarly treated maize leaves for 48 h, showed a high level of response after 48 h (87–100% effective mortality), with 100% mortality after 120 h. Exposure of sprayed L3 to treated plants for 6 h was only slightly less effective. When only larvae were sprayed, the higher rate for both compounds gave 97% mortality after 120 h. The response rate of one‐day‐old L3 S. littoralis was generally slower but was similar to that of S. exempta after 120 h. When plants and larvae were sprayed at relatively low densities (22–45 drops cm−2) with undiluted ULV formulations, L3 S. exempta showed a greater response to flufenoxuron (50 g litre−1) than to teflubenzuron (25 g litre−1) at 48 h but all larvae were effectively dead (93–100% actual mortality) after 120 h. Similar results were obtained with L5 S. exempta. When only larvae were sprayed (23–25 drops cm−2), equivalent concentrations (25 g a.i. litre−1) of diluted flufenoxuron and cypermethrin ULV formulations gave 87 and 90% mortality respectively with L3 S. exempta after 120 h, although the latter compound acted more rapidly. The diluted flufenoxuron was more toxic than its undiluted formulation at similar spray densities. L3 and L5 S. exempta and L3 S. littoralis showed a similar level of response to undiluted flufenoxuron and teflubenzuron. Little or no difference in toxicity was found for topically applied flufenoxuron and teflubenzuron against L3 S. exempta and S. littoralis. Accumulation of [14C]flufenoxuron appeared to increase progressively over 6 h in both species, while that of [14C]teflubenzuron reached a peak after 1 h. After 6 h, there were relatively greater amounts ( > 2‐fold) of radioactivity in flufenoxuron‐treated than in teflubenzuron‐treated larvae. Such differences may account for the greater speed of action observed with the former compound in some experiments. The potential of flufenoxuron and teflubenzuron for the control of S. exempta is discussed with particular regard to the significant contact activity and reasonably rapid response time (effective mortality at 48 h) shown by these compounds at field rates.
Speed of action and toxicity of acylurea insect growth regulators against Spodoptera exempta (Walk.) and Spodoptera littoralis (Boisd.) larvae: Effect of inter‐moult age
Authors: Fisk Tanya , Wright Denis J.
Published: November 2006

Ultra‐low volume (ULV) spray bioassays at droplet densities (20–80 drops cm−2) corresponding to field deposits were used to determine the efficacy of two acylurea insect growth regulators, teflubenzuron (‘Nomolt®’) and flufenoxuron (‘Cascade®’) against three different age groups of third‐instar Spodoptera exempta and Spodoptera littoralis larvae. While no response (mortality and/or abnormal moulting with impaired ability to feed) was observed with one‐day‐old larvae until 48 h after treatment, two‐day‐old larvae showed some response (27–93% abnormal moulting and 3–10% mortality when larvae were sprayed; 80–100% abnormal moulting and up to 83% mortality when larvae and plants were sprayed) after 24 h and up to 100% mortality at 120 h. Studies with non‐feeding, pre‐moult larvae showed that cuticular uptake of acylureas was sufficient to affect an appreciable proportion of larvae after 24 h, with up to 100% mortality at 120 h. More detailed studies with pre‐moult S. littoralis larvae showed that, while a few larvae which moulted between 1 and 5 h after treatment showed abnormal moulting to the L4 stage, a much larger proportion of larvae which moulted 6–20 h after treatment were affected. Previous studies with S. exempta have shown that different larval instars show similar levels of sensitivity to acylureas. The present work suggests that, while the age distribution within instars has little influence on the end‐point mortality of acylureas, it can profoundly modify the speed of response, the majority of larvae within an instar being effectively controlled at the moult following treatment. The significance of these observations in relation to the crop protection activity of acylureas against field populations of Spodoptera larvae is discussed.
Novel inhibitors of sterol C‐14 demethylase and Δ14 Reductase/Δ8 → Δ7 isomerase for cereal disease control
Authors: Masner Petr , Steel Christopher C. , Furter Rolf , Isenring Hans Peter , Oesterhelt Gottfried , Ziegler Hugo , Zobrist Peter
Published: November 2006

The activity of five experimental fungicides combining structural elements responsible for sterol C‐14 demethylase inhibition and sterol nuclear double‐bond transformations has been investigated by examining sterol accumulation in Ustilago maydis (DC.) Corda, inhibition of sterol‐biosynthesis enzymes in Saccharomyces cerevisiae Meyer using a cell‐free system and protective activity in cereals against Erysiphe graminis DC. and Puccinia coronata Corda. Combining the fenpropidin/fenpropimorph basic structure with a pyridine moiety offered no advantage in fungicidal activity. However, the combination of the pyrifenox structure with a morpholine moiety yielded a compound which was a good inhibitor of C‐14 demethylase and Δ8 → Δ7 isomerase in vitro and gave good cereal protection.
Comparative evaluation of some chitin synthesis inhibitors as insecticides against Colorado beetle Leptinotarsa decemlineata Say
Authors: Malinowski Henryk , Pawinsk Maria
Published: November 2006

The bioactivity of the chitin synthesis inhibitors, chlorfluazuron, hexa‐flumuron, teflubenzuron, triflumuron and GR 572(novaluron) used in commercial or experimental formulations against larvae of Colorado beetle, Leplinotarsa decemlineata Say in laboratory and field experiments was evaluated during 1985–90. All compounds showed high potential for control of the pest. The activity mainly depended on the period of time after treatment. Higher activity was found on younger larvae. A shailow dose‐response relationship was observed for a given larval stage, particularly at the last observation, 15 days after treatment. A single treatment is able to suppress the pest population density below a dangerous level during the whole season. Observations showed that long‐term activity resulted from stomach and contact larvicidal action, reduced egg viability and antifeedant effect.
Weed control and herbicide residues in onion following use of chlorpropham and cyanazine
Authors: Cessna Allan , Benoit Diane Lyse
Published: November 2006

A gas chromatographic method, using nitrogen‐phosphorus alkali flame ionization detection, is presented for the determination of residues of chlor‐propham and cyanazine in onion (Allium cepa L.). Recoveries of chlorpropham and cyanazine were 94 (±16)% and 84 (±7)% at the 100μg kg‐1 fortification level, and 97 (±8)% and 88 (±10)%, respectively, at 50μg kg‐1. Analysis of immature (whole plants) and mature (bulbs only) onions grown at four sites following a pre‐emergence application of chlorpropham at 6.0–6.7 kg ha‐1 and a subsequent post‐emergence application of a tank mixture of chlorpropham plus cyanazine at 4.5 and 1.1 kg ha‐1, respectively, resulted in no detectable residues of either herbicide. Weed control efficacy was evaluated for two consecutive years. The treatment demonstrated 88 % and 70 % broad‐leaved weed control 13 and 27 days after application, respectively, at the one site in Quebec.
In‐vitro biological models
Authors: Cotterrell David
Published: November 2006

Recent developments in the investigation of membrane flux and partition in in‐vitro membrane systems from human and animal tissues are reviewed with an emphasis on three models: multicellular layers, single isolated cells and sub‐cellular membrane fractions. Mechanisms of permeation through multicellular layers such as epithelia. endothelia and confluent layers of cultured cells by radio‐tracer and electrophysiological techniques are considered. For single cells, erythrocytes form one of the major models, and their use, along with reseated ghosts and membrane vesicles, is considered, particularly with regard to the restoration of physiological levels of membrane permeability in the latter. The use of fluorescent intracellular dyes to measure partition into single identified cells dissociated from tissues is discussed. Methods of measuring flux and partition into subcellular fractions from plasma and organelle membranes are reviewed, in addition to new methods of patch clamping small areas of membrane to investigate permeation through single ion channels.
Residues of Mecoprop in Post‐emergence‐Treated Wheat and Oat
Authors: Cessna Allan J.
Published: November 2006

The dissipation of mecoprop in wheat (Triticum aestivum L.) and oat (Avena sativa L.) was monitored over a growing season following post‐emergence application of the dimethylamine salt of mecoprop to each crop at 1·1 kg ha−1. Residues of mecoprop, as its methyl ester, were determined gas chromatographically using electrolytic conductivity detection. Initial residues in wheat (119 (±20) mg kg−1) and oat (95·3 (± 10·0) mg kg−1) on the day of application (four‐leaf stage of wheat and four‐ to five‐leaf stage of oat) decreased to 0·1 to 0·2 mg kg−1, respectively, within six weeks. Residues were non‐detectable in the mature seed of both crops. Recoveries of mecoprop were in the order of 90% from the green tissue and seed of both crops fortified at 0·05 mg kg−1.
Insecticide resistance in Musca domestica L. from Eastern England
Authors: Chapman Paul A. , Morgan Colin P.
Published: November 2006

Strains of houseflies were obtained from a refuse tip and 34 farms selected at random from Eastern England in 1984. Resistance was assessed to four insecticides that had been in use for fly control in the UK. Dose‐response data were obtained by topical application of the insecticides and, in addition, a resistance test method was used in which flies were allowed to feed on sugar coated with either methomyl or azamethiphos. For both methods, the knock‐down (KD) after 48 h was used as a measure of response. The ranges of resistance factors for the topical application method were, for methomyl, 1·1–15·9 at KD50 and 2·1–17·0 at KD95; for azamethiphos, 2·2–36·9 at KD50 and 4·5–88·2 at KD95; for pyrethrins + piperonyl butoxide, 0·9–6·8 at KD50 and 1·4–13·4 at KD95; and for permethrin, 1·7–34·8 at KD50 and 2·2–112·5 at KD95. The ranges of the resistance factors for the feeding tests were, for methomyl, 2·1–39·8 at KD50 and 2·4–64·0 at KD95, and, for azamethiphos, 5·6–51·7 at KD50 and 8·8–92·0 at KD95.
Effect of a Mixture of Chlorpyrifos and Lindane on the Symbiosis of Bradyrhizobium japonicum and Soybean (Glycine max. (L.) Merril)
Authors: Revellin Cécile , De Canson Bruno , Catroux Gérard
Published: November 2006

A mixture of chlorpyrifos and lindane effective for the control of the seed corn maggot (Hylemya platura) was assessed for possible side‐effects on the Bradyrhizobium japonicum–soybean symbiosis. The mixture did not show any detrimental effect on B. japonicum survival in liquid inoculant for 24 hours at concentrations up to 96 mg litre−1 chlorpyrifos and 38·4 mg litre−1 lindane. In greenhouse conditions, early nodulation was not impaired at soil concentrations of 6 mg kg−1 of chlorpyrifos and 2·4 mg kg−1 of lindane. Nodulations and yields were not affected in five field experiments, at 1 and 2 times the normal rate of commercial formulations. Practically, it can be concluded that the mixture is innocuous with respect to its effect on the B. japonicum–soybean symbiosis.
Biochemical Mechanisms Involved in Selective Fungitoxicity of Two Sterol 14α‐Demethylation Inhibitors, Prochloraz and Quinconazole: Accumulation and Metabolism Studies
Authors: Kapteyn Johan C. , Pillmoor John B. , De Waard Maarten A.
Published: November 2006

The selective fungitoxic actions of prochloraz (an imidazole) and a triazole fungicide, quinconazole (3‐(2,4‐dichlorophenyl)‐2‐(1 H‐ 1,2,4‐triazol‐1‐yl)‐ 4(3H)‐quinazolinone: II), were studied with selected phytopathogenic fungi. With the exception of Ustilago maydis, all the fungi tested were more sensitive to prochloraz than to II. A number of DMI‐resistant mutants of Penicillium digitatum and P. italicum showed positive cross‐resistance to both DMIs, but except for P. italicum isolate H17, the levels of resistance to II were much higher than to prochloraz.

The generally higher toxicity of prochloraz to the fungi investigated, as compared to II, could not be ascribed to the slightly higher accumulation of prochloraz. With regard to prochloraz, there was no general correlation between the sensitivity of the fungi tested and the amount of fungicide accumulated. A similar situation was evident for II. However, the DMI‐resistant mutants of P. italicum did show a reduced accumulation of both azoles, which may account for a low level of acquired DMI‐resistance in this fungus. Since accumulation levels of the test compounds in the isolates with different degrees of resistance were the same, additional mechanisms of resistance may be involved in isolates with relatively high degrees of DMI‐resistance.

No detectable amounts of fungicide metabolites were found in most fungi tested over a 16‐hour incubation period. Therefore, fungal metabolism is not generally responsible for the differences in sensitivity between fungi to each azole tested. It also does not generally explain the differential toxicities of prochloraz and II to each individual species. The exception to this was Rhizoctonia solani which metabolized prochloraz to a non‐fungitoxic compound. This correlated with its low prochloraz sensitivity.