bluuebunny/crossref_metadata_2025 huggingface dataset:
Photostabilization of bioresmethrin by organic cations on a clay surface
Authors: Margulies Leon , Cohen Ephraim , Rozen Harel
Published: November 2006

Photostabilization of the pyrethroid insecticide bioresmethrin (BR) was achieved by adsorbing it onto the ciay montmorillonite with a cationic organic chromophore. Experiments in the dark showed that adsorption of BR to the surface of the clay did not inhibit its insecticidal activity. Complexes containing the organic cations methyl green (MG) or naphthylammonium (NA) retained their insecticidal activity against the flour beetle, Tribolium castaneum for 3‐5 days in sunlight whereas unprotected BR was inactivated within a few hours. Optimum stabilization was achieved by definite amounts of BR and MG adsorbed, indicating that photostabilization was due to specific intermolecular interactions on the clay surface rather than to a UV‐screening effect. The interactions between BR and MG at the clay surface were studied by Fourier transform infra‐red spectroscopy.
Excretion and residues of the pyrethroid insecticide cypermethrin in laying hens
Authors: Hutson David H. , Stoydin George
Published: November 2006

Laying hens were treated daily for 14 days with oral doses of [14C‐phenoxy]cypermethrin (1.52 mg day−1, 0‐7 mg kg−1) formulated on a small quantity of diet. Radioactivity in the eggs reached a plateau value of 0.05 μg equivalents g−1 8 days after the start of dosing. Most of the residue was found in the yolk and was a mixture of cypermethrin and material which was closely associated with neutral lipids and phosphatidyl cholines. Four and a half hours after the last dose, the birds were killed and selected tissues were taken for analysis. The highest residue was found in the liver. This was composed of cypermethrin and a mixture of very polar metabolites which were not hydrolysed to significant amounts of 3‐phenoxybenzoic acid or its 4‐hydroxy derivative.
Analytical method for the simultaneous determination of diquat and paraquat residues in potatoes by high‐pressure liquid chromatography
Authors: Worobey Brian L.
Published: November 2006

A novel method was developed for the simultaneous determination of diquat and paraquat residues in potatoes. Potato tissues were spiked at several levels and extracted with acid using a micro‐reflux procedure with 5 g of sample; this was followed by adjusting the hydrolyzate pH to 9 to 10 and using a silica Sep‐Pak for rapid clean‐up and preconcentration. Aliquots of the final eluate were taken to dryness, dissolved in the h.p.l.c. mobile phase and analyzed as their heptanesulfonate ion‐pairs by u.v.‐h.p.l.c. (reverse phase column chromatography) at 254 and 313 nm for paraquat and diquat, respectively. A detection limit of approximately 0.05 mg kg−1 dication in a 5‐g sample of spiked potato (i.e. 0.25 μg ml−1 final extract) was achieved. Recoveries of 79.5 to 97.6% were obtained at spiking levels of 0.05 to 5.0 mg kg−1 for diquat and paraquat with coefficients of variation not greater than 8.27%. The method was developed and validated using 14C‐radiolabelled diquat and paraquat; u.v.‐h.p.l.c. recoveries were comparable with recoveries determined by radioassay. Several parameters affecting the extraction, adsorption and chromatography of diquat and paraquat were evaluated. The formula weights of diquat and paraquat were determined and their importance described; they were determined as mono‐ and tetra‐hydrates, respectively.
Studies into the action of the diphenyl ether herbicides acifluorfen and oxyfluorfen. Part I: Activation by light and oxygen in leaf tissue
Authors: Gillham David J. , Dodge Alan D.
Published: November 2006

The effect of acifluorfen and oxyfluorfen on chlorophyll bleaching, lipid peroxidation and photosynthesis in pea leaf discs was studied. Both her‐ bicides induced light‐dependent bleaching and lipid peroxidation, the level of damage being greater at higher light intensities. Photosynthetic carbon dioxide fixation was only partially inhibited in treated leaf discs incubated in darkness, thus indicating that these herbicides did not inhibit photo‐ synthesis as a primary mode of action. Leaf discs maintained in darkness showed no visible signs of injury, and light‐dependent herbicide‐induced damage was reduced by incubating discs under nitrogen, orpre‐incubating them with the electron‐transport inhibitor monuron. It is suggested that acifluorfen and oxyfluorfen are activated by a light‐dependent process, which requires photosynthetic electron transport.
The determination of the herbicide dinoseb in lentils
Authors: Cessna Allan J.
Published: November 2006

Residues of the herbicide dinoseb were determined gas chromatographically in lentils which had been treated at two locations in Saskatchewan with post‐emergence applications of dinoseb at 1.4 and 1.7 kg ha−1. Herbicide residues, determined at selected times after application, were not detected at the limit of detection of the analytical method (0.05 mg kg−1) in either the seed and straw at maturity, or in the green foliage six to eight weeks after application. Recoveries of dinoseb were 76% from fortified green foliage at the 0.1 mg kg−1 level, and 64% from fortified seed at the 0.05 mg kg−1 level.
The effect of grain moisture on the biological activity of fenitrothion residues on maize in storage
Authors: Samson Peter R. , Bengston Mervyn , Parker Russell J. , Keating Julie A.
Published: November 2006

The biological activity of freshly‐applied fenitrothion on maize at a range of moisture contents was measured using adults of several species of Coleoptera. Activity declined by about ×15 as grain moisture increased from 10 to 24%, the greatest change occurring at moisture contents above about 14%. This occurred regardless of whether the grain was treated with fenitrothion when already moist or was moistened after treatment, and it was not reversed by drying the treated grain. These differences in activity could not be explained by differences in the chemical residues. The suggested mechanism is a reduction in the availability of fenitrothion for pick‐up by insects.
sublethal neurotoxic effects of the fungicide benomyl on earthworms (Eisenia fetida)
Authors: Drewes Charles D. , Zoran Mark J. , Callahan Clarence A.
Published: November 2006

Earthworms Eisenia fetida were treated by surface contact exposure for 4 days with the fungicide benomyl. Non‐invasive electrophysiological recordings after treatment with sublethal concentrations of 0.2‐25 mg benomyl litre−1 of water (=0.003−0.435 μg benomyl cm−2 of filter paper) indicated concentration‐dependent decreases in conduction velocity for the medial and lateral giant nerve fibres. Threshold concentration for these effects was approximately two orders of magnitude less than the LC50. The effects on velocity were not accompanied by alterations in refractory period or impairment of locomotory reflexes, but persisted for at least several weeks after treatment. Morphometric analysis of treated animals revealed a disruption of the myelin‐like sheath surrounding giant fibres but no change in fibre diameters.

It is concluded that benomyl had subtle and sublethal neurotoxic effects on earthworm giant nerve fibres. The data indicate that giant fibre conduction velocity is a particularly sensitive parameter for detecting these effects in intact worms.
Fate of a water‐soluble herbicide spray on foliage: Part I. Spray efficiency: Measurement of initial deposition and absorption
Authors: Don Wauchope R. , Streeth Joe E.
Published: November 2006

MSMA (monosodium methylarsonate) is non‐volatile and degrades in the environment to arsenic species which can be determined at the nanogram level. It is thus an excellent tracer for the study of the efficiency of deposition (defined as the fraction of material sprayed that deposits on target foliage) and subsequent fate of a water‐soluble pesticide applied to foliage. MSMA was applied to rice (Oryza sativa L. cv. Labelle) foliage at two rates and at various stages of growth. After spraying the foliage was sampled and analysed for surface (removable by water‐washing) and absorbed MSMA. Absorption of MSMA was so rapid that within the two hours between application and washing nearly one‐half of the recovered MSMA became unavailable for wash‐off. The total amounts of MSMA recovered were approximately proportional to plant size and application rate. When the rice foliage reached approximately 80 cm in height, the canopy closure (ground cover) was complete; nevertheless, only about 50% of the sprayed MSMA was found on and in the plants. As the rice canopy approached maturity, or approximately 130 cm high, complete interception of the spray occurred. These results indicate that canopy volume rather than ground cover was more important in determining the efficiency of spray deposition in this case, and that deposition efficiency may approach 100% with non‐volatile active ingredients.
Fate of a water‐soluble herbicide spray on foliage. Part Ii. Absorption and dissipation of foliar msma deposits: Mathematical modelling
Authors: Don Wauchope R. , Street Joe E.
Published: November 2006

MSMA (monosodium methylarsonate) was applied to rice (Oryza sativa L. cv. ‘Labelle’) plants at weekly intervals from the time the plants were 46 cm high until heading. Each application was to a different set of plants. The sprayed plant tops were analysed for MSMA immediately after spraying and at weekly intervals thereafter until heading. MSMA deposits became completely absorbed after one week and then the total residues declined exponentially to background levels with a half‐life of about 15 days. Plant stunting effects depended on the amount of MSMA applied and the rate of growth at the time of application. Sterilisation effects depended on the amount of MSMA applied and the proximity in time of the application to panicle initiation. A mathematical model of the data showed that sterility symptoms were consistent with calculated MSMA concentration in tissue at the time of panicle initiation.
Synergistic effects of agonists and antagonists in insect venoms—a natural way of insecticidal action
Authors: Piek Tom
Published: November 2006

Contrary to the typical killing action of most animal venoms, including social wasp venoms, the solitary wasp venoms seem to have been created to paralyse the prey. This suggests a specific action on parts of the nervous system. However, the solitary wasp venoms studied, contain many agonists and antagonists of synaptic transmission, and their paralysing action is very complicated. Besides a contribution of agonists to initiate and enhance the action of antagonists, one of the venoms contains two antagonists with different actions, and one of these antagonists enhances the effect of the other. The specific action of both toxins and their interaction will be discussed as an example of how nature enhances pesticide action through mixtures.
Extended summaries: Physicochemical and biophysical panel symposium enhancing pesticide action through mixtures
Authors: Gillard Grace
Published: November 2006

The following are summaries of papers presented at a meeting of the Physicochemical and Biophysical Panel of the Pesticides Group held on 14 October 1986 at the Society of Chemical Industry, 14 Belgrave Square, London SWIX8PS. The papers published here are entirely the responsibility of the authors and do not reflect the views of the Editorial Board of Pesticide Science.
Biochemical and toxicological differences in the modes of action of the benzoylureas
Authors: Neumann Rainer , Guyer Walter
Published: November 2006

The two insecticidal benzoylurea compounds, diflubenzuron and chlorfluazuron, show large differences in their toxicity against the larvae of insects like the tobacco budworm, Heliothis virescens, or the Egyptian cotton leafworm, Spodoptera littoralis, chlorfluazuron being about 100 times more toxic. This difference is due mainly to a much faster metabolism of diflubenzuron. Its half‐life within the larvae is about 5 h, compared to about 50 h for chlorfluazuron. Chlorfluazuron is also the much better ovicide of the two, following injection of the compounds into the females of H. virescens. Again the difference in the rate of metabolism is the main cause. The rate of excretion of the parent benzoylureas is relatively low, but their metabolites are excreted very quickly.
Genetic effects of phthalimide fungicides on diploid Aspergillus nidulans
Authors: Ziogas Basil N. , Georgopoulos Spyros G.
Published: November 2006

A few specimens of ‘Ridomil 25 WP’, a commercial formulation of metalaxyl, showed high genetic activity on a heterozygous diploid strain of Aspergillus nidulans. This activity was due to an impurity which was identified by mass and n.m.r. spectroscopy as captafol. This and the related fungicides captan, dichlofluanid, and tolyfluanid greatly increased the yield of euploid colour segregants from the diploid strain. At low captafol concentrations, most of the induced segregants resulted from mitotic crossing over but chromosome non‐disjunction or loss was also caused at high concentrations. Mitotic crossing over could be induced also by vapour‐phase action of captafol and captan. The mechanism by which these phthalimides may exert their genetic effects is discussed.
Dislodgeable residues and persistence of diazinon, chlorpyrifos and isofenphos following their application to turfgrass
Authors: Sears Mark K. , Bowhey Cindy , Braun Heinz , Stephenson Gerald R.
Published: November 2006

In laboratory experiments, residues of diazinon applied to turfgrass, Poa pratensis L., that could be dislodged by rubbing with cheese‐cloth, declined from c. 10% of the total applied when the grass was vigorously rubbed immediately after application to 0.3% after 1 day. Sunlight did not influence the rate of decline in dislodgeable residues or residues remaining on or within the leaf blades. In field experiments where 4.5 kg ha−1 of diazinon was applied in liquid or granular form, about 20 times more diazinon was dislodged from the liquid formulation immediately after application than from the granular. By 1 day after application the percentage of the total applied diazinon that could be dislodged was equal for both formulations. Rainfall had a significant effect on the amount dislodged from grass blades, but mowing did not. Similar rates of decline in the dislodgeable fraction of diazinon, chlorpyrifos and isofenphos were observed in field experiments. Recovery of the dislodgeable fraction declined to 0.25% or less of the total amount of any of these insecticides by 1 day after application. However, residues in the thatch remained sufficiently high for control of insects for up to 7 days after application for diazinon and 14 days for chlorpyrifos and isofenphos.
Assessment of the grain protectants chlorpyrifos‐methyl plus bioresmethrin, fenitrothion plus (1R)‐phenothrin, methacrifos and pirimiphos‐methyl plus carbaryl under practical conditions in Australia
Authors: Desmarchelier James , Bengston Mervyn , Davies Richard , Elder Brian , Hart Richard , Henning Ronald , Murray William , Ridley Edward , Ripp Eric , Sierakowski Charles , Sticka Rex , Snelson Jack , Wallbank Barry , Wilson Arnold
Published: November 2006

Methacrifos (22.5 g t−1) and the three protectant combinations chlorpyrifos‐methyl (10 g t−1) plus bioresmethrin (1 g t−1), fenitrothion (12 g t−1) plus (1R)‐phenothrin (2 g t−1) and pirimiphos‐methyl (4 g t−1) plus carbaryl (8 g t−1) were each applied to grain that was stored in at least 15 silos. Grain temperature and levels of protectant were regularly monitored, and samples from 12 storages using each treatment were taken for laboratory assays against Rhyzopertha dominica and Tribolium castaneum. Grain condition did not deteriorate during storage. Grain remained free of insects in 60 of the 63 storages treated; partial failure in the other 3 storages was attributed to low or irregular levels of protectant. The mean and range of residue values of all protectants were recorded as a function of time and the mean observed values corresponded to predicted values. In laboratory bioassay, the order of effectiveness against T. castaneum was methacrifos > chlorpyrifos‐methyl plus bioresmethrin > fenitrothion plus (1R)‐phenothrin = pirimiphos‐methyl plus carbaryl. The order of effectiveness against R. dominica was carbaryl plus pirimiphos‐methyl = (1R)‐phenothrin plus fenitrothion > methacrifos > bioresmethrin plus chlorpyrifos‐methyl.
A comparison of cypermethrin distribution on cattle hair after application of impregnated ear and tail tags
Authors: Taylor Stuart M. , Elliott Christopher T. , Blanchflower William J.
Published: November 2006

Ten dairy cows were separated into two groups of five. One group was ear tagged with a PVC ear tag containing 8‐5 g kg−1 cypermethrin in each ear. A PVC strip impregnated with the same quantity of cypermethrin was attached to the tail of each cow in the other group. The concentration of cypermethrin in hair samples from the neck, flanks and the anterior, sides and the posterior of the udder was measured for a period of 10 weeks after application. Concentrations were found to be high in those body areas nearest to the points of application, moderate on the flanks but low on the front and sides of the udder.
Contaminant and formulation analysis of MSMA using high‐pressure liquid chromatography — graphite furnace atomic absorption spectrophotometry
Authors: Pick Frans E. , De Beer Pieter R. , Prinsloo Susan M. , Van Dyk Louis P.
Published: November 2006

High‐pressure liquid chromatography with an ion‐exchange column combined with graphite furnace atomic absorption spectrometry was used to analyse commercial formulations of sodium hydrogen methylarsonate (MSMA). No arsenite or arsenate salts or dimethylarsinic acid were detected as contaminants in the formulations, and the MSMA concentrations were found to be in accordance with the concentrations given on the containers.
Hydrosoil residues and Hydrilla verticillata control in a central florida lake using fluridone
Authors: Schmitz Don C. , Leslie Andrew J. , Nall Larry E. , Osborne John A.
Published: November 2006

Fluridone was applied to a 98‐8‐ha lake in Orange County, Florida, USA, in five different treatment plots between October 1982 and February 1983 to control a severe infestation of Hydrilla verticillata. Hydrosoil residues and submersed aquatic plant biomass were monitored within the lake. Fluridone did not affect the submersed vegetation during the 4‐month fall‐winter treatment period. As water temperatures increased during spring, Hydrilla biomass declined at an average of 0.178 kg m−2 per month. By summer (192 days after last treatment), the target species could not be found within the lake. Fluridone residues were detected in the hydrosoil immediately following treatments and generally peaked coinciding with the decline in aquatic plant biomass. The maximum fluridone detected in the hydrosoil was only 5% of the 2.25 kg ha−1 applied, and this amount was obtained from outside of a treatment area. Residue concentrations were highly variable between sampling sites and sampling periods and unexpectedly increased 14 months after treatment. Winter‐killed marginal vegetation is a possible source of this increase. Detectable concentrations of fluridone, and vegetation control, persisted for a total of 86 weeks from the date of the last treatment and non‐detectable residues may have persisted after 86 weeks. This study indicates that a lower application rate might have provided adequate control of Hydrilla and possibly decreased residue concentrations in non‐target areas.
The physical and chemical properties of the herbicide cinmethylin (SD 95481)
Authors: Grayson B. Terence , Williams Karen S. , Freehauf Paul A. , Pease Rodney R. , Ziesel William T. , Sereno Richard L. , Reinsfelder Ronald E.
Published: November 2006

Cinmethylin (SD 95481), is a novel herbicide developed for the selective pre‐emergence control of many annual grass weeds in a wide range of temperate and tropical crops. Representing new herbicide chemistry, cinmethylin is in the cineole family.

Cinmethylin is a mobile colourless liquid with a boiling point of 313°C under an inert atmosphere at atmospheric pressure. It has a density of 1015 kg m−3 and a viscosity of 70–90 mPa s, both at 20°C. It is miscible in all proportions with most organic solvents but has a low solubility, 63 mg litre−1, in water. It has a vapour pressure of 10.2 mPa (20°C) and the vapour pressure/temperature relationship is given by loge P(Pa)=28.9–9816/T (K). The n‐octanol/water partition coefficient is 6850 and soil organic matter/water sorption coefficient (Kom) ranges between 165 and 235 over the three types of soil used in these studies.

Cinmethylin is stable in water over the pH range 3–11. Solutions of cinmethylin in water or solvents are reasonably stable to sunlight, though thin films on a quartz surface photooxidise mainly to an ester within 24 h. This rate can be reduced by the addition of photostabilisers or by sorption onto soil surfaces. In an inert atmosphere cinmethylin is stable to high temperatures, though, in air, oxidation occurs at temperatures above 100°C to give the same product as by photodecay.
Chlorophyll sensitised photodegradation of 2‐dimethylamino‐5, 6‐dimethylpyrimidin‐4‐ol
Authors: Dixon Stephen R. , Wells Clifford H. J.
Published: November 2006

The chlorophyll sensitised photodegradation of 2‐dimethylamino‐5, 6‐dimethylpyrimidin‐4‐ol (I), a hydrolysis product of pirimicarb, in the solid state on silica gel and in chloroform solution has been investigated. The product distribution in the solid state photodegradation was different from that in chloroform solution and was dependent upon the wavelength range of the incident radiation. When radiation of wavelength greater than 420 nm was used, the products formed in the chlorophyll sensitised degradation of I in the solid state were similar to those obtained when Rose Bengal or Methylene Blue were used as sensitisers. These results indicate that singlet oxygen is implicated in the sensitised photodegradation of I in the solid state. Numerous products were formed in each of the systems studied.
Studies on the comparative effectiveness of permethrin and deet against bloodsucking arthropods
Authors: Buescher Michael D. , Rutledge Louis C. , Wirtz Robert A.
Published: November 2006

A comparison was made of the effectiveness of permethrin and deet against Ornithodoros parkeri (Acari: Argasidae), Leptotrombidium fletcheri (Acari: Trombiculidae), Rhodnius prolixus (Heteroptera: Reduviidae), Phlebotomus papatasi and Lutzomyia longipalpis (Diptera: Psychodidae), Anopheles Stephensi, Anopheles albimanus, Aedes taeniorhynchus, Aedes aegypti and Culex pipiens (Diptera: Culicidae), Glossina morsitans (Diptera: Glossinidae) and Xenopsylla cheopis (Siphonaptera: Pulicidae), using dose‐response methods. At the ED95 (95% effective dose) level, deet was more potent (P<0.05) than permethrin against all species except O. parkeri and R. prolixus. In addition, the slope of the dose‐response line for deet was greater than that for permethrin against all species except O. parkeri and R. prolixus. Permethrin exhibited repellent and/or toxic effects, depending on the dose used and the individual tolerances of members of the insect test population.
Uptake, metabolism and effects of DDT, fenitrothion and chlorpyrifos on Tetrahymena pyriformis
Authors: Lal Sukanya , Saxena D. M. , Lal Rup
Published: November 2006

The uptake and metabolism of DDT, fenitrothion and chlorpyrifos were studied in cultures of the ciliate protozoan Tetrahymena pyriformis. When cultures were treated with DDT in concentrations varying from 0.01 to 0.5 μg ml−1, concentrations found in T. pyriformis were 3.8 to 335 μg g−1 dry weight. The accumulation of fenitrothion ranged from 28.7 μg g−1 in cultures treated with 1 μg ml−1 to 2260 μg g−1 in cultures treated with 10 μg ml−1. Under similar experimental conditions chlorpyrifos was accumulated from 24.7 to 15400 μg g−1. The patterns of uptake were dependent on the growth cycle, the ability of the organism to metabolise insecticide and the type of the insecticide used. Maximum accumulation of DDT, fenitrothion and chlorpyrifos occurred in 2, 4 and 6 h respectively. Tetrahymena metabolised DDT to DDD and DDE but failed to metabolise fenitrothion and chlorpyrifos.

The effects on growth and morphology of T. pyriformis were studied over a period of 5 days. Higher concentrations (10, 50 and 100 μg ml−1) of DDT inhibited only the growth of the organisms and did not change cell morphology. Fenitrothion was extremely toxic to the organisms and at 5 and 10 μg ml−1 cells became more or less spherical and died after 48 h. However, concentrations of 0.5, 1 and 2.5 μg ml−1 fenitrothion caused growth inhibition, but only at 2.5 μg ml−1 was this permanent. Chlorpyrifos inhibited the growth of the organisms at 1, 5 and 10 μg ml−1 but the morphology was affected only at 5 and 10 μg ml−1.
Activity of optical and geometrical isomers of the juvenile hormone analogue hydroprene on endogenous juvenile hormone levels in Larval Manduca sexta
Authors: Edwards J. P.
Published: November 2006

The geometrical and optical isomers of the insect juvenile hormone analogue hydroprene (ethyl (2E,4E)‐3,7,11‐trimethyldodeca‐2,4‐dienoate) were tested in vivo, both for ability to depress endogenous juvenile hormone titre and as juvenile hormone agents in larval Manduca sexta. The structure‐activity relationships of these isomers were found to be similar both for feedback inhibition of juvenile hormone levels, and for juvenile hormone activity as indicated by pigmentation changes in larval cuticle. In both cases, the (7S) (2E,4E) isomer was the most active of the materials tested.
Persistence and binding of DDT and gamma‐HCH in a sandy loam soil under field conditions in Delhi, India
Authors: Samuel Thomas , Agarwal Hari C. , Pillai Madathil K. K.
Published: November 2006

Persistence and binding capacity of [14C]p, p′‐DDT and [14C]y‐HCH were studied for one year in a sandy loam soil of Delhi, India, after surface treatment during monsoon, winter and summer seasons under field conditions. Both DDT and HCH dissipated more rapidly under the Indian subtropical climate than reported for temperate regions. In all three seasons, both insecticides dissipated most rapidly during the initial 60 days. However, in the final six months there was very little change in the residue levels. After one year, the final soil burden of DDT varied from 33 to 36% and of HCH from 14 to 15% of the initial concentrations in the different experiments. HCH bound more with the soil as, out of the total residues present after one year, more than 75% of HCH was in bound form compared with only 24% of DDT. The observed time for 50% initial dissipation of DDT ranged from 60 to 120 days, while in the case of HCH it varied from 30 to 45 days. However, the rate of loss of residues which persisted for more than 6 months was equivalent to a half‐life of between 500 and 10000 days for DDT, and between 700 and 2000 days for HCH, thus illustrating the very long persistence of aged residues. Since degradation of both insecticides was apparently minimal, the data indicate that dissipation of DDT and HCH was largely due to volatilisation.
Enantioselective transformation of the herbicides diclofop‐methyl and fenoxaprop‐ethyl in soil
Authors: Wink Ottmar , Luley Ulrike
Published: November 2006

The separate enantiomers of diclofop‐methyl and fenoxaprop‐ethyl were incubated with two soils under aerobic conditions. Rapid hydrolysis to the corresponding acids diclofop and fenoxaprop was observed. At various time intervals after soil treatment the parent compound and its free acid were extracted and the extracts were investigated by high‐performance liquid chromatography. The determination of the K:S‐ratio using a chiral stationary phase revealed that no racemisation of the esters took place. However, inversion of the hydrolysis products was observed. In both soils the acids with the S‐configuration showed a significantly higher inversion tendency than the acids with the R‐configuration. In one soil the S‐acids of both herbicides were inverted (50% inversion in 4–7 days) to yield, ultimately, a residue containing 70% R‐ and 30% S‐enantiomer.
Uptake of triadimenol through wheat caryopsis after application by seed treatment
Authors: Thielert Wolfgang , Steffens W. , Führ F. , Kuck K. H. , Scheinpflug H.
Published: November 2006

The uptake of triadimenol was investigated by offering radio‐labelled chemical exclusively through the caryopsis in a special experimental design with single seed grains in plexiglass holders. In totally‐treated caryopses about 5% and, in partially‐treated caryopses (embryo untreated), 4.5% of the applied radioactivity reached the winter wheat shoots after 21 days up to the third leaf stage. Uptake of active ingredient through the pathway pericarp‐testa‐endosperm‐scutellum‐seedling up to the third leaf stage D(13) was therefore confirmed. Furthermore, [14C] triadimenol was also translocated through the caryopses into the roots and was released to the nutrient solution.
Factors influencing entry of pesticides into soil water
Authors: Nicholls Peter H.
Published: November 2006

Leaching of pesticides and hence the risk of contamination of ground‐water depends on the physicochemical properties of the pesticide, the properties of the soil and the weather. Lipophilicity is the most important physicochemical property influencing the movement of un‐ionised pesticides through soil. Water solubility is usually only an important factor in leaching for a few moderately polar solids with high melting points. Organic matter content is the most important property of the soil for un‐ionised pesticides whilst the mobility of weak acids depends on soil pH. Permanent anions and weak acids can be very weakly adsorbed and hence might easily reach groundwater. Applications in autumn are more likely to reach groundwater than those in spring because soil temperatures are low and rainfall exceeds evaporation in winter, enabling mobile pesticides to penetrate to subsoils where degradation rates can be very slow. Concentrations of pesticide in water entering subsoils cannot be reliably simulated to an accuracy of better than an order of magnitude because the complex patterns of water flow and the slow diffusion processes of the pesticide are insufficiently understood. The consequences of applying a mobile pesticide to soil where drainage is impeded or where the water table is near the surface need to be anticipated before it is registered for treatment of the soil.
Uptake and utilisation of phosphonate ions by Phytophthora citrophthora and Nectria haematococca in relation to their selective toxicity
Authors: Barchietto Thierry , Saindrenan Patrick , Bompeix Gilbert
Published: November 2006

Phosphonate ions, which are degradation products of aluminium tris‐O‐ethyl phosphonate (fosetyl‐aluminium) in plant tissues, had more effect in vitro against Phytophthora citrophthora than against Nectria haematococca.

Both fungi were able to take up phosphonate ions. This uptake was realised against a concentration gradient and was affected by metabolic inhibitors. When examined over a 0.5 to 6.0 mm concentration range, phosphonate was carried by a single transport process obeying Michaelis‐Menten kinetics, with a low affinity (high K′m). Further analysis by means of Hofstee plots indicated a somewhat faster phosphonate uptake by N. haematococca than by P. citrophthora, so it appears clearly that uptake was not involved in the selective toxicity of this compound.

The continuous uptake of phosphonate by N. haematococca is correlated with an important utilisation of this ion by the fungal cells. This fact could be explained by a detoxification process corresponding to the oxidation of phosphonate to phosphate which could account for the low sensitivity of this fungus.

Phosphonate uptake by P. citrophthora reached a maximum level after 20 min and then decreased to a constant level over the following period. During the incubation period phosphonate was incorporated directly without oxidation into phosphate. This incorporation could lead to a disturbance of the cell metabolism.
Fungicide seed treatments to improve seedling emergence of perennial ryegrass Lolium perenne and the effect of different cultivars and soils
Authors: Lewis Graham C.
Published: November 2006

Seeds of perennial ryegrass Lolium perenne treated with four fungicides, benomyl, captan, iprodione and metalaxyl, used singly and in all combinations were sown in soil in pots. The soil was maintained at a low moisture content to predispose the seedlings to pre‐emergence infection by soil‐borne fungi. Thirteen of the fifteen fungicide treatments significantly increased seedling emergence and all but one contained benomyl and/or captan. In another pot experiment, a combination of benomyl and captan was tested against four similar treatments, carbendazim+captan, thiabendazole+captan, thiabendazole+metalaxyl and thiabendazole+thiram and also drazoxolon. Only benomyl+captan and drazoxolon did not increase seedling emergence significantly. A natural infection of the seedlings by powdery mildew Erysiphe graminis was reduced significantly by all treatments except thiabendazole+thiram and drazoxolon. Only car‐bendazim+captan significantly increased the dry weight of seedlings per pot 98 days after sowing. Benomyl+captan seed treatment significantly increased seedling emergence in 9 of 16 soils collected from widespread sites. One perennial ryegrass cultivar, Parcour, was used in the above experiments and in a comparison with 12 other diploid cultivars its response to benomyl seed treatment was about mid‐range.
N‐benzoyl‐N′‐phenoxyphenyl‐ and N‐benzoyl‐N′‐carboxyphenyl ureas: A review of their chemical synthesis and biological profiles
Authors: Hofmeister P. , Künast C. , Lange A.
Published: November 2006

Some highly active and broad‐spectrum representatives of the phenoxyphenyl‐ and carboxyphenyl urea groups of compounds are described. The products are relatively easily accessible, simple and economical to produce in high yield. Excellent biological activity has been detected using S. littoralis and a broad‐spectrum activity has been found on Lepidoptera, Diptera, Coleoptera and Hemiptera.

Using two examples of phenoxyphenyl acylureas the high level of selectivity to certain larval stages has been shown in various noctuids. By altering the ester function to an ether group some indications of systemic activity could be achieved.

Disturbances caused in cuticle formation have been investigated in ultrastructural studies of regenerating cockroach legs.
Iodometric calibration of organophosphorus insecticides and measurement of hydrolysis products
Authors: Desmarchelier James M.
Published: November 2006

Dialkylphosphoro‐thioic and ‐dithioic acids, hydrolysis products of most organophosphorus insecticides, react stoichiometrically with iodoacetic acid, under controlled conditions, to release iodide. At room temperature, dialkylphosphorodithioic acids react with iodoacetic acid at pH 7–9, and dialkylphosphoro‐thioic and ‐dithioic acids react with iodoacetic acid at pH 2 and below. This last reaction may be used for the determination of breakdown products in the presence of insecticides, such as fenitrothion, that are sufficiently stable to acid hydrolysis. The methods are suitable for measuring both active ingredients and hydrolysis products in formulations and in waterdiluted sprays.
Sterol metabolism in wheat treated by N‐substituted morpholines
Authors: Costet‐Corio Marie‐France , Benveniste Pierre
Published: November 2006

Wheat caryopses were treated with racemic fenpropimorph. As shown previously in other plant species, 9(β,19‐cyclopropyl sterols were found to accumulate markedly. A distinctive feature was a remarkable accumulation of 31 ‐norcyclobranol, a very rare sterol in nature. A8‐sterols were also identified. The ratio A8‐sterols: cyclopropyl sterols was shown to depend greatly on the configuration of the methyl substituent in position 2 of fenpropimorph. Whereas cyclopropyl sterols predominated in the case of seedlings treated with the (2S)‐2‐methyl enantiomer, A8‐sterols were shown to be very abundant in plants treated with the (2R)‐2‐methyl enantiomer. A8‐sterols were shown also to be more abundant in leaves than in roots. Experiments were conducted to find out whether the phytotoxic response of plants to fenpropimorph could be ascribed to its action on sterol biosynthesis. From the results obtained it appears that this is not the case and thus the phytotoxic effect is probably related to a cellular target other than sterol biosynthesis.
Partial purification and properties of an esterase from tomato cell suspension cultures hydrolysing the pyrethroid insecticide cyfluthrin
Authors: Preiss Ursula , Wallnöfer Peter R. , Engelhardt Gabriele
Published: November 2006

An esterase which hydrolyses the pyrethroid insecticide cyfluthrin, was isolated from tomato cell suspension cultures and purified 10‐fold. The apparent molecular weight of the enzyme was estimated to be 32 000 Dalton, the pH‐optimum 8‐0, and the temperature optimum 35°C. The esterase showed a low substrate specificity and hydrolysed certain esters, e. g. ethyl 4‐nitrobenzoate, p‐nitrophenyl acetate and dinoseb acetate, whereas ethyl butyrate and the organophosphates demeton‐S‐methyl sulfoxide and paraoxon could not be hydrolysed. Because of the additional strong inhibition of the enzyme by these organophosphates the cyfluthrin hydrolase is suggested to belong to the B‐esterase type. An apparent Km‐value of 6‐25 × 10−4 mol litre−1 was obtained for p‐nitrophenyl acetate as substrate.
Mechanism of cellular absorption of imidazolinones in soybean (Glycine max) leaf discs
Authors: van Ellis Mary Reider , Shaner Dale L.
Published: November 2006

The mechanism of uptake of imazapyr, imazethapyr, and imazaquin into soybean leaf discs was determined. Uptake into the leaf discs was linear with respect to external concentration from 10−8 to 10−3 M. Metabolic inhibitors and uncouplers (DNP, FCCP, CCCP, NaN3, NaCN, DCMU) decreased uptake 58 to 85 %. Uptake was also sensitive to temperature, with maximum uptake occurring at 23°C. The Q10 for uptake between 13 and 23°C was 1‐7. The uptake of all 3 imidazolinones was sensitive to the pH of the uptake solution. Maximum uptake occurred at pH 4. However, there were differences in the rate of uptake among the three herbicides. Imazaquin was absorbed the most rapidly followed by imazethapyr and then imazapyr. These differences in uptake reflected the differences in the lipophilicity of the chemicals at pH 4 and 7. The apparent Kow of imazaquin, imazethapyr and imazapyr at pH 4 was 7‐7, 1‐4, and 0‐1, respectively, and at pH 7 was 0‐04, 0‐02, and 0‐004, respectively. Based on these results the mechanism of uptake is probably best explained by ion trapping.
Methyl bromide residues in fresh cherries: Effects of parameters of fumigation
Authors: Sell Charles R. , Klag Narcy G. , Burditt Arthur K.
Published: November 2006

Determinations were made of the desorption rate of residual free methyl bromide from fresh sweet cherries during the aeration period that followed fumigation with methyl bromide. The results showed that the desorption followed approximately pseudo‐first‐order kinetics. Ventilation rates during aeration, which were greater than or equal to the rates used at commercial fumigation chambers, had no effect on desorption rate. The concentration and persistence of residue was dependent on two parameters of the fumigation: the load factor, which is the ratio of the volume of cherries to the volume of the fumigation chamber, and the pulp temperature of the cherries. The relationship between load factor, pulp temperature and desorption rate was used to derive a mathematical model of the desorption of methyl bromide from cherries. The model gave good estimates of residue concentrations over a wide range of load factors, pulp temperatures and aeration periods, and was used to predict the length of the aeration period required to reduce the residue to a proposed tolerance of 0‐1 mg kg−1.
The herbicidal activity of 3‐substituted 1‐phenylureas
Authors: Barnes Keith F. , Browning Ian R. , Clark Nigel G. , Clark Ronald J.
Published: November 2006

A variety of 1‐phenylureas, substituted in the 3‐position with one acyl, alkoxycarbonyl or cyano group, and optionally with a lower alkyl group, have been synthesised and assessed for pre‐ and post‐emergence herbicidal activity against a range of monocotyledonous and dicotyledonous weed species. Generally, activity was associated only with compounds containing two small substituents in the 3‐position. Their possible metabolic fate is discussed in the light of comparisons with the activity of the commercial herbicides, fenuron, monuron and diuron, and their de‐methylated derivatives.
The herbicidal activity of 1‐substituted 1‐phenylureas
Authors: Barnes Keith F. , Browning Ian R. , Clark Nigel G.
Published: November 2006

A selection of 1, 1‐dialkyl‐3‐phenylureas, additionally substituted in the 3‐position by methanesulphonyl, cyano, alkoxycarbonyl or methyl, have been synthesised and assessed for pre‐ and post‐emergence herbicidal activity against a variety of monocotyledonous and dicotyledonous weed species. The range of activities is compared with those of the structurally‐related commercial herbicides, fenuron, monuron and diuron, into which the novel compounds could be metabolised (‘lethal synthesis’).
Management of resistance in horticultural pests and beneficial species in New Zealand
Authors: Suckling David M. , Walker Jim T. S. , Shaw Peter W. , Markwick Ngaire P. , Wearing C. Howard
Published: November 2006

Two related insecticide resistance management programmes are under way in New Zealand horticulture. The first aims to limit the spread and impact of azinphos‐methyl resistant lightbrown apple moth (LBAM) in an applegrowing district. In the second, the introduction of pyrethroid (SP) resistance in organophosphate‐resistant (OP) Typhlodromus pyri makes it possible to undertake biological control of the European red mite that is compatible with SP and OP control of orchard pests.

In the LBAM programme the resistant zone, which includes alternative host‐plant reservoirs, has been delineated by detailed resistance monitoring with topical application of males caught using female sex pheromone. In that zone, chlorpyrifos, to which the azinphos‐methyl resistant LBAM has low cross‐resistance, is used in the short term to control resistant moths, while alternative measures (e. g. other insecticides and mating disruption) are investigated. Recognition of the importance of immigration from alternative host plant reservoirs has led to specific tactics such as the application of pyrethroids to non‐crop areas. This resulted in a significant decrease of the resistant population. So far, however, SPs have not been registered in apple orchards because they kill OP‐resistant predatory mites which control the European red mite, and also because of the lack of residue tolerances for SPs in some overseas markets.

Following the assessment of the potential value of pyrethroids in pipfruit, DSIR started field selection for pyrethroid resistance in predatory mites, which was later expanded to include laboratory selection. The successful development of pyrethroid‐resistant predators which retain organophosphate resistance is permitting the introduction of biological control of European red mite compatible with the use of these two classes of insecticides for control of other pests.

In future, the lepidopterous pests on New Zealand apples may be controlled by pyrethroids, scales and other minor pests by organophosphates, and European red mite by multi‐resistant predatory mites.
Insecticide resistance in Heliothis armigera in Australia
Authors: Daly Joanne C.
Published: November 2006

A voluntary insecticide resistance management strategy for the control of H. armigera was implemented in Australia in 1983 after an outbreak of resistance to synthetic pyrethroids. This strategy restricts the use of pyrethroids to three sprays within a 42‐day period in summer. The use of endosulfan is also restricted and rotation of other pesticides is encouraged. The effectiveness of the strategy is monitored by tests on larvae collected from two major cotton areas and from unsprayed crops in northern New South Wales. Research is under way to determine the genetic basis of two of the three mechanisms involved in resistance. One genetic component is associated with the mixed‐function oxidases. Selection in the field for this semi‐dominant gene (or genes) occurs in larvae 4 days or more old. It is not possible to evaluate directly the success of this strategy because there is no control area where it has not been implemented. While the long‐term outcome of the strategy is uncertain, it is likely that resistance will increase in frequency.
Problems of control of insecticide‐resistantPlutella xylostella
Authors: Cheng E. Y.
Published: November 2006

In the different regions of SE Asia, resistance problems in the diamondback moth (DBM), Plutella xylostella, are comparable, and depend on the type of insecticide used to control this pest. Resistance is especially high to insecticides metabolised by mfos (multifunctional oxidases), but since the detoxification of each such insecticide depends on different mfo(s), there is little cross‐resistance between insecticides. Thus, carbaryl, carbofuran and the synthetic pyrethroids, all detoxified by mfos, show little cross‐resistance. Resistance to cartap and some organophosphorus insecticides is much lower, and is often unstable. Those compounds are therefore essential in the rational control of DBM. The cross‐resistance relationships within the traditional insecticides have mostly been worked out. It is thus possible to use alternate spraying schedules with insecticides conferring minimum cross‐resistance potential. Alternating insecticides is better than using mixtures, because DBM can develop multiple resistance through treatment with mixtures.

DBM has now developed resistance to the newly‐introduced IGRs and other experimental control agents. Possible resistance to these as well as to future DBM control agents has been examined, and their resistance‐inducing ability and cross‐resistance characteristics examined. Experience in monitoring the spectrum together with the strength of resistance of field populations of DBM suggest that control can only be achieved by wellplanned rational chemical control programs.
Present status and countermeasures of insecticide resistance in agricultural pests in China
Authors: Tang Z. H. , Gong K. Y. , You Z. P.
Published: November 2006

Of the 23 species of agricultural pest known to resist insecticides in China, 4 are cotton pests, 4 rice pests and 5 are pests of brassicae. In the green rice leafhopper, malathion resistance is caused by increased carboxylesterase (CarE) activity, which plays a more important role in the resistance to dimethoate than the mixed‐function oxidases (mfos). The in‐vitro and in‐vivo results are in agreement with studies of synergism of malathion and dimethoate by TPP and EBP. These synergists delay the development of resistance, and EBP when added to malathion has limited the development of resistance to malathion in the green rice leafhopper. In the cotton aphid, resistance to organophosphates involves several factors: acetylcholinesterase (AChE) insensitivity, high CarE activity, slight (× 2) increase in glutathione S‐transferases (GSH‐ases), mfo activity as well as reduced penetration. In vitro, the I50 of the insensitive AChE is × 14 that of S aphids, and anaphthyl‐acetate CarE hydrolysing activity is 70 times greater in R than in S aphids. Insecticide mixtures, alternation or rotation can delay build‐up of resistance; resistance to malathion and trichlorfon was delayed in Culex pipiens pallens when the two insecticides were used together. Used singly each insecticide selected for high resistance within 25 generations. Mosaic rotation of dimethoate and fenvalerate delayed the onset of insecticide resistance in Lipaphis erysimi pseudobrassicae.