bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surfactant‐enhanced foliar uptake of some organic compounds: Interactions with two model polyoxyethylene aliphatic alcohols
Authors: Stock David , Edgerton Bernadette M. , Gaskin Robyn E. , Holloway Peter J. 
Published: November 2006

AbstractInteractions occurring during the surfactant‐enhanced foliar uptake of seven model organic compounds were examined using two homogeneous surfactants, hexaethylene glycol monotridecyl ether (C13E6) and hexadecaethylene glycol monododecyl ether (C12E16). Surfactant–compound and compound–surfactant interactions were detected by measurement of their relative uptake rates following application of c. 0·2 μl droplets of the corresponding radiolabelled formulations. The magnitude of surfactant–compound interaction was found to vary according to the physicochemical properties of both the compound and the surfactant, and was influenced by surfactant concentration and target plant species. Interactive and non‐interactive mechanisms, both leading to substantial enhancement of compound uptake, could be identified, but their precise nature could not be elucidated. Although penetration of C13E6 into the site of application appeared to be essential in order to activate the uptake of a compound, substantial absorption of C12E16 was not always required to produce the same effect. The results are discussed in the light of possible sites and modes of action for activator polyoxyethylene surfactant adjuvants.
Determination of mobilities of organic compounds in plant cuticles and correlation with molar volumes
Authors: Bauer Hubert , Schönherr Jörg 
Published: November 2006

AbstractMobilities of selected pesticides in plant cuticles have been measured using unilateral desorption from the outer surface (UDOS). The outer layer of the cuticle limits the rate of foliar uptake and solute mobilities in this layer have been determined. The primary parameter measured was the first‐order rate constant of desorption. From these rate constants, permeances, half‐times of penetration and diffusion coefficients could be calculated. Rate constants were lowest in bitter‐orange (Citrus aurantium L.) leaf cuticles and this cuticle turned out to be very size‐selective, as rate constants decreased by a factor of 264 when molar volumes increased by only a factor of about three. Rate constants measured using green‐pepper (Capsicum annuum L. cv. Bell Boy) fruit cuticles were larger by one to two orders of magnitude and this cuticle was considerably less size‐selective. A good correlation between rate constants and molar volumes was observed for cuticles from both plant species, which means that rate constants can be estimated from molar volumes of pesticides. Rate constants of desorption are mobility parameters which do not depend on lipophilicity of solutes. Thus, it is now possible to separate the contributions of mobilities and solubilities in cuticles to rates of foliar uptake of pesticides.
Leaching of atrazine and hexazinone from Abies nordmanniana (Steven) spach plantations
Authors: Felding Gitte 
Published: November 2006

AbstractThe content of the herbicides atrazine and hexazinone was measured in drainage water from seven to ten‐year‐old plantations grown with Abies nordmanniana (Steven) Spach on two clayey soils in Denmark. The concentrations of atrazine varied between 0.06 and 7.79 μg litre−1. The concentrations of hexazinone were different at the two locations, ranging from 0.07 to 2.09 μg litre−1 at Bremersvold and from 3.47 to 42.66 μg litre−1 at Koege. Metabolites of both herbicides were identified.
Effects of nonionic surfactants on cuticular sorption and penetration of 2, 4‐dichlorophenoxy acetic acid
Authors: Tan Siyuan , Crabtree Garvin D. 
Published: November 2006

AbstractSurfactants increase the uptake of some foliar‐applied chemicals to a greater extent than would be expected from their effects on surface tension and spray coverage. This study of the uptake of 2, 4‐D [(2, 4‐dichlorophenoxy)acetic acid] evaluated the effect of surfactants on penetration through and sorption by isolated cuticles of apple leaves. [14C]2, 4‐D was placed in glass chambers affixed to enzymatically isolated adaxial apple leaf cuticles after the cuticle segments had been treated with various surfactants. The same surfactant pretreatments were included in sorption studies in which cuticle segments were immersed in [14C]2, 4‐D for 96 h. Quantities of 2, 4‐D passing through or sorbed by the cuticle were determined. Similar experiments were conducted with unaltered cuticles and cuticles dewaxed with chloroform. The hydrophile‐lipophile balance (HLB) of polyethylene‐glycol‐based surfactants was inversely related to the sorption of those surfactants by the cuticles and penetration of 2, 4‐D. Sorption of 2, 4‐D by apple leaf cuticles was unaffected by surfactant pretreatment. Dewaxed cuticle membranes showed a similar response to 2, 4‐D penetration and sorption following the surfactant pretreatment.
Oil formulation of pyrethroids for contamination of tsetse flies (Glossina spp.) through tarsal contact with treated targets
Authors: Langley Peter A. , Perschke Helmut , Hussain Manzoor 
Published: November 2006

AbstractMosquito netting side panels of targets used for tsetse control were treated with lambda‐cyhalothrin, either dissolved in a mixture of acetone and a chlorohydrocarbon oil, ‘Cereclor’® > (ICI, UK) or as a conventional wettable powder formulation suspended in water. Treated netting samples were weathered under natural conditions in full sun in Zimbabwe. Following brief tarsal contact of test insects (adults of Glossina morsitans morsitans Westw.) with treated netting, the wettable powder induced 100% knockdown for four months after treatment but 24‐hour mortality levels were reduced from the third month onwards. The oil formulation induced 100% knockdown for up to ten months following treatment and 100% mortality at 24 hours for up to eight months. Chemical assay showed that after two months there had been a rapid reduction in the amount of active ingredient to only 20% of that applied using the wettable powder, whereas the oil formulation took seven months to fall to this level. Provided that at least 5% of the original amount of pyrethroid remained on the fabric it was quite effective and the superiority of the oil formulation was further enhanced by the observation that the starting concentration was only 25% of that of the wettable powder.
Indol‐3‐ylacetic acid‐ and calmodulin‐regulated Ca2+‐ATPase: A target for the phytotoxic action of hexachlorocyclohexane
Authors: Sharada Khandavilli , Salimath Bharathi P. , Shetty H. Shekar , Gopalakrishna N. , Karanth K. 
Published: November 2006

AbstractIn rice seedlings, the organochlorine insecticide hexachlorocyclohexane (HCH) and its four major isomers—α,β, γ, and δ—have been shown to elicit their phytotoxic action by interacting with indol‐3‐ylacetic acid (IAA)‐regulated growth and Ca2+‐ATPase activity. When rice seedlings were grown in the presence of 0.34 mM HCH, seedling vigour was reduced to 33% of the control. A similar effect was observed when seedlings were grown in the presence of the γ and δ isomers, but not with the α and δ isomers of HCH. This reduced vigour could be restored by treating the seedlings with 100 nM IAA, suggesting that HCH and its isomers (γ and δ) limit either IAA synthesis or action or both. In a microsomal fraction from rice seedlings grown in the presence of either HCH or its isomers, the calmodulin‐regulated Ca2+‐ATPase activity was inhibited as follows: technical HCH = 46%, α isomer = 80%, β isomer = 72%, γ isomer = 65% and δ isomer = 62% of the control value, respectively. TLC analysis suggested that the various isomers of HCH are metabolised by the plant, except for the δ isotner, which accumulated. This isomer, along with the degraded products of other isomers, may be responsible for the phytotoxic action of HCH.
Activity of rocaglamide, an insecticidal natural product, against the variegated cutworm, Peridroma saucia (lepidoptera: noctuidae)
Authors: Satasook Chutamas , Isman Murray B. , Wiriyachitra Pichaet 
Published: November 2006

AbstractPhysiological and behavioural effects of rocaglamide, an insecticidal natural product, were determined for the variegated cutworm, Peridroma saucia, using different bioassays. Rocaglamide inhibited growth of neonate P. saucia in a dose‐dependent manner when incorporated into an artificial diet. The dietary EC50 (effective concentration inhibiting growth by 50% relative to controls) was 1·37 mg kg−1. Lethal doses causing 50% mortality (LD50) of fourth‐instar larvae were 0·32 and 0·34μg larva−1 for topical and oral administration, respectively, based on a 96‐h observation period. Mortality did not become significant until at least 72 h following administration. Rocaglamide applied to cabbage leaf discs or incorporated into artificial diet had a moderate antifeedant effect towards larvae in choice tests. Nutritional experiments with fourth‐instar larvae using dietary exposure or following topical application confirmed that rocaglamide possessed both antifeedant and toxic effects. Direct assays of feeding behaviour indicated that behavioural effects could not account for the complete bioactivity observed. Significant impairment of larval growth following topical administration, concomitant with reduced food consumption, suggests that rocaglamide may act partially through central inhibition of the feeding process, leading to anorexia.
Bioaccumulation and elimination of endosulfan in zebra fish (Brachydanio rerio)
Authors: Toledo M. Cecilia F. , Jonsson CláUdio M. 
Published: November 2006

AbstractThe bioaccumulation and elimination of endosulfan in zebra fish (Brachydanio rerio) were investigated in a semi‐static bioassay. The pesticide mean concentration in water was 0.3 μg litre−1 and the level of endosulfan residues (α‐+β‐isomers+endosulfan sulfate) in the exposed fish at day 21 was 0.81 (±0.12) μg g−1 body weight. The estimated value of the bioconcentration factor (BCF) was 2650 (±441), the total endosulfan residues being eliminated with a biological half‐life of four days. Histopathological studies showed predominantly lipid accumulation in the liver and necrotic focus in the gills of exposed fish.
Interaction of azole fungicides and related compounds with cytochrome‐P450 isozymes from Penicillium italicum in in‐vitro assays
Authors: Kapteyn Johan C. , Milling Richard J. , Simpson Donald J. , De Waard Maarten A. 
Published: November 2006

AbstractThe interaction of various sterol demethylation inhibitors (DMls) and experimental compounds with cytochrome‐P450‐dependent sterol 14α‐demethylase (P45014DM) from Penicillium italicum was studied by difference spectroscopy using a preparation of microsomal P450 isozymes and assays with cell‐free extracts capable of synthesizing ergosterol from [14C]mevalonate. The EC50 values (concentrations of compounds which inhibited radial growth of P. italicum by 50%) of the compounds ranged from 3 × 10−8 M to levels higher than 10−3 M. All the compounds investigated gave type II difference spectra and interfered with the binding of carbon monoxide (CO) to microsomal P450 isozymes. However, the differences in the IC50 values (concentrations of compounds which caused 50% of maximal type II spectral change) between compounds and their inhibition of CO binding did not correlate with the fungicidal activity of the compounds. Hence, neither type II difference spectra nor CO‐displacement tests with microsomal preparations from this fungus can be used for studying the selective fungitoxicity of azoles. Data obtained using the cell‐free sterol 14α‐demethylase assay revealed larger differences between the compounds in their inhibition of sterol 14α‐demethylation. The I50 values (concentrations of compounds which inhibited cellfree sterol biosynthesis by 50%) varied from 4.3 × 10−9 to 4.4 × 10−5 M. This assay was able to rank the compounds in order of fungitoxicity, but the I50 and EC50 values did not correlate quantitatively. Consequently, the observed differential inhibition of P45014DM activity between the compounds cannot fully explain their selective fungitoxicity. Additional mechanisms must be involved. The present study supports the general opinion that the affinity of azoles for P45014DM depends on the nature of their N1 substituent. However, it was demonstrated that the nature of the azole moiety was also of importance in determining the affinity of DMIs for P45014DM.
Structure‐activity relationships of insecticidal amides from Piper guineense root
Authors: Gbewonyo Winfred S. K. , Candy David J. , Anderson Moray 
Published: November 2006

AbstractThe structure‐activity relationships between five amides previously isolated from the root extract of Piper guineense Schum and Thonn were studied. The methyl‐terminated amides, pellitorine and kalecide, were found to be more polar and caused higher knockdown, but showed less lethal action against insects than their methylenedioxyphenyl‐terminated counterparts, pipercide and guineensine. Guineensinamide showed weak activity and this was correlated with higher unsaturation and the presence of a pyrrolidyl group in the molecule. There was an association between the polarity of the amides and the recovery of the insects from their effects, much more recovery being observed with the methylterminated than with the methylenedioxyphenyl‐terminated amides. Electrophysiological investigations of the effects of pellitorine and pipercide on miniature excitatory postsynaptic potentials (MEPSPs) from the locust retractor unguis nerve‐muscle preparation showed that the amides caused a reduction in both the frequency and amplitude of MEPSPs, pipercide being between 100 and 1000 times more effective than pellitorine. An action of the amides on presynaptic transmission is suggested. The effects of pipercide and pellitorine on the isolated nerve‐muscle preparation were correlated with the symptoms of poisoning at the whole animal level.
Phototransformation of the insecticide hydramethylnon in aqueous systems
Authors: Chakraborty Subhasish K. , Bhattacharyya Anjan , Chowdhury Ashim 
Published: November 2006

AbstractSunlight irradiation of hydramethylnon in aqueous media of different pH values resulted in 80‐94% transformation within 10h. The rate of disappearance of the insecticide was affected marginally by the initial pH of the reaction medium. After 10 h irradiation, eight photoproducts were formed. Three products were isolated as pure crystalline substances and the structures of two of these (I & III) were characterised by mass and NMR spectroscopy. The reaction mechanisms involved in the formation of photoproducts are discussed.
Study of the enhancement of herbicide activity and rainfastness by an organosilicone adjuvant utilizing radiolabelled herbicide and adjuvant
Authors: Roggenbuck Frank C. , Penner Donald , Burow Richard F. , Thomas Bryan 
Published: November 2006

Abstract‘Sylgard® 309’ organosilicone surfactant is a very effective adjuvant for broadleaf weed control with a number of herbicides. It is also effective in providing rainfastness lo these post‐emergence herbicide applications. To elucidate the basis for herbicide activity enhancement and rainfastness, the absorption of [14C]acifluorfen, [14C]bentazone and [14C]‘Sylgard 309’ were studied. Non‐ionic surfactants and crop oil concentrates were used as adjuvants with [14C]acifluorfen and [14C]bentazone, respectively, for purposes of comparison. Maximum absorption of [14C]acifluorfen and [14C]bentazone was obtained within 15 min after herbicide application with the organosilicone, versus ≥ 24 h with the convenlional adjuvants. [14C]‐Organosilicone absorption closely paralleled that of the [14C]‐herbicides. The organosilicone appears to exert its action by increasing greatly herbicide absorption. The enhancement effect did not appear to be a function of reduced surface tension. Rainfastness appeared to be a result of greatly accelerated herbicide penetration through the leaf cuticle in the presence of the organosilicone.
Oils for weed control: Uses and mode of action
Authors: Gauvrit Christian , Cabanne Ferdinand 
Published: November 2006

AbstractThe role of oils in herbicide treatments is reviewed, both in terms of their own intrinsic activity and of their enhancement of the performance of other herbicides. The phytotoxicity of oils can be related to their physical properties. Their efficacy as adjuvants can vary with the plant/pesticide combination involved, and differences may also be observed between oils of mineral and vegetable origin. The possible mechanisms involved in the enhancement of activity by oils are discussed and areas of work that might elucidate these fun her are indicated.
Influence of wetting agents on the foliar uptake and herbicidal activity of glufosinate
Authors: Köcher Helmut , Kocur Jean 
Published: November 2006

AbstractThe influence of four different wetting agents on the foliar retention, uptake and herbicidal activity of the glutamine synthetase inhibitor, glufosinate, was examined in growth‐chamber experiments on barley (Hordeum vulgare L. cv Roland) and barnyard grass (Echinochloa crus‐galli (L.) P.B.) as test species.The non‐formulated monoammomum salt, glufosinate‐ammonium, was applied as a spray, either alone or mixed with a wetting agent. The dose rates of herbicide and wetting agent were 0.5 g a.i. litre−1 and 2.0 g litre−1, respectively, on barnyard grass, and 2.0 g a.i. litre−1 and 60 g litre−1, respectively, on barley. Herbicide damage, rated 10 days after spraying, was greatest when glufosinate was used with a sodium C12/C14‐alcohol‐diglycolether sulfate (FAEO‐sulfate) and least with polyoxyethylene (POE)(8) tridecyl ether; intermediate effectiveness was obtained with a combination of herbicide and a POE(15) tridecyl ether or POE(15)‐tallow amine.The activity of the target enzyme, glutamine synthetase, measured 2 h after spraying, was reduced most when FAEO‐sulfate was present and least with POE(8) tridecyl ether.The behaviour of the glufosinate wetting agent solutions on plant foliage was analysed by measurements of spray retention, droplet contact angles and foliar uptake of [14C]glufosinate. The results led, for both grass species, to the conclusion that differential ability of the wetting agents to enhance the permeation of glufosinate from the leaf surface deposit into the leaf tissue was the main factor responsible for the differences in herbicidal effectiveness of the glufosinate/wetting agent combinations used in this study.
British and European community regulations and registration requirements for non‐pesticidal co‐formulants in pesticides and for adjuvants
Authors: Chapman Peter J. , Mason Robert D. 
Published: November 2006

AbstractPesticides in Great Britain are subject to legislation that requires them to be approved by Ministers. Specific data for non‐pesticidal co‐formulants are not generally required but are encompassed within the requirements for the formulated pesticide in which they are present. Adjuvants, substances without significant pesticidal properties which enhance the effectiveness of a pesticide when added to that pesticide, can be used with pesticides only in accordance with the approval of that pesticide or as varied by lists of authorised adjuvants published by Ministers. Data must be supplied for adjuvants to appear on this list. National legislation on pesticides is soon to be amended to take account of a European Community Directive which seeks to harmonise registration requirements throughout the Community. It is as yet unclear how this will affect registration of co‐formulants and adjuvants.
Extended summaries sci pesticides group symposium third international symposium on adjuvants for agrochemicals. Structure and chemistry of plant cuticles
Authors: Holloway Peter J. 
Published: November 2006

AbstractThe following are extended summaries based on papers presented at a meeting of the Physicochemical and Biophysical Panel of the SCI Pesticides Group, held on 3‐7 August 1992 at Churchill College, Cambridge University. Cambridge, UK. The summaries published here are entirely the responsibility of the authors and do not necessarily reflect the views of the Editorial Board of Pesticide Science.
High‐performance liquid chromatographic method for the determination of carbendazim residues in crops, grains, and wines with fluorescent detection
Authors: Regis‐Rolle Sylvaine D. , Bauville GéRard M. 
Published: November 2006

AbstractA normal‐phase high‐performance liquid chromatographic method is described for the determination of carbendazim in wine, cereals and fruits. Residues are extracted from samples with methanol. Preliminary liquid partitioning into hexane may be necessary, according to the crops, followed by liquid partitioning from aqueous solution into dichloromethane. Purification is performed by silica‐column chromatography or with a silica solid‐phase extraction cartridge. Determination and quantification are made by HPLC using an aminobonded stationary phase with fluorescent detection at 285/315 nm. Recoveries range from 80 to 95% for various fortification levels. The method provides a minimum detectable amount below 0.1 ng and quantification limits for various samples are between 0.01 mg kg‐1 and 0.1 mg kg‐1.
Studies on octylphenoxy surfactants: XI. Effect on NAA diffusion through the isolated tomato fruit cuticular membrane
Authors: Knoche Moritz , Bukovac Martin J. 
Published: November 2006

AbstractThe effect of a homologous series of octylphenoxy surfactants [2‐{α‐[4‐(1,1,3,3‐tetramethylbutyl)phenoxy]poly(2‐ethoxy)}ethanol;‚ Triton‐X’︁ series], with five (TX‐45), 9–10 (TX‐100), 16 (TX‐165) and 40 (TX‐405) units of ethylene oxide (EO) on penetration of NAA [2‐(1‐naphthyl)acetic acid] through enzymatically isolated tomato (Lycopersicon esculentum Mill.) fruit cuticles was investigated. Surfactant effects on NAA flux were related to EO chain length and to surfactant concentration, compared on a basis relative to the critical micelle concentration (CMC, 2.5 × CMC and CMC/2.5). At concentrations above the CMC, TX‐45 and TX‐100 increased NAA flux 2.5‐ and 1.5‐fold, respectively, while TX‐165 was without effect and TX‐405 decreased NAA flux 0.7‐fold. At concentrations below the CMC, all four surfactants increased NAA penetration by 1.1‐ to 1.3‐fold. Time‐course studies of NAA flux on addition of surfactant revealed that, where NAA flux always increased it did so slowly, but any decrease of flux occurred rapidly. Sorption of NAA by cuticular membranes decreased progressively with increased EO chain length at surfactant concentrations 2.5 × CMC. Below the CMC, surfactants had little or no effect on NAA sorption. Our data provide evidence that surfactants increase transcuticular penetration of NAA by increasing the diffusion coefficient and, hence, the mobility of NAA in the cuticle.