bluuebunny/crossref_metadata_2025 huggingface dataset:
Lethal disturbances in larval development of Neobellieria bullata caused by metyrapone derivatives
Authors: Darvas Béla , Bélai Iván , Fónagy Adrien , Kulcsár Péter , Tag El‐Din Mahmoud H.
Published: November 2006

Larvae of Neobellieria bullata (Parker) were reared from hatching on a diet containing metyrapone derivatives. Metyrapone, A‐phenyl‐B‐imidazolylmetyrapone (PIM) and A‐phenyl‐B‐triazolyl metyrapone (PTM) inhibited the first moult of N. bullata. The larvae died within two days during an extended 1st instar. PIM and PTM caused malformation of anterior and posterior spiracles, and mandibles of larvae. PIM was more active than metyrapone, PTM or piperonyl butoxide.
Herbicidal activity of derivatives of 9‐aminofluoren‐9‐ylphosphonic acid
Authors: Wojtasek Hubert , Wieczorek Piotr , Lejczak Barbara , Boduszek Bogdan , Gancarz Roman , Kafarski Pawel
Published: November 2006

A series of derivatives of 9‐aminofluoren‐9‐ylphosphonic acid (phosphonic analogues of morphactins) were synthesized and screened for herbicidal activity against Lepidium sativum, Cucumis sativus and Lycopersicon esculentum. Ethyl 9‐(N‐alkylamino)fluoren‐9‐yl(phenyl)phosphinates appeared to be equipotent with glyphosate and thus may be recognized as new lead compounds for further structural modifications.
Toxicity, retention and distribution of [14c]hexaflumuron in the last larval instar of Leptinotarsa decemlineata, Spodoptera littoralis and Spodoptera exigua
Authors: Auda Mahroussa , El Saidy M. Fekry , Degheele Danny
Published: November 2006

The toxicity of the benzoylphenylurea hexaflumuron to newly ecdysed last‐instar larvae of Leptinotarsa decemlineata, Spodoptera littoralis and Spodoptera exigua was determined, together with the rate of retention and distribution of hexaflumuron during a 72‐h period. The results of the latter were considered in connection with the toxicity of this compound. Hexaflumuron was 54 and 19 times more toxic to L. decemlineata and S. littoralis respectively than to S. exigua. The amount of radioactivity, expressed as [14C]hexaflumuron retained in the larval body of L. decemlineata was high compared to that in the two other insect species. After 72h, >90% of ingested [14C]hexaflumuron was excreted by last‐instar larval S. littoralis and S. exigua, compared with 76% excreted by L. decemlineata larvae. The amount of radiolabelled residues recovered from the different tissues of L. decemlineata was more than five times greater than that recovered from S. littoralis and S. exigua after 24 h. This difference substantially increased after 48 and 72 h, reflecting a faster excretion, especially in S. exigua. These results suggest that the greater toxicity of hexaflumuron towards L. decemlineata is probably due to a greater retention of hexaflumuron in the larvae. Similarly, the greater toxicity of hexaflumuron towards S. littoralis compared with S. exigua larvae may result from a greater retention of pesticide in the former species.
Effects of certain herbicides on the fate of sporangiospores of Mucor piriformis and conidia of Botrytis cinerea and Penicillium expansum
Authors: Michailides Themis J. , Spotts Robert A.
Published: November 2006

The effects of several herbicides used in pome fruit orchards on the germination of spores and growth of mycelia of Botrytis cinerea, Mucor piriformis and Penicillium expansum in vitro and the survival of propagules of these fungi in soil were studied. Diuron in agar at 4–128 μg ml−1 reduced germination of spores of B. cinerea and M. piriformis, and 2,4‐D and paraquat at 32 μg ml−1 similarly affected B. cinerea and P. expansum. Several herbicides at 128 μg ml−1 in agar reduced growth of B. cinerea and M. piriformis but were ineffective against P. expansum. Propagule survival levels of the three fungi generally were lower in both autoclaved and non‐autoclaved soil amended with herbicides than in non‐amended soil. This effect was greatest in non‐autoclaved soil, suggesting involvement of microbial antagonists. The most effective herbicides for reduction of fungal propagules in soil were 2,4‐D, diuron, and paraquat.
Permethrin treatments in canadian forests. Part 3: Environmental fate and distribution in streams
Authors: Kreutzweiser David P. , Wood Glen A.
Published: November 2006

Aerial applications of permethrin at 17.5 g ha−1 resulted in maximum concentrations of 0.07–2.50 μg litre−1 in stream water. The median maximum concentration was 0.54 μg litre−1 in oversprayed streams (n = 35, mean = 0.66) and 0.25 μg litre−1 1–1.4 km downstream of treated areas (n = 11, mean=0.33). Permethrin residues in stream water declined with time and distance, with a mean disappearance rate of 0.106 h−1 and mean half‐life of 10.3 h at oversprayed sites, and a mean disappearance rate of 0.202 h−1 and half‐life of 3.9 h at downstream sites. Less than 8% of sediment samples from treated streams contained detectable permethrin concentrutions ( > 5 ng g−1). Approximately 50% of fish from streams in treated areas contained measurable residues ( > 5 ng g−1) up to 28 days post‐treatment. No residues were detected in fish at 69 or 73 days after the applications. In fish that contained measurable residues, the median bioconcentration factor was 98 (mean = 148).
Aldicarb residue degradation rates at three depths of a Wisconsin central sand plain aquifer
Authors: Kraft George J. , Helmke Philip A.
Published: November 2006

First‐order oxidation and hydrolysis rate constants for aldicarb sulfoxide and aldicarb sulfone were measured in laboratory studies representing three depths of a Wisconsin central sand plain aquifer with aerobic groundwater at pH 7‐6. Aldicarb sulfoxide or aldicarb sulfone were added to incubations containing sediment and groundwater from 0‐5, 5‐0, and 10‐0 m below the water table, and their concentrations followed with time. Rate constants were similar for all three depths, averaging 0‐0018, 0‐0004, and 0‐0029 day−1for aldicarb sulfoxide hydrolysis, aldicarb sulfoxide oxidation and aldicarb sulfone hydrolysis, respectively. Hydrolysis values were close to those of abiotic aqueous systems, indicating chemical and biological catalysis were minimal. Assuming typical initial total aldicarb sulfoxide and aldicarb sulfone concentrations in groundwater were 100 μg liter−1beneath treated fields and groundwater velocity was 0‐5 m day−1, 1000 days and 500 m groundwater travel distance would be required for residue levels to attain the Wisconsin regulatory standard of 10 μg liter−1at the studied location.
Acaricidal potential of piquerols A and B against Boophilus microplus
Authors: la Parra Mario Gonzalez‐de , Chavez‐Peña Daniel , Jimenez‐Estrada Manuel , Ramos‐Mundo Carlos
Published: November 2006

Bioassays with aqueous solutions of the natural compounds, piquerols A and B, at concentrations of 300 μg ml−1 were carried out on larvae and gravid female ticks of Boophilus microplus. Piquerols A and B were both found to have acaricidal potential on larvae. However, neither compound prevented oviposition. Piquerol A was observed to cause significant mortality in gravid female ticks.
Method for the determination of butachlor residues in water, soil and rice
Authors: Liu Weiping , Xu Huiqing , Chen Ziwen
Published: November 2006

A method is described for the analysis of water, soil and crops for residues of the herbicide butachlor. Residues were extracted with acetone + light petroleum distillate. The extracts were concentrated and purified on a chromatographic column containing aluminum oxide, silver–aluminum oxide and Florisil. Finally, they were quantitated by gas chromatography using an electron‐capture detector. The detection limits of various samples were between 0.001 and 0.015 mg kg−1. The average recoveries ranged from 79.4 to 104.6%.
Development of an atom mapping procedure for similarity searching in databases of three‐dimensional chemical structures
Authors: Pepperrell Catherine A. , Poirrette Andrew R. , Willett Peter , Taylor Robin
Published: November 2006

This paper discusses a procedure for calculating the degree of similarity between an input target molecule and each of the molecules in a database of 3D chemical structures. A mapping procedure is used to identify pairs of atoms, one from each of the molecules that are being compared, that lie at the centre of topographically similar volumes of 3D space. Experiments are reported to validate the significance of the similarities that result from the use of the procedure and to determine the effect on the calculated similarities of the structural representation that is used to characterise the molecules in a database.
Different in‐planta and ex‐planta activities of 7‐chloro‐4‐(2‐[trifluoromethyl]phenoxy)quinoline against Pyricularia grisea due to volatilization
Authors: Schneegurt Mark A. , Waldron Clive
Published: November 2006

7‐Chloro‐4‐[2‐(trifluoromethyl)phenoxy]quinoline (L Y248908) strongly inhibits mycelial growth of Pyricularia grisea in ex‐planta assays but, when applied to the foliage of rice seedlings, its protective and curative properties against P. grisea are poor. The principal cause for this difference was found to be volatilization of LY248908 from treated foliage. Variations in fungal sensitivity (due to strain or development stage) and compound loss due to translocation, sequestration, metabolism, or degradation were shown not to be significant.
Interception and persistence of parathion and fenvalerate on cotton plants as a function of application method
Authors: McDowell Leslie L. , Willis Guye H. , Southwick Lloyd M. , Smith Sammie
Published: November 2006

Parathion (O,O‐diethyl O‐4‐nitrophenyl phosphorothioate) and fenvalerate [(RS)‐α‐cyano‐3‐phenoxybenzyl (RS)‐2‐(4‐chlorophenyl)‐3‐methylbutyrate] were applied by controlled droplet applicators (CDAs) and conventional hydraulic nozzles in refined soybean oil, soybean oil + water, or water, to mature cotton plants (Gossypium hirsutum L.) as ULV (ultra‐low volume, < 5 litre ha−1), VLV(very low volume, 5‐50 litre ha−1), or LV(low volume, 50–200 litre ha−1) carrier rates. The use of CDA or soybean oil applied as ULV and VLV sprays did not produce greater deposition or persistence for either insecticide during the 49‐h test period following application. In general, insecticide persistence was greatest when applied with water or soybean oil + water as LV sprays using the conventional TX8 hydraulic nozzle.
Sorption of lonisable organic compounds by field soils. Part 2: Cations, bases and zwitterions
Authors: Nicholls Peter H. , Evans Avis A.
Published: November 2006

Sorption of a range of permanent cations, bases and zwitterionic compounds was measured as a function of pH in two soil types. Pyridinium cations were more strongly sorbed (Kd 10– > 1000) than aliphatic cations (Kd < 5). At very low pH, sorption of the aliphatic cations sharply decreased, probably because they are displaced by protons. Most weak bases, including carbendazim andpyridines, were strongly sorbed (Kd 9–35) at low pH, where they would be appreciably protonated, sorption becoming much weaker at soil pH values > 6. However, an additional mechanism of sorption was observed for those zwitterions capable of chelation (e.g. picolinic acid and alanine) which gave rise to high Kd values at pH values near neutral. Inorganic phosphate was strongly sorbed (Kd > 140) save at very low pff. Glyphosate and inorganic phosphate were sorbed very strongly at pH values near to 4 (Kd > 200). The very strong sorption was attributed to ligand exchange interaction. Sorption of picolinic acid was similar when measured in water or calcium chloride solution (0.01 M). However, sorption decreased with increasing concentration of calcium chloride up to 1 M, probably because the protonated form of picolinic acid was displaced by calcium ions.
DDT‐membrane interactions studied with two fluorescent probes
Authors: Antunes‐Madeira Maria Do Carmo , Almeida Leonor M. , Madeira Vitor M. C.
Published: November 2006

The effects of DDT (0‐100 μM) in pure phospholipid and phospholipid/cholesterol bilayers were investigated by fluorescence polarization of 1,6‐diphenyl‐1,3,5‐hexatriene (DPH), a probe located in the bilayer interior, and by excimer to monomer fluorescence intensity ratio (I′/I) of 1,3‐di(l‐pyrenyl)propane (Py(3)Py), a probe sitting closer to the polar region. In the gel phase of dimyristoylphosphatidylcholine (DMPC) bilayers, DDT induces concentration‐dependent fluidizing effects into the hydrophobic membrane regions, but no effects are observed in the outer regions of the membrane, as evaluated by DPH and Py(3)Py, respectively. Furthermore, in the fluid phase of DMPC and for DDT concentrations higher than 10 μM, I′/I of Py(3)Py decreases, reflecting an order increase of the probe environment and DPH fails to detect any apparent effect. Similar effects were observed in other pure lipid bilayers, namely dipalmitoylphosphatidylcholine (DPPC) and distearoylphosphatidylcholine (DSPC). Unlike DPH, Py(3)Py is very sensitive to DPPC and DSPC pre‐transitions which are not abolished by 50 μM DDT. This DDT concentration inhibits to some extent the cholesterol‐induced ordering in DMPC bilayers and high cholesterol concentrations (⩾ 30 mol%) do not prevent insecticide interaction, as evaluated by DPH. On the other hand, the effects of DDT reported by Py(3)Py depend on temperature and cholesterol content of DMPC bilayers. Thus, for cholesterol levels ranging from 10 to 50 mol% and for temperatures below the phase transition temperature of DMPC, Py(3)Py fails to detect any significant effect. Nevertheless, above the phase transition temperature of DMPC, Py(3)Py detects either ordering effects of DDT at low cholesterol contents (< 20 mol%) or fluidizing DDT effects at high cholesterol levels (> 20 mol%).
Mechanisms controlling leaf retention of agricultural spray solutions
Authors: Wirth Wolfgang , Storp Siegfried , Jacobsen Wolfgang
Published: November 2006

Active ingredient deposition as a whole during foliar spray application was studied by means of microscopic and macroscopic methods. High‐speed photography of the impact of spray droplets showed that rebound from reflective plant surfaces was reduced only with surfactant concentrations well above the critical micelle concentration. These results correlate with laboratory spraying experiments to determine quantitatively the retention of spray solutions. The dynamic interaction between droplet and foliage seemed to be specifically dependent on surfactant structure, concentration and the distribution of isomers or by‐products in the technical product. Rough surfaces with epicuticular wax crystals were difficult to wet; the orientation of the leaf, however, had little influence on retention. Apolar artificial surfaces retained water rather well and are therefore unsuitable as model surfaces for reflective leaves. Measurement of dynamic surface tension at 100 msec gave a satisfactory correlation with retention values in the case of liquids containing surfactant but failed to predict the good adhesion of polyvinyl alcohol solutions.
Mode of action studies with mefenacet
Authors: Fedtke Carl
Published: November 2006

The unicellular green alga Chlamydomonas reinhardtii was used as a model organism in studies of the mode of action of the oxyacetamide herbicide mefenacet. An algal strain with a decreased sensitivity towards mefenacet was obtained by successively increasing the herbicide concentration in the culture medium from 10 to 50 μM over 9 weeks. Similarly, a second strain was adapted to 10 μM metazachlor and a third one to 20 μM metolachlor. The resistance patterns of these three strains were studied with a selection of herbicides representing different modes of action. In the mefenacet‐ and metolachlor‐adapted strains, clear cross‐resistance was only obtained between the oxyacetamide mefenacet and the chloroacetanilides alachlor, butachlor, metazachlor and metolachlor. The resistance factors (I50 in resistant/I50 in sensitive algae) were between 4 and 50. Little or no resistance was obtained when herbicides with other modes of action were studied (resistance factors between 0.5 and 4). The situation was less clear in the metazachlor‐adapted strain, but here also strong cross‐resistance was seen with other chloroacetanilides and mefenacet (resistance factors between 25 and 40). This strain was, however, significantly cross‐resistant to some herbicides with other modes of action.

Investigations of the possible resistance mechanism in the mefenacet‐adapted strain have shown that neither uptake nor metabolism can explain the observed resistance behaviour. The lipid composition and the pattern of soluble amino acids were unchanged. It is concluded that oxyacetamides and chloroacetanilides have the same site of herbicidal action.
Inhibition of acetyl‐coenzyme a carboxylase by the novel grass‐selective herbicide 3‐(2,4‐dichlorophenyl)‐perhydroindolizine‐2,4‐dione
Authors: Babczinski Peter , Fischer Reiner
Published: November 2006

The novel herbicidal compound 3‐(2,4‐dichlorophenyl)‐perhydroindolizine‐2,4‐dione which is active as a pre‐ and post‐emergence grass‐selective herbicide is a new type of inhibitor of plant acetyl‐coenzyme A carboxylase (ACCase; E.C. 6.4.1.2). This has been demonstrated by in‐vitro experiments using isolated corn enzyme. Besides an I50 value of 4.7 μM under the assay conditions used, a mixed‐type inhibitory activity on the enzyme is established. The compound is inactive on rat liver A CCase enzyme and shows decreased activity (pI50 less than 3.0) on the spinach enzyme.
Quantitative structure—activity relationships of light‐dependent herbicidal 4‐pyridone‐3‐carboxanilides I. Effect of benzene ring substituents at the anilide moiety
Authors: Osabe Hirokazu , Morishima Yasuo , Goto Yukihisa , Masamoto Kazuhisa , Nakagawa Yoshiaki , Fujita Toshio
Published: November 2006

A number of substituted 4‐pyridone‐3‐carboxanilide derivatives show various degrees of light‐dependent herbicidal activity. The effects of substituents at the anilide moiety on the activity against Echinochloa oryzicola were analysed quantitatively with physicochemical substituent parameters. The activity was shown to vary parabolically with total hydrophobicity (Σπ) of the anilide ring substituents as well as with the steric parameter (Es) of the ortho‐substituents. The Es parameter for only the bulkier ortho‐substituent, with the more negative value, but not for the two, was significant. The effect of substituents at the 1‐position was expressible by indicator variables assigned to each 1‐substituted series, the physicochemical rationalization being left for future analyses.
Effects of metaldehyde and acetaldehyde on specific membrane currents in neurones of the pond snail Lymnaea stagnalis
Authors: Mills Janette D. , McCrohan Catherine R. , Bailey Stuart E. R.
Published: November 2006

Bath application of metaldehyde or acetaldehyde led to tonic depolarization and bursting activity in identified neurones in the isolated central nervous system of Lymnaea stagnalis. This activity was sometimes accompanied by paroxysmal depolarizing shifts in membrane potential. Those neurones which possessed type 2 action potentials showed marked spike broadening in response to metaldehyde, but little increase in action potential duration in the presence of acetaldehyde. Under voltage clamp, metaldehyde caused a reduction in the delayed rectifier and A‐currents, both of which are outward potassium currents. Acetaldehyde also reduced the delayed rectifier but had no effect on the A‐current. In type 2 neurones, voltage‐dependent calcium current appeared to increase in the presence of metaldehyde, but was decreased by acetaldehyde. The action of metaldehyde and acetaldehyde on firing activity, as well as their differential effects on action potential duration, may be partly explained by alterations in these specific membrane currents.
Diflubenzuron and oogenesis in the codling moth, Cydia pomonella (L.)
Authors: Soltani Noureddine , Soltani‐Mazouni Nadia
Published: November 2006

Diflubenzuron, topically applied (0·5 μg insect−‐1) to Cydia pomonella (L.) at pupal ecdysis disturbed growth and development of oocytes. It delayed the adult ecdysis and caused a decrease in both thickness of the follicular epithelium and the size of the basal oocyte during the pupal development. On the other hand, the size of basal oocytes, the protein content per ovary and the number of oocytes per ovary recorded in newly emerged adults were significantly reduced after diflubenzuron treatment.

These results, together with observations in several other species, indicate that the reduction in fecundity and egg viability is probably due to interference of diflubenzuron with the vitellogenesis process.
Insect growth regulating activity of 1,5‐disubstituted imidazoles against Bombyx mori and Oncopeltus fasciatus
Authors: Kuwano Eiichi , Hisano Tomomi , Eto Morifusa , Suzuki Koichi , Unnithan Gopalan C. , Bowers William S.
Published: November 2006

Seventeen 1,5‐disubstituted imidazoles possessing a variety of substituents were tested on Bombyx mori and Oncopeltus fasciatus. All compounds induced precocious metamorphosis from 4th‐instar larvae of B. mori. Of the compounds tested, 1‐benzyl‐5‐[(E)‐2,6‐dimethyl‐1,5‐heptadienyl]imidazole (KK‐42) was the most active against B. mori larvae. However, none of the compounds induced precocious metamorphosis in O. fasciatus nymphs, although several showed delayed toxicity. Treated nymphs died during or immediately after the moult. A series of 1‐isobutylimidazoles exhibited high activity against O. fasciatus, whereas KK‐42 was inactive even at high doses. There was no apparent correlation between the ability of imidazoles to cause precocious metamorphosis in B. mori and the delayed toxicity for O. fasciatus.
Time‐dependent changes in protein phosphorylation patterns in rat brain synaptosomes caused by deltamethrin
Authors: Kanemoto Yoshiro , Enan Essam E. , Matsumura Fumio , Miyazawa Mitsuo
Published: November 2006

Effects of deltamethrin, a powerful pyrethroid insecticide, on the protein phosphorylation and dephosphorylation processes during depolarization in rat brain synaptosomes were studied by using [32P]phosphoric acid as a starting radiotracer and high external concentration of potassium ions or veratridine (10−‐5M) as depolarizing agents. At the onset of depolarization there was a quick rise in phosphorylation in various synaptic proteins for about 15–30 s followed by a gradual decline in levels of phosphorylation. The effect of deltamethrin (10−‐7M) on this system was found to be dependent on the length of preincubation of the synaptosome with the pesticide prior to depolarization. At an early stage (0–3 min preincubation period) it caused a modest suppression of protein phosphorylation activities. When the period of deltamethrin preincubation was extended to 5–20 min, however, it caused a significant increase in protein phosphorylation throughout the depolarization period. At the later stage of the action of deltamethrin (e.g. preincubation period of 30–40 min), deltamethrin‐treated synaptosomes no longer responded to the depolarization signal to raise the level of phosphorylation on many proteins. These results indicate that deltamethrin's actions on the synaptic process are complex. Depending on the length of exposure, its effects on protein phosphorylation responses in intact synaptosomes could be either stimulatory or inhibitory. To study the cause of deltamethrin‐induced synaptic block at the later stage, effects of deltamethrin on protein kinases were studied by using lysed synaptic membranes with [gamma‐32P]ATP. Deltamethrin was shown to inhibit calcium–calmodulin‐dependent protein phosphorylation activities at 10−‐7M when given directly to the enzyme source 10 min prior to the addition of [32P]ATP. Such an observation helps to explain the inhibitory action of deltamethrin on protein phosphorylation which occurs at the late stage of its action (i.e. preincubation time > 20 min).
Insecticide resistance in Helicoverpa armigera in South India
Authors: Armes Nigel J. , Jadhav Deepak R. , Bond Gerald S. , King Andrew B. S.
Published: November 2006

Cypermethrin, quinalphos, endosulfan and methomyl were bioassayed against strains of Helicoverpa armigera collected from field crops in Andhra Pradesh and Tamil Nadu, South India, during the 1989‐90 and 1990‐91 cropping seasons. In 1989, high levels of resistance to cypermethrin were recorded in strains from cotton in the cotton‐growing regions of Guntur, Andhra Pradesh and Coimbatore, Tamil Nadu, and from pigeon pea near Hyderabad. There was no evidence for resistance to quinalphos or methomyl at that time. In 1990‐91 sampling was more extensive and although tolerance to cypermethrin was lower than the previous season, the survey indicated that pyrethroid‐resistant populations were present throughout much of Andhra Pradesh. Tolerance to quinalphos had increased slightly in 1990‐91, while resistance to methomyl had increased substantially, particularly in the cotton‐growing area of Guntur. Endosulfan tolerance had increased slightly compared to strains tested in 1986‐88 in an earlier study. The geographic and temporal variations in severity of pyrethroid resistance in H. armigera in Andhra Pradesh are believed to arise because of dynamic interactions between local selection pressure and immigration of resistant and susceptible moths at certain times of the year.
Leaching of atrazine into ground water
Authors: Felding Gitte
Published: November 2006

A study of the leaching of atrazine from soils in Denmark with high hydraulic conductivity demonstrated only small quantities of the herbicide in the upper ground‐water zone. The atrazine‐treated fields were situated in a region where the water table was high and free lying and where the cover layer consisted of sand. Samples were taken from the upper 1–5 m ground‐water zone at three well‐defined levels. The atrazine content was between 0.01 and 0.05 μg litre−1 the highest concentrations being found at the top of the ground‐water zone.
Negative cross‐resistance to bentazone and pyridate in atrazine‐resistant Amaranthus cruentus and Amaranthus hybridus biotypes
Authors: De Prado Rafael , Sanchez Manuel , Jorrin Jesus , Dominguez Carmen
Published: November 2006

Plants of Amaranthus cruentus and Amaranthus hybridus resistant to atrazine and cyanazine were found in maize fields in north‐eastern Spain. Both resistant foiotypes survived doses of 5 kg ha−1 of atrazine and 2–4 kg ha−1 of cyanazine but were controlled by lower doses of bentazone and pyridate than were susceptible biotypes. Such a negative cross‐resistance was not found for chloroacetamides and MCPA. Chlorophyll fluorescence studies revealed that atrazine, bentazone, cyanazine and pyridate (10 mg litre−1) caused inhibition of photosynlhetic electron transport in susceptible leaves, while in resistant plants, atrazine and cyanazine had no effect. Conversely, bentazone and pyridate inhibited photosynthesis to a greater extent in resistant than in susceptible biotypes. Isolated chloroplast membranes from resistant biotypes showed resistance factors of 366 and 501 to atrazine and 39 and 60 to cyanazine for A. hybridus and A. cruentus, respectively. Bentazone and pyridate were found to be more effective in chloropiasts of the resistant biotypes than those of the susceptible plants. It is suggested that enhanced susceptibility to bentazone and pyridate in triazine‐resistant A. cruentus and A. hybridus biotypes may be associated with the alteration of the D‐I polypeptide subunit of photosystem II, as found in triazine‐resistant plants.
Heterotrophic plant cell suspension cultures for monitoring biological activity in agrochemical research. Comparison with screens using algae, germinating seeds and whole plants
Authors: Grossmann Klaus , Berghaus Rainer , Retzlaff Günter
Published: November 2006

Heterotrophically cultured cell suspensions are used increasingly in agrochemical research for screening plant‐growth retardants and herbicides which influence plant meristems. For this purpose, a large‐scale microscreen has been devised, which permits the objective monitoring of cell division by measuring the conductivity in cell suspensions cultured in test tubes. Comparing the effects of a wide spectrum of growth retardants and herbicides with different primary modes of action, the test was most sensitive to nitrogen‐geterocyclic retardants in wheat‐cell suspensions and to sulfonylurea > imidazolinone > cyclohexanedione, oxy‐phenoxypropionic acid, nitrile > glufosinate, phenoxy acid, bipyridylium and diphenyl ether herbicides in maize and oilseed rape cell cultures. As had been expected, inhibitors of photosynthetic processes were only slightly active. The results of the tests were compared with the effects of the compounds on germinating seeds of cress (Lepidium sativum L.) and on photoautotrophic systems using algal cell suspensions (Scenedesmus acutus) and duckweeds (Lemna paucicostata). It is suggested that heterotrophic cell suspensions, in combination with the series of biotests mentioned above, are a valuable complement to the whole‐plant screens used routinely in industrial laboratories. They are particularly useful for identifying compounds whose biological activity is masked by limited penetration or translocation behaviour in whole plants.
Pharmacokinetics and in‐vivo Metabolism of Gamma‐Hexachlorocyclohexane in a Susceptible Strain of the Egyptian Cotton Leafworm, Spodoptera littoralis (Boisd.)
Authors: Lagadic Laurent , Dubroca Jacqueline , Echaubard Michel
Published: November 2006

The fate of gamma‐HCH (hexachlorocyclohexane) was studied in a susceptible strain of the Egyptian cotton leafworm, Spodoptera littoralis (Boisd.). A non‐lethal dose (0·2 μg larva−1) was topically applied to fourth‐instar larvae, and the pharmacokinetics of the insecticide were studied for a period of 48 h following treatment. Penetration showed biphasic kinetics, with a rapid increase of the internal gamma‐HCH concentration during the first 6 h after the application, followed by a plateau up to 48 h. The rate of metabolic degradation was highest between 6 and 24 h. During this period, the rapid decrease in the amount of gamma‐HCH in the larvae was associated with an accelerated excretion of metabolites. A compartmental model with curve‐fitting was used to quantify the rates of uptake through the cuticle (penetration) and of loss from the tissues (degradation and elimination). Chromatographic analysis of the aqueous and organic fractions extracted from the larvae and their faeces provided direct evidence that our susceptible strain of S. littoralis was able to metabolise a nonlethal dose of gamma‐HCH.
Substrate‐Dependent Bioavailability of Deltamethrin for the Epigeal Spider Oedothorax apicatus (Blackwall) (Aranaea, Erigonidae)
Authors: Op Akkerhuis Gerard A. J. M. Jagers , Hamers Timo H. M.
Published: November 2006

Terrestrial arthropods are mainly exposed to pesticides by uptake from the substrate e.g. “residual” uptake, which depends on the bioavailability of the pesticide. The residual uptake of deltamethrin by female Oedothorax apicatus (Blackwall), a linyphiid spider, was studied in relation to dependence on soil cover, soil moisture, walking behaviour, time after spraying and deposition rate. C14‐labelled deltamethrin was used to quantify the uptake processes. Data were analysed using multiple regression analysis.

Uptake was markedly higher from soil covered with fungi or moss than from uncovered soil. From uncovered soils with moisture contents varying from 7 to 49% dry weight, low uptake was measured, while at 63% moisture, the uptake was high. The bioavailability half‐life was 157 min. The rate of uptake decreased with distance walked. The possible consequences of these results for field experiments are discussed.
Long‐term effects of insecticides on diaeretiella rapae (m'intosh), a parasite of the cabbage aphid
Authors: El‐Ghar Gamal E. S. Abo , El‐Sayed Abd
Published: November 2006

Five insecticides were tested in the laboratory for their selective activities between the cabbage aphid, Brevicoryne brassicae (L.), and its associated parasitoid, Diaeretiella rapae (M'Intosh). Based on the concentration/mortality regressions, the synthetic pyrethroids tralomethrin and cypermethrin were the most active insecticides against both the cabbage aphid and the parasitoids within the mummified aphids, whereas the carbamate methomyl was the least active. Selectivity ratios, at LC50, for B. brassicae vs. D. rapae in the mummified aphids showed that all insecticides tested were more active against B. brassicae than against the parasitoids. All insecticides used at the recommended field rates reduced the emergence of adult parasitoids from mummified aphids by 55–97% of that of control. Survival and longevity of emerged D. rapae were significantly reduced by all insecticides and rates used.

Consequently, the latent effects of these insecticides applied at and below the recommended field rates were estimated on the parasitoids through two successive generations. The recommended rates used for both methomyl and cypermethrin reduced fecundity of D. rapae recorded at the F1‐generation by 75% of that of control. The emergence of F1‐progeny D. rapae was not significantly affected in any treatment, whereas the survival and longevity of adult parasitoids were reduced by most treatments.

At the F2‐generation, the fecundity of parasitoid females was still lower than in the untreated control. Emergence and survival of adult parasitoids seemed to be slightly affected, whereas the adult longevity was highly affected in all treatments.

Methomyl, tralomethrin and cypermethrin might be preferred because they had minimal adverse effects on emergence of parasitoids from the mummified aphids and their subsequent survival, longevity and fecundity, when applied at rates little below the recommended field rates.
Cytochrome P‐450 Inducers and Inhibitors Interfering with Ecdysone 20‐Monooxygenases and Their Activities during Postembryonic Development of Neobellieria bullata Parker
Authors: Darvas Béla , Rees Huw H. , Hoggard Nigel , El‐Din Mahmoud H. Tag , Kuwano Eiichi , Bélai Iván , Timár Tibor
Published: November 2006

The cytochrome P‐450‐dependent microsomal and mitochondrial ecdysone 20‐monooxygenase systems convert ecdysone into 20‐hydroxyecdysone. The microsomal fraction of fat bodies of zero h wandering stage fleshfly larvae (Neobellieria bullata; Diptera: Sarcophagidae) has a high ecdysone 20‐ monooxygenase activity. The effects of cytochrome P‐450 inhibitors were investigated in vitro on microsomal ecdysone 20‐monooxygenase. Metyrapone, fenarimol and certain imidazole derivatives (KK‐42, KK‐110, KK‐135 and PIM) are strong inhibitors. The IC50 value of KK‐110, which is the strongest inhibitor, is 2 × 10−7 M. A triazolyl and two cyclopropylamine derivatives have low activity. The activities of different NADPH‐cytochrome c (P‐450) reductase inhibitors were also assessed; diquat dibromide is a moderate inhibitor of microsomal ecdysone 20‐monooxygenase, while paraquat dichloride has no activity.

In‐vivo experiments with cytochrome P‐450 inducers and inhibitors gave the following results: (a) fenarimol, FI‐121, precocene‐2 caused “permanent” first‐instar larvae; (b) barbital, phenobarbital and their sodium salts caused significant delay in larval development; (c) PIM, PTM, metyrapone, KK‐42, KK‐135, J‐2710, RH 5849 and colchicine caused moulting disturbances; (d) J‐2710, PIM, PTM, KK‐42, KK‐135, RH 5849 and colchicine caused lethal spiracle and mandible malformation; (e) KK‐110, fenarimol, barbital and phenobarbital caused precocious pupariation.
QSAR and Expert Systems in the Prediction of Biological Activity
Authors: Judson Philip N.
Published: November 2006

Traditional quantitative structure‐activity relationship (QSAR) approaches and expert system approaches to the prediction of biological activity on the basis of chemical structure have concentrated on different aspects of the problem. The key aim of QSAR studies has been to create models that can predict activity–in a sense, to discover the rules that govern the relationships between the presence of structural features and biological activity. Expert systems developed in recent years, on the other hand, seek to apply rules that encompass existing human knowledge about the links between key, complex structural features and particular toxicological end‐points. It is now becoming possible to provide automated help with the discovery of rules that are suitable for use in the knowledge‐based expert systems. Some examples of this are discussed.
Effects of Ampropylfos (RS)‐1‐aminopropylphosphonic acid) on zoospore formation, repeated zoospore emergence and oospore formation in Aphanomyces spp.
Authors: Cerenius Lage , Rufelt Snorre , Söderhäll Kenneth
Published: November 2006

The effects on growth, asexual and sexual reproduction of different Aphanomyces species by the new fungicide ampropylfos ((RS)‐1‐aminopropylphosphonic acid) were tested using highly synchronized cultures. Ampropylfos reduced mycelial growth in Aphanomyces astaci, A. euteiches and A. stellatus. The fungicide was found to reduce zoospore numbers in all Aphanomyces species tested except A. euteiches. In one species, A. stellatus, zoospore production was inhibited at much lower fungicide concentrations than in the other species tested. In the pea pathogen A. euteiches, ampropylfos reduced the number of oospores, whereas the fungicide had little effect on asexual reproduction.
Analysis of foliar uptake of pesticides in barley leaves: Role of epicuticular waxes and compartmentation
Authors: Schreiber Lukas , Schönherr Jörg
Published: November 2006

Uptake of pesticides into barley leaves was measured under controlled conditions. Leaves detached from plants were submerged in aqueous solutions of 14C‐labelled (2,4‐dichlorophenoxy)acetic acid, triadimenol, bitertanol and pentachlorophenol. Uptake was biphasic. A short (30‐min) period with high rates of uptake was followed by uptake that proceeded more slowly and was steady over hours. Compartmentation of pesticides was studied by desorbing pentachlorophenol from leaves previously loaded with [14C]pentachlorophenol. From the uptake and desorption kinetics it was concluded that penetration of pesticides proceeds as follows: the compounds are first sorbed at the surface of epicuticular wax aggregates where they are in contact with the donor solutions. Solutes then diffuse through the surface wax aggregates into the cuticle. Equilibrium between donor solutions, surface wax and cuticle is established in about 30 min. After this time the amounts of solutes in these compartments no longer increase. Uptake after this time represents penetration into the leaf cells. This fraction of the pentachlorophenol is retained irreversibly, while that sorbed in wax and cutin can be desorbed again. All compounds were sorbed in cuticular waxes and partition coefficients wax/water were determined. On a mass basis only 5 to 10% of the amounts sorbed in cutin are sorbed in wax. This comparatively low solubility in wax contributes to the barrier properties of cuticular waxes. The other determinant of permeability is the very low mobility of solutes in cuticular waxes.
Synthesis, structure and herbicidal activity of pyrazol‐4‐yl alkyl ketone derivatives
Authors: McFadden Helen G. , Huppatz John L. , Couzens Michelle , Kennard Colin H. L. , Lynch Daniel E.
Published: November 2006

Novel 5‐amino‐1‐phenylpyrazol‐4‐yl alkyl ketones were synthesised and their herbicidal properties evaluated. Active compounds in the series induced accumulation of protoporphyrin IX in etiolated cucumber cotyledons and caused light‐dependent herbicidal effects in 21‐day‐old cucumber plants. Structural features of the pyrazoles that contributed to herbicidal potency were found to be a high degree of halogen substitution in the 1‐phenyl ring, no substitution in the pyrazole 3‐position, and an ethyl group as the alkyl component of the ketone. The structure of 1‐[5‐amino‐1‐(2,4,6‐trichlorophenyl)pyrazol‐4‐yl]‐2‐methylpropan‐1‐one was determined by X‐ray crystallography.
Similarities in the antifungal activities of fenpiclonil, iprodione and tolclofos‐methyl against Botrytis cinerea and Fusarium nivale
Authors: Leroux Pierre , Lanen Catherine , Fritz René
Published: November 2006

Fenpiclonil [4‐(2,3‐dichlorophenyl)pyrrole‐3‐carbonitrile], a new agricultural fungicide, is a structural analogue of the antibiotic pyrrolnitrin used as an antimycotic in animals. Its spectrum of antifungal activity is similar to that of iprodione and tolclofos‐methyl, which are representatives of dicarboximide and aromatic hydrocarbon fungicides. Laboratory mutants of Botrytis cinerea and Fusarium nivale were simultaneously resistant to fenpiclonil, iprodione and tolclofos‐methyl and they showed an increased susceptibility to high osmotic pressure (sodium chloride, glucose). Strains of B. cinerea, collected in Champagne vineyards, which were resistant to dicarboximides were not resistant to fenpiclonil and tolclofos‐methyl. The antioxidant α‐tocopheryl acetate, and the cytochrome P‐450 inhibitors piperonyl butoxide and tebuconazole antagonized the fungitoxicity of fenpiclonil and iprodione in a wild‐type strain of B. cinerea. The uncoupling activity of fenpiclonil, iprodione and tolclofos‐methyl was detected in mitochondria from both a wild‐type strain and a laboratory mutant of B. cinerea. The concentrations effective towards this process were greater than those inhibiting the mycelial growth of wild‐type strains. These results suggest that fenpiclonil, iprodione, tolclofos‐methyl and related fungicides have the same biochemical mode of action. However, a primary effect on respiration, previously considered for pyrrolnitrin, seems to be improbable.
The susceptibility of a cereal aphid pest and its natural enemies to Deltamethrin
Authors: Wiles John A. , Jepson Paul C.
Published: November 2006

The intrinsic toxicity of deltamethrin to the grain aphid Sitobion avenae (F.) (Hemiptera: Aphididae) and a range of its important natural enemies was determined by laboratory topical bioassay. The natural enemies included polyphagous predators such as Pterostichus melanarius (Illiger), Harpalus rufipes (Degeer), Nebria brevicollis (F.), Agonum dorsale (Pont.), Demetrias atricapillus (L.), Trechus quadristriatus (Schrank), Bembidion obtusum (Serville), and B. lampros (Herbst.) (Coleoptera: Carabidae), Tachyporus hypnorum (F.) (Coleoptera: Staphylinidae) and Erigone atra (Blackwall) (Araneae: Linyphiidae), as well as the aphid‐specific ladybird Coccinella septempunctata (L.) (Coleoptera: Coccinellidae). Dose–response relationships were compared between species by probit analysis and maximum likelihood procedures to determine trends of susceptibility, measured in terms of ng a.i. arthropod−1 and μg a.i. g−1 body weight. The range of LD50 values varied between 0.8 and 232 ng arthropod−1 and 0.76 and 66.17 μg g−1 body weight for the species tested. The linyphiid spider E. atra (♀) was the most intrinsically susceptible species and had the narrowest tolerance distribution of the predators tested, whereas the small carabid beetle D. atricapillus was the least intrinsically susceptible predator species. There were significant differences in susceptibility between species of different orders, i.e. the Araneae, Hemiptera and Coleoptera. Differences within the Coleoptera were closely related to body weight, with the exception of the carabid beetle D. atricapillus, which seemed to be tolerant to deltamethrin. Knockdown time studies indicated that D. atricapillus had a higher survival rate after being knocked down than other species of predator. Aphid susceptibility per unit body weight was not significantly different from that of the predators. The aphid did, however, demonstrate a broader tolerance distribution than most of the predators, which may be related to its herbivorous nature. The use of laboratory susceptibility data to determine selectivity and to predict pesticide hazard is discussed.
Influence of organic matter and its clay complexes on metolachlor adsorption on soil
Authors: Pusino Alba , Liu Weiping , Gessa Carlo
Published: November 2006

The absorption of metolachlor, 2‐chloro‐6′‐ethyl‐N‐(2‐methoxy‐1‐methylethyl)acet‐o‐toluidide was studied on three soils of various physical and chemical properties. Adsorption isotherms conformed to the Freundlich equation. The kf values increased with increasing organic carbon content of the soils. However, variations in koc values by a factor of four were observed within three natural soils. For a given soil, the koc values remained essentially unchanged after lowering the carbon content by hydrogen peroxide oxidation. These results suggest that the contribution of organic matter to total metolachlor adsorption process is influenced by association mechanisms between organic and inorganic soil constituents. Studies with mixtures of clay and organic matter indicate that the interaction between the two soil components reduces the surfaces available for metolachlor adsorption.
Investigation of the possible vapour action of α‐endosulfan on Glossina morsitans morsitans
Authors: Smith Sandra C.
Published: November 2006

An all‐glass apparatus was set up whereby insects were brought into contact with α‐endosulfan vaporized from a heated bulb. The attribution of the initial high mortality to vapour action was not substantiated by subsequent chemical analysis. Use of reduced amounts of x‐endosulfan to provide more nearly the calculated saturated vapour concentration resulted in little kill. The α‐endosulfan vaporized transiently then condensed onto the surrounding surfaces; any mortality resulted from contact action. These observations do not support the contention that α‐endosulfan acts via the vapour phase at long range in the field.
Chemicals in integrated control
Authors: Oomen Pieter A.
Published: November 2006

The objective of Integrated Control (IC) is to provide economic and competitive cropping with as few undesirable effects of crop‐protection measures on the environment, the user or the consumer as possible. A general scheme of relevant variables, characteristics and their interrelationships is defined and those relations and aspects critical for realising the objective are identified. Particular attention is given to the function of pesticides and their adverse effects on beneficial organisms.

Chemical control is least preferred of all effective measures because of possible undesirable effects. Nevertheless, chemical and biological measures are very much complementary and there is no reason to expect a major change in this situation.

Apart from the general requirements for environmental, user and consumer safety, pesticides for use in IC schemes should be effective against target organisms but (largely) harmless to the beneficial organisms used in the biological measures, i.e. intrinsically selective or suitable for selective application. Because different profiles of pesticides are required to cover the needs of IC, the availability of a number of different pesticides and, especially, reliable information on their activity spectra is important.

The need for, and development of, a database covering all possible effective measures for crop protection which might fill this need in The Netherlands, as an aid to scientists developing schemes for integrated control and for extensionists advising growers, is presented as a solution to the main constraint identified for IC in protected and other crops.