bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrophysiological identification of site‐insensitive mechanisms in knockdown‐resistant strains (kdr, super‐kdr) of the housefly larva (Musca domestica)
Authors: Pepper David R. , Osborne Michael P.
Published: November 2006

The effects of pyrethroids were studied upon isolated segmental nerves and neuromuscular junctions in both susceptible (Cooper) and knockdown‐resistant (kdr; super‐kdr) strains of housefly larvae (Musca domestica L.). Isolated segmental nerves contained neither cell bodies nor synaptic contacts; thus, any effects of pyrethroids were attributed solely to their actions upon voltage‐dependent Na+ channels. Threshold concentrations of the type II pyrethroid, deltamethrin, required to elevate the spontaneous firing rate of these nerves were determined. Both resistant strains were about ten times less sensitive to deltamethrin than the susceptible strain, but insensitivity of super‐kdr nerves was no greater than in the less resistant kdr strain. At neuromuscular junctions, the minimum concentrations of pyrethroids needed to trigger massive increases in the frequency of miniature excitatory postsynaptic potentials (mEPSPs) were determined for deltamethrin and the type I pyrethroid, fenfluthrin. With fenfluthrin there was no detectable difference between the junctions of kdr and super‐kdr strains, which were both about ten‐fold less sensitive than Cooper junctions. With deltamethrin, kdr junctions were about 30 times less sensitive than those of Cooper; super‐kdr junctions were dramatically insensitive to deltamethrin, being some 10000‐ and 300‐fold less sensitive than those of Cooper and kdr respectively. Thus, in the synaptic assay, super‐kdr conferred an extension in resistance over kdr only against the type II pyrethroid, it being ineffective against fenfluthrin. We suggest that kdr resistance comprises at least two site‐insensitive areas within the nervous system. One involves insensitivity of the Na+ channel and has similar efficacy in both kdr and super‐kdr strains against type I and II pyrethroids; the other is associated with the presynaptic terminal and is particularly effective in super‐kdr resistance against type II pyrethroids. The latter could be associated with Ca2+‐activated phosphorylation of proteins involved with neurotransmitter release. Such phosphorylation reactions are known to be perturbed by pyrethroids, especially by type II compounds.
Effect of the acylurea insect growth regulator teflubenzuron on the endo‐larval stages of the hymenopteran parasitoids Cotesia plutellae and Diadegma semiclausum in a susceptible and an acylurea‐resistant strain of Plutella xylostella
Authors: Furlong Michael J. , Wright Denis J.
Published: November 2006

The toxicity of the acylurea, teflubenzuron, was assessed against larval stages of the hymenopteran parasitoids, Cotesia plutellae Kurdjumov and Diadegma semiclausum Hellén in a susceptible laboratory strain and a teflubenzuron‐resistant field strain of the diamondback moth, Plutella xylostella L. In fourth‐instar hosts (L4), when both parasitoid species were in their final larval instar, teflubenzuron significantly (P < 0.05) reduced emergence of adult D. semiclausum but had no significant (P > 0.05) effect on C. plutellae, although a small proportion of the latter were unable to reproduce. Treatment of L4 hosts with teflubenzuron ( > LD50) had no significant (P > 0.05) effect on the fecundity of surviving females of D. semiclausum. Similar differential toxicity with teflubenzuron was observed in L2 hosts, when parasitoids were at the egg or early larval instar stage. There was no apparent increased effect of teflubenzuron on either species of parasitoid when highly resistant (c. 4000‐fold) L2 hosts (field strain) were treated with concentrations of teflubenzuron two to three orders of magnitude greater than in equivalent experiments with the susceptible host strain. This suggests that host resistance to teflubenzuron confers some protection to both species of parasitoid. Uptake experiments with [14C]teflubenzuron showed that accumulation of radioactivity was much greater in D. semiclausum than in C. plutellae and this may account for the differential toxicity observed. The results are discussed in relation to the field status of these parasitoid species. The influence of insecticide resistance in the host on endo‐larval parasitoids is also considered.
The metabolism of fosetyl‐aluminium and the evolution of residue levels in oranges and tangerines
Authors: Pelegrí Rosa , Gamón Miguel , Coscollá Ramón , Beltrán Victoria , Cuñat Pascual
Published: November 2006

The metabolism of fosetyl‐aluminium to phosphonic acid in the peel of citrus fruit has been studied by gas chromatography using a nitrogen‐phosphorus detector and also with a flame photometric detector. At the same time the phosphonic acid residues remaining in the peel and the pulp of citrus fruit, as a result of the application of aqueous solutions of fosetyl‐aluminium at 2.5 g litre−1 to trees prior to harvest was determined.
Development of a cell‐free assay from Botrytis cinerea as a biochemical screen for sterol biosynthesis inhibitors
Authors: Stehmann Christiane , Kapteyn Johan C. , De Waard Maarten A.
Published: November 2006

An assay for measuring ergosterol synthesis in cell‐free extracts of the filamentous plant pathogen Botrytis cinerea is described. The extracts capable of synthesizing C4‐desmethyl sterols from [2‐ 14 C]mevalonate were derived by mechanical disruption of young conidial germlings in a Bead‐Beater apparatus. The C4‐desmethyl sterol fraction consisted of three distinct compounds and totalled 39% of the non‐saponifiable lipids formed. Ergosterol accounted for 63% of the C4‐desmethyl sterols. Only small amounts of C4‐monomethyl sterols were synthesized, while C4, 4‐dimethyl sterols made up 29% of the non‐saponifiable lipids. The latter fraction mainly consisted of lanosterol (54%) and eburicol (28%). The cell‐free system had a narrow pH optimum for synthesis of C4‐desmethyl sterols of pH 7.3–7.4. Cell‐free synthesis of C4‐desmethyl sterols was inhibited by the imidazole fungicide imazalil, concomitant with an accumulation of eburicol. The IC50 value (concentration of fungicide which inhibited cell‐free synthesis of C4‐desmethyl sterols by 50%) was 9.1 × 10 −9 M. These results are consistent with the hypothesis that imazalil is a potent inhibitor of the cytochrome P450‐dependent sterol 14x‐demethylase of B. cinerea. The method described may be used to screen compounds biochemically for inhibition of sterol synthesis in an agriculturally important plant pathogen.
Some Comments on a recently proposed method of determining chlormequat residues by derivatization with pentafluorothiophenol
Authors: Mortimer Richard D. , Weber Dorcas F.
Published: November 2006

A recent publication concerning the analysis of residues of the herbicide chlormequat in cotton seed by gas chromatography contains a significant error. A derivative prepared by reacting pentafluorothiophenol with chlormequat is actually produced by the reaction of the initial product of demethylation of chlormequat with a second molecule of pentafluorothiophenol. As the derivative is not derived from the chlormequat backbone, the method is not specific to chlormequat and could be misleading to an analyst using it or adapting it to other produce.
Piquerol a and diacetyl piquerol act as energy transfer inhibitors of photosynthesis
Authors: Mendoza José Luis , Jiménez Manuel , Lotina‐Hennsen Blas
Published: November 2006

ATP synthesis and phosphorylating (coupled) electron flow of freshly lysed pea chloroplasts were inhibited by piquerol A and diacetyl piquerol, the latter being more active. H + ‐uptake, basal and uncoupled electron transport were not affected by either compound, indicating that they act as inhibitors of photophosphorylation at the H + ‐ATPase complex.
Termite control with microencapsulated permethrin
Authors: Schoknecht Ute , Rudolph Dieter , Hertel Horst
Published: November 2006

Bait methods with microencapsulated active ingredients are proposed for controlling local populations of subterranean termites. The foraging workers will take up the microcapsules, transport them to the nest and pass them to their nestmates.

In laboratory tests microencapsulated formulations of permethrin had lethal effects on Heterotermes indicola Wasman and Reticulitermes flavipes (Kollar) depending on the amount of active ingredient applied. The time interval between the application of the capsules and the occurrence of insecticidal effects could be modified by changing the wall thickness of the capsules. Tests revealed that the microcapsules were transmitted from donors to recipients by trophallaxis. Microencapsulated formulations from which the solvent used during the manufacturing process had been removed did not reveal any repellent effects in several tests.
Plant‐growth‐regulating N‐(phosphonoacetyl)amines
Authors: Wieczorek Piotr , Miliszkiewicz Dorota , Lejczak Barbara , Soroka Miroslaw , Kafarski Pawel
Published: November 2006

A series of N‐(phosphonacetyl)amine derivatives were synthesized and screened for plant‐growth regulating activity on Lepidium sativum L. and Cucumis sativus L. Aromatic N‐(phosphonoacetyl)amines. which may be considered as possible analogues of N‐acylaniline herbicides obtained by replacement of their acyl group by the phosphonacetyl moiety, exhibited significant or moderate herbicidal activity. In contrast, N‐(phosphonoacetyl)amino acids and N‐(phosphonoacetyl)aminophosphonic acids promoted the growth of L. sativum and C. sativus roots.
Persistence of fenthion residues in olive oil
Authors: Lentza‐Rizos Chaido , Avramides Elizabeth J. , Roberts Rosemary A.
Published: November 2006

The level of fenthion residues was followed for up to one year in olive oil samples. The concentration of the parent compound decreased slowly following a double‐phase first‐order decay model, both in the freezer and laboratory, while the total concentration (parent compound and its sulfoxide) remained unchanged. Storage, therefore, cannot be used as a decontamination technique for oil containing higher than the toxicologically acceptable residues of this compound.
Kinetics and hydrolysis mechanism of chlorsulfuron and metsulfuron‐methyl
Authors: Hemmamda Saadi , Calmon Michelle , Calmon Jean P.
Published: November 2006

In acidic media, hydrolysis of chlorsulfuron and metsulfuron‐methyl occurs via two consecutive reactions which were followed by ultraviolet spectrophotometry. For these two reactions, the pseudo‐first‐order rate constants increase proportionally to the concentration of hydronium ion in the more acidic media and to the square of this concentration at higher pH values.

A kinetic study by HPLC shows that the first reaction leads to the formation of 4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐amine and (o‐chlorophenylsulfonyl) carbamic acid for chlorsulfuron or (o‐methoxycarbonylphenylsulfonyl) carbamic acid for metsulfuronmethyl. The second reaction is the conversion of these sulfonylcarbamic acids to sulfonamides and carbon dioxide. The complete lack of saccharin and of o‐sulfamoyl benzoic acid proves that the ester function of the methoxycarbonyl group is stable.

The lack of general acid‐base catalysis and a solvent deuterium isotope effect less than unity are consistent with a rate‐determining cleavage of the protonated substrate.

In the basic pH range (10–14) a single reaction occurs, the nucleophilic substitution of the methoxy group on the triazine by a hydroxide group.
Determination of organochlorine pesticide residues in river sediments by soxhlet extraction with hexane‐acetone
Authors: Tan Guan H. , Vijayaletchumy K.
Published: November 2006

Soxhlet extraction with hexane + acetone (1 + 1 by volume) was used for the extraction of organochlorine pesticide residues from river sediments, followed by Florisil column chromatography clean‐up and determination by gas chromatography with an electron‐capture detector. Average recoveries exceeding 90 % were obtained using this technique. Organochlorine pesticide residue levels in sediment samples from two major rivers flowing through predominantly rice‐growing areas were determined by this method. Relatively high residue levels of organochlorine pesticides such as HCH, heptachlor and endosulfan were found in the sediments.
Interference of the phenylpyrrole fungicide fenpiclonil with membranes and membrane function
Authors: Jespers Ad B. K. , Davidse Leen C. , De Waard Maarten A.
Published: November 2006

The phenylpyrrole fungicide fenpiclonil accumulates to high levels in mycelium of Fusarium sulphureum and artificial liposomes. The accumulation is a result of a physicochemical distribution of the fungicide over lipid‐like material of the mycelium and the medium. Accumulation is reversible, as the fungicide can easily be removed from the mycelium by washing with water. Fenpiclonil is not metabolized by the fungus during incubation for 24 h. The fungicide affects neither membrane fluidity in artificial liposomes nor amino acid accumulation in bacterial vesicles. Thus, accumulation of the fungicide does not seem to affect the functioning of membranes.

Fenpiclonil induces the accumulation of the membrane‐potential probe tetra‐phenylphosphonium bromide by F. sulphureum. Since accumulation of this probe probably reflects the cumulative potential over all cell membranes, the increased accumulation is more likely a result of changes of potentials over membranes of intracellular organelles rather than plasma membrane hyperpolarization. Hence, the previously described effects of fenpiclonil on amino acid and saccharide uptake cannot be explained by plasma membrane hyperpolarization.
Characterisation of benzimidazole‐resistant strains of Rhynchosporium secalis
Authors: Kendall Sheila , Hollomon Derek W. , Ishii Hideo , Heaney Steven P.
Published: November 2006

Abstract: Benzimidazole‐resistant mutants of Rhynchosporium secalis were easily generated in the laboratory using UV mutagenesis. Three levels of resistance were identified (low, LR; moderate, MR; high, HR), but there was no negative cross‐resistance with N‐phenylcarbamate fungicides. In all cases pathogenicity was reduced, in some cases drastically. Benzimidazole‐resistant field strains were first detected in 1990, some 15 years after this fungicide group was first used in UK barley crops. Unlike laboratory mutants, only HR phenotypes were isolated from the field, and all showed negative cross‐resistance to N‐phenylcarbamates. These field resistant strains were no less pathogenic than wild‐type ones. Carbendazim binding to tubulin‐like protein from HR phenotypes, whether generated in the laboratory or isolated from the field, was reduced.
Responses of phosphine‐resistant strains of two stored‐product insect pests to changing concentrations of phosphine
Authors: Rajendran Somiahnadar
Published: November 2006

Abstract: The susceptibility of eggs, pupae and adults of Tribolium castaneum (Herbst) and adults of Rhyzopertha dominica (F.), (both phosphine‐resistant strains) to phosphine at fixed concentration‐time (ct) products, with either constant or increasing or decreasing concentrations was studied at 25 (± 1)°C. At lower ct products, falling concentrations of phosphine generally caused reduced insect mortality in all the three exposure periods in the range 12 to 72 h. However, in R. dominica, both increasing and decreasing concentrations were less effective than constant concentrations. At higher ct products, no significant change in the mortality response was observed in either species after exposure to constant or changing concentrations. The findings indicate the need to maintain sufficiently high concentrations of phosphine until the end of the fumigation period.
Response of maize (Zea mays) inbreds and hybrids to rimsulfuron
Authors: Green Jerry M. , Ulrich Jim F.
Published: November 2006

Abstract: Extensive glasshouse studies characterized the varietal response to rimsulfuron of 37 inbreds of maize (Zea mays L.), representing the major inbred families used in hybrid seed production, and 20 defined hybrids from these inbreds. Tolerant hybrids were produced when one or both of its parents were tolerant. Sensitive hybrids occurred only when both parents were sensitive. Genetic analysis indicated that sensitivity is controlled by a single recessive gene. Dose‐response analysis showed varieties could vary more than 40000‐fold in sensitivity. Only the AHAS‐modified variety with the XA‐17 gene had changed enzyme sensitivity. This gene provided crop tolerance to very high rates of rimsulfuron and its interaction with an organophosphate insecticide. Breeders can eliminate varietal sensitivity in three ways: always use at least one tolerant hybrid parent, backcross sensitive inbreds with tolerant, or use an AHAS‐modified gene.
Study of dimethoate bioaccumulation in liver and muscle tissues of Clarias batrachus and its elimination following cessation of exposure
Authors: Begum Ghousia , Vijayaraghavan Shanta , Sarma P. Nageswara , Husain Sajid
Published: November 2006

Abstract: Dimethoate accumulation in liver and muscle tissues of a fresh‐water fish, Clarias bactrachus L., was measured by gas liquid chromatography. Fish were exposed to a sub‐lethal concentration of the pesticide in the laboratory water tank for a period of eight days. The accumulation increased up to two days, followed by decrease on the 4th and 8th days of exposure in both liver and muscle tissues. Maximum accumulation was found in liver. After eight days of exposure, fish were released into pesticide‐free water to study the rate of loss of the pesticide. It was found that liver and muscle tissues were cleared of dimethoate after four and eight days respectively.
Distribution of glyphosate and of its target enzyme inside wheat plants
Authors: Arnaud Laurence , Nurit Françoise , Ravanel Patrick , Tissut Michel
Published: November 2006

Enolpyruvylshikimate phosphate (EPSP) synthase activity has been measured in different organs of 1–14‐day‐old wheat seedlings growing in culture chambers. Enzyme activity was first detected after two days, and reached its maximum value at day 4. It remained almost unchanged for 14 days thereafter. During germination, one of the most important sources of enzyme was the seed scutellum. Later, the developed leaves contained 43% of the whole stock of enzyme. Although the enzyme distribution was not identical under light or in the dark, there was no evident light induction of EPSP synthase. High enzyme activity was found in the coleoptile, continuing for the whole life‐time of this organ, and which might be associated with its lignification. Five to 40% of the total enzyme was found in the roots, reaching a maximum at 14 days. At this stage, glyphosate applied to the first grown leaf was phloem‐transported to the sink organs, with no clear relationship being shown between EPSP synthase activity and herbicide quantity in each organ. At day 4, glyphosate treatment, by soaking the seedlings in the herbicide solution, was followed by an active phloem transport from the scutellum to the growing parts. The average internal concentration of radiolabelled compounds (glyphosate plus its possible derivatives) which induced wheat seedling growth decrease, was shown to reach 50 to 100 μM under our conditions.
Effect of chitin‐synthesis inhibitors on stored‐product beetles
Authors: Elek Jane A. , Longstaff Barry C.
Published: November 2006

The fecundity of four important coleopteran stored‐grain pests, Rhyzopertha dominica (Fab.), Sitophilus oryzae (L.), Oryzaephilus surinamensis (L.) and Tribolium castaneum (Herbst.) was assessed after exposure to wheat treated with five benzoylphenyl ureas (BPUs), members of the chitin‐synthesis inhibitor group of insect growth regulators (IGRs). Chlorfluazuron was found to control all four species more effectively than triflumuron, teflubenzuron, flufenoxuron or diflubenzuron. Two weeks of exposure of parents to 0.5 mg kg −1 of all the BPUs, except diflubenzuron, inhibited almost all F1 production and all the F2 production of each species. The fecundities of T. castaneum and O. surinamensis recovered almost to their untreated levels after two weeks of exposure to 1 mg kg −1 of BPUs followed by two weeks on untreated wheat, but the effect of the exposure persisted for at least two weeks on untreated wheat in adult S. oryzae and to a lesser extent in R. dominica. The mean F1 response of the four species after two weeks of exposure to four doses showed clearly that the four newer BPUs were all similar in their overall effectiveness and significantly more effective than diflubenzuron, although diflubenzuron was equally effective against S. oryzae. At 0.1 mg kg −1 triflumuron was less effective against O. surinamensis, while teflubenzuron and flufenoxuron were not very effective against the rice weevil, S. oryzae. Chlorfluazuron provided the most effective control of all four stored‐product pest species, including the weevil, S. oryzae. The BPUs show particular potential for use in the stored‐product industry because low dosages will effectively control the rice weevil in addition to the other major pest species.
Metabolism of the pesticide metabolites 4‐nitrophenol and 3,4‐dichloroaniline in carrot (Daucus carota) cell suspension cultures
Authors: Schmidt Burkhard , Thiede Brigitte , Rivero Christiane
Published: November 2006

The metabolism of [ 14 C]‐4‐nitrophenol and [ 14 C]‐3,4‐dichloroaniline (the xenobiotics are degradation products of parathion and propanil, respectively) was studied in cell suspension cultures of carrot (Daucus carota L.). 4‐Nitrophenol was transformed almost quantitatively to water‐soluble conjugates with minor amounts of non‐extractable residues. The conjugates identified were 1‐(O‐β‐D‐glucopyranosyl)‐4‐nitrobenzene and 1‐(6′‐O‐malonyl‐O‐β‐D‐glucopyranosyl)‐4‐nitrobenzene. In addition, two unidentified metabolites were observed, possibly a disaccharide and another malonylated glycoside of 4‐nitrophenol. Time‐course studies demonstrated that 4‐nitrophenol was rapidly taken up and conjugated; all metabolites remained associated with the cells rather than nutrient medium. 3,4‐Dichloroaniline was transformed quantitatively to water‐soluble conjugates and bound residues (3.6%). The water‐soluble metabolites were identified as 6′‐O‐malonyl‐N‐(β‐D‐glucopyranosyl)‐3,4‐dichloroaniline, N‐(β‐D‐glucopyranosyl)‐3,4‐dichloroaniline and N‐malonyl‐3,4‐dichloroaniline. A time‐course study showed that the glucosides were formed initially, then decreased, possibly due to hydrolysis. This decrease was paralleled by an increase of the main metabolite, N‐malonyl‐3,4‐dichloroaniline, which was predominantly recovered from the medium.
Activity of two novel insecticides against permethrin‐resistant Pseudoplusia includens
Authors: Thomas James D. , Mink Jeffrey S. , Boethel David J. , Wier Alan T. , Leonard B. Roger
Published: November 2006

Two experimental insecticides, AC 303,630 and MK 244, were tested against a laboratory colony and three field strains of Pseudoplusia includens (Walker). Topical application bioassays indicated that permethrin resistance in the field strains ranged from 3.9 to 489.0‐fold. In leaf dip bioassays, LC50 and LC90 values for AC 303,630 ranged from 6.7 to 15.1 mg litre −1 and 8.7 to 28.2 mg litre −1, respectively, for third‐instar larvae. The Louisiana 1991 field strain was significantly more susceptible to AC 303,630 than the laboratory and other field strains. The LC50 (but not LC90) for the Louisiana 1992 field strain was significantly higher than that of the laboratory strain. However, there was no difference in toxicity of AC 303,630 between the field strain with the highest level of permethrin resistance and the laboratory strain. LC50 and LC90 values for MK 244 in leaf dip bioassays ranged from 0.014 to 0.023 mg litre −1 and 0.079 to 0.174 mg litre −1, respectively. There were no significant differences in LC 50 or LC 90 among any of the strains for MK 244. Field trials in soybean were also conducted in 1991 and 1992 in an area of Louisiana where permethrin efficacy against P. includens has declined. In both years, AC 303,630 at 0.11–0.22 kg ha −1, and MK 244 at 0.0042–0.0084 kg ha −1, provided significantly better control than permethrin at 0.11 kg ha −1, and control equal to the recommended standard, thiodicarb. These studies indicate no cross‐resistance exists between the experimental insecticides and permethrin.
Photochemistry of parathion in the plant cuticle environment: Model reactions in the presence of 2‐propanol and methyl 12‐hydroxystearate
Authors: Schwack Wolfgang , Andlauer Wilfried , Armbruster Wolfgang
Published: November 2006

On UV‐irradiation (λ > 280 nm), photodegradation of parathion dissolved in 2‐propanol took place mainly by reduction of the phenylnitro group. The photoreduction intermediates so formed then combined, yielding primarily azoxyparathion which, upon further irradiation, rearranged into 2‐hydroxyazoparathion.

When parathion was irradiated in the presence of the cutin acid 12‐hydroxystearic acid (as the methyl ester), azoparathion, azoxyparathion and 2‐hydroxyazoparathion were the dominant photoproducts if the reaction was performed in thin‐layer films of the 12‐hydroxystearate. Irradiation of parathion dissolved in a solution of the 12‐hydroxystearate in cyclohexane yielded mainly paraoxon.

Furthermore, in all experiments, photolysis of the P—O ester bonds of the parent compound as well as of the photoproducts was observed at low levels.
Molecular connectivity and hydrophobicity in the study of antifeedant activity of clerodane diterpenoids
Authors: Luco Juan M. , Sosa Mart A. E. , Cesco Juan C. , Tonn Carlos E. , Giordano Oscar S.
Published: November 2006

Feeding deterrent activities of twelve clerodane diterpenoids towards Tenebrio molitor (Coleoptera: Tenebrionidae) larvae have been correlated using molecular connectivity indexes (3χc, 4χc, °ΔX) and hydrophobicity constants (log K′w) obtained by reverse‐phase liquid chromatography (RPLC). The equations obtained suggest that both the degree of branching and the electronic characteristics of the compounds under study have a dominant role in the observed antifeedant activity. The information obtained from the correlations should be useful in designing more potent analogues.
Behavioral responses of red‐winged blackbirds (Agelaius phoeniceus) to viewing a conspecific distressed by 4‐Aminopyridine
Authors: Conover Michael R.
Published: November 2006

4‐Aminopyridine (4‐AP) is the only pesticide that can be legally used in the US to reduce bird damage in ripening grain fields. Birds that consume grain baits treated with 4‐AP (‘Avitrol’ FC‐99®) exhibit erratic behavior and emit vocalizations that presumably scare away the rest of the flock. Yet the behavior of 4‐A Pintoxicated birds has not been documented, and we do not know how other birds react when observing these intoxicated birds or what these observers learn from their experience. Hence, we examined the behavior of 15 4‐A Pintoxicated red‐winged blackbirds (Agelaius phoeniceus (L.)) and found that initial signs of intoxication occurred 12.5 min after consumption of the bait, with death following 16.3 min later. During this 16‐min intoxication period, birds gradually lost muscular control, making their movements and vocalizations weaker until hardly perceptible. Other captive red‐winged blackbirds (‘observers’) gave more alarm calls while witnessing a 4‐A P‐intoxicated bird in one room of their cage (treatment period) than they did during the pre‐treatment period. Immediately after the intoxicated bird died and was removed from the room, the observers' behaviour returned to pre‐treatment levels. Broadcasting calls of an intoxicated bird or the placement of an untreated bird in one of the rooms had little effect on the observers' behavior. In another experiment, the placement of a 4‐A Pintoxicated or untreated red‐winged blackbird or the broadcast of calls of an intoxicated bird at a feed station did not affect the number of free‐ranging conspecifics feeding, within sight of, or vocalizing at, these feeder stations. These results suggest that red‐winged blackbirds learn little from witnessing a distressed conspecific.
Solid‐phase extraction of pesticides from surface water using discs, bulk sorbents and supercritical fluid extraction (SFE)
Authors: Bengtsson Staffan , Berglöf Tomas , Granat Sophia , Jonsäll Göran
Published: November 2006

Extraction of pesticides from river water samples using the classical liquid‐liquid extraction (LLE) approach is a labour‐intensive procedure that requires relatively large volumes of solvent. With the solid‐phase extraction (SPE) technique using membranes, the volumes of solvent are reduced. However, it is necessary to pre‐filter and often also to acidify the river water to pH < 2 to prevent plugging of the capillary pores. This low pH may decompose some pesticides and therefore a fast and inexpensive technique with bulk sorbent and without prefiltration and acidification was developed.

To reduce the solvent volumes further, extractions of discs and bulk sorbent were performed with supercritical fluids (SF). Seven pesticides with different polarities were studied. Mean recoveries from the bulk sorbent and the discs were of the same order (61%). However, recoveries from the latter improved to 82% with SFE of the discs, providing results comparable to LLE (94%) recovery.
Fungicidal activity of the synthetic putrescine analogue, (E)‐l,4‐diaminobut‐2‐ene, and derivatives
Authors: Havis Neil D. , Walters Dale R. , Foster Sally A. , Martin William P. , Cook Fiona M. , Robins David J.
Published: November 2006

The putrescine analogue. (E)‐1,4‐diaminobut‐2‐ene (E‐BED), synthesized as the dihydrochloride salt, controlled five economically important crop pathogens, Erysiphe qraminis DC f.sp. hordei Marchal. Uromyces viciae‐fabae (Pers.) Schroet, Botrytis fabae Sardina, Podosphaera leucotricha (Ell. & Ev.) Salm. and Phytophthora infestans (Mont) De Bary. The Z‐isomer. Z‐BED. was also fungicidal, although less so than E‐BED. Post‐inoculation treatment with E‐BED gave greater control of powdery mildew infection on barley and rust and chocolate spot on broad bean than did pre‐inoculation application. It was also effective in vitro against Botrytis cinerea Pers. ex Fr., Pyricularia oxyzae Br. & Cav. and Pyrenophora avenae Ito & Karibay. When P. avenae was grown in the presence of E‐BED dihydrochloride at 81·5 mg litre−1, growth was reduced by 58% and there were significant reductions in soluble ornithine decarboxylase (ODC) and S‐adenosylmethionine decarboxylase (AdoMetDC) activity. These changes were accompanied by a sevenfold increase in putrescine concentration, a 60% increase in spermine concentration and a 32% reduction in spermidine concentration within the fungal tissue.
Selectivity of SMY 1500 (4‐amino‐6‐tert‐butyl‐3‐ethylthio‐l,2,4,triazin‐5(4H)‐one) in Triticum durum
Authors: García‐Valcárcel Ana , Villarroya Mercedes , Chueca Ma Cristina , Tadeo José Luis , García‐Baudin José María
Published: November 2006

Susceptibility to SMY 1500 (4‐amino‐6‐tert‐butyl‐3‐ethylthio‐1.2.4‐triazin‐5(4H)‐one) was studied in durum wheat (Triticum durum Desf.) cultivars in growth‐chamber assays. Weight reduction, photosynthesis inhibition and herbicide levels were determined at various times after a 24‐h herbicide treatment in two cultivars of durum wheat, one cultivar of spring wheat (Triticum aestivum L). and in the weed Bromus diandrus (Roth). Measurements of weight reduction distinguished between plants tolerant and plants susceptible to SMY 1500. Tolerant cultivars showed a lower herbicide content and photosynthesis inhibition than susceptible plants after the 24‐h treatment. Thereafter, herbicide levels and photosystem II inhibition decreased faster in tolerant plants. Comparison with previous work showed that plants tolerated doses of SMY 1500 about four times higher than of its analogue, metribuzin. Herbicide content in leaves just after treatment, and rate of detoxification may explain the selectivity of SMY 1500 in these cereals.
Root absorption and translocation of 5‐substituted analogs of the imidazolinone herbicide, imazapyr
Authors: Little Desiree L. , Shaner Dale L. , Ladner David W. , Tecle Berhane , Ilnicki Richard D.
Published: November 2006

In preparation for assessing quantitative structure‐activity relationships (QSAR) for root absorption and translocation of imidazolinones herbicides, 13 radiolabeled analogs of imazapyr (2‐(4‐isopropyl–4‐methy1–5‐oxo‐2‐imidazolin‐2‐yl) nicotinic acid) substituted in the 5‐position of the pyridine ring were evaluated in corn (Zea mays L.) and sunflower (Helianthus annuus L.). The compounds (10 μm) were supplied to the roots through a hydroponic solution for 8 h and, following harvest, plant tissues were either combusted to measure total uptake of radiolabeled material or were extracted for determination of the extent of degradation of the parent compound. Root absorption in both species varied by two orders of magnitude among analogs while translocation, expressed as a percentage of absorption, varied by only three‐ or four‐fold. Few differences were observed for translocation of radioactivity from sunflower stems to leaves. Although six of the analogs were partially metabolized in corn, little metabolism of the imidazolinone analogs occurred in sunflower. These data indicate that meaningful models of root absorption and subsequent translocation to shoots may be developed for 5‐substituted analogs of imazapyr, particularly when applied to sunflower.
Key chemical inputs to new herbicides: Intermediates, processes and mechanistic investigations
Authors: Dingwall John G.
Published: November 2006

The key chemical inputs that led to the discovery of the three herbicides CGA 215684 (a cyclohexanedione), CGA 244126 (a substituted pyridine) and CGA 152005 (sulfonylurea) and the plant‐growth regulant CGA 163935 (a cyclohexanedione) are described.
Nuclear DNA analysis of maize seedlings treated with the triazole fungicide, triticonazole
Authors: Biradar Digambareppa P. , Pedersen Wayne L. , Rayburn A. Lane
Published: November 2006

Maize kernels were treated with the fungicide triticonazole (RP‐727), belonging to the triazole family. The nuclear DNA content was analyzed in various maize plant organs by using flow cytometry. Two fluorochromes with different DNA binding mechanisms were used for probing nuclear DNA and chromatin structure. Results indicated nuclear alterations with the use of triticonazole and the alterations observed were different in the various tissues analyzed. Active meristematic plant organs, such as root tip, did not show any significant change in nuclear DNA, but chromatin structure was altered with increasing concentrations of fungicide. Stem and mesocotyl showed both DNA and chromatin condensation changes with triticonazole concentration, but the trends observed in these two plant organs were opposite. The magnitude of the alterations was minute in the different plant organs studied. These alterations do not appear to be deleterious for normal plant development.
Growth‐linked and cometabolic biodegradation: Possible reason for occurrence or absence of accelerated pesticide biodegradation
Authors: Robertson Boakai K. , Alexander Martin
Published: November 2006

A study was conducted to relate the occurrence of accelerated pesticide biodegradation to the susceptibility of the pesticides to growth‐linked degradation or cometabolism. The mineralization of 2,4‐D was initially slow but then became rapid, and a second application was mineralized with no acclimation phase and more rapidly than the first. The numbers of 2,4‐D‐degrading micro‐organisms increased markedly following its first application and then declined, but the population size increased after a second addition. Glyphosate was rapidly and extensively mineralized following the first and second applications to soil, and the abundance of organisms able to degrade it rose after the first addition and remained high before and following the second application. Propham (IPC) mineralization was detected only 15 days after its application but the degradation was rapid thereafter, and the second addition was rapidly and extensively mineralized with no acclimation phase. The population of propham‐degrading micro‐organisms was initially small, but increased markedy 10 days after the initial herbicide addition and was still large at the time of the second application. The rate of carbofuran biodegradation in the test soil was the same following the first and second applications, and the abundance of carbofuran‐metabolizing microorganisms did not change appreciably as a result of soil treatment with the insecticide. Simazine mineralization was slow, although the rate was higher following the second addition; however, the number of simazine‐degrading organisms did not increase appreciably. From 10 to 12% of the14C from radiolabeled 2,4‐D, propham, glyphosate or glucose was usually incorporated into the microbial biomass of soil but 0.82% or less of the14C from simazine or ring‐ or carbonyl‐labeled carbofuran was converted to biomass. It is suggested that pesticides that support microbial growth may be subject to accelerated biodegradation if the population remains large until the pesticide is applied again. Pesticides that do not support growth may not be subject to accelerated biodegradation.
Selection of compounds acting as aphid development and reproduction regulators: Laboratory screening
Authors: Kuldova Jelena , Hrdy Ivan , Wimmer Zdeně
Published: November 2006

Newly synthesized compounds were examined in screening tests with the pea aphid, Acyrthosiphon pisum (Harris) for juvenilizing effects. usign the spray‐residue method. Two derivatives of 2‐(4‐hydroxvbenzyl)eyclohexanone bearing a carbamate or an ether group were found to be the most active inhibitors of development and reproduction. Tests with the hop aphid, Phorodon humuli (Schrank) of insecticide‐susceptible and multi‐resistant biotypes and with the green peach aphid, Myzus persicae (Sulzer) confirmed their biological activity. Cross‐resistance between conventional insecticides and juvenoids was not indicated. The formation of supernumerary larvae, where retention of larval cauda and corresponding larval characters were observed and reproduction was entirely suppressed, was recognized as the critical result of the juvenilizing effect. The production of viable progeny was not affected in those aphids which survived treatment and developed normal adult external genitalia.
The trapping of spray droplets by insects
Authors: Bache David H.
Published: November 2006

The paper describes a methodology for specifying the deposition of spray droplets on flying insects and insects at rest on a quantitative basis. Processes of deposition by sedimentation and inertial impaction are viewed in terms of a deposition velocity defined by vg = vsax + Eiuaz, in which vs is the droplet settling velocity, u the air speed relative to the insect, Ei a collection efficiency associated with inertial impaction and ax, az signify horizontal and vertical projections of a representative trapping area. Published data on the deposition of small droplets (diameter < 20μm) on mosquitoes show that the trapping efficiency is dominated by inertial impaction and it is assumed that the collection efficiency is specified by Ei = St2/(St + 0.2)2 in which St is the Stokes number. Analysis of a second data set regarding the deposition of larger drops on flying locusts shows that the dependence of the observed collection efficiency on droplet size can be explained satisfactorily by this simplified approach. Further, it is demonstrated that a characteristic length which forms an essential component of the Stokes number is matched to the general size of the insect. The paper concludes with an analysis of a further data set concerning the deposition of small drops onto resting tsetse flies; this provides insight into the effective air speed controlling the deposition process.
Supercritical fluid chromatography—finding a place in the chromatographers' arsenal?
Authors: Bond Paul M.
Published: November 2006

In the mid‐ to late 1980s, supercritical fluid chromatography (SFC) was ‘reborn’ as a technique for the 1990s. Supercritical fluids have physical properties (viscosity, diffusivity and density) intermediate between those of licuids and gases. Analyte solubilities are similar to those in some liquid chromatography solvents and the gas‐like properties of supercritical fluids make higher resolution or shorter analysis times possible.

Applications and experience with a home‐built SFC system, as well as methods developed elsewhere, are described. The successes and limitations of the technique are reviewed together with details of the instrumentation.

Areas in which SFC may become the procedure of choice include multi‐residue methods, non‐polar analyses, micro‐preparative uses and for difficult extractions. The advances in GC and HPLC technology, however, lead us to believe that SFC will remain a specialist technique, appealing only to a minority of analysts.
Influence of application methods on the degradation of permethrin in laboratory, soil aerobic metabolism studies
Authors: Skidmore Michael W. , Kirkpatrick David , Shaw David
Published: November 2006

The effects of application rate, volume, solvent and soil moisture content on the kinetics of mineralization and degradation, of [14C] permethrin have been studied in a sandy loam soil under standard laboratory conditions. During the incubation period, up to 32 days, the temperature and moisture level of the soil were controlled. Apart from the effects of application rate, which have been widely reported, application volume had the most significant effect on mineralization rate and T1/2. [14C]Permethrin, at a level of a 1 mg kg−1 in the soil, applied in 100 μl of methanol, resulted in the evolution of 14% of the applied radiochemical as [14C] carbon dioxide over 30 days. The same level applied in 1000 μl mineralized at a faster rate, with 30% [14C]carbon dioxide evolved over 30 days.

The test chemical applied to soil in methanol mineralized at a significantly faster rate than a similar concentration applied in ethanol. There was no significant difference when comparing applications made using acetonitrile with those using methanol or ethanol. The addition of formulation ingredients resulted in little or no variation in mineralisation rate compared to an equivalent application volume of methanol/water.
Bemisia tabaci in the Netherlands; here to stay?
Authors: Fransen Joanne J.
Published: November 2006

In autumn 1987, the first observations were made in the Netherlands of a whitefly species identified as type ‘B’ of the sweet potato whitefly, Bemisia tabaci (Gennadius), on the host plant poinsettia, Euphorbia pulcherrima Willd. ex Klotzsch. Although an eradication programme was initiated, total eradication was not obtained. Over the years B. tabaci has persisted on poinsettia and slowly spread to other crops like Begonia, Bouvardia, Gerbera and Hibiscus. Vegetables like tomato, cucumber and egg plant have also become infested.

B. tabaci often develops extensively during the summer season due to its better adaptation to temperatures of ⩾25°C compared with the greenhouse whitefly, which develops more readily at 20°C. During the poinsettia growing season, high population numbers of B. tabaci will not develop, but any plants showing visible signs of infestation, such as an empty pupal case, are rejected at the auction. The integration of biological and chemical control is expected to show better potential than the use of insecticides, as insecticide resistance has already been observed. Several natural enemies, such as certain strains of the parasitoids Encarsia formosa Gahan and Eretmocerus californicus Howard, as well as the predators Delphastus pusillus Leconte and Macrolophus caliginosus Wagner, are being tested in green‐houses. Research is also carried out regarding the use of insectpathogenic fungi such as Aschersonia spp., Verticillium lecanii (Zimm.) Viegas and Paecilomyces spp.
A bioassay for determining simazine in water using aquatic flowering plants (Ceratophyllum oryzetorum, Ranunculus trichophyllus and Alisma plantago‐aquatica)
Authors: Ou Ziqing , Sun Tieheng , Zhang Hairong
Published: November 2006

A simple and rapid bioassay for the measurement of simazine in water using aquatic flowering plants (Ceratophyllum oryzetorum Kom., Ranunculus trichophyllus Chaix. and Alisma plantago‐aquatica L.) is reported in this paper. It is based on the effect of simazine on the amount of oxygen produced by photosynthesis which is measured directly using a Clark‐type oxygen electrode. This method is rapid, sensitive, and capable of measuring a simazine concentration of 0.02 mg litre−1 within 10 min of treatment. The precision of this method was examined with spiked river water by comparing the results obtained with HPLC. Mean recoveries of simazine measured by bioassay using C. oryzetorum were 96 to 100% which were comparable to those (98 to 100%) obtained with C18 column extraction and HPLC measurement. The results obtained by the two methods showed excellent agreement. Maintenance of stock cultures of the plants and the bioassay procedure itself were much simpler and more easily conducted than methods using algae.
Modelling penetration of plant cuticles by crop protection agents and effects of adjuvants on their rates of penetration
Authors: Schönherr Jörg , Baur Peter
Published: November 2006

A theory of cuticular penetration of crop protection agents (CPAs) is presented, which incorporates properties of cuticles and cuticular waxes as well as properties of active ingredients and adjuvants. Based on this theory, two models are developed which are analytical in the sense that they help to quantify and understand (i) differences in permeability among cuticles from different species, (ii) effects of properties of CPAs on permeabilities of cuticles and rates of uptake and (iii) the effects of adjuvants on properties of cuticles and rates of uptake of CPAs. The models can be used to predict rates of uptake of CPAs as affected by properties of cuticular waxes, active ingredients and adjuvants. However, before this can be done, a constant, two parameters and at least two variables must be estimated. Properties of cuticles are accounted for by the constant D0/Δx and the parameter β′. The former, the ratio of the mobility of a hypothetical molecule having zero molar volume (D0x) divided by the path length (Δx) across the cuticle, has the dimension of velocity (ms−1) and is independent of the solubility of the CPA. The latter is a measure of size selectivity of the cuticle. Differences in permeabilities of cuticles from different species increase with increasing size of active ingredients due to size selectivity (β′). Removing cuticular waxes from Citrus cuticles increased D0/Δx by a factor of 2042, while β was not affected. Differential solubility of CPAs is considered part of the driving force and at least two different partition coefficients are needed to account for differences in solubilities in cuticular waxes, cutin, water and the formulation residue on the surface of the cuticles. Adjuvants are solvents in the formulation residue on the leaf surface once the carriers (water and other volatile solvents) have evaporated and certain adjuvants also act as accelerators; they penetrate the cuticle and increase D0/Δx. Thus, accelerators increase rates of uptake and this effect depends on two factors, (i) the intrinsic activity of the accelerator and (ii) rate of penetration into the cuticle, because the active ingredients follow the accelerator front across the cuticle. Since accelerators penetrate from the formulation residue into the cuticle, the volume of the formulation residue decreases with time. This maintains high concentrations of CPAs in the formulation residue and, thus, maximum driving forces and rates of penetration. To utilise fully this dual accelerator effect, it is necessary to match velocities of penetration of accelerators and active ingredients accurately.