bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel approaches to integrated pest and disease control in glasshouse vegetables in the Netherlands
Authors: Van Steekelenburg Nico A. M.
Published: November 2006

As a result of government policy and consumers' attitudes to environmentally compatible growing systems, research is focused on reduction of pesticide input into the environment. This aim is approached in different ways.

With so‐called “closed growing systems”, soil fumigants are no longer needed, resulting in an estimated 60% reduction in the total use of pesticides. Further, far smaller quantities of (systemic) pesticides need to be added to plants, via the nutrient solution, than with soil‐grown crops. Water disinfestation is essential to minimize the spread of diseases and heat treatment and ozonization are already used under commercial conditions. Filtration appears to be neither reliable nor practical. Other disinfestation methods are under investigation.

Ventilators may be provided with insect‐proof screens to minimize infection pressure, especially on young plant material. Air filters in combination with mechanical ventilation may be an option for the future to raise healthy plants.

A further reduction in the use of pesticides can be achieved by developing biological and integrated control of insects and fungi. Simultaneous application of several biocontrol methods in the fruit vegetable area has increased the complexity of IPM. Open rearing systems of parasitoids on alternative hosts to control cotton aphids and leaf miners are promising. IPM is highly dependent on the availability of selective chemicals.

Biological control of root‐infecting fungi in substrate crops shows promise. Integrated control of powdery mildew in cucumbers using a combination of nutritional and climatic management and varieties showing partial resistance will be studied.

Improvement of application techniques for pesticides is being studied by plant pathologists in cooperation with technical experts. The aim is to reduce pesticide application rates, to minimize losses to the environment and to avoid health risks for the worker.

By developing decision‐support systems for crop protection, optimal use of beneficial insects is achieved and unnecessary applications of chemicals are avoided. A programme to develop such a system for the sweet pepper crop is under way.
Practical crop protection in a glasshouse environment
Authors: Veanman A. Frits
Published: November 2006

Integrated pest management in glasshouse crops in the Netherlands is discussed with particular reference to existing and potential biological control agents and methods.
IPM in protected crops: Concerns, challenges and opportunities
Authors: Van Oosten Henk J.
Published: November 2006

The Dutch government has a coherent, long‐term policy regarding attainment of a sustainable development affecting agriculture and horticulture, the requirements of which are very strict and will be difficult to satisfy. The growers of protected crops try to meet these requirements by developing so‐called closed growing systems. Two other approaches in the policy are a substantial reduction of the volume of pesticides used and a very critical evaluation of the pesticides permitted. In this governmental policy, Integrated Pest Management has shown prospects in horticulture; it will play a very important role in the near future but is now considered as part of the broader concept of Integrated Production Systems.

The glasshouse industry is very actively developing its own strategy to satisfy government targets and market demands for high‐quality products produced by environmentally safe methods. The vegetable auctions have developed a policy of environmentally conscious production which should put the vegetable industry into a strong marketing position for its produce.
Control of seedborne pathogens and diseases of soybean seeds and seedlings
Authors: Sinclair James B.
Published: November 2006

The control of pathogens, including two bacteria, nine fungi and a virus that cause diseases of soybean seeds and seedlings is discussed. Control methods include general management practices, biocontrol agents, fungicides applied to seeds and foliage, and thermotherapy. Guidelines for the use of seed treatment and foliar fungicides are given. The fungicides commonly used are listed and the interaction between certain fungicides and Bradyrhizobium inoculant is discussed.
The fate and insecticidal activity of pirimiphos‐methyl in stored wheat grain
Authors: Matthews Wendy A. , Maliphant Paula
Published: November 2006

The degradation of [14C]pirimiphos‐methyl was investigated on a 1‐kg bulk of grain stored in the laboratory at 15°C for 28 weeks. Breakdown of pirimiphos‐methyl was slow, leaving 77% of the applied dose unchanged at the end of the experiment. The major degradation product was the hydroxypyrimidine (up to 12.5% of the applied dose) with the remainder of the residue (up to 12.1%) remaining within the grain tissues after solvent extraction. The efficacy of the treatment was assessed in a parallel experiment by bioassay of a 5‐kg bulk of grain dosed with unlabelled pirimiphos‐methyl. 100% Mortality of an organophosphateresistant strain of Oryzaephilus surinamensis L. was maintained throughout the experiment whereas some survival of an organophosphate‐resistant strain of Tribolium castanewm (Herbst) occurred after 12 weeks of storage. This increased to give a 20% survival rate at the end of the experiment.
Interaction between optical isomerism and plant pharmacological action, change of modes of action and chirality of 1‐(α‐methylbenzyl)‐3‐p‐tolylurea
Authors: Omokawa Hiroyoshi , Kawata Yoshinori , Konnai Makoto
Published: November 2006

The optical isomers, (R)‐1(α‐methylbenzyl)‐3‐p‐tolylurea ((R)‐MBU) and (S)‐1‐(α‐methylbenzyl)‐3‐p‐tolylurea ((S)MBU), which are analogues of daimuron [1‐(α,α‐dimethylbenzyl)‐3‐p‐tolylurea], a herbicide for Cyperaceae weeds and a safener for paddy rice, exhibited different biological responses. These two physiological properties of daimuron were observed separately in (R)‐MBU and (S)‐MBU. Only (R)‐MBU had herbicidal activity against Cyperaceae weeds, while the (S)‐isomer was a more effective safener against bensulfuron‐methyl (BSM) injury of rice seedlings than was (R)‐MBU. (S)‐MBU promoted root growth of rice seedlings, but the (R)‐enantiomer inhibited root growth. (S)‐MBU was a more potent inhibitor than (R)‐MBU on PS II reaction of spinach broken chloroplasts. Furthermore, (S)‐MBU and (R)‐MBU showed cross intergenus selective phytotoxicity among the Gramineae plants, Oryza sativa L. (rice, cv. Tsukinohikari, japonica), Triticum aestivum L. (wheat, cv. Norin No. 61) and Echinochloa crusgalli var. frumentacea Wight, on root growth inhibition in the dark.
In‐vivo evaluation of adjuvants for more effective control of celery leaf‐spot (Septoria apiicola) and powdery mildew (Erysiphe graminis) of wheat with fungicides
Authors: Amer Mostafa A. , Hoorne Dirk , Poppe Josef
Published: November 2006

The effects of seven adjuvants (at 0, 0.5, 1.0 and 2.0 g litre−1) on the efficacies of four fungicides al 0.5 g litre−1 were studied in the laboratory for the control of leaf‐spot in celery (caused by Septoria apiicola) and powdery mildew on winter wheat (caused by Erysiphe graminis). The most effective fungicides for controlling leaf‐spot were: tebuconazole + triadimenol = flutriafol > mancozeb + oxadixyl > prochloraz. However, addition of adjuvant to the fungicides gave a modified pattern of effectiveness. The efficacy of flutriafol was strongly enhanced by addition of all adjuvants, but those of prochloraz and mancozeb+oxadixyl only partially so. The tested adjuvants were mineral oil + surfactant, a polymer/alkoxylated alkyl ether blend, an ethoxylated alkylphenol, an ethoxylated hexitan ester blend, an ethoxylated nonylphenol and an alkylpolysaccharide‐ based adjuvant mixture. However, the addition of adjuvants to tebuconazole + triadimenol had a negative effect. Of all the adjuvants tested, the nonylphenol ethoxylate and a mixture of mineral oil /surfactant and alkylpolysaccharides gave the highest efficacy with the fungicides, while the mineral oil/surfactant and the alkylpolysaccharides alone were less effective. There was a positive relationship between high concentrations of adjuvants and their effectiveness, but there were some exceptions.

The most effective fungicides for control of powdery mildew in wheat were prochloraz, mancozeb + oxadixyl and tebuconazole + triadimenol. There was a linear relationship between the high efficacy of the fungicide and the concentration of adjuvants to control powdery mildew in wheat. The highest concentration of adjuvant (2‐0 g litre−1) gave the highest efficacy for the fungicides.
Characterizing pesticide and surfactant penetration with isolated plant cuticles
Authors: Bukovac Martin J. , Petracek Peter D.
Published: November 2006

A survey is presented of the use of isolated leaf and fruit cuticles in studying foliar penetration. Isolated cuticles, which represent the prime barrier to penetration, provide a physical system with which transport studies can be conducted under well‐defined and highly controlled conditions while avoiding the physiological effects of biologically active compounds on the system. Most studies with isolated cuticles have focused on sorption, desorption and infinite‐dose cuticular transport of compounds in aqueous systems. Partition coefficients can be calculated for pesticides from sorption data, thereby yielding information on the solubility of the compounds in the cuticle. Permeance and diffusion coefficients can be calculated from cuticular transport studies. These transport parameters provide for a better understanding of the mechanisms of cuticular penetration. Further, they are useful in comparing both the penetration characteristics of selected compounds and permeability of cuticles. Transport systems, using isolated cuticles, may be used to quantify the effects of spray additives on pesticide penetration. A finite‐dose system is described that may be useful in studying spray droplet/deposit interactions with the cuticle and, concurrently, following transcuticular penetration from droplets/deposits on the surface. These systems may prove useful in optimizing spray formulations and spray parameters, leading to more efficient pesticide development and application.
Fungicidal activity of the polyamine analogue, keto‐putrescine
Authors: Foster Sally A. , Walters Dale R.
Published: November 2006

The polyamine analogue, keto‐putrescine, was shown to provide substantial control of infections by six economically important plant pathogens, with EC50 values ranging between 57 and 82 mg litre−1. However, keto‐putrescine was relatively less effective in vitro against Phytophthora infestans, Pyricularia oryzae and Pyrenophora avenae, with EC50 values ranging from 145 to 340 mg litre−1. In contrast, the polyamine analogue N‐acetylputrescine had to effect on in‐vitro growth of P. avenae or P. oryzae or infection of barley seedlings with powdery mildew. When P. avenae was grown in the presence of keto‐putrescine, there were small, insignificant reductions in ornithine decarboxylase activity, with more substantial, significant reductions in S‐adenosylmethionine decarboxylase activity. These changes were accompanied by a 43% reduction in spermidine concentration and increased concentrations of spermine and cadaverine.
The dietary toxicity of flocoumafen to hens: Elimination and accumulation following repeated oral administration
Authors: Eadsforth Charles V. , Gray Alan , Huckle Keith R. , Inglesfield Christopher
Published: November 2006

In a dietary toxicity study, laying hens received a diet containing the rodenticide flocoumafen at concentrations of 1.5, 5, 10 and 50 mg kg−1 for five consecutive days. The LC50 at termination following a 28‐day observation period was 16.4 mg kg−1.

Livers of birds which received doses of flocoumafen between 5 and 50 mg kg−1 had concentrations of flocoumafen (1.5 nmol g−1) that were independent of dose. The data indicate the presence in hen liver of a saturable high‐affinity flocoumafen binding site with similar characteristics and capacity to that of the quail and rat. Residues of flocoumafen in samples of breast and leg muscle were low in all exposure groups. Higher, dose‐related residues were found in samples of abdominal fat and skin‐associated fat and there was a clear demonstration of the transfer of dose‐related residues into eggs.

In a separate study in which hens were dosed with [14C]flocoumafen for five consecutive days at a daily rate of 1 and 4 mg kg−1 body weight, the majority (68 %) of the daily radioactive dose was eliminated over the following 24 hours via excreta. Residues in liver at death or when killed accounted for < 1 % of the cumulative administered radioactivity. Residues in eggs were located primarily in the yolk with maximum concentrations 1.0 mg kg−1 or 0.18% of the low dose; 2.1 mg kg−1 or 0.06% of the high dose as [14C]flocoumafen equivalents were observed at 10 days after start of dosing. Some 40 % of the total activity in the yolk was unchanged flocoumafen.
Foliar uptake of organosilicone surfactant oligomers into bean leaf in the presence and absence of glyphosate
Authors: Zabkiewicz Jerzy A. , Stevens Peter J. G. , Forster W. Alison , Steele Kevin D.
Published: November 2006

The nonionic organosilicone surfactant ‚Silwet’︁® L‐77TM (1, 2 and 5 g litre−1) and [14C]glyphosate‐monoisopropylammonium (10 g litre−1 a.e.), were applied, alone and in combination with each other, to the upper surfaces of leaves of Vicia faba L. plants growing in a controlled environment. Over 80% of the glyphosate was taken up within 10 min in the presence of 5 g litre−1 L‐77, with no further uptake over the remaining period. A similar pattern of uptake was observed with 2 g litre−1 L‐77, but only 30% was taken up initially. In the presence of 1 g litre−1 L‐77 initial glyphosate uptake was only 15%, but uptake continued, subsequently reaching c.25% after 360 min, this behaviour being essentially the same as that of glyphosate when applied without surfactant. The uptake of L‐77 was not significantly affected by the addition of glyphosate, being c.80% within 10 min at 5 g litre−1, but with a slow, further increase of c.12%. At 2 g litre−1 uptake was c.45% within 10 min, rising to c.70% by 360 min. The 1 g litre−1 solutions showed a similar pattern, with uptake increasing from c.35% at 10 min to over 60% after 360 min. In the absence of glyphosate, individual L‐77 oligomers penetrated at similar rates. In the presence of glyphosate, however, some discrimination was evident among the oligomers, in particular when the surfactant was added at 1 g litre−1. Literature on the foliar uptake of surfactants is reviewed and discussed in relation to the results of this study.
Diffusion of three ethoxylated octylphenols across isolated plant cuticles
Authors: Coret Joël , Gambonnet Bernadette , Brabet Frederic , Chamel André R.
Published: November 2006

The diffusion of three polydisperse [3H]ethoxylated octylphenols (5, 10 and 16 EO) through isolated plant cuticles was studied using diffusion half‐cells and droplet application. The diffusion half‐cells were used to determine the influence of ethylene oxide (EO) content and of surfactant concentration on the diffusion of the surfactants across the cuticle at a relatively constant concentration gradient. The influence of EO content, of temperature and of surrounding relative humidity on diffusion of the surfactants across the cuticle was determined with droplet application.

Measurements in diffusion half‐cells showed that flux was lowest for OP16 in comparison to OP5 and OP10. Diffusion coefficients were 0.92, 3.17 and 2.18 × 12−12 cm2 s−1 for OP5, OP10 and OP16 respectively in pepper fruit cuticles. Flux of OP10 across pepper fruit cuticles increased with surfactant concentration in the donor cell (from 5 to 40 g litre−1), the diffusion coefficient of OP10 in the cuticle rising from 3.79 to 21.3 × 10−12 cm2 s−1.

Surfactant penetration through pepper fruit and rubber‐plant leaf cuticles was initially very rapid after droplet application, decreasing gradually after 24 h. Flux of OP16 across cuticles of both species was lower than for the other two octylphenols. Penetration of OP10 and OP16 through pepper fruit cuticles was greater at low (40%) than at high (95%) relative humidity. Transfer of OP10 increased considerably as temperature increased from 5°C to 30°C. The value obtained for the diffusion activation energy was −70.3 kJ mol−1.

The experimental results are discussed in the light of the free‐volume theory with respect to diffusion of organic molecules in polymers.
The role of surface tension of spreading droplets in absorption of a herbicide formulation via leaf stomata
Authors: Buick Rosalind D. , Buchan Graeme D. , Field Roger J.
Published: November 2006

The foliar absorption by field bean (Vicia fabu L.) of triclopyr‐triethylamine from solutions containing an organosilicone surfactant, ‚Silwet L‐77’︁ at 0, 1.0, 2.5 and 5.0 ml litre−1, was investigated using fluorescence and radiotracer studies. Physical characteristics such as formulation surface tension and contact angles of droplet formed on the field bean leaf were determined and combined to obtain a critical surface tension value (γcritical) of 19.5–22.9 mN m−1 for the adaxial leaf surface. The apparent surface tensions of the three formulations containing L‐77 were equivalent and low, an average of 22 mN m−1, which would be sufficiently low to permit stomatal infiltration. The presence of L‐77 at 2.5 or 5.0 ml litre−1 significantly enhanced the uptake of triclopyr‐triethylamine into the leaf, particularly via stomatal pore regions. However, stomatal uptake from solutions containing 0 or 1.0 ml litre−1 L‐77 was limited or non‐existent. A phenomenon termed ‚adsorptive dilution’︁ is proposed to explain the absence of stomatal infiltration with the 1.0 ml litre−1 formulation. This involves a migration of surfactant from the bulk solution to the expanding droplet surfaces as the droplet spreads. This dilutes the surfactant concentration within the bulk solution, which can in turn increase surface tension.
Using chlorophyll fluorescence induction for a quantitative detoxification assay with metribuzin and chlorotoluron in excised wheat (Triticum aestivum and Triticum durum) leaves
Authors: Ducruet Jean‐Marc , Sixto Hortensia , Garcia‐Baudin José‐María
Published: November 2006

Chlorophyll fluorescence induction was used as a probe to detect herbicide detoxification in tolerant or susceptible wheat cultivars. Experimental conditions have been carefully examined for establishing detoxification kinetics of chlorotoluron and metribuzin, two photosystem‐II‐inhibiting herbicides. After a root treatment, leaves were cut, placed in glass tubes and maintained in the dark. The fluorescence induction rise was examined repeatedly and detoxification kinetics were established from these data for the same position on the individual leaves. The herbicide‐dependent fluorescence rise decreased within hours in chlorotoluron‐tolerant but not in susceptible Triticum aestivum cultivars. In contrast, no significant reversion could be detected after metribuzin application in both tolerant and susceptible cultivars of Triticum durum. Near the fluorescence‐determined half‐inhibition of photosystem II, linear detoxification kinetics were obtained in individual leaves, thus providing an accurate measurement of relative detoxification rates.
The toxicity of brodifacoum wheat bait to the field rodents Microtus guentheri and Meriones tristrami
Authors: Moran Shmuel
Published: November 2006

The toxicity of the anticoagulant brodifacoum to the field rodent species Microtus guentheri (Danford & Alston) and Meriones tristrami Thomas was tested in the laboratory. Brodifacoum 0.05 g kg−1 whole‐wheat bait was offered to the animals without additional food. The LD50 calculated for M. guentheri was 2.28 mg kg−1 body weight. Brodifacoum was found to be more toxic to M. tristrami; the LD50 was c. 0.8–0.9 mg kg−1 body weight. The toxicity data served to plan the doses of bait to be broadcast in the field.
Mobilities of organic compounds in reconstituted cuticular wax of barley leaves: Determination of diffusion coefficients
Authors: Schreiber Lukas , Schönherr Jörg
Published: November 2006

Isolated cuticular wax, obtained from barley leaves, was mixed with 14Clabelled organic chemicals including aromatic pesticides and long‐chain linear alkanes, alcohols and acids. These mixtures were reconstituted from the melt and labelled chemicals were desorbed from the wax by immersing the wax samples in aqueous phospholipid suspensions. Diffusion coefficients (D) of radiolabelled test compounds in the wax were derived from desorption kinetics. Diffusion coefficients ranged from 10−17 to 10−22 m2 s−1 and decreased rapidly with increasing molar volumes of solutes. However, size selectivity of D was much more pronounced with the linear, long‐chain molecules than with the aromatic compounds. It is argued that the two different groups of chemicals (compounds occurring naturally in cuticular waxes vs pesticide molecules) were trapped in different fractions of wax during crystallization from the melt. The normal long‐chain aliphatic compounds appear to be incorporated into the crystalline fraction of the wax, while the cyclic pesticide molecules are confined to the solid amorphous regions. Our data indicate that constituents of cuticular waxes are not immobile. In fact, relatively small linear aliphatic molecules have mobilities that do not differ too much from those of cyclic pesticides. However, the pronounced size selectivity of diffusivities of long‐chain aliphatic compounds causes a rapid decrease in D with increasing chain length. The value of D of hexadecanoic acid was 3.81 × 10−18 m2 s−1 while that of dotriacontane was only 4.07 × 10−22 m2 s−1. Thus, increasing the carbon number by a factor of two resulted in a decrease in mobility by almost four orders of magnitude. Diffusivities of selected pesticide molecules in reconstituted wax were compared with permeances measured using intact barley leaves and were found to be in satisfactory agreement.
Persistence and activity of mexacarbate and its metabolites against spruce budworm larvae
Authors: Helson Blair V. , Sundaram K. M. Somu
Published: November 2006

This study was conducted to determine if metabolites of mexacarbate contribute to its residual toxicity to spruce budworm (Choristoneura fumiferana) larvae. Potted white spruce (Picea glauca) trees were treated with ‘Zectran’ UCZF # 19 at 100 g a.i. ha−1 and kept in a glasshouse. Mexacarbate residues declined by 98–99% within three days and reached non‐detectable levels 10 days after treatment. Mortality of larvae fed on buds from these trees declined more gradually and was still 19–27% when exposed 10 days after treatment. The very low levels of mexacarbate (<0.07 μg g−1) found after three days did not produce such mortality. Gas chromatographic analysis of metabolites in needles revealed that after three days, 4‐methylformamido‐3,5‐xylyl N‐methylcarbamate was present at levels 20–30 times higher than the parent compound. This metabolite was about 50 times less toxic than mexacarbate to larvae when applied topically but was only 7 times less toxic when ingested. Two other methylcarbamate metabolites, the amino, and methylamino analogues were detectable for one day following treatment but not at later time points. They were as toxic as mexacarbate both topically and orally. Based on these findings, the methylformamido analogue could contribute to the residual toxicity of mexacarbate treatments of spruce.
Ionization and sorption of fomesafen and atrazine by soils and soil constituents
Authors: Weber Jerome B.
Published: November 2006

Fomesafen exhibited weakly acidic properties and was titrated spectrophotometrically and determined to have a pKAof 3.0. [14C]fomesafen and [14C]atrazine, as references, were used in slurry‐type sorption studies with H+‐ and Ca2+‐saturated soil organic matter, Ca2+‐saturated montmorillonite clay, Norfolk sandy loan (Typic Paleudult) and Drummer silt loam (Typic Haplaquoll) at suspension pH values of 2.0 to 6.3. Sorption of atrazine was greater than that of fomesafen for the organic matter sorbents but similar for montmorillonite clay and the two soils. Sorption of both herbicides on the Drummer soil was much greater than on the Norfolk soil, due to the higher organic matter content of the former. Decreasing the suspension pH greatly increased sorption of both herbicides by all sorbents. Atrazine sorption was attributed to ionic bonding at low pH and physical bonding at neutral pH. Fomesafen sorption occurred by way of physical forces at near neutral pH and by way of hydrophobic bonding and/or precipitation at low pH. Mobility and bioavailability of the herbicides in soils is expected to be lower at low pH than at high or neutral pH.
Evidence for the enhanced biodegradation of napropamide in soil
Authors: Walker Allan , Parekh Nisha R. , Roberts Steven J. , Welch Sarah J.
Published: November 2006

In laboratory incubations, the time to 50% loss of napropamide was approximately 60; 21 and 8 days in soil treated for the first, second and third time respectively. In a survey of soils from commercial fields, there was evidence that enhanced biodegradation of the compound had been induced by normal field applications—in some soils by a single previous treatment. Confirmation of the observations of rapid rates of loss in pre‐treated soil was obtained in experiments with three formulations of napropamide. The rate of degradation in enhanced soils was unaffected by treatment of the soils with the antifungal antibiotic cycloheximide, but was inhibited by the antibacterial antibiotic chloramphenicol. Mixed bacterial cultures able to degrade the herbicide were obtained from three rapid‐degrading soils by enrichment culture. Isolates from two of them were able to degrade the herbicide in pure culture. These bacteria have, as yet, not been characterised.
Studies on a mixed bacterial culture from soil which degrades the herbicide linuron
Authors: Roberts Steven J. , Walker Allan , Parekh Nisha R. , Welch Sarah J. , Waddington Martin J.
Published: November 2006

A stable mixed bacterial culture which degrades the herbicide linuron was isolated from soil by enrichment with linuron in a liquid mineral medium. Radio‐respirometry studies showed that the culture mineralised linuron completely. No intermediate degradation products were detected in the medium. The culture was able to utilise linuron as a source of both nitrogen and carbon and was also able to degrade the related herbicides monolinuron and chlorbromuron and the possible intermediate degradation products of linuron: 3,4‐dichlorophenyl‐l‐methylurea, 3,4‐dichlorophenylurea and 3,4‐dichloroaniline. The culture was unable to degrade the 1,1‐dimethyl substituted ureas monuron, diuron or metoxuron. The culture contained Gram‐negative aerobic rods, and Gram‐positive aerobic non‐spore‐forming rods and cocco‐bacilli. Of 124 isolates from the mixed culture, none degraded linuron in pure culture, indicating that a consortium of organisms is involved. Further investigation suggested that Pseudomonas spp. were important components of the population responsible for degradation.
Regulatory problems associated with natural products and biopesticides
Authors: Plimmer Jack R.
Published: November 2006

For registration, the United States Environmental Protection Agency (USEPA) separates pesticides into conventional chemical pesticides and biochemical and microbial pesticides. Natural products generally fall into the latter category. The USEPA has specified the test requirements for registration in the United States in the guidelines for registration of biorational pesticides (Subdivision M of 40 CFR Part 158).

A discussion of the regulatory issues requires some reference to the accompanying scientific developments. The potential application of chemicals that affect insect behavior and development appeared an extremely promising approach to the reduction of adverse environmental and health impacts associated with many conventional pesticides. In addition to these benefits, the new biopesticides generally affected a very specific range of target species. However, although juvenile hormones and semiochemicals offer exciting new approaches to pest control, and are potentially valuable components of pest management strategies, acceptance of these techniques has been slow.

Commercial development has been difficult for several reasons. Regulatory requirements may appear burdensome. Unconventional pest‐control technologies may call for special formulations or application equipment. It may not be easy to establish the efficacy of non‐lethal potential techniques. Investigators who derive funds from the public sector may have neither responsibility nor resources to carry the technology beyond the experimental stage. Because most activities in this field have been heavily research‐oriented, few workers have possessed the additional resources to obtain safety data or data to satisfy regulatory requirements.

Difficulties in preparing and administering guidelines for registration of biopesticides lie in the novelty of the pest control agents and the diversity of the techniques involved in their effective use. Rapid advances in molecular biology and other disciplines continually strain the capabilities of regulators who are responsible for making safety assessments regarding pest‐control agents. Although regulatory authorities are familiar with conventional pesticides, safety assessment of biopesticides calls for totally different approaches.
Diversity of microbial products—discovery and application
Authors: Porter Neil , Fox Frances M.
Published: November 2006

Natural products derived from micro‐organisms, plants and animals possess inherent biological properties and are, therefore, an excellent source of lead chemicals on which to base synthesis programmes employing rational design techniques. Only a fraction of the fungal kingdom has been screened systematically for novel metabolites despite their suspected potential. Moreover, the fungi are generally manipulable in laboratory culture systems and, because of their developmental versatility, they offer tremendous potential as sources of novel metabolites. Primary assay systems based on biochemical targets provide an effective means of screening microbial products; such assay systems also efficiently support chemical purification of lead activities and rapid elucidation of new chemical templates.
Distribution of fenvalerate and permethrin residues on cattle hair following variable application rates of impregnated ear tags
Authors: Mwangala Felix S. , Sarna Leonard P. , Galloway Terry D. , Webster G. R. Barrie
Published: November 2006

Fenvalerate and permethrin residues on hair of groups of cattle that received either two tags per adult animal or one tag for every other adult animal were determined using gas chromatography over a three‐month period in 1987 and 1988. Cattle with two tags had consistently higher residues than cattle with one tag. This difference was statistically significant (P < 0.05) in the first month for residues on the head and in the first two weeks for residues from the body in 1987. Residues on cattle with one tag and without a tag in the same herd were similar (P > 0.05) on each sampling day on all regions. Residues on the hair from the head of cattle with two tags were greater than on the body and rump (P < 0.05) during the first 28 days. Residues found on hair on days 14 and 84 following tag application declined by 80–86% on the head, 73–78% on the body, and 36–86% on the rump. Isomeric compositions of fenvalerate (range 51–61% SR, RS: 39–49% SS, RR) and permethrin (range 61–67% trans: 33–39% cis) were consistent during the study. Rainfall reduced residues on hair.
The current status of insecticide resistance in Musca domestica in England and Wales and the implications for housefly control in intensive animal units
Authors: Chapman Paul A. , Learmount Jane , Morris Alan W. , McGreevy Paul B.
Published: November 2006

Following the 1984–85 housefly (Musca domestica L.) resistance survey, a similar survey was carried out between January 1990 and April 1992 in order to monitor changes in UK housefly resistance. Samples of fly populations were collected from 35 farms throughout England and Wales. Dose‐response data were obtained by topical application and feeding test methods. For both methods the knockdown (KD) after 48 h was used for all the dose‐response comparisons. The ranges of resistance factors for the topical application method were for methomyl, 1·6–20·0 at KD50 and 4·5–34·4 at KD95; for azamethiphos, 2·5–58·5 at KD50 and 5·0–2604 at KD95; for pyrethrins+piperonyl butoxide, 1·2–9·6 at KD50 and 1·6–14·7 at KD95; and for permethrin, 2·2–118·8 at KD50 and 4·3–200·0 at KD95. The ranges of the resistance factors for the feeding tests were for methomyl, 1·2–56·1 at KD50 and 3·1–80·0 at KD95, and for azamethiphos, 3·9–125·0 at KD50 and 4·4–380·0 at KD95. The means of resistance factors for all of the insecticides showed increases over those obtained in a previous survey carried out in 1984–85. The significance of the results for housefly control in intensive animal units in the UK is discussed.
Selective complexometric determination of glyphosate and related compounds
Authors: Répási János
Published: November 2006

A complexometric method has been developed for the selective determination of glyphosate and related compounds. The method is based upon the different pH‐dependence of tridentate and tetradentate ligand‐metal complex stabilities. Glyphosate, the tridentate ligand forms a stable copper complex at pH ≥ 8 only, whereas N‐carboxymethyl‐N‐phosphonomethylglycine and N,N‐bis(phosphonomethyl)glycine, the tetradentate ligands, form sufficiently stable bismuth complexes even at low pH. The method, therefore, consists of aliquot titrations in basic and acidic media, using metal ion titrant solutions.

The first aliquot containing N‐(phosphonomethyl)glycine plus N‐carboxymethyl‐N‐phosphonomethylglycine or N,N,‐bis(phosphonomethyl)glycine is titrated with bismuth volumetric solution at pH 1.8–2–5 in the presence of methylthymol blue indicator. Quantities of the tetradentate ligands can be calculated from the bismuth consumption. The second aliquot is titrated with copper volumetric solution at pH 8–10, in the presence of murexide indicator. The content of glyphosate can be calculated from the difference between the copper and bismuth consumptions. Efficacy of the method is verified by analyses of standard mixtures and industrial samples.
Synergism between EBI fungicides and a pyrethroid insecticide in the honeybee (Apis mellifera)
Authors: Pilling Edward D. , Jepson Paul C.
Published: November 2006

The synergistic effect of a range of ergosterol‐biosynthesis‐inhibiting (EBI) fungicides and a pyrethroid insecticide was studied in the honeybee (Apis mellifera L.). Various EBI fungicides were combined separately with the pyrethroid lambda‐cyhalothrin at ratios derived from their recommended application rates to represent tank‐mixing in the field. The mixture was then applied topically to the thorax of honeybees, and mortality assessed 24 h post‐treatment. All the fungicides tested increased the toxicity of lambda‐cyhalothrin to honeybees. The fungicide propiconazole was found to have the strongest synergistic effect, decreasing the LD50 of lambda‐cyalothrin from 68.0 ng bee−1 to 4.2 ng, thus having a synergistic ratio of 16.2. Hazard ratios were calculated for lambda‐cyhalothrin and fungicide mixtures using a recommended application rate of 7.5 g a.i. ha−1. The hazard ratio for lambda‐cyhalothrin alone was 110, but when mixed with fungicide synergists, the hazard ratio ranged from 366 with flutriafol to 1786 with propiconazole. A blank formulation of a fungicide (without the active ingredient prochloraz) had little effect on the toxicity of lambda‐cyhalothrin, indicating that it is primarily the fungicide active ingredient that is responsible for the synergistic effect. The results are discussed in terms of the potential hazard posed by pesticide synergism to honeybees in the field.
Uptake and metabolism of [14C]aspartate in barley leaves infected with powdery mildew
Authors: Jackson Samantha A. L. , Baldwin Brian C. , Walters Dale R.
Published: November 2006

Infection of barley with powdery mildew altered the uptake and metabolism of [14C]aspartate in first leaves. Uptake was greater in infected leaves 2 h after feeding, but was reduced thereafter. Aspartate was more rapidly metabolised in infected leaves than in controls, probably to homoserine and threonine. The fungus took up aspartate, homoserine and threonine from the plant, but these were apparently not further metabolised over the experimental period. This suggests that barley can metabolise aspartate, probably forming homoserine. threonine and lysine, while such metabolism does not occur in the powdery mildew fungus. This would confirm the presence of the diaminopimelic acid pathway for lysine biosynthesis in barley and its absence from Erysiphe graminis f. sp. hordei Marchal.
The determination of glyphosate in soils with moderate to high clay content
Authors: Spann Kelvin P. , Hargreaves Phillip A.
Published: November 2006

An improved method for the quantitative analysis of the herbicide glyphosate [N‐(phosphonomethyl)glycine] in soils containing moderate to high clay content is described. Critical evaluations of previously published methods have indicated that recoveries of glyphosate from soils with high clay content are often low. Where acceptable recovery estimates have been reported, these methods also report increased interferences and rarely include soils with clay content exceeding 30%.

The proposed method was developed and characterized using six soils of different clay content (25–87% clay), with other physical and chemical properties as described. Recoveries of glyphosate from the soils were determined after duplicate extractions with 0.1 M potassium hydroxide. Clean‐up of soil extract solutions was by cation‐exchange column chromatography. Subsequent quantitation was by HPLC with post‐column oxidation, followed by derivatization using OPA‐MERC with fluorometric detection. No interferences were detected.

Recovery estimates for each fortified sample were determined over a concentration range (0.56–11.25 mg glyphosate kg −1 ) with all recoveries being greater than 80%. Detection limit for glyphosate in soil was 0.04 mg kg −1, and instrument response was linear for solutions up to 50.0μg glyphosate ml −1. Reproducibility relative confidence interval, for a single sample analysis, was determined as.
Influence of oil droplet size on the toxicity of bifenthrin on cotton to tobacco budworm (Heliothis virescens)
Authors: Womac Alvin R. , Mulrooney Joseph E. , Scott William P. , Williford Julius R.
Published: November 2006

Sprays of bifenthrin and paraffinic oil mixtures were applied to cotton leaves (Gossypium hirsutum L.) to investigate droplet size effects on the mortality of Heliothis virescens (F.). An air‐assisted nozzle applied mixtures at 9.4 litre ha −1 spray rate with volume median diameters (VMD) of 96 and 337 μm, as verified with a Malvern laser diffraction analyzer. An hour after spraying, susceptible 3rd‐instars walked for 2‐min through wet droplets of spray mixtures applied at bifenthrin rates of 22, 45, 67, 90. and 112 g a.i. ha −1. Mortality was assessed at 21, 26, 45, 50, 74, and 117h after exposure. Final mean mortality was affected (P =0.01) by bifenthrin rate and droplet size. Bifenthrin applied in 337 μm VMD droplets caused 75.8% mortality, whereas 96‐μm VMD droplets resulted in a mortality of 67.9%. Also, the 337 μm VMD droplets killed larvae in 13% less time than the 96μm VMD droplets, based on analysis (P =0.01) using the mean elapsed time till death as the dependent factor.
Biochemical and physiological targets for miticides
Authors: Dekeyser Mark A. , Downer Roger G. H.
Published: November 2006

The biorational design of new miticides requires an understanding of the biochemistry and physiology of mites. This review considers the interaction and impact of existing miticides with the cuticle, nervous system, growth and development, metabolism, feeding and behaviour and assesses the potential of these as possible targets for miticide development. Considering the sites of action of some of the major miticides, GABAergic and octopaminergic transmission, and oxidative phosphorylation are attractive targets for further miticide development.
Interconversion of stereoisomers of endosulfan on chickpea crop under field conditions
Authors: Mukherjee Irani , Gopal Madhuban
Published: November 2006

The pure individual stereoisomers of endosulfan, alpha‐endosulfan and beta‐endosulfan, were applied as emulsifiable concentrates to chickpea crop at the rate of 175 g a.i. ha −1 and 50 g a.i. ha −1, respectively. The dissipation rate of these isomers revealed that alpha‐endosulfan interconverted to beta‐endosulfan in minor quantities, while it was converted into endosulfan sulfate on chickpea leaves in significant amounts. On application, beta‐endosulfan was converted to endosulfan sulfate and alpha‐endosulfan in relatively smaller amounts. The study indicates that the beta stereoisomer of endosulfan is more persistent because it is resistant to interconversion and metabolic change.
Synthesis and herbicidal activity of isoxazole‐substituted 1‐aminoethylphosphonates and 1‐hydroxyethylphosphonates
Authors: Wielkopolski Witold , Śmieszek Robert , Witek Stanislaw , Dabrowski Andrzej , Wieczorek Piotr , Lejczak Barbara , Kafarski Pawel
Published: November 2006

Isoxazole‐substituted 1‐aminoethyl‐ and 1‐hydroxyethyiphosphonates were synthesized by a multi‐step procedure and were screened for herbicidal activity against Lepidium sativum L. and Cucumis sativus L. All the synthesized compounds exhibited notable herbicidal activity.
Monitoring of resistance of insecticides in house fly (Musca domestica) populations in hungary
Authors: Pap László , Farkas Róbert
Published: November 2006

Samples of 24 house fly (Musca domestica L.) populations were collected from animal farms in Hungary in 1990 and kept in the laboratory to determine their susceptibility to different types of insecticide: organochlorines, organophosphates, carbamates, pyrethroids, macrocyclic lactone and insect growth regulators.

The adulticides were tested with topical bioassay in all 24 populations, the larvicides were studied with treated larval medium in 16 populations. The data were expressed as LD50 and LC50 values (ng fly −1 and mg kg −1 larval medium respectively).

The percentages of populations which had resistance ratios > 10 at LD50 or LC50 were: 63% to DDT, 50% to methoxychlor, 13% to lindane, 83% to malathion, 63% to trichlorfon, 4% to propetamphos, 96% to dioxacarb, 46% to propoxur, 4% to methomyl, 13% to pyrethrum, 96% to bioresmethrin, 63% to permethrin, 58% to cypermethrin, 79% to SK‐80, 79% to deltamethrin, 38% to invermectin, 0% to diflubenzuron, 0% to cyromazine.

Correlation analysis showed a high degree of positive correlation among the adulticides except for ivermectin, bioresmethrin and SK‐80. No cross‐resistance was found between the larvicides and the conventional adulticides.

Differences of insecticide resistance levels among the populations surveyed were studied by principal component and factor analysis. A fairly good relationship between resistance status and control practices used on farms was revealed. The populations originating from those farms where the application of adulticides had been frequent or regular and where high resistance was shown to most chemicals could be separated from the others.
The role of metabolic enzymes in insecticide‐resistant colorado potato beetles
Authors: Wierenga Joel M. , Hollingworth Robert M.
Published: November 2006

Several metabolic enzymes were assayed in susceptible and insecticide‐resistant (R‐mfo and R‐AchE) strains of the Colorado potato beetle (Leptinotarsa decemlineata Say). We compared the activities of esterases, glutathione transferases and mixed function oxidases, and measured in‐vivo metabolism of carbofuran to determine the contributions of metabolic factors to the observed resistance. There were no substantial differences between strains in α‐ or β‐naphthylacetate hydrolysis, or in glutathione transferase activity. Compared to the susceptible strain, the R‐mfo strain showed 4‐fold higher activity in both ethoxyresorufin‐O‐dealkylase, and pentoxyresorufin‐O‐dealkylase activity. The R‐AChE strain had a 1.5‐fold higher level of ethoxyresorufin‐O‐dealkylase activity. Correspondingly, the in‐vivo metabolism of carbofuran was highest in the R‐mfo strain, and the R‐AChE strain was slightly higher than the susceptible strain. These results are discussed in relation to other resistance mechanisms which we have examined in these strains.
Enantioselectivity of protoporphyrinogen oxidase‐inhibiting herbicides
Authors: Nandihalli Ujjana B. , Duke Mary V. , Ashmore John W. , Musco Vincent A. , Clark Robert D. , Duke Stephen O.
Published: November 2006

Protoporphyrinogen oxidase (Protox) was inhibited stereoselectively by three pairs of enantiomers belonging to diphenyl ether (DPE) and pyrazole phenyl ether (PPE) herbicide classes. The (R) enantiomers were 10‐ to 44‐fold more active than the (S) enantiomers as inhibitors of Protox from barley etioplasts. Similarly, the (R) enantiomers caused green barley tissue to accumulate greater amounts of porphyrins and caused greater tissue damage than the (S) enantiomers. The (R) enantiomers competed more successfully with [ 14 C]acifluorfen than the (S) enantiomers for the binding sites on Protox. In the PPE class, the in‐vitro and in‐vivo activity differences were wider in the isopropyl pairs than in the n‐propyl pairs. The DPE enantiomers were tested on ten dicotyledonous and six monocotyledonous weed species and ten crops for weed control and crop safety. In general, neither enantiomer had pre‐emergence activity on monocotyledons, but the (R) enantiomer provided some monocotyledonous weed control when applied post‐emergence. On dicotyledons, the (R) enantiomer provided excellent pre‐emergence control, whereas the (S) enantiomer was inactive. The (R) enantiomer caused no injury to corn, cotton, peanuts, rice, sorghum, or soybeans applied pre‐emergence, but it severely injured crops when applied post‐emergence. There was a positive correlation between the activities of the compounds at the molecular, cellular and whole plant levels. The only molecular property differences found to account for differences in activity between members of chiral pairs were steric parameters.
Transformation rates of ortho‐substituted thiophene and benzene carboxylic esters: Application to thifensulfuron‐methyl and metsulfuron‐methyl herbicides
Authors: Bastide Jean , Badon Robert , Cambon Jean‐Pierre , Vega Danielle
Published: November 2006

The rate constants for soil degradation and alkaline hydrolysis of two herbicides, metsulfuron‐methyl and thifensulfuron‐methyl, have been determined. In order to explain the difference in behaviour of the two compounds, the chemical and enzymatic hydrolysis of some ortho‐substituted methyl benzoates and methyl 3‐substituted thiophene‐2‐carboxylates were studied. The data are consistent with a difference in polar and steric effects of the substituents in benzene and thiophene derivatives.