Effects of Selected Chemical Pesticides on Agamermis unka (Nematoda: Mermithidae), a Parasite of the Brown Plant Hopper,Nilaparvata lugens

Selected commercial and technical grade pesticides were tested against the egg, preparasite and adult stages of Agamermis unka , a nematode parasite of the brown planthopper, Nilaparvata lugens . The commercial insecticide, diazinon (LC = 0.37 ppm), was most toxic to the 50 preparasites, followed by phenthoate (LC = 0.43 ppm), BPMC (LC = 0.44 ppm), IBP 50 50 (LC = 0.46 ppm), cartap hydrochloride (LC = 0.82 ppm) and buprofezin + isoprocarb 50 50 (LC = 1.11 ppm). The least toxic commercial pesticide tested was the fungicide, pencycuron 50 (LC = 2.19 ppm). Out of 12 technical grade insecticides tested, phenthoate, monocrotophos, 50 diazinon and carbofuran (LC = 0.37-0.46 ppm) were highly toxic to the preparasites, followed by 50 buprofezin, BPMC and fenitrothion (LC = 0.74-0.86 ppm). Fenthion, etofenprox, chlorpyrifos, 50 imidacloprid and MIPC (LC = 1.11-2.19 ppm) were the technical grade insecticides least toxic 50 to the preparasites. Most preparasites survived for up to 24 h at the low insecticide concentrations (0.63 and 0.31 ppm). Preparasites that were exposed to BPMC for 24 h at concentrations as high as 5.0 ppm and survived the treatments infected brown planthopper nymphs. Four selected insecticides-chlorpyrifos, BPMC, imidacloprid and carbofuran-had significant adverse effects on A. unka egg hatching. Eggs that were in the insecticide solution for 168 h fared poorly with imidacloprid having the best survival ( > 2% of the eggs hatching at 0.04 ppm). No eggs hatched from the other insecticide treatments. Three selected insecticides, BPMC, imidacloprid and chlorpyrifos, tested against adult A. unka showed that most adults survived the exposure to the insecticides between 0.31 and 2.5 ppm. At 5.0 ppm of BPMC or chlorpyrifos none of the adults survived, whereas with imidacloprid 70% of the adults survived. Egg deposition by the surviving adults was greatly reduced in those treated with the insecticides compared with those in the controls. Imidacloprid had some negative impact on the preparasites' ability to infect BPH nymphs, but it had the least detrimental effect of the insecticides tested on preparasite survival and on the eggs and adults of A. unka .     

Penetration of the eastern subterranean termite into soil treated at various thicknesses and concentrations of Dursban TC and Premise 75

The ability of eastern subterranean termites, Reticulitermes flavipes (Kollar), to penetrate various concentrations and treatment thicknesses ranging from 1.0 to 50.0 mm of Dursban TC and Premise 75 was evaluated in a laboratory bioassay. Termites penetrated only a few millimeters into 500 ppm Dursban TC-treated soil at all thicknesses. As concentration decreased, termite penetration into Dursban TC-treated soil increased with termites generally penetrating completely through 5.0- and 0.5-ppm treatments. Termites penetrated at least 30% into 10-, 25-, and 50-mm thicknesses of 100 ppm Premise 75. Termites generally completely penetrated all concentrations < or = 100 ppm and thicknesses < or = 5 mm. At 7 d, termite mortality was 100% at all treatment thicknesses of Dursban TC at 500 and 50 ppm. At 5.0 and 0.5 ppm Dursban TC, termite mortality ranged from approximately 45 to 98% across all treatment thicknesses. At 100- and 10-ppm concentrations of Premise 75-treated soil, termites suffered > or = 75% mortality. Premise 75 at 1.0 and 0.1 ppm generally killed < or = 50% of the assayed termites at all treatment thicknesses.     

Residual control and lethal concentrations of GF-120 (spinosad) for Anastrepha spp. (Diptera: Tephritidae)

The objective of this study was to determine the relationship between residual time of GF-120 (spinosad) treatment and mortality in three species of Anastrepha Schiner. Concentrations of 96, 72, 48, and 24 ppm were aged on mango leaves under field conditions for 0, 3, 7, 10, 14, 17, and 21 d after application. We found that Anastrepha ludens, A. obliqua, and A. serpentina were highly sensitive to spinosad. The effects of spinosad were not reduced over the 4 d after the initial application, even at a concentration of 24 ppm. Mortality at 14 d after the application of 72 and 96 ppm of spinosad was similar in each of the three fruit fly species. In addition, we found that 24 ppm of spinosad was consumed the most by each species even though no direct relationship between the rate of consumption per female and the dose of the product was observed, in this test, higher consumption of active ingredient was observed at a concentration of 72 ppm, for A. ludens, 48 ppm for A. obliqua, and 96 ppm for A. serpentina. Our results suggest that a spinosad concentration of 72 ppm may effectively control these pests for at least 10 d under field conditions.     

The effect of ethrel on nodulation inPisum sativum L.

Summary Nodulation of inoculated pea plants was severely inhibited when ethrel (2-chloroethane phosphonic acid) was applied to the roots. The inhibition was evident at ethrel concentrations of 2 ppm and above. Ethrel applied to the foliage at 10 ppm also depressed nodulation. At least part of the effect of ethrel on nodulation came from its inhibition of root growth. Nodulation was inhibited on half of a divided root system treated with ethrel, while there was no inhibition on the neighbouring untreated half.     

The effect of an aldehyde biocide on the performance and characteristics of laboratory-scale rotating biological contactors

The effect of an aldehyde biocide, glutaraldehyde, on the treatment efficiency of laboratory-scale rotating biological contactors (RBCs) as well as their component biofilms was studied. Biofilms were established on the RBCs and then exposed to 0-120 ppm glutaraldehyde at a flow rate of 2.5 l x h(-1). The results showed that glutaraldehyde up to 80 ppm did not cause any adverse effect on chemical oxygen demand (COD) removal of the RBC units, microbial activity (ATP content) of biofilms on the RBC disc and viability of the biofilms. Glutaraldehyde at 80 ppm could be almost totally removed by the units regardless of the presence of simple carbon sources. There was at least a fourfold difference in susceptibility of planktonic and sessile bacteria to glutaraldehyde. Cells acclimatized to glutaraldehyde did not increase their capability to degrade normal carbon sources or glutaraldehyde under the conditions used in this study.     

On-line detection of atmospheric formaldehyde by a conductometric biosensor

Atmospheric formaldehyde (CH(2)O) was detected under continuous flow conditions by an on-line system comprising of a wet scrubber for a continuous transfer of the pollutant to an aqueous solution, a micro-reactor containing immobilized formaldehyde dehydrogenase (FDH) and a conductometric transducer. By this system atmospheric formaldehyde concentrations in the range 0.05-2 ppm were detected with a sensitivity of 20 microS/ppm. In this concentration range the immobilized enzyme oxidized all the sampled formaldehyde molecules to formic acid, avoiding cumbersome calibration procedures. The operational stability of the biosensor was at least 3 months, working continuously 10 h/day at room temperature.     

Biology and control of the sciarid Lycoriella auripila Winn. (Diptera: Lycoriidae) in mushroom culture

The life-history of L. auripila, as a pest of mushrooms, is outlined and an explanation is given of the different types of damage caused. The most satisfactory control is based on the incorporation of insecticides in compost at spawning. Emulsions of chlorfenvinphos and diazinon at 50 ppm are lethal to young larvae for at least 7 weeks but granular formulations of the former must be applied at 100 ppm to achieve comparable results. Drenches of 0–01% malathion, applied at about 40 gal/1000 ft², are effective against larvae in the casing.     

Antimicrobial Activity of Essential Oil Components Against Potential Food Spoilage Microorganisms

The antimicrobial activity of six essential oil components against the potential food spoilage bacteria Aeromonas (A.) hydrophila, Escherichia (E.) coli, Brochothrix (B.) thermosphacta, and Pseudomonas (P.) fragi at single use and in combination with each other was investigated. At single use, the most effective oil components were thymol (bacteriostatic effect starting from 40 ppm, bactericidal effect with 100 ppm) and carvacrol (50 ppm/100 ppm), followed by linalool (180 ppm/720 ppm), α-pinene (400 ppm/no bactericidal effect), 1,8-cineol (1,400 ppm/2,800 ppm), and α-terpineol (600 ppm/no bactericidal effect). Antimicrobial effects occurred only at high, sensorial not acceptable concentrations. The most susceptible bacterium was A. hydrophila, followed by B. thermosphacta and E. coli. Most of the essential oil component combinations tested showed a higher antimicrobial effect than tested at single use. Antagonistic antimicrobial effects were observed particularly against B. thermosphacta, rarely against A. hydrophila. The results show that the concentration of at least one of the components necessary for an antibacterial effect is higher than sensorial acceptable. So the use of herbs with a high content of thymol, carvacrol, linalool, 1,8-cineol, α-pinene or α-terpineol alone or in combination must be weighted against sensorial quality.     

Mechanism of the binding of Z-L-tryptophan and Z-L-phenylalanine to thermolysin and stromelysin-1 in aqueous solutions

The chemical shift of the carboxylate carbon of Z-tryptophan is increased from 179.85 to 182.82 ppm and 182.87 ppm on binding to thermolysin and stromelysin-1 respectively. The chemical shift of Z-phenylalanine is also increased from 179.5 ppm to 182.9 ppm on binding to thermolysin. From pH studies we conclude that the pK(a) of the inhibitor carboxylate group is lowered by at least 1.5 pK(a) units when it binds to either enzyme. The signal at ~183 ppm is no longer observed when the active site zinc atom of thermolysin or stromelysin-1 is replaced by cobalt. We estimate that the distance of the carboxylate carbon of Z-[1-(13)C]-L-tryptophan is ≤3.71? from the active site cobalt atom of thermolysin. We conclude that the side chain of Z-[1-(13)C]-L-tryptophan is not bound in the S(2)' subsite of thermolysin. As the chemical shifts of the carboxylate carbons of the bound inhibitors are all ~183 ppm we conclude that they are all bound in a similar way most probably with the inhibitor carboxylate group directly coordinated to the active site zinc atom. Our spectrophotometric results confirm that the active site zinc atom is tetrahedrally coordinated when the inhibitors Z-tryptophan or Z-phenylalanine are bound to thermolysin.     

Studies on zinc- and cadmium-bound proteins in bovine kidneys by biochemical and neutron activation techniques

Bovine kidneys were found to contain about 78 ppm Zn and 0.78 ppm Cd. Approximately 45% of Zn and 60% of Cd were present in the cytosol fraction. More than 95% of these two metals were bound to macromolecules. Both Zn- and Cd-protein complexes were observed to be stable between pH 7 and 10.5. Separation and characterization of these proteins were carried out using several chromatographic and electrophoretic techniques in conjunction with instrumental neutron activation analysis (INAA). The results showed the presence of at least four Zn-binding proteins with mol wt>300,000, 260,000, 89,000, and 27,000 and at least three Cd-binding proteins of mol wt>300,000, 32,000, and 13,000.     

Antifeedant,larvicidal and growth inhibitory activities of fractions from Clerodendrum phlomidis Linn. F. against bhendi fruit borer Earias vittella Fab

Antifeedant, larvicidal and growth inhibitory activities of 12 fractions from chloroform extract of Clerodendrum phlomidis Linn. F. were evaluated against Earias vittella. Among the fractions, fraction 5 showed promising antifeedant activity of 86.94% at 1000 ppm followed by 500 ppm concentration with the least LC₅₀ and LC₉₀ values of 120.15 and 1027.92 ppm, respectively, with significant Chi-square values. Fraction 5 had maximum larvicidal activity of 86.38% at 1000 ppm concentration with the least LC₅₀ and LC₉₀ values of 245.42 and 1010.99 ppm, respectively, with significant Chi-square value of 51.33 (p ≤ 0.05). Fractions 5 and 6 reduced the adult emergence to 0% at 1000 ppm concentration. According to our knowledge, this is the first report of fractions from C. phlomidis for activity against E. vittella. The study clearly suggests that the fraction from C. phlomidis could be used to develop a new botanical formulation to manage economically important pests.     

Two generation reproduction study of ethylbenzene by inhalation in Crl-CD rats

BACKGROUND: This study was conducted to evaluate the potential adverse effects of ethylbenzene (EB) on reproductive capability from whole-body inhalation exposure of F0 and F1 parental animals. METHODS: Four groups of Crl:CD(SD)IGS BR rats (30/sex/group for F0 and 25/sex/group for F1) were exposed to 0, 25, 100, and 500 ppm EB for 6 hr/day for at least 70 consecutive days before mating. Inhalation exposure for the F0 and F1 females continued throughout mating, gestation through gestation day (GD) 20, and lactation days (LD) 5-21. On LD 1-4, females received EB in corn oil via oral gavage at dose levels of 26, 90, and 342 mg/kg/day (divided into three equal doses, approximately 2 hr apart), as calculated from a physiologically-based pharmacokinetic (PBPK) model to provide similar maternal blood area-under-concentration (AUC) as provided by inhalation. Pups were weaned on postnatal day (PND) 21 and exposure of the F1 generation started on PND 22. Estimates of internal exposure were determined by measuring EB concentrations in blood collected from F1 dams (4/group) and their culled pups 1 hr after the last gavage dose on PND 4. On PND 22, blood was collected from these same F1 dams and their weanlings for EB analysis 1 hr after a 6-hr inhalation exposure. The remainder of the F2 generation was not directly exposed. RESULTS: EB exposure did not affect survival or clinical observations. Male rats in the 500 ppm group in both generations gained weight more slowly than the controls. There were no indications of adverse effects on reproductive performance in either generation. Male and female mating and fertility indices, pre-coital intervals, spermatogenic endpoints, ovarian follicle counts, reproductive organ weights, lengths of estrous cycle and gestation, live litter size, pup weights, developmental landmarks, and postnatal survival were unaffected. No adverse exposure-related macroscopic pathology was noted at any level. CONCLUSIONS: Increased liver weights were found in the animals exposed to 500 ppm. F1 maternal whole blood EB concentrations of 0.49, 3.51, or 18.28 mg/L were found 1 hr after administration of a composite oral dose of 26, 90, or 342 mg/kg/day, respectively, but no detectable EB was found in blood samples of their F2 PND 4 culled pups. F1 maternal mean whole blood EB levels 1 hr after a 6-hr inhalation exposure on postpartum day (PPD) 22 was 0.11 mg/L (25 ppm), 0.56 mg/L (100 ppm), and 11 mg/L (500 ppm). For the offspring exposed with their dams on PND 22, F2 pup blood EB concentrations ranged from 0.017-0.039 mg/L (25 ppm), 0.165-0.465 mg/L (100 ppm), and 8.82-15.74 mg/L (500 ppm). Because decreased weight gain in the 500 ppm males was transient and no histopathological changes were associated with the increased liver weights in the 500 ppm male and female groups, these changes were not considered adverse. Therefore, for parental systemic toxicity, 100 ppm was considered a NOEL and 500 ppm a NOAEL in this study. The 500 ppm exposure concentration was considered a NOAEL for F0 and F1 reproductive toxicity and offspring developmental endpoints.     

Biological inactivation of adhering Listeria monocytogenes by listeriaphages and a quaternary ammonium compound.

The use of listeriaphages as a means of disinfecting contaminated stainless-steel and polypropylene surfaces was investigated. Surfaces artificially contaminated with L. monocytogenes 10401 and 8427 were sanitized with suspensions of listeriaphages (H387, H387-A, and 2671), all belonging to the Siphoviridae family. Phage suspensions at concentrations of up to 3.5 x 10(8) PFU/ml were at least as efficient as a 20 ppm solution of a quaternary ammonium compound (QUATAL) in reducing L. monocytogenes populations. A synergistic activity was observed when two or more phages were used in combination and when phages were suspended in QUATAL. The biological activity of the three phages was not affected by QUATAL concentrations of 50 ppm and a contact time of 4 h.     

Screening of Costa Rican Trichilia species for biological activity against the larvae of Spodoptera litura (Lepidoptera: Noctuidae)

Crude methanolic extracts made from the twigs of 39 plant samples from six species of Trichilia collected in Costa Rica, were incorporated into artificial diet and fed to neonate Spodoptera litura larvae. All six plant species tested significantly reduced larval growth after 7 and 10 days. The most active species was T. americana, reducing growth, on average, to 3.9% of control at 1000ppm fresh weight. The least active, on average, was T. glabra. A twig extract of T. americana proved to be more active than wood, bark or leaf extracts, with the twig extract reducing growth of S. litura larvae by 50% (EC(50)) at a dietary concentration of 17.2ppm. When T. americana wood extract was incorporated into artificial diet (10, 25, 50 and 75ppm) and fed to S. litura larvae throughout larval development, growth was slowed and the final weight of pupae and adults was reduced. At higher extract concentrations (50 and 75ppm) larvae entered one or two supernumerary instars before pupation occurred. This was shown to be due to both starvation and to post-ingestive activity of the extract.     

Mobility of lipid in complexes of amylose–fatty acids by deuterium and C solid state NMR

Palmitic and lauric acid complexes with amylose were studied by solid state methods: ¹³C CP/MAS NMR, deuterium NMR, X-ray powder diffraction and differential scanning calorimetry (DSC). The crystalline amylose complexes were found to be in a V-type sixfold single chain helix. The melting points of the complexes were over 100°C, at least 40–50°C higher than the melting points of the free fatty acids. CP/MAS ¹³C NMR spectra revealed two resonance peaks at 33.6 and 32.4 ppm for the palmitic acid, which were assigned as free and complexed fatty acid, respectively. A single resonance peak at 32.4 ppm was found for the lauric acid and assigned to the complex. The chemical shift of 32.4 ppm for the complexed fatty acids suggests a combined trans and gauche conformation for the fatty acid chain in the complex. T₁ relaxation measurements on the two palmitic acid resonances show different behavior: a very slow relaxation for the 33.6 ppm and a much faster relaxation (1.2 s) for the 32.4 ppm resonances. The latter was similar to the relaxation of the single resonance of the lauric acid (1.1 s). Temperature dependent deuterium spectra of the amylose–lauric acid and amylose–palmitic acid complexes suggest a complete complexation for the amylose–lauric acid, whereas the amylose–palmitic acid complex is partially disassociated by the thermal treatment. Based on the overall data, a partially disordered model is proposed: an imperfect helix with the fatty acid partly inside and partly out, depending on crystallization conditions and the necessity of placing the carboxyl head outside the V-helix.     

Studies on the persistence and effects on soil fauna of some soil-applied systemic insecticides

Granular formulations of menazon, phorate and thionazin were applied to a sandy loam soil (pH = 6·1)in April and May as in-row treatments at commercial rates. They were also broadcast and mixed into the top 4 in of soil at concentrations (10 and 250 ppm of dry soil) which simulated the local in-row concentrations in areas large enough for sampling. Bioassays showed that 50 % of phorate, thionazin and menazon equivalents had disappeared in about 68, 57 and 23 days respectively from soil treated with 10 ppm of the insecticides. Small residues of the 250 ppm treatments still remained 2 years later. The initial rate of loss of activity of thionazin applied at 250 ppm was much slower than from a 10 ppm application whereas the activities of 250 and 10 ppm of menazon disappeared at similar rates. Phorate at 250 ppm killed almost all earthworms, Collembola, Acarina, free-living saprophytic and parasitic nematodes and Protozoa; 10 ppm phorate and 250 ppm of menazon also killed almost all Collembola and Acarina but the menazon was relatively harmless to earthworms. Collembola and mite populations began to increase when residues of phorate and menazon equivalents had decreased to about 2 and 20 ppm respectively, and after 15 months they were similar to those in untreated plots. The broadcast treatments initially decreased the rate of breakdown of leaf discs put in the soil but, after about 4 weeks, breakdown increased, sometimes above that in untreated plots. This was associated with a large increase in numbers of Enchytraeidae which were apparently unaffected by the insecticides. Four months after application, 1 lb/acre of phorate and 2 lb of menazon applied in seed drills 2 ft apart were not affecting Collembola in soil between the rows but were still decreasing the numbers within them. In -row phorate distributed along a 1·5 in diameter band of soil, 3 in deep, killed Collembola 3 in on either side but not 6 in away. It did not spread upwards in toxic quantities, but after rainfall, sufficient to kill Collembola leached at least 3 in downwards. We conclude that commercial in-row applications of chemicals like phorate are most unlikely to harm soil fertility, especially as the leaf-litter-destroying function of Collembola and other animals killed by phorate may be taken over by Enchytraeidae.     

Sterilisation of explants and cultures with sodium dichloroisocyanurate

The effectiveness of Sodium dichloroisocyanurate as a disinfectant for micropropagated plants was assessed. Analysis of the microbial flora of micropropagated plants showed a wide range of bacteria with predominantly Pseudomonas, Xanthomonas and Actinomycetes. Sodium dichloroisocyanurate was highly stable both as preprepared tablets and as solutions maintained at room temperature. Sterilisation of a range of plants which were heavily contaminated with bacteria was examined. Phytotoxicity was generally low and restricted to old leaves and cut surfaces. Solutions of Sodium dichloroisocyanurate were more effective at high concentrations (5000 ppm) than a commercially available bleach for disinfection of shoot cultures. Sodium dichloroisocyanurate was also used at low concentrations (300 ppm) for longer periods (24 h–48 h) to disinfect shoot explants from the field, and was at least as effective for sterilisation as a combination of Mercuric Chloride and Calcium hypochlorite.Abbreviations NaDCC Sodium Dichloroisocyanurate     

The role of carbon dioxide in light-activated hydrogen production by Chlamydomonas reinhardtii

Light-activated hydrogen and oxygen evolution as a function of CO₂ concentration in helium were measured for the unicellular green alga Chlamydomonas reinhardtii. The concentrations were 58, 30, 0.8 and 0 ppm CO₂. The objective of these experiments was to study the differential affinity of CO₂/HCO ₃ ^- for their respective Photosystem II and Calvin cycle binding sites vis-à-vis photoevolution of molecular oxygen and the competitive pathways of hydrogen photoevolution and CO₂ photoassimilation. The maximum rate of hydrogen evolution occurred at 0.8 ppm CO₂, whereas the maximum rate of oxygen evolution occurred at 58 ppm CO₂. The key result of this work is that the rate of photosynthetic hydrogen evolution can be increased by, at least partially, satisfying the Photosystem II CO₂/HCO ₃ ^- binding site requirement without fully activating the Calvin-Benson CO₂ reduction pathway. Data are presented which plot the rates of hydrogen and oxygen evolution as functions of atmospheric CO₂ concentration in helium and light intensity. The stoichiometric ratio of hydrogen to oxygen changed from 0.1 at 58 ppm to approximately 2.5 at 0.8 ppm. A discussion of partitioning of photosynthetic reductant between the hydrogen/hydrogenase and Calvin-Benson cycle pathways is presented.Abbreviations PET photosynthetic electron transport - PS Photosystem     

Tolerance of wheat and pea to boron in irrigation water

In a micro-plot experiment 1.5 ppm boron in the irrigation water was toxic for wheat. Its concentration in the soil solution increased to 1.53 ppm and in the plant tissue to 58 ppm. In pea plants 4 ppm B in the irrigation water was toxic with 2.00 ppm soil solution B and 213 ppm tissue B. Nitrogen in both species increased significantly and calcium decreased with the increase in B in irrigation water. The yield of wheat grain declined by 13, 20 and 32 per cent at the 4.0, 6.0 and 8.0 ppm B respectively. The yield of straw and grains of pea declined by 31, 56 and 41, 56 per cent at 6.0 and 8.0 ppm B levels respectively. Thus tolerance to B in irrigation water was between 3.0 and 4.0 ppm for wheat and 4.0 and 6.0 ppm for pea.