Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Koch

  • Aphi craccivora koch
  • Tetranychu urticae koch
  • c. koch
  • craccivora koch
  • urticae koch

  • Terms modified by Koch

  • koch triangle

  • Selected Abstracts

    Ultrastructure and functional features of midgut of an adult water mite Teutonia cometes (Koch, 1837) (Hydrachnidia: Teutoniidae)

    ACTA ZOOLOGICA, Issue 2 2010
    Andrew B. Shatrov
    Abstract Shatrov, A. B. 2010. Ultrastructure and functional features of midgut of an adult water mite Teutonia cometes (Koch 1837) (Hydrachnidia: Teutoniidae). ,Acta Zoologica (Stockholm) 91: 222,232 The midgut of the adult water mite Teutonia cometes (Koch 1837) (Hydrachnidia: Teutoniidae) was investigated by means of transmission electron microscopy and on semi-thin sections. The midgut is represented by a blind sac composed of the narrow ventriculus, two proventricular lateral diverticula and three pairs of postventricular caeca. A single-layered epithelium consists of one type of endodermal digestive cells of quite different shape and size, which may form protrusions into the midgut lumen. The large nuclei are frequently lobed and contain one to three nucleoli. The apical cell membrane forms short scarce microvilli, between their bases the pinocytotic vesicles of unspecific macropinocytosis as well as the narrow pinocytotic canals are formed and immersed into the cell. The intracellular digestion of the food ingested into the midgut after extraintestinal digestion is predominant. The pinocytotic vesicles fuse with small clear vesicles of proposed Golgi origin to form secondary lysosomes. The digestive cells also contain small amounts of rough endoplasmic reticulum, variously structured heterolysosomes, residual materials in the form of both the small electron-dense bodies and the large variously granulated substances, reserve nutritive materials such as lipid and glycogen, as well as clear vacuoles. Residual materials are obviously extruded from the cells into the gut lumen. [source]

    Trade-offs in oviposition choice?

    Food-dependent performance, defence against predators of a herbivorous sawfly
    Abstract The sawfly Athalia rosae L. (Hymenoptera: Tenthredinidae) is a feeding specialist on plant species of the Brassicaceae, which are characterised by secondary metabolites, called glucosinolates. The larvae can take up the respective glucosinolates of their hosts and concentrate them in their haemolymph to protect themselves against predators. Oviposition preferences of naďve females were tested for three species, Sinapis alba L., Brassica nigra (L.) Koch, and Barbarea stricta Andrz., and were related to larval performance patterns. Larvae were reared on either one of these plants and it was investigated how host-plant quality influences both the developmental times and growth of larvae (bottom-up) and the defence efficiency against predators (top-down). Innately, almost all adult females avoided B. stricta for oviposition and clearly preferred B. nigra over S. alba. On average, larvae developed best on B. nigra. Female larvae reached similar final body masses on all host-plant species, but males reared on S. alba were slightly lighter. The developmental time of larvae reared on B. stricta was significantly longer than on the other two plants. However, larvae reared on B. stricta were best protected against the predatory wasp Polistes dominulus Christ (Hymenoptera: Vespidae). The wasps rejected these larvae most often, while they attacked larvae reared on S. alba most frequently. Thus, larvae feeding on B. stricta theoretically run a higher risk of predation due to a prolonged developmental time, but in practice they are better protected against predators. Overall, oviposition preferences of A. rosae seem to be more influenced by bottom-up effects on larval performance than by top-down effects. [source]

    Electronically monitored cowpea aphid feeding behavior on resistant and susceptible lupins

    Geoffrey W. Zehnder
    Abstract The feeding behavior of cowpea aphid, Aphis craccivora Koch (Homoptera: Aphididae) was examined on seedlings of narrow leafed lupin, Lupinus angustifolius L., and yellow lupin, L. luteus L., using electronic monitoring of insect feeding behavior (EMIF). Aphid feeding behavior was first compared between resistant (cv. Kalya) and susceptible (cv. Tallerack) varieties of narrow-leafed lupin. Aphids spent significantly more time in non- penetration and stylet pathway activities, and significantly less time in the sieve element phase on Kalya than on Tallerack, suggesting that feeding deterrence is an important component of aphid resistance in Kalya. Aphid feeding on a susceptible yellow lupin variety (cv. Wodjil) was then compared with that on two resistant lines, one (Teo) with high and the other (94D024-1) with low seed alkaloid content. There were no consistent differences in aphid feeding behavior between Wodjil and Teo. Total, mean and percentage sieve element phase times were significantly lower, and total and percentage times in non-phloem phase were greater on 94D024-1 than on Wodjil, suggesting the possibility of phloem-based deterrence in 94D024-1. [source]

    Pollination mutualism between a new species of the genus Colocasiomyia de Meijere (Diptera: Drosophilidae) and Steudnera colocasiifolia (Araceae) in Yunnan, China

    Kohei TAKENAKA
    Abstract A new species of the genus Colocasiomyia de Meijere (Diptera: Drosophilidae) was discovered from inflorescences of Steudnera colocasiifolia K. Koch (Araceae) in Yunnan, China. The new species is described as Colocasiomyia steudnerae Takenaka and Toda, sp. nov., and we investigated the reproductive ecology of both the fly and the plant species. This fly species reproduces in the inflorescences/infructescences of the plant, and depends almost throughout its entire life cycle on the host plant. The fly species is the most abundant flower visitor for S. colocasiifolia and behaves intimately with the flowering events, suggesting that it is the unique and most efficient pollinator for the host plant. Bagging (insect-exclusion) treatment of inflorescences resulted in no fruits. These findings strongly suggest that intimate pollination mutualism has evolved between the fly and the host plant, as are known in other Colocasiomyia flies and Araceae plants. One notable feature of this system is that the new species almost monopolizes the host-plant inflorescence as a visitor, without any cohabiting Colocasiomyia species. In comparison to other cases where two Colocasiomyia species share the same inflorescence and infructescence of Araceae host plants for reproduction by separating their breeding niches microallopatrically between the staminate (upper male-flower) and the pistillate (lower female-flower) regions on the spadix, C. steudnerae exhibits a mixture of stamenicolous and pistillicolous breeding habits. [source]

    Strategies for Improving Tensile Ductility of Bulk Nanostructured Materials,

    Yonghao Zhao
    Abstract The low ductility that is consistently associated with bulk nanostructured (NS) materials has been identified as perhaps the single most critical issue that must be resolved before this novel class of materials can be used in a wide variety of applications. Not surprisingly, a number of published studies, published mostly after 2000, identify the issue of low ductility and describe strategies to improve ductility. Details of these strategies were discussed in review papers published by Koch and Ma in 2005 and 2006, respectively.15,16 In view of continued efforts and recent results, in this paper we describe progress in attempting to address the low ductility of NS materials, after 2006. We first analyze the fundamental reasons for the observed low ductility of bulk NS materials, and summarize early (prior to 2006) attempts to enhance the ductility of bulk NS materials, which often sacrificed the strength. Then, we review recent progress in developing strategies for improving the tensile ductility of bulk NS materials, which involve mainly microstructure modifications, after 2006. Different from early efforts, these new strategies strive to increase the tensile ductility while increasing/maintaining the strength simultaneously. In addition, the influence of tensile testing conditions, including temperature, strain rate, tensile specimen size and geometry, and strain measurement methods, on tensile ductility of NS materials will also be reviewed. Finally, we identify several issues that will require further, in depth analysis in the future. [source]

    Thermogenesis and respiration of inflorescences of the dead horse arum Helicodiceros muscivorus, a pseudo-thermoregulatory aroid associated with fly pollination

    FUNCTIONAL ECOLOGY, Issue 6 2003
    R. S. Seymour
    Summary 1In central Corsica, Helicodiceros muscivorus (Schott ex. K. Koch) produces a protogynous inflorescence that resembles the anal area of a dead mammal and produces a foetid scent during the few hours after sunrise. Flies enter the floral chamber, pollinate the female florets and become trapped until the next morning, when pollen is shed from the male florets and the flies are released. 2The exposed appendix exhibits a strong, unimodal episode of thermogenesis associated with scent production, reaching a maximum of 30 °C at 15 °C ambient temperature. The male florets in the floral chamber are highly thermogenic throughout the second night and generally maintain stable floret temperatures of about 24 °C at ambient temperatures down to 13 °C. 3Maximum respiration rates of the appendix (0·45 µmol CO2 s,1 g,1) and the male florets (0·82 µmol s,1 g,1) may be the highest recorded for plant tissue. 4Thermogenesis of the appendix does not depend on ambient temperature, but that of the male florets increases with decreasing ambient temperature in most cases. However, the pattern of heat production by the males appears related more to time than to ambient temperature, hence the term ,pseudo-thermoregulation'. 5The behaviour and thoracic temperatures of flies emerging from captivity suggests that male floral warming does not enhance their activity. [source]


    INSECT SCIENCE, Issue 3 2003
    Xue-xia Miao
    Abstract To evaluate the role of bacterial symbionts (Buchnera spp.) in the black bean aphids (Aphis craccivora Koch), the aphids were treated with the antibiotic, rifampicin, to eliminate their intracellular symbiotic bacteria. Analysis of protein and amino acid concentration in 7-day-old of aposymbiotic aphids showed that the total protein content per mg fresh weight was significantly reduced by 29%, but free amino acid titers were increased by 17%. The ratio of the essential amino acids was in general only around 20% essential amino acids in phloem sap of broad bean, whereas it was 44% and 37% in symbiotic and aposymbiotic aphids, respectively, suggesting that the composition of the free amino acids was unbalanced. For example, the essential amino acid, threonine represented 21.6% of essential amino acids in symbiotic aphids, but it was only 16.7% in aposymbiotic aphids. Likewise, two nonessential amino acids, tyrosine and serine, represented 8.9% and 5.6% of total amino acids in symbiontic aphids, respectively, but they enhanced to 21.1% and 13.6% in aposymbiotic aphids. It seems likely that the elevated free amino acid concentration in aposymbiotic aphids was caused by the limited protein anabolism as the result of the unbalanced amino acid composition. [source]

    Functional response of Neoseiulus californicus (Acari: Phytoseiidae) to Tetranychus urticae (Acari: Tetranychidae) on strawberry leaves

    J. J. Ahn
    Abstract Neoseiulus californicus (McGregor) is a predatory mite employed for biological control of the agricultural pest Tetranychus urticae (Koch). We explored whether environmental differences, in this case the trichome densities of abaxial leaf surfaces of strawberry cultivars (,Maehyang' and ,Sulhyang' varieties) affect the functional response of adult female N. californicus preying on immature stages (egg, larva and nymph) of T. urticae. We also evaluated the functional response of N. californicus to eggs of T. urticae at different temperatures (15, 20, 25, 30 and 35°C). We conducted a logistic regression of the proportion of prey consumed as a function of initial prey density to identify functional response types, and used nonlinear least-squares regression and the random predator equation to estimate attack rates and handling times. The functional response of adult female N. californicus to T. urticae was not influenced by non-glandular trichomes on abaxial leaves but was affected by temperature. Overall, adult female N. californicus exhibited a type 2 functional response to T. urticae. The handling time of N. californicus was highest (1.9970 h) against T. urticae nymphs. The attack rate did not change much at 15,30°C, but was significantly higher at 35°C. The handling time decreased significantly with increasing temperature at 15,35°C. At 35°C, the attack rate was highest (0.2087) and the handling time was lowest (0.9511 h). [source]

    Effect of vegetation management on autumn dispersal of Tetranychus urticae (Acari: Tetranychidae) from tomato

    E. D. Meck
    Abstract Autumn dispersal of twospotted spider mite (Tetranychus urticae Koch) from tomato to overwintering host plants was studied in field experiments during 2004,2006. Three vegetation management strategies (herbicide, cultivation and no vegetation control) were established around mite-infested, senescing tomato plants. Tetranychus urticae dispersal was monitored using trap plants of common chickweed (Stellaria media) at 2, 6 and 12 m from the tomatoes within each vegetation management plot. Chickweed plants were sampled in the autumn and spring from 2004 to 2006. Sticky traps were placed next to trap plants in the autumn of 2005 to monitor aerial dispersal of mites. Mite populations infesting chickweed were low, and autumn dispersal of mites from tomatoes to the chickweed plots was considered to be short range. The vegetation management strategies had no effect on mite densities found in the chickweed, but the capture of mites on sticky traps indicated that aerial dispersal was also a means of dispersal to overwintering hosts. [source]

    Aphid species identification using cuticular hydrocarbons and cytochrome b gene sequences

    F. Raboudi
    Abstract:, In Tunisia, four major aphid species have been identified based on adult female's morphological characters: Aphis gossypii Glover, Aphis craccivora Koch, Myzus persicae Sluzer and Macrosiphum euphorbiae Thomas. Species identification at individual collection sites is often difficult because adults are much fewer in number than larvae which are not so easy to distinguish morphologically. We therefore set up an experiment to determine if cuticular hydrocarbon phenotypes and mitochondrial DNA haplotypes could be used to distinguish such sympatric species. Results showed that each species had an unique cuticular hydrocarbon phenotype and mitochondrial cytochrome b sequence. Cytochrome b restriction fragment-length polymorphism markers, especially DdeI, identified in this sudy constitute a relatively simple and useful approach to distinguish the four species even at the nymphal stage. [source]

    History of science , spores

    Lewis B Perry Memorial Lecture 200
    Abstract Bacterial endospores were first studied 130 years ago by Cohn in 1876 and independently by Koch in the same year. Although spore dormancy and resistance have been much studied since then, questions still remain concerning the basic mechanisms and the kinetics of heat inactivation in particular. Likewise, the extreme dormancy and longevity of spores was recognized early on and later greatly extended but still evade complete understanding. Evidence has accumulated for the involvement of specific spore components such as calcium, dipicolinic acid, small acid soluble proteins in the core and peptidoglycan in the cortex. Involvement of physical factors too, such as the relative dehydration of the core, maybe in a high-viscosity state or even in a glassy state, has added to appreciation of the multicomponent nature of dormancy and resistance. Spore-former morphology formed the basis for early classification systems of sporeformers from about 1880 and consolidated in the mid-1900s, well prior to the use of modern genetic procedures. With respect to sporulation, groundbreaking sequence studies in the 1950s provided the basis for later elucidation of the genetic control widely relevant to many cell differentiation mechanisms. With respect to the breaking of dormancy (activation and germination), the elucidation of mechanisms began in the 1940s following the observations of Hills at Porton who identified specific amino acid and riboside ,germinants', and laid the basis for the later genetic analyses, the identification of germinant receptor genes and the elucidation of key germination reactions. The nonexponential nature of germination kinetics has thwarted the development of practical Tyndallization-like processing. So inactivation by heat remains the premier method of spore control, the basis of a huge worldwide industry, and still relying on the basic kinetics of inactivation of Clostridium botulinum spores, and the reasoning regarding safety first evolved by Bigelow et al. in 1920 and Esty and Meyer in 1922. ,Newer' processes such as treatment with ionizing radiation (first proposed in 1905) and high hydrostatic pressure (first proposed in 1899) may be introduced if consumer resistance and some remaining technical barriers could be overcome. [source]

    Influence of water extracts from the surface of two Yew (Taxus) species on mites (Tetranychus urticae)

    Miroslawa Furmanowa
    Abstract Taxus cuspidata and Taxus media var. Hicksii contain paclitaxel, among other taxoids, on the surface of the needles. These compounds were removed by 5-s dipping of the needles in water just below its boiling point at 96°C and at 60°C and 40°C. Taxus cuspidata contained a fourfold higher concentration of paclitaxel than Taxus media var. Hicksii. The extract with the higher concentration of paclitaxel was more harmful to the mites Tetranychus urticae Koch, increasing their mortality 150%, prolonging development by ca. 20% and lowering the average fecundity from 112 in the control to 16.13 after treatment with Taxus cuspidata; also, the net reproductive rate dropped from 70.24 to 6.70, which is more than a tenfold reduction. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Topographic Anatomy of the Inferior Pyramidal Space: Relevance to Radiofrequency Catheter Ablation

    Inferior Pyramidal Space and Ablation.Introduction: Radiofrequency catheter ablation carried out in the vicinity of the triangle of Koch risks damaging not only the AV conduction tissues but also their arterial supply. The aim of this study was to examine the relationship of the AV nodal artery to the inferior pyramidal space, the triangle of Koch, and the right atrial endocardial surface. Methods and Results: We studied 41 heart specimens, 24 by gross dissections and 17 by histologic sections. The proximity of the AV nodal artery to the surface landmarks of the triangle of Koch was variable, but it was notable that in 75% of specimens the artery passed close to the endocardial surface of the right atrium and within 0.5 to 5 mm of the mouth of the coronary sinus. In all specimens, the mean distance of the artery to the endocardial surface was 3.5 ± 1.5 mm at the base of Koch's triangle. The location of the compact AV node and its inferior extensions varied within the landmarks of the triangle. At the mid-level of Koch's triangle, the compact node was medially situated in 82% of specimens, but it was closer to the hinge of the tricuspid valve in the remaining 18% of specimens. In 12% of specimens, the inferior parts of the node extended to the level of the mouth of the coronary sinus. Conclusion: The nodal artery runs close to the orifice of the coronary sinus, the endocardial surface of the right atrium, the middle cardiac vein, and the specialized conduction tissues in most hearts. The nodal artery and/or the AV conduction tissues can be at risk of damage when ablative procedures are carried out at the base of the triangle of Koch. [source]

    Passive immunization against oral AIDS virus transmission: An approach to prevent mother-to-infant HIV-1 transmission?

    Regina Hofmann-Lehmann
    To develop immunoprophylaxis regimens against mother-to-child human immunodeficiency virus type 1 (HIV-1) transmission, we established a simian,human immunodeficiency virus (SHIV) model in neonatal macaques that mimics intrapartum mucosal virus exposure (T.W. Baba, J. Koch, E.S. Mittler et al.: AIDS Res Hum Retroviruses 10:351,357, 1994). We protected four neonates from oral SHIV-vpu+ challenge by ante- and postpartum treatment with a synergistic triple combination of immunoglobulin (Ig) G1 human anti-HIV-1 neutralizing monoclonal antibodies (mAbs) (T.W. Baba, V. Liska, R. Hofmann-Lehmann et al.: Nature Med 6:200,206, 2000), which recognize the CD4-binding site of Env, a glycosylation-dependent gp120, or a linear gp41 epitope. Two neonates that received only postpartum mAbs were also protected from oral SHIV-vpu+ challenge, indicating that postpartum treatment alone is sufficient. Next, we evaluated a similar mAb combination against SHIV89.6P, which encodes env of primary HIV89.6. One of four mAb-treated neonates was protected from infection and two maintained normal CD4+ T-cell counts. We conclude that the epitopes recognized by the three mAbs are important determinants for achieving protection. Combination immunoprophylaxis with synergistic mAbs seems promising to prevent maternal HIV-1 transmission in humans. [source]

    Mycoplasma genitalium: the aetiological agent of urethritis and other sexually transmitted diseases

    Jřrgen Skov Jensen
    ABSTRACT Mycoplasma genitalium was first isolated in 1980 from two of 13 men with non-gonococcal urethritis (NGU). It shares several features with M. pneumoniae, a recognized respiratory tract pathogen. It is extremely difficult to isolate by culture. The development of sensitive and specific polymerase chain reaction (PCR) assays in the early 1990s made clinical studies possible and a significant number of publications have shown a strong association between M. genitalium and NGU, independent of Chlamydia trachomatis. The purpose of this review is to evaluate the currently available information on the associations between M. genitalium and urogenital tract infections in men and women and assess their fulfilment of the Henle,Koch postulates. It is concluded that there is very strong evidence that M. genitalium is a cause of NGU in men and cervicitis in women. Evidence for upper genital tract infections in women has begun to accrue, but further studies are needed. The optimal treatment of M. genitalium infections remains to be determined, but antibiotics of the macrolide group appear to be more active than tetracyclines. [source]

    Antibacterial activities of essential oils and extracts of Turkish Achillea, Satureja and Thymus species against plant pathogenic bacteria

    Recep Kotan
    Abstract BACKGROUND: The aims of this study were to examine the chemical composition of the essential oils and hexane extracts of the aerial parts of Satureja spicigera (C. Koch) Boiss., Thymus fallax Fisch. & CA Mey, Achillea biebersteinii Afan, and Achillea millefolium L. by GC and GC,MS, and to test antibacterial efficacy of essential oils and n -hexane, chloroform, acetone and methanol extracts as an antibacterial and seed disinfectant against 25 agricultural plant pathogens. RESULTS: Thymol, carvacrol, p -cymene, thymol methyl ether and ,-terpinene were the main constituents of S. spicigera and T. fallax oils and hexane extracts. The main components of the oil of Achillea millefolium were 1,8-cineole, ,-cadinol and caryophyllene oxide, whereas the hexane extract of this species contained mainly n -hexacosane, n -tricosane and n -heneicosane. The oils and hexane extracts of S. spicigera and T. fallax exhibited potent antibacterial activity over a broad spectrum against 25 phytopathogenic bacterial strains. Carvacrol and thymol, the major constituents of S. spicigera and T. fallax oils, also showed potent antibacterial effect against the bacteria tested. The oils of Achillea species showed weak antibacterial activity. Our results also revealed that the essential oil of S. spicigera, thymol and carvacrol could be used as potential disinfection agents against seed-borne bacteria. CONCLUSION: Our results demonstrate that S. spicigera, T. fallax oils, carvacrol and thymol could become potentials for controlling certain important agricultural plant pathogenic bacteria and seed disinfectant. Copyright © 2009 Society of Chemical Industry [source]

    Distribution and phenology of ixodid ticks in southern Zambia

    N. Speybroeck
    Abstract Distribution data for epidemiologically important ticks (Acari: Ixodidae) in the Southern Province of Zambia, one of the main cattle areas of the country, are presented. Boophilus microplus (Canestrini) was not recorded in southern Zambia, whereas Boophilus decoloratus (Koch) is present throughout the area. New distribution patterns for less economically important ixodid ticks are also discussed. Southern Zambia is a transition zone because it is the most northern area in Africa where mixed Rhipicephalus appendiculatus Neumann and Rhipicephalus zambeziensis Walker, Norval & Corwin populations were reported. Although a second generation of adult R. appendiculatus/R. zambeziensis was encountered, simulations indicated that this phenomenon is very rare in southern Zambia, mainly because of the colder temperatures during the early dry season and lower rainfall. These simulations were supported by a development trial under experimental conditions. Tick body size measurements showed that southern Zambian ticks are larger than eastern Zambian R. appendiculatus. It is hypothesized that body size is related to diapausing intensity in this species. The epidemiological consequences are that a different approach to control Theileria parva (Theiler) (Piroplasmida: Theileriidae) and other tick-borne diseases is needed in southern Zambia, compared to the one adopted in eastern Zambia. [source]

    Fractal-shaped microstrip dual-mode bandpass filter with asymmetrical sinuous spurlines

    Fu Tong
    Abstract In this article, miniaturized dual-mode bandpass filters using Koch fractal-shaped slots and sinuous spurlines are proposed. Because of the space-filling property of the fractal geometry, the transmission characteristics of this filter can be adjusted by the iteration order of the Koch fractal curve. Moreover, asymmetrical sinuous spurlines are adopted to tune the degenerate modes. Compared with the conventional square-patch filters, fractal slots and sinuous spurlines can also provide more current distribution distortions which improve the electrical length and realize a compact design. Experimental data in agreement with theoretical data verify the design methodology. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 745,747, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24167 [source]

    New species and additional records of Paederinae and Aleocharinae from Iran (Coleoptera, Staphylinidae)

    Volker Assing
    Abstract Four species of Staphylinidae are (re-)described and illustrated: Lathrobium impressifrons Eppelsheim, 1884, sp. propr. (previously regarded as a subspecies of L. laevipenne Heer, 1839) and L. serriae sp. n. (Iran: Razavi Khorasan province) of the Paederinae, and Pronomaea procerula sp. n. (Iran: Fars and Boyer Ahmadi va Kohkiluyeh provinces) and Tetralaucopora bicolorata sp. n. (Iran: Fars province) of the Aleocharinae. Lathrobium szekessyi Coiffait, 1972, syn. n., is placed in the synonymy of L. roubali Koch, 1944. A lectotype is designated for Lathrobium impressifrons. Additional records of Paederinae and Aleocharinae primarily from Iran are reported, among them 13 first records from Iran and one from Georgia. The distributions of 8 species are mapped. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Microsatellite diversity associated with ecological factors in Hordeum spontaneum populations in Israel

    MOLECULAR ECOLOGY, Issue 6 2001
    Timo Turpeinen
    Abstract Microsatellite diversity at 18 loci was analysed in 94 individual plants of 10 wild barley, Hordeum spontaneum (C. Koch) Thell., populations sampled from Israel across a southward transect of increasing aridity. Allelic distribution in populations was not distributed randomly. Estimates of mean gene diversity were highest in stressful arid-hot environments. Sixty-four per cent of the genetic variation was partitioned within populations and 36% between populations. Associations between ecogeographical variables and gene diversity, He, were established in nine microsatellite loci. By employing principle component analysis we reduced the number of ecogeographical variables to three principal components including water factors, temperature and geography. At three loci, stepwise multiple regression analysis explained significantly the gene diversity by a single principal component (water factors). Based on these observations it is suggested that simple sequence repeats are not necessarily biologically neutral. [source]

    Verbascum eskisehirensis sp. nov. (Scrophulariaceae) from central Anatolia, Turkey

    Faik Ahmet Karavelio, ullar
    Verbascum eskisehirensis Karavel., Ocak & Ekici sp. nov. (sect. Bothrosperma Murb.) is described and illustrated from Turkey. This new species is confined to B3 Eskisehir in central Anatolia. A morphological comparison is made with the closely related species; V. oreophilum K. Koch and V. pyramidatum M. Bieb. In addition, a cluster analysis was conducted and a distribution map of the new species and the related species is also given. [source]

    In vitro effects of flutriafol and azoxystrobin on Beauvaria bassiana and its efficacy against Tetranychus urticae

    Mutimura C Gatarayiha
    Abstract BACKGROUND: Testing the compatibility of chemical pesticides and fungal biocontrol agents is necessary if these two agents are to be applied together in the integrated management of plant pests and diseases. In this study, the fungicides azoxystrobin (a strobilurin) and flutriafol (a triazole) were tested in vitro for their effects on germination of conidia and mycelial growth of Beauveria bassiana (Bals.) Vuill. and in bioassay for their effect on fungal activity against Tetranychus urticae Koch. The fungicides were tested at three different concentrations [recommended rate for field use (1 × X) and the dilutions 10,1× X and 10,2× X]. RESULTS: Flutriafol inhibited growth of mycelia and germination of the fungal conidia at all concentrations tested in vitro, and also reduced the efficacy of B. bassiana in bioassays against mites. The inhibitive effect of azoxystrobin in vitro varied with the concentration applied. A significant effect was observed at 1 × X and 10,1× X concentrations on both the germination of conidia and mycelia growth. At 10,2× X concentration, azoxystrobin showed little effect on B. bassiana. However, when this fungicide was tested in bioassays, none of the concentrations reduced B. bassiana activity against mites. CONCLUSION: Azoxystrobin was most compatible with B. bassiana, while flutriafol was the most harmful. Further studies are required to confirm the negative effect of flutriafol on B. bassiana activity. Copyright © 2010 Society of Chemical Industry [source]

    The discovery of HNPC-A3066: a novel strobilurin acaricide

    Aiping Liu
    Abstract BACKGROUND: Although more than ten strobilurin analogues have been commercialized since 1996 as fungicides, only one was available as an acaricide as of 2003. To search for novel strobilurin analogues with unique biological activities, a synthetic screening programme was carried out. RESULTS: Syntheses of compounds analogous to the commercialized fungicide metominostrobin and the acaricide fluacrypyrim led to the discovery of a lead compound, (E)-2-{2-[[3,5-bis(trifluoromethyl)phenoxy]methyl]phenyl}-2-(methoxyimino)- N -methylacetamide (3b), that showed moderate acaricidal activity against Tetranychus urticae Koch. Compound 3b has a 3,5-(CF3)2 -phenoxymethyl group instead of the unsubstituted phenoxy substituent in metominostrobin. Optimization of compound 3b was achieved by introducing an oxime ether bridge along with an alkylthio(alkyl) branch in place of the oxymethylene chain between two aromatic moieties, as well as by replacing the methoxyiminoacetamide group with a methoxyacrylate structure, leading to (E)- methyl 2-{2-[[[(Z)[1-(3,5-bis(trifluoromethyl)phenyl)-2-methylthioethylidene]amino]oxy] methyl]phenyl}-3-methoxyacrylate (6c) and (E)- methyl 2-{2-[[[(Z)[1-(3,5-bis(trifluoromethyl)phenyl)-1-methylthiomethylidene]amino]oxy]methyl]phenyl}-3-methoxyacrylate (9a, HNPC-A3066). CONCLUSION: The above two compounds (6c, 9a) were shown to exhibit potent acaricidal and fungicidal activity. Compound 9a (HNPC-A3066) also exhibits larvicidal and ovicidal activities against various acarids. The acaricidal potency is comparable with those of commercial acaricides such as fluacrypyrim, tebufenpyrad and chlorfenapyr. Copyright © 2008 Society of Chemical Industry [source]

    Impact of intraguild predation and lambda-cyhalothrin on predation efficacy of three acarophagous predators

    Caroline Provost
    Abstract This laboratory study reports the interaction of three predators found in commercial apple orchards in Quebec, Hyaliodes vitripennis (Say) (Hemiptera: Miridae), Harmonia axyridis Pallas (Coleoptera: Coccinellidae) and Amblyseius fallacis (Garman) (Acarina: Phytoseiidae). First, intraguild predation between H vitripennis and the two other predators was characterized in the absence and presence of their extraguild prey, Tetranychus urticae Koch. The results showed an asymmetrical interaction in favour of the larger predator and the levels of intraguild predation were weak for the two predatory combinations. Presence of the phytophagous mite reduced the intensity of intraguild predation in the predatory combination of H axyridis and H vitripennis. Second, the effects of intraguild predation and the application of lambda-cyhalothrin on predation efficacy of the predators were evaluated. The application of the insecticide reduced prey consumption of H vitripennis and H axyridis but did not affect that of A fallacis. Combination of predators and an insecticide application resulted in two different situations depending on the species involved: a reduced predation efficacy for the combination of H vitripennis and H axyridis due to a knockdown effect caused by the insecticide, and no effect on T urticae consumption for H vitripennis and A fallacis. It is suggested that an integrated pest management program based on H vitripennis, A fallacis and lambda-cyhalothrin may be evaluated to repress phytophagous mites in Quebec orchards. Copyright © 2005 Society of Chemical Industry [source]

    Comparative analysis of neonicotinoid binding to insect membranes: I. A structure,activity study of the mode of [3H]imidacloprid displacement in Myzus persicae and Aphis craccivora

    Dr Hartmut Kayser
    Abstract Neonicotinoids bind selectively to insect nicotinic acetylcholine receptors with nanomolar affinity to act as potent insecticides. While the members of the neonicotinoid class have many structural features in common, it is not known whether they also share the same mode of binding to the target receptor. Previous competition studies with [3H]imidacloprid, the first commercialised neonicotinoid, indicated that thiamethoxam, representing a novel structural sub-class, may bind in a different way from that of other neonicotinoids. In the present work we analysed the mode of [3H]imidacloprid displacement by established neonicotinoids and newly synthesized analogues in the aphids Myzus persicae Sulzer and Aphis craccivora Koch. We found two classes of neonicotinoids with distinct modes of interference with [3H]imidacloprid, described as direct competitive inhibition and non-competitive inhibition, respectively. Competitive neonicotinoids were acetamiprid, nitenpyram, thiacloprid, clothianidin and nithiazine, whereas thiamethoxam and the N -methyl analogues of imidacloprid and clothianidin showed non-competitive inhibition. The chloropyridine or chlorothiazole heterocycles, the polar pharmacophore parts, such as nitroimino, cyanoimino and nitromethylene, and the cyclic or acyclic structure of the pharmacophore were not relevant for the mode of inhibition. Consensus structural features of the neonicotinoids were defined for the two mechanisms of interaction with [3H]imidacloprid binding. Furthermore, two sub-classes of non-competitive inhibitors can be discriminated on the basis of their Hill coefficients for imidacloprid displacement. We conclude from the present data that the direct competitors share the binding site with imidacloprid, whereas non-competitive compounds, like thiamethoxam, bind to a different site or in a different mode. Copyright © 2004 Society of Chemical Industry [source]

    Comparative analysis of neonicotinoid binding to insect membranes: II.

    An unusual high affinity site for [3H]thiamethoxam in Myzus persicae, Aphis craccivora
    Abstract Neonicotinoids represent a class of insect-selective ligands of nicotinic acetylcholine receptors. Imidacloprid, the first commercially used neonicotinoid insecticide, has been studied on neuronal preparations from many insects to date. Here we report first intrinsic binding data of thiamethoxam, using membranes from Myzus persicae Sulzer and Aphis craccivora Koch. In both aphids, specific binding of [3H]thiamethoxam was sensitive to temperature, while the absolute level of non-specific binding was not affected. In M persicae, binding capacity (Bmax) for [3H]thiamethoxam was ca 450 fmol mg,1 of protein at 22 °C and ca 700 fmol mg,1 of protein at 2 °C. The negative effect of increased temperature was reversible and hence not due to some destructive process. The affinity for [3H]thiamethoxam was less affected by temperature: Kd was ca 11 nM at 2 °C and ca 15 nM at 22 °C. The membranes also lost binding sites for [3H]thiamethoxam during prolonged storage at room temperature, and upon freezing and thawing. In A craccivora, [3H]thiamethoxam was bound with a capacity of ca 1000 fmol mg,1 protein and an affinity of ca 90 nM, as measured at 2 °C. Overall, the in vitro temperature sensitivity of [3H]thiamethoxam binding was in obvious contrast to the behaviour of [3H]imidacloprid studied in parallel. Moreover, the binding of [3H]thiamethoxam was inhibited by imidacloprid in a non-competitive mode, as shown with M persicae. In our view, these differences demonstrate that thiamethoxam and imidacloprid, which represent different structural sub-classes of neonicotinoids, do not share the same binding site or mode. This holds also for other neonicotinoids, as we report in a companion article. Copyright © 2004 Society of Chemical Industry [source]

    Can ant-eating Zodarion spiders (Araneae: Zodariidae) develop on a diet optimal for euryphagous arthropod predators?

    Abstract Little attention is paid to the behavioural and physiological adaptations of ant-eating predators. It is expected that there should be a strong selection for traits related to prey handling, leading to the evolution of morphological, behavioural and nutritional adaptations. Such adaptations may then entail trade-offs in handling and utilization of alternative prey. To investigate behavioural as well as nutritional adaptations and the occurrence of the corresponding trade-offs in two ant-eating spiders of the genus Zodarion [Zodarion atlanticum Pekár & Cardoso and Zodarion germanicum (C. L. Koch)], spiders are reared on two diets: ants (i.e. their preferred prey) and fruit flies (i.e. an alternative prey that is nutritionally optimal for euryphagous spiders). Food consumption is observed and several fitness-related life-history parameters are measured. Although spiders readily accept ants, more than one-third of 35 spiders refuse to consume fruit flies and starve. Furthermore, severe hunger does not induce these individuals to accept fruit flies. Starving spiders die before moulting to the second stadium. Spiders that eat fruit flies increase only little and slowly in weight, and all of these die during the first two stadia. By contrast, spiders on an ant diet increase dramatically in weight, and develop up to the fourth stadium. These data indicate that fruit flies are not suitable for Zodarion, supporting the hypothesis that there are behavioural and nutritional trade-offs. Taking into account the results of previous studies, it is suggested that nutritional trade-offs are generally important for stenophagous spiders. [source]

    Antioxidant activities of some Lamiaceae plant extracts

    Nurgun Erdemoglu
    Abstract The antioxidant activities of four Lamiaceae plants, Salvia viridis L., Salvia multicaulis Vahl, Stachys byzantina C. Koch and Eremostachys laciniata (L.) Bunge have been determined by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) as well as by flow injection analysis-luminol chemiluminescence (FIA-CL). All extracts were shown to possess a significant scavenger activity against DPPH free radical and an inhibitory effect on H2O2 - or HOCl-luminol chemiluminescence. The extracts scavenged 50% of DPPH radical ranging in the following descending order: Salvia viridis > Stachys byzantina > Salvia multicaulis > Eremostachys laciniata. The most potent extract on H2O2 -induced peak chemiluminescence was that of Salvia viridis and on HOCl-induced peak chemiluminescence was that of Stachys byzantina. The results concluded that the extracts have a potential source of antioxidants of natural origin. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Hellenistisches Christentum: Schriftverständnis,Ekklesiologie,Geschichte , By Dietrich-Alex Koch

    Thomas E. Phillips
    No abstract is available for this article. [source]

    Relative toxicity of nC24 agricultural mineral oil to Tetranychus urticae Koch (Acari: Tetranychidae) and Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) and its possible relationship to egg ultrastructure

    Yingen Xue
    Abstract The relative toxicity (LC50 values based on µg oil/cm2) is evaluated of aqueous nC24 agricultural mineral oil (AMO) emulsions to the egg, six-legged nymph (larva), eight-legged protonymph and adult stages of two-spotted mite (Tetranychus urticae) and its predator, Phytoseiulus persimilis, on French bean leaf discs, using a Potter spray tower to apply of the oil. The egg of P. persimilis was the least susceptible stage (LC50 444.84) and its LC50 was significantly higher than all other stages tested of either P. persimilis or T. urticae. The LC50 for adult female T. urticae (LC50 63.89) was significantly lower than the larva (LC50 93.86); however, there was no significant difference in response between the protonymph (LC50 70.44) and the larva, which were both higher than T. urticae eggs (LC50 17.55). LC50s for P. persimilis larva (LC50 43.87), protonymph (LC50 41.55) and adult female (LC50 53.34) were similar. Scanning electron microscopy showed that the egg surface of T. urticae is usually well covered with fine silk that may trap more oil and increase AMO efficacy. Other possible differences in AMO efficacy between T. urticae and P. persimilis may be due to differences in egg size, egg incubation period, egg surface structure and the presence of vulnerable respiratory cones in T. urticae eggs. Dose of 0.2,0.3% (w/w) is considered to be the most appropriate for nC24 AMOs use against T. urticae in combination with P. persimilis in integrated pest management programs. [source]