Publications (15)21.66 Total impact
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Article: Serological marking of Pnigalio agraules (Hymenoptera: Eulophidae) for field dispersal studies
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ABSTRACT: The parasitoid wasp Pnigalio agraules (Wlk.) is a key natural enemy of the horsechestnut leafminer Cameraria ohridella Deschka and Dimić (Lepidoptera: Gracillariidae). As a basis for mark-release-recapture studies, aimed at investigating the dispersal of this parasitoid in the field, adults of P. agraules were marked using a vertebrate-specific immunoglobulin (IgG). The marker was later detected by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The IgG was either applied externally by spraying or internally by feeding an IgG-enriched diet. Different concentrations of the marker were used and the influence of abiotic (climatic conditions, time elapsed between marking and marker examination) and biotic factors (sex and age of the parasitoids) on the detection of the immunomarker was tested. External marking by spraying led to more homogeneous labelling than feeding the marker. Parasitoids labelled with 0.25mg rabbit IgG per ten individuals contained enough immunomarker to be easily distinguished from unmarked ones. Neither the climatic conditions nor the sex or age of the insects had an influence on the detection of the marker. The IgG remained well detectable during the entire lifespan of the parasitoids, which was not negatively affected by the marking procedure. Serological marking can be used to investigate the dispersal behaviour of beneficial insects within mark-release-recapture studies.Journal of Pest Science 04/2012; 82(1):47-53. · 1.51 Impact Factor -
Article: Susceptibility of different plant species and tomato cultivars to two isolates of Pepino mosaic virus
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ABSTRACT: As Pepino mosaic virus has become a pathogen of major importance in worldwide tomato production, information is needed on possible differences between the sensitivity of cultivars towards infection. Furthermore, it is important what hosts other than Solanaceae may be virus reservoirs and are, therefore, threats for tomato cultivation. Two PepMV isolates (PepMV-Sav, E397, a European tomato isolate and PV-0554, a Peruvian pepino isolate) differing in their origin and virulence were used for several experiments to investigate these issues. The response to mechanical inoculation with PepMV was studied using 25 tomato cultivars, seven indicator plant species, and nine other possible horticultural host plants. Symptom development after infection with PepMV was monitored and the virus was detected by DAS-ELISA and IC-RT-PCR. Garlic and broad bean were shown to be additional hosts of PepMV depending on the virus isolate. Nicotiana benthamiana seems to be the most sensitive indicator among all tested indicator plants developing symptoms. Both PepMV isolates infected all tested tomato cultivars. Development of disease symptoms depended on the cultivar and the virus isolate but symptoms were not visible in all cases. None of the cultivars showed tolerance against the two isolates but two responded with a lower susceptibility at an absorbance level of 0.2 (healthy control 0.09). It was observed that some cultivars grown hydroponically showed also lower losses in biomass and yield. Data indicated a correlation between absorbance level in DAS-ELISA and reduction in total tomato growth. KeywordsDAS-ELISA–IC-RT-PCR–Indicator plants–PepMV–Potexvirus–Solanaceae–SymptomsEuropean Journal of Plant Pathology 04/2012; 129(4):579-590. · 1.41 Impact Factor -
Article: A model system for plant-virus interaction—infectivity and seed transmission of Cherry leaf roll virus (CLRV) in Arabidopsis thaliana
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ABSTRACT: The wide natural incidence of Cherry leaf roll virus (CLRV) in deciduous forest trees and nurseries in northern Europe is believed to have occurred, apart from occasional mechanical spread and transmission through grafting, mainly by seed transmission. The mode of the vertical transmission and its role in the epidemiology of the virus has not been investigated, basically due to the inconvenient host-pathogen combinations studied to date. With the aim of obtaining an appropriate system for identification of viral genes and products participating in infection processes and seed transmission of CLRV, we performed infection and seed transmissibility tests with CLRV in Arabidopsis thaliana plants. Two phylogenetically and serologically different CLRV isolates were tested. Both of them were found able to infect A. thaliana plants, exhibited clear symptoms of the infection and spread systemically in the plants. Infection of the seeds and of a remarkable number of seedlings generated from infected seeds was possible for two consecutive generations. These results, for first time, report seed transmission of CLRV in the model plant A. thaliana and allow the assumption to be made of embryo invasion during seed transmission. Furthermore, first indications are given that genetically diverse CLRV isolates exhibit different abilities for vertical transmission in A. thaliana. The CLRV-A. thaliana model system is suitable for investigating viral invasion of developing plant organs and meristematic tissue, a prerequisite for successful virus dissemination via vertical transmission through seed.European Journal of Plant Pathology 04/2012; 124(3):527-532. · 1.41 Impact Factor -
Article: Complete nucleotide sequence of Cherry leaf roll virus (CLRV), a subgroup C nepovirus.
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ABSTRACT: The complete nucleotide sequence of both genomic (+)ss RNAs of a rhubarb isolate of Cherry leaf roll virus (CLRV) was determined. The larger RNA1 is 7918 nucleotides and the shorter RNA2 6360 nucleotides in size, each genome component comprising a single open reading frame (ORF). The RNA1-encoded polyprotein (P1) is 2112 amino acids long (235.6 kDa) containing domains characteristic for a proteinase-cofactor (PCo), nucleotide-binding helicase (Hel), genome-linked protein (VPg), proteinase (Pro), and an RNA-dependent RNA polymerase (Pol). The RNA2-encoded polyprotein (P2) has a molecular mass of 174.9 kDa (1589 aa) encoding the putative movement protein (MP) and the coat protein (CP) of CLRV. The genome region upstream of the MP has a coding capacity of 77 kDa, however processing of P2 by the putative virus-encoded proteinase and protein-function encoded by this region is unknown. Furthermore, it could be demonstrated that the 5'-termini including the N-terminal region (208 aa) of P1 and P2 of the rhubarb isolate of CLRV are nearly identical among the two genome segments. The taxonomic position of CLRV as member of the genus Nepovirus was confirmed by phylogenetic analyses employing the amino acid sequences of the conserved Pro-Pol region of RNA1, the complete P2, and the CP. However, clustering of Nepovirus-species according to allocated subgroups was inconsistent and depended on the compared genome fragment.Virus Research 02/2012; 163(2):678-83. · 2.94 Impact Factor -
Article: Male Phyllotreta striolata (F.) produce an aggregation pheromone: identification of male-specific compounds and interaction with host plant volatiles.
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ABSTRACT: The chrysomelid beetle Phyllotreta striolata is an important pest of Brassicaceae in Southeast Asia and North America. Here, we identified the aggregation pheromone of a population of P. striolata from Taiwan, and host plant volatiles that interact with the pheromone. Volatiles emitted by feeding male P. striolata attracted males and females in the field. Headspace volatile analyses revealed that six sesquiterpenes were emitted specifically by feeding males. Only one of these, however, elicited an electrophysiological response from antennae of both sexes. A number of host plant volatiles, e.g., 1-hexanol, (Z)-3-hexen-1-ol, and the glucosinolate hydrolysis products allyl isothiocyanate (AITC), 3-butenyl isothiocyanate, and 4-pentenyl isothiocyanate also elicited clear responses from the antenna. The active male-specific compound was identified as (+)-(6R,7S)-himachala-9,11-diene by chiral stationary phase gas-chromatography with coupled mass spectrometry, and by comparison with reference samples from Abies nordmanniana, which is known to produce the corresponding enantiomer. The pheromone compound was synthesized starting from (-)-α-himachalene isolated from Cedrus atlantica. Under field conditions, the activity of the synthetic pheromone required concomitant presence of the host plant volatile allyl isothiocyanate. However, both synthetic (+)-(6R,7S)-himachala-9,11-diene alone and in combination with AITC were attractive in a two-choice laboratory assay devoid of other natural olfactory stimuli. We hypothesize that P. striolata adults respond to the pheromone only if specific host volatiles are present. In the same laboratory set up, more beetles were attracted by feeding males than by the synthetic stimuli. Thus, further research will be necessary to reveal the components of a more complex blend of host or male-produced semiochemicals that might enhance trap attractiveness in the field.Journal of Chemical Ecology 01/2011; 37(1):85-97. · 2.66 Impact Factor -
Article: Nanoparticle-virus complex shows enhanced immunological effect against baculovirus.
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ABSTRACT: Insects protect themselves from majority of infections by a non-specific innate immune system (present in both vertebrates and invertebrates). Bombyx mori nuclear polyhedrosis virus (BmNPV), a baculovirus, causing the deadly grasserie disease is a scourge to silkworm industry and we report here the first success in combating this disease with the help of a nanosilica-virus complex. Hydrophobic aluminium silicate nanoparticles were mixed with live BmNPV in vitro. This mixture was injected into one day old 5th instar silkworm larvae (into the hemocoel at the third abdominal spiracle) before challenging the larvae with live BmNPV via a second injection. This led to substantial enhancement of longevity in the diseased silkworm larvae and 35 +/- 5.3% larvae completed their lifecycle (i.e., formed normal pupae and enclosed as moth). On the other hand, 100% larvae infected with BmNPV alone died within 36 hours. The larvae treated with nanoparticles before infection had a longer lifespan but all of them eventually succumbed, not a single larva metamorphosed to adult stage. Results suggest two pathways of host protective response--one mediated by nanoparticlealone and the second, more important, via non-specific innate immunological mechanism. AFM and confocal studies show that nanoparticles alter 3-D molecular structure of the virus envelope. Possibly this exhibits novel potent epitope(s) which stimulate(s) anti-viral machinery in infected silkworm larvae. SDS-PAGE results suggest that 39 KDa viral protein is the major target of the nanoparticles.Journal of Nanoscience and Nanotechnology 09/2009; 9(9):5567-71. · 1.56 Impact Factor -
Article: Impact of Piriformospora indica on tomato growth and on interaction with fungal and viral pathogens.
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ABSTRACT: Piriformospora indica is a root endophytic fungus with plant-promoting properties in numerous plant species and induces resistance against root and shoot pathogens in barley, wheat, and Arabidopsis. A study over several years showed that the endophyte P. indica colonised the roots of the most consumed vegetable crop tomato. P. indica improved the growth of tomato resulting in increased biomass of leaves by up to 20%. Limitation of disease severity caused by Verticillium dahliae by more than 30% was observed on tomato plants colonised by the endophyte. Further experiments were carried out in hydroponic cultures which are commonly used for the indoor production of tomatoes in central Europe. After adaptation of inoculation techniques (inoculum density, plant stage), it was shown that P. indica influences the concentration of Pepino mosaic virus in tomato shoots. The outcome of the interaction seems to be affected by light intensity. Most importantly, the endophyte increases tomato fruit biomass in hydroponic culture concerning fresh weight (up to 100%) and dry matter content (up to 20%). Hence, P. indica represents a suitable growth promoting endophyte for tomato which can be applied in production systems of this important vegetable plant not only in soil, but also in hydroponic cultures.Mycorrhiza 09/2009; 20(3):191-200. · 2.63 Impact Factor -
Article: Differentiation of Cherry leaf roll virus isolates from various host plants by immunocapture-reverse transcription-polymerase chain reaction-restriction fragment length polymorphism according to phylogenetic relations.
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ABSTRACT: A restriction fragment length polymorphism assay (RFLP) was developed to differentiate Cherry leaf roll virus (CLRV) isolates according to phylogenetic clades by examining restriction patterns from partial 3' non-coding region (NCR) genomic fragments (approx. 420bp). The 3' NCR fragment from 43 CLRV isolates belonging to different phylogenetic groups were compared after restriction analysis with the endonucleases Bsp143I, AluI, RsaI, EcoRI and Eco130I, and another 23 isolates were analyzed by computer assisted restriction analysis. The restriction endonucleases Bsp143I, AluI and RsaI enabled the differentiation of isolates from group B and all but two isolates belonging to group A. A major proportion of group E isolates could also be discriminated. The remainder of the group E isolates were indistinguishable from isolates belonging to phylogenetic group C or D2. Isolates belonging to group D1 could not be differentiated from two group A isolates. The method was applied successfully in an IC-RT-PCR-RFLP assay to differentiate samples from walnut, black elderberry and birch and determine their phylogenetic relationships. In future, this method will facilitate rapid phylogenetic classification of CLRV isolates detected in certain host plants by the universal immunocapture-reverse transcription-polymerase chain reaction (IC-RT-PCR), and will be suitable for studying CLRV population diversity as well as genetic drift within virus populations.Journal of virological methods 02/2009; 157(2):147-54. · 2.13 Impact Factor -
Article: Persistence of the entomopathogenic fungus Lecanicillium muscarium Zare & Gams under ambient conditions in the field.
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ABSTRACT: Positive results of laboratory trials, which proofed the effectiveness of the entomopathogenic fungus L. muscarium against endophytic larvae of the horse chestnut leafminer moth Cameraria ohridella DESCHKA et DIMIC, led to outdoor trials. One aspect of these trials was to determine the persistence of the fungus, which was used as commercial product Mycotal (Koppert, NL) and as strain V24 from the section Phytomedicine. In different variants several spore concentrations and the influence of an oil-containing adjuvant (Koppert, NL) were tested. The persistence of the fungus was determined through the number of colony forming units (cfu) after impressing the leaves on agar plates. The fungus could be detected until 14 days past application (dpa), with differences between the variants, despite most unfavourable weather conditions, like above-average of temperature and hours with sunshine as well as low humidity and heavy rainfall. In all variants were found dead and moulding larvae within the mines.Communications in agricultural and applied biological sciences 01/2009; 74(2):353-6. -
Article: Soil application of Beauveria bassiana to control Ceratitis capitata in semi field conditions.
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ABSTRACT: The Mediterranean fruit fly Ceratitis capitata (Wiedemann) is a highly polyphagous pest of economic importance cultures in Syria, as in many other parts of the world. The potential of the entomopathogenic fungus Beauveria bassiona BALS (VUIL.) strain 412 against adults of Mediterranean fruit fly C. capitata was evaluated in semi field conditions during the summer. Soil (5-7 cm high) was filled into plastic container (27 cm x 32 cm). In one container 75 pupae, two days before emergency, were spread uniformly on the soil. Then the pupae were covered with soil (4-5 cm layer). After that, 30 ml suspension of fungal spores (4 x 10(8) spores/ml) was applied to the soil surface using a dash bottle. This corresponded to a spore density of 1.3 x 10(7) spores/cm2 on soil. Water and food (1:4 yeast, sucrose) were placed in the cages for the emerged flies. The semi-field evaluation of B. bassiana revealed a fly mortality of about 46% compared to 16% in the control. In addition 72% of dead flies were moulded in the treatment. These results indicated that the entomopathogenic fungus B. bassiana was pathogen against the adults of C. capitata not only in the laboratory condition but also under field condition. That means B. bassiana could decrease the offspring of C. capitata. Therefore B. bassiana could be an effective factor to control C. capitata in combination with other control methods, used in IPM program in the field.Communications in agricultural and applied biological sciences 01/2009; 74(2):357-61. -
Article: Behavioural response of Phytoseiulus persimilisin inert materials for technical application.
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ABSTRACT: A large scale application of the predatory mite Phytoseiulus persimilis Athias-Henriot for use in the biological control of spider mites in the field requires testing the behaviour of Phytoseiulus persimilis in inert materials, like millet pelts and Vermiculite (1-3 mm). In laboratory studies, the distribution of the individuals in such materials, the time of remaining in the material were proved. To examine the abiotic influences on the time of remaining in the material, the dampness of the materials was varied (0%, 5% and 10%). Moreover, the influence of attitude of materials was tested. The time of emigration from the material was noted for each individual. Emigration from all dry materials was completed 15 minutes at the latest after set up of the mites. The increase of dampness had an obvious effect on the time of remaining in the material. In this respect the material millet pelts showed the most favourable effect with 10% dampness. Increasing attitude of material the mobility of predatory mites will be influenced negatively above 75 cm. Up to 50 cm, mites have not a problem to move in the material and the time of remaining can be prolonged considerably.Communications in agricultural and applied biological sciences 01/2009; 74(2):397-400. -
Article: Effect of the entomopathogenic fungus Lecanicillium muscariumon the predatory mite Phytoseiulus persimilis as a non-target organism.
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ABSTRACT: In biological control, different benefit organisms have to combine for an effective management. If entomopathogenic fungi will be integrated, than it has to be considered also the effect on non-target organisms Like beneficial arthropods. Because of the high importance of predatory mite Phytoseiulus persimilis in biological control it was to determine side effects of Leconicillium muscarium on this species. In two standardised biotests in petri dish and on plants (P. vulgaris) individuals were dipped in suspension or set down on leafs after spraying with L. muscarium at different spore density. Results indicate pathogenicity for the predatory mite in principle. But the dimension of infection risk decrease, all the more conditions approach to practical sequence. Under practical conditions on plants and in practical relevant concentration of 10(6) and 10(7) sp./ml no risk is to expect on the plant.Communications in agricultural and applied biological sciences 02/2008; 73(3):395-403. -
Article: Susceptibility of Ceratitis capitata Wiedemann (Diptera: Tephritidae) to entomopathogenic fungi.
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ABSTRACT: The Mediterranean fruit fly Ceratitis capitata (Wiedemann) is one of the most serious pest of fruits in Syria and present all year round. This fly is active on different host plants, such as mango, peach, fig, apple, pear, and citrus. The number of generations per year varies with local temperatures and host plant. The objective of this research was: to evaluate the pathogenicity of entomopathogenic fungi on adults of C. capitata under laboratory conditions. Flies for experiments were obtained from a population reared in Laboratory conditions at 25 +/- 2 degrees C, 70 +/- 2% RH, and a photoperiod of 16:8 [L: D] h. Four concentrations (3 x 10(4), 3 x 10(5), 3 x 10(6), 3 x 10(7) conidia/ml) of Beauveria bassiano (Balsamo) and Paecilomyces fumosoroseus (Wize) were tested on adults of C. capitata less than 3 days old. The flies were inoculated with spores by dipping them for 10-15 seconds in 10 ml of conidial suspension or water for control respectively. After that, flies were transferred to plastic cages with diet and water. There were 10 flies per cage and 4 replicates per concentration. Adults of the Mediterranean fruit fly, C. copitata, were high susceptible. In case of B. bassiana 100% of flies were dead at 3 x 10(7) conidia/ml and 82.5% at 3 x 10(6) conidia/ml. For P. fumosoroseus the mortality of flies was 70% at 3 x 10(7) conidia/ml and 62.5% at 3 x 10(7) conidia/ml. However, in low levels of concentration (3 x 10(4) and 3 x 10(5) conidia/ml respectively) only 7.5% and 30% flies died. Mouldiness of the dead flies ranged from 77.5% to 72.5% for the two higher concentrations (3 x 10(7) and 3 x 10(6) conidia/mt) of B. bassiona and 52.5% for P. fumosoroseus at 3 x l0(7) conidia/ml. The fungal mycelium of both entomopathogenic fungi emerged through the soft parts of the exoskeleton, such as the wing bases, legs bases, head and membranous regions of the abdomen. In case of B. bassiana additional the ovipositor was mouldy.Communications in agricultural and applied biological sciences 02/2008; 73(3):589-96. -
Article: Pathogenicity of entomopathogenic fungi on hibernating pupae of Cameraria ohridella Deschka & Dimic 1986 (Lepidoptera, Gracillariidae). Part 2: Efficacy of entomopathogenic fungi against pupa in her pupal cell.
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ABSTRACT: The naked pupae of chestnut leafminer Cameraria ohridella are susceptible for entomopathogenic fungi Paecilomyces fumosoroseus strain P6; Lecanicillium muscarium strain V24; Metarhizium anisopliae strain M72 and Beauveria bassiana strain B412. Their activity at low temperature is advantageous especially for the use in the winter season. (Richter et al., 2007a). Therefore the possibility of infection should be examined in biotest for pupae in their pupal cells on leaf of chestnut at conditions Like in winter. Efficacy of entomopathogenic fungi is decreased, if pupae are in their pupal cells. But fungi, especially L. muscarium, proved the ability to infect pupae of C. ohridella in their pupal cells. Infected pupae moulded in their pupal cells after application. Infection doesn't come from spores. In semi field trials with L. muscarium 60% of pupae were infected in their pupal cells and died after incubation with mouldiness.Communications in agricultural and applied biological sciences 02/2007; 72(3):411-21. -
Article: Host species-dependent population structure of a pollen-borne plant virus, Cherry leaf roll virus.
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ABSTRACT: Cherry leaf roll virus (CLRV) belongs to the Nepovirus genus within the family Comoviridae. It has a host range which includes a number of wild tree and shrub species. The serological and molecular diversity of CLRV was assessed using a collection of isolates and samples recovered from woody and herbaceous host plants from different geographical origins. Molecular diversity was assessed by sequencing a short (375-bp) region of the 3' noncoding region (NCR) of the genomic RNAs while serological diversity was assessed using a panel of seven monoclonal antibodies raised initially against a walnut isolate of CLRV. The genomic region analyzed was shown to exhibit a significant degree of molecular variability with an average pairwise divergence of 8.5% (nucleotide identity). Similarly, serological variability proved to be high, with no single monoclonal antibody being able to recognize all isolates analyzed. Serological and molecular phylogenetic reconstructions showed a strong correlation. Remarkably, the diversity of CLRV populations is to a large extent defined by the host plant from which the viral samples are originally obtained. There are relatively few reports of plant viruses for which the genetic diversity is structured by the host plant. In the case of CLRV, we hypothesize that this situation may reflect the exclusive mode of transmission in natural plant populations by pollen and by seeds. These modes of transmission are likely to impose barriers to host change by the virus, leading to rapid biological and genetic separation of CLRV variants coevolving with different plant host species.Journal of Virology 04/2006; 80(5):2453-62. · 5.40 Impact Factor
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Institutions
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2012
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Österreichische Agentur für Gesundheit und Ernährungssicherheit
Vienna, Vienna, Austria
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2007–2012
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Humboldt-Universität zu Berlin
- Department of Crop and Animal Sciences
Berlin, Land Berlin, Germany
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