Nuova ricerca

Pasqualina GRAZIOSO

Personale tecnico amministrativo
Dipartimento di Scienze della Vita sede ex-Biologia
Referente informatico
Dipartimento di Scienze della Vita sede ex-Biologia

Home | Curriculum(pdf) | Didattica |


Pubblicazioni

2016 - Long Chain Alcohols Produced by Trichoderma citrinoviride Have Phagodeterrent Activity Against the Bird Cherry-Oat Aphid Rhopalosiphum padi [Articolo su rivista]
Ganassi, Sonia; Grazioso, Pasqualina; Sabatini, Maria Agnese
abstract

In this study we report the effects of fungal metabolites isolated from cultures of the fungus Trichoderma citrinoviride ITEM 4484 on the feeding preference of the aphid Rhopalosiphum padi, a major pest of cereal crops. Different phagodeterrent metabolites were purified by a combination of direct and reverse phase column chromatography and thin-layer chromatography. Chemical investigations, by spectroscopic and chemical methods, led to the identification of different long chain primary alcohols (LCOHs) of the general formula R-OH, wherein R is a long, unbranched, unsubstituted, linear aliphatic group. LCOHs have been reported as components of lepidopteran pheromone blends, but their phagodeterrent effect to aphids is herein reported for the first time. We studied the effects of LCOHs on R. padi by behavioral and electrophysiological bioassays. Feeding preference tests that were carried out with winged and wingless morphs of R. padi showed that LCOHs have a distinctly high phagodeterrent activity and significantly restrain aphids from settling on treated leaves already at a concentration as low as 0.15 mM (0.036 g/l). The results of different electrophysiological analyses indicate that taste receptor neurons located on the aphid tarsomeres are involved in the LCOHs perception. Behavioral assays carried out with some commercial agrochemicals, including azadirachtin A, pyrethrum and mineral oil based products, in combination with 1-hexadecanol, the LCOH most abundantly produced by T. citrinoviride ITEM 4484, showed that these different active principles can be applied together, resulting in a significant additive phagodeterrent effect. Therefore these compounds can be profitably utilized for novel applications in biotechnical control of aphid pests. The LCOHs tested have no chiral centers and therefore can be obtained in good yields and at low cost through chemical synthesis, beside than from natural sources.

2014 - Long chain alcohols, produced by the fungus Trichoderma citrinoviride as fagodeterrents for aphids control. [Abstract in Rivista]
Ganassi, Sonia; Grazioso, Pasqualina; Andolfi, A.; Altomare, C.; Sabatini, Maria Agnese; Cristofaro, A. De; Evidente, A.
abstract

Aphids are insect pests of great economic impact on agricultural production causing yield losses and reduction of quality products. They damage host plants in different ways, indeed during the feeding phase they subtract sap and spread virus diseases. Chemoreception in aphids plays a fundamental role in host plant selection and in host acceptance, therefore the identification of new compounds that interfere with these processes are of great interest for the development of innovative biotechnical control strategies. In this context, our studies aim to identify fungal metabolites that interfere with aphid feeding behavior and to understand the aphid sensory structures involved in their perception. Our previous studies led to the characterization of three distinct groups of structurally related metabolites, produced by an isolate of the fungus Trichoderma citrinoviride, which exhibit fagodeterrent activity towards different species of aphids. The first two are novel metabolites, characterized as a symmetrical disubstituted hexa-1,3-dienyl ester of acetic acid and a tetrasubstituted cyclohexane-1,3-diol, respectively and named citrantifidiene and citrantifidiol (Evidente et al., 2008). Other two compounds belong to the chemical family of bisorbicillinoids, namely bislongiquinolide and dihydrotrichodimerol (Evidente et al., 2009). Further investigations led to the isolation of a fourth group of compounds. They were identified by spectroscopic, chemical and chromatographic methods as primary alcohols: hexadecanol, octadecanol, cis-9-octadecanol and trans-9-octadecanol. Feeding preferences tests showed that these long chain alcohols have a highly significant fagodeterrent activity towards aphids of the species Rhopalosiphum padi (L.), one of the major pests of cereal crops. Antennal responses, obtained by using a standard electroantennographic technique, showed that these long chain alcohols were not able to stimulate significantly the olfactory sensilla of R. padi. Results of single chemosensory cell recordings carried out with long-chain alcohols indicate that the structures involved in their perception, particularly cis-9-octadecanol and trans-9-octadecanol, are taste cells located on the aphid tarsomeres. The tested alcohols, obtained by T. citrinoviride can modify the aphid feeding activity, thus functioning as signalling molecules that can be potentially utilized for novel applications in biotechnical control of aphid.

2011 - Survival of freezing by hydrated tardigrades inhabiting terrestrial and freshwater habitats [Articolo su rivista]
Guidetti, Roberto; Altiero, Tiziana; Bertolani, Roberto; Grazioso, Pasqualina; Rebecchi, Lorena
abstract

The seasonality and unpredictability of environmental conditions at high altitudes and latitudes govern the life cycle patterns of organisms giving rise to stresses that cause dead or development of specific adaptations. Ice formation is a major variable affecting survival of both freshwater fauna and fauna inhabiting lichens, mosses and leaf litter. Tardigrades occupy a wide range of niches in marine, freshwater and terrestrial environments. The highest number of species is found in terrestrial habitats thanks to their ability to enter anhydrobiosis and cryobiosis. The cryobiotic ability of tardigrade species from polar regions is well known. Consequently, we focused our research on the ability to survive freezing in active hydrated state using seven tardigrade species differing in phylogenetic position and collected at various altitudes and from different habitats in a temperate area. Replicates were cooled at different cooling rates (from 0.31 °C min-1 to 3.26 °C min-1). Even though the final survival and the time required by animals to recover active life were both inversely related to the cooling rates, highly significant interspecific differences were found. Species survival ability ranges from excellent to none. Species living in xeric habitats withstand freezing better than those living in hygrophilous habitats, while true limnic species do not exhibit cryobiotic capabilities. The ability to withstand freezing seems linked to the anhydrobiotic ability. The difference in cryptobiotic performance among tardigrade species seems more influenced by selective pressures linked to local adaptation to habitat characteristics than by phylogenetic relationships.

2010 - Effects of the fungus Lecanicillium lecanii on survival and reproduction of the aphid Schizaphis graminum. [Articolo su rivista]
Ganassi, Sonia; Grazioso, Pasqualina; A., Moretti; Sabatini, Maria Agnese
abstract

This study investigated the effects of a strain of the fungus Lecanicillium lecanii (Zimm.) Zare and Gams (Hypocreales: Ascomycota) on the aphid Schizaphis graminum (Rondani)(Hemiptera: Aphididae). The fungus was administered to fourth instar nymphs and to alate and apterous adult morphs as a ground rice-kernel formulation. This study showed that L. lecanii formulation affected the survival of the aphids and interacted differently with the studied morphs, the Lethal Time values being lower for alate compared to apterous morphs and nymphs. The treatment also caused a significant reduction in the fecundity of the three treated aphid groups. Histological analysis revealed that the hyphae invaded the host hemocoel of a limited number of alate and apterous morphs: the fungus only entered through the spiracles. Scanning Electron Microscope observations revealed that L. lecanii adhered to the body surface of both adults and nymphs without differentiation. In conclusion, the present study suggests that this strain might be a good candidate for a programme of biological control of S. graminum and other aphid species.

2009 - L’esperienza delle Guide scientifiche alla mostra “Darwin: Modena e 200 anni di evoluzione” [Capitolo/Saggio]
Buldrini, Fabrizio; Barbieri, Giovanna; Grazioso, Pasqualina; Tepedino, Ciro; Viotti, Giulia
abstract

2007 - Detection of fungal metabolites of various Trichoderma species by the aphid Schizaphis graminum [Articolo su rivista]
Ganassi, Sonia; A., De Cristofaro; Grazioso, Pasqualina; C., Altomare; A., Logrieco; Sabatini, Maria Agnese
abstract

The feeding preferences of alate and apterous morphs of the aphid Schizaphis graminum (Rondani) (Homoptera: Aphididae) were evaluated using leaves treated with powdered rice cultures of four fungal isolates belonging to different species of the genus Trichoderma (Deuteromycotina: Hyphomycetes). All of the fungal isolates restrained alate morphs of S. graminum from visiting treated leaves, but only Trichoderma citrinoviride Bisset also influenced the preference of apterous morphs. Trials carried out with supernatants obtained by centrifuging aqueous suspensions of the fungal cultures showed that the feeding preference of aphids was maintained in the absence of fungal spores and mycelia, supporting the hypothesis that at least part of the fungal metabolites responsible for this effect were water-soluble compounds. Electrophysiological studies showed that the structures involved in the perception of the fungal metabolites are located on the aphid tarsomeres.

2007 - Laboratory studies to assess the effects of the fungus Lecanicillium lecanii on the aphid Schizaphis graminum. [Articolo su rivista]
Ganassi, Sonia; Grazioso, Pasqualina; Logrieco, A; Moretti, A; Sabatini, Maria Agnese
abstract

The pathogenic effects of Lecanicillium lecanii ITEM 3757 towards winged and wingless adult morphs of the species Schizaphis graminum were investigated under laboratory conditions. Fungus was applied to aphids in the form of ground dried cultures grown in solid state fermentation on rice kernels. This formulation affected aphid survival and reproduction, and it interacted differently with winged and wingless aphid morphs. Scanning Electron Microscope observations pointed out a higher amount of adhering formulation and faster rates of fungal germination and sporulation on the winged cuticle. Our results suggest that the strain might be a good candidate for a programme of biocontrol against S. graminum and other aphids species.

2005 - Laboratory bioassay to assess the effects of the fungus Lecanicillium lecanii (Zimm.) Gams and Zare on the aphid Schizaphis graminum (Rondani) [Abstract in Atti di Convegno]
Ganassi, Sonia; Grazioso, Pasqualina; A., Logrieco; A., Moretti; Sabatini, Maria Agnese
abstract

The interactions between the entomopathogenic fungus Lecanicillium lecanii ITEM 3757 (syn. Verticillium lecanii), isolated from aphids, and winged and wingless adult morphs of the species Schizaphis graminum were investigated under laboratory conditions. The fungus was applied in the form of finely ground dried culture grown on autoclaved rice kernels. The growth on cereal grains is one of the most utilized method for the production of fungal biomass of bio-pesticides and is also fully compatible with organic farming and other forms of environmental friendly agriculture. The aphids were treated by dipping in a suspension containing two different dosage of fungal formulation (25 mg ml-1 or 25 g ml-1). The Colony Forming Unit/g value of the fungal formulation was 2.18 108. The strain affects the survival and the reproduction of treated aphids, but it interacts differently with the two aphid morphs. Scanning electron microscope observations point out a different distribution of the fungal formulation over the integument of the two treated morphs, with a higher amount of adhering formulation and faster rates of fungal germination on the winged cuticle. We therefore hypothesize a crucial role played by the cuticle in the different initial spore adhesion, retention and germination, considered as a most effective reason of the survival difference between the two morphs, after treatment by using fungal formulation. Histological analysis revealed that hyphae invaded the host hemocoel of a limited number of winged and wingless specimens, suggesting that the lethal action of formulation might be expressed independently from penetration. In terms of route of penetration, the analysis revealed that the strain entered only through the spiracles. The fungus was also transferred from sporulating colonies on cadavers to uninfected individuals. Our results suggested that this strain is a good candidate for a programme of bio-control against S. graminum and other aphid species.

2002 - Interactions between Onychiurus armatus and Trichoderma harzianum in take-all disease suppression in a simple experimental system [Articolo su rivista]
Sabatini, Maria Agnese; Grazioso, Pasqualina; C., Altomare; G., Innocenti
abstract

In a simple experimental system with wheat plants, interactions between the collembolan Onychiurus armatus and Trichoderma harzianum, a soil-borne fungus parasite of several plant pathogenic fungi, were studied in the presence of Gaeumannomyces graminis var. tritici, one of the most important foot and root fungal pathogens of cereals world-wide. Trichoderma harzianum was used according to two different modalities: fungal inoculum applied to seed or mixed with substrate. The isolate of T harzianum proved to be ineffective against the pathogenic fungus, independent of the application modality, as shown in the experiments where this fungus was used alone, whereas Collembola used alone significantly reduced disease severity. However, the mode by which harzianum was applied significantly influenced the disease control ability of Collembola. In fact, only when T harzianum was coated to seed were springtails able to reduce the disease caused by G. graminis var. tritici. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.

2002 - Interactions between Onychiurus armatus and Trichoderma harzianum in take-all disease suppression in a simple experimental system. [Relazione in Atti di Convegno]
Sabatini, Maria Agnese; Grazioso, Pasqualina; C., Altomare; G., Innocenti
abstract

In a simple experimental system with wheat plants, interactions between the collembolan Onychiurus armatus and Trichoderma harzianum, a soil-borne fungus parasite of several plant pathogenic fungi, were studied in the presence of Gaeumannomyces graminis var. tritici, one of the most important foot and root fungal pathogens of cereals world-wide. Trichoderma harzianum was used according to two different modalities: fungal inoculum applied to seed or mixed with substrate. The isolate of T. harzianum proved to be ineffective against the pathogenic fungus, independent of the application modality, as shown in the experiments where this fungus was used alone, whereas Collembola used alone significantly reduced disease severity. However, the mode by which T. harzianum was applied significantly influenced the disease control ability of Collembola. In fact, only when T. harzianum was coated to seed were springtails able to reduce the disease caused by G. graminis var. tritici.

2000 - Effects of a sulfonylurea herbicide on soil microarthropods [Articolo su rivista]
Rebecchi, Lorena; Sabatini, Maria Agnese; C., Cappi; Grazioso, Pasqualina; A., Vicari; G., Dinelli; Bertolani, Roberto
abstract

The short-term effects on soil microarthropods of the herbicide triasulfuron, belonging to the chemical class of sulfonylureas, were evaluated in two fields which had never been treated with sulfonylureas, and were cultivated with winter wheat. In particular, the effects of single applications at rates corresponding to two- (rate 2) and sixfold (rare 6) the recommended agricultural rare (7.5 g active ingredient ha(-1)) were analysed and compared with controls. The changes in the populations of the main groups of microarthropods were evaluated. Rate 2 had very low effects, whereas rate 6 produced a significant decrease in the number of microarthropods, Acarina and Collembola in the surface soil layer (0-7.5 cm). The Collembola were analysed at the species level. Statistical analysis revealed significant differences only for a few species, and only after treatment with the highest rate of triasulfuron. Finally, the results of the field tests were compared to those of laboratory tests carried out previously, which examined the effects of the same herbicide on a collembola species.

1997 - Laboratory and field approaches to evaluate the effects of the herbicide triasulfuron on Collembola. [Abstract in Rivista]
Rebecchi, Lorena; C., Cappi; Sabatini, Maria Agnese; Grazioso, Pasqualina; A., Guidi; A., Vicari; G., Dinelli; Bertolani, Roberto
abstract

The effects of the herbicide triasulfuron on Collembola are evaluated in laboratory and field studies.

1995 - La lavorazione del terreno e i suoi effetti sulle comunità di microartropodi del suolo [Relazione in Atti di Convegno]
Bertolani, Roberto; Sabatini, Maria Agnese; Rebecchi, Lorena; Grazioso, Pasqualina; B., Fratello
abstract

We performed a study on the long-term effects of three types of soil tillage practices and enrichment with two doses of nitrogen fertilizers on soil microartropods. The study carried out in two succesive yeras found no significance differences in the overall population densities of Acarina or Collembola to the species level revealed differences to tillage. it is important that in studeis on agroecosytems at least one of the principal soil micorarthropod taxa be analysed at level species.