The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform

Drion G Boucias - One of the best experts on this subject based on the ideXlab platform.

  • the insecticidal protein hirsutellin a from the mite fungal pathogen Hirsutella thompsonii is a ribotoxin
    Proteins, 2008
    Co-Authors: Elias Herrerogalan, Drion G Boucias, Javier Lacadena, Alvaro Martinez Del Pozo, Nieves Olmo, Mercedes Onaderra, Jose G Gavilanes
    Abstract:

    The mite fungal pathogen Hirsutella thompsonii produces a single polypeptide chain, insecticidal protein named hirsutellin A (HtA) that is composed of 130 amino acid residues. This protein has been purified from its natural source and produced as a recombinant protein in Escherichia coli. Spectroscopic analysis has determined that the two protein forms are indistinguishable. HtA specifically inactivates ribosomes and produces the α-fragment characteristic of ribotoxin activity on rRNA. Behaving as a cyclizing ribonuclease, HtA specifically cleaves oligonucleotides that mimick the sarcin/ricin loop of the ribosome, as well as selected polynucleotides and dinucleosides. HtA interacts with phospholipid membranes as do other ribotoxins. As a consequence of its ribonuclease activity and its ability to interact with cell membranes, HtA exhibits cytotoxic activity on human tumor cells. On the basis of these results, HtA is considered to be a member of the ribotoxin group of proteins, although it is significantly smaller (130 aa) than all known ribotoxins that are composed of 149/150 amino acids. Ribotoxins are members of a larger family of fungal ribonucleases whose members of smaller size (100/110 aa) are not cytotoxic. Thus, the characterization of the fungal ribotoxin HtA represents an important milestone in the study of the diversity and the function of fungal ribonucleases. Proteins 2008. © 2008 Wiley-Liss, Inc.

  • genetic diversity of Hirsutella thompsonii isolates from thailand based on aflp analysis and partial beta tubulin gene sequences
    Genetics and Molecular Biology, 2006
    Co-Authors: Myrian S Tigano, Saowanit Maimala, Byron J Adams, Drion G Boucias
    Abstract:

    Amplified fragment length polymorphism (AFLP) was used to investigate polymorphism among 43 Hirsutella thompsonii isolates (33 from Thailand) obtained from various mite species. The outgroups were an unidentified Hirsutella isolate along with Hirsutella nodulosa and Hirsutella kirchneri. Phylogenetic analyses of the AFLP data showed significant variation among isolates and the existence of three H. thompsonii clades. We also investigated the isolates using PCR with specific primers for the Hirsutella exotoxin gene Hirsutelin A (HtA) and 18 of these isolates were used for sequencing of the partial -tubulin gene. Phylogenetic analyses of -tubulin sequences showed two distinct H. thompsonii clades, one of which included AFLP clades I and II. For both markers grouping of the H. thompsonii isolates was not related to either host mite species or geographical origin, although for the HtA gene one clade contained only isolates with no detectable HtA band. These results confirm the high intraspecific polymorphism of H. thompsonii, and maximum likelihood analysis showed no monophyletic group within this species. To refine the taxonomy of this genus other studies should be undertaken using additional molecular markers and several other Hirsutella isolates.

  • pathogenicity of metarhizium anisopliae var acridum to the false spider mite brevipalpus phoenicis acari tenuipalpidae
    Florida Entomologist, 2005
    Co-Authors: Bonifacio P Magalhaes, Drion G Boucias, J C V Rodrigues, Carl C Childers
    Abstract:

    The flat mite, Brevipalpus phoenicis (Geijkes), is a polyphagous pest found in many subtropical and tropical regions of the world (Childers et al. 2003). Brevipalpus phoenicis is recognized as the most economically harmful virus vector species in citrus areas where Citrus leprosis Virus (CiLV) has been reported. So far, chemical sprays have been the main approach adopted to control the mite in citrus (Rodrigues & Machado 2003). Otherwise, fungal pathogens are frequently found causing diseases and epizootics in mite populations (Alves 1998; Van Der Geest et al. 2000). Recently, the potential to control Brevipalpus populations by spraying with the fungus Hirsutella thompsonii Fisher was suggested (Rosas-Acevedo & Sampedro 2000; Rossi 2002). However, the development of H. thompsonii as a bio-acaricide has been hampered by difficulties in mass producing aerial conidia. In contrast, the entomopathogenic fungus Metarhizium anisopliae var. acridum Driver & Milner is easily produced in large scale and has been developed as a mycoinsecticide in several countries (Magalhaes et al. 2000; Lomer et al. 2001). This fungus is tolerant of high temperatures, an important characteristic for pathogens developed for tropical agroecosystems. We studied the pathogenicity of M. anisopliae var. acridum against B. phoenicis to evaluate its potential use as an acaricide. Mites used in this study were 5-15 days old adult females derived from clonal lineage established from a single female isolated from a mite colony collected from citrus in Plant City, Florida (Rodrigues et al. 2004). The fungus assayed was the isolate CG423 of M. anisopliae var. acridum , produced on SDAY medium, harvested, and dried according to Magalhaes & Boucias (2004). The viability of the conidia used in the bioassays was determined by plate assay to be >95%. The bioassay unit was a 90-mm diameter Petri dish containing a 60-mm diameter plate glued to the bottom. A 1.5-cm diameter circular leaf arena clipped from Ligustrum lucidum Aiton was placed over a layer of cotton wool which was saturated with water. Twenty mites were transferred to the leaf arena. Two h later the pathogen was applied at a concentration of 10 8

  • Exudate from sporulating cultures of Hirsutella thompsonii inhibit oviposition by the two-spotted spider mite Tetranychus urticae
    Experimental & Applied Acarology, 2003
    Co-Authors: José Luis Rosas-acevedo, Drion G Boucias, Roberto Lezama, Kelly Sims, Alfonso Pescador
    Abstract:

    The acaricidal mycopathogen Hirsutella thompsonii has been found to secrete metabolites that are active against female Tetranychus urticae . Specifically, the rose-colored exudate produced on sporulating cultures of Mexican HtM120I strain sterilized female spider mites in a dose-dependent fashion. Topical application of the exudate resulted in a 100% reduction in mite fecundity over the initial six days of experimentation. Depending upon the exudate dosage, mites partially recovered within 3 and 6 d post-treatment and produced a limited number of eggs. The spider mite active HtM120I exudate contained less detectable HtA toxin than the HtM120I broth filtrate, and it was innocuous when injected into the greater wax moth Galleria mellonella L. larvae. Broth filtrates of HtM120I cultures, although toxic to assayed G. mellonella larvae, did not inhibit mite oviposition to the degree or duration of the exudate preparations. These findings suggest that the factor responsible for suppressing oviposition in female spider mites is linked to the sporulation process and is distinct from the well-characterized HtA produced by vegetative cells.

  • Hirsutella thompsonii and metarhizium anisopliae as potential microbial control agents of varroa destructor a honey bee parasite
    Journal of Invertebrate Pathology, 2002
    Co-Authors: L H B Kanga, Rosalind R James, Drion G Boucias
    Abstract:

    Abstract The potential of Hirsutella thompsonii Fisher and Metarhizium anisopliae (Metschinkoff) as biological control agents of the parasitic mite, Varroa destructor Anderson and Trueman was evaluated in the laboratory and in observation hives. In the laboratory, time required for 90% cumulative mortality of mites (LT90) was 4.16 (3.98–4.42) days for H. thompsonii and 5.85 (5.48–7.43) days for M. anisopliae at 1.1×103 conidia mm−2. At a temperature ( 34±1 ° C ) similar to that of the broodnest in a honey bee colony, Apis mellifera L., H. thompsonii [LC90=9.90×101 (5.86–19.35) conidia mm−2 at Day 7] and M. anisopliae [LC90=7.13×103 (2.80–23.45) conidia mm−2 at Day 7] both showed significant virulence against V. destructor. The applications of H. thompsonii to observation hives resulted in significant mortality of mites, and reduction of the number of mites per bee 21 and 42 days post-treatments. The treatments did not significantly affect the mite population in sealed brood. However, the fungus must have persisted because infected mites were still observed [82.97±(0.6)%] 42 days post-treatment. In addition, the fungus was found to sporulate on the host. A small percentage [2.86±(0.2)%] of dead mites found in the control hives also showed fungal infection, suggesting that adult bees drifted between hives and disseminated the fungus. H. thompsonii was harmless to the honey bees at the concentrations applied and did not have any deleterious effects on the fecundity of the queens. Microbial control with fungal pathogens provides promising new avenues for control of V. destructor and could be a useful component of an integrated pest management program for the honey bee industry.

Clayton W. Mccoy - One of the best experts on this subject based on the ideXlab platform.

  • extraction and characterization of the insecticidal toxin hirsutellin a produced by Hirsutella thompsonii var thompsonii
    Experimental Mycology, 1995
    Co-Authors: Weizhen Liu, Drion G Boucias, Clayton W. Mccoy
    Abstract:

    Abstract Liu, W.-Z., Boucias, D. G., and McCoy, C. W. 1995. Extraction and characterization of the insecticidal toxin hirsutellin A produced by Hirsutella thompsonii var. thompsonii. Experimental Mycology 19, 254-262. Hirsutellin A (HtA) produced by Hirsutella thompsonii var. thompsonii (strain JAB-04) was extracted and purified using a combination of ion-exchange, gel-permeation, and immunoaffinity chromatography. The identity of the purified HtA was confirmed by amino acid analysis and N-terminal sequencing. Monoclonal antibodies prepared against HtA were capable of detecting 25-50 ng of HtA by direct sandwich ELISA. In addition, utilizing Western blot methods, the antibodies were shown to be specific to HtA. The production of HtA was monitored during submerged fermentation. The peak level of exocellular HtA (13-14 μg/ml) was during the late exponential growth phase (39-45 h), determined by utilizing a combination of densitometric analysis of the 16.3-kDa bands on SDS-PAGE gels and ELISA. HtA production was directly correlated with mycelial growth. Twenty-one-hour culture filtrates were highly toxic to larvae of the greater wax moth. Pure HtA at a final concentration of 40 pmol was highly toxic to Galleria mellonella larvae.

  • effect of copper sprays on the population dynamics of the citrus rust mite phyllocoptruta oleivora acari eriophyidae and its fungal pathogen Hirsutella thompsonii
    Proceedings of the Florida State Horticultural Society, 1995
    Co-Authors: Clayton W. Mccoy
    Abstract:

    Populations of citrus rust mite (CRM), Phyllocoptruta oleivora (Ashmead), and its fungal pathogen, Hirsutella thompsonii Fisher, were monitored weekly for 2 years on leaves of Marsh grapefruit trees sprayed at specified time intervals with a formulation of copper hydroxide containing 50% metallic copper. Seasonal fluctuations in CRM population density were similar from year to year but differed between treatments. From early May to mid-July, mite population densities were always lower on copper-treated leaves compared to the untreated controls. According to laboratory studies, the lower CRM population density in copper treatments was affected by reduced fecundity rather than increased adult mortality or reduced egg eclosion. Epizootics of H. thompsonii occurred in the unsprayed control in July both years. The incidence of fungal pathogen in mite populations was density-dependent and was affected by the time of copper treatment. Copper sprays applied before, during or after mite populations peaked in summer did not prevent but influenced the magnitude of the epizootic by causing a reduction in both CRM populations and the incidence of infected mites. Copper sprays did not incite a resurgence of the CRM populations in the fall.

  • toxicity and pathology of crude broth filtrate produced by Hirsutella thompsonii var thompsonii in shake culture
    Journal of Invertebrate Pathology, 1993
    Co-Authors: A. Vey, Isabelle Mazet, Jean Marie Quiot, Clayton W. Mccoy
    Abstract:

    Abstract Metabolic products secreted by the fungal mycelia of Hirsutella thompsonii var. thompsonii (CBS 556.77D) in a defined culture broth in shake culture were tested for toxicity to Galleria mellonella larvae and Drosophila melanogaster adults via injection and per os application, respectively. In addition, the toxic effect of broth filtrate was observed in vitro in a cell line of Bombyx mori . Czapek-Dox broth fortified with 1% yeast extract stimulated more rapid mycelial growth and correspondingly more toxin production in time. At 25-30°C, metabolic toxin(s) was detected in broth via bioassay at about 4-5 days postinoculation when mycelial biomass reached 5 mg/ml (dry wt). At these temperatures, biological activity of the filtrate peaked at about 8-10 days when mycelial growth reached a maximum (10 mg/ml, dry wt). This suggests a positive relationship between toxic metabolite and mycelial production. After 10 days, the toxicity of the filtrate appeared to decline gradually. Pathogenicity symptoms of the metabolites developed slowly in both G. mellonella and D. melanogaster . Early signs of lethargy appeared at 4 days postinjection and cumulative mortality of G. mellonella larvae was low after 1 week; however, the percentage of mortality reached 98-100% after 14 days. At death, G. mellonella larvae displayed small dark spots on a brownish cuticle. Histopathological effects were observed in the larval midgut, malpighian tubules, hypodermis, fat body, hemocytes, muscle, and silk glands. Cellular change consisted of pycnosis of the nucleus and a reduction in cytoplasm density. Highest mortality (78.8%) to adult D. melanogaster occurred after 10 days post-treatment. A strong cytotoxic effect was detected in B. mori cells after 24 hr.

Laura Sampedro Rosas - One of the best experts on this subject based on the ideXlab platform.

  • variability of Hirsutella thompsonii strains isolated from phytophagous mites from three terrestrial systems in the state of colima mexico
    Revista Mexicana de Biodiversidad; Vol 77 No 001, 2011
    Co-Authors: Jose Luis Rosas Acevedo, Laura Sampedro Rosas
    Abstract:

    BETWEEN 1999 AND 2004, TEN STRAINS OF THE FUNGUS Hirsutella thompsonii FISHER WERE ISOLATED FROM INFECTED MITES, IN 9 LOCALITIES OF 3 OF THE 11 TERRESTRIAL SYSTEMS FOUND IN THE STATE OF COLIMA, MEXICO: COASTAL PLAIN OF TECOMAN, COASTAL PLAIN OF CUYUTLAN, AND THE VALLEY OF THE ARMERIA RIVER. OF THE 10 STRAINS, 5 BELONG TO VAR. thompsonii, WHOSE GROWTH IS FLUFFED MYCELIAL, SLIGHTLY ELEVATED, GRAY TO GREENISH GRAY, AND 5 TO VAR. SINEMATOSA, WITH A FL AT APPEARANCE, WHITE TO YELLOW. THE HOSTS WERE TWO-SPOTTED SPIDER MITE (TETRANICHUS URTICAE), ERIOPHIDAE (ACERIA GUERRERONIS AND PHYLLOCOPTRUTA OLEIVORA) AND BREVIPALPIDAE (BREVIPALPUS PHOENICIS), CITRUS SPP. BEING THE HOST OF THE MITES IN 8 OF THE 10 ISOLATIONS. OF THE 10 STRAINS, ONLY ONE HTM130 STRAIN OF H. thompsonii VAR. thompsonii DISPLAYED EXUDATE FORMATION IN THE SPORULATIVE PHASE, CHARACTERISTIC THAT GIVES GREATER POTENTIAL FOR IMPLEMENTATION IN MANAGEMENT STRATEGIES FOR THE CONTROL OF PHYTOPHAGOUS MITES. STRAIN COLORATION AND GROWTH ARE NOT CORRELATED WITH THE TERRESTRIAL SYSTEM WHERE THEY WERE FOUND, NOR TO PREVAILING CLIMATIC CONDITIONS. THIS CONTRIBUTION DEMONSTRATES THE IMPORTANCE OF ASSESSING THE PRESENCE OF NATIVE NATURAL ENEMIES, BEFORE INTRODUCING COMMERCIAL MICROORGANISMS OR ISOLATIONS FROM ELSEWHERE SO AS NOT TO AFFECT THE NATURAL REGULATORY SYSTEMS.

  • variabilidad de cepas de Hirsutella thompsonii a partir de acaros fitofagos en tres sistemas terrestres del estado de colima mexico
    Revista Mexicana De Biodiversidad, 2006
    Co-Authors: Jose Luis Rosas Acevedo, Laura Sampedro Rosas
    Abstract:

    ENTRE 1999 Y 2004 SE OBTUVIERON DIEZ CEPAS DEL HONGO Hirsutella thompsonii FISHER, A PARTIR DE ACAROS INFECTADOS, EN 9 LOCALIDADES DE 3 DE LOS 11 SISTEMAS TERRESTRES QUE TIENE EL ESTADO DE COLIMA, MEXICO: LLANURA COSTERA DE TECOMAN, LLANURA COSTERA DE CUYUTLAN Y VALLE DEL RIO ARMERIA. DE LAS 10 CEPAS, 5 PERTENECEN A LA VARIEDAD thompsonii QUE ES DE CRECIMIENTO MICELIAL MULLIDO, LIGERAMENTE ELEVADO, DE COLOR GRIS A GRIS VERDOSO, Y 5 A LA VARIEDAD SINEMATOSA SAMSON, MCCOY Y O”DONNELL, DE APARIENCIA PLANA Y COLORACION BLANCO A AMARILLO. LOS HOSPEDANTES FUERON ARANA ROJA (TETRANYCHUS URTICAE KOCH), ERIOFIDOS (ACERIA GUERRERONIS KEIFER Y PHYLLOCOPTRUTA OLEIVORA ASHMEAD) Y BREVIPALPIDOS (BREVIPALPUS PHOENICIS GEIJKES) SOBRE CITRICOS COMO HOSPEDERO DE 8 DE LOS 10 AISLAMIENTOS. DE ELLOS, SOLO LA CEPA HTM130 DE H. thompsonii VAR. thompsonii PRESENTO FORMACION DE EXUDADOS EN LA FASE ESPORULATIVA, CARACTERISTICA QUE LE DA MAYOR POTENCIAL DE MANEJO EN ESTRATEGIAS PARA EL CONTROL DE ACAROS FITOPATOGENOS. EL TIPO DE CRECIMIENTO Y LA COLORACION DE LAS CEPAS NO SE CORRELACIONAN CON EL SISTEMA TERRESTRE DONDE SE ENCONTRARON, NI CON LAS CONDICIONES CLIMATICAS IMPERANTES EN ELLOS. LA PRESENTE CONTRIBUCION DEMUESTRA LA IMPORTANCIA DE VALORAR LA PRESENCIA DE ENEMIGOS NATURALES AUTOCTONOS PARA GARANTIZAR UN MEJOR ESTABLECIMIENTO BAJO LAS CONDICIONES AGROCLIMATICAS DE LA REGION DONDE SE PRETENDA UTILIZARLOS, Y ANTES DE INTRODUCIR MICROORGANISMOS COMERCIALES OAISLAMIENTOS DE OTROS SITIOS PARA NO AFECTAR LOS SISTEMAS NATURALES DE REGULACION.

Jose Luis Rosas Acevedo - One of the best experts on this subject based on the ideXlab platform.

  • esporulacion y metabolitos de Hirsutella thompsonii fisher
    2012
    Co-Authors: Jose Luis Rosas Acevedo, Ana Yolanda Rosas Acevedo Audel Sanchez Infante
    Abstract:

    El control biologico de acaros y otros artropodos es posible con el uso de hongos como Hirsutella thompsonii, utilizando conidios (esporas) y sus metabolitos secundarios. En la actualidad crece el interes por conocer la relacion patogeno-hospedero y la reproduccion masiva de estos microorganismos para su utilidad en la regulacion de las plagas y disminuir el consumo y aplicacion de productos quimicos tanto en areas agricolas, como en los jardines y vegetacion circundante de los centros turisticos. El aislamiento, seleccion y manejo de estos hongos son una alternativa amigable con el ambiente, que disminuye el impacto por quimicos sinteticos en el suelo, el agua, el aire y en las personas que son expuestas directa e indirectamente a estos agentes contaminantes.

  • variability of Hirsutella thompsonii strains isolated from phytophagous mites from three terrestrial systems in the state of colima mexico
    Revista Mexicana de Biodiversidad; Vol 77 No 001, 2011
    Co-Authors: Jose Luis Rosas Acevedo, Laura Sampedro Rosas
    Abstract:

    BETWEEN 1999 AND 2004, TEN STRAINS OF THE FUNGUS Hirsutella thompsonii FISHER WERE ISOLATED FROM INFECTED MITES, IN 9 LOCALITIES OF 3 OF THE 11 TERRESTRIAL SYSTEMS FOUND IN THE STATE OF COLIMA, MEXICO: COASTAL PLAIN OF TECOMAN, COASTAL PLAIN OF CUYUTLAN, AND THE VALLEY OF THE ARMERIA RIVER. OF THE 10 STRAINS, 5 BELONG TO VAR. thompsonii, WHOSE GROWTH IS FLUFFED MYCELIAL, SLIGHTLY ELEVATED, GRAY TO GREENISH GRAY, AND 5 TO VAR. SINEMATOSA, WITH A FL AT APPEARANCE, WHITE TO YELLOW. THE HOSTS WERE TWO-SPOTTED SPIDER MITE (TETRANICHUS URTICAE), ERIOPHIDAE (ACERIA GUERRERONIS AND PHYLLOCOPTRUTA OLEIVORA) AND BREVIPALPIDAE (BREVIPALPUS PHOENICIS), CITRUS SPP. BEING THE HOST OF THE MITES IN 8 OF THE 10 ISOLATIONS. OF THE 10 STRAINS, ONLY ONE HTM130 STRAIN OF H. thompsonii VAR. thompsonii DISPLAYED EXUDATE FORMATION IN THE SPORULATIVE PHASE, CHARACTERISTIC THAT GIVES GREATER POTENTIAL FOR IMPLEMENTATION IN MANAGEMENT STRATEGIES FOR THE CONTROL OF PHYTOPHAGOUS MITES. STRAIN COLORATION AND GROWTH ARE NOT CORRELATED WITH THE TERRESTRIAL SYSTEM WHERE THEY WERE FOUND, NOR TO PREVAILING CLIMATIC CONDITIONS. THIS CONTRIBUTION DEMONSTRATES THE IMPORTANCE OF ASSESSING THE PRESENCE OF NATIVE NATURAL ENEMIES, BEFORE INTRODUCING COMMERCIAL MICROORGANISMS OR ISOLATIONS FROM ELSEWHERE SO AS NOT TO AFFECT THE NATURAL REGULATORY SYSTEMS.

  • variabilidad de cepas de Hirsutella thompsonii a partir de acaros fitofagos en tres sistemas terrestres del estado de colima mexico
    Revista Mexicana De Biodiversidad, 2006
    Co-Authors: Jose Luis Rosas Acevedo, Laura Sampedro Rosas
    Abstract:

    ENTRE 1999 Y 2004 SE OBTUVIERON DIEZ CEPAS DEL HONGO Hirsutella thompsonii FISHER, A PARTIR DE ACAROS INFECTADOS, EN 9 LOCALIDADES DE 3 DE LOS 11 SISTEMAS TERRESTRES QUE TIENE EL ESTADO DE COLIMA, MEXICO: LLANURA COSTERA DE TECOMAN, LLANURA COSTERA DE CUYUTLAN Y VALLE DEL RIO ARMERIA. DE LAS 10 CEPAS, 5 PERTENECEN A LA VARIEDAD thompsonii QUE ES DE CRECIMIENTO MICELIAL MULLIDO, LIGERAMENTE ELEVADO, DE COLOR GRIS A GRIS VERDOSO, Y 5 A LA VARIEDAD SINEMATOSA SAMSON, MCCOY Y O”DONNELL, DE APARIENCIA PLANA Y COLORACION BLANCO A AMARILLO. LOS HOSPEDANTES FUERON ARANA ROJA (TETRANYCHUS URTICAE KOCH), ERIOFIDOS (ACERIA GUERRERONIS KEIFER Y PHYLLOCOPTRUTA OLEIVORA ASHMEAD) Y BREVIPALPIDOS (BREVIPALPUS PHOENICIS GEIJKES) SOBRE CITRICOS COMO HOSPEDERO DE 8 DE LOS 10 AISLAMIENTOS. DE ELLOS, SOLO LA CEPA HTM130 DE H. thompsonii VAR. thompsonii PRESENTO FORMACION DE EXUDADOS EN LA FASE ESPORULATIVA, CARACTERISTICA QUE LE DA MAYOR POTENCIAL DE MANEJO EN ESTRATEGIAS PARA EL CONTROL DE ACAROS FITOPATOGENOS. EL TIPO DE CRECIMIENTO Y LA COLORACION DE LAS CEPAS NO SE CORRELACIONAN CON EL SISTEMA TERRESTRE DONDE SE ENCONTRARON, NI CON LAS CONDICIONES CLIMATICAS IMPERANTES EN ELLOS. LA PRESENTE CONTRIBUCION DEMUESTRA LA IMPORTANCIA DE VALORAR LA PRESENCIA DE ENEMIGOS NATURALES AUTOCTONOS PARA GARANTIZAR UN MEJOR ESTABLECIMIENTO BAJO LAS CONDICIONES AGROCLIMATICAS DE LA REGION DONDE SE PRETENDA UTILIZARLOS, Y ANTES DE INTRODUCIR MICROORGANISMOS COMERCIALES OAISLAMIENTOS DE OTROS SITIOS PARA NO AFECTAR LOS SISTEMAS NATURALES DE REGULACION.

Isabelle Mazet - One of the best experts on this subject based on the ideXlab platform.

  • toxicity and pathology of crude broth filtrate produced by Hirsutella thompsonii var thompsonii in shake culture
    Journal of Invertebrate Pathology, 1993
    Co-Authors: A. Vey, Isabelle Mazet, Jean Marie Quiot, Clayton W. Mccoy
    Abstract:

    Abstract Metabolic products secreted by the fungal mycelia of Hirsutella thompsonii var. thompsonii (CBS 556.77D) in a defined culture broth in shake culture were tested for toxicity to Galleria mellonella larvae and Drosophila melanogaster adults via injection and per os application, respectively. In addition, the toxic effect of broth filtrate was observed in vitro in a cell line of Bombyx mori . Czapek-Dox broth fortified with 1% yeast extract stimulated more rapid mycelial growth and correspondingly more toxin production in time. At 25-30°C, metabolic toxin(s) was detected in broth via bioassay at about 4-5 days postinoculation when mycelial biomass reached 5 mg/ml (dry wt). At these temperatures, biological activity of the filtrate peaked at about 8-10 days when mycelial growth reached a maximum (10 mg/ml, dry wt). This suggests a positive relationship between toxic metabolite and mycelial production. After 10 days, the toxicity of the filtrate appeared to decline gradually. Pathogenicity symptoms of the metabolites developed slowly in both G. mellonella and D. melanogaster . Early signs of lethargy appeared at 4 days postinjection and cumulative mortality of G. mellonella larvae was low after 1 week; however, the percentage of mortality reached 98-100% after 14 days. At death, G. mellonella larvae displayed small dark spots on a brownish cuticle. Histopathological effects were observed in the larval midgut, malpighian tubules, hypodermis, fat body, hemocytes, muscle, and silk glands. Cellular change consisted of pycnosis of the nucleus and a reduction in cytoplasm density. Highest mortality (78.8%) to adult D. melanogaster occurred after 10 days post-treatment. A strong cytotoxic effect was detected in B. mori cells after 24 hr.

  • recherches sur les hirsutellines toxines proteiques produites par Hirsutella thompsonii fisher champignon pathogene d acariens phytophages
    1992
    Co-Authors: Isabelle Mazet
    Abstract:

    Le champignon, Hirsutella thompsonii, pathogene d'acariens phytophages, produit et excrete au moins deux types de toxines proteiques: l'hirsutelline a separee a l'etat pur et la ou les hirsutellines b incompletement purifies. L'hirsutelline a est un monomere d'un poids moleculaire de 15 kda et d'un phi de 10,5. Sa composition en acides amines et la sequence des 34 premiers acides amines de l'extremite n-terminale ont ete determinees. Les sources brutes et l'hirsutelline a exercent une action insecticide non seulement par inoculation, mais aussi un effet letal per os, et peut etre en partie par contact, chez des insectes lepidopteres et dipteres, et chez des acariens comme phyllocoptruta oleivora. L'effet de l'hirsutelline a au niveau tissulaire et cellulaire a ete caracterise chez galleria mellonella et en cultures cellulaires. Les etudes histopathologiques ont revele de fortes alterations de tubes de malpighi et du mesenteron. Les lesions ultrastructurales consistent en une evolution pycnotique du noyau, une alteration des mitochondries et des changements au niveau de la bordure en brosse des cellules epitheliales. L'action caracteristique des metabolites d'h. thompsonii sur les muscles apparait comme la consequence de proprietes specifiques de la ou des hirsutellines b. L'hirsutelline a exerce aussi un effet antiviral sur des baculovirus resultant de l'inhibition de la synthese des proteines virales