Examinando por Materia "Entomopathogenic fungi"

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    Activity of two entomopathogenic fungi, molecularly identified, on bactericera cockerelli.
    (Universidad del Valle, 2017-06-30) Villegas Rodríguez, Fabiola; Díaz Gómez, Ovidio; Casas Flores, J. Sergio; Monreal Vargas, Clara Teresa; Tamayo Mejía, Fernando; Aguilar Medel, Sotero; Sociedad Colombiana de Entomología - Socolen; Universidad del Valle
    The potato psyllid Bactericera cockerelli affects solanaceous causes direct damage to crops in Mexico, as well as transmitting prokaryotic pathogens such as Candidatus Liberibacter solanacerum (psyllaurous). In the past, it has been controlled mainly using chemical products, while recent management strategies seek different strategies, including the use of enthomopathogenic fungi. The goal of this study was to evaluate the susceptibility of the potato psyllid to commercial and native Metarizhium anisopliae and Be. bassiana strains, and to determine the identity of these fungi through molecular techniques. Bioassays were done under laboratory conditions using the wild type (MA25) of anisopliae, the commercials strain (Metabich®, MA28), the Be. bassiana BB42 wild type strain, and the commercial strain Bassianil® BB09. Five different conidia concentrations were tested against third instar nymphs of Bactericera cockerelli, and their corresponding LC50 and LC95 were determined. The strains tested were pathogenic against the potato psyllid, with the highest virulence obtained using BB09 followed by BB42 and MA28. Using the highest concentrations of the strains, mortality varied between 90 and 100%, with the most virulent being BB09 with a LC50 of 2.99 x 104 conidia per ml, and the least virulent being MA25, with a LC50 of 6.34 x 105 conidia per ml. Previously, the Be. bassiana and M. anisopliae wild type strains were identified using conventional methods; this report confirms them through molecular techniques based on the cloning and sequencing of their rDNA 18S gene.
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    PublicaciónAcceso abierto
    Characterization of native isolates of Beauveria bassiana and its pathogenicity to Hypothenemus hampei, en Tabasco, Mexico.
    (Universidad del Valle, 2016-06-30) Gerónimo Torres, José del Carmen; Torres de La Cruz, Magdiel; Pérez de La Cruz, Manuel; Cruz Pérez, Aracely De la; Ortiz García, Carlos Fredy; Cappello García, Silvia
    In order to obtain native isolates of Beauveria bassiana with potential to control Hypothenemus hampei, 12 strains were isolated and characterized according to physiological and pathogenicity variables. Mycelia growth (MG), germination rate and conidial production (CP) in Sabouraud dextrose agar media + 0.1% of yeast extract (SDA+YE), were assessed at 25, 30 and 35 °C. In addition, the conidial production on rice was evaluated at 25 °C. There were differences (P < 0.001) in the MG of the isolates. The favorable temperature for MG ranged between 25 and 30 °C. The time required to 50% of conidial germination (TG50) ranged from 12.6 to 15.9 h, and the TG90 ranged from 16.9 to 61.5 h. The best TG50 and TG90 were obtained at 25 and 30 °C. The optimum temperature for germination, of the majority of the isolates, was 30 °C. There were differences (P < 0.001) on the PdC in the SDA+YE media, and the optimum temperature for the production of conidia was 25 °C. Thus, there were differences (P < 0.001) in the production of conidia in rice. The pathogenic effectiveness of the isolates of B. bassiana on H. hampei was 100%, to the 144 h. Letal time to kill 50% of the population (TL50) ranged from 71.8 to 104 h; as well as, the TL90 ranged from 91.8 to 132.8 h. Native strains BbTcf9, BbTcf5 and BbTcf1 were selected for its evaluation under field conditions.
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    PublicaciónAcceso abierto
    Susceptibility of Sphenarium purpurascens purpurascens (Orthoptera: Pyrgomorphidae) instars to a commercial strain of Metarhizium acridum (Hypocreales: Clavicipitaceae) in Michoacan, Mexico.
    (Universidad del Valle, 2019-12-31) Quesada Béjar, Venecia; Nájera Rincón, Miguel B.; Reyes Novelo, Enrique; González Esquivel, Carlos E.; Sociedad Colombiana de Entomología - Socolen; Universidad del Valle; Montoya Lerma, James
    The objective of this study was to evaluate the performance of a commercial strain of the entomopathogenic fungi Metarhizium acridum, on the different instars of the grasshopper pest Sphenarium purpurascens purpurascens, as well as its sporulation via bioassays under laboratory conditions, in Michoacan, Mexico. The most susceptible instars were nymphs one, two and four, with an average survival time of less than 6.91 days. The least susceptible was the adult, with a survival time of 8.36 days. The instars with the highest post mortem sporulation were nymphs one, two and three. A moderate negative association was registered between S. p. purpurascens and the sporulation of M. acridum, in advanced instars (nymph 4 and adult), in which sporulation was lower compared to early instars. All instars showed survival rates below 5 %, so M. acridum can be considered to be a viable option for controlling this pest in the field.