Examinando por Materia "Bioassays"

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    PublicaciónAcceso abierto
    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
    Impact of resistance to fenitrothion and esfenvalerate on the control of Rhyzopertha dominica (Coleoptera: Bostrichidae) in stored wheat.
    (Universidad del Valle, 2020-12-26) Vásquez Castro, Javier Alberto; Casadei De Baptista, Gilberto; Dias Gadanha Jr., Casimiro; Bracho Pérez, Julio Cesar; Sociedad Colombiana de Entomología - Socolen; Universidad del Valle; Montoya Lerma, James
    Insecticides resistance can significantly compromise the control programs of Rhyzopertha dominica (Coleoptera: Bostrichidae), one of the main wheat pests in warehouses. The objectives of this work were to study the occurrence of resistance to fenitrothion and esfenvalerate in two Brazilian populations of R. dominica from Santa Rosa (SR lineage) and Campo Grande (CG lineage), as well as the insecticidal effect and residual action of these insecticides when used alone or as a mixture in stored wheat. The application system was calibrated to provide grain treatment at theoretical concentrations of 10 and/or 0.5 mg kg-1 fenitrothion and esfenvalerate, respectively. By comparing the fitted mortality curves for lineages within insecticides, as well as insecticides within lineages significant differences were observed in all cases. Esfenvalerate was ineffective in controlling R. dominica. The SR lineage of R. dominica was more resistant to the insecticides tested than the CG lineage. The number of individuals in the F1 offspring of R. dominica was dependent on the lineage, insecticide, and on the time after the application of insecticide. In the untreated grains (control), the CG lineage had a greater number of progeny than the SR lineage, while the opposite was verified in the grains treated. Fenitrothion and esfenvalerate are not useful for the control of R. dominica. Factors influencing control of R. dominica are discussed in this work.
  • Miniatura
    PublicaciónAcceso abierto
    Virulence of blastospores of Isaria fumosorosea natives of northeastern Mexico on Anastrepha ludens (Diptera: Tephritidae).
    (Universidad del Valle, 2018-12-31) Gandarilla Pacheco, Fatima Lizeth; Elías Santos, Myriam; Flores González, María del Socorro; Luna Santillana, Erick de Jesús de; Quintero Zapata, Isela; Sociedad Colombiana de Entomología - Socolen; Universidad del Valle; Montoya Lerma, James
    Anastrepha ludens is one of the pests that seriously affects fruit production in Mexico and other Neotropical countries. The aim of this study was to evaluate the virulence and effects of four native isolates and a collected strain of Isaria fumosorosea on the metamorphosis of A. ludens through the use of bioassays under laboratory conditions [25 ± 2 °C; 60 ± 5 % (HR); 12:12 h (L: O)]. Larvae and pupae were exposed to 1 × 108 blastospores/ ml using two different methods: direct spraying and spraying of soil. The isolates HIB-23 and HIB-30 showed the highest mortality on A. ludens when applied using the direct spraying method on larvae (84 %), while the isolate HIB-19 showed the highest percentage of interruption of the metamorphosis (43 %) of A. ludens when applied through the method of direct spraying on pupae. The results show that A. ludens is susceptible to the attack of I. fumosorosea, which causes the disruption of its life cycle.