Examinando por Autor "Caicedo, Ana Milena"

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  • Publicación
    Acceso abierto
    Evaluación de la patogenicidad de Xenorhabdus spp. nativos en Colombia
    (2014-07) Guerra-Sierra, Beatriz Elena; Chacón, Julie Giovanna; Muñoz Flórez, Jaime Eduardo; Caicedo, Ana Milena
    Xenorhabdus and Photorhabdus bacteria are symbiotically associated with nematodes of the Steinernematidae and Heterorhabditidae families respectively. They are characterized by producing a complex of substances such as toxins, antibiotics and extracellular enzymes that kill insects. In order to select the most pathogenic nematodes and antibiotic production level, it was propose to evaluate the pathogenicity of 13 native isolates. Bacteria were isolated from infective juveniles (JIS) by direct macerated, cultured on selective media (NBTA and MacConkey) and described phenotypic and biochemically. The pathogenicity was evaluated on the last instar larvae of G. mellonella, using serial dilutions of the bacterial inoculum with a concentration of 104cel/ml. The mortality rate was registered at 12, 24 and 48 hours and the colony forming units (CFU) in NBTA agar in the same intervals of time. The data were analyzed by variance analysis and mean comparison by Duncan test. Biochemical and enzymatic tests were positive for the genus Xenorhabdus. The results showed that the isolates UNPX04, UNPX15 from agricultural soils of Florida -Risaralda and Llano Bajo- Valle del Cauca respectively, caused 100% of mortality at 12 and 24 hours in contrast with seven isolations that caused only 70% of mortality.
  • Publicación
    Acceso abierto
    Evaluación de la patogenicidad y virulencia de aislados de Beauveria sp. En el control de Pseudacysta perseae (Heid), inductora de pestalotiopsis en palma aceitera (Elaeis guineensis Jacq) en la region caribe de Nicaragua.
    (Bucaramanga : Universidad de Santander, 2019, 2019-12-16) Rueda Cediel, Sergio David; Guerra-Sierra, Beatriz Elena; Muñoz Cabezas, Orlando Arturo; Caicedo, Ana Milena
    The oil palm is the most profitable oilseed plant in the agribusiness, because of the characteristics of its cultivation it is attacked by pests that generate or induce different diseases, one of them is pestalotiopsis, a disease of great economic impact, generates losses of up to 40% in production. In Nicaragua, the disease-inducing insect is Pseudacysta perseae, its control proposes biological control because it reduces the contamination presented by using chemical insecticides. Therefore, the purpose of the work was to isolate fungi from P. perseae corpses, for the identification, selection and evaluation of their pathogenic and virulent capacity on P. perseae adults. For this, the bed bug was raised in pre-nursery palms, which were infested with P. perseae., Fungal inoculums of the three isolates were prepared at different concentrations between 1.9x107 to 4.2x107 conidia / mL. For virulence and pathogenicity tests, six treatments, belonging to the three recovered microorganisms, a mixed treatment (equal mixing of the inoculums of the three isolates) were evaluated, to know the overall behavior of the isolates, negative control (water + tween 80 to 0.1%) and finally positive control (Hirsutella sp) taken into account for this investigation due to its entomopathogenic characteristic, provided by Dr. Beatriz Guerra, four repetitions were performed, sprinkling the inoculum on the palm leaflet applying 1.3 mL and concentration between 1.9x107 to 4.2x107 conidia / mL. Three times 24, 48 and 72 hours were evaluated. Finally, it was concluded that treatments number two (Beauveria sp) and number four (mixed treatment) were the most virulent with a mortality percentage of 70.8% and 69.5% respectively at 48 hours of evaluation. Finally, all the treatments evaluated have pathogenicity after 72 hours of the evaluation.