Ciencias Agropecuarias

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    Evaluación del efecto en las fases móviles de Tetranychus urticae y Eotetranychus lewisi en el rendimiento fotosintético en fresa (Fragaria vesca)
    (2024-02) Carrera Carrera Washington Edmundo; Santana Mayorga, Rita Cumandá
    The present research was developed at the technical university of Ambato Faculty of Agricultural Sciences Querochaca Experimental Farm with the purpose of evaluating the effect on the mobile phases of Tetranychus urticae and Eotetranychus lewisi on the photosynthetic performance in strawberry (fragaria vesca) with the purpose of determining the mobile phases that most affect photosynthetic performance and determine the chlorophyll and total nitrogen content according to the percentage of infestation. For the present investigation, a completely randomized experimental design with ten treatments and five repetitions was used. In addition, an ADEVA analysis of variance was carried out, subsequently the data were examined using the Tukey test at 5% of the treatments that showed significance. Obtaining positive results regarding the study variables in the case of the variables determination of total chlorophyll in leaves infested by mites and determination of total nitrogen in ug/ was the A2D4 species (Eotetranychus lewisi with a population density of forty mites per plant). Having as averages chlorophyll 39.38 SPAD and total nitrogen 12.36 ug/g. Followed by the variable amount of eggs laid and determination of the mite population that photosynthetically affects the crop, it was found that the A1D4 treatment (Tetranychus urticae with a population density of forty mites per plant) affected the crop in a more photosynthetic way.
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    Determinación de la variabilidad genética de la región ITS2 en poblaciones de Eotetranychus lewisi (MCGREGOR) en el cultivo de Rubus glaucus Bent (mora)
    (2021-09) Sánchez Iza, Emma Cecilia; Santana Mayorga, Rita Cumandá
    Eotetranychus lewisi (Acari: Tetranychidae) is a phytophagous mite able to feed on a wide range of host plant species. Since this mite was recently reported in Ecuador, information on bioecological aspects of the pest is scarce. In this study, the morphological variability evaluated by Principal Component Analysis (PCA) and the genetic variation by genetic distance analysis using the ITS2 region were determined in populations of E. lewisi collected in blackberry plants from different localities from Tungurahua. In this study, blackberry leaves infested with E. lewisi populations were collected from different localities of Tungurahua, Cevallos (C), Quero (Q), Montalvo (M) and Pasa (P), all of these located at different altitude levels. In relation to the genetic study, it was observed that the percentages of the nitrogenous bases in the ITS2 fragment from the different localities show very little variable results. For Adenine, the values coincide with 29.72% for the populations of Cevallos, and 29.91% for Montalvo and Pasa, while the percentage of Cytosine is similar for the four localities (17.06%), likewise there were little variation for Guanine (18.17% for Cevallos; 18.35% for Quero; 18.72% for Montalvo and 18.90% in Pasa. Finally, the percentage of Thymine showed greater variation in Cevallos with 35.05 % with respect to the other populations of Quero (34.86%), Montalvo (34.31%) and Pasa (34.13%). In relation to the nitrogenous bases in the ITS2 fragment there is a greater presence of Thymine followed by Adenine, Guanine and finally Cytosine. On the other hand, the ACP showed that 93.14 and 94.67% of the morphometric variation of E. lewisi in blackberry plants from different locations was explained in 10 components. Of these, the variables that showed greater weight in the first two components were the length of the setae c1, c2, c3, d2, e2, f2 and h3, Sc1, d1, e1, f1 and f2 and in c Regarding the distances between setae, most of the variables were located in the first component (v2- v2, sc1-sc1, c3-c3, d1-d1, d2-d2, e2-e2, f1-f1, h2-h2 and h3-h3).
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    Efecto in vitro del extracto de Clinopodium tomentosum para el control de Eotetranychus lewisi y Oligonychus coffeaee (Acari: Tetranychidae)
    (2020-10) Ortíz Ortíz, Cristian Javier; Vásquez Freytez, Carlos Luis
    The Tetranychidae family contains more than 1,300 species, including more than 100 economically important species due to the economic losses. Oligonychus coffeae and Eotetranychus lewisi were recently registered in Ecuador associated with forest species and different agricultural crops, respectively. Given the importance of the Tetranychidae species in the present study, the in vitro effect of the Clinopodium tomentosum extract was evaluated for the control of Eotetranychus lewisi and Oligonychus coffeae (Acari: Tetranychidae). The effect of different concentrations (0, 1, 2, 4, 8 and 16%) of the ethanolic extract of C. tomentosum on the mortality, oviposition rate and longevity of the females of these mite species was evaluated using the residual contact technique. in rearing units. Mortality evaluations were made 24, 48 and 72 h after application, while oviposition and longevity were determined until female death by sublethal effect. An increase in the mortality rate in females of O. coffeae and E. lewisi was observed as the concentration of the extract of C. tomentosum increased. In O. coffeae, the highest mortality in was reached with concentrations of 8 and 16%, with which 50% mortality was reached, while in E. lewisi, the mortality rate reached 60%. Both in O. coffeae and E. lewisi females, the oviposition rate decreased as the extract concentration increased, mainly from the 4% concentration, which caused a 38.6% decrease in relation to the treatment. control, while with the doses of 8 and 16%, oviposition was reduced by up to 55.6 and 65.8%, respectively. Likewise, a negative relationship between longevity and dose was observed, that is, as the dose of the extract increased, a decrease in longevity was shown in both species of mites, being more noticeable with higher doses (4- 16%) for the case of O. coffeae, while with E. lewisi the reduction was observed with concentrations greater than 2%. Based on the results obtained, the use of the ethanolic extract of C. tomentosum could be included in population management programs for Oligonychus coffeae and Eotetrany
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    Biología y tablas de vida de Eotetranychus lewisi sobre las variedades de durazno Prunus pérsica (zapallo, abridor blanco y tejón)
    (2020-03-19) Miño Pérez, César Ignacio; Vásquez Freytez, Carlos
    Eotetranychus lewisi is an important pest in peach crops in various parts of the world and it has recently been reported in the province of Tungurahua, Ecuador. Therefore, in the present study, the biology and life table of E. lewisi were studied on three peach varieties (‘Zapallo’, Blanco abridor’and ‘Tejón’) under laboratory conditions (). The study was conducted in the Entomology laboratory of the Faculty of Agricultural Sciences, UTA. The mites were collected from Euphorbia pulcherrima. The effect of the variety on the duration of the life cycle of E. lewisi was demonstrated, observing that the lewis mite did not develop when reared on Zapallo leaves, while life cycle was similar in ‘Abridor’ and ‘Tejón’. Regarding the reproductive parameters, Tejon proved to be the breeding substrate that offers the greatest development potential for E. lewisi since it presented less pre-oviposition time and greater fertility, which was evidenced in the parameters of the table of life where it presented the highest data in the net reproduction rate (Ro). Based on the results, cultivar Zapallo seems to have resistance mechanisms to this pest, so its inclusion in a pest management program could be considered.
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    Variación quetotáxica de Tetranychus urticae koch y Eotetranychus lewisi (Mc Gregor) en tres cultivares en la provincia de Tungurahua
    (2019-01) Sánchez Fiallos, Macarena Beatriz; Vásquez Freytez, Carlos
    Species belonging to the family Tetranychidae exhibit a wide phenotypic plasticity in response to environmental variations which could lead to misidentifications due to morphological similarity between some species. In this study, chaetotaxy variations of several Tetranychus urticae and Eotetranychus lewisi populations collected in different host plant species and localities from six municipalities from Province of Tungurahua were evaluated. Strawberry, raspberry and white carrot leaves showing symptoms for tetranychid symptoms were sampled in localities from Ambato, Cevallos, Baños, Mocha, Píllaro and Tisaleo. In the laboratory, each sample was examined under a stereoscopy microscopy magnification to select tetranychid mites as morphotypes. Slides for microscopy observation were prepared using PVA medium and stove dried for 4 days. Species identification was made by comparison of aedeagus morphology. In general, idiosomal setae showed wide variation due to effect of host plant species and locality. Principal Component Analysis (PCA) accounted for 82% of variation observed in measured variables in 19 populations. Measured variables separated populations collected from raspberry leaves, independently from mite species, while populations from white carrot and strawberry were not fairly separated. Chaetotaxy variables showed intra population variation in T. urticae and E. lewisi as effect of host plant species, thus these should be considered for identification in both mite species.