Browsing by Author "Chorbadjian Alonso, Rodrigo Armen"
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- ItemBiogeographical Patterns of Herbivore Arthropods Associated with Chenopodium quinoa Grown along the Latitudinal Gradient of Chile(2021) Chorbadjian Alonso, Rodrigo Armen; Ahumada Becker, María Isabel; Urra, Francisco; Elgueta, Mario; Gilligan, Todd M.Identifying the particular guilds of herbivore arthropods that affect the production of crops is key to developing sustainable pest-management strategies; however, there is incomplete information about the identity of herbivore arthropods that could potentially damage the production of both highland and lowland quinoa landraces grown in Chile. By both reviewing the literature and conducting field collections across a large latitudinal gradient, we generated an updated list of 43 herbivore arthropods associated with quinoa production in Chile. In general, most species are polyphagous feeders, and only seven are specialists. The number and identity of species varied in relation with the latitude, such that four distinctive assemblages of herbivores were identified, each containing 32, 27, 34, and 22 species between latitudes 18-26, 26-32, 32-40, and 40-44 degrees S, respectively. The most northern production area (18-26 degrees S) is affected by nine unique species, including the major quinoa pest Eurysacca quinoae PovolnATIN SMALL LETTER Y WITH ACUTE (Lepidoptera: Gelechiidae). Similarly, the central area (32-40 degrees S) contains four unique species, including Eurysacca media PovolnATIN SMALL LETTER Y WITH ACUTE (Lepidoptera: Gelechiidae) and Orthotylus flavosparsus (Sahlberg) (Hemiptera: Miridae). The particular species assemblages described here will help further development of local pest-management practices.
- ItemClimate change impacts on invasive potential of pink hibiscus mealybug, Maconellicoccus hirsutus (Green), in Chile(2013) Jara Contreras, Valentina Isabel; Meza, Francisco Javier; Zaviezo Palacios, Tania; Chorbadjian Alonso, Rodrigo ArmenMaconellicoccus hirsutus (Green) (Hemiptera: Pseudoccidae) is an important pest in many countries being responsible for considerable economic loses. Although it is not currently present in Chile, the chance that it could be accidentally introduced rises with the list of infested countries increasing over the last years. In addition, climate change projections indicate that a larger region would fit as potential habitat for this pest, allowing it to persist over time and colonize a larger proportion of the Chilean territory. In this study the geographic distribution and the number of generations this mealybug would develop in Chile were determined, under current temperatures and under two projected climatic scenarios. Cumulative degree days were calculated for current and future scenarios using a lower temperature threshold of 14.5 degrees C, with 624.5 degree-days as the thermal requirement for the species to complete one generation. The results show that under current climate conditions M. hirsutus could develop up to three generations in the north of the country (i.e. 18 degrees South) and one generation in the region near 37 degrees South. Under future scenarios' conditions the pest could develop up to five generations in the north, and one generation around the 42 degrees South. Present climate conditions in Chile would allow the establishment of the pink hibiscus mealybug, if the pest enters the country. Climate change conditions would allow the potentially invaded area to expand south, and would promote the development of more generations per year of the mealybug in the studied territory.
- ItemCultivo de cebolla en Chile : claves para una producción sostenible(2016) Contreras E., Samuel; Kelly, E.; Chorbadjian Alonso, Rodrigo Armen; Figueroa Espinoza, Rodrigo; Krarup Hjort, Christian Frederik; Norero, Y.; Rosales V., Marlene
- ItemEfecto de distintas dosis de nitrógeno en la expresión de resistencia de plantas de quinoa (Chenopodium quinoa) frente a insectos defoliadores(2021) Molina Castillo, Jorge Eduardo; Chorbadjian Alonso, Rodrigo Armen; Pontificia Universidad Católica de Chile. Facultad de Agronomía e Ingeniería ForestalLa interacción insecto-planta está determinado por las condiciones abióticas del entorno. Por lo que estudiar el efecto del déficit nutricional en la interacción es una de las formas de abordarlo. El estudio de la expresión de resistencia de la quinoa (Chenopodium quinoa Willd) en situación de déficit nutricional y frente a insectos defoliadores no ha sido ampliamente estudiada. El objetivo general de evaluar el efecto de distintas dosis de nitrógeno en plantas de quinoa y en la expresión de resistencia a insecto defoliador. Las plantas fueron sometidas a tres dosis de nitrógeno (0,1, 0,5 y 1 g N/planta) y se dividieron en tres subgrupos para realizar mediciones de crecimiento y características físico-químicas de las plantas; y del crecimiento y desarrollo de los Noctuidos. Se observó que la quinoa tiene altura y rendimiento menor con dosis baja de nitrógeno. También, plantas defoliadas mecánicamente tuvieron rendimiento de grano similar a mismas dosis aplicadas, presentando capacidad de compensar. Respecto a los aspectos físico-químicas de las hojas, dosis bajas generar un contenido de nitrógeno foliar menor, y una mayor densidad de tricomas, tanto en la cara abaxial como adaxial, y una masa foliar específica mayor. En el crecimiento y desarrollo de insectos, hubo una menor supervivencia, peso de pupa y tasa de crecimiento relativo en insectos que se alimentaron de plantas sometidas a dosis bajas, pero estos consumieron más masa seca total y tuvieron una tasa de consumo relativo. No se encontraron diferencias en el peso máximo larval ni peso del último estado larval.
- ItemEffects of saponin-rich quinoa (Chenopodium quinoa Willd.) bran and bran extract in diets of adapted and non-adapted quinoa pests in laboratory bioassays(Pontificia Universidad Catolica de Chile, Facultad de Agronomia e Ingenieria Forestal, 2019) McCartney, Nathaniel B.; Ahumada, María Isabel; Muñoz, Marcela P.; Rosales Villavicencio, Inés Marlene; Chorbadjian Alonso, Rodrigo Armen; Fierro, Angélica M.© 2019, Pontificia Universidad Catolica de Chile, Facultad de Agronomia e Ingenieria Forestal. All rights reserved.Quinoa (Chenopodium quinoa Willd.) produces bitter-tasting triterpene saponins that must be removed prior to consumption, significantly adding to production costs. Breeders have therefore prioritized the development of low-saponin “sweet” cultivars with little concern for the ecological benefits these compounds may confer. Quinoa saponins are thought to provide protection against herbivores and microbial pathogens, although there is very little data to support these assumptions. Here we begin to address the question of whether biologically relevant concentrations of saponins exert negative effects against insects and pathogens that attack quinoa, as well as against species not associated with quinoa. Using bran of the coastal genotype Cáhuil as the source of saponins, we conducted feeding assays with larvae of 3 noctuid insect species. Antifungal activity against 8 species was assayed using bran extract incorporated into PDA media. Quinoa bran showed insecticidal activity against only the non-quinoa feeder Pseudaletia impuncta, while the quinoa feeders Trichoplusia ni and Feltia subterranea were not affected. The bran extract inhibited fungal colony growth of Alternaria arborescens, Botrytis cinerea, and Phytophthora cinnamomi by approximately 50% but had less growth inhibitory effect on Fusarium oxysporum f. sp. cepae, Pestalotiopsis clavispora, Penicillium digitatum, Geotrichum sp., and the quinoa pathogen Phoma sp. The relatively higher inhibitory activity against some pathogen species did not necessarily correlate with their expected pathogenicity against quinoa. The results of this study suggest that, while the quinoa saponins present in bran and bran extracts may provide some protection against certain insects and phytopathogens, species-specific responses need further exploration.
- ItemEstudios de dormancia y germinación de malva (Malva parviflora) = Dormancy and germination studies on mallow (Malva parviflora).(2004) Chorbadjian Alonso, Rodrigo Armen
- ItemEvaluación del efecto repelente del salvado de quínoa rico en saponina (Chenopodium quinoa) sobre Bagrada hilaris y Brevicoryne brassicae en plantas de Brassica oleracea(2022) Toledo Bórquez, Sebastián Alejandro; Chorbadjian Alonso, Rodrigo Armen; Pontificia Universidad Católica de Chile. Facultad de Agronomía e Ingeniería ForestalActualmente, debido al riesgo que implica el uso de insecticidas sintéticos, es menester la creación de productos naturales que sean más amigables con el ecosistema. El objetivo de esta investigación fue evaluar el efecto repelente del salvado de quínoa rico en saponina (Chenopodium quinoa Willd.) sobre el chinche pintado (Bagrada hilaris) y el pulgón del repollo (Brevicoryne brassicae) en repollo, brócoli y kale. Para el ensayo en chinches, cada hoja fue dividida en dos áreas, dejando un área tratada con salvado de quínoa (1, 10 y 30 g·L⁻¹) y un área no tratada. Se contabilizó el número de chinches durante aproximadamente un día, y posteriormente se calculó la superficie dañada, analizando ambos datos mediante un índice de preferencia. No hubo diferencias significativas en el número de chinches en ninguna variedad (p > 0,05), mientras que en el caso de la superficie dañada solo kale presentó diferencias significativas (p = 0,019). Por otro lado, para el ensayo en pulgones, las plantas fueron sometidas a tratamientos con y sin la aplicación de salvado (30 g·L⁻¹). Las plantas se dejaron infestar naturalmente durante una semana y se contabilizó el número de pulgones por planta. No hubo diferencias significativas en ningún tratamiento (p > 0,05). En el caso del chinche pintado, se observó en ambos tipos de parámetros un efecto de repelencia en todas las variedades y concentraciones utilizadas. Por el contrario, en el caso del pulgón del repollo no se observó efecto de repelencia en ninguna de las variedades.
- ItemPectin Methylesterases Modulate Plant Homogalacturonan Status in Defenses against the Aphid Myzus persicae(2019) Silva-Sanzana, C.; Celiz-Balboa, J.; Garzo, E.; Marcus, S.E.; Parra-Rojas, J.P.; Rojas, B.; Olmedo, P.; Rubilar, M.A.; Rios, I.; Chorbadjian Alonso, Rodrigo Armen; Fereres, A.; Knox, P.; Saez-Aguayoa, S.; Blanco-Herrera, F.