Artículos científicos

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Adsorption and desorption variability of four herbicides used in paddy rice production
(2011-01) Alister, Claudio A.; Araya, Manuel A.; Kogan, Marcelo
This investigation was performed to determine the effect of physicochemical soil properties on penoxsulam, molinate, bentazon, and MCPA adsorption-desorption processes. Four soils from Melozal (35° 43' S; 71° 41' W), Parral (36° 08' S; 71° 52' W), San Carlos (36° 24' S; 71° 57' W), and Panimavida (35° 44' S; 71° 24' W) were utilized. Herbicide adsorption reached equilibrium after 4 h in all soils. The Freundlich L-type isotherm described the adsorption process, which showed a high affinity between herbicides and sorption sites mainly because of hydrophobic and H-bonds interaction. Penoxsulam showed the highest adsorption coefficients (4.23 ± 0.72 to 10.69 ± 1.58 mL g⁻¹) and were related to soil pH. Molinate showed K(d) values between 1.72 ± 0.01 and 2.3 ± 0.01 mL g⁻¹ and were related to soil pH and organic matter, specifically to the amount of humic substances. Bentazon had a high relationship with pH and humic substances and its K(d) values were the lowest, ranging from 0.11 ± 0.01 to 0.42 ± 0.01 mL g⁻¹. MCPA K(d) ranged from 0.14 ± 0.02 to 2.72 ± 0.01 mL g⁻¹, however its adsorption was related to humic acids and clay content. According to these results, the soil factors that could explain the sorption process of the studied herbicides under paddy rice soil conditions, were principally humic substances and soil pH. Considering the sorption variability observed in this study and the potential risk for groundwater contamination, it is necessary to develop weed rice management strategies that limit use of herbicides that exhibit low soil adsorption in areas with predisposing conditions to soil leaching.
An Assessment of the Feasibility of Phytoextraction for the Stripping of Bioavailable Metals from Contaminated Soils
(2022-12-29) Santa‐Cruz, Javier; Robinson, Brett; Krutyakov, Yurii A.; Shapoval, Olga A.; Peñaloza, Patricia; Yáñez, Carolina; Neaman, Alexander
Phytoextraction has been proposed in many papers as a low-cost method for remediating contaminated soil. However, if national regulation is based on total metal(loid) concentrations in soil, phytoextraction is generally infeasible because of the long time required for remediation. Assessing phytoextraction requires determination of the dynamic rate of metal removal from soil. Phytoextraction may be feasible if the main goal is to reduce the soluble fraction of the metal(loid) with the goal of reducing bioavailability. However, it has been reported that there is a large mass balance mismatch between the reduction of the soluble metal fraction in contaminated soil and metal uptake by plants. Several studies report that the decrease of soluble fraction of metals in soil is higher than can be accounted for by plant uptake. In other words, studies generally overestimate the feasibility of bioavailable contaminant stripping. Therefore, a more rigorous approach is advisable to ensure that papers on bioavailable contaminant stripping include relevant information on mass balances. Furthermore, to implement the concept of bioavailable contaminant stripping, regulations must distinguish between the bioavailable fraction and the total metal concentration in soil.
Aproximaciones a la deserción universitaria en Chile
(2018) Arancibia Carvajal, Rosa; Trigueros Cervantes, Carmen
La educación universitaria vespertina, en Chile, ha presentado en los últimos años, un acentuado crecimiento en su matrícula. Sin embargo, la interrupción de los estudios de quienes estudian en este horario de 19 a 23 horas (vespertino) ha sobrepasado la cifra promedio de deserción del sistema universitario chileno. Estos estudiantes se caracterizan por combinar responsabilidades familiares, laborales y académicas, presentando mayores niveles de deserción que los estudiantes que ingresan a la modalidad universitaria diurna, debido a las particularidades y situaciones que les rodean. En este contexto, esta investigación se propuso indagar sobre los factores que intervienen en las decisiones de abandono de los estudiantes universitarios con características no tradicionales, que asisten a programas de estudios vespertinos. Metodológicamente se optó por un diseño de investigación cualitativo de tipo exploratorio debido a la escasa investigación en la temática en el país. Para ello, se realizaron entrevistas semiestructuradas a diez estudiantes desertores vespertinos. Una vez sistematizada la información, se obtuvo cuatro dimensiones emergentes de análisis, que sintetizaron las lógicas y significados que intervienen en el fenómeno que afecta a este grupo específico. Los hallazgos sobre la decisión de abandono de los estudiantes vespertinos de características no tradicionales dan cuenta de los siguientes factores, según relevancia, condiciones y características personales, capital y desempeño académico, imprevistos y circunstancias adversas y experiencias con la oferta institucional.
Bartonella Infection in Stray Dogs from Central and Southern Chile (Linares and Puerto Montt)
(Vector-Borne and Zoonotic Diseases, 2020) Weinborn-Astudillo, Romy M.; Pau, Natalia; Tobar, Bret Z.; Jaffe, David A.; Boulouis, Henri-Jean; Sepúlveda, Paulina; Müller, Ananda; Chomel, Bruno B.
Bartonellae are emerging zoonotic vector-borne pathogens causing a broad spectrum of clinical symptoms in humans and animals, including life-threatening endocarditis. Dogs are infected with a wide range of Bartonella species and infection has been reported in free-roaming dogs from various South American countries. We report a high Bartonella seroprevalence in 82 Chilean stray dogs. More than half of the dogs from Linares (72.7%, n = 66) and Puerto Montt (56.2%, n = 16) were seropositive for Bartonella henselae, Bartonella vinsonii ssp. berkhoffii, or Bartonella clarridgeiae with antibody titers ranging from 1:64 to 1:512. Three dogs (3.6%) were PCR positive for Bartonella sp. Partial sequencing of the gltA gene indicated that two dogs were infected with B. henselae, and one with a strain close to Bartonella vinsonii ssp. vinsonii. Exposure to Bartonella species was common in stray Chilean dogs, as for other South American countries, likely associated with heavy ectoparasite infestation.
Blood-Meal Sources and Trypanosoma cruzi Infection in Coastal and Insular Triatomine Bugs from the Atacama Desert of Chile
(2022-04-08) Quiroga, Nicol; Correa, Juana P.; Campos-Soto, Ricardo; San Juan, Esteban; Araya-Donoso, Raúl; Díaz-Campusano, Gabriel; González, Christian R.; Botto-Mahan, Carezza
Mepraia parapatrica is one of the lesser known and less abundant sylvatic triatomine species naturally infected by the protozoan Trypanosoma cruzi, the etiological agent of Chagas disease. M. parapatrica lives in sympatry with T. cruzi-infected rodents, but only birds, reptiles, and marine mammals have been reported as blood-meal sources of this vector species by serology. The distribution range of this kissing bug overlaps with fishers’ settlements and tourist areas, and therefore the study of the blood-meal sources of this triatomine species is relevant. Here, we determined the blood-meal sources of M. parapatrica by NGS or standard sequencing from a coastal mainland area and an island in northern Chile, and T. cruzi infection by real-time PCR. The blood-meals of. M parapatrica included 61.3% reptiles, 35.5% mammals (including humans) and 3.2% birds. Feeding on reptiles was more frequent on the mainland, while on the island feeding on mammals was more frequent. The presence of T. cruzi-infected triatomine bugs and humans as part of the diet of M. parapatrica in both areas represents an epidemiological threat and potential risk to the human population visiting or established in these areas. Currently there are no tools to control wild triatomines; these results highlight the potential risk of inhabiting these areas and the necessity of developing information campaigns for the community and surveillance actions.
Brucelosis en personas con riesgo ocupacional en clínicas veterinarias de dos ciudades del centro sur de Chile
(2020-11-25) Weinborn A., Romy; Zanelli G., Macarena; Troncoso T., Ignacio; Opazo V., Álvaro; Valenzuela A., Karina; Cárdenas Z., Sebastián; García, Rodrigo; Vásquez A., Samuel
El objetivo del estudio fue determinar la seroprevalencia de Brucella spp en personas con riesgo ocupacional en clínicas veterinarias de dos ciudades del centro sur de Chile (Talca y Puerto Montt). Se analizaron 98 sueros humanos mediante la técnica de aglutinación Wright-Huddleson (sensibilidad 54.9%, especificidad 100%) y se utilizó el test exacto de Fischer o X2 para evaluar diferencias significativas entre grupos (p<0.05). Se encontró 3% de seropositividad a Brucella spp (1.8% [1/53] para Talca y 4.4% [2/45] para Puerto Montt). Según las funciones realizadas dentro de las clínicas veterinarias, la seropositividad fue de 1.4% (1/71) para alumnos de medicina veterinaria y 10% (2/19) en médicos veterinarios, sin diferencias significativas entre grupos.
Burnout syndrome prevalence in veterinarians working in Chile
(2019) Weinborn, Romy M.; Bruna, Braulio J.; Calventus, Joan; Sepúlveda, Gerardo A.
Burnout Syndrome is a psycho-emotional syndrome that affects workers in any activity or profession. In recent years, veterinarians have been described as one of the most affected professionals, which has motivated the development of this research. The primary objective of this work was to determine the prevalence of Burnout Syndrome in veterinarians working in Chile. We evaluated the possible correlation of Burnout Syndrome with socio-demographic variables. The Socio-Demographic Characterization Survey and the Maslach Burnout Syndrome Inventory-General Survey (MBI) were applied to 521 participants, who were contacted through the Veterinary Medical Association of Chile (COLMEVET) and social networks. Fisher and Chi-square statistical tests and correspondence analysis were used to determine the association among variables. The prevalence of Burnout Syndrome in Chilean veterinarians was 24% (124/521). There was statistical significance between Burnout Syndrome and the variables ‘years in employment’ and ‘monthly salary’. There is a high prevalence of Burnout Syndrome in veterinarians working in Chile that was related to the variables ‘years in employment’ and ‘monthly salary’. Prevention using psychological therapy could reduce the incidence of symptoms linked to adaptive difficulties, cognitive discrepancies, psychological discomfort, and emotional regulation, promoting health improvement and resistance to Burnout Syndrome in Chilean veterinarians. This research corresponds to the first exploratory study related to the subject in Chile.
Caracterización y evolución temporal de la mortalidad por zoonosis bajo declaración obligatoria, entre los años 1997 y 2018
(2021-07-30) Reyes, Rodolfo; Yohannessen, Karla; Cuadros, Natalia
Introducción: Las zoonosis son enfermedades transmitidas desde un hospedador animal al ser humano o viceversa. En Chile, las zoonosis de Notificación Obligatoria (NO) son: brucelosis, carbunco, triquinosis, hidatidosis, leptospirosis, dengue, enfermedad de Chagas, hantavirosis y rabia. Objetivo: Evaluar la tendencia y caracterizar la mortalidad por zoonosis de NO en Chile entre 1997-2018. Metodología: Estudio ecológico de la mortalidad por zoonosis de NO. Se utilizaron bases de mortalidad y población oficiales. Se describió la mortalidad relativa, general y específica, según variables sociodemográficas. Se calcularon tasas de mortalidad anuales brutas (TMb) y ajustadas (TMa, método directo). Se evaluó la tendencia temporal con modelos de regresión de Prais-Winsten. Resultados: Entre 1997 y 2018 la mortalidad por zoonosis de NO correspondió al 0,12% (2.359 muertes) de la mortalidad total, siendo las principales causas la enfermedad de Chagas (59,8%), hidatidosis (23,9%) y hantavirosis (13,8%). La TMa general disminuyó significativamente (B: -0,017; IC95%: -0,024; -0,009) al igual que hidatidosis (B: -0,011; IC95%: -0,013; -0,008), sólo hantavirosis mostró un aumento (no significativo). Conclusión: La mortalidad por zoonosis de NO disminuyó durante el período estudiado; solo la hantavirosis mostró un aumento en su tendencia. Se sugiere enfocar estrategias para prevenir la transmisibilidad y mortalidad por hanta, así como mejorar el acceso a tratamiento para las otras zoonosis.
Changes in Dynamic Thiol/Disulfide Homeostasis, and Substance P, B-Endorphin and α-Tocopherol Concentrations in the Spinal Cord of Chronically Lame Dairy Cows
(2023-05-12) Müller, Heine; Herzberg, Daniel; Chihuailaf, Ricardo; Strobel, Pablo; Werner, Marianne; Bustamante, Hedie
Initial lameness inflammation leads to chronic lameness and development of chronic pain due to the release of pro-inflammatory mediators such as reactive oxygen species (ROS), which are implicated in the transition from acute to chronic pain, and free radical scavengers countering thiol, substance P (SP), and β-endorphin (BE). The present study aimed to evaluate the dynamic thiol–disulfide homeostasis, α-tocopherol concentrations and SP and BE concentrations in the spinal cord of chronically lame dairy cows. Ten lame and 10 non-lame cows with a parity range of 2–6 were selected for the study. Lame cows had a history of up to 3 months of lameness. Spinal cord samples were obtained from the L2 to L4 lumbar vertebrae aspect of each animal. A thiol–disulfide homeostasis assay was performed using absorbance, and the α-tocopherol concentration was determined by HPLC. SP and BE concentrations were measured using ELISA kits. The results indicated that SP and BE were significantly higher in the spinal cord of lame cows. In contrast, disulfide levels and α-tocopherol concentrations were significantly lower in the spinal cord of lame cows. In conclusion, disulfide levels and α-tocopherol concentrations indicated a defective antioxidant response in cows with chronic lameness. The results of SP and BE concentrations suggested chronic pain and a defective endogenous analgesic response.
Chilean regulations on metal-polluted soils: The need to advance fromadapting foreign laws towards developing sovereign legislation
(Environmental Research, 2020) Neaman, Alexander; Valenzuela, Patricio; Tapia-Gatica, Jaime; Selles, Iván; Novoselov, Alexey A.; Elvira A. Dovletyarova; Yáñez, Carolina; Krutyakov, Yurii A.; Stuckey, Jason W.
Chile as a major international Cu producer faces serious soil contamination issues in mining areas. CurrentlyChile does not have any specific law governing the maximum permissible concentrations of metals in soils toprotect ecosystems and human health. Chile heavily relies on the use of environmental laws of 14 foreigncountries; the choice of the country depends on the similarity of its environmental conditions with those in Chile.In this study, we used an online database to compare the similarity of Chilean rocks to those in foreign countries.Likewise, we performed soil sampling and determined the background concentrations of Cu, As, Pb, and Zn insoils of the Aconcagua basin, the largest river basin in the Valparaiso Region of central Chile. The results showedthat geochemical patterns in Chile have the greatest resemblance to New Zealand, Mexico, and Italy. Thebackground Cu concentration in the Aconcagua basin (134 mg kg−1) exceeded the legislated limits of NewZealand (100 mg kg−1) and Italy (120 mg kg−1), whereas the background Zn concentration (200 mg kg−1)exceeded the legislated limit of Italy (150 mg kg−1). Due to the elevated natural abundance of Cu and Zn inChile, international laws should not be applied in Chile for the assessment of soil contamination. In addition, weassessed ecological risk using the results of our previous studies obtained by analyzing nativefield-contaminatedsoils of the Valparaiso region. In the Aconcagua basin, Cu posed high risk for plants in 11% of the samples,whereas As posed high risk for earthworms in 48% of the samples. We suggest that future studies are required tosearch for other organisms that can serve as biomarkers of metal toxicity because our previous studies werelimited to plants and earthworms. Importantly, As posed high risk to human health in 25% of the samples in ourstudy. There is a need for future studies to demonstrate empirically an association between soil As and children'sblood As in order to establish the national threshold values of soil As to protect human health. We conclude thatthere is an urgent need in Chile to advance from the current approach of adapting foreign laws to developingChilean sovereign environmental legislation.
Clinical presentation and treatment of multifocal epitrichial sweat gland carcinoma in a horse
(2020) Dörner, Cristóbal A.; Castellón, Cristóbal H.; Yañez, Diego
Epitrichial gland carcinoma is a very rare type of skin tumour in horses. This report describes a horse presenting multiple nodules with associated normal, alopecic and ulcerated skin diagnosed via histopathology as epitrichial gland carcinoma. Treatment consisted of combined surgical excision, topical therapy for ulcerated nodules and cryotherapy for non-ulcerated tumours. Six months following therapy, the excised masses had not regrown and only 10 out of 25 small tumours previously treated with cryotherapy were noticeable.
Competitive Strategies and Growth of Neighbouring Bromus valdivianus Phil. and Lolium perenne L. Plants Under Water Restriction
(2013-05) López, F.; Kemp, P. D.; Dörner, J.; Descalzi, C. A.; Balocchi, O. A.; García, S.
Often perennial pastures have to tolerate soil water restriction during summer, which can affect the relative abundance of the most desired species. In the south of Chile, Bromus valdivianus and Lolium perenne are preferred species. The competitiveness of B. valdivianus and L. perenne was evaluated when sown in pots in a glasshouse as monocultures or a mix (50/50 %) with restricted water availability. The water restriction treatments were as follows: 80–85 % field capacity (FC), 45–50 % FC and 20–25 % FC, maintained for 1196 growing degree days. For both species, dry matter (DM) accumulated per plant and per pot decreased similarly with increasing water restriction, but at tiller level, resource allocation differed, for B. valdivianus root growth was accentuated over aerial development, but this was less so for L. perenne. The foliage mass per tiller for B. valdivianus decreased relatively more than that for L. perenne with increasing water restriction. As monocultures, B. valdivianus produced larger tillers than L. perenne, such that B. valdivianus tillers had 2.2 times greater lamina mass, 3.6 times more leaf area and 2.5 times greater root mass than those of L. perenne. However, L. perenne produced a larger number of smaller tillers that enabled foliage, root and total mass at plant level, to be similar to that of B. valdivianus. Within the mixed pasture, L. perenne tiller density increased compared with when grown as a monoculture, but not for B. valdivianus. The results of the study suggested that L. perenne and B. valdivianus have differences in growth strategies that allow them to survive under environmental stress and competition. Competitiveness increased for L. perenne aboveground without water restriction and that for B. valdivianus increased belowground as water restriction was increased.
Corticotropin-releasing factor system in the lateral septum: Implications in the pathophysiology of obesity
(2022-09-20) Olivares-Barraza, Rossy; Marcos, José Luis; Martínez-Pinto, Jonathan; Fuenzalida, Marco; Bravo, Javier A.; Gysling, Katia; Sotomayor-Zárate, Ramón
Obesity is a pandemic associated with lifestyles changes. These include excess intake of obesogenic foods and decreased physical activity. Brain areas, like the lateral hypothalamus (LH), ventral tegmental area (VTA), and nucleus accumbens (NAcc) have been linked in both homeostatic and hedonic control of feeding in experimental models of diet-induced obesity. Interestingly, these control systems are regulated by the lateral septum (LS), a relay of γ-aminobutyric (GABA) acid neurons (GABAergic neurons) that inhibit the LH and GABAergic interneurons of the VTA. Furthermore, the LS has a diverse receptor population for neurotransmitters and neuropeptides such as dopamine, glutamate, GABA and corticotropin-releasing factor (CRF), among others. Particularly, CRF a key player in the stress response, has been related to the development of overweight and obesity. Moreover, evidence shows that LS neurons neurophysiologically regulate reward and stress, although there is little evidence of LS taking part in homeostatic and hedonic feeding. In this review, we discuss the evidence that supports the role of LS and CRF on feeding, and how alterations in this system contribute to weight gain obesity.
Corticotropin-releasing factor system in the lateral septum: Implications in the pathophysiology of obesity
(2022-09-20) Olivares-Barraza, Rossy; Marcos, José Luis; Martínez-Pinto, Jonathan; Fuenzalida, Marco; Bravo, Javier A.; Gysling, Katia; Sotomayor-Zárate, Ramón
Obesity is a pandemic associated with lifestyles changes. These include excess intake of obesogenic foods and decreased physical activity. Brain areas, like the lateral hypothalamus (LH), ventral tegmental area (VTA), and nucleus accumbens (NAcc) have been linked in both homeostatic and hedonic control of feeding in experimental models of diet-induced obesity. Interestingly, these control systems are regulated by the lateral septum (LS), a relay of γ-aminobutyric (GABA) acid neurons (GABAergic neurons) that inhibit the LH and GABAergic interneurons of the VTA. Furthermore, the LS has a diverse receptor population for neurotransmitters and neuropeptides such as dopamine, glutamate, GABA and corticotropin-releasing factor (CRF), among others. Particularly, CRF a key player in the stress response, has been related to the development of overweight and obesity. Moreover, evidence shows that LS neurons neurophysiologically regulate reward and stress, although there is little evidence of LS taking part in homeostatic and hedonic feeding. In this review, we discuss the evidence that supports the role of LS and CRF on feeding, and how alterations in this system contribute to weight gain obesity.
Daily changes on seasonal ecophysiological responses of the intertidal brown macroalga Lessonia spicata: Implications of climate change
(2022-09-28) Celis-Pla, Paula S. M.; Trabal, Andres; Navarrete, Camilo; Troncoso, Macarena; Moenne, Fabiola; Zuñiga, Antonio; Figueroa, Felix L.; Saéz, Claudio A.
Global climate change is expected to have detrimental effects on coastal ecosystems, with impacts observable at the local and regional levels, depending on factors such as light, temperature, and nutrients. Shifts in dominance between primary producers that can capitalize on carbon availability for photosynthesis will have knock-on effects on marine ecosystems, affecting their ecophysiological responses and biological processes. Here, we study the ecophysiological vulnerability, photoacclimation capacity, and tolerance responses as ecophysiological responses of the intertidal kelp Lessonia spicata (Phaeophyceae, Laminariales) during a year through different seasons (autumn, winter, spring, and summer) in the Pacific Ocean (central Chile). Six different daily cycle experiments were carried out within each season. A battery of different biochemical assays associated with antioxidant responses and in-vivo chlorophyll a fluorescence parameter showed that during spring and summer, there was an increase in photosynthetic capacity in the macroalgae, although their responses varied depending on light and nutrient availability in the course of the year. Lessonia spicata showed maximal photosynthesis and a similar photoinhibition pattern in summer compared to the other seasons, and the contents of nitrate and phosphorous in seawater were less in winter. Thus, high irradiance during spring and summer displayed a higher maximal electron transport rate (ETRmax), irradiance of saturation (Ek), non-photochemical quenching (NPQmax), nitrogen and carbon contents, and photoprotector compound levels. Antioxidant activity increased also in summer, the seasonal period with the highest oxidative stress conditions, i.e., the highest level of hydrogen peroxide (H2O2). In contrast, under low irradiance, i.e., wintertime conditions, L. spicata demonstrated lower concentrations of the photosynthetic pigments such as chlorophyll a and carotenoids. Our study suggests that macroalgae that are subjected to increased irradiance and water temperature under lower nutrient availability mediated by seasonal changes (expected to worsen under climate change) respond with higher values of productivity, pigment contents, and photoprotective compounds. Thus, our findings strengthen the available evidence to predict that algae in the order Laminariales, specifically L. spicata (kelp), could better proliferate, with lower vulnerability and greater acclimation, than other marine species subject to future expected conditions associated with climate change.
Dendrobium nobile in vitro flowering induction
(2023-05-22) Nadal, Michele Carla; Silva Andrade, Gracielle Vidal; Nunes Flores, José Henrique; dos Reis, Michele Valquíria; Rodrigues, Vantuil Antonio; Pasqual, Moacir
In vitro flowering is a technique used in genetic improvement that accelerates generations and favors the faster fixation of new traits of agronomic and market interest. The study aimed to establish a protocol for the in vitro flowering of Dendrobium nobile, through the combined temperature and of the growth regulator thidiazuron (TDZ) effects. Experiments was performed in a flask that was kept in a BOD incubator at 18, 21, or 24 °C or in a growth room at 26 °C. The TDZ concentrations were 0.0, 0.5, 1.0, and 2.0 mg L-1. The highest percentage of flowering shoots of 13.7% occurred at a concentration of 2 mg L-1 of TDZ grown at a temperature of 18 °C. Dendrobium nobile in vitro flowering was promoted in plants cultivated in ½ MS supplemented with 30 g L-1 sucrose, 5.5 g L-1 agar, 100 mL L-1 coconut water, pH 6.0, and 2.0 mg L-1 TDZ at a controlled temperature of 18 °C and a photoperiod of 16 h. The in vitro flowering induction protocol of the D. nobile species could be used or improved for future studies.Keywords: flowering, temperature, thidiazuron, Orchidaceae.
DETECCIÓN DE Trypanosoma cruzi EN LAGARTOS Microlophus atacamensis DE UNA ISLA COSTERA DEL DESIERTO DE ATACAMA
(2024-06) Borcosque. Josefa; Campos-Soto, Ricardo; Quiroga, Nicol; Cianferoni, Franco; Díaz-Campusano, Gabriel; Marcos, José Luis; Botto-Mahan, Carezza; Torres-Pérez, Fernando
La enfermedad de Chagas es producida por el parásito Trypanosoma cruzi, el cual está presente en vinchucas y sangre/tejidos de mamíferos, considerándose las aves refractarias a la infección. Mepraia es un género de vinchuca responsable de transmitir T. cruzi en el ciclo silvestre de Chile. Se ha evidenciado la presencia de ejemplares de Mepraia infectados con T. cruzi en la Isla Santa María (Región de Antofagasta). En esta isla no se ha registrado presencia de micromamíferos y los vertebrados más comunes son el lagarto Microlophus atacamensis, jotes y aves marinas. En las vinchucas de esta isla se ha reportado un alto porcentaje de infección e incluso infecciones mixtas, con más de un DTU de T. cruzi, lo que está comúnmente asociado a ecosistemas con una alta biodiversidad y abundancia de mamíferos. Esto contrasta con la nula captura de micromamíferos reportada en esta isla. Considerando que recientemente se ha publicado que los reptiles también son hospederos de T. cruzi, se puede inferir que los lagartos M. atacamensis podrían estar manteniendo la infección de T. cruzi en la Isla Santa María. El objetivo de este estudio es determinar si individuos de M. atacamensis de la Isla Santa María son hospederos de T. cruzi. En 33 muestras de sangre de M. atacamensis se detectó T. cruzi mediante la amplificación de un segmento de ADN kinetoplastídico por PCR convencional y un segmento nuclear de T. cruzi por real time PCR. Se determinó un 60.6% de infección mediante PCR convencional, mientras que por real time PCR un 51.1%. Se concluye que M. atacamensis es un hospedero de T. cruzi, sugiriendo que podría ser un reservorio clave que está mantenido la infección en la Isla Santa María. Estos resultados contribuyen al entendimiento del ciclo de vida que desarrolla T. cruzi en esta particular isla del extremo norte del desierto de Atacama.
Determinación del Efecto de Tres Concetraciones de Aceite Esencial de Eucalipto, para el Control Ecológico de la Varroasis en Colmenas en Producción, en Los Molles, Región de Valparaíso, Chile
(2018) Ahumada, M.; Marcos, José L.; Bañares, G.
La varroasis es producida por ácaros de la especie Varroa destructor, un ectoparásito que desde hace décadas, ha generado graves problemas a la producción apícola nacional y mundial. El año 1992 se diagnosticó por primera vez en Chile, con carácter de emergencia sanitaria (FIA, 2009). Existen distintas opciones terapéuticas químicas alopáticas para su control, como por ejemplo flumetrina, fluvalinato, amitraz, etc., pero desencadenan efectos tóxicos sobre el sistema nervioso de las abejas, reduciendo el rendimiento de aprendizaje en los insectos (Tan et al., 2013). También el uso y abuso de estos acaricidas ha generado resistencia de Varroa a dichos productos (Moreno, 2006). Los productos alternativos más interesantes son los aceites esenciales de timol y eucalipto, y los ácidos orgánicos oxálico y fórmico (Jaume, 2003). Según Principal et al. (2004), el aceite esencial de eucalipto es efectivo en reducir la población de Varroa, y su acción fue más evidente a las 36 h post tratamiento. La actividad insecticida del aceite esencial de eucalipto ha sido descrita como agonista del receptor de octopamina (Rattan, 2010). Los aceites esenciales de plantas presentan una buena eficacia en el control de Varroa, una mínima residualidad en la miel y no dañan a las abejas (Schmidt et al., 2008). El objetivo de este trabajo fue determinar los efectos de tres concentraciones del aceite esencial de eucalipto como tratamiento ecológico contra la varroasis en colmenas en producción.
Efectos de Aceites Esenciales de Lavanda y Eucalipto en el Control de la Varroasis de Apis melifera
(2018) Marcos, J.; Ahumada, M.; Cadavid, A.; Bañares, G.; Silva, C.
Las abejas como polinizadores participan en la economía global y su aporte ha sido estimado entre 235 y 285 billones de US$ al año. (Lautenbach, et al., 2012) Actualmente se ha informado el debilitamiento general de las abejas melíferas, representado por pérdidas de colonias, elevando la preocupación pública, encareciendo el manejo de las colonias de abejas y aumentando los costos de los servicios de polinización (Calderone, 2012). El ácaro Varroa destructor se considera un impulsor crucial de esta difícil situación mundial de colonias de de abejas (Le Conte, et al., 2010). Los métodos actuales utilizados para controlarlo, son la aplicación de acaricidas piretroides (fluvalinate) y organofosforados (coumaphos) que inicialmente fueron altamente efectivos, pero el uso frecuente de estos ha llevado al desarrollo de la resistencia de los ácaros (Milani, 1999). Los aceites esenciales (AE) ofrecen una alternativa generalmente más barata y segura para el hombre y las abejas (Isman 2000). Son clasificados como suplementos alimenticios y seguros para consumo humano (Quarles, 1996). Los AE, pueden alterar el comportamiento, el crecimiento y desarrollo, la ecdisis, el apareamiento y la oviposición de los insectos (Khater, 2011). La actividad insecticida de los componentes de los AE de lavanda y eucalipto ha sido relacionada con la inhibición de la acetilcolinesterasa y como agonista octopaminergico respectivamente. (Rattan, 2010). El AE de eucaliptus es efectivo en reducir la población de varroa, (Principal, et al., 2004) El objetivo fue determinar el efecto de los AE de lavanda y eucalipto para el control de la varroasis en condiciones de campo.
Effects of physicochemical soil properties of five agricultural soils on herbicide soil adsorption and leaching
(2011) Alister, Claudio; Araya, Manuel; Kogan, Marcelo
Once pesticides reach the soil, there are several factors that affect their soil behavior. To identify the principal soil and herbicide properties that control their adsorption and leaching, a study of five Chilean agricultural and forest soils was performed. Simazine, diuron, terbuthylazine and MCPA were applied to the top of 45-cm tall by 12-cm diameter disturbed soil columns, filled with either an Andisol, Ultisol, Entisol or one of two Inceptisol soils. After herbicide applications, each lysimeter received 24 mm of simulated rain every 24 hours for five days. Once water percolation stopped, the lysimeters were divided into five sections and herbicide concentrations were quantified using High Pressure Liquid Chromatography. Relationships between soil physicochemical properties, herbicide sorption (adsorption and desorption) and herbicide leaching were determined. All herbicides exhibited the least depth reached from the Andisol soil (10 cm) and the highest from the Ultisol soil (45 cm). The principal soil property that affected herbicide adsorption was the soil organic carbon content, specifically the fulvic acid-humins fraction. Soil leaching was related to the inverse of soil adsorption (1/Kd), cation exchange capacity, humic substances content and herbicide pKa. These results suggest that it is possible to develop simple quantitative models to predict the soil-leaching properties of pesticides.

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