Scielo RSS <![CDATA[Idesia (Arica)]]> http://www.scielo.cl/rss.php?pid=0718-342920120001&lang=en vol. 30 num. 1 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[<i>Technologies of soilless culture and their sustainability</i>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100001&lng=en&nrm=iso&tlng=en <![CDATA[<i>Carbon sequestration potential in agricultural soils under organic management to reduce greenhouse effect gas emissions</i>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100002&lng=en&nrm=iso&tlng=en O aumento da concentração dos gases de efeito estufa na atmosfera poderá ter conseqüências graves para toda sociedade. O desflorestamento e o uso dos solos para a produção de alimentos têm contribuído significativamente para aumentar a emissão desses gases. Com o objetivo de monitorar o teor de matéria orgânica e contabilizar o estoque de carbono de diversas unidades de solos, em área experimental de agricultura orgânica no estado do Espírito Santo, Brasil, foi realizado um estudo, caracterizando anualmente 12 unidades de solo, no período de 1990 a 2000. Observou-se acréscimo nos teores de matéria orgânica e de carbono do sistema. Na camada de 0 a 40 cm de profundidade, o estoque de carbono elevou-se de 34,57 t ha-1 para 58,19 t ha-1, com fixação de 23,62 t ha-1 em 10 anos, o que corresponde a 86,62 t ha-1 de CO2. Conclui-se que o manejo agroecológico em sistema orgânico de produção permite elevar o teor de matéria orgânica dos solos, pela reciclagem e seqüestro de carbono atmosférico, confirmando elevado potencial para reduzir as emissões de Gases de Efeito Estufa, podendo contribuir para a redução do aquecimento global.<hr/>The increase in the concentration of greenhouse gases in the atmosphere will have serious consequences for all of society. Deforestation and the use of soils for production of food have contributed significantly to increase the emission of greenhouse gases. With objectives to monitor the levels of organic matter and quantify the carbon content of diverse soil units in an organic agriculture research area in the State of Espírito Santo, Brazil, a study was carried out characterizing annually 12 units of soil, during the period of 1990 to 2000. An increase in the levels of organic matter and carbon in the system was observed. In the soil layer from 0 to 40 cm deep, the carbon content increasedfrom 34.571 ha-1 to 58.191 ha-1, with fixation of23.62 t ha-1 in 10 years, which corresponds to 86.621 ha-1 of COt It is concluded that agroecological management in an organic production system enables an increase in the level of organic matter of soils by recycling and sequestering atmospheric carbon, confirming the increased potential of organic agriculture to reduce greenhouse gas emissions and contribute to a reduction in global warming. <![CDATA[<b>Diversity of spiders in an almond <i>Prunus</i><i> dulcis</i> (Mill.)</b><b> D.A. Webb orchard in the Metropolitan Region of Chile (Central Chile)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100003&lng=en&nrm=iso&tlng=en The species of epigeal Araneae from an almond orchard located in the former El Mariscal Ranch (33036'30.5"S-70038'30.3"W) in the Metropolitan Region, Chile were investigated. The samples were taken using pitfall traps placed in two parallel transects, one within the orchard and the other in the adjacent uncultivated border, each with 5 traps. The sampling period extended from September to December 2006 and September to December 2007. The collected material was removed approximately every 15 days. The determination of families was made through taxonomic keys (Ramírez, 1999; Aguilera & Casanueva, 2005); the species were distinguished only by morphological differences. The total number of spiders collected was 2556, including 11 families and 37 species. The most abundant families, in decreasing order, were Linyphiidae, Gnaphosidae, Dysderidae and Anyphaenidae, which together included 72% of the total. Linyphiidae was the most abundant family during the two sampling periods. The families Anyphaenidae, Linyphiidae, Dyctinidae, Gnaphosidae and Salticidae accounted for 70% of the total species richness. Wandering spiders were dominant in the almond orchard, probably related to the disturbances due to agricultural practices. On the other hand, the uncultivated border showed a dominance of web-building spiders, probably due to the greater stability and complexity of the habitat.<hr/>Se caracteriza la araneofauna epigea de un cultivo de almendros ubicado en el ex fundo El Mariscal (33°36'30,5"S-70°38'30,3"O), Provincia Cordillera, Región Metropolitana, Chile. El muestreo se efectúa mediante trampas de intercepción (Barber) que se disponen en dos transectos paralelos, uno en la zona de cultivo y el otro en el borde adyacente con 5 unidades en cada lugar. Las trampas se renuevan quincenalmente entre septiembre y diciembre del año 2006 y en el mismo periodo del año 2007. Mediante el uso de claves (Ramírez, 1999; Aguilera y Casanueva, 2005) se reconocen familias y sus morfoespecies. Se colectan 2.556 individuos del orden Araneomorphae, pertenecientes a 11 familias y 37 morfoespecies. Las familias más abundantes, Linyphiidae, Gnaphosidae, Dysderidae y Anyphaenidae, en ese orden de importancia constituyen el 72% de la abundancia de la muestra. Sólo Linyphiidae coincidió en ambos años como la familia más abundante y por ende se reconoce como dominante. En cuanto a la composición, las familias Anyphaenidae, Linyphiidae, Dyctinidae, Gnaphosidae y Salticidae constituyen el 70% de la riqueza registrada en el total de la muestra. En la zona de cultivo se reconoce el predominio de arañas errantes, lo que tendría directa relación con condiciones oscilantes que ofrece el cultivo por las frecuentes perturbaciones que se ejercen en la aplicación de las prácticas de manejo agrícola. En cambio, en el borde se constata el predominio de arañas tejedoras, lo que tendría relación con las condiciones estables y de mayor complejidad de estratos que ofrece este hábitat. <![CDATA[<i>Vibration and noise levels emitted by two tractors</i>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100004&lng=en&nrm=iso&tlng=en A operação de tratores agrícolas impõe grande estresse físico e mental aos tratoristas. Este trabalho teve como objetivo avaliar os níveis de vibração e ruído emitidos por dois tratores agrícolas, defasados temporalmente, em diferentes rotações do motor (1700, 1850 e 2000 rpm). Nas avaliações foram utilizados um trator de 60,35 kW, fabricado em 1988, e um trator de 89,06 kW, fabricado em 2009, ambos não-cabinados e tracionando um arado de discos. As avaliações de ruído foram feitas com um medidor de pressão sonora (decibelímetro), no posto de operação da máquina. As avaliações de vibração foram feitas no assento do trator, utilizando um sistema de aquisição automática de dados com três acelerômetros, nos sentidos vertical e horizontal. Os resultados permitiram as seguintes conclusões: a operação de aração com os dois tratores apresentaram níveis de ruído acima do limite de 85 dB (A) para 8 horas de exposição diária, estabelecido pela NR-15, fazendo-se necessário o uso de dispositivos de proteção auricular durante sua execução. O trator mais antigo apresentou níveis de vibração que podem comprometer a saúde, segurança, conforto e eficiência do tratorista. O mesmo não ocorreu para o trator mais novo.<hr/>Tractor driving imposes a lot of physical and mental stress upon the operator. The aim of this work was to evaluate the vibration and noise levels emitted by tractors with different ages, under different motor rotations (1700, 1850 and 2000 rpm). In the evaluations, two agricultural tractors (a 1988 model year with 60.35 kW of power and a 2009 model year with 89.06 kW), without cabin were used, working with a plough. The noise evaluations were made with a sound level meter, in the driver's position. The vibration evaluations were made on the driving seat using an automatic acquisition data system with three accelerometers, in the vertical and horizontal planes. The results showed that the service with the tractors presented noise levels higher than the 85 dB(A) limit for 8 hours of daily exposure, established by the Brazilian Legislation on insalubrity. The need of hearing protection device use by the machine operators was observed. The older tractor presented vibration levels that could compromise health, safety, comfort and efficiency of the driver. This not occurs for the newer tractor. <![CDATA[<b>Effect of abscisic acid on the maturation of olive trees cv. </b><b>Arbequina</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100005&lng=en&nrm=iso&tlng=en Interventions which accelerate the fruit maturation of olives planted in cold climates are necessary to advance the harvest and not allow the fruit to be exposed to early freezes which may have negative effects on the quality of the oil. In Autumn (28 April) 2006 we applied 0, 100, 200, 300 and 400 mg-L-1 abscisic acid (ABA) to trees of the variety of Arbequina at the beginning of veraison in an orchard in Melipilla, Metropolitan Region, Chile, in order to evaluate its effect on the acceleration of fruit maturation. The experimental design was completely randomized; the means of the treatments were compared by ANOVA and Tukey's test (p<0.05). The application of ABA produced a strong defoliation of the trees, together with a marked fruit fall, especially at 300 and 400 mg-L-1. Fruit maturation was retarded, expressed as a delay in the development of color for trees treated with 400 mg-L-1 ABA. The treatments did not produce an effect on the oil content measured as a proportion of dry weight. The following year (2007), those trees treated with 300 and 400 mg-L-1showed a significant reduction in fruit harvested per tree, which may be due to an effect of the ABA applied on the processes of induction or initiation of bud differentiation.<hr/>Labores que generen anticipos en la maduración de la fruta de olivos plantados en climas fríos, son necesarias para adelantar las cosechas y no exponer a la fruta a heladas tempranas que pudieran tener efectos negativos en la calidad del aceite. Durante el otoño (28 de abril) de 2006, en un olivar de la variedad Arbequina (Comuna de Melipilla, Región Metropolitana, Chile), se aplicó al momento de envero: 0, 100, 200, 300 y 400 mg-L-1 de ácido abscísico (ABA) para evaluar su efecto en el adelanto de la maduración de los frutos. El diseño experimental fue completamente al azar y las medias de los tratamientos se compararon con la prueba de Tukey (p<0.05). La aplicación de ABA provocó una fuerte defoliación en los árboles, junto con una marcada caída de frutos, principalmente para 300 y 400 mg-L-1 (p<0.05). Además se retrasó la maduración de la fruta, expresado en la demora del desarrollo de color para los árboles tratados con 400 mg-L-1 de ABA. No hubo efecto de los tratamientos en el contenido de aceite en base a materia seca. Al año siguiente (2007), los árboles tratados el 2006 con 300 y 400 mg-L-1 redujeron significativamente la cantidad de fruta cosechada por árbol, lo cual podría deberse a un efecto de la aplicación de ABA en el proceso de inducción o inicio de la diferenciación de las yemas. <![CDATA[<i>Using of the time domain reflectometry to evaluate the phosphorus distribution in soils columns fertirrigateds</i>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100006&lng=en&nrm=iso&tlng=en Estudos direcionados para o monitoramento da dinâmica de solutos no solo, sob áreas fertirrigadas, são de fundamental importância, pois permitem adotar medidas de manejo da fertirrigação possibilitando disponibilizar o nutriente nos locais de maior densidade radicular. Objetivou-se com esse trabalho avaliar, usando a técnica da TDR, a distribuição de fósforo em colunas de Neossolo Quartzarênico (RQ) e Latossolo Vermelho (LV) fertirrigadas com MAP. Foram realizadas fertirrigações com MAP nas colunas e determinados os teores de água (8) e condutividades elétricas do solo (CEs) com uso de sondas de TDR instaladas em várias profundidades, sendo a concentração do nutriente estimada som uso de modelos matemáticos. Em ambos os solos o fósforo ficou adsorvido a camada superficial, não alcançado os 12 cm de profundidade, independentemente do momento da fertirrigação.<hr/>Studies to monitor soil solute dynamics in fertigated areas are of great importance, because they allow the adoption of measures of fertigation management, making the nutrients available in the places of greatest root density. The objective of this study was to evaluate, using the TDR technique, the phosphorus distribution in Neosol Quartizarenic (RQ) and Red Latossol (LV) soil columns fertigated with MAP. The MAP fertigations were performed in the columns; the soil water content (8) and soil bulk electric conductivity (CEs) were obtained using (with) TDR probes installed at various depths, and the nutrient concentration was estimated using mathematical models. In both soils the phosphorus was adsorbed in surface layer, not reaching 12 cm depth, regardless of the moment of the fertigation was started. <![CDATA[<i>Nutrient cycling and decomposition of crop residues of four cover crops for soil</i>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100007&lng=en&nrm=iso&tlng=en El mijo y el sorgo pueden ser utilizados como cultivos de protección para el suelo y el reciclado de nutrientes en suelos de baja fertilidad. Este estudio evaluó la descomposición y el ciclo de nutrientes en los residuos aéreos de cuatro plantas en un suelo arenoso, sin fertilizantes o riego. Los tratamientos consistieron en las plantas de mijo (cultivar ENA 2 BRS 1501), el sorgo (BRS 310) y malezas (MA). Las muestras conseguidas a los 87 días después de la siembra fueron estratificadas en hojas y tallos, colocadas y distribuidas en la superficie de las parcelas. La descomposición de la biomasa y la liberación de nutrientes fueron controladas mediante la acumulación de material, realizada 10, 20, 30, 60, 90 y 120 días después del corte. El mijo (ENA 2) acumuló la mayor cantidad de biomasa y materia seca en los tallos, mayor contenido de N, P y K en los residuos, seguido por sorgo, mijo (BRS 1501) y malezas. Con la excepción de K, hubo una rápida liberación de nutrientes por parte de las malezas MA, mientras que en el mijo (ENA 2) la liberación fue más gradual. BRS1501 y el BRS 310 mostraron valores intermedios y similares. La mayor materia seca de ENA 2 y su mayor tiempo de descomposición indican que se recomienda su uso como cultivo de cobertura y para reciclaje de nutrientes.<hr/>Pearl millet and sorghum can be used as cover plants for soil and recycling of nutrients in soils of low fertility. This study evaluated the nutrient cycling and decomposition of crop residues of four cover crops in sandy soil, without fertilizer or irrigation. The treatments consisted of two pearl millet genotypes (cultivar ENA 2 and BRS1501), sorghum genotype BRS 310 and non- cultivated plants (weeds - VE). Samples of shoots, stratified into leaves and stems collected 87 days after planting were placed in bags and distributed on the surface of the plots. The dry matter decomposition and nutrient release were monitored through collection of material from the bags 10, 20, 30, 60, 90 and 120 days after cutting. The ENA 2 showed the greatest amounts of biomass and dry weight of stems and higher levels of N, P and K in its remaining detritus, followed by sorghum, BRS 1501 and VE. With the exception of K, there was a rapid release of all nutrients by VE, while the ENA 2 nutrient release was more gradual, and was intermediate and similar for BRS 1501 and sorghum. The greater dry weight and slower decomposition of cultivar ENA 2 make it the recommended genotype for use as soil cover and nutrient recycling. <![CDATA[<i>Parameters indicators of the potential of nitrogen mineralization of organic compounds</i>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100008&lng=en&nrm=iso&tlng=en O presente trabalho objetivou avaliar as relações entre características químicas de 15 tipos de compostos orgânicos e o fornecimento de nutrientes para as plantas. Para isso, experimentos de incubação de solo foram montados em laboratório, utilizando-se copos plásticos contendo 50 g de um Argissolo Vermelho-Amarelo distrófico, no qual foram incorporados 374 mg de massa seca dos compostos. O delineamento experimental foi em blocos casualizados com 16 tratamentos (15 compostos e testemunha), 4 tempos de incubação (3, 7, 14 e 28 dias) e 3 repetições. Em cada data de coleta analisou-se o teor de N inorgânico do solo e, aos 28 dias, determinaram-se o P, K, Ca e Mg do solo. Das variáveis estudadas (lignina, polifenóis, cinzas, C, N, P, K, Ca, Mg, lignina/N e C/N), apenas a relação C/N apresentou uma fraca correlação positiva com a mineralização de nitrogênio. Observaram-se diferenças entre os compostos no fornecimento de P e K ao solo, mas não houve diferenças quanto ao Ca e Mg. Conclui-se que as características químicas avaliadas dos compostos testados não demonstraram promissoras como indicadoras do potencial de fornecimento de nutrientes pelos compostos.<hr/>The objective of the present study was to evaluate the relationships between the chemical characteristics of 15 types of organic composts and the release of nutrients to the soil. Laboratory soil incubations were carried using plastic cups, where 50 g of a dystrophic Red Yellow Argisol (Ultisol) were amended with 0.374 g of each compost. The design was in randomized blocks with 16 treatments (15 types of compost plus a control) and 4 incubation periods (3, 7, 14 and 28 days) with three replications. At the end of each period, the soil inorganic N was determined, but soil P, K, Ca and Mg were determined only at day 28. The composts had different effects on soil N, causing from mineralization to immobilization. Among the evaluated characteristics of the composts (lignin, poliphenols, ashes, C, N, P, K, Ca, Mg, lignin:N, and C:N) only the C:N ration had a significant correlation with N mineralization. The composts also varied regarding the supply of P and K to the soil, but there were no differences in the supply of Ca and Mg. In conclusion, the chemical characteristics of the composts that were evaluated were not useful indicators of the potential nutrient supply by the composts. <![CDATA[<i>Yield of</i> Brachiaria brizantha <i>cv. Xaraes in different management and levels of fertilization, rest periods and seasons</i>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100009&lng=en&nrm=iso&tlng=en Experimentos já foram conduzidos no Leste do Estado de Minas Gerais visando à avaliação de gramíneas forrageiras onde destacou-se a Brachiaria brizantha cv. Xaraés. Diante disso, decidiu-se intensificar a pesquisa conduzindo-se um experimento em esquema de parcelas sub-subdivididas, tendo nas parcelas um esquema fatorial 2 x 2 (épocas climáticas e manejos de adubação), nas subparcelas quatro períodos de descanso e nas sub-subparcelas seis níveis de adubação, no delineamento inteiramente casualizado, com quatro repetições. As épocas climáticas foram outono/inverno e primavera/verão. Os períodos de descanso foram de 21, 28, 35 e 42 dias. Os manejos de adubação foram convencional e fertirrigação. Para diferenciar as doses de adubação no tratamento fertirrigado, utilizou-se a aspersão em linha. As doses de adubação tiveram uma relação entre nitrogênio e potássio de 1 N: 0,8 K2O e foram de 0, 15, 39, 64, 83 e 100% da referência (700 e 560 kg de N e K2O). A produtividade de matéria seca foi obtida por meio do material seco em estufa ventilada a 60 °C, por 72 h. Verificou-se, em geral, que a estação seca apresentou menor produtividade de MS; porém, em média, a produtividade obtida na estação outono/inverno foi de 75% daquela obtida na estação primavera/verão. Os manejos de adubação não influenciaram os valores de produtividade de MS, porém o aumento da dose de adubação proporcionou efeito linear positivo no capim-xaraés fertirrigado na estação outono/inverno e quadrático nos demais tratamentos. Os períodos de descanso proporcionaram efeito quadrático apenas no tratamento fertirrigado e estação outono/inverno.<hr/>In Experiments conducted in the eastern part of Minas Gerais in Brazil to evaluate the forage grasses, Brachiaria brizantha cv. Xaraes proved to be exceptional. Thus, it was decided intensify the research on this grass, conducting an experiment in a sub-split-plot, and plots a 2 x 2 factorial (seasons and management of fertilization), four rest periods in the subplots and six levels of fertilization in the sub-subplots, in a completely randomized design with four replications. The seasons were fall/winter and spring/summer. The rest periods were 21, 28, 35 and 42 days. The management consisted of application of nitrogen and potassium fertilizers scattered conventional and fertigation. To differentiate the dose of fertilization in the treatment fertirrigated, it was used a line-source irrigation system. The fertilization doses had a ratio of nitrogen and potassium, 1 N: 0.8 K2O and were 0, 15, 39, 64, 83 e 100% of the reference (700 e 560 kg of N and K2O). Dry matter was obtained by means of the dry material in ventilated stoves at 60 °C, for 72 h. The dry season had DM yield, but on average, the yield in the autumn/winter was 75% of that obtained in the spring/summer. The management of fertilization did not influence the values of DM yield, but increasing the dose of fertilization has positive linear effect on xaraes-grass fertigated in the autumn/winter and quadratic in the other treatments. The rest periods provided quadratic effect only in the treatment fertigated in fall/winter season. <![CDATA[<b>Physical and rheological characterization of seeds of three legume trees</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100010&lng=en&nrm=iso&tlng=en El algarrobo chileno (Prosopis chilensis (Mol) Stuntz), la tara (Caesalpinea spinosa (Mol) Kuntze) y la acacia de las tres espinas (Gleditsia triacanthos L) ofrecen un interesante potencial para promover el desarrollo de las zonas áridas. En el endosperma de sus semillas existe una goma del tipo galactomanano que posee propiedades viscosantes y estabilizadoras de emulsiones. Se realizó una investigación para evaluar las características físicas de las vainas y semillas y las propiedades reológicas de las gomas de estas especies. Se estudiaron frutos de cinco ecotipos de algarrobo (Región de Coquimbo y Región Metropolitana), de tara (Región de Coquimbo) y de acacia de las tres espinas (Región Metropolitana). Se midieron las dimensiones de las vainas, número de semillas/ vaina, peso de semillas, rendimiento y parámetros de color de cotiledón y goma y las propiedades reológicas de las gomas extraídas. Las gomas se extrajeron manualmente y se secaron a 50 oQ En algarrobo, las semillas pesaron 0,04 g y el rendimiento de goma varió entre 25,5 y 31,5%. Las semillas de tara pesaron 0,14 g y las de acacia de las tres espinas 0,16 g, con un rendimiento de goma 31,0 y de 40,1% y respectivamente. Las gomas presentaron una alta luminosidad y contribución del amarillo y baja contribución de rojo. Las dispersiones, en todas las gomas estudiadas, presentaron un comportamiento no newtoniano del tipo Herschel-Bulkley, correspondiendo a un fluido inelástico, independiente del tiempo. La viscosidad aparente de la goma de algarrobo fluctuó entre 0,020 y 0,12, la de tara entre 0,06 y 1,3, y la de acacia de las tres espinas entre 0,034 y 0,08 Pa*s. Las gomas de estas especies tienen características reológicas que permitirían su aplicación en alimentos.<hr/>The Chilean algarrobo ("Prosopis chilensis (Mol) Stuntz), the tara (Caesalpinea spinosa (Mol) Kuntze) and the honey locust (Gleditsia triacanthos L) have an interesting potential for the development of arid zones. The endosperm of the seeds of these species has a galactomannan-type gum which has the property of thickening and stabilizing emulsions. This study evaluates the physical characteristics of the pods and seeds, and the rheological properties of the gums of these species. We studied fruits of five ecotypes of algarrobo (Coquimbo and Metropolitan Regions), of tara from the Coquimbo Region and of honey locust (three-spined acacia) from the Metropolitan Region. We measured the dimensions of the pods, number of seeds per pod, seed weight, gum yield and color parameters of the cotyledon and gum, and the rheological properties of the gums extracted. Gums were extracted manually and dried at 50° C. The seeds of algarrobo weighed 0.04 g; their gum yield varied between 25.5% and 31.5%. The seeds of tara weighed 0.14 g and those of the acacia 0.16 g, with a gum yield of 31.0% and 40.1%, respectively. The gums had high luminosity and high contribution of yellow, along with low contribution of red. The dispersions of all the studied gums showed a non-Newtonian Herschel-Bulkley behavior corresponding to an inelastic fluid, independent of time. The apparent viscosity of the gum of algarrobo fluctuated between 0.020 and 0.12; that of tara between 0.06 and 1.3, and that of honey locust between 0.034 and 0.08 Pa*s. The gums of these species have rheological characteristics which would allow their addition to foods. <![CDATA[<b>Evaluation of entomopathogenic fungi as biological control agents <i>Rhipicephalus (Boophilus) microplus</i> (Canestrini, 1887) (Acari: Ixodidae)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100011&lng=en&nrm=iso&tlng=en The aim of this study was to evaluate in the laboratory different isolates and concentrations of conidia of Metarhizium anisopliae (Metschnikoff, 1879) Sorokin, 1883 and Beauveria bassiana (Balsamo) Vuillemim, 1912 for control of the cattle tick. The conidial suspensions were prepared from fungi grown in rice medium in polypropylene bags. The tests were performed by immersion of engorged females collected from animals not treated with acaricides. The experimental design was completely randomized with 20 treatments and 5 repetitions, each consisting of 5 females. The mortality rate caused by the fungus M. anisopliae ranged from 92 to 100%, while for B. bassiana it was 44 to 100%; mortality was greater at concentrations of 10(8) and 10(9) conidia mL-1 suspension. The isolates B. bassiana Fitossan 1 and M. anisopliae PL 43 (both at 10(9) conidia mL-1) and Fitossan 4 (10(8) conidia mL-1) within 14 days of treatment killed 100%, 92% and 88% of the engorged females, respectively. In general there was no difference in the weight of eggs from females treated with the same isolate at concentrations of 10(7), 10(8) and 10(9) conidia mL-1, although isolates of M. anisopliae had lower weight. The efficiency of control ranged from 0% (control with water) to 31.30% (M. anisopliae Fitossan 4, 10(8) conidia mL-1).<hr/>El objetivo de este trabajo fue evaluar diferentes colonias aisladas en concentraciones de Metarhizium anisopliae (Metschnikoff, 1879) Sorokin, 1883 y de Beauveria bassiana (Balsamo) Vuillemim, 1912 para el control de la garrapata común del vacuno. La multiplicación de conidias fue realizada a partir de hongos inoculados en arroz precocido estéril. Los ensayos de inmersión fueron realizados sobre garrapatas adultas ingurgitadas o teleoginas colectadas de bovinos no tratados con acaricidas. El diseño experimental fue completamente al azar con 20 tratamientos y cinco repeticiones, siendo cada una de estas constituidas por cinco hembras. La mortalidad de las teleoginas ocasionada por M. anisopliae fue variable entre 92 a 100% y para B. bassiana este parámetro varió entre 44 a 100%, observándose que la mortalidad fue superior en las concentraciones de 10(8) y 10(9) conidias mL-1, destacándose las cepas de B. bassiana Fitossan 1 e M. anisopliae PL 43 (ambos 10(9) conidias mL-1) y Fitossan 4 (10(8) conidias mL-1), que a los 14 días de tratamiento habían eliminado el 100, 92 y 88 % de las teleoginas, respectivamente. En general, no existió diferencia en relación al peso de los huevos provenientes de hembras tratadas con el mismo aislado en las concentraciones de 10(7), 10(8) y 10(9) conidia .mL-1, aunque se obtuvieron pesos inferiores para las cepas de M. anisopliae. La eficiencia del control varió de 0% (control) a 31,30% (M. anisopliae Fitossan 4, 108 conidias.mL-1). <![CDATA[<i>Selection of</i> Trichogramma <i>sp. (Hymenoptera: Trichogrammatidae) species parasitizing eggs of</i> Anagasta kuehniella <i>(Lepidoptera: Pyralidae)</i>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100012&lng=en&nrm=iso&tlng=en En forma espontánea las especies de Trichogramma se encuentran parasitando huevos de lepidópteros, donde diferentes especies de parasitoides prefieren a diferentes huéspedes. Para lograr el éxito en el programa de control biológico usando Trichogramma se deben estudiar las especies más emparentadas con el huésped alternativo. Se investigaron cuatro especies de Trichogramma: Trichogramma acacioi Brun, Moraes y Soares, Trichogramma atopovirilia y Oatman Platner, Trichogramma exiguum Pinto y Platner y Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae). Se estudiaron tres indicadores: el parasitismo en un periodo de 24 horas, parasitismo diario durante la edad adulta y el tiempo de fertilidad del huésped Anagasta kuehniella (Zeller) (Lepidóptera: Pyralidae). T. acacioi y T. pretiosum tuvieron las más altas tasas de parasitismo diario durante la edad adulta y el mayor tiempo de fertilidad, mientras la especie que presentó el mejor rendimiento fue T. exiguum. Por lo tanto, el parasitismo en el periodo de 24 horas y de tiempo de fertilidad son las más eficientes formas de selección de las especies, pero con limitaciones en comparación con el parasitismo diario en la edad adulta.<hr/>Trichogramma species are natural egg parasites of various species of Lepidoptera. However, different species of parasitoid prefer different hosts. Therefore, to achieve success in the biological control program using Trichogramma, it is necessary to study the species most related to the alternative host. Four species of Trichogramma were investigated: Trichogramma acacioi Brun, Moraes & Soares, Trichogramma atopovirilia & Platner Oatman, Trichogramma exiguum Pinto & Platner and Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae). Three indicators were studied: parasitism within a 24 h period, daily parasitism rate during the adult stage and the fertility life table of the host Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae). T. acacioi and T. pretiosum showed the highest daily parasitism rate during the adult stage and the greatest effect on the fertility life table, while the species with best performance was T. exiguum. Thus parasitism within 24-h period and host fertility life table were the most efficient systems of selection of species, but with limitations compared to daily adult parasitism rate. <![CDATA[<b>Damage caused by citrus canker on Valencia sweet orange yield</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100013&lng=en&nrm=iso&tlng=en The citrus canker, caused by Xanthomonas axonopodis pv. citri, is one of the main citrus diseases and has threatened the world's citriculture. In this study, the damage caused by citrus canker was quantified in a sweet orange culture, cv. Valencia [Citrus sinensis (L.) Osb.], grafted over 15 year-old Rangpur lime (C. limonia Osb.), in the municipality of Guatambu, SC, Brazil, in the crop of 2004/05. Evaluations of the number of fruits per plant (NF), fruit yield per plant (P), citrus canker incidence on the fruit (IFR), and incidence (IL) and severity (SV) of citrus canker on 80 leaves per orange tree were performed in the harvest period, applying diagrammatical scales. Plants had large variation in SV (0.16%-1.09%), IL (12.50%-56.25 %) and IFR (12.30%-56.09%). Linear regressions were significant between IL x SV, NF x SV, P x IFR, and NF x IFR. There was no significant difference (p>0.05) between the mean estimated values of IL in different quadrants of the crowns of the orange trees (N, S, L and O). Each 1% increase in IFR reduced 2.16 kg and 21.3 fruits per tree.<hr/>El cancro cítrico causado por Xanthomonas axonopodis pv. citri, es una de las principales enfermedades de los cítricos y tiene amenazada la industria de los cítricos en todo el mundo. En este trabajo se cuantificó el daño causado por el cancro cítrico en la producción de naranja dulce cv. Valencia /Citrus sinensis (L.) Osb.] injertada en limón 'Cravo' (C. limonia Osb.), con 15 años de edad, en el municipio de Guatambú, SC, Brasil, en la cosecha 2004/05. En el momento de la cosecha, se evaluó el número de frutos por planta (NF), el rendimiento de frutos por planta (R), la incidencia de cancro en los frutos (IFR) y la incidencia (IFL) y severidad (SV) de cancro en 80 hojas/planta, utilizando escalas diagramáticas. Las plantas presentaron gran variación en SV (de 0,16 a 1,09%), IFL (12,50 a 56,25%) y IFR (12,30 a 56,09%). Fue posible adaptarse regresiones lineales simples entre IFL x SV, NFx SV, R x IFR y entre NFx IFR. No hubo diferencias significativas (p> 0,05) entre los medios de IFL estimados en los diferentes cuadrantes de la copa de las plantas (N, S, E y O). A cada incremento de 1% en IFR se reduce la producción por planta en 2,16 kg y 21,3 frutos. <![CDATA[<i>Abundance, richness and diversity of</i> Eiphosoma <i>Cresson 1865 (Hymenoptera, Ichneumonidae) species associated with organic crops</i>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100014&lng=en&nrm=iso&tlng=en O objetivo deste trabalho foi caracterizar a fauna de Eiphosoma Cresson, 1865 (Hymenoptera, Ichneumonidae, Cremastinae) em áreas de agricultura orgânica, em relação à abundância, riqueza e diversidade de espécies. Foram identificadas quatorze espécies de Eiphosoma, das quais duas são novos registros para o Brasil e três são novas espécies. A horta com intensidade mediana de manejo e diversidade vegetal apresentou os maiores valores de abundância, riqueza e diversidade em relação às hortas com maior e menor intensidade de manejo. As variáveis climáticas demonstraram exercer menor influência na fauna de Eiphosoma do que as características (composição e manejo) das hortas.<hr/>The aim of this study was to characterize the Eiphosoma Cresson, 1865 (Hymenoptera, Ichneumonidae, Cremastinae) fauna in areas of organic crops production, in relation to abundance, richness and diversity of species. Fourteen Eiphosoma species were identified, two new records to Brazil and three are new species identified. The system with median intensity management showed the highest values of abundance, richness and diversity in relation with higher and lower intensity of management. The climate variables showed less influence on the Eiphosoma fauna than the characteristics (composition and management) of the systems. <![CDATA[<b>The serine protease inhibitors and plant-insect interaction</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100015&lng=en&nrm=iso&tlng=en Plants respond to a physical injury or biological attack by producing, among other compounds, an arsenal of defense proteins, secondary metabolites and phytohormones, all necessary for plant survival. Defense proteins include the group of serine protease inhibitors (SPI), proteins that interact with the active site of their target enzymes. The activity of these protease inhibitors has been exploited to combat insect pests. SPI is an interesting alternative to produce plants with improved resistance characters through selection in the field or expressing their genes in sensitive plants by genetic engineering. The alternative that these natural products offer makes them valuable for the control of several crop pests.<hr/>Frente a una agresión física o biológica, las plantas responden bioquímicamente sintetizando, entre otros, un arsenal de proteínas de defensa, metabolitos secundarios y fitohormonas, todos los cuales le permiten sobrevivir. Dentro del grupo de proteínas de defensa se encuentran los inhibidores de serin proteasas (SPI), los cuales interaccionan con el sitio activo de sus enzimas blanco. La actividad de estos inhibidores de proteasas se ha aprovechado en su aplicación para combatir insectos plaga. Los SPI representan una interesante alternativa para producir plantas con mejores características de resistencia, ya sea a través de selección en campo o bien expresando sus genes en plantas sensibles por medio de ingeniería genética. Estos productos innatos de las plantas ofrecen alternativas que los hacen valiosos en el control biológico de plagas de varios cultivos. <![CDATA[<b>Andean Amerindians and agricultural cooperatives during the Junta de Adelanto de Arica</b>: <b>Lluta</b><b>, Azapa and the Andes foothills (1962-1976)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-34292012000100016&lng=en&nrm=iso&tlng=en This article examines from a historical perspective the implementation of Cooperatives in the Department of Arica (1962-1976) and the participation of Andean farmers in these organizations. We describe the policies of the Corporation of Agrarian Reform, specifically, the actions of the Junta de Adelanto of Arica to promote association among indigenous peasants in the valleys and mountains of the extreme north of Chile.<hr/>El presente artículo analiza desde una perspectiva histórica la implementación de cooperativas en el Departamento de Arica (1962-1976) y la participación de agricultores andinos en este tipo de organizaciones. Para ello, se describen las políticas de la Corporación de Reforma Agraria y, puntualmente, las acciones que la Junta de Adelanto de Arica realizó para fomentar la asociatividad entre los campesinos indígenas de los valles y precordillera del extremo norte del país.