ABSTRACT This work has as a problem the study of the strategic guidelines of agro-livestock entrepreneurship of the Central Chaco. The Methodology used in this work has had a qualitative-quantitative approach, with a descriptive scope, applying in-depth interviews to a total of ten managers of agricultural farms. The main activity is the production of bovine meat. 47% of the farms are used for pasture, 2% for agricultural cultivation and 2% for infrastructure, the space dedicated to Forest represents 49%. The most appropriate strategies to achieve a greater development include applying adequate records to measure and control the development of the animals in order to deliver animals with a better record of weight in an appropriate season of sale. Apply a vaccination plan to avoid diseases in cattle. Weed control is required due to its implication in the diet of the animals and therefore their weight gain, which is why it is necessary to have a soil management plan. The construction of water and food reservoirs is necessary to mitigate the action of the climate. Finally, the training of personnel is an aspect that is required for a better management of plots, water and food. More than formal training, participation in talks held by state or private entities that offer technical assistance would be sought.

RESUMEN Este trabajo tiene como problemática el estudio de los lineamientos estratégicos de emprendimiento agro ganaderos del Chaco Central. La Metodología utilizada en este trabajo ha tenido un enfoque cuali-cuantitativo, con un alcance exploratorio, aplicando entrevistas en profundidad a un total de diez encargados de las fincas agropecuarias. La principal actividad es la producción carne bovina. EL 47% de las fincas es destinado a la pastura, 2% a cultivo agrícola y 2% a la infraestructura, el espacio dedicado a Bosque representa el 49%. Las estrategias más adecuadas para lograr un mayor desarrollo incluyen aplicar registros adecuados para medir y contralar el desarrollo de los animales a fin de entregar animales con mejor registro de peso en una época de venta adecuada. Aplicar un plan de vacunaciones para evitar enfermedades en el ganado. Se requiere el control de malezas por su implicancia en la dieta de los animales y por ende su ganancia de peso, por ello es necesario contar con un plan de manejo del suelo. Se hace necesaria la construcción de reservorios de agua y alimentos para mitigar la acción del clima. Por último, la capacitación del personal es un aspecto que se impone para un mejor manejo de las parcelas, del agua y el alimento. Más que una capacitación formal se buscaría la participación de charlas realizadas por entes estatales o privados que ofrezcan asistencia técnica.

SUMMARY: This study provides an updated vision of the study of Geometric Morphometrics and its most recent application in ecology and evolutionary biology, covering a wide variation in methodology occurring in the last 5 years since the first version published in the International Journal of Morphology. Geometric Morphometrics is a tool that allows evaluating morphological variations with underlying factors, with a higher sensitivity than traditional morphology, so that minimum changes of morphological variation can be detected. Therefore, it has turned into an outstanding tool to answer questions of comparative biology focused on anatomic characters. At the beginning, it was a tool mainly used to answer taxonomic questions and for differentiation at individual, population or species level. However, in the last years, the number of questions and problematic on which it is applied, has diversified considerably, turning it into a very accurate tool to answer questions of morphological variation in ecologic and evolutionary contexts. Almost half a decade has elapsed since the last revision of the method, so this work is intended to analyze the methodological changes and the new approaches used in Geometric Morphometrics, including a brief introductory guideline to these new methods, their uses and applications.

RESUMEN: La presente revisión entrega una visión actualizada del estudio de la morfometría geométrica y sus aplicaciones más actuales en ecología y biología evolutiva, metodología con una amplia variación en los últimos 5 años de su primera versión en International Journal of Morphology. La Morfometría geométrica es una herramienta que permite evaluar las variaciones morfológicas con factores subyacentes, siendo una herramienta más sensible que la morfometría tradicional, lo que permite detectar mínimos cambios de variación morfológica. Lo que la ha vuelto una herramienta notable para responder preguntas de biología comparada centradas en caracteres anatómicos. En sus comienzos fue una herramienta usada principalmente para responder preguntas taxonómicas, y para diferenciar a nivel de individuos, poblaciones o especies. No obstante, en los últimos años la cantidad de preguntas y problemáticas en las que se aplica, ha diversificado considerablemente, pasando a ser una herramienta muy precisa para responder preguntas de variación morfológica en contextos ecológicos y evolutivos. Ya ha pasado casi media década desde la última revisión del método, por lo que éste trabajo tiene como objetivo analizar los cambios metodológicos y los nuevos enfoques usados en Morfometría geométrica, y presentar una pequeña guía introductoria a éstos nuevos métodos, sus usos y aplicaciones.

ABSTRACT Background: Brucellosis is a common zoonosis and in many countries it is a prevalent health problem. In Paraguay, no evidence has been found of the knowledge that dairy herd workers have and the preventive practices they use. Objective: To evaluate the knowledge, prevention and biosecurity practices on Brucellosis of workers exposed to risk in dairy herds of Caaguazú. Materials and methods: A cross-sectional study was carried out in a representative sample of livestock establishments in the Department of Caaguazú. From May to June 2017, 720 workers from 360 dairy farms were interviewed, using a structured questionnaire with closed questions. Information on the knowledge, prevention and biosecurity practices on brucellosis was obtained. Result: The median age of the workers was 34 years, 70% were men. 11.7% were illiterate and 62.1% only completed the primary. 90% worked as a tambero/milker. Sixty-four percent said they did not know about the disease, 73.6% did not know how the disease was acquired, 71.5% never received information about brucellosis. 73.3% had no knowledge of preventive practices. All consumed unpasteurized dairy byproducts, mainly Paraguayan cheese Conclusion: There is a lack of knowledge of the disease and the way of transmission. Risk practices are frequent. It is necessary to implement education and awareness programs on brucellosis.

RESUMEN Introducción: La Brucelosis es una zoonosis común y en muchos países es un problema sanitario prevalente. En Paraguay no se ha encontrado evidencia de los conocimientos que tienen los trabajadores de hatos lecheros y las prácticas preventivas que utilizan. Objetivo: Evaluar el conocimiento, las prácticas de prevención y de bioseguridad sobre Brucelosis de los trabajadores expuestos a riesgo en hatos lecheros del departamento de Caaguazú, Paraguay. Materiales y métodos: Se realizó un estudio transversal, en una muestra representativa de establecimientos ganaderos del Departamento de Caaguazú. De mayo a junio de 2017 se entrevistó a 720 trabajadores de 360 hatos lecheros, utilizando un cuestionario estructurado, con preguntas cerradas. Se obtuvo información de los conocimientos, prácticas de prevención y bioseguridad sobre Brucelosis. Resultados: La mediana de edad de los trabajadores fue 34 años, 70% eran hombres. El 11,7% era analfabeto y 62,1% solo culminó la primaria. El 90% se desempeñaba como tambero/ordeñador. El 64% manifestó que no conocía la enfermedad, 73,6% ignoraba la forma en que se adquiere la enfermedad, 71,5% nunca recibió información acerca de la Brucelosis. El 73,3% no tenía conocimientos de las prácticas preventivas. Todos consumían subproductos lácteos sin pasteurizar, principalmente queso paraguay Conclusión: Existe desconocimiento de la enfermedad y la forma de transmisión. Las prácticas de riesgo son frecuentes. Es necesario implementar programas de educación y concienciación sobre la Brucelosis.

RESUMO Objetivo: Para avaliar a eficácia e a segurança da reposição do disco lombar total em pacientes com discopatia degenerativa (L3-L4, L4-L5, L5-S1). Método: 143 pacientes com dor lombar com ou sem radiculopatia, os quais obedecem a critérios radiográficos, foram submetidos à artroplastia anterior entre 2000 e 2016. Avaliamos antes e após a cirurgia, três, seis, 12 e 24 meses, a Doença de Oswestry (ODI), escala analógico-visual (EVA), satisfação do paciente, critérios de sucesso, altura do disco e amplitude de movimento do segmento operado. Resultados: 50 homens e 93 mulheres. A idade foi de 39,5. 13 pacientes (9%) com dissectomia prévia. Nível L5-S1 97 pacientes (67,8%). Nível L4-L5 45 pacientes (31,5%) e um paciente L3-L4 nível (0,6%). A ODI entre o pré-operatório e os 24 meses pós-operatórios reduziu 53,86%. O EVA na dor lombar reduziu 63,83% nos 24 meses depois, em comparação com dor lombar, e pré-operatória com radiculopatia diminuiu 60,20%,mudança estatisticamente significativa (p ≤ 0,5). 82% completamente satisfeitos e satisfeitos 18%. A altura do disco aumentou 12mm em média (p <0.001). O movimento do segmento afetado aumentou de 4° para 7°, após a cirurgia (p <0,004). Conclusão: A artroplastia lombar de um segmento é recomendada como um tratamento eficaz para pacientes com doença degenerativa do disco, que atendem aos critérios de inclusão e lumbalgia sozinhos ou com um componente radicular. Nível de Evidência III: Revisão sistemáticab de Estudos de Nível III.

ABSTRACT Objective: The objective of this longitudinal retrospective study is to assess the efficacy and safety of total lumbar disc replacement in patients with degenerative discopathy (L3-L4, L4-L5, L5-S1). Methods: One hundred and forty-three patients with low back pain, with or without radiculopathy, who met the radiographic criteria underwent anterior arthroplasty between 2000 and 2016. The Oswestry disability index (ODI), the visual analog scale (VAS), patient satisfaction, success criteria, disc height, and range of motion of the operated segment were evaluated preoperatively and at 3, 6, 12, and 24 months following surgery. Results: There were 50 men and 93 women, with an average age of 39.5 years, 13 patients (9%) with previous discectomy. The arthroplasty was performed at level L5-S1 in 97 patients (67.8%), at level L4-L5 in 45 patients (31.5%), and at level L3-L4 in 1 patient. Between the preoperative period and 24 months following surgery, the ODI decreased by 53.86%, the VAS for low back pain decreased by 63.83%, and low back pain with radiculopathy decreased by 60.20%, all statistically significant (p ≤ 0.5). Eighty-two percent of the patients were completely satisfied and 18% were satisfied. There was an average increase in disc height of 12 mm (p <0.001). The range of motion of the affected segment increased by 4° to 7° after surgery (p <0.004). Conclusions: Lumbar arthroplasty of a segment is recommended as an effective treatment for patients with degenerative disc disease with low back pain with or without a root component who meet the inclusion criteria. Level of Evidence III, Systematic reviewb of Level III studies.

RESUMEN Objetivo: Evaluar la eficacia y la seguridad del reemplazo total de disco lumbar en pacientes con discopatía degenerativa (L3-L4, L4-L5, L5-S1), mediante un estudio longitudinal retrospectivo. Métodos: Ciento cuarenta y tres pacientes con lumbalgia, con o sin radiculopatía, cumpliendo criterios radiográficos fueron sometidos a artroplastia por vía anterior entre 2000 y 2016. Se evaluaron antes y tres, seis, 12 y 24 meses después de la cirugía el Índice de Discapacidad de Oswestry (ODI), escala analógica visual (EVA), satisfacción del paciente, criterios de éxito, altura discal y rango de movimiento del segmento operado. Resultados: Cincuenta hombres y 93 mujeres. Edad promedio 39,5, 13 pacientes (9%) con discectomía previa. Nivel L5-S1 97 pacientes (67,8%). Nivel L4-L5 45 pacientes (31,5%) y un paciente nivel L3-L4 (0,6%). El ODI entre el preoperatorio y 24 meses postoperatorios redujo 53,86%. La EVA en la lumbalgia redujo 63,83% 24 meses después en comparación con el preoperatorio y lumbalgia con radiculopatía disminuyó 60,20%. Cambio estadísticamente significativo (p ≤ 0,5). El 82% completamente satisfecho y satisfecho 18%. La altura discal aumentó 12 mm promedio (p <0,001). El movimiento del segmento afectado aumentó 4° a 7° después de la cirugía (p <0,004). Conclusión: La artroplastia lumbar de un segmento se recomienda como tratamiento eficaz para pacientes con enfermedad degenerativa discal que cumplen con los criterios de inclusión y lumbalgia sola o con componente radicular. Nivel de Evidencia III; Revisión sistemáticab de Estudios de Nível III.

Abstract Sexual shape dimorphism is the differentiation of male and female organisms based on their shape variation; this definition was proposed for the use of geometric morphometrics analysis where the geometric features of the shape are analyzed without the influence of the size. Macaria mirthae (Lepidoptera: Geometridae) is a moth that inhabits different valleys in the north of Chile principally associated to Acacia macracantha and lately Leucaena leucocephala both trees of the Fabaceae family. The Sexual dimorphism was analyzed in this species in order to corroborate studies on the use of wing as a sexual differentiation trait, and specific influence of localities was also evaluated. A clear shape variation was found where the male wings are more contracted compared to female wings. A climate influence is also suggested that could differentiate the wing shape from the individuals that inhabit two different valleys in the neotropical region of the north of Chile. This research supports previous studies identifying a clear Sexual shape dimorphism in the wing, as a selected trait, suggesting that oviposition and male competition of this group of moths is reflected in their wings. These differences raise the question whether Sexual shape dimorphism can be modulated by natural selection.

Egg laying site selection by a host plant specialist leaf miner moth at two intra-plant levels in the northern Chilean Atacama Desert. The spatial distribution of the immature stages of the leaf miner Angelabella tecomae Vargas & Parra, 2005 was determined at two intra-plant levels (shoot and leaflet) on the shrub Tecoma fulva fulva (Cav.) D. Don (Bignoniaceae) in the Azapa valley, northern Chilean Atacama Desert. An aggregated spatial pattern was detected for all the immature stages along the shoot, with an age dependent relative position: eggs and first instar larvae were clumped at apex; second, third and fourth instar larvae were mostly found at intermediate positions; meanwhile the spinning larva and pupa were clumped at basis. This pattern suggests that the females select new, actively growing leaflets for egg laying. At the leaflet level, the immature stages were found more frequently at underside. Furthermore, survivorship was higher for larvae from underside mines. All these results highlight the importance of an accurate selection of egg laying site in the life history of this highly specialized leaf miner. By contrast, eventual wrong choices in the egg laying site selection may be associated with diminished larval survivorship. The importance of the continuous availability of new plant tissue in this highly human modified arid environment is discussed in relation with the observed patterns.

The comparison of anatomical traits between organisms has been a central topic in comparative biology. Historically, taxanomic classification and biological diversity understanding have been based on morphological descriptions. Derived from a mathematical quantitative revolution, morphological studies have experienced an important renewal due to the development of shape analysis rooted in statistical multivariate methods and novel visualisation techniques. The aim of the present review is to provide an updated perspective regarding the progress in geometric morphometrics (GMM) applied to evolutionary biology, as well as introducing to cutting-edge subjects (e.g. developmental stability, modularity, morphological integration, among other themes). Thus, it is expected to provide a broad point of view with respect to the appliaction of geometric morphometrics in evolutionary biology, highlighting its usefulness as an effective, accurate, user-friendly and inexpensive method to quantify and study shape variation.

La comparación de caracteres anatómicos entre organismos ha sido un elemento central de la biología comparada. Históricamente, la clasificación taxonómica y la comprensión de la diversidad biológica se han basado en descripciones morfológicas. En base a una revolución matemática cuantitativa, el estudio de la morfología ha tenido un importante énfasis gracias al desarrollo del análisis de la forma mediante la combinación de métodos estadísticos multivariados y nuevas maneras de visualización. El objetivo de la presente revisión es dar una visión actualizada sobre los avances del estudio de la morfometría geométrica (MG) en biología evolutiva, así como introducir a temáticas en fuerte desarrollo (e.g. estabilidad del desarrollo, integración y modularidad morfológicas, entre otras). Se espera proporcionar una visión amplia del uso de la MG en biología evolutiva, destacando la necesidad de aumentar el esfuerzo de investigación en esta disciplina, junto con llamar la atención acerca de la utilidad de la MG como una herramienta efectiva, precisa, amigable y barata para cuantificar y estudiar la variación morfológica.

Some aspects of Meloidogyne spp. (root-knot nematode) growth regulation by the gram-negative bacterium Pasteuria penetrans were reviewed. The study allowed the construction of a mathematical model to predict the dynamics of both organisms. The model includes 11 differential equations and 31biological constants describing the life-cycle of the nematode and its relationship with the bacterium. To simulate the real behavior of the populations, the constants, which represent biological parameters, have to be evaluated under controlled conditions similar to those of soil microcosm.

El estudio de algunos aspectos de la regulación del crecimiento de los nematodos agalleros del género Meloidogyne Goeldi por la acción de la bacteria Pasteuria penetrans, permitió proponer un modelo matemático para predecir la dinámica de ambos organismos. El modelo incluye 11 ecuaciones diferenciales y 31 constantes biológicas que describen las fases de desarrollo del nematodo y su relación con la bacteria. Para simular el comportamiento real de las poblaciones, las constantes, que representan parámetros biológicos, deberán ser evaluadas en condiciones controladas similares a la del microcosmo del suelo.

Chiasognathus grantii, especie endémica de los bosques templados de Chile y Argentina, presenta un marcado dimorfismo sexual representado por la forma y tamaño de las mandíbulas, además de la forma del pronoto y del último segmento abdominal. Para esta especie, se han registrado además, diferencias en el tamaño de los individuos a lo largo de su distribución en Chile y parte de Argentina; ésto ha servido como evidencia para que algunos autores consideren el nombre pygmaeus', sin que esta variación haya sido evaluada cuantitativamente desde el punto de vista genético o morfológico. Este estudio evaluó cuantitativamente la variación de la forma de C. grantii según su distribución geográfica y dimorfismo sexual. Se analizaron morfométricamente 283 individuos para determinar variaciones atribuidas exclusivamente a la forma corporal, mediante registro fotográfico del área ventral de los insectos. Se obtuvo diferencias significativas interpoblacionales para la componente simétrica de la forma (variación individual) entre sexos, expresada principalmente en una expansión del tercer segmento abdominal en hembras y su retracción en machos. Sin embargo, no existe suficiente evidencia para diferenciar subespecies. Se discute si estas diferencias interpoblacionales son atribuidas sólo al dimorfismo sexual o pueden corresponder además, a presiones selectivas debido a competencia intrasexual por recursos alimenticios o debido a variaciones ambientales durante el desarrollo ontogenético.

Chiasognathus grantii, endemic species of temperate forests in Chile and Argentina, has a pronounced sexual dimorphism observed in the jaw shape and size, besides the shape of the pronotum and the last abdominal segment. Also, differences in the size of individuals have also been recorded for this species throughout its distribution in Chile and part of Argentina; this has been used as evidence for some authors to consider the name pygmaeus', although this variety has not been quantitatively assessed from the genetic or morphologic point of view. Shape variation of C. grantii was quantitatively assessed according to its geographic distribution and sexual dimorphism. A morphometric analysis was conducted on 283 individuals to determine variations exclusively attributed to body shape by means of a photographic record of the ventral area in the insect. There were significant interpopulation differences for the symmetric component of body shape (individual variation) between sex, mainly expressed as an expansion of the third abdomen segment in females and its contraction in males. However, there is not enough statistical evidence to differentiate subspecies. There is a discussion about these interpopulation differences, if they are attributed only to sexual dimorphism or if they may also be a response to selective stress due to intrasexual competition for feed resources or due to environmental variations during the ontogenetic development.

The transition from hunting and gathering to agriculture has been associated with a gracilization in human form, especially in long bones. This has been interpreted as result of an increasingly sedentary lifestyle and reduced workload in the farming populations. However the majority of these evidences have been based on the application of different biomechanical techniques or the qualitative assessment of distinct morphological traits on attachment sites. Hence, this study tried to address whether is possible to distinguish between two different populations (hunter-gatherers and farmers) by quantifying their femoral morphology applying geometric morphometrics. We compared 16 male left femora belonging to two populations of Native Americans from the same geographic region, yet temporally and behaviorally distinct, in order to test if geometric morphometrics were able to differentiate these based solely on the quantitative analysis of shape. The femora were scanned and then small portions of them were segmented in order to generate comparable 3D models. Hundred twelve equidistant landmarks were collected over the whole femoral sections and a Procrustes analysis was performed in order to obtain shape variables. Several PCAs were carried out to elucidate morphometric associations and cross-validated DAs were applied to distinguish between hunter-gatherers and farmers. These procedures were sequentially repeated using different landmarks subsets in order to try to establish the anatomical locations where bone functional adaptation mostly occurs: a) femoral cortex; b) medullary cavity; c) complete femoral section. The results here presented, showed that geometric morphometrics were able to distinguish between the two distinct lifestyles. Moreover, the contrasting results obtained from the analysis of the femoral cortex and the medullary cavity, suggest that long bone remodelling caused by lifestyle differences, mostly occurs on the outer surface of the femoral shaft. This study also showed a relative gracilization of the farmer as compared to the hunter-gatherers.

La transición desde la caza y la recolección a la agricultura ha sido asociada con una gracilización en la forma humana, especialmente en los huesos largos. Esto ha sido interpretado como resultado de un estilo de vida más sedentario y con menor carga de trabajo en las poblaciones agricultoras. Sin embargo, la mayoría de estas evidencias se han basado en técnicas biomecánicas o en la evaluación cualitativa de rasgos morfológicos en los sitios de inserción muscular. Este estudio intentó distinguir entre dos poblaciones diferentes (cazadores-recolectores y agricultores) mediante la cuantificación de su morfología femoral aplicando morfometría geométrica. Dieciséis fémures masculinos pertenecientes a dos poblaciones nativo americanas de la misma región geográfica, aunque temporal y conductualmente diferentes, fueron comparadas con la finalidad de probar si la morfometría geométrica era capaz de distinguirlas. Los fémures fueron escaneados y pequeñas porciones fueron segmentadas para generar modelos 3D. Se colectaron 112 hitos equidistantes sobre toda la superficie femoral y luego se realizó un análisis de Procusto para obtener variables de la forma. Diversos análisis de componentes principales se llevaron a cabo para establecer asociaciones morfométricas, así como también análisis discriminantes con validación cruzada para distinguir entre cazadores-recolectores y agricultores. Estos procedimientos fueron repetidos utilizando diferentes subconjuntos de hitos para establecer donde ocurre mayoritariamente la adaptación funcional del hueso: a) corteza femoral; b) cavidad medular; c) sección femoral completa. Los resultados aquí presentados mostraron que la morfometría geométrica permite distinguir entre ambos modos de vida. Además, los contrastantes resultados obtenidos del análisis de la corteza femoral y cavidad medular, sugieren que el remodelamiento óseo debido a diferentes estilos de vida ocurren mayoritariamente en la superficie de la diáfisis del fémur. Este estudio también mostró una relativa gracilización de la población agricultora al ser comparada con los cazadores-recolectores.

Latitudinal gradient effect on the wing geometry of Auca coctei (Guérin) (Lepidoptera, Nymphalidae). When the environmental conditions change locally, the organisms and populations may also change in response to the selection pressure, so that the development of individuals may become affected in different degrees. There have been only a few studies in which the patterns of wing morphology variation have been looked into along a latitudinal gradient by means of geometric morphometrics. The aim of this work was to assess the morphologic differentiation of wing among butterfly populations of the species Auca coctei. For this purpose, 9 sampling locations were used which are representative of the distribution range of the butterfly and cover a wide latitudinal range in Chile. The wing morphology was studied in a total of 202 specimens of A. coctei (150 males and 52 females), based on digitization of 17 morphologic landmarks. The results show variation of wing shape in both sexes; however, for the centroid size there was significant variation only in females. Females show smaller centroid size at higher latitudes, therefore in this study the Bergmann reverse rule is confirmed for females of A. coctei. Our study extends morphologic projections with latitude, suggesting that wing variation is an environmental response from diverse origins and may influence different characteristics of the life history of a butterfly.

O número de ínstares sugadores do minador de folhas Angelabella tecomae Vargas & Parra, 2005 foi determinado mediante a coleta de exúvias de cápsulas cefálicas de larvas sugadoras em minas (n = 125) do arbusto Tecoma fulva fulva D. Don (Bignoniaceae), no vale de Azapa, norte do Chile. A larva passou por quatro ínstares em 120 ocasiões, e por cinco ínstares, em outras cinco. As possíveis causas da variação e a utilidade da ferramenta para futuros estudos são discutidos.

The number of sap-feeding instars of the leaf-miner Angelabella tecomae Vargas & Parra, 2005 was determined by measuring the head capsule exuviae collected from mines (n = 125) on the shrub Tecoma fulva fulva D. Don (Bignoniaceae) in the Azapa Valley, northern Chile. Sap-feeding larvae went through four instars in 120 occasions while five larvae went through five instars. The possible causes for this variation and the usefulness of this tool for future studies are discussed.

Variations can be observed in pollinator assemblages of exotic species in response to changes in environment or to variables that did not receive much attention. This paper is the first approximation of the abundance of pollinator species associated with Eucalyptus nitens in a Clonal seed-bank plantation (CSBP) of the farm "Rucamanqui", Huepil, Biobío Region in Chile. Between October and November 2010, we examined the variation of pollinator's entomofauna of E. nitens. Environmental factors, such as temperature and the number of open flowers per plant, were registered to determine the level of dependence on the frequency of visits. The most abundant insects visiting E. nitens belonged to the orders Coleoptera, Hymenoptera, Diptera and Lepidoptera. However, the proportion of individuals in each group of flower visitors varied considerably among the sampling months: Hymenoptera (203), Coleoptera (21) in October and Coleoptera (280), Hymenoptera (57) in November. For Hymenoptera, environmental temperature was significant compared to frequency of visitors; whereas for Coleoptera, the number of open flowers per plant has been significant for insect activity. Results show that the visit frequency of pollinators in E. nitens is highly variable within the sampling period and temperature and density of open flowers per plant can produce variations within the group of pollinators.

Las variaciones que se pueden observar en los ensambles de polinizadores de especies exóticas, en respuesta a cambios en las variables ambientales o florales, no han recibido mucha atención. Este trabajo constituye la primera aproximación sobre la abundancia de especies polinizadoras, asociadas al Eucalyptus nitens en un huerto semillero clonal de la hacienda Rucamanqui, localidad de Huépil (37º 15' S y 71º 55' O), región del Biobío. Entre octubre y noviembre de 2010, se examinó la variación de la entomofauna polinizadora de E. nitens. Se registraron además factores como la temperatura ambiental y el número de flores abiertas por planta para determinar el nivel de dependencia de la frecuencia de visitas. Los insectos más abundantes que visitaron a E. nitens pertenecen a los órdenes Coleoptera, Hymenoptera, Diptera y Lepidoptera. Sin embargo, la proporción del total de los individuos visitantes florales en cada uno de los grupos varió notablemente entre los meses de muestreo: Hymenoptera (203), Coleoptera (21) en octubre, y Coleoptera (280), Hymenoptera (57) en noviembre. Para Hymenoptera la temperatura ambiental fue significativa frente a la frecuencia de visitas y para Coleoptera el número de flores abiertas por planta fue significativo frente a la actividad de los insectos. Los resultados muestran que sobre E. nitens la frecuencia de visita de polinizadores es altamente variable dentro del período de muestreo y que la temperatura y la densidad de flores abiertas por planta pueden generar variación dentro de cada grupo de polinizadores.