Revista de Biología Tropical Vol.50 (2)
https://hdl.handle.net/10669/15283
2024-03-28T15:10:56ZBosque y Población en la Península de Osa, Costa Rica
https://hdl.handle.net/10669/15462
Bosque y Población en la Península de Osa, Costa Rica
Este estudio relaciona datos geocodificados de censos de población con información de uso de la tierra proveniente de imágenes de satélite y fotografías aéreas. Se analizan tres procesos: deforestación, reforestación y fragmentación en el período 1980 - 1995 y se identifican relaciones con potenciales de población derivados del censo de 1984, en las que se controlan efectos de terceras variables como caminos, lluvias, distancia al borde de bosque, grado de protección, etc. Entre 1980 y 1995 se taló el 16% del bosque, se fraccionó un 3% adicional y se reforestó el 32% del área en pastos o cultivos. Se identificaron fuertes y significativas asociaciones entre potencial de población en 1984 y los procesos de deforestación, reforestación y fragmentación. La probabilidad de deforestación es nula en áreas despobladas y llega a 54% en bosques con 75 o más hogares potenciales. La regresión múltiple muestra elasticidades del número de hogares de 0.63 en el riesgo de deforestación, de -0.37% en los de reforestación y de 1% en los de fragmentación. Se valora el riesgo de deforestación en 1995 - 2010 y se identifican las zonas geográficas con riesgo de perder el bosque por presión poblacional. Estas áreas incluyen la mayoría de bosques que no son parte del Parque Nacional Corcovado (especialmente la cuenca del río Rincón) y representan casi la mitad del bosque actual de la Península.; The research is focused on the relationship between population growth and conservation of the forest on the Osa Peninsula. Data of the georeferenced censuses and information on land-use, derived from satellite images and aerial photography, were integrated into a GIS. We undertook an historical inventory of the changes in the population and the forest coverage, and the key events in the land tenure and economy of the region. Deforestation, reforestation, and fragmentation of the forest during the period 1980 - 1995 were analyzed. Relationships with the population potential, derived from the 1984 Costa Rican censuses, were identified, and the effects of third variables were controlled such as distances to the roads, rain, distances to the forest frontier, level of protection, etc. Both strong and significant associations between 1984 population potential and the three processes were detected. The probability of deforestation is null in unpopulated areas, 35% in areas with 25 - 30 potential farmers and to 65% in areas with 50 farmers and over. The probability of reforestation decreases from 100% to 28% and to 18% in these three categories. This kind of relationship persists in the multivariable analysis. An increase of 0.63% in the number of household, results in an increment of 1% in the risk of deforestation (elasticity). The elasticity in the chances of reforestation is -0.37 and 1% in fragmentation of the forest. An evaluation in the risk of deforestation for the period 1995 - 2005 was done. The most recent population data were used and it identifies several geographic areas with high deforestation risk.
artículo -- Universidad de Costa Rica. Instituto de investigaciones en Salud, 2002
2002-01-01T00:00:00ZDoes a polyphagous caterpillar have the same gut microbiota when feeding on different species of food plants?
https://hdl.handle.net/10669/15284
Does a polyphagous caterpillar have the same gut microbiota when feeding on different species of food plants?
We used classical culture techniques to explore gut bacteria and changes associated with dietary change in the highly polyphagous, tropical caterpillar Automeris zugana(Saturniidae). Fifty-five third instar wild-caught sibs feeding on Annona purpurea(Annonaceae) in the Área de Conservación Guanacaste (ACG) in northwestern Costa Rica were divided into eight groups. Each of seven groups was reared to the ultimate instar on another species of food plant normally used by A. zugana. Some pupae were also analyzed for the presence of bacteria. Aerobic bacterial cultures were obtained from all 33 caterpillar guts and the eight pupae inventoried. There was no clear pattern in species composition of cultivated bacteria among the eight diets, and each caterpillar on a given food plant carried only a small fraction of the total set of species isolated from the set of caterpillars feeding on that food plant. Taken as a whole, the larvae and pupae contained 22 species of cultivable bacteria in 12 genera. Enterobacter, present in 81.8% of the samples, was the genus most frequently isolated from the caterpillars, followed by Micrococcusand Bacillus. Bacillus thuringiensiswas isolated from 30.3% of the
dissected caterpillars, but found in caterpillars feeding on only half of the species of food plants.; Usamos técnicas de cultivo clásicas para explorar las bacterias del intestino y los cambios asociados con el cambio dietético en la, altamente polífaga, oruga tropical Automeris zugana (Saturniidae). Se capturaron 55 individuos hermanos, silvestres, de tercer estadio, alimentándose de Annona purpurea(Annonaceae) en el Área de Conservación Guanacaste (ACG) en el noroeste de Costa Rica y se
dividieron en ocho grupos. Siete grupos fueron criados hasta el último estadio en otra especie de planta a la normalmente usada por A. zugana. Algunas pupas también fueron analizadas para ver la presencia de bacterias. Se obtuvieron cultivos de bacterias aeróbicas de los 33 intestinos de las orugas y de las ocho pupas muestreadas. No hubo un patrón claro en la composición de especies de las
bacterias cultivadas entre las ocho dietas y cada oruga en una planta dada representó solo una pequeña fracción del conjunto total de especies aisladas de orugas alimentándose de esa planta. Tomándolas como un solo grupo, las larvas y pupas tuvieron 22 especies de bacterias cultivables en 12 géneros. Enterobacter, presente en 81.8% de las muestras, fue el género aislado de las orugas con más frecuencia, seguido por Micrococcusy Bacillus. Bacillus thuringiensisfue aislado de 30.3% de las orugas disectadas, pero encontrado en orugas alimentándose de solo la mitad de las especies de plantas.
artículo -- Universidad de Costa Rica. Centro de Investigación en Biología Molecular, 2002
2002-01-01T00:00:00ZDaño del ADN en trabajadoras bananeras expuestas a plaguicidas en Limón, Costa Rica
https://hdl.handle.net/10669/11329
Daño del ADN en trabajadoras bananeras expuestas a plaguicidas en Limón, Costa Rica
Pesticide use in Costa Rica is very high and all year round. A high percentage of what is sprayed
remains in the environment and in the living organisms around. This situation brings contamination and health
problems to people in contact with them. The onset of adverse effects may be in the short or the long term, and
symptoms vary widely, from headaches to cancer. Much research in this area has been devoted to acute or chronic
effects, and not until recently to the genotoxic effect of pesticides. This study evaluated the genotoxic effect
of pesticides used in banana packing activities, using the comet assay (single cell electrophoresis) as the biological
marker in lymphocytes. This was a case-control double blind study of 30 exposed women from 15
banana farms and 28 women not occupationally exposed to pesticides from the same geographic area. Results
show damage to single stranded DNA after working from 5 to 15 years (R2=0.12). In Costa Rica we do not have
an historical record of the kind of pesticides used in banana farms, the period of time and for how long were they
used. This prevented further analysis concerning dose, frequency of exposure and use of new or old kind of pesticides
in the farms in relation to DNA damage. The comet assay is of value in the genetic monitoring of pesticide
exposed populations
Artículo científico -- Universidad de Costa Rica. Instituto de Investigaciones en Salud, 2002
2002-06-01T00:00:00ZComprendiendo los venenos de serpientes: 50 años de investigaciones en América Latina
https://hdl.handle.net/10669/11075
Comprendiendo los venenos de serpientes: 50 años de investigaciones en América Latina
As a tribute to Revista de Biología Tropical in its 50th anniversary, this review describes some of the main research efforts carried out in the study of the chemical composition and the mechanism of action of toxins present in the venoms of snakes distributed in Latin America. Venom proteins involved in neurotoxicity, coagulopathies, hemorrhage and muscle necrosis are discussed, together with a description of the inflammatory
reactions elicited by these venoms and toxins. In addition, the search for inhibitory substances present in plants and animals that may be utilized in the neutralization of venoms is analyzed. Some of the clinical studies performed on snakebite envenomations in Latin America are also reviewed, together with the development of technologies aimed at improving the quality of antivenoms produced in the region. Toxinology has become a fruitful and stimulating research field in Latin America which has contibuted to a better understanding of snake venoms as well as to an improved management of snakebitten patients.
artícculo (arbitrado) -- Universidad de Costa Rica, Instituto de Investigaciones Clodomiro Picado, 2002
2002-01-01T00:00:00Z