Theses & Dissertations

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https://hdl.handle.net/20.500.11801/5
This collection is exclusively made up of theses, dissertations, and project reports submitted as a requirement for completing a graduate degree at UPR-Mayagüez. If you are a UPRM graduate student and you are looking for information related to the deposit process, please refer to https://libguides.uprm.edu/repositorioUPRM/tesis

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  • Publication
    Biosystematic analysis of Adiantum vivesii Proctor (Polypodaceae: Adianthoideae), a rare fern endemic to northwestern Puerto Rico
    ( 2000) Sepúlveda Orengo, Marian T. ; Kolterman, Duane A. ; College of Arts and Sciences - Sciences ; Sastre De Jesús, Inés ; Breckon, Gary J. ; Department of Biology ; González Miranda, Sally
    Adiantum vivesii Proctor is a rare fern endemic to the northwestern part of Puerto Rico, known only from its type locality on limestone substrate on privately owned land in the Municipality of Quebradillas. The distribution, abundance, morphology, and cytology of the species were studied to clarify its status as a distinct species or of hybrid or polyploid origen. The population of A. vivesii occupies a total area of 21 m x 10 m; eight sympatric species of Adiantum are found in the immediate area. Following several deep excavations it was concluded that the entire population of A. vivesii is one individual with proliferation by rhizomes. Morphological measurements and light and scanning microscopy were used to describe some parts of A. vivesii and A. tetraphyllum. Morphometric studies were conducted for 22 characters of the species and the possible parent, Adiantum tetraphyllum. Greater variability was obtained within the A. tetraphyllum population, and statistically significant differences between the two species were observed for 17 characteristics. Meiotic studies were inconclusive, but no evident difference in chromosome number was observed between the two species. The spores of A. tetraphyllum showed normal appearance and were rarely abortive, while those of A. vivesii showed greater variability in size and were almost always abortive, suggesting that A. vivesii is a sterile hybrid.
  • Publication
    Wedelia trilobata (L.) Hitchc. (Asteraceae) como repelente de Bemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae) y de Cosmopolites sordidus Germar (Coleoptera: Curculionidae)
    ( 2001) Ramos Rodríguez, Olgaly ; Mari Mutt, José A. ; College of Arts and Sciences - Sciences ; Pantoja, Alberto ; Acosta, Jaime A. ; Department of Biology ; González, Ángel
    Laboratory experiments were conducted to understand the influence of Wedelia trilobata (L.) Hitchc. on the oviposition of Bemisia argentifolii Bellows & Perring over tomato leaves and on the presence of Cosmopolites sordidus Germar over plantain pseudostems. Solutions made with aqueous extracts of W. trilobata (100, 75, 50, 25 and 0 %) were applied to plants exposed to these insects. The extracts repelled adults of C. sordidus when applied to pieces of plantain pseudostem, but did not affect the oviposition rate of B. argentifolii when applied to tomato leaves. Field experiments using sticky traps compared whitefly abundance in plots surrounded by W. trilobata and control plots (without wedelia). No significant differences were obtained between treatments. Wedelia had no effect on whitefly abundance under field conditions.
  • Publication
    Population ecology and reproductive behavior of the endangered Buxus vahlii Baillon (Buxaceae)
    ( 2001) Carrero-Rivera, Gloryvee ; Kolterman, Duane A. ; College of Arts and Sciences - Sciences ; Lewis, Allen ; Silander, Susan ; Department of Biology ; González Lagoa, Juan G.
    Buxus vahlii Baillon is an endangered plant species endemic to Puerto Rico and St. Croix (USVI). There are six known populations, four in Puerto Rico (Rincón, Isabela, two in Bayamón) and two in St. Croix (Frederiksted and Christiansted). The status of these populations was studied to provide information on the ecology of the species. The species showed the ability to adapt to different environmental conditions. Such adaptations include shrubby growth in dry areas where it grows as part of the understory (Rincón, Frederiksted and Christiansted) vs. an arborescent growth form in high precipitation areas (Isabela and Bayamón). Identified human impacts on the studied populations were: development (Frederiksted), illegal immigrants and fires (Rincón), and rock climbing and introduced species (Bayamón). The Isabela and Christiansted populations were not impacted due to their low accessibility. Actualization of the management plan is suggested to reverse the decline of this species and restore the populations.
  • Publication
    Bacterias asociadas al cultivo del plátano (Musa sp.) y su relación con el aborto del racimo
    ( 2003) Rengifo-Medina, Judith ; Zapata-Serrano, Mildred ; College of Agricultural Sciences ; Diaz, Manuel ; Inglés, Rafael ; Muñoz, Carlos A. ; Department of Crops and Agro-Environmental Sciences ; Inglés, Rafael
    Plantain production (Musa spp.) in Central, South America and the Caribbean is limited by bacterial diseases. In Puerto Rico, the production of the plantain “Hua Moa” is affected by a disease called bunch abortion or choke neck. Although it is common to observe soft rot tissue suggesting interactions with biotic agents, no research has been conducted to explain the disease in terms of abiotic or biotic agents. This study tried to identify bacteria and their role in relation to the choke neck disease. Bacteria were isolated from pseudostems of “Hua Moa” in three locations in Puerto Rico, using common and semi-selective growth media. Pathogenicity was determined using potato and plantain pseudostem discs in humid chambers under in vitro conditions. Under greenhouse conditions the pathogenicity of four bacteria were tested on whole plants on the clones Maricongo, Grand nain, Enano, FHIA-01 and “Hua Moa”. A field experiment was conducted during 10 months on “Hua Moa” plants inoculated with Pseudomonas aeuriginosa. A total of 167 strains were isolated from diseased plants from which Burkholderia gladioli, Erwinia chrysanthemi and P. aeuriginosa were determined pathogenic. E. chrysanthemi was virulent in all clones tested under greenhouse conditions. Significant differences between treatments were not found under field conditions suggesting that P. aeuriginosa have no relation with the disease. At the other hand, E. chrysanthemi may be responsible of the soft rots developed on “Hua Moa” plantain once the choke neck disease is initiated.
  • Publication
    Interactive weather station data display through the internet
    ( 2003) Espaillat-Valcárcel, Francisco J. ; Vásquez-Espinosa, Ramón ; College of Engineering ; Winter, Amos ; Rodríguez, Néstor ; Department of Electrical and Computer Engineering ; Gamess, Eric
    The study of weather phenomena is of growing importance. Changes in the overall conditions of the world, such as global warming, ozone depletion, and the uncertainty on the causes of these events, has made weather research more important than ever. To study these phenomena, researchers rely on archived weather data. Which are usually found by request at institutions that operate weather stations. The researcher’s analysis is facilitated if stored in electronic form, such as computer documents or spreadsheets. The structure, and format of the data, along with the capacity to manipulate and display it in a user-friendly interface will greatly enhance the researcher’s study of the climate data. Here I present an application for obtaining and displaying weather data on the Internet, a database system that allows the retrieval of data by other organizations, and proposed data structures to be adopted for the sharing of this type of data.
  • Publication
    Desarrollo de un sistema middleware para sensores remotos con fuente de datos distribuida
    ( 2003) Alvear-Suárez, Alcides ; Rodríguez-Martínez, Manuel ; College of Engineering ; Couvertier, Isidoro ; Rivera, Wilson ; Rivera, Pedro I. ; Department of Electrical and Computer Engineering ; Bollman, Dorothy
    This thesis describes the tool ImageCutter, which does part of the megaproject TerraScope. The effected design uses a system middleware for, across the Internet, to connect a set of computers creating a virtual computer of great coverage, capable to handle information related to hyperspectral images. The provided information, as well as the resources of calculation, they can be located physically in diverse sites. These resources include components both of hardware and of software (ej. Matlab, Java and final user of applications). The system ImageCutter allows the processing image of distributed form and realizes the division of images of agreement to the specifications of the user. Tried the image, this ImageCutter in capacity of: to recover the information, to gather the new byline and to offer new forms of interpretation to the client. The architecture of the component ImageCutter and the algorithms used for the design of the tool will be discussed in the theoretical and methodological foundation of the thesis.
  • Publication
    Xroaster: a tool for catalog management on databases middleware systems
    ( 2003) Molina-Vargas, Ana M. ; Rodríguez-Martínez, Manuel ; College of Engineering ; Vélez, Bienvenido ; Rodríguez Rivera, Néstor ; Department of Electrical and Computer Engineering ; Castillo, Paul
    Currently there are very few tools available for managing the catalog of a Database Middleware System. The system administrators of the Middleware System need to manually add all the metadata necessary to configure and maintain the catalog, making catalog maintenance a tedious task. In this thesis we present XRoaster, a visual tool to perform catalog management tasks in Database Middleware Systems. XRoaster is designed to generate its results in XML documents that contain metadata about the data sources. This makes it possible to easily share system metadata with other applications. XRoaster is a graphical, user friendly tool and that follows the rules of usability for the creation of Graphical Interfaces. One of the major features of XRoaster is its ability to guide the end-user in the administrative tasks: adding users, implementing global schemas, adding new sources of data, defining the required schema mapping rules. We argue that XRoaster provides a very robust framework for catalog management.
  • Publication
    Brioflora sobre taludes del transecto Mayagüez-Maricao (Puerto Rico)
    ( 2003) Narváez Parra, Eliana X. ; Kolterman, Duane A. ; College of Arts and Sciences - Sciences ; Lewis, Allen R. ; Torres, Ramón I. ; Department of Biology ; Torre, Winston de la
    The bryoflora was determined on roadside banks along the transect Mayagüez-Maricao that begins in the municipality of Mayagüez at an elevation of 15 m on highway 108 and culminates in the municipality of Maricao on highway 120 South at an elevation of 472 m. During the months of February to April of 2003 an ecological inventory was carried out at five sampling stations of 10 m2 each, in which 3 m2 were chosen at random to collect the bryophyte species and to determine cover. In the month of May of the same year a floristic inventory was carried out at 13 sampling stations along the studied transect. Analysis of similarity among the stations, variance, distribution and association among species were analyzed. Dicranella hilariana, Fossombronia brasiliensis, Lejeunea cladogyna and Philonotis uncinata were the most frequent species and those with wide distribution on the highway banks.
  • Publication
    Tunable slot-ring antenna using varactors
    ( 2003) Carrasquillo-Rivera, Ileana ; Rodríguez-Solís, Rafael A. ; College of Engineering ; Colom Ustariz, José ; Cruz Pol, Sandra ; Department of Electrical and Computer Engineering ; Vásquez, Pedro
    A dual mode rectangular slot-ring antenna fed with a coplanar waveguide transmission line was tuned over a band of frequencies using varactors. The analysis demonstrated that when varactors are attached to the side slots of the 2.4-GHz rectangular slot-ring antenna, the second resonant frequency could be tuned over a 22 % bandwidth around 3.7 GHz while the first resonance remains unchanged. The first resonant frequency could be tuned over a 4.4 % bandwidth around 2.25 GHz when varactors were connected across the bottom slot. Consequently, varactors were placed across both side slots and across the bottom slot on the same antenna configuration. Results showed that both frequencies could be independently tuned when both sets of varactors are separately biased. A 7.3 % frequency shift around 2.18 GHz and a 12.3 % frequency shift around 4.05 GHz were registered. Agreements between simulations and prototypes results were achieved.
  • Publication
    Contribution of picoplankton to phytoplankton dynamics and bio-optics of the eastern Caribbean sea
    ( 2003) Lee-Borges, Jesús ; Armstrong, Roy A. ; College of Arts and Sciences - Sciences ; Gilbes, Fernando ; López, José ; Planas, José ; Aponte, Nilda E. ; Department of Marine Sciences ; Montalvo, Rafael
    The picoplankton contribution to the total biomass has not been considered when it is estimated using remote sensors. In this work, In situ chlorophyll-a values were compared to values obtained from; a) Sea-viewing Wide Field-of-view Sensor (SeaWiFS) imagery, and b) different algorithms (calculated with data from a spectroradiometer) for the Caribbean Time Series Station (CaTS) from October 1997 to August 2002. Regression analysis suggests that the Moderate-resolution Imaging Spectroradiometer (MODIS) algorithm provided the best estimate of the in situ chlorophyll-a value (r2=0.67089). The SeaWiFS OC-4v4 algorithm overestimated chlorophyll-a values when the in situ value was <0.2 μg/L and underestimate it when the in situ value was >0.2 μg/L. This is due to sampling error resulting from the use of 0.7 μm GF/F filters. Picoplankton loss through 0.7 μm filters (Whatman GF/F) compared to 0.2 μm membrane filters (Millipore TCMF) was quantified for oceanic stations of the North Eastern Caribbean Basin and Mayagüez Bay. On average, a 20% loss of picoplankton in oceanic stations, and a 9% loss for coastal stations were observed Size fractionated phytoplankton analysis revealed that picoplankton was the dominant size class in oceanic stations (accounting for 60-85% of the total phytoplankton biomass and 61-77% of the absorption of light by particulates), while larger phytoplankton (>2.0 μm) dominate coastal stations. Temporal and spatial variability was observed in the size distribution of the phytoplankton community in all the stations. Electrophoretic patterns of Restriction Fragment Length Polymorphism (RFLP) corroborated the variability. These results emphasize the importance of picoplankton variability when temporal and spatial scales are considered, and suggests that this group of photoautotrophs, rather than simply representing a “background noise”, constitutes an active and changing component of the microbial community in the open ocean and even in productive waters. To improve satellite estimates of phytoplankton biomass, future algorithms must take into account the contribution of the picoplankton to the phytoplankton population.
  • Publication
    Relación hospedero Parasitoide y dinámica poblacional de los parasitoides de las masas de huevos de Diaprepes Abbreviatus (L.) (Coleoptera : Curculionidae) en Puerto Rico
    ( 2003) Vargas-Cruzado, Edgardo ; Franqui-Rivera, Rosa A. ; College of Agricultural Sciences ; Abreu Rodríguez, Edwin ; Medina Gaud, Silverio ; Department of Crops and Agro-Environmental Sciences ; Mari Mutt, José A.
    A study was done at Adjuntas and Isabela with the purpose of identifying the parasitoid species associated with the eggs mass of the sugarcane weevil. Four species of parasitoids were found, three in the family Eulophidae and one the family Trichogrammatidae. The eulophid species were Tetrastichus haitiensis, Aprostocetus gala and Horismenus bennetti and Brachyufens osborni in the Trichogrammatidae. It was found that the months with the higher incidence of parasites were June and July. Tetrastichus haitiensis was selected for the study of host-parasitoid relation. The preference of this parasitoid for the age and size of the eggs mass of the sugarcane weevil was determined. The parasitoid wasps prefer 12 hours eggs, when compared with 24, 48 and 72 hours; for the size of the eggs mass the parasitoid prefers 71-107 eggs per mass. Also the preference of the sugarcane weevil for oviposition was studied in four hosts (yam, sweet potato, orange, pigeon pea). The oviposition was higher in the yams and sweet potato leaves.
  • Publication
    Solubilities of anti-cancer and anti-AIDS drugs in supercritical carbon dioxide
    ( 2003) Pulido-Ayazo, Juan C. ; Suleiman-Rosado, David ; College of Engineering ; Romañach, Rodolfo ; Velázquez Figueroa, Carlos ; Department of Chemical Engineering ; Rivera, Luis
    Solubility data for pharmacological drugs in supercritical fluids (SCFs) is of great importance, because there is an environmental and cost effective need for alternative specialty separation methods. This research was focused on the study and determination of solubilities of some anticancer (e.g., Taxol, 5-Fluorouracil) and anti-aids drugs (e.g., Azodicarbonamide, Thymidine and 2-Phenyl-4H-3,1-benzoxazin-4-one) in supercritical carbon dioxide. These measurements were made using a Supercritical Fluid Chromatograph (SFC) coupled to a high pressure UV detector online. The solubility of these drugs were studied as a function of temperature (35.1°C ñ 55.1°C) and pressure (100 ñ 300 bar). This technique was initially validated using phenanthrene and compared with the data of several other investigators. The technique proved to be fast, reliable and reproducible. The order of magnitude of the obtained solubilities was 10-6 to 10-4 mole fraction. The drug with the highest solubility was 2-Phenyl-4H-3,1-benzoxazin4-one and the less soluble was taxol. These results correlated well with the volatility of the drugs (indicated by their melting point). This research also studied the effect of pressure (100 ñ 300 bar) and temperature (35.1°C ñ 55.1°C) on the solubility of the drugs. The effect of pressure on the solubility of the drugs followed the expected trend of increasing solubility with an isothermal increase in the pressure for all temperatures studied. This is explained since as pressure is increased, carbon dioxide density increases, and the intermolecular mean distance of carbon dioxide molecules decreases; thereby, increasing the specific interaction between the solute and solvent molecules. The temperature effect always showed a proportional effect in solubility. This indicated that the temperature effect in solute volatility (proportional effect) was more significant than the temperature effect in solvent density (inversely proportional effect). This study showed that it is possible to determine relatively fast a large number of solubility measurements for the studied systems by retention in SFC.
  • Publication
    Charting the route: From gothic to magic realism
    ( 2003) Ríos Cordero, Hugo ; Batra, Nandita ; College of Arts and Sciences - Art ; Leonard, Mary ; Irizarry, José M. ; Department of English ; Orlandini, Roberta
    Gothic fiction is one of the most interesting and influential forms of literature. Its scope has reached many genres, periods and epochs, and it has engendered numerous offspring since its origin. One of its most famous progenies is Magic Realism. This study traces the history of Gothic conventions since their origins in eighteenth-century literature, through the modifications they underwent in the nineteenth century and the eventual transformation into the codes that correspond to Magic Realism. Chapter One recounts the origin of Gothic Literature based on the analysis of the conventions that define it as a genre. Chapters Two and Three trace the development of these Gothic conventions by studying some examples of the next generation of Gothic novels: Mary Shelley’s Frankenstein and Robert Louis Stevenson’s The Strange Case of Dr. Jekyll and Mr. Hyde. Chapter Four introduces a brief history of Magic Realism and explores the relationship of this mode with the Gothic. Finally, Chapter Five presents an analysis of Salman Rushdie’s Shame, a novel that illustrates the evolution of Gothic conventions and the way in which they became part of the accepted codes of Magic Realism.
  • Publication
    Stellar imaging interferometry
    ( 2003) Yance-Orcasita, Armando De J. ; Chang, Mark J.L. ; College of Arts and Science - Science ; Jiménez, Héctor ; Pabón-Ortiz, Carlos U. ; Department of Physics ; Gooransarab, Haedeh
    This thesis work, developed at the laboratories of the Department of Physics of the University of Puerto Rico, reports the first efforts to build a prototype stellar interferometer with applications to stellar astrophysics. The work is focused in the automation of the key subsystems in the interferometer: the Optical Delay Lines (ODLs). The automation of the mechanical controls that allows displacement of ODL, is achieved through the use of inexpensively built stepper motors and driver cards, using slave processors and implementing control through their parallel ports. Our Objective was to obtain precision displacement of the system that controls the ODL. We found that the motors were able to move 400 nm per step in one direction; with a maximum error of 0.5%, but bidirectional motion has a much larger error in our implementation of the system. In testing the prototype while studying the visibility of the fringes, I found that the polarization effects due to the reflections away from normal incidence are an important factor for the optical design of the interferometer.
  • Publication
    Determinación de digestibilidad y consumo de materia seca de Heno de Arachis glabrata en rumiantes
    ( 2003) Rivera-Estremera, Loures ; Ruiz-López, Teodoro M. ; College of Agricultural Sciences ; Randel, Paul F. ; Macchiavelli, Raúl ; Latorre, José R. ; Department of Animal Science ; Borges, Sonia
    The experiment was conducted to determine the digestibility of hays from two accessions of rhizoma peanut (RP;17033 and 17097) and from Bermuda grass (B) as determined by the total collection method (in vivo), with nine mixed-breed lambs randomly allotted to treatments in a 3 x 3 latin square design with three repetitions. Also, the three methods for determining forage digestibility (in vivo, in vitro and in situ) were compared. Estimates of in vitro digestibility were obtained using a Daisy II incubator (48 hours). In addition, in situ digestibility using dacron bags placed (48 hours) inside the rumen of a fistulated cow fed grass hay was determined. Daily intake of dry matter (DM), organic matter (OM) and acid detergent fiber (ADF) were similar for both RP accessions and were higher (P<0.05) than B, 1.02 vs. .7442 kg/d, .9185 vs. .6782 kg/d and .3764 vs. .2774 kg/d, respectively. In vivo DM, OM, crude protein (CP), and ADF digestibility and digestible energy (DE) of both RP accessions were higher (P<0.05) than those of B. Small, but significant differences were found between the two RP accessions in favor of 17097 in digestibility of DM, OM, and neutral detergent fiber (NDF) and in favor of 17033 in CP digestibility and DE. In vivo ADF digestibility did not differ (P>0.05) between the RP accessions. In vitro and in situ DM and NDF digestibility were higher (P<0.05) for the two RP combined as compared to B (in vitro, 66.83 vs. 44.74 % e in situ, 71.63 vs. 48.12 % of DM; in vitro, 42.21 vs. 30.01 %, e in situ, 42.25 vs. 25.14 % of NDF, respectively). However, both in vitro and in situ OM digestibility differed (P<0.05) among all three hays, being greatest for RP 17033 (65.21 %). Both in vitro and in situ methods overestimated in vivo DM and OM digestibility of both RP accessions and underestimated those of B. In vivo NDF digestibility of both RP was underestimated by both in vitro and in situ methods. According to the results, the in situ method gave the best estimates of in vivo digestibility. Because of its high voluntary intake and digestibility, as determined by three methods (in vivo, in situ and in vitro), the RP demonstrated its outstanding quality potential.
  • Publication
    Improved gray-box modeling of electric drives using neural networks
    ( 2003) Báez-Rivera, Yamilka I. ; Vélez-Reyes, Miguel ; College of Engineering ; Hunt, Shawn D. ; Venkatesan, Krishnaswami ; Department of Electrical and Computer Engineering ; Orama Exclusa, Lionel R.
    Electric drives are used in many industrial and commercial applications. High performance control of electric drives requires the accurate modeling of the motor and mechanical load. In many industrial applications, it is desirable that the electric drive has the capability of self-tuning controller parameters to be able to drive different mechanical loads. One way to achieve this flexibility is by direct identification of the drive and mechanical load. Modeling and identification of Electric drive coupled to a load can be a challenging task. This research investigates the use of gray box models to identify electric drive systems connected to an unknown load. In the proposed model, the electrical subsystem of the machine is modeled using physical principles while the mechanical subsystem is modeled using a black box model based on neural networks. A two-stage identification approach that separates electrical subsystem parameter estimation from mechanical subsystem identification is presented. At each stage the parameters are estimated using the linear least squares approach. Simulation results are presented to demonstrate the feasibility of the approach.
  • Publication
    Genetic algorithm approach for reorder cycle time determination in multi-stage systems
    ( 2003) Romero-Encarnación, Heidi L. ; Cesaní-Vázquez, Viviana I. ; College of Engineering ; Bartolomei Suárez, Sonia M. ; Hernández Rivera, William ; Department of Industrial Engineering ; Seguí Figueroa, Miguel A.
    The objective of this research is to provide a genetic algorithm to determine the reorder cycle time for multi-stage serial and assembly systems. Demand for end item is assumed to occur at a constant and continuous rate. Production is instantaneous and no backorders are allowed. Both setup and echelon holding costs are charged at each stage. The attention is on nested and stationary policies. Furthermore, the reorder interval for each echelon is restricted to be not only integer, but also a power of two times a base planning period. The performance of the genetic algorithm is evaluated in comparison with an optimal approach proposed by Maxwell and Muckstadt (1985), obtaining solutions from zero to five percent from the optimum for small problems. Experimentation is conducted to determine the genetic algorithm parameters and in addition to evaluate the robustness of the proposed methodology.
  • Publication
    Dinámica poblacional de Spoladea recurvalis (F.) (Lepidoptera: pyralidae) y sus relaciones tritróficas con variaciones en la densidad poblacional de la peseta, Trianthema portulacastrum (L.).
    ( 2003) Figueroa-Pérez, Lorimar ; González-Rodríguez, Ángel L. ; College of Agricultural Sciences ; González, Lizzette ; Semidey, Nelson ; Department of Crops and Agro-Environmental Sciences ; Berríos, Ángel
    The weed “horse purslane” (Trianthema portulacastrum [L.]) may be completely defoliated by Spoladea recurvalis (F.) larva, but the lack of a temporal synchrony between them precludes that the competition exerted by the weed on vegetable crops is avoided. In field studies (2001-02) with varying densities of the weed conducted in the Agricultural Experiment Station in Juana Díaz and in studies in fallow plots located in Juana Diaz, Santa Isabel and Lajas, it was found that the population densities of S. recurvalis were directly related to the population density of the weed. The herbivore reached regulating densities when the weed attained almost a hundred percent ground coverage. Applications of Bt-based products reduced S. recurvalis larval densities, however, the reduction in larval densities did not preclude the eventual defoliation of the weed. The insect is present, with an aggregated distribution, throughout the year in the localities studied. In choice tests, larvae preferred to feed on “horse purslane” than on other weeds and did not feed on crops, except for sugar beet. The following hymenopterans parasitoids were identified attacking S. recurvalis: the braconids Apanteles sp., Cremnops sp. and Chelonus cautus Cresson, and the pteromalid Catolaccus sp. The chalcidid Spilochalcis sp. and the elasmid Elasmus sp. were found as hyperparasites of Apanteles.
  • Publication
    Consumo voluntario y digestibilidad de nutrientes de heno de gramíneas tropicales nativas y ensilaje de sorgo y el efecto de la suplementación con residuos fermentados de pescadería
    ( 2003) León-Álamo, Felix J. ; Rodríguez-Carías, Abner A. ; College of Agricultural Sciences ; Randel, Paul F. ; Ruiz, Teodoro ; Latorre, José R. ; Department of Animal Science ; Valencia, Elíde
    Se llevaron a cabo tres ensayos con el objetivo de evaluar el consumo voluntario y digestibilidad de nutrientes de heno de gramíneas tropicales nativas (GTN) y ensilaje de sorgo (ES) con o sin suplementación de dos residuos fermentados de pescadería, residuos de la producción de filete de tilapia (RFPT) y lodos fermentados de la industria atunera (LFIA). Además, se evaluó la estabilidad aeróbica de éstos. En el primer ensayo metabólico se determinó el consumo voluntario de forraje y la digestibilidad ``in vivo´´ de la materia seca (MS), proteína bruta (PB) y fibra detergente neutro (FDN) de GTN y ES. Cuatro ovejos criollos adultos se distribuyeron a los tratamientos según un diseño completamente aleatorizado (DCA). Los resultados indicaron un mayor consumo voluntario por parte de los animales alimentados con heno de GTN. La digestibilidad aparente fue mayor para heno de GTN que ES, pero estas diferencias no alcanzaron significaciones estadísticas. En el segundo y tercer ensayos metabólicos se evaluó el efecto de la suplementación con RFPT y LFIA, a niveles de 30% del consumo de MS sobre el consumo y digestibilidad de los forrajes conservados. En ambos experimentos, se utilizaron 8 ovejos adultos distribuidos según un DCA. Se observó que al suplementar los ovejos con RFPT y LFIA aumentó (P <0.05) el consumo voluntario de MS y PB en relación al consumo solo de forraje. Se alcanzaron mayores consumos de MS (P<0.05) con heno de GTN que con ES. La suplementación con ambos residuos fermentados de pescadería tendió a aumentar la digestibilidad aparente de la MS, PB y FDN en el ES. Además, los residuos fermentados de pescadería aumentaron la digestibilidad aparente de la PB y el LFIA aumentó la digestibilidad aparente de la MS en el heno de GTN y solo se observó un efecto negativo en la digestibilidad aparente de FDN cuando se suplemento con LFIA. Por ende, el uso de RFPT y LFIA representa una alternativa para promover el consumo voluntario y en algunos casos aumentar la digestibilidad aparente en rumiantes consumiendo dietas basadas en forrajes tropicales conservados como heno de GTN y ES. Para determinar la estabilidad aeróbica de los residuos fermentados, muestras en triplicado de RFPT y LFIA se expusieron al aire durante 5 días y se analizaron para determinar cambios en pH, temperatura y poblaciones microbianas (bacterias totales y hongos y levaduras). Se observó la temperatura diariamente después de 1, 3 y 5 días de exposición aeróbica y se cuantificó el porcentaje de residuo fermentado recuperado. No se observaron diferencias marcadas en el pH, temperatura, composición química y características fermentativas de los LFIA y RFPT expuestos al aire durante 5 días, lo que sugiere que ambos residuos fermentados de pescadería son aeróbicamente estables.
  • Publication
    Estatus de Atlantea tulita (Dewitz, 1877) en Puerto Rico
    ( 2003) Carrión-Cabrera, Juan E. ; Acosta-Martínez, Jaime A. ; College of Arts and Sciences - Sciences ; Ramos Biaggi, Stuart J. ; Berríos, Ángel ; Department of Biology ; Inglés, Rafael
    The genus Atlantea is endemic to the Greater Antilles (Cuba, Hispaniola, Jamaica and Puerto Rico) with an endemic species in each of the islands. In Puerto Rico it is represented by Atlantea tulita (Dewitz) 1877, a medium sized butterfly (with a wing spread of more or less 6 cm) and singular characteristics. Among these characteristics stand out its sedentary habits, its fidelity to its habitat, the fragility of its imagoes and above all, its monophagy. The butterfly has a close relationship with plants of the genus Oplonia, the only plants used in oviposition and caterpillars food. Habitat destruction has reduced the distribution A. tulita to two extant populations in the island, one in Quebradillas and other in Maricao. The Pollard methodology was slightly modified and used to study population dynamics of tulita in the Puente Blanco area of Quebradillas, Puerto Rico. For fifty-three weeks the area was weekly visited in the morning hours, and in a predetermined route, the number individuals in each instar was recorded. The number of imagoes increases when the number of immature stages decreases, and vice versa, in alternate manner. Male imagoes are always much more common than female imagoes. Inferences and recommendations are made about the situation of A. tulita in Puerto Rico.