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Articles 1 - 15 of 15

Full-Text Articles in Life Sciences

Relationship Of Landscape Structure To Ring-Necked Pheasant Population Dynamics In Northern Iowa , Richard Albert Schmitz Jan 1997

Relationship Of Landscape Structure To Ring-Necked Pheasant Population Dynamics In Northern Iowa , Richard Albert Schmitz

Retrospective Theses and Dissertations

I studied demographic processes that operate on individual animals as a means to understand the relationship of landscape structure to population size and survival. I applied the idea of risk-sensitivity to habitat selection by examining the demographic effects on an animal population in which individuals select from two habitats that have similar mean values for reproductive output but differ in the variance of reproductive output. I conducted simulations using a source-sink population model to show that population size increased with increased variation in habitat quality. I then looked at how landscape heterogeneity was related to ring-necked pheasant (Phasianus colchicus) demography ...


Factors Affecting Cholinesterase Activity In Aquatic Animals , Sheryl Linn Beauvais Jan 1997

Factors Affecting Cholinesterase Activity In Aquatic Animals , Sheryl Linn Beauvais

Retrospective Theses and Dissertations

Organophosphorus insecticides (OPs) are extensively used throughout the world to control crop pests. OPs are highly toxic to aquatic animals and can enter aquatic systems that drain agricultural watersheds, but assessment of an aquatic system's exposure to OPs is difficult as these compounds are non-persistent. Timing of sample collections and expense of analyses make direct monitoring of these insecticides problematic. A reliable and sensitive indicator of OP exposure and resulting toxic effects is needed to integrate across exposure events. A good candidate for the indicator is inhibition of cholinesterase (ChE) enzymes; OPs cause acute toxicity primarily through inhibition of ...


An Approach To Providing Professional Development With An Environmental Education Component To Agriculture Teachers In Costa Rica , Lynne Wood Brookes Jan 1997

An Approach To Providing Professional Development With An Environmental Education Component To Agriculture Teachers In Costa Rica , Lynne Wood Brookes

Retrospective Theses and Dissertations

In 1993 the University of Costa Rica carried out a needs assessment which indicated a widespread need for in-service professional development for high school agriculture teachers. Information was also collected that indicated areas of interest and concern to teachers and the Ministry of Public Education. Subsequently, the University of Costa Rica's Atlantic Regional Center elected to undertake the development and implementation of professional development programs for agriculture teachers. It was determined that the areas to be addressed would include agriculturally oriented environmental education, sustainable agriculture, pedagogy, and methodology useful for information transfer;The objective of this developmental study was ...


Laboratory Studies On The Temperature-Phased Anaerobic Digestion Of Mixtures Of Primary And Waste Activated Sludge , Yue Han Jan 1997

Laboratory Studies On The Temperature-Phased Anaerobic Digestion Of Mixtures Of Primary And Waste Activated Sludge , Yue Han

Retrospective Theses and Dissertations

The temperature-phased anaerobic digestion (TPAD) involves the operation of two reactors in series, the first maintained at a thermophilic temperature (commonly 55° C) and the second maintained at a mesophilic temperature (commonly 35° C).;The purpose of the research was to compare the performance of the temperature-phased system with the conventional single-stage mesophilic system for treating mixtures of primary sludge (PS) and waste activated sludge (WAS). The TPAD systems used in the study consisted of two, completely-mixed reactors operated in series. The first and the second stages were operated at 55° C and 35° C, respectively. The single-stage system was ...


Behavior And Survival Of Nesting Wild Turkeys In Southern Iowa , Michael Wayne Hubbard Jan 1997

Behavior And Survival Of Nesting Wild Turkeys In Southern Iowa , Michael Wayne Hubbard

Retrospective Theses and Dissertations

I studied the population dynamics of an established flock of eastern wild turkeys (Meleagris gallopavo silvestris) in south-central Iowa. I also evaluated the influence of various field methods and marking techniques on wild turkey growth and survival. I conducted a laboratory experiment to examine the effect of transmitter attachment techniques on the growth of turkey poults. Surgically implanted transmitters affected wing growth less than backpack harnesses and are recommended for attaching transmitters to wild turkey poults. I also conducted an analysis evaluating various estimates of wild turkey poult survival. Survival estimates obtained from the flush count method for poults 0-4 ...


Socio-Economic Analysis Of An Agroforestry System With The Winnebago Tribe Of Nebraska , Marcella Brian Szymanski Jan 1997

Socio-Economic Analysis Of An Agroforestry System With The Winnebago Tribe Of Nebraska , Marcella Brian Szymanski

Retrospective Theses and Dissertations

The results from an economic analysis of an agroforestry system and a Participatory Rural Appraisal (PRA) for community land-use decision-making with the Winnebago Tribe of Nebraska are presented as a series of three papers. The dissertation will emphasize different parts of the study with an overall focus on the community development aspects of the agroforestry system. Chapter 1 emphasizes the use of PRA to obtain an emic or "insiders" perspective on the land-use needs of the Winnebago Tribe and community. As a rapid, low-cost method of data collection, PRA techniques have been used as a means of incorporating indigenous knowledge ...


Nitrate Removal Capacity Of Constructed Wetlands , Richard Gregory Phipps Jan 1997

Nitrate Removal Capacity Of Constructed Wetlands , Richard Gregory Phipps

Retrospective Theses and Dissertations

Constructed wetlands at the Des Plaines Wetland Demonstration Project in Wadsworth, Illinois were examined for their capacity to remove nonpoint source loads of nitrate from an agricultural watershed. Three flow through wetlands received different loading rates of pumped river water with seasonably variable loads of nitrate and organic nitrogen. The nitrogen removal capacities of the wetlands were estimated using mass balance and sediment-water microcosms for the 1991 and 1992 field seasons. Concentrations of nitrogen and flow volumes were monitored at inlets and outlets and mass balances of nitrogen loads were calculated. The wetlands received two different loading rates in 1991 ...


Application Of Current Environmental Research To Golf Course Design, Construction, And Management Practices , Mark Gregory Kuiper Jan 1997

Application Of Current Environmental Research To Golf Course Design, Construction, And Management Practices , Mark Gregory Kuiper

Retrospective Theses and Dissertations

The recent proliferation of environmental research on golf courses has greatly expanded the understanding of the environmental impacts and costs of various golf course design, construction, and management strategies. This new body of research, however, has not yet been consolidated into a set of principles for sustainable golf course development and management. The purpose of this research will be to draw from current research to develop such a set of principles and, in particular, to examine the economic and environmental benefits of using native vegetation on golf courses. The objectives of this research were to: -- review and synthesize the large ...


Relationship Between Poplar Leaf Chemicals And Cottonwood Leaf Beetle Adult Feeding Preferences , Sisi Lin Jan 1997

Relationship Between Poplar Leaf Chemicals And Cottonwood Leaf Beetle Adult Feeding Preferences , Sisi Lin

Retrospective Theses and Dissertations

The cottonwood leaf beetle, Chrysomela scripta F. (Coleoptera: Chrysomelidae), is considered to be one of the most serious defoliators of Populus plantations in North America. This research was conducted to understand the relationship between poplar leaf secondary chemicals and adult beetle feeding preferences;Leaf surface chemicals from a cottonwood leaf beetle-preferred poplar clone, 'Eugenei' (Populus deltoides x Populus nigra), was found to induce feeding in the adult cottonwood leaf beetle. The feeding stimulants were isolated and identified as n-beheryl alcohol (C22), n-lignoceryl alcohol (C24), n-hexacosanol (C26), n-octacosanol (C28), n-triacontanol (C30), and [alpha]-tocopherylquinone ([alpha]-TQ), (2-(3-hydroxy-3,7,11,15-tetramethyl-hexadecyl ...


Investigating Components Of The Host-Pathogen Interaction Of Septoria Musiva And Populus , Scott Albert Heuchelin Jan 1997

Investigating Components Of The Host-Pathogen Interaction Of Septoria Musiva And Populus , Scott Albert Heuchelin

Retrospective Theses and Dissertations

Components of host-pathogen interactions in the Septoria musiva-Populus disease system were investigated in an attempt to better understand resistance and susceptiblity to Septoria canker disease. A system for the production and detection of the extracellular proteolytic enzymes produced by Septoria musiva was established using the synthetic medium, casein culture medium (CCM). An isolate of S. musiva (MP1) showed a growth-limiting effect when grown in CCM that contained initial concentrations of <60 mM glucose. SDS PAGE activity gels revealed two putative proteinases, P1 and P2 (M r 24 and 75 kd), in culture filtrates of MP1. Proteinase P1 was isolated and further characterized for optimum pH (8.0) and reaction temperature (60 C). Proteinase inhibitor II (PI II) and phenylmethanesulphonylfluoride (PMSF) reduced proteolytic activity by 55% and 95% respectively. Inclusion of PMSF in SDS PAGE activity gel samples, resulted in inhibition of P1 activity, but not P2 activity. In vitro and in vivo studies were conducted to determine the effect of PI II on the physiology of the fungal pathogen Septoria musiva. PI II reduced in vitro serine proteinase activity in culture filtrates of S. musiva, and reduced conidial germination, mycelial growth, and culture sporulation when the fungus was cultured in medium containing PI II. In vivo tests were conducted with S. musiva and leaf and stem tissues of a transgenic Populus x euramericana clone ('Ogy') that expresses PI II protein. A reduction in lesion size was observed, but there was no significant difference in infection frequency of leaves. Stem inoculation results were inconclusive because of environmental conditions which may have favored host defenses. Expression studies of PI II in transgenic 'Ogy' have revealed an ~24 kd native proteinase inhibitor of Populus that has immunoreactivity to antibodies against PI II. The native inhibitor protein in 'Ogy' has approximately the same biochemical properties, and similar migration patterns, as PI II. A rating system for evaluation of canker disease in Populus clones was developed to standardize ratings of Septoria canker disease. The rating system evaluates both disease incidence and severity and has permitted identification of some possible sources of resistance in hybrid clones of Populus.


The Foraging Behavior Of Anax Junius (Odonata: Aeschnidae) And Its Potential As A Behavioral Endpoint In Pesticide Testing , Sandra Kaye Brewer Jan 1997

The Foraging Behavior Of Anax Junius (Odonata: Aeschnidae) And Its Potential As A Behavioral Endpoint In Pesticide Testing , Sandra Kaye Brewer

Retrospective Theses and Dissertations

I examined the foraging behavior of the green darner dragonfly nymph, Anax junius, to assess the suitability of odonate foraging behavior as a sensitive endpoint for monitoring contaminant exposure. Odonates are potentially excellent organisms for work in biomonitoring programs because: (1) they have complex foraging strategies that tightly couple sensory cues and mechanical responses: (2) their ecology is well-studied: and (3) they are often the dominant invertebrate predator in fishless systems. Thus they have the potential to structure communities through predation;I tested (1) the possibility that nymphs may regulate populations through frequency-dependent foraging and (2) the relationship between head ...


Maternal Expenditure And The Resolution Of Adult-Offspring Conflict In The South American Guanaco , Ronald James Sarno Jan 1997

Maternal Expenditure And The Resolution Of Adult-Offspring Conflict In The South American Guanaco , Ronald James Sarno

Retrospective Theses and Dissertations

I examined patterns of pre-/post-birth maternal expenditure in the polygynous guanaco, Lama guanicoe, in Torres del Paine National Park, Chile from November 1990 to December 1993. Because of presumed greater variance in reproductive success of males of polygynous species, theoreticians have hypothesized that greater energy investment in sons might improve their competitive abilities and lead to increased reproductive success. Thus, it might be adaptive for parent(s) to invest more energy in sons than daughters. The period of parental care in guanacos is also punctuated by an interval of intense adult-offspring conflict. Adult males seasonally defend feeding territories and ...


Evaluation Of Natural Enemies Of The European Corn Borer, Ostrinia Nubilalis (Lepidoptera: Pyralidae) , Mpho Wycliffe Phoofolo Jan 1997

Evaluation Of Natural Enemies Of The European Corn Borer, Ostrinia Nubilalis (Lepidoptera: Pyralidae) , Mpho Wycliffe Phoofolo

Retrospective Theses and Dissertations

The overall objective of this dissertation was to evaluate, both directly and indirectly, the natural enemies of the European corn borer (ECB). The direct evaluation component consisted of two parts: (1) Assessment of the level of naturally occurring mortality of the ECB and evaluation of the impact of biotic and abiotic factors that cause this mortality, and (2) Quantitative evaluation of the impact of augmentative releases of Trichogramma brassicae, a parasitoid of the ECB eggs, on reducing larval densities and damage on corn plants. The indirect laboratory-based evaluation, addressed two factors that affect the efficacy of natural enemies: prey suitability ...


The Effects Of Intensive Agricultural Land-Use Practices On Small Streams In Northwestern Iowa, Jeffery Allen Kopaska Jan 1997

The Effects Of Intensive Agricultural Land-Use Practices On Small Streams In Northwestern Iowa, Jeffery Allen Kopaska

Retrospective Theses and Dissertations

Intensive agricultural land use dominates Iowa's landscape, leading to degradation of the environmental quality of Iowa's land, water, and biota. This study was designed to determine how land use practices affect stream environments in a typical Iowa agricultural landscape. Thirteen first order streams and their watersheds within the Northwest Iowa landform region were studied. Corn and soybeans are grown on the flat headlands of this area, while the steeper terrain is wooded or pastured. Steep erosional topography occurs in association with the Little Sioux River valley. Watershed areas ranged from 72 to 1030 hectares. Geographic Information Systems analysis ...


Hog Industry And Hog Production Related Water Pollution Problem In Taiwan: An Application To Valuing The Willingness To Pay For Improving Water Quality, Kuo-Chang Ro Jan 1997

Hog Industry And Hog Production Related Water Pollution Problem In Taiwan: An Application To Valuing The Willingness To Pay For Improving Water Quality, Kuo-Chang Ro

Retrospective Theses and Dissertations

No abstract provided.