Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

Retrospective Theses and Dissertations

Environmental Sciences

Entomology

Articles 1 - 17 of 17

Full-Text Articles in Life Sciences

Multitrophic Interactions In Wetlands Infested By An Invasive Species Lythrum Salicaria L., Bethzayda Matos Carrion Jan 2005

Multitrophic Interactions In Wetlands Infested By An Invasive Species Lythrum Salicaria L., Bethzayda Matos Carrion

Retrospective Theses and Dissertations

This dissertation examined insect-plant, predator-prey, and predator-predator interactions as they relate to the invasive plant species Lythrum salicaria L. The first study determined the suitability of two L. salicaria herbivores, Myzus lythri and Galerucella calmariensis for the preimaginal development and survival and influence on adult weight of three predatory species commonly found in L. salicaria infested wetlands, Chrysoperla carnea, Coleomegilla maculata, and Harmonia axyridis. Myzus lythri is suitable prey for preimaginal survival of the three predatory species. Galerucella calmariensis larvae are highly suitable for development and survival of second instar to adult C. carnea and less suitable for H. axyridis ...


Population Genetic Studies Of The Tsetse Fly, Glossina Pallidipes (Diptera: Glossinidae) , Johnson Ouma Odera Jan 2004

Population Genetic Studies Of The Tsetse Fly, Glossina Pallidipes (Diptera: Glossinidae) , Johnson Ouma Odera

Retrospective Theses and Dissertations

Tsetse flies transmit trypanosome species that cause sleeping sickness in humans and nagana in livestock. In the absence of a vaccine against trypanosome parasites and given the high cost of treatment, vector control remains the most effective method for reducing the incidence of trypanosomiasis. In anticipation of area-wide control of G. pallidipes by using genetic methods, a thorough understanding of its breeding structure is required.;Capture release-recapture data show that G. pallidipes has a high capacity for dispersal, but genetic data indicate surprisingly high differentiation among populations. Studying local patterns of genetic variation and examining how such variation changes temporally ...


Corn Rootworms (Coleoptera: Chrysomelidae) In Space And Time , Yong-Lak Park Jan 2003

Corn Rootworms (Coleoptera: Chrysomelidae) In Space And Time , Yong-Lak Park

Retrospective Theses and Dissertations

Spatial dispersion is a main characteristic of insect populations. Dispersion pattern provides useful information for developing effective sampling and scouting programs because it affects sampling accuracy, efficiency, and precision. Insect dispersion, however, is dynamic in space and time and largely dependent upon interactions among insect, plant and environmental factors. This study investigated the spatial and temporal dynamics of corn rootworm dispersion at different spatial scales by using the global positioning system, the geographic information system, and geoStatistics and Probability; Egg dispersion pattern was random or uniform in 8-ha cornfields, but could be aggregated at a smaller scale. Larval dispersion pattern ...


Evaluation Of Prairie Grasses For Reducing The Environmental Impact Of Herbicide Contamination , Jason B. Belden Jan 2003

Evaluation Of Prairie Grasses For Reducing The Environmental Impact Of Herbicide Contamination , Jason B. Belden

Retrospective Theses and Dissertations

The primary goal of this dissertation was to evaluate the use of prairie grasses for reducing the environmental impact of herbicides. Studies included: use of prairie grasses as a phytoremediation tool for contaminated soil; comparison of grass species for use in vegetative buffer strips; fate of 14C-pendimethalin in vegetated and unvegetated soil; and environmental hazards of pendimethalin contaminated soil.;Throughout this dissertation, evidence was presented that prairie grasses can increase the dissipation rate of herbicides. In one study, 78% less metolachlor and 39% less pendimethalin remaining in vegetated treatments as compared to unvegetated treatments. In a separate study, the presence ...


The Influence Of Vegetation, Microbial Inoculation, And Aging Of Pesticide Residues On The Degradation Of Atrazine And Metolachlor In Soils , Shaohan Zhao Jan 2001

The Influence Of Vegetation, Microbial Inoculation, And Aging Of Pesticide Residues On The Degradation Of Atrazine And Metolachlor In Soils , Shaohan Zhao

Retrospective Theses and Dissertations

The bacteria Agrobacterium radiobacter J14a and Pseudomonas sp. strain ADP and the enzyme atrazine chlorohydrolase all had a significant effect on the degradation of atrazine in Alpha soil, a soil with a low indigenous atrazine-mineralizing population. However, inoculation with J14a did not increase the atrazine degradation in Bravo soil, a soil with a high number of indigenous atrazine-mineralizing microorganisms. This suggests that the ability of J14a to enhance the degradation of atrazine is affected by the presence of indigenous atrazine-mineralizing microorganisms. Inoculation of Pseudomonas fluorescens UA5-40 did not enhance the transformation of metolachlor in either soil.;The ability of native ...


Winter Survival And Population Dynamics Of Bean Leaf Beetle (Coleoptera: Chrysomelidae) , Wai-Ki Frankie Lam Jan 1999

Winter Survival And Population Dynamics Of Bean Leaf Beetle (Coleoptera: Chrysomelidae) , Wai-Ki Frankie Lam

Retrospective Theses and Dissertations

Ecological study of the population dynamics of bean leaf beetle adults, Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), with special reference to the overwintering populations, was conducted in central Iowa. Ecological habits, spatial distribution, cold tolerance, and winter survival of overwintering beetle adults, were studied for 3-yr (1996 through 1999). Additionally, the population fluctuation of the adult beetles during the growing season was studied for 10-yr, from 1989 through 1998, inclusively. Overwintering beetle adults mostly hibernated in the crop residue of soybean fields ( ≈ 20%) and leaf litter of woodlands ( ≈ 80%). A few beetles (< 1%) overwintered in alfalfa fields, cornfields, and grasslands. The overwintering adults aggregated in the litter of soybean fields and woodlands. Residue in the habitats served as an insulating layer for the overwintering beetles. However, over 50% mortality of the overwintering beetles was observed in both soybean fields and woodlands during the 3-yr study. Laboratory study indicated that most of the overwintering beetles survived more than hundreds of hours when they were kept at --5°C or above, whereas most of the beetles died when they were kept at --10°C or below. This result indicated that cold temperature has a strong effect on the winter survival of the overwintering populations. A model for the estimation of the mortality of overwintering beetle adults, based on the accumulation of the air mean subfreezing winter temperature, was developed. Linear regression and multiple regression stepwise selection procedure analyses were used to relate environmental factors to population fluctuations of bean leaf beetle during the 10-yr study. The analyses showed a strong relationship between the environmental factors, including temperature and precipitation, and beetle population densities. A predictive model for F2 adults in the next late season was developed. The major factors affecting the survival of overwintering populations and population fluctuations of the beetles, estimation of winter survival, and the prediction of the population dynamics of bean leaf beetle during seasonal cycles are discussed.


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 ...


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 ...


The Fate Of Methyl Bromide, Ethylene Glycol, And Propylene Glycol In Soil And Surface Water: Influence Of Soil Variables And Vegetation On Degradation And Offsite Movement , Patricia Jane Rice Jan 1996

The Fate Of Methyl Bromide, Ethylene Glycol, And Propylene Glycol In Soil And Surface Water: Influence Of Soil Variables And Vegetation On Degradation And Offsite Movement , Patricia Jane Rice

Retrospective Theses and Dissertations

Within the last few years methyl bromide (MeBr), ethylene glycol (EG), and propylene glycol (PG) have become environmental concerns due to their adverse impact on the environment. The purpose of our research was to study each compound within the framework of where and how they are environmental concerns by (1) investigating the influence of soil environmental variables on the degradation and mobility of MeBr in soil and (2) evaluating the use of vegetation to reduce soil infiltration and remediate soil and surface waters contaminated with aircraft deicing agents (EG, PG). Our research indicates MeBr rapidly volatilized from fumigated soil and ...


The Persistence, Degradation, And Mobility Of Metolachlor In Soil And The Fate Of Metolachlor And Atrazine In Surface Water, Surface Water/Sediment, And Surface Water/Aquatic Plant Systems , Pamela Joan Rice Jan 1996

The Persistence, Degradation, And Mobility Of Metolachlor In Soil And The Fate Of Metolachlor And Atrazine In Surface Water, Surface Water/Sediment, And Surface Water/Aquatic Plant Systems , Pamela Joan Rice

Retrospective Theses and Dissertations

Metolachlor and atrazine are two of the most widely used herbicides in the Midwest. Detection of pesticides in drinking water resources has increased interest in the environmental fate of these compounds in soil, surface water, and groundwater. The persistence of a compound and its adsorption to soil are the two most important factors related to the off-site movement of pesticides from the soil to groundwater or surface water. The aim of my research was to (1) study the environmental fate of metolachlor in soil and evaluate its potential to become a groundwater contaminant and (2) investigate the persistence of metolachlor ...


Enhanced Degradation Of Pesticide Wastes In Soil: Implications For Bioremediation Of Agrochemical Dealer Sites , Ellen Louise Kruger Jan 1996

Enhanced Degradation Of Pesticide Wastes In Soil: Implications For Bioremediation Of Agrochemical Dealer Sites , Ellen Louise Kruger

Retrospective Theses and Dissertations

The fate of atrazine and metolachlor, applied as a mixture, in soils taken from pesticide-contaminated sites (Alpha and Bravo) was determined in laboratory studies. Mineralization of metolachlor (less than 1%) in the Bravo sites was minimal after a 30-d. Degradation of metolachlor was greater in the Kochia scoparia rhizosphere soil. The amount of mineralization of atrazine at the Alpha site was as high as 62% of the applied 14C. A mass balance of the 14C applied revealed significant differences (p < 0.05) between the two soil types in soil bound residues, 14CO2, and the extractable organic fraction. The half-life for atrazine was significantly less in the rhizosphere soil (p < 0.05) with a half-life of 50 d compared to 193 d in the nonvegetated soils. A 14C-most-probable-number procedure was also carried out on soils from the pesticide-contaminated sites to determine specific atrazine and metolachlor degraders;To determine the influence of the presence of plants on the degradation of aged herbicide contaminants, vegetated and nonvegetated soil studies were conducted. The percent of applied 14C-atrazine remaining as atrazine in soil which was nonvegetated, or planted with Brassica napus or Kochia scoparia was 9.3, 6.5, and 4.2%, respectively. Combustion of plants revealed that 11% of the applied radioactivity was taken up in Kochia scoparia, while less than 1% was taken up in Brassica napus plants;A screening study was conducted to determine if soils obtained from several pesticide-contaminated sites had enhanced degradative capability to degrade four freshly applied herbicides. Atrazine mineralization was extensive in four of the soils. Minimal mineralization of pendimethalin, alachlor, and metolachlor was seen in this study. Atrazine, metolachlor, and trifluralin were applied in all possible combinations at a rate of 200 [mu]g/g each to soils exhibiting enhanced atrazine degradation in order to determine if higher concentrations and mixtures would inhibit degradation. Only the atrazine was radiolabeled. Rapid mineralization of atrazine occurred in all soil treatments, with 60% to 80% mineralization after 9 weeks;Deethylatrazine degradation was enhanced in soils which had received long-term exposure to atrazine compared with soils that had not received long-term atrazine exposure.


Assessment Of Coleomegilla Maculata (Coleoptera: Coccinellidae) Predation Of The Colorado Potato Beetle (Coleoptera: Chrysomelidae) , Joseph Munyaneza Jan 1996

Assessment Of Coleomegilla Maculata (Coleoptera: Coccinellidae) Predation Of The Colorado Potato Beetle (Coleoptera: Chrysomelidae) , Joseph Munyaneza

Retrospective Theses and Dissertations

The functional response, foraging behavior, and developmental and reproductive responses of fourth instars and adults of the predatory lady beetle Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae) were investigated under laboratory, greenhouse, and field conditions. Prey were eggs of Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). Coleomegilla maculata fourth instars exhibited a type II functional response to L. decemlineata eggs under laboratory, greenhouse, and field conditions. The maximum attack rate in the field was about half of that observed in the laboratory or greenhouse. The differences in prey density and environmental conditions seem to be major contributing factors in determining the ...


Degradation Of Chlorpyrifos In Soil: Effect Of Concentration, Soil Moisture, And Temperature , James Henry Cink Jan 1995

Degradation Of Chlorpyrifos In Soil: Effect Of Concentration, Soil Moisture, And Temperature , James Henry Cink

Retrospective Theses and Dissertations

The dissipation of the organophosphorus insecticide chlorpyrifos was investigated in field and laboratory samples. Six field locations were selected within the United States, and included the states of Arizona, Florida, Hawaii, Iowa, Mississippi, and Texas. Five of the six locations were selected based on their suspected aggressive degradative capabilities towards this chemical;In the field study, chlorpyrifos was applied to surficial trenches prepared on the north and south side of each building and parallel to the foundation. In the soil samples from Florida, Hawaii, and Texas, concentrations decreased by more than 50% of the initial concentration within 3 mo of ...


The Effects Of Fertilizers And Earthworms On Entomopathogenic Nematodes , David Ian Shapiro Jan 1994

The Effects Of Fertilizers And Earthworms On Entomopathogenic Nematodes , David Ian Shapiro

Retrospective Theses and Dissertations

Entomopathogenic nematodes in the genus Steinernema are promising biological control agents of soil insect pests. Two factors which may influence efficacy of biological control applications are virulence and dispersal of nematodes. This research examined the influence of fertilizers on the virulence of nematodes and the effects of earthworm presence on nematode dispersal;The virulence of Steinernema carpocapsae (Weiser) was determined in soil amended with fertilizer treatments of fresh cow manure, composted manure, and urea. Urea and fresh manure reduced nematode virulence in laboratory experiments. Field experiments, however, only indicated reduced nematode virulence in soil amended with fresh manure. Soil amended ...


The Perceptions Of Iowa Farmers Toward Integrated Pest Management, And, Beauveria Bassiana (Balsamo) Vuillemin In The Corn Ecosystem: Its Effect On Coleomegilla Maculata Degeer, Randall Lee Pingel Jan 1991

The Perceptions Of Iowa Farmers Toward Integrated Pest Management, And, Beauveria Bassiana (Balsamo) Vuillemin In The Corn Ecosystem: Its Effect On Coleomegilla Maculata Degeer, Randall Lee Pingel

Retrospective Theses and Dissertations

No abstract provided.


Leaf Age Heterogeneity Among Selected Populus Clones: 1 Influences On Feeding And Oviposition Preferences Of Adult Chrysomela Scripta F (Coleoptera: Chrysomelidae): 2 Correlations Of Preferences With Foliar Phenolic Glycoside Profiles , Barbara Ruth Bingaman Jan 1991

Leaf Age Heterogeneity Among Selected Populus Clones: 1 Influences On Feeding And Oviposition Preferences Of Adult Chrysomela Scripta F (Coleoptera: Chrysomelidae): 2 Correlations Of Preferences With Foliar Phenolic Glycoside Profiles , Barbara Ruth Bingaman

Retrospective Theses and Dissertations

The cottonwood leaf beetle, Chrysomela scripta F., (Coleoptera: Chrysomelidae), is considered to be one of the more serious defoliators of plantation Populus in North America. This research was undertaken to examine the effects of leaf age and plant chemicals on the feeding and oviposition behaviors of adult beetles. The most preferred leaf age class was established for both behaviors and the composition and concentration of selected phenolic glycosides were analyzed for the most and least preferred leaf age classes. Correlations were then made between the phenolic glycoside profiles of the leaves and the host preferences of the beetles for both ...


The Crawfishes Of Mississippi: With Special Reference To The Biology And Control Of Destructive Species , Clay Lyle Jan 1937

The Crawfishes Of Mississippi: With Special Reference To The Biology And Control Of Destructive Species , Clay Lyle

Retrospective Theses and Dissertations

No abstract provided.