Life Sciences Commons^™

Spatial Variation In Western Corn Rootworm (Coleoptera: Chrysomelidae) Susceptibility To Bacillus Thuringiensis Corn Events In Nebraska, Jordan D. Reinders

Department of Entomology: Dissertations, Theses, and Student Research

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an economically important pest species of field corn (Zea mays L.) in the U.S. Corn Belt. Yield losses and control costs exceed greater than $1 billion annually. Over the past 10+ years, growers have adopted transgenic corn hybrids expressing rootworm-active Bacillus thuringiensis (Bt) proteins as a primary WCR management tactic. Field-evolved resistance to Cry3Bb1 and mCry3A proteins expressed in single-trait Bt hybrids has been confirmed in some areas of Nebraska. Growers have used different tactics as needed to prevent or mitigate resistance, resulting in a mosaic of selection pressure placed …

Evaluation Of Host Plant Resistance Against Sunflower Moth, Homoeosoma Electellum (Hulst), In Cultivated Sunflower In Western Nebraska, Dawn M. Sikora

Department of Entomology: Dissertations, Theses, and Student Research

Sunflower moth, Homoeosoma electellum, is a serious pest of oilseed and confection sunflowers. In this study, we determine efficacy of resistance against this pest. Thirty commercial hybrids, inbreds, and varieties of sunflowers were tested in replicated field and laboratory studies. Trait efficacy is determined by pericarp strength by means of physical compression tests and damage to achenes. Initial sunflower entries were planted May 2014 and data collection began in early August 2014. A second season was planted June 2015, with sampling beginning late August the same year.

In 2014, oilseed varieties showed a strength average of 2.71 ± 0.11 N …

Analysis Of Cereal Aphid Feeding Behavior And Transcriptional Responses Underlying Switchgrass-Aphid Interactions, Kyle G. Koch

Department of Entomology: Dissertations, Theses, and Student Research

Switchgrass, Panicum virgatum L., is a perennial warm-season grass that is a model species for the development of bioenergy crops. However, the sustainability of switchgrass as a bioenergy feedstock will require efforts directed at improved biomass yield under a variety of stress factors. The objectives of this research were to: (1) elucidate greenbug and yellow sugarcane aphid feeding behavior on resistant and susceptible switchgrasses using electronic penetration graphs (EPG), (2) define transcriptional changes before and during insect feeding through RNA-seq to identify candidate resistance genes in a hybrid switchgrass cultivar, and (3) utilize methods in RNA sequencing of insects to …

Conservation Biological Control Of Western Bean Cutworm: Molecular Gut Content Analysis Of Arthropod Predators, Feeding Trials For Key Predators And Agricultural Surveys For Integrated Pest Management, Westen Ray Archibald

Department of Entomology: Dissertations, Theses, and Student Research

Western bean cutworm (WBC), Striacosta albicosta is a major pest of corn in western Nebraska. In 1999, its range expanded into much of North America causing damage from Nebraska to Canada and Mexico. WBC periodically causes kernel damage as severe as 15 bu/ac for one larva/plant. Control for WBC relies on Bt corn hybrids with Vip3A and Cry1F traits and insecticides. There has been a 5.2-fold decrease in efficacy of Cry1F for WBC. Concerns over management tactics may be creating space for conservation biological control to become part of a WBC integrated pest management (IPM) program. Objective 1, used …

Effects Of Temperature And Diet In Stable Fly (Diptera: Muscidae) Development, Melina Florez-Cuadros

Department of Entomology: Dissertations, Theses, and Student Research

Stable flies are among the most important blood feeding ectoparasites of cattle worldwide. The livestock industry is losing more than $2 billion dollar annually in the United States alone. Moist decaying vegetative material with bacteria supports larval development. Temperature and diet quality are important factors for stable fly development, affecting development rates, adult survival, and size, but how temperature affects adult size and interacts with nutrition is unknown. This study characterizes the relationship of temperature and diet quality in the development of stable flies. Two statistical models were used to analyze the effect of temperature alone (Lysyk, 1998) and temperature-diet …