Ecology and Evolutionary Biology Commons^™

Assessment Of Cover Crop Management Strategies In Nebraska, Us, Maxwel C. Oliveira, Liberty Butts, Rodrigo Werle

West Central Research and Extension Center, North Platte

Adoption of cover crops has the potential to increase agricultural sustainability in the US and beyond. In 2017, a survey was conducted with Nebraska stakeholders in an attempt to evaluate current cover crop management strategies adopted in soybean (Glycine max [L.] Merr.), field corn (Zea mays L.), and seed corn production. Eighty-two Nebraska stakeholders answered the survey, of which 80% identified themselves as growers. Eighty-seven percent of respondents manage cover crops, and the average cover crop ha planted on a per farm basis is 32%. The primary method of establishing cover crops following soybeans and field corn is …

Developmental And Reproductive Characteristics Of Beef Heifers Classified By Number Of Estrous Cycles Experienced By Start Of First Breeding, Andy Roberts, Jaclyn N. Ketchum, Richard N. Funston

West Central Research and Extension Center, North Platte

A retrospective analysis was conducted to evaluate the effect of number of estrous cycles exhibited before breeding on growth and reproductive performance of replacement beef heifers fed ad-libitum or restricted by 20% less than ad-libitum during postweaning development over a 9-yr period. Progesterone concentration in blood samples collected at 9- to 11-d intervals were used to assign heifers into groups by number of estrous cycles exhibited before the start of breeding: 0 (nonpubertal; n = 395), 1 (n = 205), 2 (n = 211), 3 (n = 116), or >3 (n = 249). Heifers (P …

Evaluation Of Foliar Insecticides For The Control Of Western Bean Cutworm In Field Corn, 2018, Katharine A. Swoboda-Bhattarai, Samantha R. Daniel, Julie A. Peterson

West Central Research and Extension Center, North Platte

The objectives of this field trial were to evaluate the efficacy of single applications of foliar insecticides at preventing feeding damage by the western bean cutworm (WBC), an important pest of corn and dry beans that has undergone a rapid range expansion into the eastern Corn Belt during the last 18 yr. This study was conducted within the historic range of WBC, at the University of Nebraska-Lincoln’s Henry J. Stumpf International Wheat Center in Perkins County, NE (40.856851°N, −101.701335°W). An RCB design with a total of 16 treatments (including an untreated check) and four replications was used. Plots measured 20 …

Fungicide Application Technology For Controlling The Sugarcane Orange Rust, Thales Cassemiro Alves, João Arantes Rodrigues Da Cunha, Rafael Marcão Tavares, Guilherme Sousa Alves, Sérgio Macedo Silva

West Central Research and Extension Center, North Platte

With the epidemic onset of the sugarcane orange rust, fungicide applications of the Strobilurins and Triazoles groups have become necessary in susceptible varieties. This study aimed at evaluating the operational conditions of fungicide application in sugarcane (SP81-3250 variety), in relation to the spray deposition on the upper canopy and the effectiveness of the orange rust control. Treatments consisted of two application volumes (30 L ha-1 or 40 L ha-1) and three nozzle deflection angles (0 º, 90 º or 135 º), plus a ground application at the rate of 200 L ha-1, sprayed with a uniform flat spray nozzle of …

Response Of Amaranthus Spp. Following Exposure To Sublethal Herbicide Rates Via Spray Particle Drift, Bruno C. Vieira, Joe D. Luck, Keenan L. Amundsen, Todd A. Gaines, Rodrigo Werle, Greg Kruger

West Central Research and Extension Center, North Platte

The adverse consequences of herbicide drift towards sensitive crops have been extensively reported in the literature. However, little to no information is available on the consequences of herbicide drift onto weed species inhabiting boundaries of agricultural fields. Exposure to herbicide drift could be detrimental to long-term weed management as several weed species have evolved herbicide-resistance after recurrent selection with sublethal herbicide rates This study investigated the deposition of glyphosate, 2,4-D, and dicamba spray particle drift from applications with two different nozzles in a low speed wind tunnel, and their impact on growth and development of Amaranthus spp. Herbicide drift …

Droplet Size And Nozzle Tip Pressure From A Pulse–Width Modulation Sprayer, Thomas R. Butts, Liberty E. Butts, Joe D. Luck, Bradley K. Fritz, Wesley C. Hoffmann, Greg R. Kruger

West Central Research and Extension Center, North Platte

Pulse-width modulation (PWM) sprayers can improve application accuracy through flow control, turn compensation, and high-resolution overlap control by pulsing an electronically-actuated solenoid valve which controls the relative proportion of time each solenoid valve is open (duty cycle). The objective of this experiment was to identify the droplet size distribution and nozzle tip pressure when influenced by PWM duty cycle, nozzle technology, and gauge pressure to provide PWM guidelines. The experiment was conducted in a low-speed wind tunnel at the Pesticide Application Technology Laboratory using a SharpShooter® PWM system. In general, for non-venturi nozzles, as duty cycle decreased, droplet size slightly …

Approaches To Evaluating Grower Irrigation And Fertilizer Nitrogen Amount And Timing, Tsz Him Lo, Daran Rudnick, Charles Burr, Matt Stockton, Rodrigo Werle

West Central Research and Extension Center, North Platte

Diversity in the knowledge, mindset, strategies, and tools that growers use to manage irrigation and fertilizer nitrogen culminates in diversity in profitability and environmental impact among farms. As growers, academia, and industry strive together to tackle the technological and non-technological challenges impeding better irrigation and fertilizer nitrogen management, a science-based evaluation of grower input amount and timing becomes an important initial step in the process. Providing such valuable feedback to growers is a high-priority objective for the University of Nebraska-Lincoln Testing Ag Performance Solutions (UNL-TAPS) farm management competition. In this competition, each team of mostly growers made management decisions for …

Droplet Size Impact On Efficacy Of A Dicamba-Plus-Glyphosate Mixture, Thomas R. Butts, Chase A. Samples, Lucas X. Franca, Darrin M. Dodds, Daniel B. Reynolds, Jason W. Adams, Richard K. Zollinger, Kirk A. Howatt, Bradley K. Fritz, W. Clint Hoffmann, Joe D. Luck, Greg R. Kruger

West Central Research and Extension Center, North Platte

Chemical weed control remains a widely used component of integrated weed management strategies because of its cost-effectiveness and rapid removal of crop pests. Additionally, dicamba-plus-glyphosate mixtures are a commonly recommended herbicide combination to combat herbicide resistance, specifically in recently commercially released dicamba-tolerant soybean and cotton. However, increased spray drift concerns and antagonistic interactions require that the application process be optimized to maximize biological efficacy while minimizing environmental contamination potential. Field research was conducted in 2016, 2017, and 2018 across three locations (Mississippi, Nebraska, and North Dakota) for a total of six site-years. The objectives were to characterize the efficacy of …

Weed Science Research Summary 2019: Progress Report Of Phd Student Regarding Weed Control, Jesaelen Gizotti De Moraes

West Central Research and Extension Center, North Platte

2017-2018 Interaction of Lactofen with Glyphosate or Glufosinate for Weed Control as Affected by Adjuvants and Droplet Size

2018 Effect of Adjuvants on Physical Properties of Glyphosate and PPO-Inhibiting Herbicide Spray Mixtures

2019 Management of Troublesome Weeds in XtendFlex^® Soybeans

2019-2020 Soybean Symptomatology and Yield Response to Sub-Labeled Doses of Dicamba and 2,4-D

Evaluation Of Foliar Insecticide Application Timing For The Control Of Western Bean Cutworm In Field Corn, 2018, Katharine A. Swoboda-Bhattarai, Samantha R. Daniel, Julie A. Peterson

West Central Research and Extension Center, North Platte

The objective of this field trial was to determine if application timing affects the efficacy of single applications of foliar insecticides at preventing feeding damage by the western bean cutworm (WBC), an important pest of corn and dry beans in the North American Corn Belt. This study was located at the University of Nebraska- Lincoln’s Henry J. Stumpf International Wheat Center in Perkins County, NE (40.856851°N, −101.701335°W). The experimental design used was an RCB design with a total of 10 treatments (three insecticides applied at three application timings, plus an untreated check) and four replications; the treatment design was an …

Maximizing Ecosystem Services Provided To The New Oil Crop Brassica Carinata Through Landscape And Arthropod Diversity, Shane Stiles

Electronic Theses and Dissertations

Prairies, once spanning the Upper Midwest, have now largely been replaced by agriculture. The lack of resources available to pollinators in agricultural fields and the practices employed by farmers to maximize yield has led to a decline in insect and pollinator diversity. There is a need to better understand how ecosystem services provided by a diverse insect community scale to current farming practices as they relate to crop yield. We sought to explain how landscape heterogeneity relates to insect and pollinator diversity, as well as how insect diversity relates to crop yield across common farming practices. To evaluate how farming …

Diversifying Cornfields By Interseeding Cover Crops: Practical Implications And The Response Of Invertebrate Communities, Michael Bredeson

Electronic Theses and Dissertations

The lack of suitable habitat conditions for beneficial organisms in simplified agroecosystems leads to unstable invertebrate communities and overreliance on chemical control of herbivores. It is possible to manage pest populations without agrichemicals by manipulating farmland so that herbivores are impaired by plant-driven bottom-up and enemy-driven top-down antagonisms. Interseeding cover crops between established crop rows is a method used by farmers to improve habitat suitability for natural enemies and hinder host-finding, feeding and movement by herbivores. Here I address three important research gaps related to interseeding cover crops. A calcium carbonate seed coating, used to improve seed-broadcasting efficiency, was tested …

Quantifying White-Tailed Deer Density And Its Impacts On Agricultural Systems, Jonathan A. Matthews

Theses and Dissertations--Forestry and Natural Resources

White-tailed deer (Odocoileus virginianus) commonly consume row crops, with yield losses often attributed to their browsing. Deer density and field morphology may predict yield losses within local areas. We sought to 1) determine the effects of deer browsing on corn and soybean yields and investigate if deer density or field morphology correlated to yield loss in western Kentucky, and 2) compare pellet-based distance sampling to game camera surveys to determine if a distance sampling technique could accurately estimate deer density during the growing season. Overall, deer reduced corn and soybean yields on one-half of surveyed properties. Deer density …

European Starlings Fly Before They Fledge, Jeremiah L. Psiropoulos, Lisa A. Selner

Human–Wildlife Interactions

Aircraft bird strikes are increasing globally. Bird strikes constitute a major human health and safety risk and result in millions of dollars in economic impacts. Invasive avian species, such as the European starling (Sturnus vulgaris; starlings), have been implicated in bird strikes in North America. Because this species is highly adaptive and has been successful at establishing in new areas, such as airports, it is essential that managers better understand the potential risks and how to mitigate them. Herein we present a case study regarding a novel observation of unique starling nesting behavior that may pose a risk …

Drought And Coyotes Mediate The Relationship Between Mesopredators And Human Disturbance In California, Molly K. Parren

Cal Poly Humboldt theses and projects

Mesopredators in California are facing two major changes to their ecosystem: drought and the expansion of human disturbance. As a result, mesopredators are likely shifting their habitat use as well as their interspecies interactions to balance resource needs and risk-taking on the landscape. In response to severe drought, the California Department of Fish and Wildlife deployed 585 camera traps throughout the Mojave Desert and Central Valley documenting mammalian mesopredator presence in a drought year (2016) and a post-drought year (2017). The objectives of this study were to examine spatial patterns of mesopredator occurrence and co-occurrence with a dominant predator, the …

Effects Of Acute Hypoxia On Danio Rerio, Karly Crail

Williams Honors College, Honors Research Projects

The purpose of this research experiment was to determine the effects of acute hypoxia on the embryonic zebrafish (Danio rerio) cardiovascular system and assess the critical oxygen level at which embryonic function is compromised. This goal was achieved by exposing embryos to decreasing oxygen concentrations, (6.0 mg/L-0 mg/L) and observing the heart under an inverted microscope. Data analysis was conducted to determine end systolic volume, end diastolic volume, stroke volume, heart rate, and cardiac output. It was hypothesized that hypoxia would stimulate cardiac activity, because in early developmental stages, tissues are supplied with oxygen through bulk diffusion, and …

A Review Of Rat Lungworm Infection And Recent Data On Its Definitive Hosts In Hawaii, Chris N. Niebuhr, Susan I. Jarvi, Shane R. Siers

Human–Wildlife Interactions

Rat lungworm (Angiostrongylus cantonensis) is a zoonotic nematode that causes rat lungworm disease (angiostrongyliasis), a potentially debilitating form of meningitis, in humans worldwide. The definitive hosts for rat lungworm are primarily members of the genus Rattus, with gastropods as intermediate hosts. This parasite has emerged as an important public health concern in the United States, especially in Hawaii, where the number of human cases has increased in the last decade. Here we discuss the current knowledge of the rat lungworm, including information on the life cycle and host species, as well as updates on known infection levels. Three …

Spatial Associations Of Livestock Guardian Dogs And Domestic Sheep, Julie Young, John P. Draper, Daniel Kinka

Human–Wildlife Interactions

Livestock guardian dogs (Canis lupus familiaris; LGDs) have been used for centuries to protect livestock, primarily domestic sheep (Ovis aries), from depredation by large carnivores. While previous studies have shown their efficacy, the mechanisms in which LGDs protect livestock have largely remained unstudied. Livestock guardian dogs are often considered to be effective only if they remain in spatial proximity to the livestock they are protecting. We determined space use of LGDs relative to domestic sheep on open-range grazing allotments used by working ranches in the Rocky Mountains area of the northwest United States between August 2012 …

Application Strategy For An Anthraquinone-Based Repellent And The Protection Of Soybeans From Canada Goose Depredation, Scott J. Werner, Matthew Gottlob, Charles D. Dieter, Joshua D. Stafford

Human–Wildlife Interactions

Agricultural crops can sustain extensive damage caused by Canada geese (Branta canadensis) when these crops are planted near wetlands or brood-rearing sites. From 2000 to 2015, South Dakota Game, Fish and Parks spent >$5.6 million to manage damages caused by Canada geese to agricultural crops (primarily soybeans) in South Dakota, USA. For the purpose of developing a repellent application strategy for nonlethal goose damage management, we comparatively evaluated the width of anthraquinone applications (i.e., 9.4 L Flight Control^® Plus goose repellent/ha [active ingredient: 50% 9,10-anthraquinone] at 0–36 m versus 0–73 m perpendicular to the edge of wetlands …

Cost–Benefit Analysis Of Coyote Removal As A Management Option In Texas Cattle Ranching, R. Kyle Brewster, Scott E. Henke, Benjamin L. Turner, John M. Tomeček, Alfonso Ortega-S.

Human–Wildlife Interactions

The monetary value of livestock losses attributed to coyote (Canis latrans) predation in North America has increased during the past 20 years. In Texas, USA alone in 2011, these loses were estimated at $6.9 million. To mitigate coyote-related livestock losses, several lethal and nonlethal control methods have been developed. However, there remains a need for better information to guide management decisions regarding cost-effective predator control strategies for livestock production systems. We acquired data, which was used in the model, from published literature from 1960 to present day, subject matter experts, and anecdotal information on coyote ecology. We developed …

Shizen Nōhō: Restoring The Relationship Between Food, Nature, And People In Japan, Katharine Graham

Scripps Senior Theses

In Japan’s postwar era, agriculture has become highly industrialized, involving heavy machinery, chemical fertilizers, and pesticides, all in the name of “progress.” Through employing such practices, humans have attempted to improve upon nature’s way of doing things, and in turn have degraded the soil’s fertility, natural ecosystems, and human health. In response to this, Shizen Nōhō has emerged in Japan as an alternative way of cultivating food. Shizen Nōhō practitioners challenge the notion that we need chemical fertilizers, pesticides, and machinery to farm successfully. Rather, they advocate for a way of growing food that functions seamlessly with natural ecosystems. This …

Just Preservation, Adrian Treves, Francisco J. Santiago-Ávila, William S. Lynn

Animal Sentience

We are failing to protect the biosphere. Novel views of conservation, preservation, and sustainability are surfacing in the wake of consensus about our failures to prevent extinction or slow climate change. We argue that the interests and well-being of non-humans, youth, and future generations of both human and non-human beings (futurity) have too long been ignored in consensus-based, anthropocentric conservation. Consensus-based stakeholder-driven processes disadvantage those absent or without a voice and allow current adult humans and narrow, exploitative interests to dominate decisions about the use of nature over its preservation for futurity of all life. We propose that authentically non-anthropocentric …

The New Natural Distribution Area Of Aspen (Populus Tremula L.) Marginal Populations In Pasinler In The Erzurum Province, Turkey, And Its Stand Characteristics, Halil Bariş Özel, Sezgin Ayan, Serdar Erpay, Bojan Simovski

Aspen Bibliography

Background and Purpose: Genetic diversity is the basis for adaptation and survival of tree species under changing environmental conditions, representing the key issue of stability and productivity of forest ecosystems. This paper studies the marginal population characteristics and stand dynamics of aspen tree (Populus tremula L.) in natural, pure and mixed forest stands with Scots pine (Pinus sylvestris L.). These populations were observed on founding sites between Timarli Valley and Timan Plateau located in Pasinler in the Erzurum Province in Turkey.
Materials and Methods: Three replicated sample sites were established according to a randomised block design …

Dependence Of Aspen Stands On A Subsurface Water Subsidy: Implications For Climate Change Impacts, D. M. Love, M. D. Venturas, J. S. Sperry, P. D. Brooks, J. L. Pettit, Y. Wang, W. R. L. Anderegg, X. Tai, D. S. Mackay

Aspen Bibliography

The reliance of 10 Utah (USA) aspen forests on direct infiltration of growing season rain versus an additional subsurface water subsidy was determined from a trait- and process-based model of stomatal control. The model simulated the relationship between water supply to the root zone versus canopy transpiration and assimilation over a growing season. Canopy flux thresholds were identified that distinguished nonstressed, stressed, and dying stands. We found growing season rain and local soil moisture were insufficient for the survival of 5 of 10 stands. Six stands required a substantial subsidy (31–80% of potential seasonal transpiration) to avoid water stress and …

Engineering Eden: The World's Attempt To Outsmart Water Scarcity, Kaitlin A. Sullivan

Capstones

Countries around the world are running out of fresh water, 43 already live with water scarcity, requiring more water than they have. In 2015 the global water crisis took first place in The World Economic Forum’s assessment of the risks that will have the most significant impact on economies, environments and people. Water beat out 27 other long-term risks including infectious diseases and weapons of mass destruction. What happened to Crowley County on the plains of Southeastern Colorado is a cautionary tale of borrowed water. It's been called the Detroit of Colorado, decimated by the reliance of a single industry. …

Phylogeographic Analyses Of A Widely Distributed Populus Davidiana: Further Evidence For The Existence Of Glacial Refugia Of Cool‐Temperate Deciduous Trees In Northern East Asia, Zhe Hou, Zhaoshan Wang, Zhanyang Ye, Shuhui Du, Shuya Liu, Jianguo Zhang

Aspen Bibliography

Despite several phylogeographic studies had provided evidence to support the existence of glacial refugia of cool‐temperate deciduous trees in northeast China, the species used in these studies were limited by the species ranges, which could not exclude the possibility that northern populations were the colonists from southern refugial populations during the last glacial maximum (LGM). Here, we estimated the nucleotide variation in Populus davidiana, a widespread species distributed in Eurasia. Three groups in northeast, central, and southwest China were constructed according to the simulation results from SAMOVA, composition of chloroplast haplotypes and structure results. We revealed that the northeast …

Phylogeny And Population Genetic Analyses Reveals Cryptic Speciation In The Bombus Fervidus Species Complex (Hymenoptera: Apidae), Jonathan B. Koch, Juanita Rodriguez, James P. Pitts, James P. Strange

Ecology Center Publications

Bumble bees (Bombus Latrielle) are significant pollinators of flowering plants due to their large body size, abundant setae, and generalist foraging strategies. However, shared setal coloration patterns among closely and distantly related bumble bee species makes identification notoriously difficult. The advent of molecular genetic techniques has increased our understanding of bumble bee evolution and taxonomy, and enables effective conservation policy and management. Individuals belonging to the North American Bombus fervidus species-complex (SC) are homogenous in body structure but exhibit significant body color phenotype variation across their geographic distribution. Given the uncertainty of the genealogical boundaries within the SC, some …

Wild Bees Of Grand Staircase-Escalante National Monument: Richness, Abundance, And Spatio-Temporal Beta-Diversity, Olivia Messinger Carril, Terry Griswold, James Haefner, Joseph S. Wilson

All PIRU Publications

Interest in bees has grown dramatically in recent years in light of several studies that have reported widespread declines in bees and other pollinators. Investigating declines in wild bees can be difficult, however, due to the lack of faunal surveys that provide baseline data of bee richness and diversity. Protected lands such as national monuments and national parks can provide unique opportunities to learn about and monitor bee populations dynamics in a natural setting because the opportunity for large-scale changes to the landscape are reduced compared to unprotected lands. Here we report on a 4-year study of bees in Grand …

Analysis Of An Agent-Based Model For Integrated Pest Management With Periodic Control Strategies, Timothy Comar, Elizabeth Rodriguez

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Justice Served Fresh: Associations Between Food Insecurity, Community Gardening, And Property Value, Micajah Daniels, Courtney Coughenour Ph.D

McNair Poster Presentations

Numerous stakeholders in Nevada have used a variety of efforts to combat the growth of food insecurity facing Nevadans. The purpose of this research project is to understand the association between food insecurity, community gardens, and property value. Following the wealth of scholarship on these topics and data collected from community garden agencies in Southern Nevada, the research questions for this project include: (1) Where are community gardens located in SNV? (2) What efforts community gardens agencies are doing to address food insecurity (most interested in their efforts using community gardens)? (3) What are the perceptions of supports and barriers …