Anthropogenic landscape changes threaten our ecologically and economically critical honey bees by decreasing the availability of quality foraging resources. Importantly, waggle dance analysis provides a versatile and relatively cost-effective tool for investigating the obstacles that honey bees face, such as habitat loss, in our changing landscapes. While this emerging tool has improved our understanding of honey bee foraging in specific landscape contexts, additional research is needed to identify broad trends that span across landscapes. For this dissertation, I used waggle dance decoding and analysis to investigate honey bee foraging, and sublethal stress responses, across three ecologically distinct landscapes in Virginia. In Chapter 1, I introduce waggle dances as a model study system for investigating honey bee foraging and sublethal stress responses by summarizing modern methodological advances in its analysis and emerging research gaps. In Chapter 2, I tested the effects of sublethal imidacloprid exposure on honey bee foraging and recruitment using a semi-field feeder experiment. In doing so, I report that honey bees decreased their foraging, but not recruitment, to an imidacloprid-laced sucrose solution, compared to a control solution. Together, these effects could potentially harm honey bee health by increasing their exposure to pesticides and decreasing their food intake. In Chapter 3, I compared the foraging distances communicated by waggle dancing nectar and pollen foragers across landscapes to explore the economic forces driving foraging to these resources. I observed higher overall and monthly nectar foraging distances compared to pollen foraging distances. Such results suggest that nectar foraging cost dynamics are driven by supply, while pollen foraging cost dynamics are driven by demand. In Chapter 4, I used waggle dance decoding to map and quantify foraging to agricultural grasslands in a mixed-use landscape. In doing so, I demonstrate that honey bees recruit to agricultural grasslands throughout the season, but that this land type was not more attractive than the broader landscape after correcting for foraging distance, which is a relevant cost that flying bees must consider. Additionally, I qualitatively observe a foraging hot spot, representing high honey bee interest, over a highly heterogenous section of the landscape. The collective results of this chapter identify agricultural grasslands as a potential management target and support the importance of landscape heterogeneity to honey bees/pollinators. In Chapter 5, I used waggle dance decoding to investigate honey bee foraging spatial patterns in the context of optimal foraging theory. In particular, I explore whether co-localized honey bee colonies forage optimally by converging on the same resource patches, or by partitioning the landscape in to distinct foraging territories. Spatial analysis revealed that the colonies widely distributed their foraging at the landscape-scale, with dances from the same and different colonies being similarly distributed, while also establishing distinct, patch-scale, colony-specific, foraging aggregations. Together, these results suggest that the honey bee foraging system produces an emergent foraging pattern that may decrease both within- and among-colony foraging competition. Finally, in Chapter 6, I place my research findings in the context of historical and current trends in honey bee behavioral ecology. Overall, my dissertation improves our understanding of honey bee foraging ecology across landscape contexts using waggle dance analysis, while demonstrating its versatility and effectiveness as a tool for ecologists. / Doctor of Philosophy / Honey bees collect nectar (carbohydrate source) and pollen (protein source) from flowers as their food for survival and reproduction. Human activities, such urbanization, change landscapes and threaten our critically important honey bees by decreasing the availability of flower-rich habitats. Importantly, honey bees share the location of good food sources with their nest mates using a communication behavior called the waggle dance. Interestingly, scientists can estimate the approximate location of the food sources communicated by waggle dancing bees through close observation and cutting-edge analysis. Therefore, we can "decode" honey bees' waggle dances to map their food collection, or foraging, patterns and investigate the obstacles that they face in our changing landscapes. For this dissertation, I used waggle dance decoding and analysis to investigate honey bee foraging across three different landscapes in Virginia. In Chapter 1, I introduce waggle dances as a tool for investigating honey bee behavior by summarizing the modern improvements in its analysis and areas where research is needed. In Chapter 2, I tested the effects of a sublethal exposure to a pesticide, imidacloprid, by observing the foraging and waggle dance behavior of bees visiting feeders with artificial food. I report that honey bees decreased their foraging, but not recruitment, while collecting an imidacloprid-laced sugar solution, compared to a solution without imidacloprid. In Chapter 3, I compared the foraging distances communicated by waggle dancing nectar and pollen foragers across landscapes to explore the economic forces driving foraging to these resources. I observed higher overall and monthly nectar foraging distances compared to pollen foraging distances. Such results suggest that nectar foraging is driven by supply, while pollen foraging is more driven by demand. In Chapter 4, I used waggle dance decoding to map and quantify foraging to agricultural grasslands (pastures and hay fields) in a landscape characterized by diverse land uses. In doing so, I demonstrate that honey bees recruit to agricultural grasslands throughout the season, but that this land type was not more attractive than the broader landscape after correcting for foraging distance. Additionally, I qualitatively observe a foraging hot spot, representing high honey bee interest, over a highly heterogenous section of the landscape. The collective results of this chapter identify agricultural grasslands as a potential management target and support the importance of landscape heterogeneity to honey bees/pollinators. In Chapter 5, I used waggle dance decoding to investigate the spatial patterns of honey bee foraging in the context of optimal foraging theory, which attempts to explain efficient resource collection strategies. In particular, I explore whether neighboring honey bee colonies forage optimally by converging on the same resource patches, or by dividing the landscape in to distinct foraging territories. We found that colonies distributed their foraging widely at the landscape-scale, with dances locations from the same and different colonies being similarly distributed, while also establishing distinct, patch-scale, colony-specific, foraging areas. Together, these results suggest that honey bees use a foraging strategy that decreases both within- and among-colony foraging competition. Finally, in Chapter 6, I place my research findings in the context of historical and current trends in honey bee behavioral ecology. Overall, my dissertation uses waggle dance analysis to improve our understanding of honey bee foraging behavior, while demonstrating its versatility and effectiveness as a tool for ecologists.

Virginia dairy producers are considering intensive grazing as a profitable and ecologically viable alternative to confinement dairy production. The objective of this study is to compare financial performance for pasture-based dairy farms relative to similar resourced-based confinement farms. Comparisons are based on the recommended financial and profitability measures of performance provided by the Farm Financial Standards Council. Primary and secondary data plus simulation of daily pasture supply and animal demands are used to develop 100 and 200-cow farms with a land base representative of the Ridge and Valley regions of Virginia. Representative farms were developed to explore financial performance based on the intensity of pasture use, from total confinement to seasonal farms using intensive grazing (in which pasture, hay, and energy supplements are the only sources of nutrients for all dairy animals on the farm). Results of the analysis demonstrate that pasture-based seasonal production is more profitable and has a higher level of repayment capacity and financial efficiency than all other production systems in this study. Greater financial performance by the seasonal farms is obtained even though such farms obtain lower average annual milk prices and 10 percent less milk sold per cow than the similar confinement farms. Pasture-based farms that feed a partial total mixed ration during the summer (25 percent of ration dry matter and 45 percent of ration dry matter from pasture) have fewer financial advantages than the seasonal farms. However, their performance exceeds that of the confinement farms and intensive pasture-based farms milking year round. The intensive pasture-based farms milking year round are the poorest financial performers. Additional conclusions for this study are: 1) the 100-cow farms exhibit insufficient financial performance to provide for family living, debt service (at 40 percent debt to equity ratio), and a cushion for events such as droughts or declines in milk prices; and 2) financial performance of the 200-cow dairies is better, yet the added income from a member of the farm having off-farm income will provide a cushion against unforeseen production and financial risks. Follow up research should address the interface of three issues; stocking rates, farm profitability, and environmental compliance. / Ph. D.

No description available.

The lack of forage resources in the Sahelian region of Mali is a major constraint to food production and food sufficiency. Madiama commune is located in northern Mali, in the Niger Delta region. Three separate experiments were conducted to investigate ways to improve pasture resources and productivity. The first experiment (2003) was designed to investigate the influence of sheep grazing tethered at two different residual heights on botanical composition, forage biomass and animal performance. Young sheep weighing approximately 18-24 kg were tethered for a certain period of time depending on residual canopy height. Two treatments 3 or 6 cm residual height were each replicated 4 times. Animals were rotated based on canopy height and each tethered animal followed an 8 paddock rotation. Measurements included forage biomass, plant diversity, animal performance, and botanical composition. The forage species found on these pastures were primarily Schoenfeldia gracilis, Panicum laetum, Setaria palludefusca, Eragrostis turgida, Eragrostis tremula, Zornia glauchidiata, Tephrosia pedicellata, and Cynodon spp. Accumulated seasonal forage biomass increased while forage quality declined as the growing season progressed. Treatment had only a slight effect on animal weight gains (1 to 3kg season-1). These results suggest that residual height may not affect livestock gain. The second experiment was designed to investigate the potential of Cassia tora (C. tora) which is an invasive weed in the region as a supplemental feed for livestock. Cassia tora was harvested within the Madiama commune and ensiled with or without additives (water and or honey/sugar) for 60 or 90 days. Harvest occurred at the vegetative stage in year 1 and mature growth stage in year 2. Prior to placing the chopped material in the bags for ensiling, sub-samples of fresh C. tora were obtained for dry matter (DM) and chemical analysis (NDF, ADF, CP, IVDMD and TDN). In year 1, the ensiled material/fresh material across treatments and locations had NDF varying from 48 to 56 %/ 56 to 57%, ADF from 34 to 41 %/40 to 42%, CP from 9 to 10 %/9 to 23%, and IVDMD from 53 to 64 %/52 to 54%. In year 2, CP averaged twice as much as year 1 with significantly less fiber probably due to the fact that harvest occurred at the vegetative stage. Addition of water or sugar/honey improved the nutritive values of the ensiled material. These results suggest that C. tora can be a reliable feed source during the dry season. A greenhouse experiment was conducted using various P sources (Tilemsi phosphate rock (TPR), North Carolina phosphate rock (NCPR), Aluminum phosphate (AlP), Iron phosphate (FeP), and Triple superphosphate (TSP) and rates (0, 20, 40, 60, and 80 mg P kg-1 soil). Plants were grown for 10 wks, harvested and separated into above and below ground plant parts. The root and plant material were dried, ground and analyzed for elemental P. The result showed variable P solubility and uptake by the plant. Overall, addition of P resulted in an increase in above ground biomass as well as root mass compared with the untreated control. Field and greenhouse experiments showed that in the Sahel region of Africa where feed resources are scarce 8 out of 12 months a year, anything we can do to increase pasture resources and animal productivity while maintaining a healthy ecosystem, could improve the quality of life in the community. / Ph. D.

Angus cows (Bos taurus) with calves and 1/2 Dorset, 1/4 Finn and 1/4 Rambouillet ewes (Ovis aries) with lambs grazed Kentucky bluegrass (Poa pratensis) - white clover (Trifolium repens) in a randomized block design with three replications during 3 yr, to investigate effects of grazing cattle and sheep together and separately on soils, plants and animals. Additionally, changes in stocking rate, seasonal distribution of cool-season forages and varying nutritional requirements of animals were examined. There were 6 cow-calf pairs or 6 ewes with 11 lambs per replication of cattle alone and sheep alone treatments. Six cows plus six ewes, with their offspring, were allotted to each replication of mixed grazed pastures. Initial stocking rates were equilibrated among treatments to 1 cow and calf per .45 ha. Grazing sheep alone increased (P < .05) percentage bluegrass (58%) but decreased white clover (6%) and weeds (36%), compared to pastures grazed only by cattle (30, 16 and 53%, respectively, which was similar to initial composition). Soils in mixed grazed pastures remained higher (P < .05) in plant nutrients, pH, and percent organic matter and were less (P < .05) compacted, compared to soils where sheep or cattle grazed alone. Total forage mass and quality were higher (P < .05) in mixed grazed pastures, compared to pastures grazed by cattle and sheep alone. Daily gain (.23 kg/d), total gain (23 kg), and weaning weights (43 kg) of lambs were higher (P < .01) in pastures grazed by both animal species, compared to sheep alone (.18 kg/d, 19 and 38 kg, respectively). These animals also reached target weaning weights (43 kg) 14 d earlier (P < .05) than those grazed alone. Body condition of ewes was improved by the breeding season, compared to ewes grazed alone. Five measuring techniques were investigated to determine forage mass and botanical composition. Measurements based on small plots permanently located within pastures were as accurate as those based on the entire pasture. Visual estimations of forage mass were lower, compared to hand clipping, but reflected canopy height. Visual evaluations more accurately estimated presence of individual plant species than hand separated samples. Grazing ewes and cows with associated spring-born offspring on bluegrass-white clover improved the balance between plant growth and animal forage requirements and improved sustainability of the soil-plant-animal system. / Ph. D.

In terms of acreage, forage is the number one crop in Virginia. The backbone of these forages has long been tall fescue (Lolium arundinaceum (Schreb.) S.J. Darbyshire). Knowledge of the plant species that make up a pasture and the relative amounts of each species present is important for interpreting potential animal performance. It is also important to know the relative amounts and types of weeds present and to monitor for the presence of poisonous plants or noxious weeds. An experiment was conducted in 2003 through 2005 to investigate botanical composition and yield of "Lakota" prairie grass (Bromus catharticus Vahl.), "Kentucky 31" endophyte-infected (KY31 E+), endophyte-free (KY31 E-), and "Quantum" tall fescue (non toxic endophyte infected) under grazing by stocker steers. Forage botanical composition and yield were determined by clipping three 0.25-m2 areas per treatment replicate. Prior to harvesting, the canopy height within each quadrate was measured with a disc meter. In 2005, productive ground cover was assessed using visual evaluation techniques, point quadrat method, and digital imagery quantified with terrestrial remote sensing. Forages were established September 2002 and grazing was initiated in July of 2003. Experimental design was a randomized complete block with four replications. Averaged over the three years the yield of KY31E+ was higher (p<0.05) than all other treatments. Lakota prairie grass had lower (p<0.05) yields than both KY31 E+ and Quantum tall fescue, however no yields did not differ between Lakota prairie grass and KY31 E-. Our results showed a typical forage distribution curve for all the treatments. Early spring, summer, and fall productivity of Lakota prairie grass was less than all the fescues, thus did not extend the grazing season. Forage persistence was greatest for KY31 E+ and Quantum and lowest for Lakota when averaged over all years. Among sampling methods for ground cover, terrestrial remote sensing was the most accurate, compared with visual evaluation and point quadrat methods. For estimates of all yield indirect methods of assessment had high errors; however the plate meter calibrated by sward density seemed the least variable of the methods tested. / Master of Science

<p dir="ltr"><a href="" target="_blank">Shoot architecture in plants refers to the spatial layout of the above-ground organs, which develops through complicated networks of genetic and environmental interactions. Modification of shoot architecture has been a major driver of yield increases in many crop species, but knowledge of the genetic control of shoot architectural traits in soybeans remains incomplete. Chapter 1 provides an overview of soybean shoot architecture traits, encompassing stem growth habit, plant height, branch number, branch angle, petiole angle, leaf size, and leaf shape. The review not only delves into the genetic basis of these traits but also underscores their importance, identifies knowledge gaps, and outlines avenues for future research leveraging cutting-edge technologies in gene editing, phenomics, and genomics. Chapter 2 describes the identification and mapping of a novel locus modulating semideterminate and indeterminate stem growth habits, <i>dt3</i>, on chromosome 10. Allelic and haplotypic analysis of the USDA soybean germplasm collection was conducted to find semideterminate soybean accessions which did not carry known stem termination alleles at the <i>dt1</i> and <i>Dt2 </i>loci. Mapping populations were developed by crossing several of these accessions to indeterminate cultivars, and initial mapping revealed a region on chromosome 10 common to all populations. <i>dt3</i> is a recessive mutation resulting in semideterminate growth habits, and this locus displays a unique pattern of inheritance compared with known stem growth habit genes in soybean or other plant species. Chapter 3 describes the identification of <i>Dt4</i>, a novel semideterminacy allele of <i>FT5a</i> originating from wild soybean. <i>Dt4</i> was identified by quantitative trait locus (QTL) mapping using a population developed by crossing LD00-3309, an indeterminate cultivar with a semideterminate recombinant inbred line (RIL1890) originating from a cross between wild and domesticated soybean. A combination of fine mapping and candidate gene expression analysis pinpointed the allele of the floral inducer <i>FT5a</i> in RIL1890 as <i>Dt4 </i>for semideterminacy. Intriguingly, when the <i>Dt4 </i>allele was transformed into LD00-3309, it resulted in not only semideterminate stem growth habit but also narrowed leaf shape. Chapter 4 describes the identification and mapping of <i>GmBa1</i>, a novel locus specifying soybean branch angle, in which wide branch angle is completely dominant over narrow branch angle. This locus was identified in two distinct biparental mapping populations. The findings described in this dissertation deepen our understanding of genetic mechanisms underlying shoot architecture traits and provide a valuable resource for breeders looking to modify these traits for soybean improvement.</a></p>

Virginia beef producers have been overwhelmed with increasing costs and decreasing profits as well as facing challenges such as development pressures, drought, increasing competition for grazing land. Together these have reduced opportunities for expansion and often increased incentives for farmers to sell land for non-agriculture use. Nevertheless, opportunities exist for the Virginia beef market. Consumer demand is changing and consumers are seeking food from alternative production systems based on attributes related to human health, environment, animal welfare, and other social concerns. Consumers are also interested in increasing their consumption of locally produced foods. Specialty beef such as natural, organic, and pasture-fed addresses the changing consumer demand and provides alternatives to commodity beef production. This thesis analyzes the potential for and the constraints to specialty beef producers in Virginia to sell their beef through alternative market outlets such as large retail outlets, specialty stores, restaurants, or direct to consumers. The study will research the potential demand for specialty beef through alternative market outlets, the market entry requirements to supply specialty beef to these alternative outlets, and the potential for Virginia's specialty beef producers to serve as suppliers to these alternative outlets. A survey is used to evaluate these alternative markets and determine if they present an opportunity for Virginia producers of specialty beef. The results of this study will evaluate the viability of selling and buying between producer and retailer and offer valuable information and recommendations to Virginia specialty beef producers about the potential and requirements in each of these markets. / Master of Science

In Virginia, tall fescue [(Schedonorus phoenix (Scop.) Holub,) formally known as Festuca arundinacea L.] can be found on more than 4 million ac of hay and pastureland. Two separate experiments were conducted at three different geographical locations over two growing seasons. The objective of Experiment 1 was to evaluate the influence of N sources and rates on yield and nutritive value of stockpiled tall fescue. Experiment 2 examined the effect of split spring and fall N applications at various rates on yield and nutritive value of tall fescue pastures. The first experiment was conducted at three locations (Blacksburg, Blackstone, and Steeles Tavern, VA) while the second experiment was conducted only at the Blacksburg and Steeles Tavern locations. In Experiment 1, the N sources included ammonium nitrate, ammonium sulfate, urea, urea + Agrotain®, Environmentally Smart N® (ESN), Nutrisphere (NSN), Nitamin® (Blackstone only), pelleted biosolids (Blackstone only), and broiler litter (Steeles Tavern only) applied at 0, 28, 56, 84, and 112 kg plant available N (PAN) ha-1. Plots were harvested in mid-December (Blacksburg and Steeles Tavern) and late January (Blackstone). The yield of the stockpiled tall fescue in 2006 ranged from 1,300 to 2,900, 1,700 to 3,000, and 2,600 to 3,300 kg DM ha-1 for the Blacksburg, Steeles Tavern and Blackstone locations, respectively. In 2007, however, the yield response to N rate and sources was significantly less than that of 2006 due to low rainfall. At the Blacksburg location, ammonium sulfate and ESN resulted in higher CP concentrations, ranging from 11-14% and 12-20% for 2006 and 2007 growing seasons, respectively. Similar variation (12-20%) was observed for the Steeles Tavern location in 2006. In general, the ADF and NDF content decreased as N rate increased from 0-112 kg ha1. Although the source and rate that resulted in high yield and nutritive value varied across location and years, N rates and sources improved the quality and yield of stockpiled fescue. Experiment 2 utilized urea which was applied in the fall at the rates of 0, 45, 90 or 135 kg N ha-1. followed by spring application of 0, 45, 90 or 135 kg N ha-1. A total of 16 treatment combinations per replication were used. Yields ranged from 1,900 to 3,600 kg DM ha-1 and 700 to 2,500 kg DM ha-1 in 2007 and 2008, respectively. At the Steeles Tavern location, yields ranged from 3,100 to 5,700 kg DM ha-1 and 2,500 to 5,100 kg DM ha-1, in 2007 and 2008, respectively. In both years CP increased with increasing N fertilization. On a dry matter basis, CP values ranged from 14 to 23% for both years. Treatments did not affect on NDF and ADF values. Split fall/spring N applications did not maximize yield of cool-season grass pastures in these experiments. / Master of Science

The study undertaken was carried out in the montane tussock grassland region which in the South Island comprises some six million acres. Field trials were established at Mt Somers, Mid Canterbury. This study attempts to elucidate some of the factors connected with the sulphur nutrition of grasses. For the particular trial area it was hoped to determine four key aspects ; 1. Whether the response of the grass to nitrogen is governed by the sulphur level available. 2. A determination of what level of nitrogen was likely to be provided by clover fixation and transferred to the grass component under improved grassland conditions in the area. 3. What the optimum level of sulphur for the association is, allowing adequate sulphur for maximum possible nitrogen fixation as well as for utilization by the grass of the nitrogen transferred. 4. The effects of nitrogen and sulphur on plant chemical composition and any possible relationships between plant and soil as infuenced by these factors. Following a review of literature, a summary of experimental work is presented, with results, discussion and conclusions.