Phenological Floral Resource Complementarity is Important for Bee Abundance

Spatial resource heterogeneity has been found to greatly influence the dynamics between diversity and function. This is particularly relevant for bee diversity and pollination services. While there has been ample research conducted to investigate these patterns, the impact of phenological resource heterogeneity (differences in availability of resources throughout time) on biodiversity and functioning has been less explored. This is important in agricultural systems, as many foraging periods of bees extend beyond the crop flowering event. In this study, we sought to understand how the bee community changed between seasons and if phenological complementarity of non-crop floral resources influenced bee diversity and abundance. We explored these questions in a region dominated by coffee agroecosystems in Mexico. This region was an ideal system for this study because the landscape offers a range of coffee management regimes that maintain heterogeneity in floral resource availability temporally and spatially. We found that the bee community varies significantly between the seasons. There were a greater proportion of native social bees in the rainy season than the dry season. The proportion of solitary bees did not vary between the seasons. Managed social bees had a significantly greater proportion in the dry season when coffee was flowering than all other sampling times. Additionally, we found that floral resources from groundcover, but not trees, were associated with bee abundance. However, the phenological scale of the availability of these resources is important, whereby contemporaneous resource availability appears particularly important in maintaining high bee abundance at sites with lower phenological complementarity through time. We argue that in additional to spatial resource heterogeneity, resource heterogeneity through time is also critical in explaining patterns in the bee community. Farms can support pollinator services and conservation by maintaining complementarity in floral resources available from both crop and non-crop plants.Master of ScienceNatural Resources and EnvironmentUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/122456/1/Kaleigh_Fisher_thesis_2016.pd

Metabolic crosstalk: molecular links between glycogen and lipid metabolism in obesity.

Glycogen and lipids are major storage forms of energy that are tightly regulated by hormones and metabolic signals. We demonstrate that feeding mice a high-fat diet (HFD) increases hepatic glycogen due to increased expression of the glycogenic scaffolding protein PTG/R5. PTG promoter activity was increased and glycogen levels were augmented in mice and cells after activation of the mechanistic target of rapamycin complex 1 (mTORC1) and its downstream target SREBP1. Deletion of the PTG gene in mice prevented HFD-induced hepatic glycogen accumulation. Of note, PTG deletion also blocked hepatic steatosis in HFD-fed mice and reduced the expression of numerous lipogenic genes. Additionally, PTG deletion reduced fasting glucose and insulin levels in obese mice while improving insulin sensitivity, a result of reduced hepatic glucose output. This metabolic crosstalk was due to decreased mTORC1 and SREBP activity in PTG knockout mice or knockdown cells, suggesting a positive feedback loop in which once accumulated, glycogen stimulates the mTORC1/SREBP1 pathway to shift energy storage to lipogenesis. Together, these data reveal a previously unappreciated broad role for glycogen in the control of energy homeostasis

Feeding and Foraging in Bumble bees (Genus: Bombus): From the Organism to the Environment

Animal survival is dependent on the capacity to effectively find and consume nutritious food resources and avoid harmful components that may be present in food. This fundamental process operates at multiple scales in all animal species. At the organismal scale, for example, nutritional state impacts whether an individual is motivated to consume or reject food (Dethier, 1976). The goal of this dissertation research was to establish a foundation for studying feeding and foraging in bumble bees at the scales of the organism, colony, insect-plant interactions, and the environment. Although bumble bee feeding and foraging behavior have been previously studied at most of these scales, there are several substantial gaps in our knowledge that this dissertation addresses. To address these gaps, I first identified taste-related genes in Bombus impatiens and characterized the tissues in which these genes are expressed. I then examined how feeding and food-collection tasks are organized amongst workers in bumble bee colonies. Next, I tested whether pollen nutrients drive floral resource visitation in wild bumble bees. Finally, I examined what bumble bee species are present across several ecoregions in California. Together, this work provides a foundation to study the ecology and evolution of feeding and foraging in bumble bees

Feeding and Foraging in Bumble bees (Genus: Bombus): From the Organism to the Environment

Animal survival is dependent on the capacity to effectively find and consume nutritious food resources and avoid harmful components that may be present in food. This fundamental process operates at multiple scales in all animal species. At the organismal scale, for example, nutritional state impacts whether an individual is motivated to consume or reject food (Dethier, 1976). The goal of this dissertation research was to establish a foundation for studying feeding and foraging in bumble bees at the scales of the organism, colony, insect-plant interactions, and the environment. Although bumble bee feeding and foraging behavior have been previously studied at most of these scales, there are several substantial gaps in our knowledge that this dissertation addresses. To address these gaps, I first identified taste-related genes in Bombus impatiens and characterized the tissues in which these genes are expressed. I then examined how feeding and food-collection tasks are organized amongst workers in bumble bee colonies. Next, I tested whether pollen nutrients drive floral resource visitation in wild bumble bees. Finally, I examined what bumble bee species are present across several ecoregions in California. Together, this work provides a foundation to study the ecology and evolution of feeding and foraging in bumble bees

Colony Development and Reproductive Success of Bumblebees in an Urban Gradient

Approximately 35% of all crop production is dependent on animal-mediated pollination. Many wild bee species are declining rapidly across North America and Europe, a potential consequence of land-use change driven by agricultural intensification and urbanization. In this study we assessed the impact of urbanization on the reproductive success and population growth rate of bumblebees in an urbanization gradient. We placed experimental nests in ten sites; all except one were community gardens, ranging from a 0–99% degree of urbanization. Reproductive success and colony size were positively correlated with cumulative weight gain of the nests (p < 0.05). We did not find an effect of urbanization on the population growth rate of the nests or on forager activity (p > 0.05). Growth rate was strongly negatively affected by the abundance of wax moth larvae (p < 0.05) and positively correlated with parasite diversity (p < 0.05) and the number of foragers entering the nest (p < 0.01). With this study we show that not only bottom-up but also top-down effects are equally important for pollinator population dynamics

Temporal Resource Data

Data was field collected in the Soconusco region of Chiapas Mexico. Data is on floral resource characteristics. Labels: fl=floralresource; abund=abundance; per=percent; gc=groundcover; can=canopy

Data from: Floral resource availability from groundcover promotes bee abundance in coffee agroecosystems

Patterns of bee abundance and diversity across different spatial scales have received thorough research consideration. However, the impact of short and long term temporal resource availability on biodiversity has been less explored. This is highly relevant in tropical agricultural systems for pollinators, as many foraging periods of pollinators extend beyond flowering of any single crop species. In this study, we sought to understand how bee communities in tropical agroecosystems changed between seasons, and if short and long term floral resource availability influenced their diversity and abundance. We used a threshold analysis approach in order to explore this relationship at two time scales. This study took place in a region dominated by coffee agroecosystems in Southern Mexico. This was an ideal system because the landscape offers a range of coffee management regimes that maintain heterogeneity in floral resource availability spatially and temporally. We found that the bee community varies significantly between seasons. There were higher abundances of native social, solitary and managed honeybees during the dry season when coffee flowers. Additionally, we found that floral resources from groundcover, but not trees, were associated with bee abundance. Further, the temporal scale of the availability of these resources is important, whereby short-term floral resource availability appears particularly important in maintaining high bee abundance at sites with lower seasonal complementarity. We argue that in additional to spatial resource heterogeneity, temporal resource heterogeneity is critical in explaining bee community patterns, and should thus be considered to promote pollinator conservation

Data from: Floral resource availability from groundcover promotes bee abundance in coffee agroecosystems

Patterns of bee abundance and diversity across different spatial scales have received thorough research consideration. However, the impact of short and long term temporal resource availability on biodiversity has been less explored. This is highly relevant in tropical agricultural systems for pollinators, as many foraging periods of pollinators extend beyond flowering of any single crop species. In this study, we sought to understand how bee communities in tropical agroecosystems changed between seasons, and if short and long term floral resource availability influenced their diversity and abundance. We used a threshold analysis approach in order to explore this relationship at two time scales. This study took place in a region dominated by coffee agroecosystems in Southern Mexico. This was an ideal system because the landscape offers a range of coffee management regimes that maintain heterogeneity in floral resource availability spatially and temporally. We found that the bee community varies significantly between seasons. There were higher abundances of native social, solitary and managed honeybees during the dry season when coffee flowers. Additionally, we found that floral resources from groundcover, but not trees, were associated with bee abundance. Further, the temporal scale of the availability of these resources is important, whereby short-term floral resource availability appears particularly important in maintaining high bee abundance at sites with lower seasonal complementarity. We argue that in additional to spatial resource heterogeneity, temporal resource heterogeneity is critical in explaining bee community patterns, and should thus be considered to promote pollinator conservation