scholarly journals Kinematic flexibility allows bumblebees to increase energetic efficiency when carrying heavy loads

2020 ◽  
Vol 6 (6) ◽  
pp. eaay3115
Author(s):  
Stacey A. Combes ◽  
Susan F. Gagliardi ◽  
Callin M. Switzer ◽  
Michael E. Dillon
Keyword(s):  
Metabolic Rate ◽  
Force Production ◽  
Bombus Impatiens ◽  
Energetic Efficiency ◽  
Loading History ◽  
Energetic Costs ◽  
Additional Loading ◽  
Heavy Loads ◽  
Load Size ◽  
Stroke Amplitude

Foraging bees fly with heavy loads of nectar and pollen, incurring energetic costs that are typically assumed to depend on load size. Insects can produce more force by increasing stroke amplitude and/or flapping frequency, but the kinematic response of a given species is thought to be consistent. We examined bumblebees (Bombus impatiens) carrying both light and heavy loads and found that stroke amplitude increased in proportion to load size, but did not predict metabolic rate. Rather, metabolic rate was strongly tied to frequency, which was determined not by load size but by the bee’s average loading state and loading history, with heavily loaded bees displaying smaller changes in frequency and smaller increases in metabolic rate to support additional loading. This implies that bees can increase force production through alternative mechanisms; yet, they often choose the energetically costly option of elevating frequency, suggesting associated performance benefits that merit further investigation.

scholarly journals Metabolic rate predicts the lifespan of workers in the bumble bee Bombus impatiens

Apidologie ◽  
2019 ◽  
Vol 50 (2) ◽  
pp. 195-203 ◽  
Author(s):  
Evan P. Kelemen ◽  
Nhi Cao ◽  
Tuan Cao ◽  
Goggy Davidowitz ◽  
Anna Dornhaus
Keyword(s):  
Metabolic Rate ◽  
Bombus Impatiens ◽  
Bumble Bee

Deformable Blade Element and Unsteady Vortex Lattice Fluid-Structure Interaction Modeling of a 2D Flapping Wing

2020 ◽  
Author(s):  
Joseph Reade ◽  
Mark A. Jankauski
Keyword(s):  
Vortex Lattice ◽  
Normal Force ◽  
Aerodynamic Force ◽  
Fluid Structure Interaction ◽  
Force Production ◽  
Flapping Wing ◽  
Energetic Efficiency ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Blade Element

Abstract Flapping insect wings experience appreciable deformation due to aerodynamic and inertial forces. This deformation is believed to benefit the insect’s aerodynamic force production as well as energetic efficiency. However, the fluid-structure interaction (FSI) models used to estimate wing deformations are often computationally demanding and are therefore challenged by parametric studies. Here, we develop a simple FSI model of a flapping wing idealized as a two-dimensional pitching-plunging airfoil. Using the Lagrangian formulation, we derive the reduced-order structural framework governing wing’s elastic deformation. We consider two fluid models: quasi-steady Deformable Blade Element Theory (DBET) and Unsteady Vortex Lattice Method (UVLM). DBET is computationally economical but does not provide insight into the flow structure surrounding the wing, whereas UVLM approximates flows but requires more time to solve. For simple flapping kinematics, DBET and UVLM produce similar estimates of the aerodynamic force normal to the surface of a rigid wing. More importantly, when the wing is permitted to deform, DBET and UVLM agree well in predicting wingtip deflection and aerodynamic normal force. The most notable difference between the model predictions is a roughly 20° phase difference in normal force. DBET estimates wing deformation and force production approximately 15 times faster than UVLM for the parameters considered, and both models solve in under a minute when considering 15 flapping periods. Moving forward, we will benchmark both low-order models with respect to high fidelity computational fluid dynamics coupled to finite element analysis, and assess the agreement between DBET and UVLM over a broader range of flapping kinematics.

Regulation of intestinal glucose absorption: A new issue in animal science

1998 ◽  
Vol 78 (1) ◽  
pp. 1-13 ◽  
Author(s):  
W. James Croom Jr ◽  
Brian McBride ◽  
Anthony R. Bird ◽  
Yang-Kwang Fan ◽  
Jack Odle ◽  
...  
Keyword(s):  
Peptide Yy ◽  
Basolateral Membrane ◽  
Phenotypic Expression ◽  
Genetic Selection ◽  
Glucose Absorption ◽  
Energetic Efficiency ◽  
Production Traits ◽  
Energetic Costs ◽  
Energy Expenditures ◽  
Intestinal Glucose Absorption

Intestinal glucose absorption occurs via Na+-dependent glucose cotransporters (SGLT1) located in the luminal membrane of enterocytes and is driven by an electrochemical gradient maintained by Na+/K+ ATPase located on the basolateral membrane. Twenty percent of whole animal energy expenditures can be accounted for by the gastrointestinal tract, most of which is the result of Na+/K+ ATPase function. Active intestinal glucose transport is regulated by a number of gastrointestinal peptides such as epidermal growth factor (EGF) and peptide YY (PYY). PYY and EGF can upregulate intestinal glucose absorption by as much as 200–300%. Of special interest is the fact that the energetic costs of intestinal tissue function can vary in relationship to the amount of glucose transported. This value termed "apparent energetic efficiency of glucose uptake" (APEE) may be of value in evaluating the energetic costs of glucose and other nutrients during various physiological and nutritional states. Recent studies suggest that intensive genetic selection for production traits in poultry may result in intestinal absorption being rate-limiting for full phenotypic expression of these traits. Further research is needed to clarify this issue. Key words: Glucose absorption, intestinal, energy metabolism, peptides, genetic selection

scholarly journals Reconstructing Full-Field Flapping Wing Dynamics from Sparse Measurements

2020 ◽  
Author(s):  
William Johns ◽  
Lisa Davis ◽  
Mark Jankauski
Keyword(s):  
Aerodynamic Force ◽  
Force Production ◽  
Energetic Efficiency ◽  
Reconstruction Technique ◽  
Reconstruction Method ◽  
Full Field ◽  
Insect Wing ◽  
Insect Wings ◽  
Flying Insects ◽  
Sparse Measurements

AbstractFlapping insect wings deform during flight. This deformation benefits the insect’s aerodynamic force production as well as energetic efficiency. However, it is challenging to measure wing displacement field in flying insects. Many points must be tracked over the wing’s surface to resolve its instantaneous shape. To reduce the number of points one is required to track, we propose a physics-based reconstruction method called System Equivalent Reduction Expansion Processes (SEREP) to estimate wing deformation and strain from sparse measurements. Measurement locations are determined using a Weighted Normalized Modal Displacement (NMD) method. We experimentally validate the reconstruction technique by flapping a paper wing from 5-9 Hz with 45° and measuring strain at three locations. Two measurements are used for the reconstruction and the third for validation. Strain reconstructions had a maximal error of 30% in amplitude. We extend this methodology to a more realistic insect wing through numerical simulation. We show that wing displacement can be estimated from sparse displacement or strain measurements, and that additional sensors spatially average measurement noise to improve reconstruction accuracy. This research helps overcome some of the challenges of measuring full-field dynamics in flying insects and provides a framework for strain-based sensing in insect-inspired flapping robots.

The Developmental Efficiency of the Avian Embryo

1927 ◽  
Vol 5 (1) ◽  
pp. 43-54
Author(s):  
JOSEPH NEEDHAM
Keyword(s):  
Growth Rate ◽  
Metabolic Rate ◽  
Basal Metabolism ◽  
Energetic Efficiency ◽  
Avian Embryo ◽  
Efficiency Coefficient

1. The "Coefficient d'Utilisation" or Plastic Efficiency Coefficient (P.E.C.) has been calculated for each day during development. It has a trough which is deepest between the eighth and ninth days; development is therefore most expensive at this point. The correlation between this and the point of greatest intensity of protein combustion is exact. 2. The "Rendement Energétique brut" or Apparent Energetic Efficiency has been calculated for each day during development. It rises, changing more rapidly towards the end than at the beginning; thus it resembles the metabolic rate rather than the growth rate. The "Rendement Energétique réel" or Real Energetic Efficiency cannot at present be calculated for the basal metabolism of the embryo is unknown and it is not certain whether the usual conceptions of basal metabolism can be applied to a rapidly growing and changing organism.

scholarly journals Costly steroids: egg testosterone modulates nestling metabolic rate in the zebra finch

2007 ◽  
Vol 3 (4) ◽  
pp. 408-410 ◽  
Author(s):  
Michael Tobler ◽  
Jan-Åke Nilsson ◽  
Johan F Nilsson
Keyword(s):  
Metabolic Rate ◽  
Competitive Ability ◽  
Resting Metabolic Rate ◽  
Taeniopygia Guttata ◽  
Energetic Costs ◽  
Offspring Performance ◽  
Nestling Growth ◽  
Prenatal Testosterone ◽  
Yolk Hormones ◽  
Resting Metabolism

The transfer of non-genetic resources from mother to the offspring often has considerable consequences for offspring performance. In birds, maternally derived hormones are known to influence a variety of morphological, physiological and behavioural traits in the chick. So far, the range of these hormonal effects involves benefits in terms of enhanced growth and competitive ability as well as costs in terms of immunosuppression. However, since yolk hormones can enhance growth and begging activity, high levels of these hormones may also involve energetic costs. Here, we show experimentally that elevated levels of prenatal testosterone increase resting metabolic rate in nestling zebra finches ( Taeniopygia guttata ). Surprisingly, however, elevation of prenatal testosterone did not result in higher growth rates and, thus, differences in resting metabolism do not seem to be linked to nestling growth. We conclude that apart from immunosuppressive effects, high levels of egg steroids may also entail costs in terms of increased energy expenditure.

scholarly journals Endocrine Disruption Alters Developmental Energy Allocation and Performance in Rana temporaria

2019 ◽  
Vol 59 (1) ◽  
pp. 70-88 ◽  
Author(s):  
Katharina Ruthsatz ◽  
Kathrin H Dausmann ◽  
Steffen Reinhardt ◽  
Tom Robinson ◽  
Nikita M Sabatino ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Endocrine Disruption ◽  
Rana Temporaria ◽  
Energy Allocation ◽  
Environmental Stressors ◽  
Endocrine Function ◽  
Independent Effect ◽  
Energetic Efficiency ◽  
Metamorphic Climax ◽  
Carry Over

Abstract Environmental change exposes wildlife to a wide array of environmental stressors that arise from both anthropogenic and natural sources. Many environmental stressors with the ability to alter endocrine function are known as endocrine disruptors, which may impair the hypothalamus–pituitary–thyroid axis resulting in physiological consequences to wildlife. In this study, we investigated how the alteration of thyroid hormone (TH) levels due to exposure to the environmentally relevant endocrine disruptor sodium perchlorate (SP; inhibitory) and exogenous L-thyroxin (T4; stimulatory) affects metabolic costs and energy allocation during and after metamorphosis in a common amphibian (Rana temporaria). We further tested for possible carry-over effects of endocrine disruption during larval stage on juvenile performance. Energy allocated to development was negatively related to metabolic rate and thus, tadpoles exposed to T4 could allocate 24% less energy to development during metamorphic climax than control animals. Therefore, the energy available for metamorphosis was reduced in tadpoles with increased TH level by exposure to T4. We suggest that differences in metabolic rate caused by altered TH levels during metamorphic climax and energy allocation to maintenance costs might have contributed to a reduced energetic efficiency in tadpoles with high TH levels. Differences in size and energetics persisted beyond the metamorphic boundary and impacted on juvenile performance. Performance differences are mainly related to strong size-effects, as altered TH levels by exposure to T4 and SP significantly affected growth and developmental rate. Nevertheless, we assume that juvenile performance is influenced by a size-independent effect of achieved TH. Energetic efficiency varied between treatments due to differences in size allocation of internal macronutrient stores. Altered TH levels as caused by several environmental stressors lead to persisting effects on metamorphic traits and energetics and, thus, caused carry-over effects on performance of froglets. We demonstrate the mechanisms through which alterations in abiotic and biotic environmental factors can alter phenotypes at metamorphosis and reduce lifetime fitness in these and likely other amphibians.

Hummingbird hovering performance in hyperoxic heliox: effects of body mass and sex.

1996 ◽  
Vol 199 (12) ◽  
pp. 2745-2755 ◽  
Author(s):  
P Chai ◽  
R Harrykissoon ◽  
R Dudley
Keyword(s):  
Power Output ◽  
Aerodynamic Force ◽  
Force Production ◽  
Power Input ◽  
Flight Mechanics ◽  
Flight Performance ◽  
Metabolic Power ◽  
Significant Extent ◽  
Mechanical Power Output ◽  
Stroke Amplitude

Owing to their small size and hovering locomotion, hummingbirds are the most aerobically active vertebrate endotherms. Can hyperoxia enhance the flight performance of this highly oxygen-dependent group? Hovering performance of ruby-throated hummingbirds (Archilochus colubris) was manipulated non-invasively using hyperoxic but hypodense gas mixtures of sea-level air combined with heliox containing 35% O2. This manipulation sheds light on the interplay among metabolic power input, mechanical power output and aerodynamic force production in limiting flight performance. No significant differences in flight mechanics and oxygen consumption were identified between hyperoxic and normoxic conditions. Thus, at least in the present experimental context, hyperoxia did not change the major metabolic and mechanical parameters; O2 diffusive capacities of the respiratory system were probably not limiting to a significant extent. Compared with hummingbirds in our previous studies, the present experimental birds were heavier, had resultant shorter hover-feeding durations and experienced aerodynamic failure at higher air densities. Because hummingbirds have relatively stable wingbeat frequencies, modulation of power output was attained primarily through variation in stroke amplitude up to near 180 degrees. This result indicates that maximum hovering performance was constrained geometrically and that heavier birds with greater fat loads had less margin for enhancement of power production. Sexual dimorphism in flight adaptation also played a role, with males showing more limited hovering capacities, presumably as a trade-off for increased maneuverability.

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