The Mechanisms and Energetics of Honeybee Swarm Temperature Regulation

1. Free (active) honeybee swarms regulated their core temperature (Tc) generally within 1 °C of 35 °C. They maintained the same temperature around freshly built honeycomb, and in the brood nest of the hive, from ambient temperatures of between at least 1 and 25 °C. Captive (inactive) swarms in the laboratory often allowed Tc to decline below 35 °C. 2. The temperature of the swarm mantle (Tm) varied with the general activity of the swarm as well as with ambient temperature (TA), but in captive swarms (and sometimes at night in free swarms), Tm was generally held above 17 °C, even at TA < 5 °C. 3. Within the swarm, temperatures varied between 36 °C, an upper temperature set-point, and 17 °C, a lower temperature set-point. 4. Before swarm take-off, all temperature gradients in the swarm were abolished and Tm equalled Tc. 5. The regulated Tc and Tm were unrelated to size and passive cooling rates in swarms ranging from 1000 to 30000 bees. 6. The weight-specific metabolic rate of swarms was correlated with TA and Tc, but relatively little affected by swarm size. 7. Bees on the mantle experiencing low temperatures pushed inward, thus contracting the mantle, diminishing the mantle porosity, and filling interior passageways. As a result, their own rate of heat loss, as well as that from the swarm core, decreased. 8. In large tightly clumped swarms, even at TA < 5 °C, the resting metabolic rate of the bees in the swarm core was more than sufficient to maintain Tc at 35 °C or above. The active thermoregulatory metabolism was due to the bees on the swarm mantle. 9. There was little physical exchange of bees between core and mantle at low (< 5 °C) TA. In addition, there was no apparent chemical or acoustic communication between the bees in the swarm mantle that are subjected to the changes of the thermal environments and the bees in the swarm interior that constantly experience 35 °C regardless of TA. 10. The data are summarized in a model of Tc control indicating a primary role of the mantle bees in controlling heat production and heat loss. 11. The possible ecological significance of swarm temperature regulation is discussed.

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Temperature regulation by hypothalamic proportional control with an adjustable set point

Journal of Applied Physiology ◽

10.1152/jappl.1963.18.6.1146 ◽

1963 ◽

Vol 18 (6) ◽

pp. 1146-1154 ◽

Cited By ~ 228

Author(s):

H. T. Hammel ◽

D. C. Jackson ◽

J. A. J. Stolwijk ◽

J. D. Hardy ◽

S. B. Stromme

Keyword(s):

Heat Loss ◽

Core Temperature ◽

Temperature Regulation ◽

Thermal Response ◽

Hypothalamic Temperature ◽

Set Point ◽

Cold Environments ◽

Hot Environment ◽

Skin Temperatures

The role of the hypothalamic and skin temperatures in controlling the thermal response of a resting animal was studied by measurements of 1) hypothalamic, rectal, ear skin, and trunk skin temperatures on the resting dog and rhesus monkey in hot, neutral, and cold environments; and 2) the thermal and metabolic responses of a dog in neutral and cold environments during and immediately after holding the hypothalamus at approximately 39.0 C by means of six thermodes surrounding the hypothalamus and perfused with water. The results indicate that 1) a resting animal shivers in a cold environment with the same or higher hypothalamic temperature as the same animal in a neutral environment; 2) a resting animal pants in a hot environment with the same or lower hypothalamic temperature as the same animal in a neutral environment; 3) the hypothalamus is nonetheless strongly responsive to an increase or decrease of 1 C; 4) the rate of heat loss increases at the onset of sleep while the hypothalamic temperature is falling; 5) the hypothalamic temperature is 1–2 C lower during sleep even though thermoregulatory responses are the same as when awake; 6) the rate of heat loss decreases upon awakening while the hypothalamic temperature is rising. The discussion of these results includes a suggestion that the set point for temperature regulation is 1) decreased by a rising or elevated skin and extrahypothalamic core temperature, 2) increased by a falling or lowered skin and extrahypothalamic core temperature, 3) decreased upon entering and during sleep and is increased upon awakening. hypothalamic temperature; temperature set point; hypothalamic stimulation; dog temperature regulation; monkey temperature regulation Submitted on October 15, 1962

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Temperature regulation in the new-born lamb. IV. The effect of wind and evaporation of water from the coat on metabolic rate and body temperature

Australian Journal of Agricultural Research ◽

10.1071/ar9620082 ◽

1962 ◽

Vol 13 (1) ◽

pp. 82 ◽

Cited By ~ 59

Author(s):

G Alexander

Keyword(s):

Metabolic Rate ◽

Heat Loss ◽

Heat Production ◽

Temperature Regulation ◽

Tap Water ◽

High Heat ◽

Cooling Efficiency ◽

Experimental Conditions ◽

Ambient Temperatures ◽

New Born

The study of temperature regulation in new-born lambs has been extended from dry lambs in "still air" at various ambient temperatures to dry lambs in a wind of 550 cm sec-l, and to lambs whose coats are drying. Exposure to wind resulted in an increased slope of the line relating heat production to ambient temperature, but under the experimental conditions evaporation of water from the coat added approximately the same increment at all ambient temperatures. The effects of wind and evaporation at any one temperature appeared additive. The heat loss from naturally wet new-born lambs less than 1 hr old, in a wind, was greater than in slightly older lambs wetted with tap water. Lambs with hairy coats were able to conserve heat more readily than lambs with fine coats. The cooling efficiency of evaporation from the coat was about 25%. The elevation in temperature of the extremities which follows feeding and persists under conditions of moderate heat loss, appears to be almost abolished under conditions of high heat loss. During the studies on drying lambs, beat loss in many lambs exceeded heat production, and rectal temperature fell, which thus indicated the maximum possible heat production (summit metabolic rate) of which lambs are capable. Lambs from ewes on low or medium levels of feeding during pregnancy cooled more readily than lambs from well-fed ewes.

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Thermoregulation of African and European Honeybees during Foraging, Attack, and Hive Exits and Returns

Journal of Experimental Biology ◽

10.1242/jeb.80.1.217 ◽

1979 ◽

Vol 80 (1) ◽

pp. 217-229 ◽

Cited By ~ 2

Author(s):

HEINRICH BERND

Keyword(s):

Metabolic Rate ◽

Ambient Temperature ◽

Heat Loss ◽

Warm Up ◽

Ambient Temperatures ◽

Thoracic Temperature

1. While foraging, attacking, or leaving or returning to their hives, both the African and European honeybees maintained their thoracic temperature at 30 °C or above, independent of ambient temperature from 7 to 23 °C (in shade). 2. Thoracic temperatures were not significantly different between African and European bees. 3. Thoracic temperatures were significantly different during different activities. Average thoracic temperatures (at ambient temperatures of 8–23 °C) were lowest (30 °C) in bees turning to the hive. They were 31–32 °C during foraging, and 36–38 °C in bees leaving the hive, and in those attacking. The bees thus warm up above their temperature in the hive (32 °C) before leaving the colony. 4. In the laboratory the bees (European) did not maintain the minimum thoracic temperature for continuous flight (27 °C) at 10 °C. When forced to remain in continuous flight for at least 2 min, thoracic temperature averaged 15 °C above ambient temperature from 15 to 25 °C, and was regulated only at high ambient temperatures (30–40 °C). 5. At ambient temperatures > 25 °C, the bees heated up during return to the hive, attack and foraging above the thoracic temperatures they regulated at low ambient temperatures to near the temperatures they regulated during continuous flight. 6. In both African and European bees, attack behaviour and high thoracic temperature are correlated. 7. The data suggest that the bees regulate thoracic temperature by both behavioural and physiological means. It can be inferred that the African bees have a higher metabolic rate than the European, but their smaller size, which facilitates more rapid heat loss, results in similar thoracic temperatures.

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A Twin Study Approach Towards Understanding Genetic Contributions to Body Size and Metabolic Rate

Acta geneticae medicae et gemellologiae twin research ◽

10.1017/s0001566000002567 ◽

1991 ◽

Vol 40 (2) ◽

pp. 133-146 ◽

Cited By ~ 39

Author(s):

J.K. Hewitt ◽

A.J. Stunkard ◽

D. Carroll ◽

J. Sims ◽

J.R. Turner

Keyword(s):

Body Weight ◽

Metabolic Rate ◽

Psychological Stress ◽

Resting Metabolic Rate ◽

Genetic Effect ◽

Set Point ◽

Study Approach ◽

Brief Assessment ◽

High Heritability ◽

Genetic Contributions

AbstractThe genetic and environmental determinants of a brief assessment of metabolic rate at rest and under psychological stress were studied in 40 pairs of monozygotic and 40 pairs of dizygotic young adult male twins. Height, weight and age were employed as covariates. Univariate analyses showed a high heritability for height and weight and moderate heritability for metabolic rate. Classical twin analyses and multivariate genetic modeling indicated that genetic influences on resting metabolic rate were entirely explained by body weight: there was no independent genetic contribution to resting metabolic rate. Metabolic rate under psychological stress, on the other hand, showed a significant genetic effect. The exponent (3/4) in the power function relating body weight to resting metabolic rate was the same as that found in a wide variety of animal species, a value that has been proposed as defining a body weight set point. We speculate that an adult body weight set point is genetically transmitted. Independent genetic effects on resting metabolic rate would be observed only when the normal equilibrium between body weight and metabolic rate is unbalanced during development, aging or disease. The study illustrates the use of multivariate genetic analyses of twin data which may be readily applied to widely used metabolic rate assessments.

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Development of thermoregulation in ducklings

Canadian Journal of Zoology ◽

10.1139/z72-168 ◽

1972 ◽

Vol 50 (10) ◽

pp. 1243-1250 ◽

Cited By ~ 18

Author(s):

G. Untergasser ◽

J. S. Hayward

Keyword(s):

Metabolic Rate ◽

Heat Loss ◽

Cold Resistance ◽

Rapid Development ◽

Metabolic Rates ◽

Ambient Temperatures ◽

Common Eiders

The embryos of mallards and scaups show no evidence of homeothermy before the point of hatching. The ability to thermoregulate develops quickly directly after hatching, so that day-old mallards remain homeothermic for at least 2.5 h at ambient temperatures down to +2 °C. The lowest ambient temperatures at which 1-day-old scaups and common eiders remain homeothermic for at least 2.5 h are −2 °C and −7 °C respectively. This rapid development of cold resistance is related to increases in peak metabolic rates and insulative capacities. In embryos of pipped eggs, metabolic rates do not exceed 1.1 ml O2/g h for mallards and 1.6 ml/g h for scaups, while the peak metabolic rates of the day-old young are 6.1 and 7.0 ml/g h respectively. One-day-old common eiders have a peak metabolic rate of about 5 ml/g h. After an age of 3 days, cold resistance increases with age while peak metabolic rates decrease, indicating that reduced heat loss contributes to increased cold resistance. At an age of 7 days, mallards can maintain homeothermy for at least 2.5 h at −4 °C, scaups at −14 °C, and common eiders at −16 °C. Insulation indices of eider ducklings are significantly higher than those of young mallards and scaups.

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Role of insulin in thermogenic responses to refeeding in 3-day-fasted rats

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1983.245.2.e160 ◽

1983 ◽

Vol 245 (2) ◽

pp. E160-E165 ◽

Cited By ~ 1

Author(s):

N. J. Rothwell ◽

M. E. Saville ◽

M. J. Stock

Keyword(s):

Metabolic Rate ◽

Resting Metabolic Rate ◽

Insulin Injection ◽

Zucker Rats ◽

Corn Flour ◽

Plasma Insulin Levels ◽

Obese Zucker Rats ◽

Fasted Rats ◽

Thermogenic Response

Refeeding 3-day-fasted rats with 40 kJ carbohydrate (CHO; corn flour) or protein (gelatin) caused a rise in plasma insulin levels 3 h later, but refeeding fat or injection of norepinephrine (400 micrograms/kg) had no effect. Injection of insulin (0.25 U) caused a 15% rise in metabolic rate 24 h later in fasted rats that could be inhibited by treatment with propranolol. Refeeding rats with a single CHO meal produced an increase in oxygen consumption (15%) 24 h later that was inhibited by injection of diazoxide or 2-deoxy-D-glucose given at the time of the meal. The thermogenic response to insulin injection was unaffected by treatment with diazoxide or 2-deoxy-D-glucose. Genetically obese Zucker rats failed to increase metabolic rate after insulin or CHO. In normally fed lean rats, maintained on a stock diet or a palatable cafeteria diet, insulin (4 U) enhanced the thermogenic response to norepinephrine and stimulated resting metabolic rate (16%) in the cafeteria-fed rats. These data suggest that insulin is involved in the thermogenic responses to food and catecholamines.

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THE INFLUENCE OF CLIMATE ON METABOLIC AND THERMAL RESPONSES OF INFANT CARIBOU

Canadian Journal of Zoology ◽

10.1139/z61-079 ◽

1961 ◽

Vol 39 (6) ◽

pp. 845-856 ◽

Cited By ~ 22

Author(s):

J. S. Hart ◽

O. Heroux ◽

W. H. Cottle ◽

C. A. Mills

Keyword(s):

Metabolic Rate ◽

Heat Loss ◽

Temperature Regulation ◽

Weather Conditions ◽

Wind Chill ◽

Prediction Of Mortality ◽

Cold Wind

Metabolic and thermal responses of infant caribou to climate were measured during the June calving period on the barrens in the area of Mosquito Lake and Beverly Lake, N.W.T. It was found that temperature regulation was well established at birth and that the calves were very sensitive metabolically to cold, wind, and precipitation. The metabolic rate was doubled by a lowering of temperature to about 0 °C, but cold combined with wind and precipitation elevated the metabolic rate to over five times the resting value. Calves which were exposed without protection to such conditions eventually became hypothermic and died. Weather conditions during storms on the barrens are sufficiently severe to produce some mortality in animals exposed without protection. The possibilities for prediction of mortality from wind chill values and estimated fur heat loss are discussed.

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Effect of age on cold acclimation in rats: metabolic and behavioral responses

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1991.260.2.r284 ◽

1991 ◽

Vol 260 (2) ◽

pp. R284-R289 ◽

Cited By ~ 3

Author(s):

T. L. Owen ◽

R. L. Spencer ◽

S. P. Duckles

Keyword(s):

Body Temperature ◽

Metabolic Rate ◽

Cold Acclimation ◽

Cold Exposure ◽

Resting Metabolic Rate ◽

Age Groups ◽

Behavioral Responses ◽

Mortality And Morbidity ◽

Ambient Temperatures ◽

Reduced Body

To determine whether senescence affects the metabolic and behavioral responses of rats to chronic cold exposure, 8- and 22-mo-old male Fischer 344 rats were studied before and after 6 wk of cold (6-10 degrees C) exposure. Measurements of body weight, food consumption, oxygen consumption, body temperature, and ambient temperature selection in a thermocline (7-37 degrees C linear gradient) were made at regular intervals throughout the acclimation period. Before acclimation, age groups differed significantly only by weight. During acclimation, older rats had increased mortality and morbidity below 10 degrees C. After acclimation at 10 degrees C, younger and older rats both selected cooler ambient temperatures (7 and 5 degrees C cooler than preacclimation, respectively), and older rats had a significantly greater decrease in body temperature in the thermocline. Both age groups increased resting metabolic rate at 25 degrees C with cold acclimation (16.5 and 10% increase for younger and older rats, respectively). This study indicates distinct differences in metabolic and behavioral responses of younger and older rats to cold acclimation. Chronic cold exposure is detrimental to thermoregulatory function in older rats, since it is not as effective in stimulating sustained increases in metabolic rate in older rats as in young adults and it leads to a preference for cooler ambient temperatures, resulting in increased heat loss and reduced body temperature.

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